Project import
diff --git a/libpng/ANNOUNCE b/libpng/ANNOUNCE
new file mode 100644
index 0000000..4dae783
--- /dev/null
+++ b/libpng/ANNOUNCE
@@ -0,0 +1,52 @@
+Libpng 1.6.20 - December 3, 2015
+
+This is a public release of libpng, intended for use in production codes.
+
+Files available for download:
+
+Source files with LF line endings (for Unix/Linux) and with a
+"configure" script
+
+ libpng-1.6.20.tar.xz (LZMA-compressed, recommended)
+ libpng-1.6.20.tar.gz
+
+Source files with CRLF line endings (for Windows), without the
+"configure" script
+
+ /scratch/glennrp/Libpng16/lpng1620.7z (LZMA-compressed, recommended)
+ /scratch/glennrp/Libpng16/lpng1620.zip
+
+Other information:
+
+ libpng-1.6.20-README.txt
+ libpng-1.6.20-LICENSE.txt
+ libpng-1.6.20-*.asc (armored detached GPG signatures)
+
+Changes since the last public release (1.6.19):
+ Avoid potential pointer overflow/underflow in png_handle_sPLT() and
+ png_handle_pCAL() (Bug report by John Regehr).
+ Fixed incorrect implementation of png_set_PLTE() that uses png_ptr
+ not info_ptr, that left png_set_PLTE() open to the CVE-2015-8126
+ vulnerability.
+ Backported tests from libpng-1.7.0beta69.
+ Fixed an error in handling of bad zlib CMINFO field in pngfix, found by
+ American Fuzzy Lop, reported by Brian Carpenter. inflate() doesn't
+ immediately fault a bad CMINFO field; instead a 'too far back' error
+ happens later (at least some times). pngfix failed to limit CMINFO to
+ the allowed values but then assumed that window_bits was in range,
+ triggering an assert. The bug is mostly harmless; the PNG file cannot
+ be fixed.
+ In libpng 1.6 zlib initialization was changed to use the window size
+ in the zlib stream, not a fixed value. This causes some invalid images,
+ where CINFO is too large, to display 'correctly' if the rest of the
+ data is valid. This provides a workaround for zlib versions where the
+ error arises (ones that support the API change to use the window size
+ in the stream).
+
+Send comments/corrections/commendations to png-mng-implement at lists.sf.net
+(subscription required; visit
+https://lists.sourceforge.net/lists/listinfo/png-mng-implement
+to subscribe)
+or to glennrp at users.sourceforge.net
+
+Glenn R-P
diff --git a/libpng/Android.mk b/libpng/Android.mk
new file mode 100644
index 0000000..959b73c
--- /dev/null
+++ b/libpng/Android.mk
@@ -0,0 +1,98 @@
+LOCAL_PATH:= $(call my-dir)
+
+# We need to build this for both the device (as a shared library)
+# and the host (as a static library for tools to use).
+
+common_SRC_FILES := \
+ png.c \
+ pngerror.c \
+ pngget.c \
+ pngmem.c \
+ pngpread.c \
+ pngread.c \
+ pngrio.c \
+ pngrtran.c \
+ pngrutil.c \
+ pngset.c \
+ pngtrans.c \
+ pngwio.c \
+ pngwrite.c \
+ pngwtran.c \
+ pngwutil.c \
+
+ifeq ($(ARCH_ARM_HAVE_NEON),true)
+my_cflags_arm := -DPNG_ARM_NEON_OPT=2
+endif
+
+my_cflags_arm64 := -DPNG_ARM_NEON_OPT=2
+
+# BUG: http://llvm.org/PR19472 - SLP vectorization (on ARM at least) crashes
+# when we can't lower a vectorized bswap.
+my_cflags_arm += -fno-slp-vectorize
+
+my_src_files_arm := \
+ arm/arm_init.c \
+ arm/filter_neon.S \
+ arm/filter_neon_intrinsics.c
+
+
+common_CFLAGS := -std=gnu89 #-fvisibility=hidden ## -fomit-frame-pointer
+
+# For the host
+# =====================================================
+
+include $(CLEAR_VARS)
+LOCAL_SRC_FILES := $(common_SRC_FILES)
+LOCAL_CFLAGS += $(common_CFLAGS)
+LOCAL_ASFLAGS += $(common_ASFLAGS)
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)
+LOCAL_STATIC_LIBRARIES := libz
+LOCAL_MODULE:= libpng
+include $(BUILD_HOST_STATIC_LIBRARY)
+
+
+# For the device (static)
+# =====================================================
+
+include $(CLEAR_VARS)
+LOCAL_CLANG := true
+LOCAL_SRC_FILES := $(common_SRC_FILES)
+LOCAL_CFLAGS += $(common_CFLAGS) -ftrapv
+LOCAL_CFLAGS_arm := $(my_cflags_arm)
+LOCAL_ASFLAGS += $(common_ASFLAGS)
+LOCAL_SRC_FILES_arm := $(my_src_files_arm)
+LOCAL_CFLAGS_arm64 := $(my_cflags_arm64)
+LOCAL_SRC_FILES_arm64 := $(my_src_files_arm)
+LOCAL_ADDRESS_SANITIZER := false
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)
+LOCAL_SHARED_LIBRARIES := libz
+LOCAL_MODULE:= libpng
+include $(BUILD_STATIC_LIBRARY)
+
+# For the device (shared)
+# =====================================================
+
+include $(CLEAR_VARS)
+LOCAL_CLANG := true
+LOCAL_SRC_FILES := $(common_SRC_FILES)
+LOCAL_CFLAGS += $(common_CFLAGS) -ftrapv
+LOCAL_CFLAGS_arm := $(my_cflags_arm)
+LOCAL_ASFLAGS += $(common_ASFLAGS)
+LOCAL_SRC_FILES_arm := $(my_src_files_arm)
+LOCAL_CFLAGS_arm64 := $(my_cflags_arm64)
+LOCAL_SRC_FILES_arm64 := $(my_src_files_arm)
+LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)
+LOCAL_SHARED_LIBRARIES := libz
+LOCAL_MODULE:= libpng
+include $(BUILD_SHARED_LIBRARY)
+
+# For testing
+# =====================================================
+
+include $(CLEAR_VARS)
+LOCAL_CLANG := true
+LOCAL_SRC_FILES:= pngtest.c
+LOCAL_MODULE := pngtest
+LOCAL_SHARED_LIBRARIES:= libpng libz
+LOCAL_MODULE_TAGS := debug
+include $(BUILD_EXECUTABLE)
diff --git a/libpng/CHANGES b/libpng/CHANGES
new file mode 100644
index 0000000..28094fd
--- /dev/null
+++ b/libpng/CHANGES
@@ -0,0 +1,5456 @@
+#if 0
+CHANGES - changes for libpng
+
+version 0.1 [March 29, 1995]
+ initial work-in-progress release
+
+version 0.2 [April 1, 1995]
+ added reader into png.h
+ fixed small problems in stub file
+
+version 0.3 [April 8, 1995]
+ added pull reader
+ split up pngwrite.c to several files
+ added pnglib.txt
+ added example.c
+ cleaned up writer, adding a few new transformations
+ fixed some bugs in writer
+ interfaced with zlib 0.5
+ added K&R support
+ added check for 64 KB blocks for 16 bit machines
+
+version 0.4 [April 26, 1995]
+ cleaned up code and commented code
+ simplified time handling into png_time
+ created png_color_16 and png_color_8 to handle color needs
+ cleaned up color type defines
+ fixed various bugs
+ made various names more consistent
+ interfaced with zlib 0.71
+ cleaned up zTXt reader and writer (using zlib's Reset functions)
+ split transformations into pngrtran.c and pngwtran.c
+
+version 0.5 [April 30, 1995]
+ interfaced with zlib 0.8
+ fixed many reading and writing bugs
+ saved using 3 spaces instead of tabs
+
+version 0.6 [May 1, 1995]
+ first beta release
+ added png_large_malloc() and png_large_free()
+ added png_size_t
+ cleaned up some compiler warnings
+ added png_start_read_image()
+
+version 0.7 [June 24, 1995]
+ cleaned up lots of bugs
+ finished dithering and other stuff
+ added test program
+ changed name from pnglib to libpng
+
+version 0.71 [June 26, 1995]
+ changed pngtest.png for zlib 0.93
+ fixed error in libpng.txt and example.c
+
+version 0.8 [August 20, 1995]
+ cleaned up some bugs
+ added png_set_filler()
+ split up pngstub.c into pngmem.c, pngio.c, and pngerror.c
+ added #define's to remove unwanted code
+ moved png_info_init() to png.c
+ added old_size into png_realloc()
+ added functions to manually set filtering and compression info
+ changed compression parameters based on image type
+ optimized filter selection code
+ added version info
+ changed external functions passing floats to doubles (k&r problems?)
+ put all the configurable stuff in pngconf.h
+ enabled png_set_shift to work with paletted images on read
+ added png_read_update_info() - updates info structure with transformations
+
+Version 0.81 [August, 1995]
+ incorporated Tim Wegner's medium model code (thanks, Tim)
+
+Version 0.82 [September, 1995]
+ [unspecified changes]
+
+Version 0.85 [December, 1995]
+ added more medium model code (almost everything's a far)
+ added i/o, error, and memory callback functions
+ fixed some bugs (16-bit, 4-bit interlaced, etc.)
+ added first run progressive reader (barely tested)
+
+Version 0.86 [January, 1996]
+ fixed bugs
+ improved documentation
+
+Version 0.87 [January, 1996]
+ fixed medium model bugs
+ fixed other bugs introduced in 0.85 and 0.86
+ added some minor documentation
+
+Version 0.88 [January, 1996]
+ fixed progressive bugs
+ replaced tabs with spaces
+ cleaned up documentation
+ added callbacks for read/write and warning/error functions
+
+Version 0.89 [June 5, 1996]
+ Added new initialization API to make libpng work better with shared libs
+ we now have png_create_read_struct(), png_create_write_struct(),
+ png_create_info_struct(), png_destroy_read_struct(), and
+ png_destroy_write_struct() instead of the separate calls to
+ malloc and png_read_init(), png_info_init(), and png_write_init()
+ Changed warning/error callback functions to fix bug - this means you
+ should use the new initialization API if you were using the old
+ png_set_message_fn() calls, and that the old API no longer exists
+ so that people are aware that they need to change their code
+ Changed filter selection API to allow selection of multiple filters
+ since it didn't work in previous versions of libpng anyways
+ Optimized filter selection code
+ Fixed png_set_background() to allow using an arbitrary RGB color for
+ paletted images
+ Fixed gamma and background correction for paletted images, so
+ png_correct_palette is not needed unless you are correcting an
+ external palette (you will need to #define PNG_CORRECT_PALETTE_SUPPORTED
+ in pngconf.h) - if nobody uses this, it may disappear in the future.
+ Fixed bug with Borland 64K memory allocation (Alexander Lehmann)
+ Fixed bug in interlace handling (Smarasderagd, I think)
+ Added more error checking for writing and image to reduce invalid files
+ Separated read and write functions so that they won't both be linked
+ into a binary when only reading or writing functionality is used
+ New pngtest image also has interlacing and zTXt
+ Updated documentation to reflect new API
+
+Version 0.89c [June 17, 1996]
+ Bug fixes.
+
+Version 0.90 [January, 1997]
+ Made CRC errors/warnings on critical and ancillary chunks configurable
+ libpng will use the zlib CRC routines by (compile-time) default
+ Changed DOS small/medium model memory support - needs zlib 1.04 (Tim Wegner)
+ Added external C++ wrapper statements to png.h (Gilles Dauphin)
+ Allow PNG file to be read when some or all of file signature has already
+ been read from the beginning of the stream. ****This affects the size
+ of info_struct and invalidates all programs that use a shared libpng****
+ Fixed png_filler() declarations
+ Fixed? background color conversions
+ Fixed order of error function pointers to match documentation
+ Current chunk name is now available in png_struct to reduce the number
+ of nearly identical error messages (will simplify multi-lingual
+ support when available)
+ Try to get ready for unknown-chunk callback functions:
+ - previously read critical chunks are flagged, so the chunk handling
+ routines can determine if the chunk is in the right place
+ - all chunk handling routines have the same prototypes, so we will
+ be able to handle all chunks via a callback mechanism
+ Try to fix Linux "setjmp" buffer size problems
+ Removed png_large_malloc, png_large_free, and png_realloc functions.
+
+Version 0.95 [March, 1997]
+ Fixed bug in pngwutil.c allocating "up_row" twice and "avg_row" never
+ Fixed bug in PNG file signature compares when start != 0
+ Changed parameter type of png_set_filler(...filler...) from png_byte
+ to png_uint_32
+ Added test for MACOS to ensure that both math.h and fp.h are not #included
+ Added macros for libpng to be compiled as a Windows DLL (Andreas Kupries)
+ Added "packswap" transformation, which changes the endianness of
+ packed-pixel bytes (Kevin Bracey)
+ Added "strip_alpha" transformation, which removes the alpha channel of
+ input images without using it (not necessarily a good idea)
+ Added "swap_alpha" transformation, which puts the alpha channel in front
+ of the color bytes instead of after
+ Removed all implicit variable tests which assume NULL == 0 (I think)
+ Changed several variables to "png_size_t" to show 16/32-bit limitations
+ Added new pCAL chunk read/write support
+ Added experimental filter selection weighting (Greg Roelofs)
+ Removed old png_set_rgbx() and png_set_xrgb() functions that have been
+ obsolete for about 2 years now (use png_set_filler() instead)
+ Added macros to read 16- and 32-bit ints directly from buffer, to be
+ used only on those systems that support it (namely PowerPC and 680x0)
+ With some testing, this may become the default for MACOS/PPC systems.
+ Only calculate CRC on data if we are going to use it
+ Added macros for zTXt compression type PNG_zTXt_COMPRESSION_???
+ Added macros for simple libpng debugging output selectable at compile time
+ Removed PNG_READ_END_MODE in progressive reader (Smarasderagd)
+ More description of info_struct in libpng.txt and png.h
+ More instructions in example.c
+ More chunk types tested in pngtest.c
+ Renamed pngrcb.c to pngset.c, and all png_read_<chunk> functions to be
+ png_set_<chunk>. We now have corresponding png_get_<chunk>
+ functions in pngget.c to get information in info_ptr. This isolates
+ the application from the internal organization of png_info_struct
+ (good for shared library implementations).
+
+Version 0.96 [May, 1997]
+ Fixed serious bug with < 8bpp images introduced in 0.95
+ Fixed 256-color transparency bug (Greg Roelofs)
+ Fixed up documentation (Greg Roelofs, Laszlo Nyul)
+ Fixed "error" in pngconf.h for Linux setjmp() behavior
+ Fixed DOS medium model support (Tim Wegner)
+ Fixed png_check_keyword() for case with error in static string text
+ Added read of CRC after IEND chunk for embedded PNGs (Laszlo Nyul)
+ Added typecasts to quiet compiler errors
+ Added more debugging info
+
+Version 0.97 [January, 1998]
+ Removed PNG_USE_OWN_CRC capability
+ Relocated png_set_crc_action from pngrutil.c to pngrtran.c
+ Fixed typecasts of "new_key", etc. (Andreas Dilger)
+ Added RFC 1152 [sic] date support
+ Fixed bug in gamma handling of 4-bit grayscale
+ Added 2-bit grayscale gamma handling (Glenn R-P)
+ Added more typecasts. 65536L becomes (png_uint_32)65536L, etc. (Glenn R-P)
+ Minor corrections in libpng.txt
+ Added simple sRGB support (Glenn R-P)
+ Easier conditional compiling, e.g.,
+ define PNG_READ/WRITE_NOT_FULLY_SUPPORTED;
+ all configurable options can be selected from command-line instead
+ of having to edit pngconf.h (Glenn R-P)
+ Fixed memory leak in pngwrite.c (free info_ptr->text) (Glenn R-P)
+ Added more conditions for png_do_background, to avoid changing
+ black pixels to background when a background is supplied and
+ no pixels are transparent
+ Repaired PNG_NO_STDIO behavior
+ Tested NODIV support and made it default behavior (Greg Roelofs)
+ Added "-m" option and PNGTEST_DEBUG_MEMORY to pngtest (John Bowler)
+ Regularized version numbering scheme and bumped shared-library major
+ version number to 2 to avoid problems with libpng 0.89 apps
+ (Greg Roelofs)
+
+Version 0.98 [January, 1998]
+ Cleaned up some typos in libpng.txt and in code documentation
+ Fixed memory leaks in pCAL chunk processing (Glenn R-P and John Bowler)
+ Cosmetic change "display_gamma" to "screen_gamma" in pngrtran.c
+ Changed recommendation about file_gamma for PC images to .51 from .45,
+ in example.c and libpng.txt, added comments to distinguish between
+ screen_gamma, viewing_gamma, and display_gamma.
+ Changed all references to RFC1152 to read RFC1123 and changed the
+ PNG_TIME_RFC1152_SUPPORTED macro to PNG_TIME_RFC1123_SUPPORTED
+ Added png_invert_alpha capability (Glenn R-P -- suggestion by Jon Vincent)
+ Changed srgb_intent from png_byte to int to avoid compiler bugs
+
+Version 0.99 [January 30, 1998]
+ Free info_ptr->text instead of end_info_ptr->text in pngread.c (John Bowler)
+ Fixed a longstanding "packswap" bug in pngtrans.c
+ Fixed some inconsistencies in pngconf.h that prevented compiling with
+ PNG_READ_GAMMA_SUPPORTED and PNG_READ_hIST_SUPPORTED undefined
+ Fixed some typos and made other minor rearrangement of libpng.txt (Andreas)
+ Changed recommendation about file_gamma for PC images to .50 from .51 in
+ example.c and libpng.txt, and changed file_gamma for sRGB images to .45
+ Added a number of functions to access information from the png structure
+ png_get_image_height(), etc. (Glenn R-P, suggestion by Brad Pettit)
+ Added TARGET_MACOS similar to zlib-1.0.8
+ Define PNG_ALWAYS_EXTERN when __MWERKS__ && WIN32 are defined
+ Added type casting to all png_malloc() function calls
+
+Version 0.99a [January 31, 1998]
+ Added type casts and parentheses to all returns that return a value.(Tim W.)
+
+Version 0.99b [February 4, 1998]
+ Added type cast png_uint_32 on malloc function calls where needed.
+ Changed type of num_hist from png_uint_32 to int (same as num_palette).
+ Added checks for rowbytes overflow, in case png_size_t is less than 32 bits.
+ Renamed makefile.elf to makefile.lnx.
+
+Version 0.99c [February 7, 1998]
+ More type casting. Removed erroneous overflow test in pngmem.c.
+ Added png_buffered_memcpy() and png_buffered_memset(), apply them to rowbytes.
+ Added UNIX manual pages libpng.3 (incorporating libpng.txt) and png.5.
+
+Version 0.99d [February 11, 1998]
+ Renamed "far_to_near()" "png_far_to_near()"
+ Revised libpng.3
+ Version 99c "buffered" operations didn't work as intended. Replaced them
+ with png_memcpy_check() and png_memset_check().
+ Added many "if (png_ptr == NULL) return" to quell compiler warnings about
+ unused png_ptr, mostly in pngget.c and pngset.c.
+ Check for overlength tRNS chunk present when indexed-color PLTE is read.
+ Cleaned up spelling errors in libpng.3/libpng.txt
+ Corrected a problem with png_get_tRNS() which returned undefined trans array
+
+Version 0.99e [February 28, 1998]
+ Corrected png_get_tRNS() again.
+ Add parentheses for easier reading of pngget.c, fixed "||" should be "&&".
+ Touched up example.c to make more of it compileable, although the entire
+ file still can't be compiled (Willem van Schaik)
+ Fixed a bug in png_do_shift() (Bryan Tsai)
+ Added a space in png.h prototype for png_write_chunk_start()
+ Replaced pngtest.png with one created with zlib 1.1.1
+ Changed pngtest to report PASS even when file size is different (Jean-loup G.)
+ Corrected some logic errors in png_do_invert_alpha() (Chris Patterson)
+
+Version 0.99f [March 5, 1998]
+ Corrected a bug in pngpread() introduced in version 99c (Kevin Bracey)
+ Moved makefiles into a "scripts" directory, and added INSTALL instruction file
+ Added makefile.os2 and pngos2.def (A. Zabolotny) and makefile.s2x (W. Sebok)
+ Added pointers to "note on libpng versions" in makefile.lnx and README
+ Added row callback feature when reading and writing nonprogressive rows
+ and added a test of this feature in pngtest.c
+ Added user transform callbacks, with test of the feature in pngtest.c
+
+Version 0.99g [March 6, 1998, morning]
+ Minor changes to pngtest.c to suppress compiler warnings.
+ Removed "beta" language from documentation.
+
+Version 0.99h [March 6, 1998, evening]
+ Minor changes to previous minor changes to pngtest.c
+ Changed PNG_READ_NOT_FULLY_SUPPORTED to PNG_READ_TRANSFORMS_NOT_SUPPORTED
+ and added PNG_PROGRESSIVE_READ_NOT_SUPPORTED macro
+ Added user transform capability
+
+Version 1.00 [March 7, 1998]
+ Changed several typedefs in pngrutil.c
+ Added makefile.wat (Pawel Mrochen), updated makefile.tc3 (Willem van Schaik)
+ Replaced "while(1)" with "for(;;)"
+ Added PNGARG() to prototypes in pngtest.c and removed some prototypes
+ Updated some of the makefiles (Tom Lane)
+ Changed some typedefs (s_start, etc.) in pngrutil.c
+ Fixed dimensions of "short_months" array in pngwrite.c
+ Replaced ansi2knr.c with the one from jpeg-v6
+
+Version 1.0.0 [March 8, 1998]
+ Changed name from 1.00 to 1.0.0 (Adam Costello)
+ Added smakefile.ppc (with SCOPTIONS.ppc) for Amiga PPC (Andreas Kleinert)
+
+Version 1.0.0a [March 9, 1998]
+ Fixed three bugs in pngrtran.c to make gamma+background handling consistent
+ (Greg Roelofs)
+ Changed format of the PNG_LIBPNG_VER integer to xyyzz instead of xyz
+ for major, minor, and bugfix releases. This is 10001. (Adam Costello,
+ Tom Lane)
+ Make months range from 1-12 in png_convert_to_rfc1123
+
+Version 1.0.0b [March 13, 1998]
+ Quieted compiler complaints about two empty "for" loops in pngrutil.c
+ Minor changes to makefile.s2x
+ Removed #ifdef/#endif around a png_free() in pngread.c
+
+Version 1.0.1 [March 14, 1998]
+ Changed makefile.s2x to reduce security risk of using a relative pathname
+ Fixed some typos in the documentation (Greg).
+ Fixed a problem with value of "channels" returned by png_read_update_info()
+
+Version 1.0.1a [April 21, 1998]
+ Optimized Paeth calculations by replacing abs() function calls with intrinsics
+ plus other loop optimizations. Improves avg decoding speed by about 20%.
+ Commented out i386istic "align" compiler flags in makefile.lnx.
+ Reduced the default warning level in some makefiles, to make them consistent.
+ Removed references to IJG and JPEG in the ansi2knr.c copyright statement.
+ Fixed a bug in png_do_strip_filler with XXRRGGBB => RRGGBB transformation.
+ Added grayscale and 16-bit capability to png_do_read_filler().
+ Fixed a bug in pngset.c, introduced in version 0.99c, that sets rowbytes
+ too large when writing an image with bit_depth < 8 (Bob Dellaca).
+ Corrected some bugs in the experimental weighted filtering heuristics.
+ Moved a misplaced pngrutil code block that truncates tRNS if it has more
+ than num_palette entries -- test was done before num_palette was defined.
+ Fixed a png_convert_to_rfc1123() bug that converts day 31 to 0 (Steve Eddins).
+ Changed compiler flags in makefile.wat for better optimization
+ (Pawel Mrochen).
+
+Version 1.0.1b [May 2, 1998]
+ Relocated png_do_gray_to_rgb() within png_do_read_transformations() (Greg).
+ Relocated the png_composite macros from pngrtran.c to png.h (Greg).
+ Added makefile.sco (contributed by Mike Hopkirk).
+ Fixed two bugs (missing definitions of "istop") introduced in libpng-1.0.1a.
+ Fixed a bug in pngrtran.c that would set channels=5 under some circumstances.
+ More work on the Paeth-filtering, achieving imperceptible speedup
+ (A Kleinert).
+ More work on loop optimization which may help when compiled with C++
+ compilers.
+ Added warnings when people try to use transforms they've defined out.
+ Collapsed 4 "i" and "c" loops into single "i" loops in pngrtran and pngwtran.
+ Revised paragraph about png_set_expand() in libpng.txt and libpng.3 (Greg)
+
+Version 1.0.1c [May 11, 1998]
+ Fixed a bug in pngrtran.c (introduced in libpng-1.0.1a) where the masks for
+ filler bytes should have been 0xff instead of 0xf.
+ Added max_pixel_depth=32 in pngrutil.c when using FILLER with palette images.
+ Moved PNG_WRITE_WEIGHTED_FILTER_SUPPORTED and PNG_WRITE_FLUSH_SUPPORTED
+ out of the PNG_WRITE_TRANSFORMS_NOT_SUPPORTED block of pngconf.h
+ Added "PNG_NO_WRITE_TRANSFORMS" etc., as alternatives for *_NOT_SUPPORTED,
+ for consistency, in pngconf.h
+ Added individual "ifndef PNG_NO_[CAPABILITY]" in pngconf.h to make it easier
+ to remove unwanted capabilities via the compile line
+ Made some corrections to grammar (which, it's) in documentation (Greg).
+ Corrected example.c, use of row_pointers in png_write_image().
+
+Version 1.0.1d [May 24, 1998]
+ Corrected several statements that used side effects illegally in pngrutil.c
+ and pngtrans.c, that were introduced in version 1.0.1b
+ Revised png_read_rows() to avoid repeated if-testing for NULL (A Kleinert)
+ More corrections to example.c, use of row_pointers in png_write_image()
+ and png_read_rows().
+ Added pngdll.mak and pngdef.pas to scripts directory, contributed by
+ Bob Dellaca, to make a png32bd.dll with Borland C++ 4.5
+ Fixed error in example.c with png_set_text: num_text is 3, not 2 (Guido V.)
+ Changed several loops from count-down to count-up, for consistency.
+
+Version 1.0.1e [June 6, 1998]
+ Revised libpng.txt and libpng.3 description of png_set_read|write_fn(), and
+ added warnings when people try to set png_read_fn and png_write_fn in
+ the same structure.
+ Added a test such that png_do_gamma will be done when num_trans==0
+ for truecolor images that have defined a background. This corrects an
+ error that was introduced in libpng-0.90 that can cause gamma processing
+ to be skipped.
+ Added tests in png.h to include "trans" and "trans_values" in structures
+ when PNG_READ_BACKGROUND_SUPPORTED or PNG_READ_EXPAND_SUPPORTED is defined.
+ Add png_free(png_ptr->time_buffer) in png_destroy_read_struct()
+ Moved png_convert_to_rfc_1123() from pngwrite.c to png.c
+ Added capability for user-provided malloc_fn() and free_fn() functions,
+ and revised pngtest.c to demonstrate their use, replacing the
+ PNGTEST_DEBUG_MEM feature.
+ Added makefile.w32, for Microsoft C++ 4.0 and later (Tim Wegner).
+
+Version 1.0.2 [June 14, 1998]
+ Fixed two bugs in makefile.bor .
+
+Version 1.0.2a [December 30, 1998]
+ Replaced and extended code that was removed from png_set_filler() in 1.0.1a.
+ Fixed a bug in png_do_filler() that made it fail to write filler bytes in
+ the left-most pixel of each row (Kevin Bracey).
+ Changed "static pngcharp tIME_string" to "static char tIME_string[30]"
+ in pngtest.c (Duncan Simpson).
+ Fixed a bug in pngtest.c that caused pngtest to try to write a tIME chunk
+ even when no tIME chunk was present in the source file.
+ Fixed a problem in pngrutil.c: gray_to_rgb didn't always work with 16-bit.
+ Fixed a problem in png_read_push_finish_row(), which would not skip some
+ passes that it should skip, for images that are less than 3 pixels high.
+ Interchanged the order of calls to png_do_swap() and png_do_shift()
+ in pngwtran.c (John Cromer).
+ Added #ifdef PNG_DEBUG/#endif surrounding use of PNG_DEBUG in png.h .
+ Changed "bad adaptive filter type" from error to warning in pngrutil.c .
+ Fixed a documentation error about default filtering with 8-bit indexed-color.
+ Separated the PNG_NO_STDIO macro into PNG_NO_STDIO and PNG_NO_CONSOLE_IO
+ (L. Peter Deutsch).
+ Added png_set_rgb_to_gray() and png_get_rgb_to_gray_status() functions.
+ Added png_get_copyright() and png_get_header_version() functions.
+ Revised comments on png_set_progressive_read_fn() in libpng.txt and example.c
+ Added information about debugging in libpng.txt and libpng.3 .
+ Changed "ln -sf" to "ln -s -f" in makefile.s2x, makefile.lnx, and
+ makefile.sco.
+ Removed lines after Dynamic Dependencies" in makefile.aco .
+ Revised makefile.dec to make a shared library (Jeremie Petit).
+ Removed trailing blanks from all files.
+
+Version 1.0.2a [January 6, 1999]
+ Removed misplaced #endif and #ifdef PNG_NO_EXTERN near the end of png.h
+ Added "if" tests to silence complaints about unused png_ptr in png.h and png.c
+ Changed "check_if_png" function in example.c to return true (nonzero) if PNG.
+ Changed libpng.txt to demonstrate png_sig_cmp() instead of png_check_sig()
+ which is obsolete.
+
+Version 1.0.3 [January 14, 1999]
+ Added makefile.hux, for Hewlett Packard HPUX 10.20 and 11.00 (Jim Rice)
+ Added a statement of Y2K compliance in png.h, libpng.3, and Y2KINFO.
+
+Version 1.0.3a [August 12, 1999]
+ Added check for PNG_READ_INTERLACE_SUPPORTED in pngread.c; issue a warning
+ if an attempt is made to read an interlaced image when it's not supported.
+ Added check if png_ptr->trans is defined before freeing it in pngread.c
+ Modified the Y2K statement to include versions back to version 0.71
+ Fixed a bug in the check for valid IHDR bit_depth/color_types in pngrutil.c
+ Modified makefile.wat (added -zp8 flag, ".symbolic", changed some comments)
+ Replaced leading blanks with tab characters in makefile.hux
+ Changed "dworkin.wustl.edu" to "ccrc.wustl.edu" in various documents.
+ Changed (float)red and (float)green to (double)red, (double)green
+ in png_set_rgb_to_gray() to avoid "promotion" problems in AIX.
+ Fixed a bug in pngconf.h that omitted <stdio.h> when PNG_DEBUG==0 (K Bracey).
+ Reformatted libpng.3 and libpngpf.3 with proper fonts (script by J. vanZandt).
+ Updated documentation to refer to the PNG-1.2 specification.
+ Removed ansi2knr.c and left pointers to the latest source for ansi2knr.c
+ in makefile.knr, INSTALL, and README (L. Peter Deutsch)
+ Fixed bugs in calculation of the length of rowbytes when adding alpha
+ channels to 16-bit images, in pngrtran.c (Chris Nokleberg)
+ Added function png_set_user_transform_info() to store user_transform_ptr,
+ user_depth, and user_channels into the png_struct, and a function
+ png_get_user_transform_ptr() to retrieve the pointer (Chris Nokleberg)
+ Added function png_set_empty_plte_permitted() to make libpng useable
+ in MNG applications.
+ Corrected the typedef for png_free_ptr in png.h (Jesse Jones).
+ Correct gamma with srgb is 45455 instead of 45000 in pngrutil.c, to be
+ consistent with PNG-1.2, and allow variance of 500 before complaining.
+ Added assembler code contributed by Intel in file pngvcrd.c and modified
+ makefile.w32 to use it (Nirav Chhatrapati, INTEL Corporation,
+ Gilles Vollant)
+ Changed "ln -s -f" to "ln -f -s" in the makefiles to make Solaris happy.
+ Added some aliases for png_set_expand() in pngrtran.c, namely
+ png_set_expand_PLTE(), png_set_expand_depth(), and png_set_expand_tRNS()
+ (Greg Roelofs, in "PNG: The Definitive Guide").
+ Added makefile.beo for BEOS on X86, contributed by Sander Stok.
+
+Version 1.0.3b [August 26, 1999]
+ Replaced 2147483647L several places with PNG_MAX_UINT macro, defined in png.h
+ Changed leading blanks to tabs in all makefiles.
+ Define PNG_USE_PNGVCRD in makefile.w32, to get MMX assembler code.
+ Made alternate versions of png_set_expand() in pngrtran.c, namely
+ png_set_gray_1_2_4_to_8, png_set_palette_to_rgb, and png_set_tRNS_to_alpha
+ (Greg Roelofs, in "PNG: The Definitive Guide"). Deleted the 1.0.3a aliases.
+ Relocated start of 'extern "C"' block in png.h so it doesn't include pngconf.h
+ Revised calculation of num_blocks in pngmem.c to avoid a potentially
+ negative shift distance, whose results are undefined in the C language.
+ Added a check in pngset.c to prevent writing multiple tIME chunks.
+ Added a check in pngwrite.c to detect invalid small window_bits sizes.
+
+Version 1.0.3d [September 4, 1999]
+ Fixed type casting of igamma in pngrutil.c
+ Added new png_expand functions to scripts/pngdef.pas and pngos2.def
+ Added a demo read_user_transform_fn that examines the row filters in pngtest.c
+
+Version 1.0.4 [September 24, 1999, not distributed publicly]
+ Define PNG_ALWAYS_EXTERN in pngconf.h if __STDC__ is defined
+ Delete #define PNG_INTERNAL and include "png.h" from pngasmrd.h
+ Made several minor corrections to pngtest.c
+ Renamed the makefiles with longer but more user friendly extensions.
+ Copied the PNG copyright and license to a separate LICENSE file.
+ Revised documentation, png.h, and example.c to remove reference to
+ "viewing_gamma" which no longer appears in the PNG specification.
+ Revised pngvcrd.c to use MMX code for interlacing only on the final pass.
+ Updated pngvcrd.c to use the faster C filter algorithms from libpng-1.0.1a
+ Split makefile.win32vc into two versions, makefile.vcawin32 (uses MMX
+ assembler code) and makefile.vcwin32 (doesn't).
+ Added a CPU timing report to pngtest.c (enabled by defining PNGTEST_TIMING)
+ Added a copy of pngnow.png to the distribution.
+
+Version 1.0.4a [September 25, 1999]
+ Increase max_pixel_depth in pngrutil.c if a user transform needs it.
+ Changed several division operations to right-shifts in pngvcrd.c
+
+Version 1.0.4b [September 30, 1999]
+ Added parentheses in line 3732 of pngvcrd.c
+ Added a comment in makefile.linux warning about buggy -O3 in pgcc 2.95.1
+
+Version 1.0.4c [October 1, 1999]
+ Added a "png_check_version" function in png.c and pngtest.c that will generate
+ a helpful compiler error if an old png.h is found in the search path.
+ Changed type of png_user_transform_depth|channels from int to png_byte.
+ Added "Libpng is OSI Certified Open Source Software" statement to png.h
+
+Version 1.0.4d [October 6, 1999]
+ Changed 0.45 to 0.45455 in png_set_sRGB()
+ Removed unused PLTE entries from pngnow.png
+ Re-enabled some parts of pngvcrd.c (png_combine_row) that work properly.
+
+Version 1.0.4e [October 10, 1999]
+ Fixed sign error in pngvcrd.c (Greg Roelofs)
+ Replaced some instances of memcpy with simple assignments in pngvcrd (GR-P)
+
+Version 1.0.4f [October 15, 1999]
+ Surrounded example.c code with #if 0 .. #endif to prevent people from
+ inadvertently trying to compile it.
+ Changed png_get_header_version() from a function to a macro in png.h
+ Added type casting mostly in pngrtran.c and pngwtran.c
+ Removed some pointless "ptr = NULL" in pngmem.c
+ Added a "contrib" directory containing the source code from Greg's book.
+
+Version 1.0.5 [October 15, 1999]
+ Minor editing of the INSTALL and README files.
+
+Version 1.0.5a [October 23, 1999]
+ Added contrib/pngsuite and contrib/pngminus (Willem van Schaik)
+ Fixed a typo in the png_set_sRGB() function call in example.c (Jan Nijtmans)
+ Further optimization and bugfix of pngvcrd.c
+ Revised pngset.c so that it does not allocate or free memory in the user's
+ text_ptr structure. Instead, it makes its own copy.
+ Created separate write_end_info_struct in pngtest.c for a more severe test.
+ Added code in pngwrite.c to free info_ptr->text[i].key to stop a memory leak.
+
+Version 1.0.5b [November 23, 1999]
+ Moved PNG_FLAG_HAVE_CHUNK_HEADER, PNG_FLAG_BACKGROUND_IS_GRAY and
+ PNG_FLAG_WROTE_tIME from flags to mode.
+ Added png_write_info_before_PLTE() function.
+ Fixed some typecasting in contrib/gregbook/*.c
+ Updated scripts/makevms.com and added makevms.com to contrib/gregbook
+ and contrib/pngminus (Martin Zinser)
+
+Version 1.0.5c [November 26, 1999]
+ Moved png_get_header_version from png.h to png.c, to accommodate ansi2knr.
+ Removed all global arrays (according to PNG_NO_GLOBAL_ARRAYS macro), to
+ accommodate making DLL's: Moved usr_png_ver from global variable to function
+ png_get_header_ver() in png.c. Moved png_sig to png_sig_bytes in png.c and
+ eliminated use of png_sig in pngwutil.c. Moved the various png_CHNK arrays
+ into pngtypes.h. Eliminated use of global png_pass arrays. Declared the
+ png_CHNK and png_pass arrays to be "const". Made the global arrays
+ available to applications (although none are used in libpng itself) when
+ PNG_NO_GLOBAL_ARRAYS is not defined or when PNG_GLOBAL_ARRAYS is defined.
+ Removed some extraneous "-I" from contrib/pngminus/makefile.std
+ Changed the PNG_sRGB_INTENT macros in png.h to be consistent with PNG-1.2.
+ Change PNG_SRGB_INTENT to PNG_sRGB_INTENT in libpng.txt and libpng.3
+
+Version 1.0.5d [November 29, 1999]
+ Add type cast (png_const_charp) two places in png.c
+ Eliminated pngtypes.h; use macros instead to declare PNG_CHNK arrays.
+ Renamed "PNG_GLOBAL_ARRAYS" to "PNG_USE_GLOBAL_ARRAYS" and made available
+ to applications a macro "PNG_USE_LOCAL_ARRAYS".
+ comment out (with #ifdef) all the new declarations when
+ PNG_USE_GLOBAL_ARRAYS is defined.
+ Added PNG_EXPORT_VAR macro to accommodate making DLL's.
+
+Version 1.0.5e [November 30, 1999]
+ Added iCCP, iTXt, and sPLT support; added "lang" member to the png_text
+ structure; refactored the inflate/deflate support to make adding new chunks
+ with trailing compressed parts easier in the future, and added new functions
+ png_free_iCCP, png_free_pCAL, png_free_sPLT, png_free_text, png_get_iCCP,
+ png_get_spalettes, png_set_iCCP, png_set_spalettes (Eric S. Raymond).
+ NOTE: Applications that write text chunks MUST define png_text->lang
+ before calling png_set_text(). It must be set to NULL if you want to
+ write tEXt or zTXt chunks. If you want your application to be able to
+ run with older versions of libpng, use
+
+ #ifdef PNG_iTXt_SUPPORTED
+ png_text[i].lang = NULL;
+ #endif
+
+ Changed png_get_oFFs() and png_set_oFFs() to use signed rather than unsigned
+ offsets (Eric S. Raymond).
+ Combined PNG_READ_cHNK_SUPPORTED and PNG_WRITE_cHNK_SUPPORTED macros into
+ PNG_cHNK_SUPPORTED and combined the three types of PNG_text_SUPPORTED
+ macros, leaving the separate macros also available.
+ Removed comments on #endifs at the end of many short, non-nested #if-blocks.
+
+Version 1.0.5f [December 6, 1999]
+ Changed makefile.solaris to issue a warning about potential problems when
+ the ucb "ld" is in the path ahead of the ccs "ld".
+ Removed "- [date]" from the "synopsis" line in libpng.3 and libpngpf.3.
+ Added sCAL chunk support (Eric S. Raymond).
+
+Version 1.0.5g [December 7, 1999]
+ Fixed "png_free_spallettes" typo in png.h
+ Added code to handle new chunks in pngpread.c
+ Moved PNG_CHNK string macro definitions outside of PNG_NO_EXTERN block
+ Added "translated_key" to png_text structure and png_write_iTXt().
+ Added code in pngwrite.c to work around a newly discovered zlib bug.
+
+Version 1.0.5h [December 10, 1999]
+ NOTE: regarding the note for version 1.0.5e, the following must also
+ be included in your code:
+ png_text[i].translated_key = NULL;
+ Unknown chunk handling is now supported.
+ Option to eliminate all floating point support was added. Some new
+ fixed-point functions such as png_set_gAMA_fixed() were added.
+ Expanded tabs and removed trailing blanks in source files.
+
+Version 1.0.5i [December 13, 1999]
+ Added some type casts to silence compiler warnings.
+ Renamed "png_free_spalette" to "png_free_spalettes" for consistency.
+ Removed leading blanks from a #define in pngvcrd.c
+ Added some parameters to the new png_set_keep_unknown_chunks() function.
+ Added a test for up->location != 0 in the first instance of writing
+ unknown chunks in pngwrite.c
+ Changed "num" to "i" in png_free_spalettes() and png_free_unknowns() to
+ prevent recursion.
+ Added png_free_hIST() function.
+ Various patches to fix bugs in the sCAL and integer cHRM processing,
+ and to add some convenience macros for use with sCAL.
+
+Version 1.0.5j [December 21, 1999]
+ Changed "unit" parameter of png_write_sCAL from png_byte to int, to work
+ around buggy compilers.
+ Added new type "png_fixed_point" for integers that hold float*100000 values
+ Restored backward compatibility of tEXt/zTXt chunk processing:
+ Restored the first four members of png_text to the same order as v.1.0.5d.
+ Added members "lang_key" and "itxt_length" to png_text struct. Set
+ text_length=0 when "text" contains iTXt data. Use the "compression"
+ member to distinguish among tEXt/zTXt/iTXt types. Added
+ PNG_ITXT_COMPRESSION_NONE (1) and PNG_ITXT_COMPRESSION_zTXt(2) macros.
+ The "Note" above, about backward incompatibility of libpng-1.0.5e, no
+ longer applies.
+ Fixed png_read|write_iTXt() to read|write parameters in the right order,
+ and to write the iTXt chunk after IDAT if it appears in the end_ptr.
+ Added pnggccrd.c, version of pngvcrd.c Intel assembler for gcc (Greg Roelofs)
+ Reversed the order of trying to write floating-point and fixed-point gAMA.
+
+Version 1.0.5k [December 27, 1999]
+ Added many parentheses, e.g., "if (a && b & c)" becomes "if (a && (b & c))"
+ Added png_handle_as_unknown() function (Glenn)
+ Added png_free_chunk_list() function and chunk_list and num_chunk_list members
+ of png_ptr.
+ Eliminated erroneous warnings about multiple sPLT chunks and sPLT-after-PLTE.
+ Fixed a libpng-1.0.5h bug in pngrutil.c that was issuing erroneous warnings
+ about ignoring incorrect gAMA with sRGB (gAMA was in fact not ignored)
+ Added png_free_tRNS(); png_set_tRNS() now malloc's its own trans array (ESR).
+ Define png_get_int_32 when oFFs chunk is supported as well as when pCAL is.
+ Changed type of proflen from png_int_32 to png_uint_32 in png_get_iCCP().
+
+Version 1.0.5l [January 1, 2000]
+ Added functions png_set_read_user_chunk_fn() and png_get_user_chunk_ptr()
+ for setting a callback function to handle unknown chunks and for
+ retrieving the associated user pointer (Glenn).
+
+Version 1.0.5m [January 7, 2000]
+ Added high-level functions png_read_png(), png_write_png(), png_free_pixels().
+
+Version 1.0.5n [January 9, 2000]
+ Added png_free_PLTE() function, and modified png_set_PLTE() to malloc its
+ own memory for info_ptr->palette. This makes it safe for the calling
+ application to free its copy of the palette any time after it calls
+ png_set_PLTE().
+
+Version 1.0.5o [January 20, 2000]
+ Cosmetic changes only (removed some trailing blanks and TABs)
+
+Version 1.0.5p [January 31, 2000]
+ Renamed pngdll.mak to makefile.bd32
+ Cosmetic changes in pngtest.c
+
+Version 1.0.5q [February 5, 2000]
+ Relocated the makefile.solaris warning about PATH problems.
+ Fixed pngvcrd.c bug by pushing/popping registers in mmxsupport (Bruce Oberg)
+ Revised makefile.gcmmx
+ Added PNG_SETJMP_SUPPORTED, PNG_SETJMP_NOT_SUPPORTED, and PNG_ABORT() macros
+
+Version 1.0.5r [February 7, 2000]
+ Removed superfluous prototype for png_get_itxt from png.h
+ Fixed a bug in pngrtran.c that improperly expanded the background color.
+ Return *num_text=0 from png_get_text() when appropriate, and fix documentation
+ of png_get_text() in libpng.txt/libpng.3.
+
+Version 1.0.5s [February 18, 2000]
+ Added "png_jmp_env()" macro to pngconf.h, to help people migrate to the
+ new error handler that's planned for the next libpng release, and changed
+ example.c, pngtest.c, and contrib programs to use this macro.
+ Revised some of the DLL-export macros in pngconf.h (Greg Roelofs)
+ Fixed a bug in png_read_png() that caused it to fail to expand some images
+ that it should have expanded.
+ Fixed some mistakes in the unused and undocumented INCH_CONVERSIONS functions
+ in pngget.c
+ Changed the allocation of palette, history, and trans arrays back to
+ the version 1.0.5 method (linking instead of copying) which restores
+ backward compatibility with version 1.0.5. Added some remarks about
+ that in example.c. Added "free_me" member to info_ptr and png_ptr
+ and added png_free_data() function.
+ Updated makefile.linux and makefile.gccmmx to make directories conditionally.
+ Made cosmetic changes to pngasmrd.h
+ Added png_set_rows() and png_get_rows(), for use with png_read|write_png().
+ Modified png_read_png() to allocate info_ptr->row_pointers only if it
+ hasn't already been allocated.
+
+Version 1.0.5t [March 4, 2000]
+ Changed png_jmp_env() migration aiding macro to png_jmpbuf().
+ Fixed "interlace" typo (should be "interlaced") in contrib/gregbook/read2-x.c
+ Fixed bug with use of PNG_BEFORE_IHDR bit in png_ptr->mode, introduced when
+ PNG_FLAG_HAVE_CHUNK_HEADER was moved into png_ptr->mode in version 1.0.5b
+ Files in contrib/gregbook were revised to use png_jmpbuf() and to select
+ a 24-bit visual if one is available, and to allow abbreviated options.
+ Files in contrib/pngminus were revised to use the png_jmpbuf() macro.
+ Removed spaces in makefile.linux and makefile.gcmmx, introduced in 1.0.5s
+
+Version 1.0.5u [March 5, 2000]
+ Simplified the code that detects old png.h in png.c and pngtest.c
+ Renamed png_spalette (_p, _pp) to png_sPLT_t (_tp, _tpp)
+ Increased precision of rgb_to_gray calculations from 8 to 15 bits and
+ added png_set_rgb_to_gray_fixed() function.
+ Added makefile.bc32 (32-bit Borland C++, C mode)
+
+Version 1.0.5v [March 11, 2000]
+ Added some parentheses to the png_jmpbuf macro definition.
+ Updated references to the zlib home page, which has moved to freesoftware.com.
+ Corrected bugs in documentation regarding png_read_row() and png_write_row().
+ Updated documentation of png_rgb_to_gray calculations in libpng.3/libpng.txt.
+ Renamed makefile.borland,turboc3 back to makefile.bor,tc3 as in version 1.0.3,
+ revised borland makefiles; added makefile.ibmvac3 and makefile.gcc (Cosmin)
+
+Version 1.0.6 [March 20, 2000]
+ Minor revisions of makefile.bor, libpng.txt, and gregbook/rpng2-win.c
+ Added makefile.sggcc (SGI IRIX with gcc)
+
+Version 1.0.6d [April 7, 2000]
+ Changed sprintf() to strcpy() in png_write_sCAL_s() to work without STDIO
+ Added data_length parameter to png_decompress_chunk() function
+ Revised documentation to remove reference to abandoned png_free_chnk functions
+ Fixed an error in png_rgb_to_gray_fixed()
+ Revised example.c, usage of png_destroy_write_struct().
+ Renamed makefile.ibmvac3 to makefile.ibmc, added libpng.icc IBM project file
+ Added a check for info_ptr->free_me&PNG_FREE_TEXT when freeing text in png.c
+ Simplify png_sig_bytes() function to remove use of non-ISO-C strdup().
+
+Version 1.0.6e [April 9, 2000]
+ Added png_data_freer() function.
+ In the code that checks for over-length tRNS chunks, added check of
+ info_ptr->num_trans as well as png_ptr->num_trans (Matthias Benckmann)
+ Minor revisions of libpng.txt/libpng.3.
+ Check for existing data and free it if the free_me flag is set, in png_set_*()
+ and png_handle_*().
+ Only define PNG_WEIGHTED_FILTERS_SUPPORTED when PNG_FLOATING_POINT_SUPPORTED
+ is defined.
+ Changed several instances of PNG_NO_CONSOLE_ID to PNG_NO_STDIO in pngrutil.c
+ and mentioned the purposes of the two macros in libpng.txt/libpng.3.
+
+Version 1.0.6f [April 14, 2000]
+ Revised png_set_iCCP() and png_set_rows() to avoid prematurely freeing data.
+ Add checks in png_set_text() for NULL members of the input text structure.
+ Revised libpng.txt/libpng.3.
+ Removed superfluous prototype for png_set_iTXt from png.h
+ Removed "else" from pngread.c, after png_error(), and changed "0" to "length".
+ Changed several png_errors about malformed ancillary chunks to png_warnings.
+
+Version 1.0.6g [April 24, 2000]
+ Added png_pass-* arrays to pnggccrd.c when PNG_USE_LOCAL_ARRAYS is defined.
+ Relocated paragraph about png_set_background() in libpng.3/libpng.txt
+ and other revisions (Matthias Benckmann)
+ Relocated info_ptr->free_me, png_ptr->free_me, and other info_ptr and
+ png_ptr members to restore binary compatibility with libpng-1.0.5
+ (breaks compatibility with libpng-1.0.6).
+
+Version 1.0.6h [April 24, 2000]
+ Changed shared library so-number pattern from 2.x.y.z to xy.z (this builds
+ libpng.so.10 & libpng.so.10.6h instead of libpng.so.2 & libpng.so.2.1.0.6h)
+ This is a temporary change for test purposes.
+
+Version 1.0.6i [May 2, 2000]
+ Rearranged some members at the end of png_info and png_struct, to put
+ unknown_chunks_num and free_me within the original size of the png_structs
+ and free_me, png_read_user_fn, and png_free_fn within the original png_info,
+ because some old applications allocate the structs directly instead of
+ using png_create_*().
+ Added documentation of user memory functions in libpng.txt/libpng.3
+ Modified png_read_png so that it will use user_allocated row_pointers
+ if present, unless free_me directs that it be freed, and added description
+ of the use of png_set_rows() and png_get_rows() in libpng.txt/libpng.3.
+ Added PNG_LEGACY_SUPPORTED macro, and #ifdef out all new (since version
+ 1.00) members of png_struct and png_info, to regain binary compatibility
+ when you define this macro. Capabilities lost in this event
+ are user transforms (new in version 1.0.0),the user transform pointer
+ (new in version 1.0.2), rgb_to_gray (new in 1.0.5), iCCP, sCAL, sPLT,
+ the high-level interface, and unknown chunks support (all new in 1.0.6).
+ This was necessary because of old applications that allocate the structs
+ directly as authors were instructed to do in libpng-0.88 and earlier,
+ instead of using png_create_*().
+ Added modes PNG_CREATED_READ_STRUCT and PNG_CREATED_WRITE_STRUCT which
+ can be used to detect codes that directly allocate the structs, and
+ code to check these modes in png_read_init() and png_write_init() and
+ generate a libpng error if the modes aren't set and PNG_LEGACY_SUPPORTED
+ was not defined.
+ Added makefile.intel and updated makefile.watcom (Pawel Mrochen)
+
+Version 1.0.6j [May 3, 2000]
+ Overloaded png_read_init() and png_write_init() with macros that convert
+ calls to png_read_init_2() or png_write_init_2() that check the version
+ and structure sizes.
+
+Version 1.0.7beta11 [May 7, 2000]
+ Removed the new PNG_CREATED_READ_STRUCT and PNG_CREATED_WRITE_STRUCT modes
+ which are no longer used.
+ Eliminated the three new members of png_text when PNG_LEGACY_SUPPORTED is
+ defined or when neither PNG_READ_iTXt_SUPPORTED nor PNG_WRITE_iTXT_SUPPORTED
+ is defined.
+ Made PNG_NO_READ|WRITE_iTXt the default setting, to avoid memory
+ overrun when old applications fill the info_ptr->text structure directly.
+ Added PNGAPI macro, and added it to the definitions of all exported functions.
+ Relocated version macro definitions ahead of the includes of zlib.h and
+ pngconf.h in png.h.
+
+Version 1.0.7beta12 [May 12, 2000]
+ Revised pngset.c to avoid a problem with expanding the png_debug macro.
+ Deleted some extraneous defines from pngconf.h
+ Made PNG_NO_CONSOLE_IO the default condition when PNG_BUILD_DLL is defined.
+ Use MSC _RPTn debugging instead of fprintf if _MSC_VER is defined.
+ Added png_access_version_number() function.
+ Check for mask&PNG_FREE_CHNK (for TEXT, SCAL, PCAL) in png_free_data().
+ Expanded libpng.3/libpng.txt information about png_data_freer().
+
+Version 1.0.7beta14 [May 17, 2000] (beta13 was not published)
+ Changed pnggccrd.c and pngvcrd.c to handle bad adaptive filter types as
+ warnings instead of errors, as pngrutil.c does.
+ Set the PNG_INFO_IDAT valid flag in png_set_rows() so png_write_png()
+ will actually write IDATs.
+ Made the default PNG_USE_LOCAL_ARRAYS depend on PNG_DLL instead of WIN32.
+ Make png_free_data() ignore its final parameter except when freeing data
+ that can have multiple instances (text, sPLT, unknowns).
+ Fixed a new bug in png_set_rows().
+ Removed info_ptr->valid tests from png_free_data(), as in version 1.0.5.
+ Added png_set_invalid() function.
+ Fixed incorrect illustrations of png_destroy_write_struct() in example.c.
+
+Version 1.0.7beta15 [May 30, 2000]
+ Revised the deliberately erroneous Linux setjmp code in pngconf.h to produce
+ fewer error messages.
+ Rearranged checks for Z_OK to check the most likely path first in pngpread.c
+ and pngwutil.c.
+ Added checks in pngtest.c for png_create_*() returning NULL, and mentioned
+ in libpng.txt/libpng.3 the need for applications to check this.
+ Changed names of png_default_*() functions in pngtest to pngtest_*().
+ Changed return type of png_get_x|y_offset_*() from png_uint_32 to png_int_32.
+ Fixed some bugs in the unused PNG_INCH_CONVERSIONS functions in pngget.c
+ Set each pointer to NULL after freeing it in png_free_data().
+ Worked around a problem in pngconf.h; AIX's strings.h defines an "index"
+ macro that conflicts with libpng's png_color_16.index. (Dimitri
+ Papadapoulos)
+ Added "msvc" directory with MSVC++ project files (Simon-Pierre Cadieux).
+
+Version 1.0.7beta16 [June 4, 2000]
+ Revised the workaround of AIX string.h "index" bug.
+ Added a check for overlength PLTE chunk in pngrutil.c.
+ Added PNG_NO_POINTER_INDEXING macro to use array-indexing instead of pointer
+ indexing in pngrutil.c and pngwutil.c to accommodate a buggy compiler.
+ Added a warning in png_decompress_chunk() when it runs out of data, e.g.
+ when it tries to read an erroneous PhotoShop iCCP chunk.
+ Added PNG_USE_DLL macro.
+ Revised the copyright/disclaimer/license notice.
+ Added contrib/msvctest directory
+
+Version 1.0.7rc1 [June 9, 2000]
+ Corrected the definition of PNG_TRANSFORM_INVERT_ALPHA (0x0400 not 0x0200)
+ Added contrib/visupng directory (Willem van Schaik)
+
+Version 1.0.7beta18 [June 23, 2000]
+ Revised PNGAPI definition, and pngvcrd.c to work with __GCC__
+ and do not redefine PNGAPI if it is passed in via a compiler directive.
+ Revised visupng/PngFile.c to remove returns from within the Try block.
+ Removed leading underscores from "_PNG_H" and "_PNG_SAVE_BSD_SOURCE" macros.
+ Updated contrib/visupng/cexcept.h to version 1.0.0.
+ Fixed bugs in pngwrite.c and pngwutil.c that prevented writing iCCP chunks.
+
+Version 1.0.7rc2 [June 28, 2000]
+ Updated license to include disclaimers required by UCITA.
+ Fixed "DJBPP" typo in pnggccrd.c introduced in beta18.
+
+Version 1.0.7 [July 1, 2000]
+ Revised the definition of "trans_values" in libpng.3/libpng.txt
+
+Version 1.0.8beta1 [July 8, 2000]
+ Added png_free(png_ptr, key) two places in pngpread.c to stop memory leaks.
+ Changed PNG_NO_STDIO to PNG_NO_CONSOLE_IO, several places in pngrutil.c and
+ pngwutil.c.
+ Changed PNG_EXPORT_VAR to use PNG_IMPEXP, in pngconf.h.
+ Removed unused "#include <assert.h>" from png.c
+ Added WindowsCE support.
+ Revised pnggccrd.c to work with gcc-2.95.2 and in the Cygwin environment.
+
+Version 1.0.8beta2 [July 10, 2000]
+ Added project files to the wince directory and made further revisions
+ of pngtest.c, pngrio.c, and pngwio.c in support of WindowsCE.
+
+Version 1.0.8beta3 [July 11, 2000]
+ Only set the PNG_FLAG_FREE_TRNS or PNG_FREE_TRNS flag in png_handle_tRNS()
+ for indexed-color input files to avoid potential double-freeing trans array
+ under some unusual conditions; problem was introduced in version 1.0.6f.
+ Further revisions to pngtest.c and files in the wince subdirectory.
+
+Version 1.0.8beta4 [July 14, 2000]
+ Added the files pngbar.png and pngbar.jpg to the distribution.
+ Added makefile.cygwin, and cygwin support in pngconf.h
+ Added PNG_NO_ZALLOC_ZERO macro (makes png_zalloc skip zeroing memory)
+
+Version 1.0.8rc1 [July 16, 2000]
+ Revised png_debug() macros and statements to eliminate compiler warnings.
+
+Version 1.0.8 [July 24, 2000]
+ Added png_flush() in pngwrite.c, after png_write_IEND().
+ Updated makefile.hpux to build a shared library.
+
+Version 1.0.9beta1 [November 10, 2000]
+ Fixed typo in scripts/makefile.hpux
+ Updated makevms.com in scripts and contrib/* and contrib/* (Martin Zinser)
+ Fixed seqence-point bug in contrib/pngminus/png2pnm (Martin Zinser)
+ Changed "cdrom.com" in documentation to "libpng.org"
+ Revised pnggccrd.c to get it all working, and updated makefile.gcmmx (Greg).
+ Changed type of "params" from voidp to png_voidp in png_read|write_png().
+ Make sure PNGAPI and PNG_IMPEXP are defined in pngconf.h.
+ Revised the 3 instances of WRITEFILE in pngtest.c.
+ Relocated "msvc" and "wince" project subdirectories into "dll" subdirectory.
+ Updated png.rc in dll/msvc project
+ Revised makefile.dec to define and use LIBPATH and INCPATH
+ Increased size of global png_libpng_ver[] array from 12 to 18 chars.
+ Made global png_libpng_ver[], png_sig[] and png_pass_*[] arrays const.
+ Removed duplicate png_crc_finish() from png_handle_bKGD() function.
+ Added a warning when application calls png_read_update_info() multiple times.
+ Revised makefile.cygwin
+ Fixed bugs in iCCP support in pngrutil.c and pngwutil.c.
+ Replaced png_set_empty_plte_permitted() with png_permit_mng_features().
+
+Version 1.0.9beta2 [November 19, 2000]
+ Renamed the "dll" subdirectory "projects".
+ Added borland project files to "projects" subdirectory.
+ Set VS_FF_PRERELEASE and VS_FF_PATCHED flags in msvc/png.rc when appropriate.
+ Add error message in png_set_compression_buffer_size() when malloc fails.
+
+Version 1.0.9beta3 [November 23, 2000]
+ Revised PNG_LIBPNG_BUILD_TYPE macro in png.h, used in the msvc project.
+ Removed the png_flush() in pngwrite.c that crashes some applications
+ that don't set png_output_flush_fn.
+ Added makefile.macosx and makefile.aix to scripts directory.
+
+Version 1.0.9beta4 [December 1, 2000]
+ Change png_chunk_warning to png_warning in png_check_keyword().
+ Increased the first part of msg buffer from 16 to 18 in png_chunk_error().
+
+Version 1.0.9beta5 [December 15, 2000]
+ Added support for filter method 64 (for PNG datastreams embedded in MNG).
+
+Version 1.0.9beta6 [December 18, 2000]
+ Revised png_set_filter() to accept filter method 64 when appropriate.
+ Added new PNG_HAVE_PNG_SIGNATURE bit to png_ptr->mode and use it to
+ help prevent applications from using MNG features in PNG datastreams.
+ Added png_permit_mng_features() function.
+ Revised libpng.3/libpng.txt. Changed "filter type" to "filter method".
+
+Version 1.0.9rc1 [December 23, 2000]
+ Revised test for PNG_HAVE_PNG_SIGNATURE in pngrutil.c
+ Fixed error handling of unknown compression type in png_decompress_chunk().
+ In pngconf.h, define __cdecl when _MSC_VER is defined.
+
+Version 1.0.9beta7 [December 28, 2000]
+ Changed PNG_TEXT_COMPRESSION_zTXt to PNG_COMPRESSION_TYPE_BASE several places.
+ Revised memory management in png_set_hIST and png_handle_hIST in a backward
+ compatible manner. PLTE and tRNS were revised similarly.
+ Revised the iCCP chunk reader to ignore trailing garbage.
+
+Version 1.0.9beta8 [January 12, 2001]
+ Moved pngasmrd.h into pngconf.h.
+ Improved handling of out-of-spec garbage iCCP chunks generated by PhotoShop.
+
+Version 1.0.9beta9 [January 15, 2001]
+ Added png_set_invalid, png_permit_mng_features, and png_mmx_supported to
+ wince and msvc project module definition files.
+ Minor revision of makefile.cygwin.
+ Fixed bug with progressive reading of narrow interlaced images in pngpread.c
+
+Version 1.0.9beta10 [January 16, 2001]
+ Do not typedef png_FILE_p in pngconf.h when PNG_NO_STDIO is defined.
+ Fixed "png_mmx_supported" typo in project definition files.
+
+Version 1.0.9beta11 [January 19, 2001]
+ Updated makefile.sgi to make shared library.
+ Removed png_mmx_support() function and disabled PNG_MNG_FEATURES_SUPPORTED
+ by default, for the benefit of DLL forward compatibility. These will
+ be re-enabled in version 1.2.0.
+
+Version 1.0.9rc2 [January 22, 2001]
+ Revised cygwin support.
+
+Version 1.0.9 [January 31, 2001]
+ Added check of cygwin's ALL_STATIC in pngconf.h
+ Added "-nommx" parameter to contrib/gregbook/rpng2-win and rpng2-x demos.
+
+Version 1.0.10beta1 [March 14, 2001]
+ Revised makefile.dec, makefile.sgi, and makefile.sggcc; added makefile.hpgcc.
+ Reformatted libpng.3 to eliminate bad line breaks.
+ Added checks for _mmx_supported in the read_filter_row function of pnggccrd.c
+ Added prototype for png_mmx_support() near the top of pnggccrd.c
+ Moved some error checking from png_handle_IHDR to png_set_IHDR.
+ Added PNG_NO_READ_SUPPORTED and PNG_NO_WRITE_SUPPORTED macros.
+ Revised png_mmx_support() function in pnggccrd.c
+ Restored version 1.0.8 PNG_WRITE_EMPTY_PLTE_SUPPORTED behavior in pngwutil.c
+ Fixed memory leak in contrib/visupng/PngFile.c
+ Fixed bugs in png_combine_row() in pnggccrd.c and pngvcrd.c (C version)
+ Added warnings when retrieving or setting gamma=0.
+ Increased the first part of msg buffer from 16 to 18 in png_chunk_warning().
+
+Version 1.0.10rc1 [March 23, 2001]
+ Changed all instances of memcpy, strcpy, and strlen to png_memcpy, png_strcpy,
+ and png_strlen.
+ Revised png_mmx_supported() function in pnggccrd.c to return proper value.
+ Fixed bug in progressive reading (pngpread.c) with small images (height < 8).
+
+Version 1.0.10 [March 30, 2001]
+ Deleted extraneous space (introduced in 1.0.9) from line 42 of makefile.cygwin
+ Added beos project files (Chris Herborth)
+
+Version 1.0.11beta1 [April 3, 2001]
+ Added type casts on several png_malloc() calls (Dimitri Papadapoulos).
+ Removed a no-longer needed AIX work-around from pngconf.h
+ Changed several "//" single-line comments to C-style in pnggccrd.c
+
+Version 1.0.11beta2 [April 11, 2001]
+ Removed PNGAPI from several functions whose prototypes did not have PNGAPI.
+ Updated scripts/pngos2.def
+
+Version 1.0.11beta3 [April 14, 2001]
+ Added checking the results of many instances of png_malloc() for NULL
+
+Version 1.0.11beta4 [April 20, 2001]
+ Undid the changes from version 1.0.11beta3. Added a check for NULL return
+ from user's malloc_fn().
+ Removed some useless type casts of the NULL pointer.
+ Added makefile.netbsd
+
+Version 1.0.11 [April 27, 2001]
+ Revised makefile.netbsd
+
+Version 1.0.12beta1 [May 14, 2001]
+ Test for Windows platform in pngconf.h when including malloc.h (Emmanuel Blot)
+ Updated makefile.cygwin and handling of Cygwin's ALL_STATIC in pngconf.h
+ Added some never-to-be-executed code in pnggccrd.c to quiet compiler warnings.
+ Eliminated the png_error about apps using png_read|write_init(). Instead,
+ libpng will reallocate the png_struct and info_struct if they are too small.
+ This retains future binary compatibility for old applications written for
+ libpng-0.88 and earlier.
+
+Version 1.2.0beta1 [May 6, 2001]
+ Bumped DLLNUM to 2.
+ Re-enabled PNG_MNG_FEATURES_SUPPORTED and enabled PNG_ASSEMBLER_CODE_SUPPORTED
+ by default.
+ Added runtime selection of MMX features.
+ Added png_set_strip_error_numbers function and related macros.
+
+Version 1.2.0beta2 [May 7, 2001]
+ Finished merging 1.2.0beta1 with version 1.0.11
+ Added a check for attempts to read or write PLTE in grayscale PNG datastreams.
+
+Version 1.2.0beta3 [May 17, 2001]
+ Enabled user memory function by default.
+ Modified png_create_struct so it passes user mem_ptr to user memory allocator.
+ Increased png_mng_features flag from png_byte to png_uint_32.
+ Bumped shared-library (so-number) and dll-number to 3.
+
+Version 1.2.0beta4 [June 23, 2001]
+ Check for missing profile length field in iCCP chunk and free chunk_data
+ in case of truncated iCCP chunk.
+ Bumped shared-library number to 3 in makefile.sgi and makefile.sggcc
+ Bumped dll-number from 2 to 3 in makefile.cygwin
+ Revised contrib/gregbook/rpng*-x.c to avoid a memory leak and to exit cleanly
+ if user attempts to run it on an 8-bit display.
+ Updated contrib/gregbook
+ Use png_malloc instead of png_zalloc to allocate palette in pngset.c
+ Updated makefile.ibmc
+ Added some typecasts to eliminate gcc 3.0 warnings. Changed prototypes
+ of png_write_oFFS width and height from png_uint_32 to png_int_32.
+ Updated example.c
+ Revised prototypes for png_debug_malloc and png_debug_free in pngtest.c
+
+Version 1.2.0beta5 [August 8, 2001]
+ Revised contrib/gregbook
+ Revised makefile.gcmmx
+ Revised pnggccrd.c to conditionally compile some thread-unsafe code only
+ when PNG_THREAD_UNSAFE_OK is defined.
+ Added tests to prevent pngwutil.c from writing a bKGD or tRNS chunk with
+ value exceeding 2^bit_depth-1
+ Revised makefile.sgi and makefile.sggcc
+ Replaced calls to fprintf(stderr,...) with png_warning() in pnggccrd.c
+ Removed restriction that do_invert_mono only operate on 1-bit opaque files
+
+Version 1.2.0 [September 1, 2001]
+ Changed a png_warning() to png_debug() in pnggccrd.c
+ Fixed contrib/gregbook/rpng-x.c, rpng2-x.c to avoid crash with XFreeGC().
+
+Version 1.2.1beta1 [October 19, 2001]
+ Revised makefile.std in contrib/pngminus
+ Include background_1 in png_struct regardless of gamma support.
+ Revised makefile.netbsd and makefile.macosx, added makefile.darwin.
+ Revised example.c to provide more details about using row_callback().
+
+Version 1.2.1beta2 [October 25, 2001]
+ Added type cast to each NULL appearing in a function call, except for
+ WINCE functions.
+ Added makefile.so9.
+
+Version 1.2.1beta3 [October 27, 2001]
+ Removed type casts from all NULLs.
+ Simplified png_create_struct_2().
+
+Version 1.2.1beta4 [November 7, 2001]
+ Revised png_create_info_struct() and png_creat_struct_2().
+ Added error message if png_write_info() was omitted.
+ Type cast NULLs appearing in function calls when _NO_PROTO or
+ PNG_TYPECAST_NULL is defined.
+
+Version 1.2.1rc1 [November 24, 2001]
+ Type cast NULLs appearing in function calls except when PNG_NO_TYPECAST_NULL
+ is defined.
+ Changed typecast of "size" argument to png_size_t in pngmem.c calls to
+ the user malloc_fn, to agree with the prototype in png.h
+ Added a pop/push operation to pnggccrd.c, to preserve Eflag (Maxim Sobolev)
+ Updated makefile.sgi to recognize LIBPATH and INCPATH.
+ Updated various makefiles so "make clean" does not remove previous major
+ version of the shared library.
+
+Version 1.2.1rc2 [December 4, 2001]
+ Always allocate 256-entry internal palette, hist, and trans arrays, to
+ avoid out-of-bounds memory reference caused by invalid PNG datastreams.
+ Added a check for prefix_length > data_length in iCCP chunk handler.
+
+Version 1.2.1 [December 7, 2001]
+ None.
+
+Version 1.2.2beta1 [February 22, 2002]
+ Fixed a bug with reading the length of iCCP profiles (Larry Reeves).
+ Revised makefile.linux, makefile.gcmmx, and makefile.sgi to generate
+ libpng.a, libpng12.so (not libpng.so.3), and libpng12/png.h
+ Revised makefile.darwin to remove "-undefined suppress" option.
+ Added checks for gamma and chromaticity values over 21474.83, which exceed
+ the limit for PNG unsigned 32-bit integers when encoded.
+ Revised calls to png_create_read_struct() and png_create_write_struct()
+ for simpler debugging.
+ Revised png_zalloc() so zlib handles errors (uses PNG_FLAG_MALLOC_NULL_MEM_OK)
+
+Version 1.2.2beta2 [February 23, 2002]
+ Check chunk_length and idat_size for invalid (over PNG_MAX_UINT) lengths.
+ Check for invalid image dimensions in png_get_IHDR.
+ Added missing "fi;" in the install target of the SGI makefiles.
+ Added install-static to all makefiles that make shared libraries.
+ Always do gamma compensation when image is partially transparent.
+
+Version 1.2.2beta3 [March 7, 2002]
+ Compute background.gray and background_1.gray even when color_type is RGB
+ in case image gets reduced to gray later.
+ Modified shared-library makefiles to install pkgconfig/libpngNN.pc.
+ Export (with PNGAPI) png_zalloc, png_zfree, and png_handle_as_unknown
+ Removed unused png_write_destroy_info prototype from png.h
+ Eliminated incorrect use of width_mmx from pnggccrd.c in pixel_bytes == 8 case
+ Added install-shared target to all makefiles that make shared libraries.
+ Stopped a double free of palette, hist, and trans when not using free_me.
+ Added makefile.32sunu for Sun Ultra 32 and makefile.64sunu for Sun Ultra 64.
+
+Version 1.2.2beta4 [March 8, 2002]
+ Compute background.gray and background_1.gray even when color_type is RGB
+ in case image gets reduced to gray later (Jason Summers).
+ Relocated a misplaced /bin/rm in the "install-shared" makefile targets
+ Added PNG_1_0_X macro which can be used to build a 1.0.x-compatible library.
+
+Version 1.2.2beta5 [March 26, 2002]
+ Added missing PNGAPI to several function definitions.
+ Check for invalid bit_depth or color_type in png_get_IHDR(), and
+ check for missing PLTE or IHDR in png_push_read_chunk() (Matthias Clasen).
+ Revised iTXt support to accept NULL for lang and lang_key.
+ Compute gamma for color components of background even when color_type is gray.
+ Changed "()" to "{}" in scripts/libpng.pc.in.
+ Revised makefiles to put png.h and pngconf.h only in $prefix/include/libpngNN
+ Revised makefiles to make symlink to libpng.so.NN in addition to libpngNN.so
+
+Version 1.2.2beta6 [March 31, 2002]
+
+Version 1.0.13beta1 [March 31, 2002]
+ Prevent png_zalloc() from trying to memset memory that it failed to acquire.
+ Add typecasts of PNG_MAX_UINT in pngset_cHRM_fixed() (Matt Holgate).
+ Ensure that the right function (user or default) is used to free the
+ png_struct after an error in png_create_read_struct_2().
+
+Version 1.2.2rc1 [April 7, 2002]
+
+Version 1.0.13rc1 [April 7, 2002]
+ Save the ebx register in pnggccrd.c (Sami Farin)
+ Add "mem_ptr = png_ptr->mem_ptr" in png_destroy_write_struct() (Paul Gardner).
+ Updated makefiles to put headers in include/libpng and remove old include/*.h.
+
+Version 1.2.2 [April 15, 2002]
+
+Version 1.0.13 [April 15, 2002]
+ Revised description of png_set_filter() in libpng.3/libpng.txt.
+ Revised makefile.netbsd and added makefile.neNNbsd and makefile.freebsd
+
+Version 1.0.13patch01 [April 17, 2002]
+
+Version 1.2.2patch01 [April 17, 2002]
+ Changed ${PNGMAJ}.${PNGVER} bug to ${PNGVER} in makefile.sgi and
+ makefile.sggcc
+ Fixed VER -> PNGVER typo in makefile.macosx and added install-static to
+ install
+ Added install: target to makefile.32sunu and makefile.64sunu
+
+Version 1.0.13patch03 [April 18, 2002]
+
+Version 1.2.2patch03 [April 18, 2002]
+ Revised 15 makefiles to link libpng.a to libpngNN.a and the include libpng
+ subdirectory to libpngNN subdirectory without the full pathname.
+ Moved generation of libpng.pc from "install" to "all" in 15 makefiles.
+
+Version 1.2.3rc1 [April 28, 2002]
+ Added install-man target to 15 makefiles (Dimitri Papadopolous-Orfanos).
+ Added $(DESTDIR) feature to 24 makefiles (Tim Mooney)
+ Fixed bug with $prefix, should be $(prefix) in makefile.hpux.
+ Updated cygwin-specific portion of pngconf.h and revised makefile.cygwin
+ Added a link from libpngNN.pc to libpng.pc in 15 makefiles.
+ Added links from include/libpngNN/*.h to include/*.h in 24 makefiles.
+ Revised makefile.darwin to make relative links without full pathname.
+ Added setjmp() at the end of png_create_*_struct_2() in case user forgets
+ to put one in their application.
+ Restored png_zalloc() and png_zfree() prototypes to version 1.2.1 and
+ removed them from module definition files.
+
+Version 1.2.3rc2 [May 1, 2002]
+ Fixed bug in reporting number of channels in pngget.c and pngset.c,
+ that was introduced in version 1.2.2beta5.
+ Exported png_zalloc(), png_zfree(), png_default_read(), png_default_write(),
+ png_default_flush(), and png_push_fill_buffer() and included them in
+ module definition files.
+ Added "libpng.pc" dependency to the "install-shared" target in 15 makefiles.
+
+Version 1.2.3rc3 [May 1, 2002]
+ Revised prototype for png_default_flush()
+ Remove old libpng.pc and libpngNN.pc before installing new ones.
+
+Version 1.2.3rc4 [May 2, 2002]
+ Typos in *.def files (png_default_read|write -> png_default_read|write_data)
+ In makefiles, changed rm libpng.NN.pc to rm libpngNN.pc
+ Added libpng-config and libpngNN-config and modified makefiles to install
+ them.
+ Changed $(MANPATH) to $(DESTDIR)$(MANPATH) in makefiles
+ Added "Win32 DLL VB" configuration to projects/msvc/libpng.dsp
+
+Version 1.2.3rc5 [May 11, 2002]
+ Changed "error" and "message" in prototypes to "error_message" and
+ "warning_message" to avoid namespace conflict.
+ Revised 15 makefiles to build libpng-config from libpng-config-*.in
+ Once more restored png_zalloc and png_zfree to regular nonexported form.
+ Restored png_default_read|write_data, png_default_flush, png_read_fill_buffer
+ to nonexported form, but with PNGAPI, and removed them from module def
+ files.
+
+Version 1.2.3rc6 [May 14, 2002]
+ Removed "PNGAPI" from png_zalloc() and png_zfree() in png.c
+ Changed "Gz" to "Gd" in projects/msvc/libpng.dsp and zlib.dsp.
+ Removed leftover libpng-config "sed" script from four makefiles.
+ Revised libpng-config creating script in 16 makefiles.
+
+Version 1.2.3 [May 22, 2002]
+ Revised libpng-config target in makefile.cygwin.
+ Removed description of png_set_mem_fn() from documentation.
+ Revised makefile.freebsd.
+ Minor cosmetic changes to 15 makefiles, e.g., $(DI) = $(DESTDIR)/$(INCDIR).
+ Revised projects/msvc/README.txt
+ Changed -lpng to -lpngNN in LDFLAGS in several makefiles.
+
+Version 1.2.4beta1 [May 24, 2002]
+ Added libpng.pc and libpng-config to "all:" target in 16 makefiles.
+ Fixed bug in 16 makefiles: $(DESTDIR)/$(LIBPATH) to $(DESTDIR)$(LIBPATH)
+ Added missing "\" before closing double quote in makefile.gcmmx.
+ Plugged various memory leaks; added png_malloc_warn() and png_set_text_2()
+ functions.
+
+Version 1.2.4beta2 [June 25, 2002]
+ Plugged memory leak of png_ptr->current_text (Matt Holgate).
+ Check for buffer overflow before reading CRC in pngpread.c (Warwick Allison)
+ Added -soname to the loader flags in makefile.dec, makefile.sgi, and
+ makefile.sggcc.
+ Added "test-installed" target to makefile.linux, makefile.gcmmx,
+ makefile.sgi, and makefile.sggcc.
+
+Version 1.2.4beta3 [June 28, 2002]
+ Plugged memory leak of row_buf in pngtest.c when there is a png_error().
+ Detect buffer overflow in pngpread.c when IDAT is corrupted with extra data.
+ Added "test-installed" target to makefile.32sunu, makefile.64sunu,
+ makefile.beos, makefile.darwin, makefile.dec, makefile.macosx,
+ makefile.solaris, makefile.hpux, makefile.hpgcc, and makefile.so9.
+
+Version 1.2.4rc1 and 1.0.14rc1 [July 2, 2002]
+ Added "test-installed" target to makefile.cygwin and makefile.sco.
+ Revised pnggccrd.c to be able to back out version 1.0.x via PNG_1_0_X macro.
+
+Version 1.2.4 and 1.0.14 [July 8, 2002]
+ Changed png_warning() to png_error() when width is too large to process.
+
+Version 1.2.4patch01 [July 20, 2002]
+ Revised makefile.cygwin to use DLL number 12 instead of 13.
+
+Version 1.2.5beta1 [August 6, 2002]
+ Added code to contrib/gregbook/readpng2.c to ignore unused chunks.
+ Replaced toucan.png in contrib/gregbook (it has been corrupt since 1.0.11)
+ Removed some stray *.o files from contrib/gregbook.
+ Changed png_error() to png_warning() about "Too much data" in pngpread.c
+ and about "Extra compressed data" in pngrutil.c.
+ Prevent png_ptr->pass from exceeding 7 in png_push_finish_row().
+ Updated makefile.hpgcc
+ Updated png.c and pnggccrd.c handling of return from png_mmx_support()
+
+Version 1.2.5beta2 [August 15, 2002]
+ Only issue png_warning() about "Too much data" in pngpread.c when avail_in
+ is nonzero.
+ Updated makefiles to install a separate libpng.so.3 with its own rpath.
+
+Version 1.2.5rc1 and 1.0.15rc1 [August 24, 2002]
+ Revised makefiles to not remove previous minor versions of shared libraries.
+
+Version 1.2.5rc2 and 1.0.15rc2 [September 16, 2002]
+ Revised 13 makefiles to remove "-lz" and "-L$(ZLIBLIB)", etc., from shared
+ library loader directive.
+ Added missing "$OBJSDLL" line to makefile.gcmmx.
+ Added missing "; fi" to makefile.32sunu.
+
+Version 1.2.5rc3 and 1.0.15rc3 [September 18, 2002]
+ Revised libpng-config script.
+
+Version 1.2.5 and 1.0.15 [October 3, 2002]
+ Revised makefile.macosx, makefile.darwin, makefile.hpgcc, and makefile.hpux,
+ and makefile.aix.
+ Relocated two misplaced PNGAPI lines in pngtest.c
+
+Version 1.2.6beta1 [October 22, 2002]
+ Commented out warning about uninitialized mmx_support in pnggccrd.c.
+ Changed "IBMCPP__" flag to "__IBMCPP__" in pngconf.h.
+ Relocated two more misplaced PNGAPI lines in pngtest.c
+ Fixed memory overrun bug in png_do_read_filler() with 16-bit datastreams,
+ introduced in version 1.0.2.
+ Revised makefile.macosx, makefile.dec, makefile.aix, and makefile.32sunu.
+
+Version 1.2.6beta2 [November 1, 2002]
+ Added libpng-config "--ldopts" output.
+ Added "AR=ar" and "ARFLAGS=rc" and changed "ar rc" to "$(AR) $(ARFLAGS)"
+ in makefiles.
+
+Version 1.2.6beta3 [July 18, 2004]
+ Reverted makefile changes from version 1.2.6beta2 and some of the changes
+ from version 1.2.6beta1; these will be postponed until version 1.2.7.
+ Version 1.2.6 is going to be a simple bugfix release.
+ Changed the one instance of "ln -sf" to "ln -f -s" in each Sun makefile.
+ Fixed potential overrun in pngerror.c by using strncpy instead of memcpy.
+ Added "#!/bin/sh" at the top of configure, for recognition of the
+ 'x' flag under Cygwin (Cosmin).
+ Optimized vacuous tests that silence compiler warnings, in png.c (Cosmin).
+ Added support for PNG_USER_CONFIG, in pngconf.h (Cosmin).
+ Fixed the special memory handler for Borland C under DOS, in pngmem.c
+ (Cosmin).
+ Removed some spurious assignments in pngrutil.c (Cosmin).
+ Replaced 65536 with 65536L, and 0xffff with 0xffffL, to silence warnings
+ on 16-bit platforms (Cosmin).
+ Enclosed shift op expressions in parentheses, to silence warnings (Cosmin).
+ Used proper type png_fixed_point, to avoid problems on 16-bit platforms,
+ in png_handle_sRGB() (Cosmin).
+ Added compression_type to png_struct, and optimized the window size
+ inside the deflate stream (Cosmin).
+ Fixed definition of isnonalpha(), in pngerror.c and pngrutil.c (Cosmin).
+ Fixed handling of unknown chunks that come after IDAT (Cosmin).
+ Allowed png_error() and png_warning() to work even if png_ptr == NULL
+ (Cosmin).
+ Replaced row_info->rowbytes with row_bytes in png_write_find_filter()
+ (Cosmin).
+ Fixed definition of PNG_LIBPNG_VER_DLLNUM (Simon-Pierre).
+ Used PNG_LIBPNG_VER and PNG_LIBPNG_VER_STRING instead of the hardcoded
+ values in png.c (Simon-Pierre, Cosmin).
+ Initialized png_libpng_ver[] with PNG_LIBPNG_VER_STRING (Simon-Pierre).
+ Replaced PNG_LIBPNG_VER_MAJOR with PNG_LIBPNG_VER_DLLNUM in png.rc
+ (Simon-Pierre).
+ Moved the definition of PNG_HEADER_VERSION_STRING near the definitions
+ of the other PNG_LIBPNG_VER_... symbols in png.h (Cosmin).
+ Relocated #ifndef PNGAPI guards in pngconf.h (Simon-Pierre, Cosmin).
+ Updated scripts/makefile.vc(a)win32 (Cosmin).
+ Updated the MSVC project (Simon-Pierre, Cosmin).
+ Updated the Borland C++ Builder project (Cosmin).
+ Avoided access to asm_flags in pngvcrd.c, if PNG_1_0_X is defined (Cosmin).
+ Commented out warning about uninitialized mmx_support in pngvcrd.c (Cosmin).
+ Removed scripts/makefile.bd32 and scripts/pngdef.pas (Cosmin).
+ Added extra guard around inclusion of Turbo C memory headers, in pngconf.h
+ (Cosmin).
+ Renamed projects/msvc/ to projects/visualc6/, and projects/borland/ to
+ projects/cbuilder5/ (Cosmin).
+ Moved projects/visualc6/png32ms.def to scripts/pngw32.def,
+ and projects/visualc6/png.rc to scripts/pngw32.rc (Cosmin).
+ Added projects/visualc6/pngtest.dsp; removed contrib/msvctest/ (Cosmin).
+ Changed line endings to DOS style in cbuilder5 and visualc6 files, even
+ in the tar.* distributions (Cosmin).
+ Updated contrib/visupng/VisualPng.dsp (Cosmin).
+ Updated contrib/visupng/cexcept.h to version 2.0.0 (Cosmin).
+ Added a separate distribution with "configure" and supporting files (Junichi).
+
+Version 1.2.6beta4 [July 28, 2004]
+ Added user ability to change png_size_t via a PNG_SIZE_T macro.
+ Added png_sizeof() and png_convert_size() functions.
+ Added PNG_SIZE_MAX (maximum value of a png_size_t variable.
+ Added check in png_malloc_default() for (size_t)size != (png_uint_32)size
+ which would indicate an overflow.
+ Changed sPLT failure action from png_error to png_warning and abandon chunk.
+ Changed sCAL and iCCP failures from png_error to png_warning and abandon.
+ Added png_get_uint_31(png_ptr, buf) function.
+ Added PNG_UINT_32_MAX macro.
+ Renamed PNG_MAX_UINT to PNG_UINT_31_MAX.
+ Made png_zalloc() issue a png_warning and return NULL on potential
+ overflow.
+ Turn on PNG_NO_ZALLOC_ZERO by default in version 1.2.x
+ Revised "clobber list" in pnggccrd.c so it will compile under gcc-3.4.
+ Revised Borland portion of png_malloc() to return NULL or issue
+ png_error() according to setting of PNG_FLAG_MALLOC_NULL_MEM_OK.
+ Added PNG_NO_SEQUENTIAL_READ_SUPPORTED macro to conditionally remove
+ sequential read support.
+ Added some "#if PNG_WRITE_SUPPORTED" blocks.
+ Added #ifdef to remove some redundancy in png_malloc_default().
+ Use png_malloc instead of png_zalloc to allocate the pallete.
+
+Version 1.0.16rc1 and 1.2.6rc1 [August 4, 2004]
+ Fixed buffer overflow vulnerability (CVE-2004-0597) in png_handle_tRNS().
+ Fixed NULL dereference vulnerability (CVE-2004-0598) in png_handle_iCCP().
+ Fixed integer overflow vulnerability (CVE-2004-0599) in png_read_png().
+ Fixed some harmless bugs in png_handle_sBIT, etc, that would cause
+ duplicate chunk types to go undetected.
+ Fixed some timestamps in the -config version
+ Rearranged order of processing of color types in png_handle_tRNS().
+ Added ROWBYTES macro to calculate rowbytes without integer overflow.
+ Updated makefile.darwin and removed makefile.macosx from scripts directory.
+ Imposed default one million column, one-million row limits on the image
+ dimensions, and added png_set_user_limits() function to override them.
+ Revised use of PNG_SET_USER_LIMITS_SUPPORTED macro.
+ Fixed wrong cast of returns from png_get_user_width|height_max().
+ Changed some "keep the compiler happy" from empty statements to returns,
+ Revised libpng.txt to remove 1.2.x stuff from the 1.0.x distribution
+
+Version 1.0.16rc2 and 1.2.6rc2 [August 7, 2004]
+ Revised makefile.darwin and makefile.solaris. Removed makefile.macosx.
+ Revised pngtest's png_debug_malloc() to use png_malloc() instead of
+ png_malloc_default() which is not supposed to be exported.
+ Fixed off-by-one error in one of the conversions to PNG_ROWBYTES() in
+ pngpread.c. Bug was introduced in 1.2.6rc1.
+ Fixed bug in RGB to RGBX transformation introduced in 1.2.6rc1.
+ Fixed old bug in RGB to Gray transformation.
+ Fixed problem with 64-bit compilers by casting arguments to abs()
+ to png_int_32.
+ Changed "ln -sf" to "ln -f -s" in three makefiles (solaris, sco, so9).
+ Changed "HANDLE_CHUNK_*" to "PNG_HANDLE_CHUNK_*" (Cosmin)
+ Added "-@/bin/rm -f $(DL)/$(LIBNAME).so.$(PNGMAJ)" to 15 *NIX makefiles.
+ Added code to update the row_info->colortype in png_do_read_filler() (MSB).
+
+Version 1.0.16rc3 and 1.2.6rc3 [August 9, 2004]
+ Eliminated use of "abs()" in testing cHRM and gAMA values, to avoid
+ trouble with some 64-bit compilers. Created PNG_OUT_OF_RANGE() macro.
+ Revised documentation of png_set_keep_unknown_chunks().
+ Check handle_as_unknown status in pngpread.c, as in pngread.c previously.
+ Moved "PNG_HANDLE_CHUNK_*" macros out of PNG_INTERNAL section of png.h
+ Added "rim" definitions for CONST4 and CONST6 in pnggccrd.c
+
+Version 1.0.16rc4 and 1.2.6rc4 [August 10, 2004]
+ Fixed mistake in pngtest.c introduced in 1.2.6rc2 (declaration of
+ "pinfo" was out of place).
+
+Version 1.0.16rc5 and 1.2.6rc5 [August 10, 2004]
+ Moved "PNG_HANDLE_CHUNK_*" macros out of PNG_ASSEMBLER_CODE_SUPPORTED
+ section of png.h where they were inadvertently placed in version rc3.
+
+Version 1.2.6 and 1.0.16 [August 15, 2004]
+ Revised pngtest so memory allocation testing is only done when PNG_DEBUG==1.
+
+Version 1.2.7beta1 [August 26, 2004]
+ Removed unused pngasmrd.h file.
+ Removed references to uu.net for archived files. Added references to
+ PNG Spec (second edition) and the PNG ISO/IEC Standard.
+ Added "test-dd" target in 15 makefiles, to run pngtest in DESTDIR.
+ Fixed bug with "optimized window size" in the IDAT datastream, that
+ causes libpng to write PNG files with incorrect zlib header bytes.
+
+Version 1.2.7beta2 [August 28, 2004]
+ Fixed bug with sCAL chunk and big-endian machines (David Munro).
+ Undid new code added in 1.2.6rc2 to update the color_type in
+ png_set_filler().
+ Added png_set_add_alpha() that updates color type.
+
+Version 1.0.17rc1 and 1.2.7rc1 [September 4, 2004]
+ Revised png_set_strip_filler() to not remove alpha if color_type has alpha.
+
+Version 1.2.7 and 1.0.17 [September 12, 2004]
+ Added makefile.hp64
+ Changed projects/msvc/png32ms.def to scripts/png32ms.def in makefile.cygwin
+
+Version 1.2.8beta1 [November 1, 2004]
+ Fixed bug in png_text_compress() that would fail to complete a large block.
+ Fixed bug, introduced in libpng-1.2.7, that overruns a buffer during
+ strip alpha operation in png_do_strip_filler().
+ Added PNG_1_2_X definition in pngconf.h
+ Use #ifdef to comment out png_info_init in png.c and png_read_init in
+ pngread.c (as of 1.3.0)
+
+Version 1.2.8beta2 [November 2, 2004]
+ Reduce color_type to a nonalpha type after strip alpha operation in
+ png_do_strip_filler().
+
+Version 1.2.8beta3 [November 3, 2004]
+ Revised definitions of PNG_MAX_UINT_32, PNG_MAX_SIZE, and PNG_MAXSUM
+
+Version 1.2.8beta4 [November 12, 2004]
+ Fixed (again) definition of PNG_LIBPNG_VER_DLLNUM in png.h (Cosmin).
+ Added PNG_LIBPNG_BUILD_PRIVATE in png.h (Cosmin).
+ Set png_ptr->zstream.data_type to Z_BINARY, to avoid unnecessary detection
+ of data type in deflate (Cosmin).
+ Deprecated but continue to support SPECIALBUILD and PRIVATEBUILD in favor of
+ PNG_LIBPNG_BUILD_SPECIAL_STRING and PNG_LIBPNG_BUILD_PRIVATE_STRING.
+
+Version 1.2.8beta5 [November 20, 2004]
+ Use png_ptr->flags instead of png_ptr->transformations to pass
+ PNG_STRIP_ALPHA info to png_do_strip_filler(), to preserve ABI
+ compatibility.
+ Revised handling of SPECIALBUILD, PRIVATEBUILD,
+ PNG_LIBPNG_BUILD_SPECIAL_STRING and PNG_LIBPNG_BUILD_PRIVATE_STRING.
+
+Version 1.2.8rc1 [November 24, 2004]
+ Moved handling of BUILD macros from pngconf.h to png.h
+ Added definition of PNG_LIBPNG_BASE_TYPE in png.h, inadvertently
+ omitted from beta5.
+ Revised scripts/pngw32.rc
+ Despammed mailing addresses by masking "@" with "at".
+ Inadvertently installed a supposedly faster test version of pngrutil.c
+
+Version 1.2.8rc2 [November 26, 2004]
+ Added two missing "\" in png.h
+ Change tests in pngread.c and pngpread.c to
+ if (png_ptr->transformations || (png_ptr->flags&PNG_FLAG_STRIP_ALPHA))
+ png_do_read_transformations(png_ptr);
+
+Version 1.2.8rc3 [November 28, 2004]
+ Reverted pngrutil.c to version libpng-1.2.8beta5.
+ Added scripts/makefile.elf with supporting code in pngconf.h for symbol
+ versioning (John Bowler).
+
+Version 1.2.8rc4 [November 29, 2004]
+ Added projects/visualc7 (Simon-pierre).
+
+Version 1.2.8rc5 [November 29, 2004]
+ Fixed new typo in scripts/pngw32.rc
+
+Version 1.2.8 [December 3, 2004]
+ Removed projects/visualc7, added projects/visualc71.
+
+Version 1.2.9beta1 [February 21, 2006]
+ Initialized some structure members in pngwutil.c to avoid gcc-4.0.0 complaints
+ Revised man page and libpng.txt to make it clear that one should not call
+ png_read_end or png_write_end after png_read_png or png_write_png.
+ Updated references to png-mng-implement mailing list.
+ Fixed an incorrect typecast in pngrutil.c
+ Added PNG_NO_READ_SUPPORTED conditional for making a write-only library.
+ Added PNG_NO_WRITE_INTERLACING_SUPPORTED conditional.
+ Optimized alpha-inversion loops in pngwtran.c
+ Moved test for nonzero gamma outside of png_build_gamma_table() in pngrtran.c
+ Make sure num_trans is <= 256 before copying data in png_set_tRNS().
+ Make sure num_palette is <= 256 before copying data in png_set_PLTE().
+ Interchanged order of write_swap_alpha and write_invert_alpha transforms.
+ Added parentheses in the definition of PNG_LIBPNG_BUILD_TYPE (Cosmin).
+ Optimized zlib window flag (CINFO) in contrib/pngsuite/*.png (Cosmin).
+ Updated scripts/makefile.bc32 for Borland C++ 5.6 (Cosmin).
+ Exported png_get_uint_32, png_save_uint_32, png_get_uint_16, png_save_uint_16,
+ png_get_int_32, png_save_int_32, png_get_uint_31 (Cosmin).
+ Added type cast (png_byte) in png_write_sCAL() (Cosmin).
+ Fixed scripts/makefile.cygwin (Christian Biesinger, Cosmin).
+ Default iTXt support was inadvertently enabled.
+
+Version 1.2.9beta2 [February 21, 2006]
+ Check for png_rgb_to_gray and png_gray_to_rgb read transformations before
+ checking for png_read_dither in pngrtran.c
+ Revised checking of chromaticity limits to accommodate extended RGB
+ colorspace (John Denker).
+ Changed line endings in some of the project files to CRLF, even in the
+ "Unix" tar distributions (Cosmin).
+ Made png_get_int_32 and png_save_int_32 always available (Cosmin).
+ Updated scripts/pngos2.def, scripts/pngw32.def and projects/wince/png32ce.def
+ with the newly exported functions.
+ Eliminated distributions without the "configure" script.
+ Updated INSTALL instructions.
+
+Version 1.2.9beta3 [February 24, 2006]
+ Fixed CRCRLF line endings in contrib/visupng/VisualPng.dsp
+ Made libpng.pc respect EXEC_PREFIX (D. P. Kreil, J. Bowler)
+ Removed reference to pngasmrd.h from Makefile.am
+ Renamed CHANGES to ChangeLog.
+ Renamed LICENSE to COPYING.
+ Renamed ANNOUNCE to NEWS.
+ Created AUTHORS file.
+
+Version 1.2.9beta4 [March 3, 2006]
+ Changed definition of PKGCONFIG from $prefix/lib to $libdir in configure.ac
+ Reverted to filenames LICENSE and ANNOUNCE; removed AUTHORS and COPYING.
+ Removed newline from the end of some error and warning messages.
+ Removed test for sqrt() from configure.ac and configure.
+ Made swap tables in pngtrans.c PNG_CONST (Carlo Bramix).
+ Disabled default iTXt support that was inadvertently enabled in
+ libpng-1.2.9beta1.
+ Added "OS2" to list of systems that don't need underscores, in pnggccrd.c
+ Removed libpng version and date from *.c files.
+
+Version 1.2.9beta5 [March 4, 2006]
+ Removed trailing blanks from source files.
+ Put version and date of latest change in each source file, and changed
+ copyright year accordingly.
+ More cleanup of configure.ac, Makefile.am, and associated scripts.
+ Restored scripts/makefile.elf which was inadvertently deleted.
+
+Version 1.2.9beta6 [March 6, 2006]
+ Fixed typo (RELEASE) in configuration files.
+
+Version 1.2.9beta7 [March 7, 2006]
+ Removed libpng.vers and libpng.sym from libpng12_la_SOURCES in Makefile.am
+ Fixed inconsistent #ifdef's around png_sig_bytes() and png_set_sCAL_s()
+ in png.h.
+ Updated makefile.elf as suggested by debian.
+ Made cosmetic changes to some makefiles, adding LN_SF and other macros.
+ Made some makefiles accept "exec_prefix".
+
+Version 1.2.9beta8 [March 9, 2006]
+ Fixed some "#if defined (..." which should be "#if defined(..."
+ Bug introduced in libpng-1.2.8.
+ Fixed inconsistency in definition of png_default_read_data()
+ Restored blank that was lost from makefile.sggcc "clean" target in beta7.
+ Revised calculation of "current" and "major" for irix in ltmain.sh
+ Changed "mkdir" to "MKDIR_P" in some makefiles.
+ Separated PNG_EXPAND and PNG_EXPAND_tRNS.
+ Added png_set_expand_gray_1_2_4_to_8() and deprecated
+ png_set_gray_1_2_4_to_8() which also expands tRNS to alpha.
+
+Version 1.2.9beta9 [March 10, 2006]
+ Include "config.h" in pngconf.h when available.
+ Added some checks for NULL png_ptr or NULL info_ptr (timeless)
+
+Version 1.2.9beta10 [March 20, 2006]
+ Removed extra CR from contrib/visualpng/VisualPng.dsw (Cosmin)
+ Made pnggccrd.c PIC-compliant (Christian Aichinger).
+ Added makefile.mingw (Wolfgang Glas).
+ Revised pngconf.h MMX checking.
+
+Version 1.2.9beta11 [March 22, 2006]
+ Fixed out-of-order declaration in pngwrite.c that was introduced in beta9
+ Simplified some makefiles by using LIBSO, LIBSOMAJ, and LIBSOVER macros.
+
+Version 1.2.9rc1 [March 31, 2006]
+ Defined PNG_USER_PRIVATEBUILD when including "pngusr.h" (Cosmin).
+ Removed nonsensical assertion check from pngtest.c (Cosmin).
+
+Version 1.2.9 [April 14, 2006]
+ Revised makefile.beos and added "none" selector in ltmain.sh
+
+Version 1.2.10beta1 [April 15, 2006]
+ Renamed "config.h" to "png_conf.h" and revised Makefile.am to add
+ -DPNG_BUILDING_LIBPNG to compile directive, and modified pngconf.h
+ to include png_conf.h only when PNG_BUILDING_LIBPNG is defined.
+
+Version 1.2.10beta2 [April 15, 2006]
+ Manually updated Makefile.in and configure. Changed png_conf.h.in
+ back to config.h.
+
+Version 1.2.10beta3 [April 15, 2006]
+ Change png_conf.h back to config.h in pngconf.h.
+
+Version 1.2.10beta4 [April 16, 2006]
+ Change PNG_BUILDING_LIBPNG to PNG_CONFIGURE_LIBPNG in config/Makefile*.
+
+Version 1.2.10beta5 [April 16, 2006]
+ Added a configure check for compiling assembler code in pnggccrd.c
+
+Version 1.2.10beta6 [April 17, 2006]
+ Revised the configure check for pnggccrd.c
+ Moved -DPNG_CONFIGURE_LIBPNG into @LIBPNG_DEFINES@
+ Added @LIBPNG_DEFINES@ to arguments when building libpng.sym
+
+Version 1.2.10beta7 [April 18, 2006]
+ Change "exec_prefix=$prefix" to "exec_prefix=$(prefix)" in makefiles.
+
+Version 1.2.10rc1 [April 19, 2006]
+ Ensure pngconf.h doesn't define both PNG_USE_PNGGCCRD and PNG_USE_PNGVCRD
+ Fixed "LN_FS" typo in makefile.sco and makefile.solaris.
+
+Version 1.2.10rc2 [April 20, 2006]
+ Added a backslash between -DPNG_CONFIGURE_LIBPNG and -DPNG_NO_ASSEMBLER_CODE
+ in configure.ac and configure
+ Made the configure warning about versioned symbols less arrogant.
+
+Version 1.2.10rc3 [April 21, 2006]
+ Added a note in libpng.txt that png_set_sig_bytes(8) can be used when
+ writing an embedded PNG without the 8-byte signature.
+ Revised makefiles and configure to avoid making links to libpng.so.*
+
+Version 1.2.10 [April 23, 2006]
+ Reverted configure to "rc2" state.
+
+Version 1.2.11beta1 [May 31, 2006]
+ scripts/libpng.pc.in contained "configure" style version info and would
+ not work with makefiles.
+ The shared-library makefiles were linking to libpng.so.0 instead of
+ libpng.so.3 compatibility as the library.
+
+Version 1.2.11beta2 [June 2, 2006]
+ Increased sprintf buffer from 50 to 52 chars in pngrutil.c to avoid
+ buffer overflow.
+ Fixed bug in example.c (png_set_palette_rgb -> png_set_palette_to_rgb)
+
+Version 1.2.11beta3 [June 5, 2006]
+ Prepended "#! /bin/sh" to ltmail.sh and contrib/pngminus/*.sh (Cosmin).
+ Removed the accidental leftover Makefile.in~ (Cosmin).
+ Avoided potential buffer overflow and optimized buffer in
+ png_write_sCAL(), png_write_sCAL_s() (Cosmin).
+ Removed the include directories and libraries from CFLAGS and LDFLAGS
+ in scripts/makefile.gcc (Nelson A. de Oliveira, Cosmin).
+
+Version 1.2.11beta4 [June 6, 2006]
+ Allow zero-length IDAT chunks after the entire zlib datastream, but not
+ after another intervening chunk type.
+
+Version 1.0.19rc1, 1.2.11rc1 [June 13, 2006]
+ Deleted extraneous square brackets from [config.h] in configure.ac
+
+Version 1.0.19rc2, 1.2.11rc2 [June 14, 2006]
+ Added prototypes for PNG_INCH_CONVERSIONS functions to png.h
+ Revised INSTALL and autogen.sh
+ Fixed typo in several makefiles (-W1 should be -Wl)
+ Added typedef for png_int_32 and png_uint_32 on 64-bit systems.
+
+Version 1.0.19rc3, 1.2.11rc3 [June 15, 2006]
+ Removed the new typedefs for 64-bit systems (delay until version 1.4.0)
+ Added one zero element to png_gamma_shift[] array in pngrtran.c to avoid
+ reading out of bounds.
+
+Version 1.0.19rc4, 1.2.11rc4 [June 15, 2006]
+ Really removed the new typedefs for 64-bit systems.
+
+Version 1.0.19rc5, 1.2.11rc5 [June 22, 2006]
+ Removed png_sig_bytes entry from scripts/pngw32.def
+
+Version 1.0.19, 1.2.11 [June 26, 2006]
+ None.
+
+Version 1.0.20, 1.2.12 [June 27, 2006]
+ Really increased sprintf buffer from 50 to 52 chars in pngrutil.c to avoid
+ buffer overflow.
+
+Version 1.2.13beta1 [October 2, 2006]
+ Removed AC_FUNC_MALLOC from configure.ac
+ Work around Intel-Mac compiler bug by setting PNG_NO_MMX_CODE in pngconf.h
+ Change "logical" to "bitwise" throughout documentation.
+ Detect and fix attempt to write wrong iCCP profile length (CVE-2006-7244)
+
+Version 1.0.21, 1.2.13 [November 14, 2006]
+ Fix potential buffer overflow in sPLT chunk handler.
+ Fix Makefile.am to not try to link to noexistent files.
+ Check all exported functions for NULL png_ptr.
+
+Version 1.2.14beta1 [November 17, 2006]
+ Relocated three misplaced tests for NULL png_ptr.
+ Built Makefile.in with automake-1.9.6 instead of 1.9.2.
+ Build configure with autoconf-2.60 instead of 2.59
+
+Version 1.2.14beta2 [November 17, 2006]
+ Added some typecasts in png_zalloc().
+
+Version 1.2.14rc1 [November 20, 2006]
+ Changed "strtod" to "png_strtod" in pngrutil.c
+
+Version 1.0.22, 1.2.14 [November 27, 2006]
+ Added missing "$(srcdir)" in Makefile.am and Makefile.in
+
+Version 1.2.15beta1 [December 3, 2006]
+ Generated configure with autoconf-2.61 instead of 2.60
+ Revised configure.ac to update libpng.pc and libpng-config.
+
+Version 1.2.15beta2 [December 3, 2006]
+ Always export MMX asm functions, just stubs if not building pnggccrd.c
+
+Version 1.2.15beta3 [December 4, 2006]
+ Add "png_bytep" typecast to profile while calculating length in pngwutil.c
+
+Version 1.2.15beta4 [December 7, 2006]
+ Added scripts/CMakeLists.txt
+ Changed PNG_NO_ASSEMBLER_CODE to PNG_NO_MMX_CODE in scripts, like 1.4.0beta
+
+Version 1.2.15beta5 [December 7, 2006]
+ Changed some instances of PNG_ASSEMBLER_* to PNG_MMX_* in pnggccrd.c
+ Revised scripts/CMakeLists.txt
+
+Version 1.2.15beta6 [December 13, 2006]
+ Revised scripts/CMakeLists.txt and configure.ac
+
+Version 1.2.15rc1 [December 18, 2006]
+ Revised scripts/CMakeLists.txt
+
+Version 1.2.15rc2 [December 21, 2006]
+ Added conditional #undef jmpbuf in pngtest.c to undo #define in AIX headers.
+ Added scripts/makefile.nommx
+
+Version 1.2.15rc3 [December 25, 2006]
+ Fixed shared library numbering error that was introduced in 1.2.15beta6.
+
+Version 1.2.15rc4 [December 27, 2006]
+ Fixed handling of rgb_to_gray when png_ptr->color.gray isn't set.
+
+Version 1.2.15rc5 [December 31, 2006]
+ Revised handling of rgb_to_gray.
+
+Version 1.2.15 [January 5, 2007]
+ Added some (unsigned long) typecasts in pngtest.c to avoid printing errors.
+
+Version 1.2.16beta1 [January 6, 2007]
+ Fix bugs in makefile.nommx
+
+Version 1.2.16beta2 [January 16, 2007]
+ Revised scripts/CMakeLists.txt
+
+Version 1.2.16 [January 31, 2007]
+ No changes.
+
+Version 1.2.17beta1 [March 6, 2007]
+ Revised scripts/CMakeLists.txt to install both shared and static libraries.
+ Deleted a redundant line from pngset.c.
+
+Version 1.2.17beta2 [April 26, 2007]
+ Relocated misplaced test for png_ptr == NULL in pngpread.c
+ Change "==" to "&" for testing PNG_RGB_TO_GRAY_ERR & PNG_RGB_TO_GRAY_WARN
+ flags.
+ Changed remaining instances of PNG_ASSEMBLER_* to PNG_MMX_*
+ Added pngerror() when write_IHDR fails in deflateInit2().
+ Added "const" to some array declarations.
+ Mention examples of libpng usage in the libpng*.txt and libpng.3 documents.
+
+Version 1.2.17rc1 [May 4, 2007]
+ No changes.
+
+Version 1.2.17rc2 [May 8, 2007]
+ Moved several PNG_HAVE_* macros out of PNG_INTERNAL because applications
+ calling set_unknown_chunk_location() need them.
+ Changed transformation flag from PNG_EXPAND_tRNS to PNG_EXPAND in
+ png_set_expand_gray_1_2_4_to_8().
+ Added png_ptr->unknown_chunk to hold working unknown chunk data, so it
+ can be free'ed in case of error. Revised unknown chunk handling in
+ pngrutil.c and pngpread.c to use this structure.
+
+Version 1.2.17rc3 [May 8, 2007]
+ Revised symbol-handling in configure script.
+
+Version 1.2.17rc4 [May 10, 2007]
+ Revised unknown chunk handling to avoid storing unknown critical chunks.
+
+Version 1.0.25 [May 15, 2007]
+Version 1.2.17 [May 15, 2007]
+ Added "png_ptr->num_trans=0" before error return in png_handle_tRNS,
+ to eliminate a vulnerability (CVE-2007-2445, CERT VU#684664)
+
+Version 1.0.26 [May 15, 2007]
+Version 1.2.18 [May 15, 2007]
+ Reverted the libpng-1.2.17rc3 change to symbol-handling in configure script
+
+Version 1.2.19beta1 [May 18, 2007]
+ Changed "const static" to "static PNG_CONST" everywhere, mostly undoing
+ change of libpng-1.2.17beta2. Changed other "const" to "PNG_CONST"
+ Changed some handling of unused parameters, to avoid compiler warnings.
+ "if (unused == NULL) return;" becomes "unused = unused".
+
+Version 1.2.19beta2 [May 18, 2007]
+ Only use the valid bits of tRNS value in png_do_expand() (Brian Cartier)
+
+Version 1.2.19beta3 [May 19, 2007]
+ Add some "png_byte" typecasts in png_check_keyword() and write new_key
+ instead of key in zTXt chunk (Kevin Ryde).
+
+Version 1.2.19beta4 [May 21, 2007]
+ Add png_snprintf() function and use it in place of sprint() for improved
+ defense against buffer overflows.
+
+Version 1.2.19beta5 [May 21, 2007]
+ Fixed png_handle_tRNS() to only use the valid bits of tRNS value.
+ Changed handling of more unused parameters, to avoid compiler warnings.
+ Removed some PNG_CONST in pngwutil.c to avoid compiler warnings.
+
+Version 1.2.19beta6 [May 22, 2007]
+ Added some #ifdef PNG_MMX_CODE_SUPPORTED where needed in pngvcrd.c
+ Added a special "_MSC_VER" case that defines png_snprintf to _snprintf
+
+Version 1.2.19beta7 [May 22, 2007]
+ Squelched png_squelch_warnings() in pnggccrd.c and added
+ an #ifdef PNG_MMX_CODE_SUPPORTED block around the declarations that caused
+ the warnings that png_squelch_warnings was squelching.
+
+Version 1.2.19beta8 [May 22, 2007]
+ Removed __MMX__ from test in pngconf.h.
+
+Version 1.2.19beta9 [May 23, 2007]
+ Made png_squelch_warnings() available via PNG_SQUELCH_WARNINGS macro.
+ Revised png_squelch_warnings() so it might work.
+ Updated makefile.sgcc and makefile.solaris; added makefile.solaris-x86.
+
+Version 1.2.19beta10 [May 24, 2007]
+ Resquelched png_squelch_warnings(), use "__attribute__((used))" instead.
+
+Version 1.4.0beta1 [April 20, 2006]
+ Enabled iTXt support (changes png_struct, thus requires so-number change).
+ Cleaned up PNG_ASSEMBLER_CODE_SUPPORTED vs PNG_MMX_CODE_SUPPORTED
+ Eliminated PNG_1_0_X and PNG_1_2_X macros.
+ Removed deprecated functions png_read_init, png_write_init, png_info_init,
+ png_permit_empty_plte, png_set_gray_1_2_4_to_8, png_check_sig, and
+ removed the deprecated macro PNG_MAX_UINT.
+ Moved "PNG_INTERNAL" parts of png.h and pngconf.h into pngintrn.h
+ Removed many WIN32_WCE #ifdefs (Cosmin).
+ Reduced dependency on C-runtime library when on Windows (Simon-Pierre)
+ Replaced sprintf() with png_sprintf() (Simon-Pierre)
+
+Version 1.4.0beta2 [April 20, 2006]
+ Revised makefiles and configure to avoid making links to libpng.so.*
+ Moved some leftover MMX-related defines from pngconf.h to pngintrn.h
+ Updated scripts/pngos2.def, pngw32.def, and projects/wince/png32ce.def
+
+Version 1.4.0beta3 [May 10, 2006]
+ Updated scripts/pngw32.def to comment out MMX functions.
+ Added PNG_NO_GET_INT_32 and PNG_NO_SAVE_INT_32 macros.
+ Scripts/libpng.pc.in contained "configure" style version info and would
+ not work with makefiles.
+ Revised pngconf.h and added pngconf.h.in, so makefiles and configure can
+ pass defines to libpng and applications.
+
+Version 1.4.0beta4 [May 11, 2006]
+ Revised configure.ac, Makefile.am, and many of the makefiles to write
+ their defines in pngconf.h.
+
+Version 1.4.0beta5 [May 15, 2006]
+ Added a missing semicolon in Makefile.am and Makefile.in
+ Deleted extraneous square brackets from configure.ac
+
+Version 1.4.0beta6 [June 2, 2006]
+ Increased sprintf buffer from 50 to 52 chars in pngrutil.c to avoid
+ buffer overflow.
+ Changed sonum from 0 to 1.
+ Removed unused prototype for png_check_sig() from png.h
+
+Version 1.4.0beta7 [June 16, 2006]
+ Exported png_write_sig (Cosmin).
+ Optimized buffer in png_handle_cHRM() (Cosmin).
+ Set pHYs = 2835 x 2835 pixels per meter, and added
+ sCAL = 0.352778e-3 x 0.352778e-3 meters, in pngtest.png (Cosmin).
+ Added png_set_benign_errors(), png_benign_error(), png_chunk_benign_error().
+ Added typedef for png_int_32 and png_uint_32 on 64-bit systems.
+ Added "(unsigned long)" typecast on png_uint_32 variables in printf lists.
+
+Version 1.4.0beta8 [June 22, 2006]
+ Added demonstration of user chunk support in pngtest.c, to support the
+ public sTER chunk and a private vpAg chunk.
+
+Version 1.4.0beta9 [July 3, 2006]
+ Removed ordinals from scripts/pngw32.def and removed png_info_int and
+ png_set_gray_1_2_4_to_8 entries.
+ Inline call of png_get_uint_32() in png_get_uint_31().
+ Use png_get_uint_31() to get vpAg width and height in pngtest.c
+ Removed WINCE and Netware projects.
+ Removed standalone Y2KINFO file.
+
+Version 1.4.0beta10 [July 12, 2006]
+ Eliminated automatic copy of pngconf.h to pngconf.h.in from configure and
+ some makefiles, because it was not working reliably. Instead, distribute
+ pngconf.h.in along with pngconf.h and cause configure and some of the
+ makefiles to update pngconf.h from pngconf.h.in.
+ Added pngconf.h to DEPENDENCIES in Makefile.am
+
+Version 1.4.0beta11 [August 19, 2006]
+ Removed AC_FUNC_MALLOC from configure.ac.
+ Added a warning when writing iCCP profile with mismatched profile length.
+ Patched pnggccrd.c to assemble on x86_64 platforms.
+ Moved chunk header reading into a separate function png_read_chunk_header()
+ in pngrutil.c. The chunk header (len+sig) is now serialized in a single
+ operation (Cosmin).
+ Implemented support for I/O states. Added png_ptr member io_state, and
+ functions png_get_io_chunk_name() and png_get_io_state() in pngget.c
+ (Cosmin).
+ Added png_get_io_chunk_name and png_get_io_state to scripts/*.def (Cosmin).
+ Renamed scripts/pngw32.* to scripts/pngwin.* (Cosmin).
+ Removed the include directories and libraries from CFLAGS and LDFLAGS
+ in scripts/makefile.gcc (Cosmin).
+ Used png_save_uint_32() to set vpAg width and height in pngtest.c (Cosmin).
+ Cast to proper type when getting/setting vpAg units in pngtest.c (Cosmin).
+ Added pngintrn.h to the Visual C++ projects (Cosmin).
+ Removed scripts/list (Cosmin).
+ Updated copyright year in scripts/pngwin.def (Cosmin).
+ Removed PNG_TYPECAST_NULL and used standard NULL consistently (Cosmin).
+ Disallowed the user to redefine png_size_t, and enforced a consistent use
+ of png_size_t across libpng (Cosmin).
+ Changed the type of png_ptr->rowbytes, PNG_ROWBYTES() and friends
+ to png_size_t (Cosmin).
+ Removed png_convert_size() and replaced png_sizeof with sizeof (Cosmin).
+ Removed some unnecessary type casts (Cosmin).
+ Changed prototype of png_get_compression_buffer_size() and
+ png_set_compression_buffer_size() to work with png_size_t instead of
+ png_uint_32 (Cosmin).
+ Removed png_memcpy_check() and png_memset_check() (Cosmin).
+ Fixed a typo (png_byte --> png_bytep) in libpng.3 and libpng.txt (Cosmin).
+ Clarified that png_zalloc() does not clear the allocated memory,
+ and png_zalloc() and png_zfree() cannot be PNGAPI (Cosmin).
+ Renamed png_mem_size_t to png_alloc_size_t, fixed its definition in
+ pngconf.h, and used it in all memory allocation functions (Cosmin).
+ Renamed pngintrn.h to pngpriv.h, added a comment at the top of the file
+ mentioning that the symbols declared in that file are private, and
+ updated the scripts and the Visual C++ projects accordingly (Cosmin).
+ Removed circular references between pngconf.h and pngconf.h.in in
+ scripts/makefile.vc*win32 (Cosmin).
+ Removing trailing '.' from the warning and error messages (Cosmin).
+ Added pngdefs.h that is built by makefile or configure, instead of
+ pngconf.h.in (Glenn).
+ Detect and fix attempt to write wrong iCCP profile length.
+
+Version 1.4.0beta12 [October 19, 2006]
+ Changed "logical" to "bitwise" in the documentation.
+ Work around Intel-Mac compiler bug by setting PNG_NO_MMX_CODE in pngconf.h
+ Add a typecast to stifle compiler warning in pngrutil.c
+
+Version 1.4.0beta13 [November 10, 2006]
+ Fix potential buffer overflow in sPLT chunk handler.
+ Fix Makefile.am to not try to link to noexistent files.
+
+Version 1.4.0beta14 [November 15, 2006]
+ Check all exported functions for NULL png_ptr.
+
+Version 1.4.0beta15 [November 17, 2006]
+ Relocated two misplaced tests for NULL png_ptr.
+ Built Makefile.in with automake-1.9.6 instead of 1.9.2.
+ Build configure with autoconf-2.60 instead of 2.59
+ Add "install: all" in Makefile.am so "configure; make install" will work.
+
+Version 1.4.0beta16 [November 17, 2006]
+ Added a typecast in png_zalloc().
+
+Version 1.4.0beta17 [December 4, 2006]
+ Changed "new_key[79] = '\0';" to "(*new_key)[79] = '\0';" in pngwutil.c
+ Add "png_bytep" typecast to profile while calculating length in pngwutil.c
+
+Version 1.4.0beta18 [December 7, 2006]
+ Added scripts/CMakeLists.txt
+
+Version 1.4.0beta19 [May 16, 2007]
+ Revised scripts/CMakeLists.txt
+ Rebuilt configure and Makefile.in with newer tools.
+ Added conditional #undef jmpbuf in pngtest.c to undo #define in AIX headers.
+ Added scripts/makefile.nommx
+
+Version 1.4.0beta20 [July 9, 2008]
+ Moved several PNG_HAVE_* macros from pngpriv.h to png.h because applications
+ calling set_unknown_chunk_location() need them.
+ Moved several macro definitions from pngpriv.h to pngconf.h
+ Merge with changes to the 1.2.X branch, as of 1.2.30beta04.
+ Deleted all use of the MMX assembler code and Intel-licensed optimizations.
+ Revised makefile.mingw
+
+Version 1.4.0beta21 [July 21, 2008]
+ Moved local array "chunkdata" from pngrutil.c to the png_struct, so
+ it will be freed by png_read_destroy() in case of a read error (Kurt
+ Christensen).
+
+Version 1.4.0beta22 [July 21, 2008]
+ Change "purpose" and "buffer" to png_ptr->chunkdata to avoid memory leaking.
+
+Version 1.4.0beta23 [July 22, 2008]
+ Change "chunkdata = NULL" to "png_ptr->chunkdata = NULL" several places in
+ png_decompress_chunk().
+
+Version 1.4.0beta24 [July 25, 2008]
+ Change all remaining "chunkdata" to "png_ptr->chunkdata" in
+ png_decompress_chunk(), and remove "chunkdata" from parameter list.
+ Put a call to png_check_chunk_name() in png_read_chunk_header().
+ Revised png_check_chunk_name() to reject a name with a lowercase 3rd byte.
+ Removed two calls to png_check_chunk_name() occurring later in the process.
+ Define PNG_NO_ERROR_NUMBERS by default in pngconf.h
+
+Version 1.4.0beta25 [July 30, 2008]
+ Added a call to png_check_chunk_name() in pngpread.c
+ Reverted png_check_chunk_name() to accept a name with a lowercase 3rd byte.
+ Added png_push_have_buffer() function to pngpread.c
+ Eliminated PNG_BIG_ENDIAN_SUPPORTED and associated png_get_* macros.
+ Made inline expansion of png_get_*() optional with PNG_USE_READ_MACROS.
+ Eliminated all PNG_USELESS_TESTS and PNG_CORRECT_PALETTE_SUPPORTED code.
+ Synced contrib directory and configure files with libpng-1.2.30beta06.
+ Eliminated no-longer-used pngdefs.h (but it's still built in the makefiles)
+ Relocated a misplaced "#endif /* PNG_NO_WRITE_FILTER */" in pngwutil.c
+
+Version 1.4.0beta26 [August 4, 2008]
+ Removed png_push_have_buffer() function in pngpread.c. It increased the
+ compiled library size slightly.
+ Changed "-Wall" to "-W -Wall" in the CFLAGS in all makefiles (Cosmin Truta)
+ Declared png_ptr "volatile" in pngread.c and pngwrite.c to avoid warnings.
+ Updated contrib/visupng/cexcept.h to version 2.0.1
+ Added PNG_LITERAL_CHARACTER macros for #, [, and ].
+
+Version 1.4.0beta27 [August 5, 2008]
+ Revised usage of PNG_LITERAL_SHARP in pngerror.c.
+ Moved newline character from individual png_debug messages into the
+ png_debug macros.
+ Allow user to #define their own png_debug, png_debug1, and png_debug2.
+
+Version 1.4.0beta28 [August 5, 2008]
+ Revised usage of PNG_LITERAL_SHARP in pngerror.c.
+ Added PNG_STRING_NEWLINE macro
+
+Version 1.4.0beta29 [August 9, 2008]
+ Revised usage of PNG_STRING_NEWLINE to work on non-ISO compilers.
+ Added PNG_STRING_COPYRIGHT macro.
+ Added non-ISO versions of png_debug macros.
+
+Version 1.4.0beta30 [August 14, 2008]
+ Added premultiplied alpha feature (Volker Wiendl).
+
+Version 1.4.0beta31 [August 18, 2008]
+ Moved png_set_premultiply_alpha from pngtrans.c to pngrtran.c
+ Removed extra crc check at the end of png_handle_cHRM(). Bug introduced
+ in libpng-1.4.0beta20.
+
+Version 1.4.0beta32 [August 19, 2008]
+ Added PNG_WRITE_FLUSH_SUPPORTED block around new png_flush() call.
+ Revised PNG_NO_STDIO version of png_write_flush()
+
+Version 1.4.0beta33 [August 20, 2008]
+ Added png_get|set_chunk_cache_max() to limit the total number of sPLT,
+ text, and unknown chunks that can be stored.
+
+Version 1.4.0beta34 [September 6, 2008]
+ Shortened tIME_string to 29 bytes in pngtest.c
+ Fixed off-by-one error introduced in png_push_read_zTXt() function in
+ libpng-1.2.30beta04/pngpread.c (Harald van Dijk)
+
+Version 1.4.0beta35 [October 6, 2008]
+ Changed "trans_values" to "trans_color".
+ Changed so-number from 0 to 14. Some OS do not like 0.
+ Revised makefile.darwin to fix shared library numbering.
+ Change png_set_gray_1_2_4_to_8() to png_set_expand_gray_1_2_4_to_8()
+ in example.c (debian bug report)
+
+Version 1.4.0beta36 [October 25, 2008]
+ Sync with tEXt vulnerability fix in libpng-1.2.33rc02.
+
+Version 1.4.0beta37 [November 13, 2008]
+ Added png_check_cHRM in png.c and moved checking from pngget.c, pngrutil.c,
+ and pngwrite.c
+
+Version 1.4.0beta38 [November 22, 2008]
+ Added check for zero-area RGB cHRM triangle in png_check_cHRM() and
+ png_check_cHRM_fixed().
+
+Version 1.4.0beta39 [November 23, 2008]
+ Revised png_warning() to write its message on standard output by default
+ when warning_fn is NULL.
+
+Version 1.4.0beta40 [November 24, 2008]
+ Eliminated png_check_cHRM(). Instead, always use png_check_cHRM_fixed().
+ In png_check_cHRM_fixed(), ensure white_y is > 0, and removed redundant
+ check for all-zero coordinates that is detected by the triangle check.
+
+Version 1.4.0beta41 [November 26, 2008]
+ Fixed string vs pointer-to-string error in png_check_keyword().
+ Rearranged test expressions in png_check_cHRM_fixed() to avoid internal
+ overflows.
+ Added PNG_NO_CHECK_cHRM conditional.
+
+Version 1.4.0beta42, 43 [December 1, 2008]
+ Merge png_debug with version 1.2.34beta04.
+
+Version 1.4.0beta44 [December 6, 2008]
+ Removed redundant check for key==NULL before calling png_check_keyword()
+ to ensure that new_key gets initialized and removed extra warning
+ (Merge with version 1.2.34beta05 -- Arvan Pritchard).
+
+Version 1.4.0beta45 [December 9, 2008]
+ In png_write_png(), respect the placement of the filler bytes in an earlier
+ call to png_set_filler() (Jim Barry).
+
+Version 1.4.0beta46 [December 10, 2008]
+ Undid previous change and added PNG_TRANSFORM_STRIP_FILLER_BEFORE and
+ PNG_TRANSFORM_STRIP_FILLER_AFTER conditionals and deprecated
+ PNG_TRANSFORM_STRIP_FILLER (Jim Barry).
+
+Version 1.4.0beta47 [December 15, 2008]
+ Support for dithering was disabled by default, because it has never
+ been well tested and doesn't work very well. The code has not
+ been removed, however, and can be enabled by building libpng with
+ PNG_READ_DITHER_SUPPORTED defined.
+
+Version 1.4.0beta48 [February 14, 2009]
+ Added new exported function png_calloc().
+ Combined several instances of png_malloc(); png_memset() into png_calloc().
+ Removed prototype for png_freeptr() that was added in libpng-1.4.0beta24
+ but was never defined.
+
+Version 1.4.0beta49 [February 28, 2009]
+ Added png_fileno() macro to pngconf.h, used in pngwio.c
+ Corrected order of #ifdef's in png_debug definition in png.h
+ Fixed bug introduced in libpng-1.4.0beta48 with the memset arguments
+ for pcal_params.
+ Fixed order of #ifdef directives in the png_debug defines in png.h
+ (bug introduced in libpng-1.2.34/1.4.0beta29).
+ Revised comments in png_set_read_fn() and png_set_write_fn().
+
+Version 1.4.0beta50 [March 18, 2009]
+ Use png_calloc() instead of png_malloc() to allocate big_row_buf when
+ reading an interlaced file, to avoid a possible UMR.
+ Undid revision of PNG_NO_STDIO version of png_write_flush(). Users
+ having trouble with fflush() can build with PNG_NO_WRITE_FLUSH defined
+ or supply their own flush_fn() replacement.
+ Revised libpng*.txt and png.h documentation about use of png_write_flush()
+ and png_set_write_fn().
+ Removed fflush() from pngtest.c.
+ Added "#define PNG_NO_WRITE_FLUSH" to contrib/pngminim/encoder/pngusr.h
+
+Version 1.4.0beta51 [March 21, 2009]
+ Removed new png_fileno() macro from pngconf.h .
+
+Version 1.4.0beta52 [March 27, 2009]
+ Relocated png_do_chop() ahead of building gamma tables in pngrtran.c
+ This avoids building 16-bit gamma tables unnecessarily.
+ Removed fflush() from pngtest.c.
+ Added "#define PNG_NO_WRITE_FLUSH" to contrib/pngminim/encoder/pngusr.h
+ Added a section on differences between 1.0.x and 1.2.x to libpng.3/libpng.txt
+
+Version 1.4.0beta53 [April 1, 2009]
+ Removed some remaining MMX macros from pngpriv.h
+ Fixed potential memory leak of "new_name" in png_write_iCCP() (Ralph Giles)
+
+Version 1.4.0beta54 [April 13, 2009]
+ Added "ifndef PNG_SKIP_SETJMP_CHECK" block in pngconf.h to allow
+ application code writers to bypass the check for multiple inclusion
+ of setjmp.h when they know that it is safe to ignore the situation.
+ Eliminated internal use of setjmp() in pngread.c and pngwrite.c
+ Reordered ancillary chunks in pngtest.png to be the same as what
+ pngtest now produces, and made some cosmetic changes to pngtest output.
+ Eliminated deprecated png_read_init_3() and png_write_init_3() functions.
+
+Version 1.4.0beta55 [April 15, 2009]
+ Simplified error handling in pngread.c and pngwrite.c by putting
+ the new png_read_cleanup() and png_write_cleanup() functions inline.
+
+Version 1.4.0beta56 [April 25, 2009]
+ Renamed "user_chunk_data" to "my_user_chunk_data" in pngtest.c to suppress
+ "shadowed declaration" warning from gcc-4.3.3.
+ Renamed "gamma" to "png_gamma" in pngset.c to avoid "shadowed declaration"
+ warning about a global "gamma" variable in math.h on some platforms.
+
+Version 1.4.0beta57 [May 2, 2009]
+ Removed prototype for png_freeptr() that was added in libpng-1.4.0beta24
+ but was never defined (again).
+ Rebuilt configure scripts with autoconf-2.63 instead of 2.62
+ Removed pngprefs.h and MMX from makefiles
+
+Version 1.4.0beta58 [May 14, 2009]
+ Changed pngw32.def to pngwin.def in makefile.mingw (typo was introduced
+ in beta57).
+ Clarified usage of sig_bit versus sig_bit_p in example.c (Vincent Torri)
+
+Version 1.4.0beta59 [May 15, 2009]
+ Reformated sources in libpng style (3-space intentation, comment format)
+ Fixed typo in libpng docs (PNG_FILTER_AVE should be PNG_FILTER_AVG)
+ Added sections about the git repository and our coding style to the
+ documentation
+ Relocated misplaced #endif in pngwrite.c, sCAL chunk handler.
+
+Version 1.4.0beta60 [May 19, 2009]
+ Conditionally compile png_read_finish_row() which is not used by
+ progressive readers.
+ Added contrib/pngminim/preader to demonstrate building minimal progressive
+ decoder, based on contrib/gregbook with embedded libpng and zlib.
+
+Version 1.4.0beta61 [May 20, 2009]
+ In contrib/pngminim/*, renamed "makefile.std" to "makefile", since there
+ is only one makefile in those directories, and revised the README files
+ accordingly.
+ More reformatting of comments, mostly to capitalize sentences.
+
+Version 1.4.0beta62 [June 2, 2009]
+ Added "#define PNG_NO_WRITE_SWAP" to contrib/pngminim/encoder/pngusr.h
+ and "define PNG_NO_READ_SWAP" to decoder/pngusr.h and preader/pngusr.h
+ Reformatted several remaining "else statement" into two lines.
+ Added a section to the libpng documentation about using png_get_io_ptr()
+ in configure scripts to detect the presence of libpng.
+
+Version 1.4.0beta63 [June 15, 2009]
+ Revised libpng*.txt and libpng.3 to mention calling png_set_IHDR()
+ multiple times and to specify the sample order in the tRNS chunk,
+ because the ISO PNG specification has a typo in the tRNS table.
+ Changed several PNG_UNKNOWN_CHUNK_SUPPORTED to
+ PNG_HANDLE_AS_UNKNOWN_SUPPORTED, to make the png_set_keep mechanism
+ available for ignoring known chunks even when not saving unknown chunks.
+ Adopted preference for consistent use of "#ifdef" and "#ifndef" versus
+ "#if defined()" and "if !defined()" where possible.
+
+Version 1.4.0beta64 [June 24, 2009]
+ Eliminated PNG_LEGACY_SUPPORTED code.
+ Moved the various unknown chunk macro definitions outside of the
+ PNG_READ|WRITE_ANCILLARY_CHUNK_SUPPORTED blocks.
+
+Version 1.4.0beta65 [June 26, 2009]
+ Added a reference to the libpng license in each file.
+
+Version 1.4.0beta66 [June 27, 2009]
+ Refer to the libpng license instead of the libpng license in each file.
+
+Version 1.4.0beta67 [July 6, 2009]
+ Relocated INVERT_ALPHA within png_read_png() and png_write_png().
+ Added high-level API transform PNG_TRANSFORM_GRAY_TO_RGB.
+ Added an "xcode" project to the projects directory (Alam Arias).
+
+Version 1.4.0beta68 [July 19, 2009]
+ Avoid some tests in filter selection in pngwutil.c
+
+Version 1.4.0beta69 [July 25, 2009]
+ Simplified the new filter-selection test. This runs faster in the
+ common "PNG_ALL_FILTERS" and PNG_FILTER_NONE cases.
+ Removed extraneous declaration from the new call to png_read_gray_to_rgb()
+ (bug introduced in libpng-1.4.0beta67).
+ Fixed up xcode project (Alam Arias)
+ Added a prototype for png_64bit_product() in png.c
+
+Version 1.4.0beta70 [July 27, 2009]
+ Avoid a possible NULL dereference in debug build, in png_set_text_2().
+ (bug introduced in libpng-0.95, discovered by Evan Rouault)
+
+Version 1.4.0beta71 [July 29, 2009]
+ Rebuilt configure scripts with autoconf-2.64.
+
+Version 1.4.0beta72 [August 1, 2009]
+ Replaced *.tar.lzma with *.tar.xz in distribution. Get the xz codec
+ from <http://tukaani.org/xz>.
+
+Version 1.4.0beta73 [August 1, 2009]
+ Reject attempt to write iCCP chunk with negative embedded profile length
+ (JD Chen) (CVE-2009-5063).
+
+Version 1.4.0beta74 [August 8, 2009]
+ Changed png_ptr and info_ptr member "trans" to "trans_alpha".
+
+Version 1.4.0beta75 [August 21, 2009]
+ Removed an extra png_debug() recently added to png_write_find_filter().
+ Fixed incorrect #ifdef in pngset.c regarding unknown chunk support.
+
+Version 1.4.0beta76 [August 22, 2009]
+ Moved an incorrectly located test in png_read_row() in pngread.c
+
+Version 1.4.0beta77 [August 27, 2009]
+ Removed lpXYZ.tar.bz2 (with CRLF), KNOWNBUG, libpng-x.y.z-KNOWNBUG.txt,
+ and the "noconfig" files from the distribution.
+ Moved CMakeLists.txt from scripts into the main libpng directory.
+ Various bugfixes and improvements to CMakeLists.txt (Philip Lowman)
+
+Version 1.4.0beta78 [August 31, 2009]
+ Converted all PNG_NO_* tests to PNG_*_SUPPORTED everywhere except pngconf.h
+ Eliminated PNG_NO_FREE_ME and PNG_FREE_ME_SUPPORTED macros.
+ Use png_malloc plus a loop instead of png_calloc() to initialize
+ row_pointers in png_read_png().
+
+Version 1.4.0beta79 [September 1, 2009]
+ Eliminated PNG_GLOBAL_ARRAYS and PNG_LOCAL_ARRAYS; always use local arrays.
+ Eliminated PNG_CALLOC_SUPPORTED macro and always provide png_calloc().
+
+Version 1.4.0beta80 [September 17, 2009]
+ Removed scripts/libpng.icc
+ Changed typecast of filler from png_byte to png_uint_16 in png_set_filler().
+ (Dennis Gustafsson)
+ Fixed typo introduced in beta78 in pngtest.c ("#if def " should be "#ifdef ")
+
+Version 1.4.0beta81 [September 23, 2009]
+ Eliminated unused PNG_FLAG_FREE_* defines from pngpriv.h
+ Expanded TAB characters in pngrtran.c
+ Removed PNG_CONST from all "PNG_CONST PNG_CHNK" declarations to avoid
+ compiler complaints about doubly declaring things "const".
+ Changed all "#if [!]defined(X)" to "if[n]def X" where possible.
+ Eliminated unused png_ptr->row_buf_size
+
+Version 1.4.0beta82 [September 25, 2009]
+ Moved redundant IHDR checking into new png_check_IHDR() in png.c
+ and report all errors found in the IHDR data.
+ Eliminated useless call to png_check_cHRM() from pngset.c
+
+Version 1.4.0beta83 [September 25, 2009]
+ Revised png_check_IHDR() to eliminate bogus complaint about filter_type.
+
+Version 1.4.0beta84 [September 30, 2009]
+ Fixed some inconsistent indentation in pngconf.h
+ Revised png_check_IHDR() to add a test for width variable less than 32-bit.
+
+Version 1.4.0beta85 [October 1, 2009]
+ Revised png_check_IHDR() again, to check info_ptr members instead of
+ the contents of the returned parameters.
+
+Version 1.4.0beta86 [October 9, 2009]
+ Updated the "xcode" project (Alam Arias).
+ Eliminated a shadowed declaration of "pp" in png_handle_sPLT().
+
+Version 1.4.0rc01 [October 19, 2009]
+ Trivial cosmetic changes.
+
+Version 1.4.0beta87 [October 30, 2009]
+ Moved version 1.4.0 back into beta.
+
+Version 1.4.0beta88 [October 30, 2009]
+ Revised libpng*.txt section about differences between 1.2.x and 1.4.0
+ because most of the new features have now been ported back to 1.2.41
+
+Version 1.4.0beta89 [November 1, 2009]
+ More bugfixes and improvements to CMakeLists.txt (Philip Lowman)
+ Removed a harmless extra png_set_invert_alpha() from pngwrite.c
+ Apply png_user_chunk_cache_max within png_decompress_chunk().
+ Merged libpng-1.2.41.txt with libpng-1.4.0.txt where appropriate.
+
+Version 1.4.0beta90 [November 2, 2009]
+ Removed all remaining WIN32_WCE #ifdefs except those involving the
+ time.h "tm" structure
+
+Version 1.4.0beta91 [November 3, 2009]
+ Updated scripts/pngw32.def and projects/wince/png32ce.def
+ Copied projects/wince/png32ce.def to the scripts directory.
+ Added scripts/makefile.wce
+ Patched ltmain.sh for wince support.
+ Added PNG_CONVERT_tIME_SUPPORTED macro.
+
+Version 1.4.0beta92 [November 4, 2009]
+ Make inclusion of time.h in pngconf.h depend on PNG_CONVERT_tIME_SUPPORTED
+ Make #define PNG_CONVERT_tIME_SUPPORTED depend on PNG_WRITE_tIME_SUPPORTED
+ Revised libpng*.txt to describe differences from 1.2.40 to 1.4.0 (instead
+ of differences from 1.2.41 to 1.4.0)
+
+Version 1.4.0beta93 [November 7, 2009]
+ Added PNG_DEPSTRUCT, PNG_DEPRECATED, PNG_USE_RESULT, PNG_NORETURN, and
+ PNG_ALLOCATED macros to detect deprecated direct access to the
+ png_struct or info_struct members and other deprecated usage in
+ applications (John Bowler).
+ Updated scripts/makefile* to add "-DPNG_CONFIGURE_LIBPNG" to CFLAGS,
+ to prevent warnings about direct access to png structs by libpng
+ functions while building libpng. They need to be tested, especially
+ those using compilers other than gcc.
+ Updated projects/visualc6 and visualc71 with "/d PNG_CONFIGURE_LIBPNG".
+ They should work but still need to be updated to remove
+ references to pnggccrd.c or pngvcrd.c and ASM building.
+ Added README.txt to the beos, cbuilder5, netware, and xcode projects warning
+ that they need to be updated, to remove references to pnggccrd.c and
+ pngvcrd.c and to depend on pngpriv.h
+ Removed three direct references to read_info_ptr members in pngtest.c
+ that were detected by the new PNG_DEPSTRUCT macro.
+ Moved the png_debug macro definitions and the png_read_destroy(),
+ png_write_destroy() and png_far_to_near() prototypes from png.h
+ to pngpriv.h (John Bowler)
+ Moved the synopsis lines for png_read_destroy(), png_write_destroy()
+ png_debug(), png_debug1(), and png_debug2() from libpng.3 to libpngpf.3.
+
+Version 1.4.0beta94 [November 9, 2009]
+ Removed the obsolete, unused pnggccrd.c and pngvcrd.c files.
+ Updated CMakeLists.txt to add "-DPNG_CONFIGURE_LIBPNG" to the definitions.
+ Removed dependency of pngtest.o on pngpriv.h in the makefiles.
+ Only #define PNG_DEPSTRUCT, etc. in pngconf.h if not already defined.
+
+Version 1.4.0beta95 [November 10, 2009]
+ Changed png_check_sig() to !png_sig_cmp() in contrib programs.
+ Added -DPNG_CONFIGURE_LIBPNG to contrib/pngminm/*/makefile
+ Changed png_check_sig() to !png_sig_cmp() in contrib programs.
+ Corrected the png_get_IHDR() call in contrib/gregbook/readpng2.c
+ Changed pngminim/*/gather.sh to stop trying to remove pnggccrd.c and pngvcrd.c
+ Added dependency on pngpriv.h in contrib/pngminim/*/makefile
+
+Version 1.4.0beta96 [November 12, 2009]
+ Renamed scripts/makefile.wce to scripts/makefile.cegcc
+ Revised Makefile.am to use libpng.sys while building libpng.so
+ so that only PNG_EXPORT functions are exported.
+ Removed the deprecated png_check_sig() function/macro.
+ Removed recently removed function names from scripts/*.def
+ Revised pngtest.png to put chunks in the same order written by pngtest
+ (evidently the same change made in libpng-1.0beta54 was lost).
+ Added PNG_PRIVATE macro definition in pngconf.h for possible future use.
+
+Version 1.4.0beta97 [November 13, 2009]
+ Restored pngtest.png to the libpng-1.4.0beta7 version.
+ Removed projects/beos and netware.txt; no one seems to be supporting them.
+ Revised Makefile.in
+
+Version 1.4.0beta98 [November 13, 2009]
+ Added the "xcode" project to zip distributions,
+ Fixed a typo in scripts/pngwin.def introduced in beta97.
+
+Version 1.4.0beta99 [November 14, 2009]
+ Moved libpng-config.in and libpng.pc-configure.in out of the scripts
+ directory, to libpng-config.in and libpng-pc.in, respectively, and
+ modified Makefile.am and configure.ac accordingly. Now "configure"
+ needs nothing from the "scripts" directory.
+ Avoid redefining PNG_CONST in pngconf.h
+
+Version 1.4.0beta100 [November 14, 2009]
+ Removed ASM builds from projects/visualc6 and projects/visualc71
+ Removed scripts/makefile.nommx and makefile.vcawin32
+ Revised CMakeLists.txt to account for new location of libpng-config.in
+ and libpng-pc.in
+ Updated INSTALL to reflect removal and relocation of files.
+
+Version 1.4.0beta101 [November 14, 2009]
+ Restored the binary files (*.jpg, *.png, some project files) that were
+ accidentally deleted from the zip and 7z distributions when the xcode
+ project was added.
+
+Version 1.4.0beta102 [November 18, 2009]
+ Added libpng-config.in and libpng-pc.in to the zip and 7z distributions.
+ Fixed a typo in projects/visualc6/pngtest.dsp, introduced in beta100.
+ Moved descriptions of makefiles and other scripts out of INSTALL into
+ scripts/README.txt
+ Updated the copyright year in scripts/pngwin.rc from 2006 to 2009.
+
+Version 1.4.0beta103 [November 21, 2009]
+ Removed obsolete comments about ASM from projects/visualc71/README_zlib.txt
+ Align row_buf on 16-byte boundary in memory.
+ Restored the PNG_WRITE_FLUSH_AFTER_IEND_SUPPORTED guard around the call
+ to png_flush() after png_write_IEND(). See 1.4.0beta32, 1.4.0beta50
+ changes above and 1.2.30, 1.2.30rc01 and rc03 in 1.2.41 CHANGES. Someone
+ needs this feature.
+ Make the 'png_jmpbuf' macro expand to a call that records the correct
+ longjmp function as well as returning a pointer to the setjmp
+ jmp_buf buffer, and marked direct access to jmpbuf 'deprecated'.
+ (John Bowler)
+
+Version 1.4.0beta104 [November 22, 2009]
+ Removed png_longjmp_ptr from scripts/*.def and libpng.3
+ Rebuilt configure scripts with autoconf-2.65
+
+Version 1.4.0beta105 [November 25, 2009]
+ Use fast integer PNG_DIVIDE_BY_255() or PNG_DIVIDE_BY_65535()
+ to accomplish alpha premultiplication when
+ PNG_READ_COMPOSITE_NODIV_SUPPORTED is defined.
+ Changed "/255" to "/255.0" in background calculations to make it clear
+ that the 255 is used as a double.
+
+Version 1.4.0beta106 [November 27, 2009]
+ Removed premultiplied alpha feature.
+
+Version 1.4.0beta107 [December 4, 2009]
+ Updated README
+ Added "#define PNG_NO_PEDANTIC_WARNINGS" in the libpng source files.
+ Removed "-DPNG_CONFIGURE_LIBPNG" from the makefiles and projects.
+ Revised scripts/makefile.netbsd, makefile.openbsd, and makefile.sco
+ to put png.h and pngconf.h in $prefix/include, like the other scripts,
+ instead of in $prefix/include/libpng. Also revised makefile.sco
+ to put them in $prefix/include/libpng15 instead of in
+ $prefix/include/libpng/libpng15.
+
+Version 1.4.0beta108 [December 11, 2009]
+ Removed leftover "-DPNG_CONFIGURE_LIBPNG" from contrib/pngminim/*/makefile
+ Relocated png_do_chop() to its original position in pngrtran.c; the
+ change in version 1.2.41beta08 caused transparency to be handled wrong
+ in some 16-bit datastreams (Yusaku Sugai).
+
+Version 1.4.0beta109 [December 13, 2009]
+ Added "bit_depth" parameter to the private png_build_gamma_table() function.
+ Pass bit_depth=8 to png_build_gamma_table() when bit_depth is 16 but the
+ PNG_16_TO_8 transform has been set, to avoid unnecessary build of 16-bit
+ tables.
+
+Version 1.4.0rc02 [December 20, 2009]
+ Declared png_cleanup_needed "volatile" in pngread.c and pngwrite.c
+
+Version 1.4.0rc03 [December 22, 2009]
+ Renamed libpng-pc.in back to libpng.pc.in and revised CMakeLists.txt
+ (revising the change in 1.4.0beta99)
+
+Version 1.4.0rc04 [December 25, 2009]
+ Swapped PNG_UNKNOWN_CHUNKS_SUPPORTED and PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+ in pngset.c to be consistent with other changes in version 1.2.38.
+
+Version 1.4.0rc05 [December 25, 2009]
+ Changed "libpng-pc.in" to "libpng.pc.in" in configure.ac, configure, and
+ Makefile.in to be consistent with changes in libpng-1.4.0rc03
+
+Version 1.4.0rc06 [December 29, 2009]
+ Reverted the gamma_table changes from libpng-1.4.0beta109.
+ Fixed some indentation errors.
+
+Version 1.4.0rc07 [January 1, 2010]
+ Revised libpng*.txt and libpng.3 about 1.2.x->1.4.x differences.
+ Use png_calloc() instead of png_malloc(); png_memset() in pngrutil.c
+ Update copyright year to 2010.
+
+Version 1.4.0rc08 [January 2, 2010]
+ Avoid deprecated references to png_ptr-io_ptr and png_ptr->error_ptr
+ in pngtest.c
+
+Version 1.4.0 [January 3, 2010]
+ No changes.
+
+Version 1.4.1beta01 [January 8, 2010]
+ Updated CMakeLists.txt for consistent indentation and to avoid an
+ unclosed if-statement warning (Philip Lowman).
+ Revised Makefile.am and Makefile.in to remove references to Y2KINFO,
+ KNOWNBUG, and libpng.la (Robert Schwebel).
+ Revised the makefiles to install the same files and symbolic
+ links as configure, except for libpng.la and libpng14.la.
+ Make png_set|get_compression_buffer_size() available even when
+ PNG_WRITE_SUPPORTED is not enabled.
+ Revised Makefile.am and Makefile.in to simplify their maintenance.
+ Revised scripts/makefile.linux to install a link to libpng14.so.14.1
+
+Version 1.4.1beta02 [January 9, 2010]
+ Revised the rest of the makefiles to install a link to libpng14.so.14.1
+
+Version 1.4.1beta03 [January 10, 2010]
+ Removed png_set_premultiply_alpha() from scripts/*.def
+
+Version 1.4.1rc01 [January 16, 2010]
+ No changes.
+
+Version 1.4.1beta04 [January 23, 2010]
+ Revised png_decompress_chunk() to improve speed and memory usage when
+ decoding large chunks.
+ Added png_set|get_chunk_malloc_max() functions.
+
+Version 1.4.1beta05 [January 26, 2010]
+ Relocated "int k" declaration in pngtest.c to minimize its scope.
+
+Version 1.4.1beta06 [January 28, 2010]
+ Revised png_decompress_chunk() to use a two-pass method suggested by
+ John Bowler.
+
+Version 1.4.1beta07 [February 6, 2010]
+ Folded some long lines in the source files.
+ Added defineable PNG_USER_CHUNK_CACHE_MAX, PNG_USER_CHUNK_MALLOC_MAX,
+ and a PNG_USER_LIMITS_SUPPORTED flag.
+ Eliminated use of png_ptr->irowbytes and reused the slot in png_ptr as
+ png_ptr->png_user_chunk_malloc_max.
+ Revised png_push_save_buffer() to do fewer but larger png_malloc() calls.
+
+Version 1.4.1beta08 [February 6, 2010]
+ Minor cleanup and updating of dates and copyright year.
+
+Version 1.5.0beta01 [February 7, 2010]
+ Moved declaration of png_struct into private pngstruct.h and png_info
+ into pnginfo.h
+
+Version 1.4.1beta09 and 1.5.0beta02 [February 7, 2010]
+ Reverted to original png_push_save_buffer() code.
+
+Version 1.4.1beta10 and 1.5.0beta03 [February 8, 2010]
+ Return allocated "old_buffer" in png_push_save_buffer() before
+ calling png_error(), to avoid a potential memory leak.
+ Updated configure script to use SO number 15.
+
+Version 1.5.0beta04 [February 9, 2010]
+ Removed malformed "incomplete struct declaration" of png_info from png.h
+
+Version 1.5.0beta05 [February 12, 2010]
+ Removed PNG_DEPSTRUCT markup in pngstruct.h and pnginfo.h, and undid the
+ linewrapping that it entailed.
+ Revised comments in pngstruct.h and pnginfo.h and added pointers to
+ the libpng license.
+ Changed PNG_INTERNAL to PNG_EXPOSE_INTERNAL_STRUCTURES
+ Removed the cbuilder5 project, which has not been updated to 1.4.0.
+
+Version 1.4.1beta12 and 1.5.0beta06 [February 14, 2010]
+ Fixed type declaration of png_get_chunk_malloc_max() in pngget.c (Daisuke
+ Nishikawa)
+
+Version 1.5.0beta07 [omitted]
+
+Version 1.5.0beta08 [February 19, 2010]
+ Changed #ifdef PNG_NO_STDIO_SUPPORTED to #ifdef PNG_NO_CONSOLE_IO_SUPPORTED
+ wherever png_snprintf() is used to construct error and warning messages.
+ Noted in scripts/makefile.mingw that it expects to be run under MSYS.
+ Removed obsolete unused MMX-querying support from contrib/gregbook
+ Added exported png_longjmp() function.
+ Removed the AIX redefinition of jmpbuf in png.h
+ Added -D_ALLSOURCE in configure.ac, makefile.aix, and CMakeLists.txt
+ when building on AIX.
+
+Version 1.5.0beta09 [February 19, 2010]
+ Removed -D_ALLSOURCE from configure.ac, makefile.aix, and CMakeLists.txt.
+ Changed the name of png_ptr->jmpbuf to png_ptr->png_jmpbuf in pngstruct.h
+
+Version 1.5.0beta10 [February 25, 2010]
+ Removed unused gzio.c from contrib/pngminim gather and makefile scripts
+ Removed replacement error handlers from contrib/gregbook. Because of
+ the new png_longjmp() function they are no longer needed.
+
+Version 1.5.0beta11 [March 6, 2010]
+ Removed checking for already-included setjmp.h from pngconf.h
+ Fixed inconsistent indentations and made numerous cosmetic changes.
+ Revised the "SEE ALSO" style of libpng.3, libpngpf.3, and png.5
+
+Version 1.5.0beta12 [March 9, 2010]
+ Moved "#include png.h" inside pngpriv.h and removed "#include png.h" from
+ the source files, along with "#define PNG_EXPOSE_INTERNAL_STRUCTURES"
+ and "#define PNG_NO_PEDANTIC_WARNINGS" (John Bowler).
+ Created new pngdebug.h and moved debug definitions there.
+
+Version 1.5.0beta13 [March 10, 2010]
+ Protect pngstruct.h, pnginfo.h, and pngdebug.h from being included twice.
+ Revise the "#ifdef" blocks in png_inflate() so it will compile when neither
+ PNG_USER_CHUNK_MALLOC_MAX nor PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
+ is defined.
+ Removed unused png_measure_compressed_chunk() from pngpriv.h and libpngpf.3
+ Moved the 'config.h' support from pngconf.h to pngpriv.h
+ Removed PNGAPI from the png_longjmp_ptr typedef.
+ Eliminated dependence of pngtest.c on the private pngdebug.h file.
+ Make all png_debug macros into *unterminated* statements or
+ expressions (i.e. a trailing ';' must always be added) and correct
+ the format statements in various png_debug messages.
+
+Version 1.5.0beta14 [March 14, 2010]
+ Removed direct access to png_ptr->io_ptr from the Windows code in pngtest.c
+ Revised Makefile.am to account for recent additions and replacements.
+ Corrected CE and OS/2 DEF files (scripts/png*def) for symbols removed and
+ added ordinal numbers to the Windows DEF file and corrected the duplicated
+ ordinal numbers on CE symbols that are commented out.
+ Added back in export symbols that can be present in the Windows build but
+ are disabled by default.
+ PNG_EXPORT changed to include an 'ordinal' field for DEF file generation.
+ PNG_CALLBACK added to make callback definitions uniform. PNGAPI split
+ into PNGCAPI (base C form), PNGAPI (exports) and PNGCBAPI (callbacks),
+ and appropriate changes made to all files. Cygwin builds re-hinged to
+ allow procedure call standard changes and to remove the need for the DEF
+ file (fixes build on Cygwin).
+ Enabled 'attribute' warnings that are relevant to library APIs and callbacks.
+ Changed rules for generation of the various symbol files and added a new
+ rule for a DEF file (which is also added to the distribution).
+ Updated the symbol file generation to stop it adding spurious spaces
+ to EOL (coming from preprocessor macro expansion). Added a facility
+ to join tokens in the output and rewrite *.dfn to use this.
+ Eliminated scripts/*.def in favor of libpng.def; updated projects/visualc71
+ and removed scripts/makefile.cygwin.
+ Made PNG_BUILD_DLL safe: it can be set whenever a DLL is being built.
+ Removed the include of sys/types.h - apparently unnecessary now on the
+ platforms on which it happened (all but Mac OS and RISC OS).
+ Moved the Mac OS test into pngpriv.h (the only place it is used.)
+
+Version 1.5.0beta15 [March 17, 2010]
+ Added symbols.chk target to Makefile.am to validate the symbols in png.h
+ against the new DEF file scripts/symbols.def.
+ Changed the default DEF file back to pngwin.def.
+ Removed makefile.mingw.
+ Eliminated PNG_NO_EXTERN and PNG_ALL_EXTERN
+
+Version 1.5.0beta16 [April 1, 2010]
+ Make png_text_struct independent of PNG_iTXt_SUPPORTED, so that
+ fields are initialized in all configurations. The READ/WRITE
+ macros (PNG_(READ|WRITE)_iTXt_SUPPORTED) still function as
+ before to disable code to actually read or write iTXt chunks
+ and iTXt_SUPPORTED can be used to detect presence of either
+ read or write support (but it is probably better to check for
+ the one actually required - read or write.)
+ Combined multiple png_warning() calls for a single error.
+ Restored the macro definition of png_check_sig().
+
+Version 1.5.0beta17 [April 17, 2010]
+ Added some "(long)" typecasts to printf calls in png_handle_cHRM().
+ Documented the fact that png_set_dither() was disabled since libpng-1.4.0.
+ Reenabled png_set_dither() but renamed it to png_set_quantize() to reflect
+ more accurately what it actually does. At the same time, renamed
+ the PNG_DITHER_[RED,GREEN_BLUE]_BITS macros to
+ PNG_QUANTIZE_[RED,GREEN,BLUE]_BITS.
+ Added some "(long)" typecasts to printf calls in png_handle_cHRM().
+ Freeze build-time only configuration in the build.
+ In all prior versions of libpng most configuration options
+ controlled by compiler #defines had to be repeated by the
+ application code that used libpng. This patch changes this
+ so that compilation options that can only be changed at build
+ time are frozen in the build. Options that are compiler
+ dependent (and those that are system dependent) are evaluated
+ each time - pngconf.h holds these. Options that can be changed
+ per-file in the application are in png.h. Frozen options are
+ in the new installed header file pnglibconf.h (John Bowler)
+ Removed the xcode project because it has not been updated to work
+ with libpng-1.5.0.
+ Removed the ability to include optional pngusr.h
+
+Version 1.5.0beta18 [April 17, 2010]
+ Restored the ability to include optional pngusr.h
+ Moved replacements for png_error() and png_warning() from the
+ contrib/pngminim project to pngerror.c, for use when warnings or
+ errors are disabled via PNG_NO_WARN or PNG_NO_ERROR_TEXT, to avoid
+ storing unneeded error/warning text.
+ Updated contrib/pngminim project to work with the new pnglibconf.h
+ Added some PNG_NO_* defines to contrib/pngminim/*/pngusr.h to save space.
+
+Version 1.5.0beta19 [April 24, 2010]
+ Added PNG_{READ,WRITE}_INT_FUNCTIONS_SUPPORTED. This allows the functions
+ to read and write ints to be disabled independently of PNG_USE_READ_MACROS,
+ which allows libpng to be built with the functions even though the default
+ is to use the macros - this allows applications to choose at app build
+ time whether or not to use macros (previously impossible because the
+ functions weren't in the default build.)
+ Changed Windows calling convention back to __cdecl for API functions.
+ For Windows/x86 platforms only:
+ __stdcall is no longer needed for Visual Basic, so libpng-1.5.0 uses
+ __cdecl throughout (both API functions and callbacks) on Windows/x86
+ platforms.
+ Replaced visualc6 and visualc71 projects with new vstudio project
+ Relaxed the overly-restrictive permissions of some files.
+
+Version 1.5.0beta20 [April 24, 2010]
+ Relaxed more overly-restrictive permissions of some files.
+
+Version 1.5.0beta21 [April 27, 2010]
+ Removed some unwanted binary bytes and changed CRLF to NEWLINE in the new
+ vstudio project files, and some trivial editing of some files in the
+ scripts directory.
+ Set PNG_NO_READ_BGR, PNG_NO_IO_STATE, and PNG_NO_TIME_RFC1123 in
+ contrib/pngminim/decoder/pngusr.h to make a smaller decoder application.
+
+Version 1.5.0beta22 [April 28, 2010]
+ Fixed dependencies of GET_INT_32 - it does not require READ_INT_FUNCTIONS
+ because it has a macro equivalent.
+ Improved the options.awk script; added an "everything off" option.
+ Revised contrib/pngminim to use the "everything off" option in pngusr.dfa.
+
+Version 1.5.0beta23 [April 29, 2010]
+ Corrected PNG_REMOVED macro to take five arguments.
+ The macro was documented with two arguments (name,ordinal), however
+ the symbol checking .dfn files assumed five arguments. The five
+ argument form seems more useful so it is changed to that.
+ Corrected PNG_UNKNOWN_CHUNKS_SUPPORTED to PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+ in gregbook/readpng2.c
+ Corrected protection of png_get_user_transform_ptr. The API declaration in
+ png.h is removed if both READ and WRITE USER_TRANSFORM are turned off
+ but was left defined in pngtrans.c
+ Added logunsupported=1 to cause pnglibconf.h to document disabled options.
+ This makes the installed pnglibconf.h more readable but causes no
+ other change. The intention is that users of libpng will find it
+ easier to understand if an API they need is missing.
+ Include png_reset_zstream() in png.c only when PNG_READ_SUPPORTED is defined.
+ Removed dummy_inflate.c from contrib/pngminim/encoder
+ Removed contrib/pngminim/*/gather.sh; gathering is now done in the makefile.
+
+Version 1.5.0beta24 [May 7, 2010]
+ Use bitwise "&" instead of arithmetic mod in pngrutil.c calculation of the
+ offset of the png_ptr->rowbuf pointer into png_ptr->big_row_buf.
+ Added more blank lines for readability.
+
+Version 1.5.0beta25 [June 18, 2010]
+ In pngpread.c: png_push_have_row() add check for new_row > height
+ Removed the now-redundant check for out-of-bounds new_row from example.c
+
+Version 1.5.0beta26 [June 18, 2010]
+ In pngpread.c: png_push_process_row() add check for too many rows.
+
+Version 1.5.0beta27 [June 18, 2010]
+ Removed the check added in beta25 as it is now redundant.
+
+Version 1.5.0beta28 [June 20, 2010]
+ Rewrote png_process_IDAT_data to consistently treat extra data as warnings
+ and handle end conditions more cleanly.
+ Removed the new (beta26) check in png_push_process_row().
+
+Version 1.5.0beta29 [June 21, 2010]
+ Revised scripts/options.awk to work on Sunos (but still doesn't work)
+ Added comment to options.awk and contrib/pngminim/*/makefile to try nawk.
+
+Version 1.5.0beta30 [June 22, 2010]
+ Stop memory leak when reading a malformed sCAL chunk.
+
+Version 1.5.0beta31 [June 26, 2010]
+ Revised pngpread.c patch of beta28 to avoid an endless loop.
+ Removed some trailing blanks.
+
+Version 1.5.0beta32 [June 26, 2010]
+ Removed leftover scripts/options.patch and scripts/options.rej
+
+Version 1.5.0beta33 [July 6, 3010]
+ Made FIXED and FLOATING options consistent in the APIs they enable and
+ disable. Corrected scripts/options.awk to handle both command line
+ options and options specified in the .dfa files.
+ Changed char *msg to PNG_CONST char *msg in pngrutil.c
+ Make png_set_sRGB_gAMA_and_cHRM set values using either the fixed or
+ floating point APIs, but not both.
+ Reversed patch to remove error handler when the jmp_buf is stored in the
+ main program structure, not the png_struct.
+ The error handler is needed because the default handler in libpng will
+ always use the jmp_buf in the library control structure; this is never
+ set. The gregbook code is a useful example because, even though it
+ uses setjmp/longjmp, it shows how error handling can be implemented
+ using control mechanisms not directly supported by libpng. The
+ technique will work correctly with mechanisms such as Microsoft
+ Structure Exceptions or C++ exceptions (compiler willing - note that gcc
+ does not by default support interworking of C and C++ error handling.)
+ Reverted changes to call png_longjmp in contrib/gregbook where it is not
+ appropriate. If mainprog->jmpbuf is used by setjmp, then png_longjmp
+ cannot be used.
+ Changed "extern PNG_EXPORT" to "PNG_EXPORT" in png.h (Jan Nijtmans)
+ Changed "extern" to "PNG_EXTERN" in pngpriv.h (except for the 'extern "C" {')
+
+Version 1.5.0beta34 [July 12, 2010]
+ Put #ifndef PNG_EXTERN, #endif around the define PNG_EXTERN in pngpriv.h
+
+Version 1.5.0beta35 [July 24, 2010]
+ Removed some newly-added TAB characters.
+ Added -DNO_PNG_SNPRINTF to CFLAGS in scripts/makefile.dj2
+ Moved the definition of png_snprintf() outside of the enclosing
+ #ifdef blocks in pngconf.h
+
+Version 1.5.0beta36 [July 29, 2010]
+ Patches by John Bowler:
+ Fixed point APIs are now supported throughout (no missing APIs).
+ Internal fixed point arithmetic support exists for all internal floating
+ point operations.
+ sCAL validates the floating point strings it is passed.
+ Safe, albeit rudimentary, Watcom support is provided by PNG_API_RULE==2
+ Two new APIs exist to get the number of passes without turning on the
+ PNG_INTERLACE transform and to get the number of rows in the current
+ pass.
+ A new test program, pngvalid.c, validates the gamma code.
+ Errors in the 16-bit gamma correction (overflows) have been corrected.
+ cHRM chunk testing is done consistently (previously the floating point
+ API bypassed it, because the test really didn't work on FP, now the test
+ is performed on the actual values to be stored in the PNG file so it
+ works in the FP case too.)
+ Most floating point APIs now simply call the fixed point APIs after
+ converting the values to the fixed point form used in the PNG file.
+ The standard headers no longer include zlib.h, which is currently only
+ required for pngstruct.h and can therefore be internal.
+ Revised png_get_int_32 to undo the PNG two's complement representation of
+ negative numbers.
+
+Version 1.5.0beta37 [July 30, 2010]
+ Added a typecast in png_get_int_32() in png.h and pngrutil.h to avoid
+ a compiler warning.
+ Replaced oFFs 0,0 with oFFs -10,20 in pngtest.png
+
+Version 1.5.0beta38 [July 31, 2010]
+ Implemented remaining "_fixed" functions.
+ Corrected a number of recently introduced warnings mostly resulting from
+ safe but uncast assignments to shorter integers. Also added a zlib
+ VStudio release library project because the latest zlib Official Windows
+ build does not include such a thing.
+ Revised png_get_int_16() to be similar to png_get_int_32().
+ Restored projects/visualc71.
+
+Version 1.5.0beta39 [August 2, 2010]
+ VisualC/GCC warning fixes, VisualC build fixes
+ The changes include support for function attributes in VC in addition to
+ those already present in GCC - necessary because without these some
+ warnings are unavoidable. Fixes include signed/unsigned fixes in
+ pngvalid and checks with gcc -Wall -Wextra -Wunused.
+ VC requires function attributes on function definitions as well as
+ declarations, PNG_FUNCTION has been added to enable this and the
+ relevant function definitions changed.
+
+Version 1.5.0beta40 [August 6, 2010]
+ Correct use of _WINDOWS_ in pngconf.h
+ Removed png_mem_ #defines; they are no longer used.
+ Added the sRGB chunk to pngtest.png
+
+Version 1.5.0beta41 [August 11, 2010]
+ Added the cHRM chunk to pngtest.png
+ Don't try to use version-script with cygwin/mingw.
+ Revised contrib/gregbook to work under cygwin/mingw.
+
+Version 1.5.0beta42 [August 18, 2010]
+ Add .dll.a to the list of extensions to be symlinked by Makefile.am (Yaakov)
+ Made all API functions that have const arguments and constant string
+ literal pointers declare them (John Bowler).
+
+Version 1.5.0beta43 [August 20, 2010]
+ Removed spurious tabs, shorten long lines (no source change)
+ Also added scripts/chkfmt to validate the format of all the files that can
+ reasonably be validated (it is suggested to run "make distclean" before
+ checking, because some machine generated files have long lines.)
+ Reformatted the CHANGES file to be more consistent throughout.
+ Made changes to address various issues identified by GCC, mostly
+ signed/unsigned and shortening problems on assignment but also a few
+ difficult to optimize (for GCC) loops.
+ Fixed non-GCC fixed point builds. In png.c a declaration was misplaced
+ in an earlier update. Fixed to declare the auto variables at the head.
+ Use cexcept.h in pngvalid.c.
+
+Version 1.5.0beta44 [August 24, 2010]
+ Updated CMakeLists.txt to use CMAKE_INSTALL_LIBDIR variable; useful for
+ installing libpng in /usr/lib64 (Funda Wang).
+ Revised CMakeLists.txt to put the man pages in share/man/man* not man/man*
+ Revised CMakeLists.txt to make symlinks instead of copies when installing.
+ Changed PNG_LIB_NAME from pngNN to libpngNN in CMakeLists.txt (Philip Lowman)
+ Implemented memory checks within pngvalid
+ Reformatted/rearranged pngvalid.c to assist use of progressive reader.
+ Check interlaced images in pngvalid
+ Clarified pngusr.h comments in pnglibconf.dfa
+ Simplified the pngvalid error-handling code now that cexcept.h is in place.
+ Implemented progressive reader in pngvalid.c for standard tests
+ Implemented progressive read in pngvalid.c gamma tests
+ Turn on progressive reader in pngvalid.c by default and tidy code.
+
+Version 1.5.0beta45 [August 26, 2010]
+ Added an explicit make step to projects/vstudio for pnglibconf.h
+ Also corrected zlib.vcxproj into which Visual Studio had introduced
+ what it calls an "authoring error". The change to make pnglibconf.h
+ simply copies the file; in the future it may actually generate the
+ file from scripts/pnglibconf.dfa as the other build systems do.
+ Changed pngvalid to work when floating point APIs are disabled
+ Renamed the prebuilt scripts/pnglibconf.h to scripts/pnglibconf.h.prebuilt
+ Supply default values for PNG_USER_PRIVATEBUILD and PNG_USER_DLLFNAME_POSTFIX
+ in pngpriv.h in case the user neglected to define them in their pngusr.h
+
+Version 1.5.0beta46 [August 28, 2010]
+ Added new private header files to libpng_sources in CMakeLists.txt
+ Added PNG_READ_16BIT, PNG_WRITE_16BIT, and PNG_16BIT options.
+ Added reference to scripts/pnglibconf.h.prebuilt in the visualc71 project.
+
+Version 1.5.0beta47 [September 11, 2010]
+ Fixed a number of problems with 64-bit compilation reported by Visual
+ Studio 2010 (John Bowler).
+
+Version 1.5.0beta48 [October 4, 2010]
+ Updated CMakeLists.txt (Philip Lowman).
+ Revised autogen.sh to recognize and use $AUTOCONF, $AUTOMAKE, $AUTOHEADER,
+ $AUTOPOINT, $ACLOCAL and $LIBTOOLIZE
+ Fixed problem with symbols creation in Makefile.am which was assuming that
+ all versions of ccp write to standard output by default (Martin Banky). The
+ bug was introduced in libpng-1.2.9beta5.
+ Removed unused mkinstalldirs.
+
+Version 1.5.0beta49 [October 8, 2010]
+ Undid Makefile.am revision of 1.5.0beta48.
+
+Version 1.5.0beta50 [October 14, 2010]
+ Revised Makefile.in to account for mkinstalldirs being removed.
+ Added some "(unsigned long)" typecasts in printf statements in pngvalid.c.
+ Suppressed a compiler warning in png_handle_sPLT().
+ Check for out-of-range text compression mode in png_set_text().
+
+Version 1.5.0beta51 [October 15, 2010]
+ Changed embedded dates to "(PENDING RELEASE) in beta releases (and future
+ rc releases) to minimize the difference between releases.
+
+Version 1.5.0beta52 [October 16, 2010]
+ Restored some of the embedded dates (in png.h, png.c, documentation, etc.)
+
+Version 1.5.0beta53 [October 18, 2010]
+ Updated INSTALL to mention using "make maintainer-clean" and to remove
+ obsolete statement about a custom ltmain.sh
+ Disabled "color-tests" by default in Makefile.am so it will work with
+ automake versions earlier than 1.11.1
+ Use document name "libpng-manual.txt" instead of "libpng-<version>.txt"
+ to simplify version differences.
+ Removed obsolete remarks about setjmp handling from INSTALL.
+ Revised and renamed the typedef in png.h and png.c that was designed
+ to catch library and header mismatch.
+
+Version 1.5.0beta54 [November 10, 2010]
+ Require 48 bytes, not 64 bytes, for big_row_buf in overflow checks.
+ Used a consistent structure for the pngget.c functions.
+
+Version 1.5.0beta55 [November 21, 2010]
+ Revised png_get_uint_32, png_get_int_32, png_get_uint_16 (Cosmin)
+ Moved reading of file signature into png_read_sig (Cosmin)
+ Fixed atomicity of chunk header serialization (Cosmin)
+ Added test for io_state in pngtest.c (Cosmin)
+ Added "#!/bin/sh" at the top of contrib/pngminim/*/gather.sh scripts.
+ Changes to remove gcc warnings (John Bowler)
+ Certain optional gcc warning flags resulted in warnings in libpng code.
+ With these changes only -Wconversion and -Wcast-qual cannot be turned on.
+ Changes are trivial rearrangements of code. -Wconversion is not possible
+ for pngrutil.c (because of the widespread use of += et al on variables
+ smaller than (int) or (unsigned int)) and -Wcast-qual is not possible
+ with pngwio.c and pngwutil.c because the 'write' callback and zlib
+ compression both fail to declare their input buffers with 'const'.
+
+Version 1.5.0beta56 [December 7, 2010]
+ Added the private PNG_UNUSED() macro definition in pngpriv.h.
+ Added some commentary about PNG_EXPORT in png.h and pngconf.h
+ Revised PNG_EXPORT() macro and added PNG_EXPORTA() macro, with the
+ objective of simplifying and improving the cosmetic appearance of png.h.
+ Fixed some incorrect "=" macro names in pnglibconf.dfa
+ Included documentation of changes in 1.5.0 from 1.4.x in libpng-manual.txt
+
+Version 1.5.0beta57 [December 9, 2010]
+ Documented the pngvalid gamma error summary with additional comments and
+ print statements.
+ Improved missing symbol handling in checksym.awk; symbols missing in both
+ the old and new files can now be optionally ignored, treated as errors
+ or warnings.
+ Removed references to pngvcrd.c and pnggccrd.c from the vstudio project.
+ Updated "libpng14" to "libpng15" in the visualc71 project.
+ Enabled the strip16 tests in pngvalid.`
+ Don't display test results (except PASS/FAIL) when running "make test".
+ Instead put them in pngtest-log.txt
+ Added "--with-zprefix=<string>" to configure.ac
+ Updated the prebuilt configuration files to autoconf version 2.68
+
+Version 1.5.0beta58 [December 19, 2010]
+ Fixed interlace image handling and add test cases (John Bowler)
+ Fixed the clean rule in Makefile.am to remove pngtest-log.txt
+ Made minor changes to work around warnings in gcc 3.4
+
+Version 1.5.0rc01 [December 27, 2010]
+ No changes.
+
+Version 1.5.0rc02 [December 27, 2010]
+ Eliminated references to the scripts/*.def files in project/visualc71.
+
+Version 1.5.0rc03 [December 28, 2010]
+ Eliminated scripts/*.def and revised Makefile.am accordingly
+
+Version 1.5.0rc04 [December 29, 2010]
+ Fixed bug in background transformation handling in pngrtran.c (it was
+ looking for the flag in png_ptr->transformations instead of in
+ png_ptr->flags) (David Raymond).
+
+Version 1.5.0rc05 [December 31, 2010]
+ Fixed typo in a comment in CMakeLists.txt (libpng14 => libpng15) (Cosmin)
+
+Version 1.5.0rc06 [January 4, 2011]
+ Changed the new configure option "zprefix=string" to "zlib-prefix=string"
+
+Version 1.5.0rc07 [January 4, 2011]
+ Updated copyright year.
+
+Version 1.5.0 [January 6, 2011]
+ No changes.
+
+version 1.5.1beta01 [January 8, 2011]
+ Added description of png_set_crc_action() to the manual.
+ Added a note in the manual that the type of the iCCP profile was changed
+ from png_charpp to png_bytepp in png_get_iCCP(). This change happened
+ in version 1.5.0beta36 but is not noted in the CHANGES. Similarly,
+ it was changed from png_charpp to png_const_bytepp in png_set_iCCP().
+ Ensure that png_rgb_to_gray ignores palette mapped images, if libpng
+ internally happens to call it with one, and fixed a failure to handle
+ palette mapped images correctly. This fixes CVE-2690.
+
+Version 1.5.1beta02 [January 14, 2011]
+ Fixed a bug in handling of interlaced images (bero at arklinux.org).
+ Updated CMakeLists.txt (Clifford Yapp)
+
+Version 1.5.1beta03 [January 14, 2011]
+ Fixed typecasting of some png_debug() statements (Cosmin)
+
+Version 1.5.1beta04 [January 16, 2011]
+ Updated documentation of png_set|get_tRNS() (Thomas Klausner).
+ Mentioned in the documentation that applications must #include "zlib.h"
+ if they need access to anything in zlib.h, and that a number of
+ macros such as png_memset() are no longer accessible by applications.
+ Corrected pngvalid gamma test "sample" function to access all of the color
+ samples of each pixel, instead of sampling the red channel three times.
+ Prefixed variable names index, div, exp, gamma with "png_" to avoid "shadow"
+ warnings, and (mistakenly) changed png_exp() to exp().
+
+Version 1.5.1beta05 [January 16, 2011]
+ Changed variable names png_index, png_div, png_exp, and png_gamma to
+ char_index, divisor, exp_b10, and gamma_val, respectively, and
+ changed exp() back to png_exp().
+
+Version 1.5.1beta06 [January 20, 2011]
+ Prevent png_push_crc_skip() from hanging while reading an unknown chunk
+ or an over-large compressed zTXt chunk with the progressive reader.
+ Eliminated more GCC "shadow" warnings.
+ Revised png_fixed() in png.c to avoid compiler warning about reaching the
+ end without returning anything.
+
+Version 1.5.1beta07 [January 22, 2011]
+ In the manual, describe the png_get_IHDR() arguments in the correct order.
+ Added const_png_structp and const_png_infop types, and used them in
+ prototypes for most png_get_*() functions.
+
+Version 1.5.1beta08 [January 23, 2011]
+ Added png_get_io_chunk_type() and deprecated png_get_io_chunk_name()
+ Added synopses for the IO_STATE functions and other missing synopses
+ to the manual. Removed the synopses from libpngpf.3 because they
+ were out of date and no longer useful. Better information can be
+ obtained by reading the prototypes and comments in pngpriv.h
+ Attempted to fix cpp on Solaris with S. Studio 12 cc, fix build
+ Added a make macro DFNCPP that is a CPP that will accept the tokens in
+ a .dfn file and adds configure stuff to test for such a CPP. ./configure
+ should fail if one is not available.
+ Corrected const_png_ in png.h to png_const_ to avoid polluting the namespace.
+ Added png_get_current_row_number and png_get_current_pass_number for the
+ benefit of the user transform callback.
+ Added png_process_data_pause and png_process_data_skip for the benefit of
+ progressive readers that need to stop data processing or want to optimize
+ skipping of unread data (e.g., if the reader marks a chunk to be skipped.)
+
+Version 1.5.1beta09 [January 24, 2011]
+ Enhanced pngvalid, corrected an error in gray_to_rgb, corrected doc error.
+ pngvalid contains tests of transforms, which tests are currently disabled
+ because they are incompletely tested. gray_to_rgb was failing to expand
+ the bit depth for smaller bit depth images; this seems to be a long
+ standing error and resulted, apparently, in invalid output
+ (CVE-2011-0408, CERT VU#643140). The documentation did not accurately
+ describe what libpng really does when converting RGB to gray.
+
+Version 1.5.1beta10 [January 27, 2010]
+ Fixed incorrect examples of callback prototypes in the manual, that were
+ introduced in libpng-1.0.0.
+ In addition the order of the png_get_uint macros with respect to the
+ relevant function definitions has been reversed. This helps the
+ preprocessing of the symbol files be more robust. Furthermore, the
+ symbol file preprocessing now uses -DPNG_NO_USE_READ_MACROS even when
+ the library may actually be built with PNG_USE_READ_MACROS; this stops
+ the read macros interfering with the symbol file format.
+ Made the manual, synopses, and function prototypes use the function
+ argument names file_gamma, int_file_gamma, and srgb_intent consistently.
+
+Version 1.5.1beta11 [January 28, 2011]
+ Changed PNG_UNUSED from "param=param;" to "{if(param){}}".
+ Corrected local variable type in new API png_process_data_skip()
+ The type was self-evidently incorrect but only causes problems on 64-bit
+ architectures.
+ Added transform tests to pngvalid and simplified the arguments.
+
+Version 1.5.1rc01 [January 29, 2011]
+ No changes.
+
+Version 1.5.1rc02 [January 31, 2011]
+ Added a request in the manual that applications do not use "png_" or
+ "PNG_" to begin any of their own symbols.
+ Changed PNG_UNUSED to "(void)param;" and updated the commentary in pngpriv.h
+
+Version 1.5.1 [February 3, 2011]
+ No changes.
+
+Version 1.5.2beta01 [February 13, 2011]
+ More -Wshadow fixes for older gcc compilers. Older gcc versions apparently
+ check formal parameters names in function declarations (as well as
+ definitions) to see if they match a name in the global namespace.
+ Revised PNG_EXPORTA macro to not use an empty parameter, to accommodate the
+ old VisualC++ preprocessor.
+ Turned on interlace handling in png_read_png().
+ Fixed gcc pendantic warnings.
+ Handle longjmp in Cygwin.
+ Fixed png_get_current_row_number() in the interlaced case.
+ Cleaned up ALPHA flags and transformations.
+ Implemented expansion to 16 bits.
+
+Version 1.5.2beta02 [February 19, 2011]
+ Fixed mistake in the descriptions of user read_transform and write_transform
+ function prototypes in the manual. The row_info struct is png_row_infop.
+ Reverted png_get_current_row_number() to previous (1.5.2beta01) behavior.
+ Corrected png_get_current_row_number documentation
+ Fixed the read/write row callback documentation.
+ This documents the current behavior, where the callback is called after
+ every row with information pertaining to the next row.
+
+Version 1.5.2beta03 [March 3, 2011]
+ Fixed scripts/makefile.vcwin32
+ Updated contrib/pngsuite/README to add the word "modify".
+ Define PNG_ALLOCATED to blank when _MSC_VER<1300.
+
+Version 1.5.2rc01 [March 19, 2011]
+ Define remaining attributes to blank when MSC_VER<1300.
+ ifdef out mask arrays in pngread.c when interlacing is not supported.
+
+Version 1.5.2rc02 [March 22, 2011]
+ Added a hint to try CPP=/bin/cpp if "cpp -E" fails in scripts/pnglibconf.mak
+ and in contrib/pngminim/*/makefile, eg., on SunOS 5.10, and removed "strip"
+ from the makefiles.
+ Fixed a bug (present since libpng-1.0.7) that makes png_handle_sPLT() fail
+ to compile when PNG_NO_POINTER_INDEXING is defined (Chubanov Kirill)
+
+Version 1.5.2rc03 [March 24, 2011]
+ Don't include standard header files in png.h while building the symbol table,
+ to avoid cpp failure on SunOS (introduced PNG_BUILDING_SYMBOL_TABLE macro).
+
+Version 1.5.2 [March 31, 2011]
+ No changes.
+
+Version 1.5.3beta01 [April 1, 2011]
+ Re-initialize the zlib compressor before compressing non-IDAT chunks.
+ Added API functions (png_set_text_compression_level() and four others) to
+ set parameters for zlib compression of non-IDAT chunks.
+
+Version 1.5.3beta02 [April 3, 2011]
+ Updated scripts/symbols.def with new API functions.
+ Only compile the new zlib re-initializing code when text or iCCP is
+ supported, using PNG_WRITE_COMPRESSED_TEXT_SUPPORTED macro.
+ Improved the optimization of the zlib CMF byte (see libpng-1.2.6beta03).
+ Optimize the zlib CMF byte in non-IDAT compressed chunks
+
+Version 1.5.3beta03 [April 16, 2011]
+ Fixed gcc -ansi -pedantic compile. A strict ANSI system does not have
+ snprintf, and the "__STRICT_ANSI__" detects that condition more reliably
+ than __STDC__ (John Bowler).
+ Removed the PNG_PTR_NORETURN attribute because it too dangerous. It tells
+ the compiler that a user supplied callback (the error handler) does not
+ return, yet there is no guarantee in practice that the application code
+ will correctly implement the error handler because the compiler only
+ issues a warning if there is a mistake (John Bowler).
+ Removed the no-longer-used PNG_DEPSTRUCT macro.
+ Updated the zlib version to 1.2.5 in the VStudio project.
+ Fixed 64-bit builds where png_uint_32 is smaller than png_size_t in
+ pngwutil.c (John Bowler).
+ Fixed bug with stripping the filler or alpha channel when writing, that
+ was introduced in libpng-1.5.2beta01 (bug report by Andrew Church).
+
+Version 1.5.3beta04 [April 27, 2011]
+ Updated pngtest.png with the new zlib CMF optimization.
+ Cleaned up conditional compilation code and of background/gamma handling
+ Internal changes only except a new option to avoid compiling the
+ png_build_grayscale_palette API (which is not used at all internally.)
+ The main change is to move the transform tests (READ_TRANSFORMS,
+ WRITE_TRANSFORMS) up one level to the caller of the APIs. This avoids
+ calls to spurious functions if all transforms are disabled and slightly
+ simplifies those functions. Pngvalid modified to handle this.
+ A minor change is to stop the strip_16 and expand_16 interfaces from
+ disabling each other; this allows the future alpha premultiplication
+ code to use 16-bit intermediate values while still producing 8-bit output.
+ png_do_background and png_do_gamma have been simplified to take a single
+ pointer to the png_struct rather than pointers to every item required
+ from the png_struct. This makes no practical difference to the internal
+ code.
+ A serious bug in the pngvalid internal routine 'standard_display_init' has
+ been fixed - this failed to initialize the red channel and accidentally
+ initialized the alpha channel twice.
+ Changed png_struct jmp_buf member name from png_jmpbuf to tmp_jmpbuf to
+ avoid a possible clash with the png_jmpbuf macro on some platforms.
+
+Version 1.5.3beta05 [May 6, 2011]
+ Added the "_POSIX_SOURCE" feature test macro to ensure libpng sees the
+ correct API. _POSIX_SOURCE is defined in pngpriv.h, pngtest.c and
+ pngvalid.c to ensure that POSIX conformant systems disable non-POSIX APIs.
+ Removed png_snprintf and added formatted warning messages. This change adds
+ internal APIs to allow png_warning messages to have parameters without
+ requiring the host OS to implement snprintf. As a side effect the
+ dependency of the tIME-supporting RFC1132 code on stdio is removed and
+ PNG_NO_WARNINGS does actually work now.
+ Pass "" instead of '\0' to png_default_error() in png_err(). This mistake
+ was introduced in libpng-1.2.20beta01. This fixes CVE-2011-2691.
+ Added PNG_WRITE_OPTIMIZE_CMF_SUPPORTED macro to make the zlib "CMF" byte
+ optimization configureable.
+ IDAT compression failed if preceded by a compressed text chunk (bug
+ introduced in libpng-1.5.3beta01-02). This was because the attempt to
+ reset the zlib stream in png_write_IDAT happened after the first IDAT
+ chunk had been deflated - much too late. In this change internal
+ functions were added to claim/release the z_stream and, hopefully, make
+ the code more robust. Also deflateEnd checking is added - previously
+ libpng would ignore an error at the end of the stream.
+
+Version 1.5.3beta06 [May 8, 2011]
+ Removed the -D_ALL_SOURCE from definitions for AIX in CMakeLists.txt
+ Implemented premultiplied alpha support: png_set_alpha_mode API
+
+Version 1.5.3beta07 [May 11, 2011]
+ Added expand_16 support to the high level interface.
+ Added named value and 'flag' gamma support to png_set_gamma. Made a minor
+ change from the previous (unreleased) ABI/API to hide the exact value used
+ for Macs - it's not a good idea to embed this in the ABI!
+ Moved macro definitions for PNG_HAVE_IHDR, PNG_HAVE_PLTE, and PNG_AFTER_IDAT
+ from pngpriv.h to png.h because they must be visible to applications
+ that call png_set_unknown_chunks().
+ Check for up->location !PNG_AFTER_IDAT when writing unknown chunks
+ before IDAT.
+
+Version 1.5.3beta08 [May 16, 2011]
+ Improved "pngvalid --speed" to exclude more of pngvalid from the time.
+ Documented png_set_alpha_mode(), other changes in libpng.3/libpng-manual.txt
+ The cHRM chunk now sets the defaults for png_set_rgb_to_gray() (when negative
+ parameters are supplied by the caller), while in the absence of cHRM
+ sRGB/Rec 709 values are still used. This introduced a divide-by-zero
+ bug in png_handle_cHRM().
+ The bKGD chunk no longer overwrites the background value set by
+ png_set_background(), allowing the latter to be used before the file
+ header is read. It never performed any useful function to override
+ the default anyway.
+ Added memory overwrite and palette image checks to pngvalid.c
+ Previously palette image code was poorly checked. Since the transformation
+ code has a special palette path in most cases this was a severe weakness.
+ Minor cleanup and some extra checking in pngrutil.c and pngrtran.c. When
+ expanding an indexed image, always expand to RGBA if transparency is
+ present.
+
+Version 1.5.3beta09 [May 17, 2011]
+ Reversed earlier 1.5.3 change of transformation order; move png_expand_16
+ back where it was. The change doesn't work because it requires 16-bit
+ gamma tables when the code only generates 8-bit ones. This fails
+ silently; the libpng code just doesn't do any gamma correction. Moving
+ the tests back leaves the old, inaccurate, 8-bit gamma calculations, but
+ these are clearly better than none!
+
+Version 1.5.3beta10 [May 20, 2011]
+
+ png_set_background() and png_expand_16() did not work together correctly.
+ This problem is present in 1.5.2; if png_set_background is called with
+ need_expand false and the matching 16 bit color libpng erroneously just
+ treats it as an 8-bit color because of where png_do_expand_16 is in the
+ transform list. This simple fix reduces the supplied colour to 8-bits,
+ so it gets smashed, but this is better than the current behavior.
+ Added tests for expand16, more fixes for palette image tests to pngvalid.
+ Corrects the code for palette image tests and disables attempts to
+ validate palette colors.
+
+Version 1.5.3rc01 [June 3, 2011]
+ No changes.
+
+Version 1.5.3rc02 [June 8, 2011]
+ Fixed uninitialized memory read in png_format_buffer() (Bug report by
+ Frank Busse, CVE-2011-2501, related to CVE-2004-0421).
+
+Version 1.5.3beta11 [June 11, 2011]
+ Fixed png_handle_sCAL which is broken in 1.5. This fixes CVE 2011-2692.
+ Added sCAL to pngtest.png
+ Revised documentation about png_set_user_limits() to say that it also affects
+ png writing.
+ Revised handling of png_set_user_limits() so that it can increase the
+ limit beyond the PNG_USER_WIDTH|HEIGHT_MAX; previously it could only
+ reduce it.
+ Make the 16-to-8 scaling accurate. Dividing by 256 with no rounding is
+ wrong (high by one) 25% of the time. Dividing by 257 with rounding is
+ wrong in 128 out of 65536 cases. Getting the right answer all the time
+ without division is easy.
+ Added "_SUPPORTED" to the PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION macro.
+ Added projects/owatcom, an IDE project for OpenWatcom to replace
+ scripts/makefile.watcom. This project works with OpenWatcom 1.9. The
+ IDE autogenerates appropriate makefiles (libpng.mk) for batch processing.
+ The project is configurable, unlike the Visual Studio project, so long
+ as the developer has an awk.
+ Changed png_set_gAMA to limit the gamma value range so that the inverse
+ of the stored value cannot overflow the fixed point representation,
+ and changed other things OpenWatcom warns about.
+ Revised pngvalid.c to test PNG_ALPHA_MODE_SUPPORTED correctly. This allows
+ pngvalid to build when ALPHA_MODE is not supported, which is required if
+ it is to build on libpng 1.4.
+ Removed string/memory macros that are no longer used and are not
+ necessarily fully supportable, particularly png_strncpy and png_snprintf.
+ Added log option to pngvalid.c and attempted to improve gamma messages.
+
+Version 1.5.3 [omitted]
+ People found the presence of a beta release following an rc release
+ to be confusing; therefore we bump the version to libpng-1.5.4beta01
+ and there will be no libpng-1.5.3 release.
+
+Version 1.5.4beta01 [June 14, 2011]
+ Made it possible to undefine PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
+ to get the same (inaccurate) output as libpng-1.5.2 and earlier.
+ Moved definitions of PNG_HAVE_IHDR, PNG_AFTER_IDAT, and PNG_HAVE_PLTE
+ outside of an unknown-chunk block in png.h because they are also
+ needed for other uses.
+
+Version 1.5.4beta02 [June 14, 2011]
+ Fixed and clarified LEGACY 16-to-8 scaling code.
+ Added png_set_chop_16() API, to match inaccurate results from previous
+ libpng versions.
+ Removed the ACCURATE and LEGACY options (they are no longer useable)
+ Use the old scaling method for background if png_set_chop_16() was
+ called.
+ Made png_set_chop_16() API removeable by disabling PNG_CHOP_16_TO_8_SUPPORTED
+
+Version 1.5.4beta03 [June 15, 2011]
+ Fixed a problem in png_do_expand_palette() exposed by optimization in
+ 1.5.3beta06
+ Also removed a spurious and confusing "trans" member ("trans") from png_info.
+ The palette expand optimization prevented expansion to an intermediate RGBA
+ form if tRNS was present but alpha was marked to be stripped; this exposed
+ a check for tRNS in png_do_expand_palette() which is inconsistent with the
+ code elsewhere in libpng.
+ Correction to the expand_16 code; removed extra instance of
+ png_set_scale_16_to_8 from pngpriv.h
+
+Version 1.5.4beta04 [June 16, 2011]
+ Added a missing "#ifdef PNG_READ_BACKGROUND_SUPPORTED/#endif" in pngrtran.c
+ Added PNG_TRANSFORM_CHOP_16 to the high-level read transforms.
+ Made PNG_READ_16_TO_8_ACCURATE_SCALE configurable again. If this is
+ not enabled, png_set_strip_16() and png_do_scale_16_to_8() aren't built.
+ Revised contrib/visupng, gregbook, and pngminim to demonstrate chop_16_to_8
+
+Version 1.5.4beta05 [June 16, 2011]
+ Renamed png_set_strip_16() to png_set_scale_16() and renamed
+ png_set_chop_16() to png_set_strip(16) in an attempt to minimize the
+ behavior changes between libpng14 and libpng15.
+
+Version 1.5.4beta06 [June 18, 2011]
+ Fixed new bug that was causing both strip_16 and scale_16 to be applied.
+
+Version 1.5.4beta07 [June 19, 2011]
+ Fixed pngvalid, simplified macros, added checking for 0 in sCAL.
+ The ACCURATE scale macro is no longer defined in 1.5 - call the
+ png_scale_16_to_8 API. Made sure that PNG_READ_16_TO_8 is still defined
+ if the png_strip_16_to_8 API is present. png_check_fp_number now
+ maintains some state so that positive, negative and zero values are
+ identified. sCAL uses these to be strictly spec conformant.
+
+Version 1.5.4beta08 [June 23, 2011]
+ Fixed pngvalid if ACCURATE_SCALE is defined.
+ Updated scripts/pnglibconf.h.prebuilt.
+
+Version 1.5.4rc01 [June 30, 2011]
+ Define PNG_ALLOCATED to "restrict" only if MSC_VER >= 1400.
+
+Version 1.5.4 [July 7, 2011]
+ No changes.
+
+Version 1.5.5beta01 [July 13, 2011]
+ Fixed some typos and made other minor changes in the manual.
+ Updated contrib/pngminus/makefile.std (Samuli Souminen)
+
+Version 1.5.5beta02 [July 14, 2011]
+ Revised Makefile.am and Makefile.in to look in the right directory for
+ pnglibconf.h.prebuilt
+
+Version 1.5.5beta03 [July 27, 2011]
+ Enabled compilation with g++ compiler. This compiler does not recognize
+ the file extension, so it always compiles with C++ rules. Made minor
+ changes to pngrutil.c to cast results where C++ expects it but C does not.
+ Minor editing of libpng.3 and libpng-manual.txt.
+
+Version 1.5.5beta04 [July 29, 2011]
+ Revised CMakeLists.txt (Clifford Yapp)
+ Updated commentary about the png_rgb_to_gray() default coefficients
+ in the manual and in pngrtran.c
+
+Version 1.5.5beta05 [August 17, 2011]
+ Prevent unexpected API exports from non-libpng DLLs on Windows. The "_DLL"
+ is removed from the test of whether a DLL is being built (this erroneously
+ caused the libpng APIs to be marked as DLL exports in static builds under
+ Microsoft Visual Studio). Almost all of the libpng building configuration
+ is moved from pngconf.h to pngpriv.h, but PNG_DLL_EXPORT remains in
+ pngconf.h, though, so that it is colocated with the import definition (it
+ is no longer used anywhere in the installed headers). The VStudio project
+ definitions have been cleaned up: "_USRDLL" has been removed from the
+ static library builds (this was incorrect), and PNG_USE_DLL has been added
+ to pngvalid to test the functionality (pngtest does not supply it,
+ deliberately). The spurious "_EXPORTS" has been removed from the
+ libpng build (all these errors were a result of copy/paste between project
+ configurations.)
+ Added new types and internal functions for CIE RGB end point handling to
+ pngpriv.h (functions yet to be implemented).
+
+Version 1.5.5beta06 [August 26, 2011]
+ Ensure the CMAKE_LIBRARY_OUTPUT_DIRECTORY is set in CMakeLists.txt
+ (Clifford Yap)
+ Fixes to rgb_to_gray and cHRM XYZ APIs (John Bowler):
+ The rgb_to_gray code had errors when combined with gamma correction.
+ Some pixels were treated as true grey when they weren't and such pixels
+ and true grey ones were not gamma corrected (the original value of the
+ red component was used instead). APIs to get and set cHRM using color
+ space end points have been added and the rgb_to_gray code that defaults
+ based on cHRM, and the divide-by-zero bug in png_handle_cHRM (CERT
+ VU#477046, CVE-2011-3328, introduced in 1.5.4) have been corrected.
+ A considerable number of tests has been added to pngvalid for the
+ rgb_to_gray transform.
+ Arithmetic errors in rgb_to_gray whereby the calculated gray value was
+ truncated to the bit depth rather than rounded have been fixed except in
+ the 8-bit non-gamma-corrected case (where consistency seems more important
+ than correctness.) The code still has considerable inaccuracies in the
+ 8-bit case because 8-bit linear arithmetic is used.
+
+Version 1.5.5beta07 [September 7, 2011]
+ Added "$(ARCH)" option to makefile.darwin
+ Added SunOS support to configure.ac and Makefile.am
+ Changed png_chunk_benign_error() to png_warning() in png.c, in
+ png_XYZ_from_xy_checked().
+
+Version 1.5.5beta08 [September 10, 2011]
+ Fixed 64-bit compilation errors (gcc). The errors fixed relate
+ to conditions where types that are 32 bits in the GCC 32-bit
+ world (uLong and png_size_t) become 64 bits in the 64-bit
+ world. This produces potential truncation errors which the
+ compiler correctly flags.
+ Relocated new HAVE_SOLARIS_LD definition in configure.ac
+ Constant changes for 64-bit compatibility (removal of L suffixes). The
+ 16-bit cases still use "L" as we don't have a 16-bit test system.
+
+Version 1.5.5rc01 [September 15, 2011]
+ Removed "L" suffixes in pngpriv.h
+
+Version 1.5.5 [September 22, 2011]
+ No changes.
+
+Version 1.5.6beta01 [September 22, 2011]
+ Fixed some 64-bit type conversion warnings in pngrtran.c
+ Moved row_info from png_struct to a local variable.
+ The various interlace mask arrays have been made into arrays of
+ bytes and made PNG_CONST and static (previously some arrays were
+ marked PNG_CONST and some weren't).
+ Additional checks have been added to the transform code to validate the
+ pixel depths after the transforms on both read and write.
+ Removed some redundant code from pngwrite.c, in png_destroy_write_struct().
+ Changed chunk reading/writing code to use png_uint_32 instead of png_byte[4].
+ This removes the need to allocate temporary strings for chunk names on
+ the stack in the read/write code. Unknown chunk handling still uses the
+ string form because this is exposed in the API.
+
+Version 1.5.6beta02 [September 26, 2011]
+ Added a note in the manual the png_read_update_info() must be called only
+ once with a particular info_ptr.
+ Fixed a typo in the definition of the new PNG_STRING_FROM_CHUNK(s,c) macro.
+
+Version 1.5.6beta03 [September 28, 2011]
+ Revised test-pngtest.sh to report FAIL when pngtest fails.
+ Added "--strict" option to pngtest, to report FAIL when the failure is
+ only because the resulting valid files are different.
+ Revised CMakeLists.txt to work with mingw and removed some material from
+ CMakeLists.txt that is no longer useful in libpng-1.5.
+
+Version 1.5.6beta04 [October 5, 2011]
+ Fixed typo in Makefile.in and Makefile.am ("-M Wl" should be "-M -Wl")."
+
+Version 1.5.6beta05 [October 12, 2011]
+ Speed up png_combine_row() for interlaced images. This reduces the generality
+ of the code, allowing it to be optimized for Adam7 interlace. The masks
+ passed to png_combine_row() are now generated internally, avoiding
+ some code duplication and localizing the interlace handling somewhat.
+ Align png_struct::row_buf - previously it was always unaligned, caused by
+ a bug in the code that attempted to align it; the code needs to subtract
+ one from the pointer to take account of the filter byte prepended to
+ each row.
+ Optimized png_combine_row() when rows are aligned. This gains a small
+ percentage for 16-bit and 32-bit pixels in the typical case where the
+ output row buffers are appropriately aligned. The optimization was not
+ previously possible because the png_struct buffer was always misaligned.
+ Fixed bug in png_write_chunk_header() debug print, introduced in 1.5.6beta01.
+
+Version 1.5.6beta06 [October 17, 2011]
+ Removed two redundant tests for unitialized row.
+ Fixed a relatively harmless memory overwrite in compressed text writing
+ with a 1 byte zlib buffer.
+ Add ability to call png_read_update_info multiple times to pngvalid.c.
+ Fixes for multiple calls to png_read_update_info. These fixes attend to
+ most of the errors revealed in pngvalid, however doing the gamma work
+ twice results in inaccuracies that can't be easily fixed. There is now
+ a warning in the code if this is going to happen.
+ Turned on multiple png_read_update_info in pngvalid transform tests.
+ Prevent libpng from overwriting unused bits at the end of the image when
+ it is not byte aligned, while reading. Prior to libpng-1.5.6 libpng would
+ overwrite the partial byte at the end of each row if the row width was not
+ an exact multiple of 8 bits and the image is not interlaced.
+
+Version 1.5.6beta07 [October 21, 2011]
+ Made png_ptr->prev_row an aligned pointer into png_ptr->big_prev_row
+ (Mans Rullgard).
+
+Version 1.5.6rc01 [October 26, 2011]
+ Changed misleading "Missing PLTE before cHRM" warning to "Out of place cHRM"
+
+Version 1.5.6rc02 [October 27, 2011]
+ Added LSR() macro to defend against buggy compilers that evaluate non-taken
+ code branches and complain about out-of-range shifts.
+
+Version 1.5.6rc03 [October 28, 2011]
+ Renamed the LSR() macro to PNG_LSR() and added PNG_LSL() macro.
+ Fixed compiler warnings with Intel and MSYS compilers. The logical shift
+ fix for Microsoft Visual C is required by other compilers, so this
+ enables that fix for all compilers when using compile-time constants.
+ Under MSYS 'byte' is a name declared in a system header file, so we
+ changed the name of a local variable to avoid the warnings that result.
+ Added #define PNG_ALIGN_TYPE PNG_ALIGN_NONE to contrib/pngminim/*/pngusr.h
+
+Version 1.5.6 [November 3, 2011]
+ No changes.
+
+Version 1.5.7beta01 [November 4, 2011]
+ Added support for ARM processor, when decoding all PNG up-filtered rows
+ and any other-filtered rows with 3 or 4 bytes per pixel (Mans Rullgard).
+ Fixed bug in pngvalid on early allocation failure; fixed type cast in
+ pngmem.c; pngvalid would attempt to call png_error() if the allocation
+ of a png_struct or png_info failed. This would probably have led to a
+ crash. The pngmem.c implementation of png_malloc() included a cast
+ to png_size_t which would fail on large allocations on 16-bit systems.
+ Fix for the preprocessor of the Intel C compiler. The preprocessor
+ splits adjacent @ signs with a space; this changes the concatentation
+ token from @-@-@ to PNG_JOIN; that should work with all compiler
+ preprocessors.
+ Paeth filter speed improvements from work by Siarhei Siamashka. This
+ changes the 'Paeth' reconstruction function to improve the GCC code
+ generation on x86. The changes are only part of the suggested ones;
+ just the changes that definitely improve speed and remain simple.
+ The changes also slightly increase the clarity of the code.
+
+Version 1.5.7beta02 [November 11, 2011]
+ Check compression_type parameter in png_get_iCCP and remove spurious
+ casts. The compression_type parameter is always assigned to, so must
+ be non-NULL. The cast of the profile length potentially truncated the
+ value unnecessarily on a 16-bit int system, so the cast of the (byte)
+ compression type to (int) is specified by ANSI-C anyway.
+ Fixed FP division by zero in pngvalid.c; the 'test_pixel' code left
+ the sBIT fields in the test pixel as 0, which resulted in a floating
+ point division by zero which was irrelevant but causes systems where
+ FP exceptions cause a crash. Added code to pngvalid to turn on FP
+ exceptions if the appropriate glibc support is there to ensure this is
+ tested in the future.
+ Updated scripts/pnglibconf.mak and scripts/makefile.std to handle the
+ new PNG_JOIN macro.
+ Added versioning to pnglibconf.h comments.
+ Simplified read/write API initial version; basic read/write tested on
+ a variety of images, limited documentation (in the header file.)
+ Installed more accurate linear to sRGB conversion tables. The slightly
+ modified tables reduce the number of 16-bit values that
+ convert to an off-by-one 8-bit value. The "makesRGB.c" code that was used
+ to generate the tables is now in a contrib/sRGBtables sub-directory.
+
+Version 1.5.7beta03 [November 17, 2011]
+ Removed PNG_CONST from the sRGB table declarations in pngpriv.h and png.c
+ Added run-time detection of NEON support.
+ Added contrib/libtests; includes simplified API test and timing test and
+ a color conversion utility for rapid checking of failed 'pngstest' results.
+ Multiple transform bug fixes plus a work-round for double gamma correction.
+ libpng does not support more than one transform that requires linear data
+ at once - if this is tried typically the results is double gamma
+ correction. Since the simplified APIs can need rgb to gray combined with
+ a compose operation it is necessary to do one of these outside the main
+ libpng transform code. This check-in also contains fixes to various bugs
+ in the simplified APIs themselves and to some bugs in compose and rgb to
+ gray (on palette) itself.
+ Fixes for C++ compilation using g++ When libpng source is compiled
+ using g++. The compiler imposes C++ rules on the C source; thus it
+ is desireable to make the source work with either C or C++ rules
+ without throwing away useful error information. This change adds
+ png_voidcast to allow C semantic (void*) cases or the corresponding
+ C++ static_cast operation, as appropriate.
+ Added --noexecstack to assembler file compilation. GCC does not set
+ this on assembler compilation, even though it does on C compilation.
+ This creates security issues if assembler code is enabled; the
+ work-around is to set it by default in the flags for $(CCAS)
+ Work around compilers that don't support declaration of const data. Some
+ compilers fault 'extern const' data declarations (because the data is
+ not initialized); this turns on const-ness only for compilers where
+ this is known to work.
+
+Version 1.5.7beta04 [November 17, 2011]
+ Since the gcc driver does not recognize the --noexecstack flag, we must
+ use the -Wa prefix to have it passed through to the assembler.
+ Also removed a duplicate setting of this flag.
+ Added files that were omitted from the libpng-1.5.7beta03 zip distribution.
+
+Version 1.5.7beta05 [November 25, 2011]
+ Removed "zTXt" from warning in generic chunk decompression function.
+ Validate time settings passed to png_set_tIME() and png_convert_to_rfc1123()
+ (Frank Busse). Note: This prevented CVE-2015-7981 from affecting
+ libpng-1.5.7 and later.
+ Added MINGW support to CMakeLists.txt
+ Reject invalid compression flag or method when reading the iTXt chunk.
+ Backed out 'simplified' API changes. The API seems too complex and there
+ is a lack of consensus or enthusiasm for the proposals. The API also
+ reveals significant bugs inside libpng (double gamma correction and the
+ known bug of being unable to retrieve a corrected palette). It seems
+ better to wait until the bugs, at least, are corrected.
+ Moved pngvalid.c into contrib/libtests
+ Rebuilt Makefile.in, configure, etc., with autoconf-2.68
+
+Version 1.5.7rc01 [December 1, 2011]
+ Replaced an "#if" with "#ifdef" in pngrtran.c
+ Revised #if PNG_DO_BC block in png.c (use #ifdef and add #else)
+
+Version 1.5.7rc02 [December 5, 2011]
+ Revised project files and contrib/pngvalid/pngvalid.c to account for
+ the relocation of pngvalid into contrib/libtests.
+ Revised pngconf.h to use " __declspec(restrict)" only when MSC_VER >= 1400,
+ as in libpng-1.5.4.
+ Put CRLF line endings in the owatcom project files.
+
+Version 1.5.7rc03 [December 7, 2011]
+ Updated CMakeLists.txt to account for the relocation of pngvalid.c
+
+Version 1.5.7 [December 15, 2011]
+ Minor fixes to pngvalid.c for gcc 4.6.2 compatibility to remove warnings
+ reported by earlier versions.
+ Fixed minor memset/sizeof errors in pngvalid.c.
+
+Version 1.6.0beta01 [December 15, 2011]
+ Removed machine-generated configure files from the GIT repository (they will
+ continue to appear in the tarball distributions and in the libpng15 and
+ earlier GIT branches).
+ Restored the new 'simplified' API, which was started in libpng-1.5.7beta02
+ but later deleted from libpng-1.5.7beta05.
+ Added example programs for the new 'simplified' API.
+ Added ANSI-C (C90) headers and require them, and take advantage of the
+ change. Also fixed some of the projects/* and contrib/* files that needed
+ updates for libpng16 and the move of pngvalid.c.
+ With this change the required ANSI-C header files are assumed to exist: the
+ implementation must provide float.h, limits.h, stdarg.h and stddef.h and
+ libpng relies on limits.h and stddef.h existing and behaving as defined
+ (the other two required headers aren't used). Non-ANSI systems that don't
+ have stddef.h or limits.h will have to provide an appropriate fake
+ containing the relevant types and #defines.
+ Dropped support for 16-bit platforms. The use of FAR/far has been eliminated
+ and the definition of png_alloc_size_t is now controlled by a flag so
+ that 'small size_t' systems can select it if necessary. Libpng 1.6 may
+ not currently work on such systems -- it seems likely that it will
+ ask 'malloc' for more than 65535 bytes with any image that has a
+ sufficiently large row size (rather than simply failing to read such
+ images).
+ New tools directory containing tools used to generate libpng code.
+ Fixed race conditions in parallel make builds. With higher degrees of
+ parallelism during 'make' the use of the same temporary file names such
+ as 'dfn*' can result in a race where a temporary file from one arm of the
+ build is deleted or overwritten in another arm. This changes the
+ temporary files for suffix rules to always use $* and ensures that the
+ non-suffix rules use unique file names.
+
+Version 1.6.0beta02 [December 21, 2011]
+ Correct configure builds where build and source directories are separate.
+ The include path of 'config.h' was erroneously made relative in pngvalid.c
+ in libpng 1.5.7.
+
+Version 1.6.0beta03 [December 22, 2011]
+ Start-up code size improvements, error handler flexibility. These changes
+ alter how the tricky allocation of the initial png_struct and png_info
+ structures are handled. png_info is now handled in pretty much the same
+ way as everything else, except that the allocations handle NULL return
+ silently. png_struct is changed in a similar way on allocation and on
+ deallocation a 'safety' error handler is put in place (which should never
+ be required). The error handler itself is changed to permit mismatches
+ in the application and libpng error buffer size; however, this means a
+ silent change to the API to return the jmp_buf if the size doesn't match
+ the size from the libpng compilation; libpng now allocates the memory and
+ this may fail. Overall these changes result in slight code size
+ reductions; however, this is a reduction in code that is always executed
+ so is particularly valuable. Overall on a 64-bit system the libpng DLL
+ decreases in code size by 1733 bytes. pngerror.o increases in size by
+ about 465 bytes because of the new functionality.
+ Added png_convert_to_rfc1123_buffer() and deprecated png_convert_to_rfc1123()
+ to avoid including a spurious buffer in the png_struct.
+
+Version 1.6.0beta04 [December 30, 2011]
+ Regenerated configure scripts with automake-1.11.2
+ Eliminated png_info_destroy(). It is now used only in png.c and only calls
+ one other internal function and memset().
+ Enabled png_get_sCAL_fixed() if floating point APIs are enabled. Previously
+ it was disabled whenever internal fixed point arithmetic was selected,
+ which meant it didn't exist even on systems where FP was available but not
+ preferred.
+ Added pngvalid.c compile time checks for const APIs.
+ Implemented 'restrict' for png_info and png_struct. Because of the way
+ libpng works both png_info and png_struct are always accessed via a
+ single pointer. This means adding C99 'restrict' to the pointer gives
+ the compiler some opportunity to optimize the code. This change allows
+ that.
+ Moved AC_MSG_CHECKING([if libraries can be versioned]) later to the proper
+ location in configure.ac (Gilles Espinasse).
+ Changed png_memcpy to C assignment where appropriate. Changed all those
+ uses of png_memcpy that were doing a simple assignment to assignments
+ (all those cases where the thing being copied is a non-array C L-value).
+ Added some error checking to png_set_*() routines.
+ Removed the reference to the non-exported function png_memcpy() from
+ example.c.
+ Fixed the Visual C 64-bit build - it requires jmp_buf to be aligned, but
+ it had become misaligned.
+ Revised contrib/pngminus/pnm2png.c to avoid warnings when png_uint_32
+ and unsigned long are of different sizes.
+
+Version 1.6.0beta05 [January 15, 2012]
+ Updated manual with description of the simplified API (copied from png.h)
+ Fix bug in pngerror.c: some long warnings were being improperly truncated
+ (CVE-2011-3464, bug introduced in libpng-1.5.3beta05).
+
+Version 1.6.0beta06 [January 24, 2012]
+ Added palette support to the simplified APIs. This commit
+ changes some of the macro definitions in png.h, app code
+ may need corresponding changes.
+ Increased the formatted warning buffer to 192 bytes.
+ Added color-map support to simplified API. This is an initial version for
+ review; the documentation has not yet been updated.
+ Fixed Min/GW uninstall to remove libpng.dll.a
+
+Version 1.6.0beta07 [January 28, 2012]
+ Eliminated Intel icc/icl compiler warnings. The Intel (GCC derived)
+ compiler issues slightly different warnings from those issued by the
+ current vesions of GCC. This eliminates those warnings by
+ adding/removing casts and small code rewrites.
+ Updated configure.ac from autoupdate: added --enable-werror option.
+ Also some layout regularization and removal of introduced tab characters
+ (replaced with 3-character indentation). Obsolete macros identified by
+ autoupdate have been removed; the replacements are all in 2.59 so
+ the pre-req hasn't been changed. --enable-werror checks for support
+ for -Werror (or the given argument) in the compiler. This mimics the
+ gcc configure option by allowing -Werror to be turned on safely; without
+ the option the tests written in configure itself fail compilation because
+ they cause compiler warnings.
+ Rewrote autogen.sh to run autoreconf instead of running tools one-by-one.
+ Conditionalize the install rules for MINGW and CYGWIN in CMakeLists.txt and
+ set CMAKE_LIBRARY_OUTPUT_DIRECTORY to "lib" on all platforms (C. Yapp).
+ Freeze libtool files in the 'scripts' directory. This version of autogen.sh
+ attempts to dissuade people from running it when it is not, or should not,
+ be necessary. In fact, autogen.sh does not work when run in a libpng
+ directory extracted from a tar distribution anymore. You must run it in
+ a GIT clone instead.
+ Added two images to contrib/pngsuite (1-bit and 2-bit transparent grayscale),
+ and renamed three whose names were inconsistent with those in
+ pngsuite/README.txt.
+
+Version 1.6.0beta08 [February 1, 2012]
+ Fixed Image::colormap misalignment in pngstest.c
+ Check libtool/libtoolize version number (2.4.2) in configure.ac
+ Divide test-pngstest.sh into separate pngstest runs for basic and
+ transparent images.
+ Moved automake options to AM_INIT_AUTOMAKE in configure.ac
+ Added color-tests, silent-rules (Not yet implemented in Makefile.am) and
+ version checking to configure.ac
+ Improved pngstest speed by not doing redundant tests and add const to
+ the background parameter of png_image_finish_read. The --background
+ option is now done automagically only when required, so that commandline
+ option no longer exists.
+ Cleaned up pngpriv.h to consistently declare all functions and data.
+ Also eliminated PNG_CONST_DATA, which is apparently not needed but we
+ can't be sure until it is gone.
+ Added symbol prefixing that allows all the libpng external symbols
+ to be prefixed (suggested by Reuben Hawkins).
+ Updated "ftbb*.png" list in the owatcom and vstudio projects.
+ Fixed 'prefix' builds on clean systems. The generation of pngprefix.h
+ should not require itself.
+ Updated INSTALL to explain that autogen.sh must be run in a GIT clone,
+ not in a libpng directory extracted from a tar distribution.
+
+Version 1.6.0beta09 [February 1, 2012]
+ Reverted the prebuilt configure files to libpng-1.6.0beta05 condition.
+
+Version 1.6.0beta10 [February 3, 2012]
+ Added Z_SOLO for zlib-1.2.6+ and correct pngstest tests
+ Updated list of test images in CMakeLists.txt
+ Updated the prebuilt configure files to current condition.
+ Revised INSTALL information about autogen.sh; it works in tar distributions.
+
+Version 1.6.0beta11 [February 16, 2012]
+ Fix character count in pngstest command in projects/owatcom/pngstest.tgt
+ Revised test-pngstest.sh to report PASS/FAIL for each image.
+ Updated documentation about the simplified API.
+ Corrected estimate of error in libpng png_set_rgb_to_gray API. The API is
+ extremely inaccurate for sRGB conversions because it uses an 8-bit
+ intermediate linear value and it does not use the sRGB transform, so it
+ suffers from the known instability in gamma transforms for values close
+ to 0 (see Poynton). The net result is that the calculation has a maximum
+ error of 14.99/255; 0.5/255^(1/2.2). pngstest now uses 15 for the
+ permitted 8-bit error. This may still not be enough because of arithmetic
+ error.
+ Removed some unused arrays (with #ifdef) from png_read_push_finish_row().
+ Fixed a memory overwrite bug in simplified read of RGB PNG with
+ non-linear gamma Also bugs in the error checking in pngread.c and changed
+ quite a lot of the checks in pngstest.c to be correct; either correctly
+ written or not over-optimistic. The pngstest changes are insufficient to
+ allow all possible RGB transforms to be passed; pngstest cmppixel needs
+ to be rewritten to make it clearer which errors it allows and then changed
+ to permit known inaccuracies.
+ Removed tests for no-longer-used *_EMPTY_PLTE_SUPPORTED from pngstruct.h
+ Fixed fixed/float API export conditionals. 1) If FIXED_POINT or
+ FLOATING_POINT options were switched off, png.h ended up with lone ';'
+ characters. This is not valid ANSI-C outside a function. The ';'
+ characters have been moved inside the definition of PNG_FP_EXPORT and
+ PNG_FIXED_EXPORT. 2) If either option was switched off, the declaration
+ of the corresponding functions were completely omitted, even though some
+ of them are still used internally. The result is still valid, but
+ produces warnings from gcc with some warning options (including -Wall). The
+ fix is to cause png.h to declare the functions with PNG_INTERNAL_FUNCTION
+ when png.h is included from pngpriv.h.
+ Check for invalid palette index while reading paletted PNG. When one is
+ found, issue a warning and increase png_ptr->num_palette accordingly.
+ Apps are responsible for checking to see if that happened.
+
+Version 1.6.0beta12 [February 18, 2012]
+ Do not increase num_palette on invalid_index.
+ Relocated check for invalid palette index to pngrtran.c, after unpacking
+ the sub-8-bit pixels.
+ Fixed CVE-2011-3026 buffer overrun bug. This bug was introduced when
+ iCCP chunk support was added at libpng-1.0.6. Deal more correctly with the
+ test on iCCP chunk length. Also removed spurious casts that may hide
+ problems on 16-bit systems.
+
+Version 1.6.0beta13 [February 24, 2012]
+ Eliminated redundant png_push_read_tEXt|zTXt|iTXt|unknown code from
+ pngpread.c and use the sequential png_handle_tEXt, etc., in pngrutil.c;
+ now that png_ptr->buffer is inaccessible to applications, the special
+ handling is no longer useful.
+ Added PNG_SAFE_LIMITS feature to pnglibconf.dfa, pngpriv.h, and new
+ pngusr.dfa to reset the user limits to safe ones if PNG_SAFE_LIMITS is
+ defined. To enable, use "CPPFLAGS=-DPNG_SAFE_LIMITS_SUPPORTED=1" on the
+ configure command or put #define PNG_SAFE_LIMITS_SUPPORTED in
+ pnglibconf.h.prebuilt and pnglibconf.h.
+
+Version 1.6.0beta14 [February 27, 2012]
+ Added information about the new limits in the manual.
+ Updated Makefile.in
+
+Version 1.6.0beta15 [March 2, 2012]
+ Removed unused "current_text" members of png_struct and the png_free()
+ of png_ptr->current_text from pngread.c
+ Rewrote pngstest.c for substantial speed improvement.
+ Fixed transparent pixel and 16-bit rgb tests in pngstest and removed a
+ spurious check in pngwrite.c
+ Added PNG_IMAGE_FLAG_FAST for the benefit of applications that store
+ intermediate files, or intermediate in-memory data, while processing
+ image data with the simplified API. The option makes the files larger
+ but faster to write and read. pngstest now uses this by default; this
+ can be disabled with the --slow option.
+ Improved pngstest fine tuning of error numbers, new test file generator.
+ The generator generates images that test the full range of sample values,
+ allow the error numbers in pngstest to be tuned and checked. makepng
+ also allows generation of images with extra chunks, although this is
+ still work-in-progress.
+ Added check for invalid palette index while reading.
+ Fixed some bugs in ICC profile writing. The code should now accept
+ all potentially valid ICC profiles and reject obviously invalid ones.
+ It now uses png_error() to do so rather than casually writing a PNG
+ without the necessary color data.
+ Removed whitespace from the end of lines in all source files and scripts.
+
+Version 1.6.0beta16 [March 6, 2012]
+ Relocated palette-index checking function from pngrutil.c to pngtrans.c
+ Added palette-index checking while writing.
+ Changed png_inflate() and calling routines to avoid overflow problems.
+ This is an intermediate check-in that solves the immediate problems and
+ introduces one performance improvement (avoiding a copy via png_ptr->zbuf.)
+ Further changes will be made to make ICC profile handling more secure.
+ Fixed build warnings (MSVC, GCC, GCC v3). Cygwin GCC with default options
+ declares 'index' as a global, causing a warning if it is used as a local
+ variable. GCC 64-bit warns about assigning a (size_t) (unsigned 64-bit)
+ to an (int) (signed 32-bit). MSVC, however, warns about using the
+ unary '-' operator on an unsigned value (even though it is well defined
+ by ANSI-C to be ~x+1). The padding calculation was changed to use a
+ different method. Removed the tests on png_ptr->pass.
+ Added contrib/libtests/tarith.c to test internal arithmetic functions from
+ png.c. This is a libpng maintainer program used to validate changes to the
+ internal arithmetic functions.
+ Made read 'inflate' handling like write 'deflate' handling. The read
+ code now claims and releases png_ptr->zstream, like the write code.
+ The bug whereby the progressive reader failed to release the zstream
+ is now fixed, all initialization is delayed, and the code checks for
+ changed parameters on deflate rather than always calling
+ deflatedEnd/deflateInit.
+ Validate the zTXt strings in pngvalid.
+ Added code to validate the windowBits value passed to deflateInit2().
+ If the call to deflateInit2() is wrong a png_warning will be issued
+ (in fact this is harmless, but the PNG data produced may be sub-optimal).
+
+Version 1.6.0beta17 [March 10, 2012]
+ Fixed PNG_LIBPNG_BUILD_BASE_TYPE definition.
+ Reject all iCCP chunks after the first, even if the first one is invalid.
+ Deflate/inflate was reworked to move common zlib calls into single
+ functions [rw]util.c. A new shared keyword check routine was also added
+ and the 'zbuf' is no longer allocated on progressive read. It is now
+ possible to call png_inflate() incrementally. A warning is no longer
+ issued if the language tag or translated keyword in the iTXt chunk
+ has zero length.
+ If benign errors are disabled use maximum window on ancilliary inflate.
+ This works round a bug introduced in 1.5.4 where compressed ancillary
+ chunks could end up with a too-small windowBits value in the deflate
+ header.
+
+Version 1.6.0beta18 [March 16, 2012]
+ Issue a png_benign_error() instead of png_warning() about bad palette index.
+ In pngtest, treat benign errors as errors if "-strict" is present.
+ Fixed an off-by-one error in the palette index checking function.
+ Fixed a compiler warning under Cygwin (Windows-7, 32-bit system)
+ Revised example.c to put text strings in a temporary character array
+ instead of directly assigning string constants to png_textp members.
+ This avoids compiler warnings when -Wwrite-strings is enabled.
+ Added output flushing to aid debugging under Visual Studio. Unfortunately
+ this is necessary because the VS2010 output window otherwise simply loses
+ the error messages on error (they weren't flushed to the window before
+ the process exited, apparently!)
+ Added configuration support for benign errors and changed the read
+ default. Also changed some warnings in the iCCP and sRGB handling
+ from to benign errors. Configuration now makes read benign
+ errors warnings and write benign errors to errors by default (thus
+ changing the behavior on read). The simplified API always forces
+ read benign errors to warnings (regardless of the system default, unless
+ this is disabled in which case the simplified API can't be built.)
+
+Version 1.6.0beta19 [March 18, 2012]
+ Work around for duplicate row start calls; added warning messages.
+ This turns on PNG_FLAG_DETECT_UNINITIALIZED to detect app code that
+ fails to call one of the 'start' routines (not enabled in libpng-1.5
+ because it is technically an API change, since it did normally work
+ before.) It also makes duplicate calls to png_read_start_row (an
+ internal function called at the start of the image read) benign, as
+ they were before changes to use png_inflate_claim. Somehow webkit is
+ causing this to happen; this is probably a mis-feature in the zlib
+ changes so this commit is only a work-round.
+ Removed erroneous setting of DETECT_UNINITIALIZED and added more
+ checks. The code now does a png_error if an attempt is made to do the
+ row initialization twice; this is an application error and it has
+ serious consequences because the transform data in png_struct is
+ changed by each call.
+ Added application error reporting and added chunk names to read
+ benign errors; also added --strict to pngstest - not enabled
+ yet because a warning is produced.
+ Avoid the double gamma correction warning in the simplified API.
+ This allows the --strict option to pass in the pngstest checks
+
+Version 1.6.0beta20 [March 29, 2012]
+ Changed chunk handler warnings into benign errors, incrementally load iCCP
+ Added checksum-icc.c to contrib/tools
+ Prevent PNG_EXPAND+PNG_SHIFT doing the shift twice.
+ Recognize known sRGB ICC profiles while reading; prefer writing the
+ iCCP profile over writing the sRGB chunk, controlled by the
+ PNG_sRGB_PROFILE_CHECKS option.
+ Revised png_set_text_2() to avoid potential memory corruption (fixes
+ CVE-2011-3048, also known as CVE-2012-3425).
+
+Version 1.6.0beta21 [April 27, 2012]
+ Revised scripts/makefile.darwin: use system zlib; remove quotes around
+ architecture list; add missing ppc architecture; add architecture options
+ to shared library link; don't try to create a shared lib based on missing
+ RELEASE variable.
+ Enable png_set_check_for_invalid_index() for both read and write.
+ Removed #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED in pngpriv.h around
+ declaration of png_handle_unknown().
+ Added -lssp_nonshared in a comment in scripts/makefile.freebsd
+ and changed deprecated NOOBJ and NOPROFILE to NO_OBJ and NO_PROFILE.
+
+Version 1.6.0beta22 [May 23, 2012]
+ Removed need for -Wno-cast-align with clang. clang correctly warns on
+ alignment increasing pointer casts when -Wcast-align is passed. This
+ fixes the cases that clang warns about either by eliminating the
+ casts from png_bytep to png_uint_16p (pngread.c), or, for pngrutil.c
+ where the cast is previously verified or pngstest.c where it is OK, by
+ introducing new png_aligncast macros to do the cast in a way that clang
+ accepts.
+
+Version 1.6.0beta23 [June 6, 2012]
+ Revised CMakeLists.txt to not attempt to make a symlink under mingw.
+ Made fixes for new optimization warnings from gcc 4.7.0. The compiler
+ performs an optimization which is safe; however it then warns about it.
+ Changing the type of 'palette_number' in pngvalid.c removes the warning.
+ Do not depend upon a GCC feature macro being available for use in generating
+ the linker mapfile symbol prefix.
+ Improved performance of new do_check_palette_indexes() function (only
+ update the value when it actually increases, move test for whether
+ the check is wanted out of the function.
+
+Version 1.6.0beta24 [June 7, 2012]
+ Don't check palette indexes if num_palette is 0 (as it can be in MNG files).
+
+Version 1.6.0beta25 [June 16, 2012]
+ Revised png_set_keep_unknown_chunks() so num_chunks < 0 means ignore all
+ unknown chunks and all known chunks except for IHDR, PLTE, tRNS, IDAT,
+ and IEND. Previously it only meant ignore all unknown chunks, the
+ same as num_chunks == 0. Revised png_image_skip_unused_chunks() to
+ provide a list of chunks to be processed instead of a list of chunks to
+ ignore. Revised contrib/gregbook/readpng2.c accordingly.
+
+Version 1.6.0beta26 [July 10, 2012]
+ Removed scripts/makefile.cegcc from the *.zip and *.7z distributions; it
+ depends on configure, which is not included in those archives.
+ Moved scripts/chkfmt to contrib/tools.
+ Changed "a+w" to "u+w" in Makefile.in to fix CVE-2012-3386.
+
+Version 1.6.0beta27 [August 11, 2012]
+ Do not compile PNG_DEPRECATED, PNG_ALLOC and PNG_PRIVATE when __GNUC__ < 3.
+ Do not use __restrict when GNUC is <= 3.1
+ Removed references to png_zalloc() and png_zfree() from the manual.
+ Fixed configurations where floating point is completely disabled. Because
+ of the changes to support symbol prefixing PNG_INTERNAL_FUNCTION declares
+ floating point APIs during libpng builds even if they are completely
+ disabled. This requires the png floating point types (png_double*) to be
+ declared even though the functions are never actually defined. This
+ change provides a dummy definition so that the declarations work, yet any
+ implementation will fail to compile because of an incomplete type.
+ Re-eliminated the use of strcpy() in pngtest.c. An unncessary use of
+ strcpy() was accidentally re-introduced in libpng16; this change replaces
+ it with strncpy().
+ Eliminated use of png_sizeof(); use sizeof() instead.
+ Use a consistent style for (sizeof type) and (sizeof (array))
+ Cleanup of png_set_filler(). This function does very different things on
+ read and write. In libpng 1.6 the two cases can be distinguished and
+ considerable code cleanup, and extra error checking, is possible. This
+ makes calls on the write side that have no effect be ignored with a
+ png_app_error(), which can be disabled in the app using
+ png_set_benign_errors(), and removes the spurious use of usr_channels
+ on the read side.
+ Insist on autotools 1.12.1 for git builds because there are security issues
+ with 1.12 and insisting on anything less would allow 1.12 to be used.
+ Removed info_ptr->signature[8] from WRITE-only builds.
+ Add some conditions for compiling png_fixed(). This is a small function
+ but it requires "-lm" on some platforms.
+ Cause pngtest --strict to fail on any warning from libpng (not just errors)
+ and cause it not to fail at the comparison step if libpng lacks support
+ for writing chunks that it reads from the input (currently only implemented
+ for compressed text chunks).
+ Make all three "make check" test programs work without READ or WRITE support.
+ Now "make check" will succeed even if libpng is compiled with -DPNG_NO_READ
+ or -DPNG_NO_WRITE. The tests performed are reduced, but the basic reading
+ and writing of a PNG file is always tested by one or more of the tests.
+ Consistently use strlen(), memset(), memcpy(), and memcmp() instead of the
+ png_strlen(), png_memset(), png_memcpy(), and png_memcmp() macros.
+ Removed the png_sizeof(), png_strlen(), png_memset(), png_memcpy(), and
+ png_memcmp() macros.
+ Work around gcc 3.x and Microsoft Visual Studio 2010 complaints. Both object
+ to the split initialization of num_chunks.
+
+Version 1.6.0beta28 [August 29, 2012]
+ Unknown handling fixes and clean up. This adds more correct option
+ control of the unknown handling, corrects the pre-existing bug where
+ the per-chunk 'keep' setting is ignored and makes it possible to skip
+ IDAT chunks in the sequential reader (broken in earlier 1.6 versions).
+ There is a new test program, test-unknown.c, which is a work in progress
+ (not currently part of the test suite). Comments in the header files now
+ explain how the unknown handling works.
+ Allow fine grain control of unknown chunk APIs. This change allows
+ png_set_keep_unknown_chunks() to be turned off if not required and causes
+ both read and write to behave appropriately (on read this is only possible
+ if the user callback is used to handle unknown chunks). The change
+ also removes the support for storing unknown chunks in the info_struct
+ if the only unknown handling enabled is via the callback, allowing libpng
+ to be configured with callback reading and none of the unnecessary code.
+ Corrected fix for unknown handling in pngtest. This reinstates the
+ libpng handling of unknown chunks other than vpAg and sTER (including
+ unsafe-to-copy chunks which were dropped before) and eliminates the
+ repositioning of vpAg and sTER in pngtest.png by changing pngtest.png
+ (so the chunks are where libpng would put them).
+ Added "tunknown" test and corrected a logic error in png_handle_unknown()
+ when SAVE support is absent. Moved the shell test scripts for
+ contrib/libtests from the libpng top directory to contrib/libtests.
+ png_handle_unknown() must always read or skip the chunk, if
+ SAVE_UNKNOWN_CHUNKS is turned off *and* the application does not set
+ a user callback an unknown chunk will not be read, leading to a read
+ error, which was revealed by the "tunknown" test.
+ Cleaned up and corrected ICC profile handling.
+ contrib/libtests/makepng: corrected 'rgb' and 'gray' cases. profile_error
+ messages could be truncated; made a correct buffer size calculation and
+ adjusted pngerror.c appropriately. png_icc_check_* checking improved;
+ changed the functions to receive the correct color type of the PNG on read
+ or write and check that it matches the color space of the profile (despite
+ what the comments said before, there is danger in assuming the app will
+ cope correctly with an RGB profile on a grayscale image and, since it
+ violates the PNG spec, allowing it is certain to produce inconsistent
+ app behavior and might even cause app crashes.) Check that profiles
+ contain the tags needed to process the PNG (tags all required by the ICC
+ spec). Removed unused PNG_STATIC from pngpriv.h.
+
+Version 1.6.0beta29 [September 4, 2012]
+ Fixed the simplified API example programs to add the *colormap parameter
+ to several of he API and improved the error message if the version field
+ is not set.
+ Added contrib/examples/* to the *.zip and *.7z distributions.
+ Updated simplified API synopses and description of the png_image structure
+ in the manual.
+ Made makepng and pngtest produce identical PNGs, add "--relaxed" option
+ to pngtest. The "--relaxed" option turns off the benign errors that are
+ enabled by default in pre-RC builds. makepng can now write ICC profiles
+ where the length has not been extended to a multiple of 4, and pngtest
+ now intercepts all libpng errors, allowing the previously-introduced
+ "--strict test" on no warnings to actually work.
+ Improved ICC profile handling including cHRM chunk generation and fixed
+ Cygwin+MSVC build errors. The ICC profile handling now includes more
+ checking. Several errors that caused rejection of the profile are now
+ handled with a warning in such a way that the invalid profiles will be
+ read by default in release (but not pre-RC) builds but will not be
+ written by default. The easy part of handling the cHRM chunk is written,
+ where the ICC profile contains the required data. The more difficult
+ part plus guessing a gAMA value requires code to pass selected RGB values
+ through the profile.
+
+Version 1.6.0beta30 [October 24, 2012]
+ Changed ICC profile matrix/vector types to not depend on array type rules.
+ By the ANSI-C standard the new types should be identical to the previous
+ versions, and all known versions of gcc tested with the previous versions
+ except for GCC-4.2.1 work with this version. The change makes the ANSI-C
+ rule that const applied to an array of elements applies instead to the
+ elements in the array moot by explicitly applying const to the base
+ elements of the png_icc_matrix and png_icc_vector types. The accidental
+ (harmless) 'const' previously applied to the parameters of two of the
+ functions have also been removed.
+ Added a work around for GCC 4.2 optimization bug.
+ Marked the broken (bad white point) original HP sRGB profiles correctly and
+ correct comments.
+ Added -DZ_SOLO to contrib/pngminim/*/makefile to work with zlib-1.2.7
+ Use /MDd for vstudio debug builds. Also added pngunkown to the vstudio
+ builds, fixed build errors and corrected a minor exit code error in
+ pngvalid if the 'touch' file name is invalid.
+ Add updated WARNING file to projects/vstudio from libpng 1.5/vstudio
+ Fixed build when using #define PNG_NO_READ_GAMMA in png_do_compose() in
+ pngrtran.c (Domani Hannes).
+
+Version 1.6.0beta31 [November 1, 2012]
+ Undid the erroneous change to vstudio/pngvalid build in libpng-1.6.0beta30.
+ Made pngvalid so that it will build outside the libpng source tree.
+ Made builds -DPNG_NO_READ_GAMMA compile (the unit tests still fail).
+ Made PNG_NO_READ_GAMMA switch off interfaces that depend on READ_GAMMA.
+ Prior to 1.6.0 switching off READ_GAMMA did unpredictable things to the
+ interfaces that use it (specifically, png_do_background in 1.4 would
+ simply display composite for grayscale images but do composition
+ with the incorrect arithmetic for color ones). In 1.6 the semantic
+ of -DPNG_NO_READ_GAMMA is changed to simply disable any interface that
+ depends on it; this obliges people who set it to consider whether they
+ really want it off if they happen to use any of the interfaces in
+ question (typically most users who disable it won't).
+ Fixed GUIDs in projects/vstudio. Some were duplicated or missing,
+ resulting in VS2010 having to update the files.
+ Removed non-working ICC profile support code that was mostly added to
+ libpng-1.6.0beta29 and beta30. There was too much code for too little
+ gain; implementing full ICC color correction may be desireable but is left
+ up to applications.
+
+Version 1.6.0beta32 [November 25, 2012]
+ Fixed an intermittent SEGV in pngstest due to an uninitialized array element.
+ Added the ability for contrib/libtests/makepng.c to make a PNG with just one
+ color. This is useful for debugging pngstest color inaccuracy reports.
+ Fixed error checking in the simplified write API (Olaf van der Spek)
+ Made png_user_version_check() ok to use with libpng version 1.10.x and later.
+
+Version 1.6.0beta33 [December 15, 2012]
+ Fixed typo in png.c (PNG_SET_CHUNK_MALLOC_MAX should be PNG_CHUNK_MALLOC_MAX)
+ that causes the MALLOC_MAX limit not to work (John Bowler)
+ Change png_warning() to png_app_error() in pngwrite.c and comment the
+ fall-through condition.
+ Change png_warning() to png_app_warning() in png_write_tRNS().
+ Rearranged the ARM-NEON optimizations: Isolated the machine specific code
+ to the hardware subdirectory and added comments to pngrutil.c so that
+ implementors of other optimizations know what to do.
+ Fixed cases of unquoted DESTDIR in Makefile.am
+ Rebuilt Makefile.in, etc., with autoconf-2.69 and automake-1.12.5.
+
+Version 1.6.0beta34 [December 19, 2012]
+ Cleaned up whitespace in the synopsis portion of the manpage "libpng.3"
+ Disassembled the version number in scripts/options.awk (necessary for
+ building on SunOs).
+
+Version 1.6.0beta35 [December 23, 2012]
+ Made default Zlib compression settings be configurable. This adds #defines to
+ pnglibconf.h to control the defaults.
+ Fixed Windows build issues, enabled ARM compilation. Various warnings issued
+ by earlier versions of GCC fixed for Cygwin and Min/GW (which both use old
+ GCCs.) ARM support is enabled by default in zlib.props (unsupported by
+ Microsoft) and ARM compilation is made possible by deleting the check for
+ x86. The test programs cannot be run because they are not signed.
+
+Version 1.6.0beta36 [January 2, 2013]
+ Discontinued distributing libpng-1.x.x.tar.bz2.
+ Discontinued distributing libpng-1.7.0-1.6.0-diff.txt and similar.
+ Rebuilt configure with autoconf-2.69 (inadvertently not done in beta33)
+ Fixed 'make distcheck' on SUN OS - libpng.so was not being removed
+
+Version 1.6.0beta37 [January 10, 2013]
+ Fixed conceivable but difficult to repro overflow. Also added two test
+ programs to generate and test a PNG which should have the problem.
+
+Version 1.6.0beta39 [January 19, 2013]
+ Again corrected attempt at overflow detection in png_set_unknown_chunks()
+ (CVE-2013-7353). Added overflow detection in png_set_sPLT() and
+ png_set_text_2() (CVE-2013-7354).
+
+Version 1.6.0beta40 [January 20, 2013]
+ Use consistent handling of overflows in text, sPLT and unknown png_set_* APIs
+
+Version 1.6.0rc01 [January 26, 2013]
+ No changes.
+
+Version 1.6.0rc02 [February 4, 2013]
+ Added png_get_palette_max() function.
+
+Version 1.6.0rc03 [February 5, 2013]
+ Fixed the png_get_palette_max API.
+
+Version 1.6.0rc04 [February 7, 2013]
+ Turn serial tests back on (recently turned off by autotools upgrade).
+
+Version 1.6.0rc05 [February 8, 2013]
+ Update manual about png_get_palette_max().
+
+Version 1.6.0rc06 [February 9, 2013]
+ Fixed missing dependency in --prefix builds The intermediate
+ internal 'prefix.h' file can only be generated correctly after
+ pnglibconf.h, however the dependency was not in Makefile.am. The
+ symptoms are unpredictable depending on the order make chooses to
+ build pngprefix.h and pnglibconf.h, often the error goes unnoticed
+ because there is a system pnglibconf.h to use instead.
+
+Version 1.6.0rc07 [February 10, 2013]
+ Enclosed the new png_get_palette_max in #ifdef PNG_GET_PALETTE_MAX_SUPPORTED
+ block, and revised pnglibconf.h and pnglibconf.h.prebuilt accordingly.
+
+Version 1.6.0rc08 [February 10, 2013]
+ Fix typo in png.h #ifdef
+
+Version 1.6.0 [February 14, 2013]
+ No changes.
+
+Version 1.6.1beta01 [February 16, 2013]
+ Made symbol prefixing work with the ARM neon optimizations. Also allow
+ pngpriv.h to be included for preprocessor definitions only, so it can
+ be used in non-C/C++ files. Back ported from libpng 1.7.
+ Made sRGB check numbers consistent.
+ Ported libpng 1.5 options.awk/dfn file handling to 1.6, fixed one bug.
+ Removed cc -E workround, corrected png_get_palette_max API Tested on
+ SUN OS cc 5.9, which demonstrates the tokenization problem previously
+ avoided by using /lib/cpp. Since all .dfn output is now protected in
+ double quotes unless it is to be macro substituted the fix should
+ work everywhere.
+ Enabled parallel tests - back ported from libpng-1.7.
+ scripts/pnglibconf.dfa formatting improvements back ported from libpng17.
+ Fixed a race condition in the creation of the build 'scripts' directory
+ while building with a parallel make.
+ Use approved/supported Android method to check for NEON, use Linux/POSIX
+ 1003.1 API to check /proc/self/auxv avoiding buffer allocation and other
+ library calls (ported from libpng15).
+
+Version 1.6.1beta02 [February 19, 2013]
+ Use parentheses more consistently in "#if defined(MACRO)" tests.
+ Folded long lines.
+ Reenabled code to allow zero length PLTE chunks for MNG.
+
+Version 1.6.1beta03 [February 22, 2013]
+ Fixed ALIGNED_MEMORY support.
+ Added a new configure option:
+ --enable-arm-neon=always will stop the run-time checks. New checks
+ within arm/arm_init.c will cause the code not to be compiled unless
+ __ARM_NEON__ is set. This should make it fail safe (if someone asks
+ for it on then the build will fail if it can't be done.)
+ Updated the INSTALL document.
+
+Version 1.6.1beta04 [February 27, 2013]
+ Revised INSTALL to recommend using CPPFLAGS instead of INCLUDES.
+ Revised scripts/makefile.freebsd to respect ZLIBLIB and ZLIBINC.
+ Revised scripts/dfn.awk to work with the buggy MSYS awk that has trouble
+ with CRLF line endings.
+
+Version 1.6.1beta05 [March 1, 2013]
+ Avoid a possible memory leak in contrib/gregbook/readpng.c
+
+Version 1.6.1beta06 [March 4, 2013]
+ Better documentation of unknown handling API interactions.
+ Corrected Android builds and corrected libpng.vers with symbol
+ prefixing. It also makes those tests compile and link on Android.
+ Added an API png_set_option() to set optimization options externally,
+ providing an alternative and general solution for the non-portable
+ run-time tests used by the ARM Neon code, using the PNG_ARM_NEON option.
+ The order of settings vs options in pnglibconf.h is reversed to allow
+ settings to depend on options and options can now set (or override) the
+ defaults for settings.
+
+Version 1.6.1beta07 [March 7, 2013]
+ Corrected simplified API default gamma for color-mapped output, added
+ a flag to change default. In 1.6.0 when the simplified API was used
+ to produce color-mapped output from an input image with no gamma
+ information the gamma assumed for the input could be different from
+ that assumed for non-color-mapped output. In particular 16-bit depth
+ input files were assumed to be sRGB encoded, whereas in the 'direct'
+ case they were assumed to have linear data. This was an error. The
+ fix makes the simplified API treat all input files the same way and
+ adds a new flag to the png_image::flags member to allow the
+ application/user to specify that 16-bit files contain sRGB data
+ rather than the default linear.
+ Fixed bugs in the pngpixel and makepng test programs.
+
+Version 1.6.1beta08 [March 7, 2013]
+ Fixed CMakelists.txt to allow building a single variant of the library
+ (Claudio Bley):
+ Introduced a PNG_LIB_TARGETS variable that lists all activated library
+ targets. It is an error if this variable ends up empty, ie. you have
+ to build at least one library variant.
+ Made the *_COPY targets only depend on library targets actually being build.
+ Use PNG_LIB_TARGETS to unify a code path.
+ Changed the CREATE_SYMLINK macro to expect the full path to a file as the
+ first argument. When symlinking the filename component of that path is
+ determined and used as the link target.
+ Use copy_if_different in the CREATE_SYMLINK macro.
+
+Version 1.6.1beta09 [March 13, 2013]
+ Eliminated two warnings from the Intel C compiler. The warnings are
+ technically valid, although a reasonable treatment of division would
+ show it to be incorrect.
+
+Version 1.6.1rc01 [March 21, 2013]
+ No changes.
+
+Version 1.6.1 [March 28, 2013]
+ No changes.
+
+Version 1.6.2beta01 [April 14, 2013]
+ Updated documentation of 1.5.x to 1.6.x changes in iCCP chunk handling.
+ Fixed incorrect warning of excess deflate data. End condition - the
+ warning would be produced if the end of the deflate stream wasn't read
+ in the last row. The warning is harmless.
+ Corrected the test on user transform changes on read. It was in the
+ png_set of the transform function, but that doesn't matter unless the
+ transform function changes the rowbuf size, and that is only valid if
+ transform_info is called.
+ Corrected a misplaced closing bracket in contrib/libtests/pngvalid.c
+ (Flavio Medeiros).
+ Corrected length written to uncompressed iTXt chunks (Samuli Suominen).
+ Bug was introduced in libpng-1.6.0.
+
+Version 1.6.2rc01 [April 18, 2013]
+ Added contrib/tools/fixitxt.c, to repair the erroneous iTXt chunk length
+ written by libpng-1.6.0 and 1.6.1.
+ Disallow storing sRGB information when the sRGB is not supported.
+
+Version 1.6.2rc02 [April 18, 2013]
+ Merge pngtest.c with libpng-1.7.0
+
+Version 1.6.2rc03 [April 22, 2013]
+ Trivial spelling cleanup.
+
+Version 1.6.2rc04 and 1.6.2rc05 [omitted]
+
+Version 1.6.2rc06 [April 24, 2013]
+ Reverted to version 1.6.2rc03. Recent changes to arm/neon support
+ have been ported to libpng-1.7.0beta09 and will reappear in version
+ 1.6.3beta01.
+
+Version 1.6.2 [April 25, 2013]
+ No changes.
+
+Version 1.6.3beta01 [April 25, 2013]
+ Revised stack marking in arm/filter_neon.S and configure.ac.
+ Ensure that NEON filter stuff is completely disabled when switched 'off'.
+ Previously the ARM NEON specific files were still built if the option
+ was switched 'off' as opposed to being explicitly disabled.
+
+Version 1.6.3beta02 [April 26, 2013]
+ Test for 'arm*' not just 'arm' in the host_cpu configure variable.
+ Rebuilt the configure scripts.
+
+Version 1.6.3beta03 [April 30, 2013]
+ Expanded manual paragraph about writing private chunks, particularly
+ the need to call png_set_keep_unknown_chunks() when writing them.
+ Avoid dereferencing NULL pointer possibly returned from
+ png_create_write_struct() (Andrew Church).
+
+Version 1.6.3beta05 [May 9, 2013]
+ Calculate our own zlib windowBits when decoding rather than trusting the
+ CMF bytes in the PNG datastream.
+ Added an option to force maximum window size for inflating, which was
+ the behavior of libpng15 and earlier, via a new PNG_MAXIMUM_INFLATE_WINDOW
+ option for png_set_options().
+ Added png-fix-itxt and png-fix-too-far-back to the built programs and
+ removed warnings from the source code and timepng that are revealed as
+ a result.
+ Detect wrong libpng versions linked to png-fix-too-far-back, which currently
+ only works with libpng versions that can be made to reliably fail when
+ the deflate data contains an out-of-window reference. This means only
+ 1.6 and later.
+ Fixed gnu issues: g++ needs a static_cast, gcc 4.4.7 has a broken warning
+ message which it is easier to work round than ignore.
+ Updated contrib/pngminus/pnm2png.c (Paul Stewart):
+ Check for EOF
+ Ignore "#" delimited comments in input file to pnm2png.c.
+ Fixed whitespace handling
+ Added a call to png_set_packing()
+ Initialize dimension values so if sscanf fails at least we have known
+ invalid values.
+ Attempt to detect configuration issues with png-fix-too-far-back, which
+ requires both the correct libpng and the correct zlib to function
+ correctly.
+ Check ZLIB_VERNUM for mismatches, enclose #error in quotes
+ Added information in the documentation about problems with and fixes for
+ the bad CRC and bad iTXt chunk situations.
+
+Version 1.6.3beta06 [May 12, 2013]
+ Allow contrib/pngminus/pnm2png.c to compile without WRITE_INVERT and
+ WRITE_PACK supported (writes error message that it can't read P1 or
+ P4 PBM files).
+ Improved png-fix-too-far-back usage message, added --suffix option.
+ Revised contrib/pngminim/*/makefile to generate pnglibconf.h with the
+ right zlib header files.
+ Separated CPPFLAGS and CFLAGS in contrib/pngminim/*/makefile
+
+Version 1.6.3beta07 [June 8, 2013]
+ Removed a redundant test in png_set_IHDR().
+ Added set(CMAKE_CONFIGURATION_TYPES ...) to CMakeLists.txt (Andrew Hundt)
+ Deleted set(CMAKE_BUILD_TYPE) block from CMakeLists.txt
+ Enclose the prototypes for the simplified write API in
+ #ifdef PNG_STDIO_SUPPORTED/#endif
+ Make ARM NEON support work at compile time (not just configure time).
+ This moves the test on __ARM_NEON__ into pngconf.h to avoid issues when
+ using a compiler that compiles for multiple architectures at one time.
+ Removed PNG_FILTER_OPTIMIZATIONS and PNG_ARM_NEON_SUPPORTED from
+ pnglibconf.h, allowing more of the decisions to be made internally
+ (pngpriv.h) during the compile. Without this, symbol prefixing is broken
+ under certain circumstances on ARM platforms. Now only the API parts of
+ the optimizations ('check' vs 'api') are exposed in the public header files
+ except that the new setting PNG_ARM_NEON_OPT documents how libpng makes the
+ decision about whether or not to use the optimizations.
+ Protect symbol prefixing against CC/CPPFLAGS/CFLAGS useage.
+ Previous iOS/Xcode fixes for the ARM NEON optimizations moved the test
+ on __ARM_NEON__ from configure time to compile time. This breaks symbol
+ prefixing because the definition of the special png_init_filter_functions
+ call was hidden at configure time if the relevant compiler arguments are
+ passed in CFLAGS as opposed to CC. This change attempts to avoid all
+ the confusion that would result by declaring the init function even when
+ it is not used, so that it will always get prefixed.
+
+Version 1.6.3beta08 [June 18, 2013]
+ Revised libpng.3 so that "doclifter" can process it.
+
+Version 1.6.3beta09 [June 27, 2013]
+ Revised example.c to illustrate use of PNG_DEFAULT_sRGB and PNG_GAMMA_MAC_18
+ as parameters for png_set_gamma(). These have been available since
+ libpng-1.5.4.
+ Renamed contrib/tools/png-fix-too-far-back.c to pngfix.c and revised it
+ to check all compressed chunks known to libpng.
+
+Version 1.6.3beta10 [July 5, 2013]
+ Updated documentation to show default behavior of benign errors correctly.
+ Only compile ARM code when PNG_READ_SUPPORTED is defined.
+ Fixed undefined behavior in contrib/tools/pngfix.c and added new strip
+ option. pngfix relied on undefined behavior and even a simple change from
+ gcc to g++ caused it to fail. The new strip option 'unsafe' has been
+ implemented and is the default if --max is given. Option names have
+ been clarified, with --strip=transform now stripping the bKGD chunk,
+ which was stripped previously with --strip=unused.
+ Added all documented chunk types to pngpriv.h
+ Unified pngfix.c source with libpng17.
+
+Version 1.6.3rc01 [July 11, 2013]
+ No changes.
+
+Version 1.6.3 [July 18, 2013]
+ Revised manual about changes in iTXt chunk handling made in libpng-1.6.0.
+ Added "/* SAFE */" comments in pngrutil.c and pngrtran.c where warnings
+ may be erroneously issued by code-checking applications.
+
+Version 1.6.4beta01 [August 21, 2013]
+ Added information about png_set_options() to the manual.
+ Delay calling png_init_filter_functions() until a row with nonzero filter
+ is found.
+
+Version 1.6.4beta02 [August 30, 2013]
+ Fixed inconsistent conditional compilation of png_chunk_unknown_handling()
+ prototype, definition, and usage. Made it depend on
+ PNG_HANDLE_AS_UNKNOWN_SUPPORTED everywhere.
+
+Version 1.6.4rc01 [September 5, 2013]
+ No changes.
+
+Version 1.6.4 [September 12, 2013]
+ No changes.
+
+Version 1.6.5 [September 14, 2013]
+ Removed two stray lines of code from arm/arm_init.c.
+
+Version 1.6.6 [September 16, 2013]
+ Removed two stray lines of code from arm/arm_init.c, again.
+
+Version 1.6.7beta01 [September 30, 2013]
+ Revised unknown chunk code to correct several bugs in the NO_SAVE_/NO_WRITE
+ combination
+ Allow HANDLE_AS_UNKNOWN to work when other options are configured off. Also
+ fixed the pngminim makefiles to work when $(MAKEFLAGS) contains stuff
+ which terminates the make options (as by default in recent versions of
+ Gentoo).
+ Avoid up-cast warnings in pngvalid.c. On ARM the alignment requirements of
+ png_modifier are greater than that of png_store and as a consequence
+ compilation of pngvalid.c results in a warning about increased alignment
+ requirements because of the bare cast to (png_modifier*). The code is safe,
+ because the pointer is known to point to a stack allocated png_modifier,
+ but this change avoids the warning.
+ Fixed default behavior of ARM_NEON_API. If the ARM NEON API option was
+ compiled without the CHECK option it defaulted to on, not off.
+ Check user callback behavior in pngunknown.c. Previous versions compiled
+ if SAVE_UNKNOWN was not available but did nothing since the callback
+ was never implemented.
+ Merged pngunknown.c with 1.7 version and back ported 1.7 improvements/fixes
+
+Version 1.6.7beta02 [October 12, 2013]
+ Made changes for compatibility with automake 1.14:
+ 1) Added the 'compile' program to the list of programs that must be cleaned
+ in autogen.sh
+ 2) Added 'subdir-objects' which causes .c files in sub-directories to be
+ compiled such that the corresponding .o files are also in the
+ sub-directory. This is because automake 1.14 warns that the
+ current behavior of compiling to the top level directory may be removed
+ in the future.
+ 3) Updated dependencies on pnglibconf.h to match the new .o locations and
+ added all the files in contrib/libtests and contrib/tools that depend
+ on pnglibconf.h
+ 4) Added 'BUILD_SOURCES = pnglibconf.h'; this is the automake recommended
+ way of handling the dependencies of sources that are machine generated;
+ unfortunately it only works if the user does 'make all' or 'make check',
+ so the dependencies (3) are still required.
+ Cleaned up (char*) casts of zlib messages. The latest version of the Intel C
+ compiler complains about casting a string literal as (char*), so copied the
+ treatment of z_const from the library code into pngfix.c
+ Simplified error message code in pngunknown. The simplification has the
+ useful side effect of avoiding a bogus warning generated by the latest
+ version of the Intel C compiler (it objects to
+ condition ? string-literal : string-literal).
+ Make autogen.sh work with automake 1.13 as well as 1.14. Do this by always
+ removing the 1.14 'compile' script but never checking for it.
+
+Version 1.6.7beta03 [October 19, 2013]
+ Added ARMv8 support (James Yu <james.yu at linaro.org>). Added file
+ arm/filter_neon_intrinsics.c; enable with -mfpu=neon.
+ Revised pngvalid to generate size images with as many filters as it can
+ manage, limited by the number of rows.
+ Cleaned up ARM NEON compilation handling. The tests are now in pngpriv.h
+ and detect the broken GCC compilers.
+
+Version 1.6.7beta04 [October 26, 2013]
+ Allow clang derived from older GCC versions to use ARM intrinsics. This
+ causes all clang builds that use -mfpu=neon to use the intrinsics code,
+ not the assembler code. This has only been tested on iOS 7. It may be
+ necessary to exclude some earlier clang versions but this seems unlikely.
+ Changed NEON implementation selection mechanism. This allows assembler
+ or intrinsics to be turned on at compile time during the build by defining
+ PNG_ARM_NEON_IMPLEMENTATION to the correct value (2 or 1). This macro
+ is undefined by default and the build type is selected in pngpriv.h.
+
+Version 1.6.7rc01 [November 2, 2013]
+ No changes.
+
+Version 1.6.7rc02 [November 7, 2013]
+ Fixed #include in filter_neon_intrinsics.c and ctype macros. The ctype char
+ checking macros take an unsigned char argument, not a signed char.
+
+Version 1.6.7 [November 14, 2013]
+ No changes.
+
+Version 1.6.8beta01 [November 24, 2013]
+ Moved prototype for png_handle_unknown() in pngpriv.h outside of
+ the #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED/#endif block.
+ Added "-Wall" to CFLAGS in contrib/pngminim/*/makefile
+ Conditionally compile some unused functions reported by -Wall in
+ pngminim.
+ Fixed 'minimal' builds. Various obviously useful minimal configurations
+ don't build because of missing contrib/libtests test programs and
+ overly complex dependencies in scripts/pnglibconf.dfa. This change
+ adds contrib/conftest/*.dfa files that can be used in automatic build
+ scripts to ensure that these configurations continue to build.
+ Enabled WRITE_INVERT and WRITE_PACK in contrib/pngminim/encoder.
+ Fixed pngvalid 'fail' function declaration on the Intel C Compiler.
+ This reverts to the previous 'static' implementation and works round
+ the 'unused static function' warning by using PNG_UNUSED().
+
+Version 1.6.8beta02 [November 30, 2013]
+ Removed or marked PNG_UNUSED some harmless "dead assignments" reported
+ by clang scan-build.
+ Changed tabs to 3 spaces in png_debug macros and changed '"%s"m'
+ to '"%s" m' to improve portability among compilers.
+ Changed png_free_default() to free() in pngtest.c
+
+Version 1.6.8rc01 [December 12, 2013]
+ Tidied up pngfix inits and fixed pngtest no-write builds.
+
+Version 1.6.8rc02 [December 14, 2013]
+ Handle zero-length PLTE chunk or NULL palette with png_error()
+ instead of png_chunk_report(), which by default issues a warning
+ rather than an error, leading to later reading from a NULL pointer
+ (png_ptr->palette) in png_do_expand_palette(). This is CVE-2013-6954
+ and VU#650142. Libpng-1.6.1 through 1.6.7 are vulnerable.
+ Libpng-1.6.0 and earlier do not have this bug.
+
+Version 1.6.8 [December 19, 2013]
+ No changes.
+
+Version 1.6.9beta01 [December 26, 2013]
+ Bookkeeping: Moved functions around (no changes). Moved transform
+ function definitions before the place where they are called so that
+ they can be made static. Move the intrapixel functions and the
+ grayscale palette builder out of the png?tran.c files. The latter
+ isn't a transform function and is no longer used internally, and the
+ former MNG specific functions are better placed in pngread/pngwrite.c
+ Made transform implementation functions static. This makes the internal
+ functions called by png_do_{read|write}_transformations static. On an
+ x86-64 DLL build (Gentoo Linux) this reduces the size of the text
+ segment of the DLL by 1208 bytes, about 0.6%. It also simplifies
+ maintenance by removing the declarations from pngpriv.h and allowing
+ easier changes to the internal interfaces.
+ Rebuilt configure scripts with automake-1.14.1 and autoconf-2.69
+ in the tar distributions.
+
+Version 1.6.9beta02 [January 1, 2014]
+ Added checks for libpng 1.5 to pngvalid.c. This supports the use of
+ this version of pngvalid in libpng 1.5
+ Merged with pngvalid.c from libpng-1.7 changes to create a single
+ pngvalid.c
+ Removed #error macro from contrib/tools/pngfix.c (Thomas Klausner).
+ Merged pngrio.c, pngtrans.c, pngwio.c, and pngerror.c with libpng-1.7.0
+ Merged libpng-1.7.0 changes to make no-interlace configurations work
+ with test programs.
+ Revised pngvalid.c to support libpng 1.5, which does not support the
+ PNG_MAXIMUM_INFLATE_WINDOW option, so #define it out when appropriate in
+ pngvalid.c
+ Allow unversioned links created on install to be disabled in configure.
+ In configure builds 'make install' changes/adds links like png.h
+ and libpng.a to point to the newly installed, versioned, files (e.g.
+ libpng17/png.h and libpng17.a). Three new configure options and some
+ rearrangement of Makefile.am allow creation of these links to be disabled.
+
+Version 1.6.9beta03 [January 10, 2014]
+ Removed potentially misleading warning from png_check_IHDR().
+
+Version 1.6.9beta04 [January 20, 2014]
+ Updated scripts/makefile.* to use CPPFLAGS (Cosmin).
+ Added clang attribute support (Cosmin).
+
+Version 1.6.9rc01 [January 28, 2014]
+ No changes.
+
+Version 1.6.9rc02 [January 30, 2014]
+ Quiet an uninitialized memory warning from VC2013 in png_get_png().
+
+Version 1.6.9 [February 6, 2014]
+
+Version 1.6.10beta01 [February 9, 2014]
+ Backported changes from libpng-1.7.0beta30 and beta31:
+ Fixed a large number of instances where PNGCBAPI was omitted from
+ function definitions.
+ Added pngimage test program for png_read_png() and png_write_png()
+ with two new test scripts.
+ Removed dependence on !PNG_READ_EXPAND_SUPPORTED for calling
+ png_set_packing() in png_read_png().
+ Fixed combination of ~alpha with shift. On read invert alpha, processing
+ occurred after shift processing, which causes the final values to be
+ outside the range that should be produced by the shift. Reversing the
+ order on read makes the two transforms work together correctly and mirrors
+ the order used on write.
+ Do not read invalid sBIT chunks. Previously libpng only checked sBIT
+ values on write, so a malicious PNG writer could therefore cause
+ the read code to return an invalid sBIT chunk, which might lead to
+ application errors or crashes. Such chunks are now skipped (with
+ chunk_benign_error).
+ Make png_read_png() and png_write_png() prototypes in png.h depend
+ upon PNG_READ_SUPPORTED and PNG_WRITE_SUPPORTED.
+ Support builds with unsupported PNG_TRANSFORM_* values. All of the
+ PNG_TRANSFORM_* values are always defined in png.h and, because they
+ are used for both read and write in some cases, it is not reliable
+ to #if out ones that are totally unsupported. This change adds error
+ detection in png_read_image() and png_write_image() to do a
+ png_app_error() if the app requests something that cannot be done
+ and it adds corresponding code to pngimage.c to handle such options
+ by not attempting to test them.
+
+Version 1.6.10beta02 [February 23, 2014]
+ Moved redefines of png_error(), png_warning(), png_chunk_error(),
+ and png_chunk_warning() from pngpriv.h to png.h to make them visible
+ to libpng-calling applications.
+ Moved OS dependent code from arm/arm_init.c, to allow the included
+ implementation of the ARM NEON discovery function to be set at
+ build-time and provide sample implementations from the current code in the
+ contrib/arm-neon subdirectory. The __linux__ code has also been changed to
+ compile and link on Android by using /proc/cpuinfo, and the old linux code
+ is in contrib/arm-neon/linux-auxv.c. The new code avoids POSIX and Linux
+ dependencies apart from opening /proc/cpuinfo and is C90 compliant.
+ Check for info_ptr == NULL early in png_read_end() so we don't need to
+ run all the png_handle_*() and depend on them to return if info_ptr == NULL.
+ This improves the performance of png_read_end(png_ptr, NULL) and makes
+ it more robust against future programming errors.
+ Check for __has_extension before using it in pngconf.h, to
+ support older Clang versions (Jeremy Sequoia).
+ Treat CRC error handling with png_set_crc_action(), instead of with
+ png_set_benign_errors(), which has been the case since libpng-1.6.0beta18.
+ Use a user warning handler in contrib/gregbook/readpng2.c instead of default,
+ so warnings will be put on stderr even if libpng has CONSOLE_IO disabled.
+ Added png_ptr->process_mode = PNG_READ_IDAT_MODE in png_push_read_chunk
+ after recognizing the IDAT chunk, which avoids an infinite loop while
+ reading a datastream whose first IDAT chunk is of zero-length.
+ This fixes CERT VU#684412 and CVE-2014-0333.
+ Don't recognize known sRGB profiles as sRGB if they have been hacked,
+ but don't reject them and don't issue a copyright violation warning.
+
+Version 1.6.10beta03 [February 25, 2014]
+ Moved some documentation from png.h to libpng.3 and libpng-manual.txt
+ Minor editing of contrib/arm-neon/README and contrib/examples/*.c
+
+Version 1.6.10rc01 [February 27, 2014]
+ Fixed typos in the manual and in scripts/pnglibconf.dfa (CFLAGS -> CPPFLAGS
+ and PNG_USR_CONFIG -> PNG_USER_CONFIG).
+
+Version 1.6.10rc02 [February 28, 2014]
+ Removed unreachable return statement after png_chunk_error()
+ in pngrutil.c
+
+Version 1.6.10rc03 [March 4, 2014]
+ Un-deprecated png_data_freer().
+
+Version 1.6.10 [March 6, 2014]
+ No changes.
+
+Version 1.6.11beta01 [March 17, 2014]
+ Use "if (value != 0)" instead of "if (value)" consistently.
+ Changed ZlibSrcDir from 1.2.5 to 1.2.8 in projects/vstudio.
+ Moved configuration information from the manual to the INSTALL file.
+
+Version 1.6.11beta02 [April 6, 2014]
+ Removed #if/#else/#endif from inside two pow() calls in pngvalid.c because
+ they were handled improperly by Portland Group's PGI-14.1 - PGI-14.3
+ when using its "__builtin_pow()" function.
+ Silence 'unused parameter' build warnings (Cosmin Truta).
+ $(CP) is now used alongside $(RM_F). Also, use 'copy' instead of 'cp'
+ where applicable, and applied other minor makefile changes (Cosmin).
+ Don't warn about invalid dimensions exceeding user limits (Cosmin).
+ Allow an easy replacement of the default pre-built configuration
+ header with a custom header, via the make PNGLIBCONF_H_PREBUILT
+ macro (Cosmin).
+
+Version 1.6.11beta03 [April 6, 2014]
+ Fixed a typo in pngrutil.c, introduced in libpng-1.5.6, that interferes
+ with "blocky" expansion of sub-8-bit interlaced PNG files (Eric Huss).
+ Optionally use __builtin_bswap16() in png_do_swap().
+
+Version 1.6.11beta04 [April 19, 2014]
+ Made progressive reading of interlaced images consistent with the
+ behavior of the sequential reader and consistent with the manual, by
+ moving some code out of the PNG_READ_INTERLACING_SUPPORTED blocks. The
+ row_callback now receives the proper pass number and unexpanded rows, when
+ png_combine_row() isn't built or used, and png_set_interlace_handling()
+ is not called.
+ Allow PNG_sRGB_PROFILE_CHECKING = (-1) to mean no sRGB profile checking.
+
+Version 1.6.11beta05 [April 26, 2014]
+ Do not reject ICC V2 profiles that lack padding (Kai-Uwe Behrmann).
+ Relocated closing bracket of the sRGB profile test loop to avoid getting
+ "Not recognizing known sRGB profile that has been edited" warning for
+ ICC V2 profiles that lack the MD5 signature in the profile header.
+
+Version 1.6.11beta06 [May 19, 2014]
+ Added PNG_SKIP_sRGB_CHECK_PROFILE choice for png_set_option().
+
+Version 1.6.11rc01 [May 27, 2014]
+ No changes.
+
+Version 1.6.11rc02 [June 3, 2014]
+ Test ZLIB_VERNUM instead of PNG_ZLIB_VERNUM in contrib/tools/pngfix.c
+
+Version 1.6.11 [June 5, 2014]
+ No changes.
+
+Version 1.6.12rc01 [June 6, 2014]
+ Relocated new code from 1.6.11beta06 in png.c to a point after the
+ declarations (Max Stepin).
+
+Version 1.6.12rc02 [June 7, 2014]
+ Changed file permissions of contrib/tools/intgamma.sh,
+ test-driver, and compile from 0644 to 0755 (Cosmin).
+
+Version 1.6.12rc03 [June 8, 2014]
+ Ensure "__has_attribute()" macro exists before trying to use it with
+ old clang compilers (MacPorts Ticket #43939).
+
+Version 1.6.12 [June 12, 2014]
+ No changes.
+
+Version 1.6.13beta01 [July 4, 2014]
+ Quieted -Wsign-compare and -Wclobber compiler warnings in
+ contrib/pngminus/*.c
+ Added "(void) png_ptr;" where needed in contrib/gregbook to quiet
+ compiler complaints about unused pointers.
+ Split a long output string in contrib/gregbook/rpng2-x.c.
+ Added "PNG_SET_OPTION" requirement for sRGB chunk support to pnglibconf.dfa,
+ Needed for write-only support (John Bowler).
+ Changed "if defined(__ARM_NEON__)" to
+ "if (defined(__ARM_NEON__) || defined(__ARM_NEON))" (James Wu).
+ Fixed clang no-warning builds: png_digit was defined but never used.
+
+Version 1.6.13beta02 [July 21, 2014]
+ Fixed an incorrect separator ("/" should be "\") in scripts/makefile.vcwin32
+ (bug report from Wolfgang S. Kechel). Bug was introduced in libpng-1.6.11.
+ Also fixed makefile.bc32, makefile.bor, makefile.msc, makefile.intel, and
+ makefile.tc3 similarly.
+
+Version 1.6.13beta03 [August 3, 2014]
+ Removed scripts/makefile.elf. It has not worked since libpng-1.5.0beta14
+ due to elimination of the PNG_FUNCTION_EXPORT and PNG_DATA_EXPORT
+ definitions from pngconf.h.
+ Ensure that CMakeLists.txt makes the target "lib" directory before making
+ symbolic link into it (SourceForge bug report #226 by Rolf Timmermans).
+
+Version 1.6.13beta04 [August 8, 2014]
+ Added opinion that the ECCN (Export Control Classification Number) for
+ libpng is EAR99 to the README file.
+ Eliminated use of "$<" in makefile explicit rules, when copying
+ $PNGLIBCONF_H_PREBUILT. This does not work on some versions of make;
+ bug introduced in libpng version 1.6.11.
+
+Version 1.6.13rc01 [August 14, 2014]
+ Made "ccopts" agree with "CFLAGS" in scripts/makefile.hp* and makefile.*sunu
+
+Version 1.6.13 [August 21, 2014]
+ No changes.
+
+Version 1.6.14beta01 [September 14, 2014]
+ Guard usage of png_ptr->options with #ifdef PNG_SET_OPTION_SUPPORTED.
+ Do not build contrib/tools/pngfix.c when PNG_SETJMP_NOT_SUPPORTED,
+ to allow "make" to complete without setjmp support (bug report by
+ Claudio Fontana)
+ Add "#include <setjmp.h>" to contrib/tools/pngfix.c (John Bowler)
+
+Version 1.6.14beta02 [September 18, 2014]
+ Use nanosleep() instead of usleep() in contrib/gregbook/rpng2-x.c
+ because usleep() is deprecated.
+ Define usleep() in contrib/gregbook/rpng2-x.c if not already defined
+ in unistd.h and nanosleep() is not available; fixes error introduced
+ in libpng-1.6.13.
+ Disable floating point exception handling in pngvalid.c when
+ PNG_FLOATING_ARITHMETIC is not supported (bug report by "zootus
+ at users.sourceforge.net").
+
+Version 1.6.14beta03 [September 19, 2014]
+ Define FE_DIVBYZERO, FE_INVALID, and FE_OVERFLOW in pngvalid.c if not
+ already defined. Revert floating point exception handling in pngvalid.c
+ to version 1.6.14beta01 behavior.
+
+Version 1.6.14beta04 [September 27, 2014]
+ Fixed incorrect handling of the iTXt compression flag in pngrutil.c
+ (bug report by Shunsaku Hirata). Bug was introduced in libpng-1.6.0.
+
+Version 1.6.14beta05 [October 1, 2014]
+ Added "option READ_iCCP enables READ_COMPRESSED_TEXT" to pnglibconf.dfa
+
+Version 1.6.14beta06 [October 5, 2014]
+ Removed unused "text_len" parameter from private function png_write_zTXt().
+ Conditionally compile some code in png_deflate_claim(), when
+ PNG_WARNINGS_SUPPORTED and PNG_ERROR_TEXT_SUPPORTED are disabled.
+ Replaced repeated code in pngpread.c with PNG_PUSH_SAVE_BUFFER_IF_FULL.
+ Added "chunk iTXt enables TEXT" and "chunk zTXt enables TEXT"
+ to pnglibconf.dfa.
+ Removed "option READ_COMPRESSED_TEXT enables READ_TEXT" from pnglibconf.dfa,
+ to make it possible to configure a libpng that supports iCCP but not TEXT.
+
+Version 1.6.14beta07 [October 7, 2014]
+ Removed "option WRITE_COMPRESSED_TEXT enables WRITE_TEXT" from pnglibconf.dfa
+ Only mark text chunks as written after successfully writing them.
+
+Version 1.6.14rc01 [October 15, 2014]
+ Fixed some typos in comments.
+
+Version 1.6.14rc02 [October 17, 2014]
+ Changed png_convert_to_rfc_1123() to png_convert_to_rfc_1123_buffer()
+ in the manual, to reflect the change made in libpng-1.6.0.
+ Updated README file to explain that direct access to the png_struct
+ and info_struct members has not been permitted since libpng-1.5.0.
+
+Version 1.6.14 [October 23, 2014]
+ No changes.
+
+Version 1.6.15beta01 [October 29, 2014]
+ Changed "if (!x)" to "if (x == 0)" and "if (x)" to "if (x != 0)"
+ Simplified png_free_data().
+ Added missing "ptr = NULL" after some instances of png_free().
+
+Version 1.6.15beta02 [November 1, 2014]
+ Changed remaining "if (!x)" to "if (x == 0)" and "if (x)" to "if (x != 0)"
+
+Version 1.6.15beta03 [November 3, 2014]
+ Added PNG_USE_ARM_NEON configuration flag (Marcin Juszkiewicz).
+
+Version 1.6.15beta04 [November 4, 2014]
+ Removed new PNG_USE_ARM_NEON configuration flag and made a one-line
+ revision to configure.ac to support ARM on aarch64 instead (John Bowler).
+
+Version 1.6.15beta05 [November 5, 2014]
+ Use png_get_libpng_ver(NULL) instead of PNG_LIBPNG_VER_STRING in
+ example.c, pngtest.c, and applications in the contrib directory.
+ Avoid out-of-bounds memory access in png_user_version_check().
+ Simplified and future-proofed png_user_version_check().
+ Fixed GCC unsigned int->float warnings. Various versions of GCC
+ seem to generate warnings when an unsigned value is implicitly
+ converted to double. This is probably a GCC bug but this change
+ avoids the issue by explicitly converting to (int) where safe.
+ Free all allocated memory in pngimage. The file buffer cache was left
+ allocated at the end of the program, harmless but it causes memory
+ leak reports from clang.
+ Fixed array size calculations to avoid warnings. At various points
+ in the code the number of elements in an array is calculated using
+ sizeof. This generates a compile time constant of type (size_t) which
+ is then typically assigned to an (unsigned int) or (int). Some versions
+ of GCC on 64-bit systems warn about the apparent narrowing, even though
+ the same compiler does apparently generate the correct, in-range,
+ numeric constant. This adds appropriate, safe, casts to make the
+ warnings go away.
+
+Version 1.6.15beta06 [November 6, 2014]
+ Reverted use png_get_libpng_ver(NULL) instead of PNG_LIBPNG_VER_STRING
+ in the manual, example.c, pngtest.c, and applications in the contrib
+ directory. It was incorrect advice.
+
+Version 1.6.15beta07 [November 7, 2014]
+ Removed #ifdef PNG_16BIT_SUPPORTED/#endif around png_product2(); it is
+ needed by png_reciprocal2().
+ Added #ifdef PNG_16BIT_SUPPORTED/#endif around png_log16bit() and
+ png_do_swap().
+ Changed all "#endif /* PNG_FEATURE_SUPPORTED */" to "#endif /* FEATURE */"
+
+Version 1.6.15beta08 [November 8, 2014]
+ More housecleaning in *.h
+
+Version 1.6.15rc01 [November 13, 2014]
+
+Version 1.6.15rc02 [November 14, 2014]
+ The macros passed in the command line to Borland make were ignored if
+ similarly-named macros were already defined in makefiles. This behavior
+ is different from POSIX make and other make programs. Surround the
+ macro definitions with ifndef guards (Cosmin).
+
+Version 1.6.15rc03 [November 16, 2014]
+ Added "-D_CRT_SECURE_NO_WARNINGS" to CFLAGS in scripts/makefile.vcwin32.
+ Removed the obsolete $ARCH variable from scripts/makefile.darwin.
+
+Version 1.6.15 [November 20, 2014]
+ No changes.
+
+Version 1.6.16beta01 [December 14, 2014]
+ Added ".align 2" to arm/filter_neon.S to support old GAS assemblers that
+ don't do alignment correctly.
+ Revised Makefile.am and scripts/symbols.dfn to work with MinGW/MSYS
+ (Bob Friesenhahn).
+
+Version 1.6.16beta02 [December 15, 2014]
+ Revised Makefile.am and scripts/*.dfn again to work with MinGW/MSYS;
+ renamed scripts/*.dfn to scripts/*.c (John Bowler).
+
+Version 1.6.16beta03 [December 21, 2014]
+ Quiet a "comparison always true" warning in pngstest.c (John Bowler).
+
+Version 1.6.16rc01 [December 21, 2014]
+ Restored a test on width that was removed from png.c at libpng-1.6.9
+ (Bug report by Alex Eubanks, CVE-2015-0973).
+
+Version 1.6.16rc02 [December 21, 2014]
+ Undid the update to pngrutil.c in 1.6.16rc01.
+
+Version 1.6.16rc03 [December 21, 2014]
+ Fixed an overflow in png_combine_row() with very wide interlaced images
+ (Bug report and fix by John Bowler, CVE-2014-9495).
+
+Version 1.6.16 [December 22, 2014]
+ No changes.
+
+Version 1.6.17beta01 [January 29, 2015]
+ Removed duplicate PNG_SAFE_LIMITS_SUPPORTED handling from pngconf.h
+ Corrected the width limit calculation in png_check_IHDR().
+ Removed user limits from pngfix. Also pass NULL pointers to
+ png_read_row to skip the unnecessary row de-interlace stuff.
+ Added testing of png_set_packing() to pngvalid.c
+ Regenerated configure scripts in the *.tar distributions with libtool-2.4.4
+ Implement previously untested cases of libpng transforms in pngvalid.c
+ Fixed byte order in png_do_read_filler() with 16-bit input. Previously
+ the high and low bytes of the filler, from png_set_filler() or from
+ png_set_add_alpha(), were read in the wrong order.
+ Made the check for out-of-range values in png_set_tRNS() detect
+ values that are exactly 2^bit_depth, and work on 16-bit platforms.
+ Merged some parts of libpng-1.6.17beta01 and libpng-1.7.0beta47.
+ Added #ifndef __COVERITY__ where needed in png.c, pngrutil.c and
+ pngset.c to avoid warnings about dead code.
+ Added "& 0xff" to many instances of expressions that are typecast
+ to (png_byte), to avoid Coverity warnings.
+
+Version 1.6.17beta02 [February 7, 2015]
+ Work around one more Coverity-scan dead-code warning.
+ Do not build png_product2() when it is unused.
+
+Version 1.6.17beta03 [February 17, 2015]
+ Display user limits in the output from pngtest.
+ Eliminated the PNG_SAFE_LIMITS macro and restored the 1-million-column
+ and 1-million-row default limits in pnglibconf.dfa, that can be reset
+ by the user at build time or run time. This provides a more robust
+ defense against DOS and as-yet undiscovered overflows.
+
+Version 1.6.17beta04 [February 21, 2015]
+ Added PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED macro, on by default.
+ Allow user to call png_get_IHDR() with NULL arguments (Reuben Hawkins).
+ Rebuilt configure scripts with automake-1.15 and libtool-2.4.6
+
+Version 1.6.17beta05 [February 25, 2015]
+ Restored compiling of png_reciprocal2 with PNG_NO_16BIT.
+
+Version 1.6.17beta06 [February 27, 2015]
+ Moved png_set_filter() prototype into a PNG_WRITE_SUPPORTED block
+ of png.h.
+ Avoid runtime checks when converting integer to png_byte with
+ Visual Studio (Sergey Kosarevsky)
+
+Version 1.6.17rc01 [March 4, 2015]
+ No changes.
+
+Version 1.6.17rc02 [March 9, 2015]
+ Removed some comments that the configure script did not handle
+ properly from scripts/pnglibconf.dfa and pnglibconf.h.prebuilt.
+ Free the unknown_chunks structure even when it contains no data.
+
+Version 1.6.17rc03 [March 12, 2015]
+ Updated CMakeLists.txt to add OSX framework, change YES/NO to ON/OFF
+ for consistency, and remove some useless tests (Alexey Petruchik).
+
+Version 1.6.17rc04 [March 16, 2015]
+ Remove pnglibconf.h, pnglibconf.c, and pnglibconf.out instead of
+ pnglibconf.* in "make clean" (Cosmin).
+ Fix bug in calculation of maxbits, in png_write_sBIT, introduced
+ in libpng-1.6.17beta01 (John Bowler).
+
+Version 1.6.17rc05 [March 21, 2015]
+ Define PNG_FILTER_* and PNG_FILTER_VALUE_* in png.h even when WRITE
+ is not supported (John Bowler). This fixes an error introduced in
+ libpng-1.6.17beta06.
+ Reverted "& 0xff" additions of version 1.6.17beta01. Libpng passes
+ the Coverity scan without them.
+
+Version 1.6.17rc06 [March 23, 2015]
+ Remove pnglibconf.dfn and pnglibconf.pre with "make clean".
+ Reformatted some "&0xff" instances to "& 0xff".
+ Fixed simplified 8-bit-linear to sRGB alpha. The calculated alpha
+ value was wrong. It's not clear if this affected the final stored
+ value; in the obvious code path the upper and lower 8-bits of the
+ alpha value were identical and the alpha was truncated to 8-bits
+ rather than dividing by 257 (John Bowler).
+
+Version 1.6.17 [March 26, 2015]
+ No changes.
+
+Version 1.6.18beta01 [April 1, 2015]
+ Removed PNG_SET_CHUNK_[CACHE|MALLOC]_LIMIT_SUPPORTED macros. They
+ have been combined with PNG_SET_USER_LIMITS_SUPPORTED (resolves
+ bug report by Andrew Church).
+ Fixed rgb_to_gray checks and added tRNS checks to pngvalid.c. This
+ fixes some arithmetic errors that caused some tests to fail on
+ some 32-bit platforms (Bug reports by Peter Breitenlohner [i686]
+ and Petr Gajdos [i586]).
+
+Version 1.6.18beta02 [April 26, 2015]
+ Suppressed some warnings from the Borland C++ 5.5.1/5.82 compiler
+ (Bug report by Viktor Szakats).
+
+Version 1.6.18beta03 [May 6, 2015]
+ Replaced "unexpected" with an integer (0xabadca11) in pngset.c
+ where a long was expected, to avoid a compiler warning when PNG_DEBUG > 1.
+ Added contrib/examples/simpleover.c, to demonstrate how to handle
+ alpha compositing of multiple images, using the "simplified API"
+ and an example PNG generation tool, contrib/examples/genpng.c
+ (John Bowler).
+
+Version 1.6.18beta04 [May 20, 2015]
+ PNG_RELEASE_BUILD replaces tests where the code depended on the build base
+ type and can be defined on the command line, allowing testing in beta
+ builds (John Bowler).
+ Avoid Coverity issue 80858 (REVERSE NULL) in pngtest.c PNG_DEBUG builds.
+ Avoid a harmless potential integer overflow in png_XYZ_from_xy() (Bug
+ report from Christopher Ferris).
+
+Version 1.6.18beta05 [May 31, 2015]
+ Backport filter selection code from libpng-1.7.0beta51, to combine
+ sub_row, up_row, avg_row, and paeth_row into try_row and tst_row.
+ Changed png_voidcast(), etc., to voidcast(), etc., in contrib/tools/pngfix.c
+ to avoid confusion with the libpng private macros.
+ Fixed old cut&paste bug in the weighted filter selection code in
+ pngwutil.c, introduced in libpng-0.95, March 1997.
+
+Version 1.6.18beta06 [June 1, 2015]
+ Removed WRITE_WEIGHTED_FILTERED code, to save a few kbytes of the
+ compiled library size. It never worked properly and as far as we can
+ tell, no one uses it. The png_set_filter_heuristics() and
+ png_set_filter_heuristics_fixed() APIs are retained but deprecated
+ and do nothing.
+
+Version 1.6.18beta07 [June 6, 2015]
+ Removed non-working progressive reader 'skip' function. This
+ function has apparently never been used. It was implemented
+ to support back-door modification of png_struct in libpng-1.4.x
+ but (because it does nothing and cannot do anything) was apparently
+ never tested (John Bowler).
+ Fixed cexcept.h in which GCC 5 now reports that one of the auto
+ variables in the Try macro needs to be volatile to prevent value
+ being lost over the setjmp (John Bowler).
+ Fixed NO_WRITE_FILTER and -Wconversion build breaks (John Bowler).
+ Fix g++ build breaks (John Bowler).
+ Quieted some Coverity issues in pngfix.c, png-fix-itxt.c, pngvalid.c,
+ pngstest.c, and pngimage.c. Most seem harmless, but png-fix-itxt
+ would only work with iTXt chunks with length 255 or less.
+ Added #ifdef's to contrib/examples programs so people don't try
+ to compile them without the minimum required support enabled
+ (suggested by Flavio Medeiros).
+
+Version 1.6.18beta08 [June 30, 2015]
+ Eliminated the final two Coverity defects (insecure temporary file
+ handling in contrib/libtests/pngstest.c; possible overflow of
+ unsigned char in contrib/tools/png-fix-itxt.c). To use the "secure"
+ file handling, define PNG_USE_MKSTEMP, otherwise "tmpfile()" will
+ be used.
+ Removed some unused WEIGHTED_FILTER macros from png.h and pngstruct.h
+
+Version 1.6.18beta09 [July 5, 2015]
+ Removed some useless typecasts from contrib/tools/png-fix-itxt.c
+ Fixed a new signed-unsigned comparison in pngrtran.c (Max Stepin).
+ Replaced arbitrary use of 'extern' with #define PNG_LINKAGE_*. To
+ preserve API compatibility, the new defines all default to "extern"
+ (requested by Jan Nijtmans).
+
+Version 1.6.18rc01 [July 9, 2015]
+ Belatedly added Mans Rullgard and James Yu to the list of Contributing
+ Authors.
+
+Version 1.6.18rc02 [July 12, 2015]
+ Restored unused FILTER_HEURISTIC macros removed at libpng-1.6.18beta08
+ to png.h to avoid compatibility warnings.
+
+Version 1.6.18rc03 [July 15, 2015]
+ Minor changes to the man page
+
+Version 1.6.18 [July 23, 2015]
+ No changes.
+
+Version 1.6.19beta01 [July 30, 2015]
+ Updated obsolete information about the simplified API macros in the
+ manual pages (Bug report by Arc Riley).
+ Avoid potentially dereferencing NULL info_ptr in png_info_init_3().
+ Rearranged png.h to put the major sections in the same order as
+ in libpng17.
+ Eliminated unused PNG_COST_SHIFT, PNG_WEIGHT_SHIFT, PNG_COST_FACTOR, and
+ PNG_WEIGHT_FACTOR macros.
+ Suppressed some warnings from the Borland C++ 5.5.1/5.82 compiler
+ (Bug report by Viktor Szakats). Several warnings remain and are
+ unavoidable, where we test for overflow.
+ Fixed potential leak of png_pixels in contrib/pngminus/pnm2png.c
+ Fixed uninitialized variable in contrib/gregbook/rpng2-x.c
+
+Version 1.6.19beta02 [August 19, 2015]
+ Moved config.h.in~ from the "libpng_autotools_files" list to the
+ "libpng_autotools_extra" list in autogen.sh because it was causing a
+ false positive for missing files (bug report by Robert C. Seacord).
+ Removed unreachable "break" statements in png.c, pngread.c, and pngrtran.c
+ to suppress clang warnings (Bug report by Viktor Szakats).
+ Fixed some bad links in the man page.
+ Changed "n bit" to "n-bit" in comments.
+ Added signed/unsigned 16-bit safety net. This removes the dubious
+ 0x8000 flag definitions on 16-bit systems. They aren't supported
+ yet the defs *probably* work, however it seems much safer to do this
+ and be advised if anyone, contrary to advice, is building libpng 1.6
+ on a 16-bit system. It also adds back various switch default clauses
+ for GCC; GCC errors out if they are not present (with an appropriately
+ high level of warnings).
+ Safely convert num_bytes to a png_byte in png_set_sig_bytes() (Robert
+ Seacord).
+ Fixed the recently reported 1's complement security issue by replacing
+ the value that is illegal in the PNG spec, in both signed and unsigned
+ values, with 0. Illegal unsigned values (anything greater than or equal
+ to 0x80000000) can still pass through, but since these are not illegal
+ in ANSI-C (unlike 0x80000000 in the signed case) the checking that
+ occurs later can catch them (John Bowler).
+
+Version 1.6.19beta03 [September 26, 2015]
+ Fixed png_save_int_32 when int is not 2's complement (John Bowler).
+ Updated libpng16 with all the recent test changes from libpng17,
+ including changes to pngvalid.c to ensure that the original,
+ distributed, version of contrib/visupng/cexcept.h can be used
+ (John Bowler).
+ pngvalid contains the correction to the use of SAVE/STORE_
+ UNKNOWN_CHUNKS; a bug revealed by changes in libpng 1.7. More
+ tests contain the --strict option to detect warnings and the
+ pngvalid-standard test has been corrected so that it does not
+ turn on progressive-read. There is a separate test which does
+ that. (John Bowler)
+ Also made some signed/unsigned fixes.
+ Make pngstest error limits version specific. Splitting the machine
+ generated error structs out to a file allows the values to be updated
+ without changing pngstest.c itself. Since libpng 1.6 and 1.7 have
+ slightly different error limits this simplifies maintenance. The
+ makepngs.sh script has also been updated to more accurately reflect
+ current problems in libpng 1.7 (John Bowler).
+ Incorporated new test PNG files into make check. tests/pngstest-*
+ are changed so that the new test files are divided into 8 groups by
+ gamma and alpha channel. These tests have considerably better code
+ and pixel-value coverage than contrib/pngsuite; however,coverage is
+ still incomplete (John Bowler).
+ Removed the '--strict' in 1.6 because of the double-gamma-correction
+ warning, updated pngstest-errors.h for the errors detected with the
+ new contrib/testspngs PNG test files (John Bowler).
+
+Version 1.6.19beta04 [October 15, 2015]
+ Worked around rgb-to-gray issues in libpng 1.6. The previous
+ attempts to ignore the errors in the code aren't quite enough to
+ deal with the 'channel selection' encoding added to libpng 1.7; abort.
+ pngvalid.c is changed to drop this encoding in prior versions.
+ Fixed 'pow' macros in pngvalid.c. It is legal for 'pow' to be a
+ macro, therefore the argument list cannot contain preprocessing
+ directives. Make sure pow is a function where this happens. This is
+ a minimal safe fix, the issue only arises in non-performance-critical
+ code (bug report by Curtis Leach, fix by John Bowler).
+ Added sPLT support to pngtest.c
+
+Version 1.6.19rc01 [October 23, 2015]
+ No changes.
+
+Version 1.6.19rc02 [October 31, 2015]
+ Prevent setting or writing over-length PLTE chunk (Cosmin Truta).
+ Silently truncate over-length PLTE chunk while reading.
+ Libpng incorrectly calculated the output rowbytes when the application
+ decreased either the number of channels or the bit depth (or both) in
+ a user transform. This was safe; libpng overallocated buffer space
+ (potentially by quite a lot; up to 4 times the amount required) but,
+ from 1.5.4 on, resulted in a png_error (John Bowler).
+
+Version 1.6.19rc03 [November 3, 2015]
+ Fixed some inconsequential cut-and-paste typos in png_set_cHRM_XYZ_fixed().
+ Clarified COPYRIGHT information to state explicitly that versions
+ are derived from previous versions.
+ Removed much of the long list of previous versions from png.h and
+ libpng.3.
+
+Version 1.6.19rc04 [November 5, 2015]
+ Fixed new bug with CRC error after reading an over-length palette
+ (bug report by Cosmin Truta) (CVE-2015-8126).
+
+Version 1.6.19 [November 12, 2015]
+ Cleaned up coding style in png_handle_PLTE().
+
+Version 1.6.20beta01 [November 20, 2015]
+ Avoid potential pointer overflow/underflow in png_handle_sPLT() and
+ png_handle_pCAL() (Bug report by John Regehr).
+
+Version 1.6.20beta02 [November 23, 2015]
+ Fixed incorrect implementation of png_set_PLTE() that uses png_ptr
+ not info_ptr, that left png_set_PLTE() open to the CVE-2015-8126
+ vulnerability.
+
+Version 1.6.20beta03 [November 24, 2015]
+ Backported tests from libpng-1.7.0beta69.
+
+Version 1.6.20rc01 [November 26, 2015]
+ Fixed an error in handling of bad zlib CMINFO field in pngfix, found by
+ American Fuzzy Lop, reported by Brian Carpenter. inflate() doesn't
+ immediately fault a bad CMINFO field; instead a 'too far back' error
+ happens later (at least some times). pngfix failed to limit CMINFO to
+ the allowed values but then assumed that window_bits was in range,
+ triggering an assert. The bug is mostly harmless; the PNG file cannot
+ be fixed.
+
+Version 1.6.20rc02 [November 29, 2015]
+ In libpng 1.6 zlib initialization was changed to use the window size
+ in the zlib stream, not a fixed value. This causes some invalid images,
+ where CINFO is too large, to display 'correctly' if the rest of the
+ data is valid. This provides a workaround for zlib versions where the
+ error arises (ones that support the API change to use the window size
+ in the stream).
+
+Version 1.6.20 [December 3, 2015]
+ No changes.
+
+Send comments/corrections/commendations to png-mng-implement at lists.sf.net
+(subscription required; visit
+https://lists.sourceforge.net/lists/listinfo/png-mng-implement
+to subscribe)
+or to glennrp at users.sourceforge.net
+
+Glenn R-P
+#endif
diff --git a/libpng/CMakeLists.txt b/libpng/CMakeLists.txt
new file mode 100644
index 0000000..7bc49c5
--- /dev/null
+++ b/libpng/CMakeLists.txt
@@ -0,0 +1,374 @@
+# CMakeLists.txt
+
+# Copyright (C) 2007-2015 Glenn Randers-Pehrson
+
+# This code is released under the libpng license.
+# For conditions of distribution and use, see the disclaimer
+# and license in png.h
+
+cmake_minimum_required(VERSION 2.4.4)
+set(CMAKE_ALLOW_LOOSE_LOOP_CONSTRUCTS true)
+
+set(CMAKE_CONFIGURATION_TYPES "Release;Debug;MinSizeRel;RelWithDebInfo")
+
+project(libpng C)
+enable_testing()
+
+set(PNGLIB_MAJOR 1)
+set(PNGLIB_MINOR 6)
+set(PNGLIB_RELEASE 20)
+set(PNGLIB_NAME libpng${PNGLIB_MAJOR}${PNGLIB_MINOR})
+set(PNGLIB_VERSION ${PNGLIB_MAJOR}.${PNGLIB_MINOR}.${PNGLIB_RELEASE})
+
+# needed packages
+find_package(ZLIB REQUIRED)
+include_directories(${ZLIB_INCLUDE_DIR})
+
+if(NOT WIN32)
+ find_library(M_LIBRARY
+ NAMES m
+ PATHS /usr/lib /usr/local/lib
+ )
+ if(NOT M_LIBRARY)
+ message(STATUS "math lib 'libm' not found; floating point support disabled")
+ endif()
+else()
+ # not needed on windows
+ set(M_LIBRARY "")
+endif()
+
+# COMMAND LINE OPTIONS
+option(PNG_SHARED "Build shared lib" ON)
+option(PNG_STATIC "Build static lib" ON)
+option(PNG_TESTS "Build libpng tests" ON)
+
+# Many more configuration options could be added here
+option(PNG_FRAMEWORK "Build OS X framework" OFF)
+option(PNG_DEBUG "Build with debug output" OFF)
+option(PNGARG "Disable ANSI-C prototypes" OFF)
+
+# SET LIBNAME
+set(PNG_LIB_NAME png${PNGLIB_MAJOR}${PNGLIB_MINOR})
+
+# to distinguish between debug and release lib
+set(CMAKE_DEBUG_POSTFIX "d")
+
+# Use the prebuilt pnglibconf.h file from the scripts folder
+# TODO: fix this by building with awk; without this no cmake build can be
+# configured directly (to do so indirectly use your local awk to build a
+# pnglibconf.h in the build directory.)
+configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/pnglibconf.h.prebuilt
+ ${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h)
+include_directories(${CMAKE_CURRENT_BINARY_DIR})
+
+# OUR SOURCES
+set(libpng_public_hdrs
+ png.h
+ pngconf.h
+ ${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h
+)
+set(libpng_sources
+ ${libpng_public_hdrs}
+ pngdebug.h
+ pnginfo.h
+ pngpriv.h
+ pngstruct.h
+ png.c
+ pngerror.c
+ pngget.c
+ pngmem.c
+ pngpread.c
+ pngread.c
+ pngrio.c
+ pngrtran.c
+ pngrutil.c
+ pngset.c
+ pngtrans.c
+ pngwio.c
+ pngwrite.c
+ pngwtran.c
+ pngwutil.c
+)
+set(pngtest_sources
+ pngtest.c
+)
+set(pngvalid_sources
+ contrib/libtests/pngvalid.c
+)
+set(pngstest_sources
+ contrib/libtests/pngstest.c
+)
+# SOME NEEDED DEFINITIONS
+
+if(MSVC)
+ add_definitions(-D_CRT_SECURE_NO_DEPRECATE)
+endif(MSVC)
+
+if(PNG_DEBUG)
+ add_definitions(-DPNG_DEBUG)
+endif()
+
+# NOW BUILD OUR TARGET
+include_directories(${CMAKE_CURRENT_SOURCE_DIR} ${ZLIB_INCLUDE_DIR})
+
+unset(PNG_LIB_TARGETS)
+
+if(PNG_SHARED)
+ add_library(${PNG_LIB_NAME} SHARED ${libpng_sources})
+ set(PNG_LIB_TARGETS ${PNG_LIB_NAME})
+ if(MSVC)
+ # msvc does not append 'lib' - do it here to have consistent name
+ set_target_properties(${PNG_LIB_NAME} PROPERTIES PREFIX "lib")
+ set_target_properties(${PNG_LIB_NAME} PROPERTIES IMPORT_PREFIX "lib")
+ endif()
+ target_link_libraries(${PNG_LIB_NAME} ${ZLIB_LIBRARY} ${M_LIBRARY})
+endif()
+
+if(PNG_STATIC)
+ # does not work without changing name
+ set(PNG_LIB_NAME_STATIC ${PNG_LIB_NAME}_static)
+ add_library(${PNG_LIB_NAME_STATIC} STATIC ${libpng_sources})
+ list(APPEND PNG_LIB_TARGETS ${PNG_LIB_NAME_STATIC})
+ if(MSVC)
+ # msvc does not append 'lib' - do it here to have consistent name
+ set_target_properties(${PNG_LIB_NAME_STATIC} PROPERTIES PREFIX "lib")
+ endif()
+ target_link_libraries(${PNG_LIB_NAME_STATIC} ${ZLIB_LIBRARY} ${M_LIBRARY})
+endif()
+
+if(PNG_FRAMEWORK)
+ set(PNG_LIB_NAME_FRAMEWORK ${PNG_LIB_NAME}_framework)
+ add_library(${PNG_LIB_NAME_FRAMEWORK} SHARED ${libpng_sources})
+ list(APPEND PNG_LIB_TARGETS ${PNG_LIB_NAME_FRAMEWORK})
+ set_target_properties(${PNG_LIB_NAME_FRAMEWORK} PROPERTIES
+ FRAMEWORK TRUE
+ FRAMEWORK_VERSION ${PNGLIB_VERSION}
+ MACOSX_FRAMEWORK_SHORT_VERSION_STRING ${PNGLIB_MAJOR}.${PNGLIB_MINOR}
+ MACOSX_FRAMEWORK_BUNDLE_VERSION ${PNGLIB_VERSION}
+ MACOSX_FRAMEWORK_IDENTIFIER org.libpng.libpng
+ XCODE_ATTRIBUTE_INSTALL_PATH "@rpath"
+ PUBLIC_HEADER "${libpng_public_hdrs}"
+ OUTPUT_NAME png)
+ target_link_libraries(${PNG_LIB_NAME_FRAMEWORK} ${ZLIB_LIBRARY} ${M_LIBRARY})
+endif()
+
+if(NOT PNG_LIB_TARGETS)
+ message(SEND_ERROR
+ "No library variant selected to build. "
+ "Please enable at least one of the following options: "
+ " PNG_STATIC, PNG_SHARED, PNG_FRAMEWORK")
+endif()
+
+if(PNG_SHARED AND WIN32)
+ set_target_properties(${PNG_LIB_NAME} PROPERTIES DEFINE_SYMBOL PNG_BUILD_DLL)
+endif()
+
+if(PNG_TESTS AND PNG_SHARED)
+ # does not work with msvc due to png_lib_ver issue
+ add_executable(pngtest ${pngtest_sources})
+ target_link_libraries(pngtest ${PNG_LIB_NAME})
+ add_test(pngtest ./pngtest ${CMAKE_CURRENT_SOURCE_DIR}/pngtest.png)
+ #
+ add_executable(pngvalid ${pngvalid_sources})
+ target_link_libraries(pngvalid ${PNG_LIB_NAME})
+ add_test(pngvalid ./pngvalid)
+ add_executable(pngstest ${pngstest_sources})
+ target_link_libraries(pngstest ${PNG_LIB_NAME})
+ add_test(pngstest ./pngstest
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g01.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g02.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g04.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g08.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g16.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn2c08.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn2c16.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn3p01.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn3p02.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn3p04.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn3p08.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn4a08.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn4a16.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn6a08.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn6a16.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn0g01.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn0g02.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn0g04.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn2c16.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn3p08.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbgn2c16.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbgn3p08.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbrn2c08.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbwn0g16.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbwn3p08.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbyn3p08.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftp0n0g08.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftp0n2c08.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftp0n3p08.png
+ ${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftp1n3p08.png
+ )
+endif()
+
+# Ensure the CMAKE_LIBRARY_OUTPUT_DIRECTORY is set
+IF(NOT CMAKE_LIBRARY_OUTPUT_DIRECTORY)
+ SET(CMAKE_LIBRARY_OUTPUT_DIRECTORY "lib")
+ENDIF(NOT CMAKE_LIBRARY_OUTPUT_DIRECTORY)
+
+# Set a variable with CMake code which:
+# Creates a symlink from src to dest (if possible) or alternatively
+# copies if different.
+macro(CREATE_SYMLINK SRC_FILE DEST_FILE)
+ FILE(REMOVE ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${DEST_FILE})
+ if(WIN32 AND NOT CYGWIN AND NOT MSYS)
+ ADD_CUSTOM_COMMAND(
+ OUTPUT ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${DEST_FILE} ${CMAKE_CURRENT_BINARY_DIR}/${DEST_FILE}
+ COMMAND ${CMAKE_COMMAND} -E copy_if_different "${SRC_FILE}" ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${DEST_FILE}
+ COMMAND ${CMAKE_COMMAND} -E copy_if_different "${SRC_FILE}" ${CMAKE_CURRENT_BINARY_DIR}/${DEST_FILE}
+ DEPENDS ${PNG_LIB_TARGETS}
+ )
+ ADD_CUSTOM_TARGET(${DEST_FILE}_COPY ALL DEPENDS ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${DEST_FILE})
+ else(WIN32 AND NOT CYGWIN AND NOT MSYS)
+ get_filename_component(LINK_TARGET "${SRC_FILE}" NAME)
+ execute_process(COMMAND ${CMAKE_COMMAND} -E make_directory ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_LIBRARY_OUTPUT_DIRECTORY})
+ execute_process(COMMAND ${CMAKE_COMMAND} -E create_symlink "${LINK_TARGET}" ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${DEST_FILE} WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+ execute_process(COMMAND ${CMAKE_COMMAND} -E create_symlink "${LINK_TARGET}" ${DEST_FILE} WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
+ endif(WIN32 AND NOT CYGWIN AND NOT MSYS)
+endmacro()
+
+# libpng is a library so default to 'lib'
+if(NOT DEFINED CMAKE_INSTALL_LIBDIR)
+ set(CMAKE_INSTALL_LIBDIR lib)
+endif(NOT DEFINED CMAKE_INSTALL_LIBDIR)
+
+# CREATE PKGCONFIG FILES
+# we use the same files like ./configure, so we have to set its vars
+# Only do this on Windows for Cygwin - the files don't make much sense outside
+# a UNIX look alike
+if(NOT WIN32 OR CYGWIN OR MINGW)
+ set(prefix ${CMAKE_INSTALL_PREFIX})
+ set(exec_prefix ${CMAKE_INSTALL_PREFIX})
+ set(libdir ${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR})
+ set(includedir ${CMAKE_INSTALL_PREFIX}/include)
+ set(LIBS "-lz -lm")
+ configure_file(${CMAKE_CURRENT_SOURCE_DIR}/libpng.pc.in
+ ${CMAKE_CURRENT_BINARY_DIR}/${PNGLIB_NAME}.pc @ONLY)
+ CREATE_SYMLINK(${PNGLIB_NAME}.pc libpng.pc)
+
+ configure_file(${CMAKE_CURRENT_SOURCE_DIR}/libpng-config.in
+ ${CMAKE_CURRENT_BINARY_DIR}/${PNGLIB_NAME}-config @ONLY)
+ CREATE_SYMLINK(${PNGLIB_NAME}-config libpng-config)
+endif(NOT WIN32 OR CYGWIN OR MINGW)
+
+# SET UP LINKS
+if(PNG_SHARED)
+ set_target_properties(${PNG_LIB_NAME} PROPERTIES
+# VERSION 16.${PNGLIB_RELEASE}.1.6.20
+ VERSION 16.${PNGLIB_RELEASE}.0
+ SOVERSION 16
+ CLEAN_DIRECT_OUTPUT 1)
+endif()
+if(PNG_STATIC)
+ # MSVC doesn't use a different file extension for shared vs. static
+ # libs. We are able to change OUTPUT_NAME to remove the _static
+ # for all other platforms.
+ if(NOT MSVC)
+ set_target_properties(${PNG_LIB_NAME_STATIC} PROPERTIES
+ OUTPUT_NAME ${PNG_LIB_NAME}
+ CLEAN_DIRECT_OUTPUT 1)
+ endif()
+endif()
+
+# If CMake > 2.4.x, we set a variable used below to export
+# targets to an export file.
+# TODO: Use VERSION_GREATER after our cmake_minimum_required >= 2.6.2
+if(CMAKE_MAJOR_VERSION GREATER 1 AND CMAKE_MINOR_VERSION GREATER 4)
+ set(PNG_EXPORT_RULE EXPORT libpng)
+elseif(CMAKE_MAJOR_VERSION GREATER 2) # future proof
+ set(PNG_EXPORT_RULE EXPORT libpng)
+endif()
+
+# INSTALL
+if(NOT SKIP_INSTALL_LIBRARIES AND NOT SKIP_INSTALL_ALL )
+ install(TARGETS ${PNG_LIB_TARGETS}
+ ${PNG_EXPORT_RULE}
+ RUNTIME DESTINATION bin
+ LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+ ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
+ FRAMEWORK DESTINATION ${CMAKE_INSTALL_LIBDIR})
+
+ if(PNG_SHARED)
+ # Create a symlink for libpng.dll.a => libpng16.dll.a on Cygwin
+ if(CYGWIN OR MINGW)
+ get_target_property(BUILD_TARGET_LOCATION ${PNG_LIB_NAME} LOCATION_${CMAKE_BUILD_TYPE})
+ CREATE_SYMLINK(${BUILD_TARGET_LOCATION} libpng${CMAKE_IMPORT_LIBRARY_SUFFIX})
+ install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libpng${CMAKE_IMPORT_LIBRARY_SUFFIX}
+ DESTINATION ${CMAKE_INSTALL_LIBDIR})
+ endif(CYGWIN OR MINGW)
+
+ if(NOT WIN32)
+ get_target_property(BUILD_TARGET_LOCATION ${PNG_LIB_NAME} LOCATION_${CMAKE_BUILD_TYPE})
+ CREATE_SYMLINK(${BUILD_TARGET_LOCATION} libpng${CMAKE_SHARED_LIBRARY_SUFFIX})
+ install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libpng${CMAKE_SHARED_LIBRARY_SUFFIX}
+ DESTINATION ${CMAKE_INSTALL_LIBDIR})
+ endif(NOT WIN32)
+ endif(PNG_SHARED)
+
+ if(PNG_STATIC)
+ if(NOT WIN32 OR CYGWIN OR MINGW)
+ get_target_property(BUILD_TARGET_LOCATION ${PNG_LIB_NAME_STATIC} LOCATION_${CMAKE_BUILD_TYPE})
+ CREATE_SYMLINK(${BUILD_TARGET_LOCATION} libpng${CMAKE_STATIC_LIBRARY_SUFFIX})
+ install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libpng${CMAKE_STATIC_LIBRARY_SUFFIX}
+ DESTINATION ${CMAKE_INSTALL_LIBDIR})
+ endif(NOT WIN32 OR CYGWIN OR MINGW)
+ endif()
+endif()
+
+if(NOT SKIP_INSTALL_HEADERS AND NOT SKIP_INSTALL_ALL )
+ install(FILES ${libpng_public_hdrs} DESTINATION include)
+ install(FILES ${libpng_public_hdrs} DESTINATION include/${PNGLIB_NAME})
+endif()
+if(NOT SKIP_INSTALL_EXECUTABLES AND NOT SKIP_INSTALL_ALL )
+ if(NOT WIN32 OR CYGWIN OR MINGW)
+ install(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/libpng-config DESTINATION bin)
+ install(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/${PNGLIB_NAME}-config
+ DESTINATION bin)
+ endif(NOT WIN32 OR CYGWIN OR MINGW)
+endif()
+
+if(NOT SKIP_INSTALL_FILES AND NOT SKIP_INSTALL_ALL )
+ # Install man pages
+ if(NOT PNG_MAN_DIR)
+ set(PNG_MAN_DIR "share/man")
+ endif()
+ install(FILES libpng.3 libpngpf.3 DESTINATION ${PNG_MAN_DIR}/man3)
+ install(FILES png.5 DESTINATION ${PNG_MAN_DIR}/man5)
+ # Install pkg-config files
+ if(NOT WIN32 OR CYGWIN OR MINGW)
+ install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libpng.pc
+ DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
+ install(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/libpng-config
+ DESTINATION bin)
+ install(FILES ${CMAKE_CURRENT_BINARY_DIR}/${PNGLIB_NAME}.pc
+ DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
+ install(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/${PNGLIB_NAME}-config
+ DESTINATION bin)
+ endif(NOT WIN32 OR CYGWIN OR MINGW)
+endif()
+
+# On versions of CMake that support it, create an export file CMake
+# users can include() to import our targets
+if(PNG_EXPORT_RULE AND NOT SKIP_INSTALL_EXPORT AND NOT SKIP_INSTALL_ALL )
+ install(EXPORT libpng DESTINATION lib/libpng FILE lib${PNG_LIB_NAME}.cmake)
+endif()
+
+# what's with libpng-manual.txt and all the extra files?
+
+# UNINSTALL
+# do we need this?
+
+# DIST
+# do we need this?
+
+# to create msvc import lib for mingw compiled shared lib
+# pexports libpng.dll > libpng.def
+# lib /def:libpng.def /machine:x86
+
diff --git a/libpng/CleanSpec.mk b/libpng/CleanSpec.mk
new file mode 100644
index 0000000..b84e1b6
--- /dev/null
+++ b/libpng/CleanSpec.mk
@@ -0,0 +1,49 @@
+# Copyright (C) 2007 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+# If you don't need to do a full clean build but would like to touch
+# a file or delete some intermediate files, add a clean step to the end
+# of the list. These steps will only be run once, if they haven't been
+# run before.
+#
+# E.g.:
+# $(call add-clean-step, touch -c external/sqlite/sqlite3.h)
+# $(call add-clean-step, rm -rf $(PRODUCT_OUT)/obj/STATIC_LIBRARIES/libz_intermediates)
+#
+# Always use "touch -c" and "rm -f" or "rm -rf" to gracefully deal with
+# files that are missing or have been moved.
+#
+# Use $(PRODUCT_OUT) to get to the "out/target/product/blah/" directory.
+# Use $(OUT_DIR) to refer to the "out" directory.
+#
+# If you need to re-do something that's already mentioned, just copy
+# the command and add it to the bottom of the list. E.g., if a change
+# that you made last week required touching a file and a change you
+# made today requires touching the same file, just copy the old
+# touch step and add it to the end of the list.
+#
+# ************************************************
+# NEWER CLEAN STEPS MUST BE AT THE END OF THE LIST
+# ************************************************
+
+# For example:
+#$(call add-clean-step, rm -rf $(OUT_DIR)/target/common/obj/APPS/AndroidTests_intermediates)
+#$(call add-clean-step, rm -rf $(OUT_DIR)/target/common/obj/JAVA_LIBRARIES/core_intermediates)
+#$(call add-clean-step, find $(OUT_DIR) -type f -name "IGTalkSession*" -print0 | xargs -0 rm -f)
+#$(call add-clean-step, rm -rf $(PRODUCT_OUT)/data/*)
+
+# ************************************************
+# NEWER CLEAN STEPS MUST BE AT THE END OF THE LIST
+# ************************************************
diff --git a/libpng/INSTALL b/libpng/INSTALL
new file mode 100644
index 0000000..a294ffe
--- /dev/null
+++ b/libpng/INSTALL
@@ -0,0 +1,407 @@
+
+Installing libpng
+
+Contents
+
+ I. Simple installation
+ II. Rebuilding the configure scripts
+ III. Using scripts/makefile*
+ IV. Using cmake
+ V. Directory structure
+ VI. Building with project files
+ VII. Building with makefiles
+VIII. Configuring libpng for 16-bit platforms
+ IX. Configuring for DOS
+ X. Configuring for Medium Model
+ XI. Prepending a prefix to exported symbols
+ XII. Configuring for compiler xxx:
+XIII. Removing unwanted object code
+ XIV. Changes to the build and configuration of libpng in libpng-1.5.x
+ XV. Setjmp/longjmp issues
+ XVI. Other sources of information about libpng
+
+I. Simple installation
+
+On Unix/Linux and similar systems, you can simply type
+
+ ./configure [--prefix=/path]
+ make check
+ make install
+
+and ignore the rest of this document. "/path" is the path to the directory
+where you want to install the libpng "lib", "include", and "bin"
+subdirectories.
+
+If you downloaded a GIT clone, you will need to run ./autogen.sh before
+running ./configure, to create "configure" and "Makefile.in" which are
+not included in the GIT repository.
+
+Note that "configure" is only included in the "*.tar" distributions and not
+in the "*.zip" or "*.7z" distributions. If you downloaded one of those
+distributions, see "Building with project files" or "Building with makefiles",
+below.
+
+II. Rebuilding the configure scripts
+
+If configure does not work on your system, or if you have a need to
+change configure.ac or Makefile.am, and you have a reasonably
+up-to-date set of tools, running ./autogen.sh in a git clone before
+running ./configure may fix the problem. To be really sure that you
+aren't using any of the included pre-built scripts, you can do this:
+
+ ./configure --enable-maintainer-mode
+ make maintainer-clean
+ ./autogen.sh --maintainer --clean
+ ./autogen.sh --maintainer
+ ./configure [--prefix=/path] [other options]
+ make
+ make install
+ make check
+
+III. Using scripts/makefile*
+
+Instead, you can use one of the custom-built makefiles in the
+"scripts" directory
+
+ cp scripts/pnglibconf.h.prebuilt pnglibconf.h
+ cp scripts/makefile.system makefile
+ make test
+ make install
+
+The files that are presently available in the scripts directory
+are listed and described in scripts/README.txt.
+
+Or you can use one of the "projects" in the "projects" directory.
+
+Before installing libpng, you must first install zlib, if it
+is not already on your system. zlib can usually be found
+wherever you got libpng; otherwise go to http://zlib.net. You can place
+zlib in in the same directory as libpng or in another directory.
+
+If your system already has a preinstalled zlib you will still need
+to have access to the zlib.h and zconf.h include files that
+correspond to the version of zlib that's installed.
+
+If you wish to test with a particular zlib that is not first in the
+standard library search path, put ZLIBLIB, ZLIBINC, CPPFLAGS, LDFLAGS,
+and LD_LIBRARY_PATH in your environment before running "make test"
+or "make distcheck":
+
+ZLIBLIB=/path/to/lib export ZLIBLIB
+ZLIBINC=/path/to/include export ZLIBINC
+CPPFLAGS="-I$ZLIBINC" export CPPFLAGS
+LDFLAGS="-L$ZLIBLIB" export LDFLAGS
+LD_LIBRARY_PATH="$ZLIBLIB:$LD_LIBRARY_PATH" export LD_LIBRARY_PATH
+
+If you are using one of the makefile scripts, put ZLIBLIB and ZLIBINC
+in your environment and type "make ZLIBLIB=$ZLIBLIB ZLIBINC=$ZLIBINC test".
+
+IV. Using cmake
+
+If you want to use "cmake" (see www.cmake.org), type
+
+ cmake . -DCMAKE_INSTALL_PREFIX=/path
+ make
+ make install
+
+As when using the simple configure method described above, "/path" points to
+the installation directory where you want to put the libpng "lib", "include",
+and "bin" subdirectories.
+
+V. Directory structure
+
+You can rename the directories that you downloaded (they
+might be called "libpng-x.y.z" or "libpngNN" and "zlib-1.2.8"
+or "zlib128") so that you have directories called "zlib" and "libpng".
+
+Your directory structure should look like this:
+
+ .. (the parent directory)
+ libpng (this directory)
+ INSTALL (this file)
+ README
+ *.h, *.c => libpng source files
+ CMakeLists.txt => "cmake" script
+ configuration files:
+ configure.ac, configure, Makefile.am, Makefile.in,
+ autogen.sh, config.guess, ltmain.sh, missing, libpng.pc.in,
+ libpng-config.in, aclocal.m4, config.h.in, config.sub,
+ depcomp, install-sh, mkinstalldirs, test-pngtest.sh
+ contrib
+ arm-neon, conftest, examples, gregbook, libtests, pngminim,
+ pngminus, pngsuite, tools, visupng
+ projects
+ cbuilder5, owatcom, visualc71, vstudio, xcode
+ scripts
+ makefile.*
+ *.def (module definition files)
+ etc.
+ pngtest.png
+ etc.
+ zlib
+ README, *.h, *.c contrib, etc.
+
+If the line endings in the files look funny, you may wish to get the other
+distribution of libpng. It is available in both tar.gz (UNIX style line
+endings) and zip (DOS style line endings) formats.
+
+VI. Building with project files
+
+If you are building libpng with MSVC, you can enter the
+libpng projects\visualc71 or vstudio directory and follow the instructions
+in README.txt.
+
+Otherwise enter the zlib directory and follow the instructions in zlib/README,
+then come back here and run "configure" or choose the appropriate
+makefile.sys in the scripts directory.
+
+VII. Building with makefiles
+
+Copy the file (or files) that you need from the
+scripts directory into this directory, for example
+
+ MSDOS example: copy scripts\makefile.msc makefile
+ copy scripts\pnglibconf.h.prebuilt pnglibconf.h
+ UNIX example: cp scripts/makefile.std makefile
+ cp scripts/pnglibconf.h.prebuilt pnglibconf.h
+
+Read the makefile to see if you need to change any source or
+target directories to match your preferences.
+
+Then read pnglibconf.dfa to see if you want to make any configuration
+changes.
+
+Then just run "make" which will create the libpng library in
+this directory and "make test" which will run a quick test that reads
+the "pngtest.png" file and writes a "pngout.png" file that should be
+identical to it. Look for "9782 zero samples" in the output of the
+test. For more confidence, you can run another test by typing
+"pngtest pngnow.png" and looking for "289 zero samples" in the output.
+Also, you can run "pngtest -m contrib/pngsuite/*.png" and compare
+your output with the result shown in contrib/pngsuite/README.
+
+Most of the makefiles will allow you to run "make install" to
+put the library in its final resting place (if you want to
+do that, run "make install" in the zlib directory first if necessary).
+Some also allow you to run "make test-installed" after you have
+run "make install".
+
+VIII. Configuring libpng for 16-bit platforms
+
+You will want to look into zconf.h to tell zlib (and thus libpng) that
+it cannot allocate more than 64K at a time. Even if you can, the memory
+won't be accessible. So limit zlib and libpng to 64K by defining MAXSEG_64K.
+
+IX. Configuring for DOS
+
+For DOS users who only have access to the lower 640K, you will
+have to limit zlib's memory usage via a png_set_compression_mem_level()
+call. See zlib.h or zconf.h in the zlib library for more information.
+
+X. Configuring for Medium Model
+
+Libpng's support for medium model has been tested on most of the popular
+compilers. Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets
+defined, and FAR gets defined to far in pngconf.h, and you should be
+all set. Everything in the library (except for zlib's structure) is
+expecting far data. You must use the typedefs with the p or pp on
+the end for pointers (or at least look at them and be careful). Make
+note that the rows of data are defined as png_bytepp, which is
+an "unsigned char far * far *".
+
+XI. Prepending a prefix to exported symbols
+
+Starting with libpng-1.6.0, you can configure libpng (when using the
+"configure" script) to prefix all exported symbols by means of the
+configuration option "--with-libpng-prefix=FOO_", where FOO_ can be any
+string beginning with a letter and containing only uppercase
+and lowercase letters, digits, and the underscore (i.e., a C language
+identifier). This creates a set of macros in pnglibconf.h, so this is
+transparent to applications; their function calls get transformed by
+the macros to use the modified names.
+
+XII. Configuring for compiler xxx:
+
+All includes for libpng are in pngconf.h. If you need to add, change
+or delete an include, this is the place to do it.
+The includes that are not needed outside libpng are placed in pngpriv.h,
+which is only used by the routines inside libpng itself.
+The files in libpng proper only include pngpriv.h and png.h, which
+in turn includes pngconf.h and, as of libpng-1.5.0, pnglibconf.h.
+As of libpng-1.5.0, pngpriv.h also includes three other private header
+files, pngstruct.h, pnginfo.h, and pngdebug.h, which contain material
+that previously appeared in the public headers.
+
+XIII. Removing unwanted object code
+
+There are a bunch of #define's in pngconf.h that control what parts of
+libpng are compiled. All the defines end in _SUPPORTED. If you are
+never going to use a capability, you can change the #define to #undef
+before recompiling libpng and save yourself code and data space, or
+you can turn off individual capabilities with defines that begin with
+PNG_NO_.
+
+In libpng-1.5.0 and later, the #define's are in pnglibconf.h instead.
+
+You can also turn all of the transforms and ancillary chunk capabilities
+off en masse with compiler directives that define
+PNG_NO_READ[or WRITE]_TRANSFORMS, or PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS,
+or all four, along with directives to turn on any of the capabilities that
+you do want. The PNG_NO_READ[or WRITE]_TRANSFORMS directives disable the
+extra transformations but still leave the library fully capable of reading
+and writing PNG files with all known public chunks. Use of the
+PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS directive produces a library
+that is incapable of reading or writing ancillary chunks. If you are
+not using the progressive reading capability, you can turn that off
+with PNG_NO_PROGRESSIVE_READ (don't confuse this with the INTERLACING
+capability, which you'll still have).
+
+All the reading and writing specific code are in separate files, so the
+linker should only grab the files it needs. However, if you want to
+make sure, or if you are building a stand alone library, all the
+reading files start with "pngr" and all the writing files start with "pngw".
+The files that don't match either (like png.c, pngtrans.c, etc.)
+are used for both reading and writing, and always need to be included.
+The progressive reader is in pngpread.c
+
+If you are creating or distributing a dynamically linked library (a .so
+or DLL file), you should not remove or disable any parts of the library,
+as this will cause applications linked with different versions of the
+library to fail if they call functions not available in your library.
+The size of the library itself should not be an issue, because only
+those sections that are actually used will be loaded into memory.
+
+XIV. Changes to the build and configuration of libpng in libpng-1.5.x
+
+Details of internal changes to the library code can be found in the CHANGES
+file and in the GIT repository logs. These will be of no concern to the vast
+majority of library users or builders; however, the few who configure libpng
+to a non-default feature set may need to change how this is done.
+
+There should be no need for library builders to alter build scripts if
+these use the distributed build support - configure or the makefiles -
+however, users of the makefiles may care to update their build scripts
+to build pnglibconf.h where the corresponding makefile does not do so.
+
+Building libpng with a non-default configuration has changed completely.
+The old method using pngusr.h should still work correctly even though the
+way pngusr.h is used in the build has been changed; however, library
+builders will probably want to examine the changes to take advantage of
+new capabilities and to simplify their build system.
+
+A. Specific changes to library configuration capabilities
+
+The exact mechanism used to control attributes of API functions has
+changed. A single set of operating system independent macro definitions
+is used and operating system specific directives are defined in
+pnglibconf.h
+
+As part of this the mechanism used to choose procedure call standards on
+those systems that allow a choice has been changed. At present this only
+affects certain Microsoft (DOS, Windows) and IBM (OS/2) operating systems
+running on Intel processors. As before, PNGAPI is defined where required
+to control the exported API functions; however, two new macros, PNGCBAPI
+and PNGCAPI, are used instead for callback functions (PNGCBAPI) and
+(PNGCAPI) for functions that must match a C library prototype (currently
+only png_longjmp_ptr, which must match the C longjmp function.) The new
+approach is documented in pngconf.h
+
+Despite these changes, libpng 1.5.0 only supports the native C function
+calling standard on those platforms tested so far (__cdecl on Microsoft
+Windows). This is because the support requirements for alternative
+calling conventions seem to no longer exist. Developers who find it
+necessary to set PNG_API_RULE to 1 should advise the mailing list
+(png-mng-implement) of this and library builders who use Openwatcom and
+therefore set PNG_API_RULE to 2 should also contact the mailing list.
+
+B. Changes to the configuration mechanism
+
+Prior to libpng-1.5.0 library builders who needed to configure libpng
+had either to modify the exported pngconf.h header file to add system
+specific configuration or had to write feature selection macros into
+pngusr.h and cause this to be included into pngconf.h by defining
+PNG_USER_CONFIG. The latter mechanism had the disadvantage that an
+application built without PNG_USER_CONFIG defined would see the
+unmodified, default, libpng API and thus would probably fail to link.
+
+These mechanisms still work in the configure build and in any makefile
+build that builds pnglibconf.h, although the feature selection macros
+have changed somewhat as described above. In 1.5.0, however, pngusr.h is
+processed only once, at the time the exported header file pnglibconf.h is
+built. pngconf.h no longer includes pngusr.h; therefore, pngusr.h is ignored
+after the build of pnglibconf.h and it is never included in an application
+build.
+
+The formerly used alternative of adding a list of feature macros to the
+CPPFLAGS setting in the build also still works; however, the macros will be
+copied to pnglibconf.h and this may produce macro redefinition warnings
+when the individual C files are compiled.
+
+All configuration now only works if pnglibconf.h is built from
+scripts/pnglibconf.dfa. This requires the program awk. Brian Kernighan
+(the original author of awk) maintains C source code of that awk and this
+and all known later implementations (often called by subtly different
+names - nawk and gawk for example) are adequate to build pnglibconf.h.
+The Sun Microsystems (now Oracle) program 'awk' is an earlier version
+and does not work; this may also apply to other systems that have a
+functioning awk called 'nawk'.
+
+Configuration options are now documented in scripts/pnglibconf.dfa. This
+file also includes dependency information that ensures a configuration is
+consistent; that is, if a feature is switched off, dependent features are
+also switched off. As a recommended alternative to using feature macros in
+pngusr.h a system builder may also define equivalent options in pngusr.dfa
+(or, indeed, any file) and add that to the configuration by setting
+DFA_XTRA to the file name. The makefiles in contrib/pngminim illustrate
+how to do this, and also illustrate a case where pngusr.h is still required.
+
+After you have built libpng, the definitions that were recorded in
+pnglibconf.h are available to your application (pnglibconf.h is included
+in png.h and gets installed alongside png.h and pngconf.h in your
+$PREFIX/include directory). Do not edit pnglibconf.h after you have built
+libpng, because than the settings would not accurately reflect the settings
+that were used to build libpng.
+
+XV. Setjmp/longjmp issues
+
+Libpng uses setjmp()/longjmp() for error handling. Unfortunately setjmp()
+is known to be not thread-safe on some platforms and we don't know of
+any platform where it is guaranteed to be thread-safe. Therefore, if
+your application is going to be using multiple threads, you should
+configure libpng with PNG_NO_SETJMP in your pngusr.dfa file, with
+-DPNG_NO_SETJMP on your compile line, or with
+
+ #undef PNG_SETJMP_SUPPORTED
+
+in your pnglibconf.h or pngusr.h.
+
+Starting with libpng-1.6.0, the library included a "simplified API".
+This requires setjmp/longjmp, so you must either build the library
+with PNG_SETJMP_SUPPORTED defined, or with PNG_SIMPLIFIED_READ_SUPPORTED
+and PNG_SIMPLIFIED_WRITE_SUPPORTED undefined.
+
+XVI. Other sources of information about libpng:
+
+Further information can be found in the README and libpng-manual.txt
+files, in the individual makefiles, in png.h, and the manual pages
+libpng.3 and png.5.
+
+Using the ./configure script -- 16 December 2002.
+=================================================
+
+The ./configure script should work compatibly with what scripts/makefile.*
+did, however there are some options you might need to add to configure
+explicitly, which previously was done semi-automatically (if you didn't edit
+scripts/makefile.* yourself, that is)
+
+CFLAGS="-Wall -O -funroll-loops \
+-malign-loops=2 -malign-functions=2" ./configure --prefix=/usr/include \
+--with-pkgconfigdir=/usr/lib/pkgconfig --includedir=/usr/include
+
+You can alternatively specify --includedir=/usr/include, /usr/local/include,
+/usr/include/libpng16, or whatever.
+
+If you find that the configure script is out-of-date or is not supporting
+your platform properly, try running autogen.sh to regenerate "configure",
+"Makefile.in", and the other configuration files. Then try configure again.
+
diff --git a/libpng/LICENSE b/libpng/LICENSE
new file mode 100644
index 0000000..82dbe11
--- /dev/null
+++ b/libpng/LICENSE
@@ -0,0 +1,112 @@
+
+This copy of the libpng notices is provided for your convenience. In case of
+any discrepancy between this copy and the notices in the file png.h that is
+included in the libpng distribution, the latter shall prevail.
+
+COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
+
+If you modify libpng you may insert additional notices immediately following
+this sentence.
+
+This code is released under the libpng license.
+
+libpng versions 1.0.7, July 1, 2000, through 1.6.20, December 3, 2015, are
+Copyright (c) 2000-2002, 2004, 2006-2015 Glenn Randers-Pehrson, are
+derived from libpng-1.0.6, and are distributed according to the same
+disclaimer and license as libpng-1.0.6 with the following individuals
+added to the list of Contributing Authors:
+
+ Simon-Pierre Cadieux
+ Eric S. Raymond
+ Mans Rullgard
+ Cosmin Truta
+ Gilles Vollant
+ James Yu
+
+and with the following additions to the disclaimer:
+
+ There is no warranty against interference with your enjoyment of the
+ library or against infringement. There is no warranty that our
+ efforts or the library will fulfill any of your particular purposes
+ or needs. This library is provided with all faults, and the entire
+ risk of satisfactory quality, performance, accuracy, and effort is with
+ the user.
+
+libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
+Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
+libpng-0.96, and are distributed according to the same disclaimer and
+license as libpng-0.96, with the following individuals added to the list
+of Contributing Authors:
+
+ Tom Lane
+ Glenn Randers-Pehrson
+ Willem van Schaik
+
+libpng versions 0.89, June 1996, through 0.96, May 1997, are
+Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,
+and are distributed according to the same disclaimer and license as
+libpng-0.88, with the following individuals added to the list of
+Contributing Authors:
+
+ John Bowler
+ Kevin Bracey
+ Sam Bushell
+ Magnus Holmgren
+ Greg Roelofs
+ Tom Tanner
+
+libpng versions 0.5, May 1995, through 0.88, January 1996, are
+Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
+
+For the purposes of this copyright and license, "Contributing Authors"
+is defined as the following set of individuals:
+
+ Andreas Dilger
+ Dave Martindale
+ Guy Eric Schalnat
+ Paul Schmidt
+ Tim Wegner
+
+The PNG Reference Library is supplied "AS IS". The Contributing Authors
+and Group 42, Inc. disclaim all warranties, expressed or implied,
+including, without limitation, the warranties of merchantability and of
+fitness for any purpose. The Contributing Authors and Group 42, Inc.
+assume no liability for direct, indirect, incidental, special, exemplary,
+or consequential damages, which may result from the use of the PNG
+Reference Library, even if advised of the possibility of such damage.
+
+Permission is hereby granted to use, copy, modify, and distribute this
+source code, or portions hereof, for any purpose, without fee, subject
+to the following restrictions:
+
+ 1. The origin of this source code must not be misrepresented.
+
+ 2. Altered versions must be plainly marked as such and must not
+ be misrepresented as being the original source.
+
+ 3. This Copyright notice may not be removed or altered from any
+ source or altered source distribution.
+
+The Contributing Authors and Group 42, Inc. specifically permit, without
+fee, and encourage the use of this source code as a component to
+supporting the PNG file format in commercial products. If you use this
+source code in a product, acknowledgment is not required but would be
+appreciated.
+
+END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.
+
+A "png_get_copyright" function is available, for convenient use in "about"
+boxes and the like:
+
+ printf("%s", png_get_copyright(NULL));
+
+Also, the PNG logo (in PNG format, of course) is supplied in the
+files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
+
+Libpng is OSI Certified Open Source Software. OSI Certified Open Source is
+a certification mark of the Open Source Initiative. OSI has not addressed
+the additional disclaimers inserted at version 1.0.7.
+
+Glenn Randers-Pehrson
+glennrp at users.sourceforge.net
+December 3, 2015
diff --git a/libpng/MODULE_LICENSE_BSD_LIKE b/libpng/MODULE_LICENSE_BSD_LIKE
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/libpng/MODULE_LICENSE_BSD_LIKE
diff --git a/libpng/Makefile.am b/libpng/Makefile.am
new file mode 100644
index 0000000..73097db
--- /dev/null
+++ b/libpng/Makefile.am
@@ -0,0 +1,361 @@
+# Makefile.am:
+# Source file for Makefile.in (and hence Makefile)
+#
+
+PNGLIB_BASENAME= libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@
+
+ACLOCAL_AMFLAGS = -I scripts
+
+# test programs - run on make check, make distcheck
+check_PROGRAMS= pngtest pngunknown pngstest pngvalid pngimage
+
+# Utilities - installed
+bin_PROGRAMS= pngfix png-fix-itxt
+
+# This ensures that pnglibconf.h gets built at the start of 'make all' or
+# 'make check', but it does not add dependencies to the individual programs,
+# this is done below.
+#
+# IMPORTANT: always add the object modules of new programs to the list below
+# because otherwise the sequence 'configure; make new-program' will *sometimes*
+# result in the installed (system) pnglibconf.h being used and the result is
+# always wrong and always very confusing.
+BUILT_SOURCES = pnglibconf.h
+
+pngtest_SOURCES = pngtest.c
+pngtest_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
+
+pngvalid_SOURCES = contrib/libtests/pngvalid.c
+pngvalid_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
+
+pngstest_SOURCES = contrib/libtests/pngstest.c
+pngstest_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
+
+pngunknown_SOURCES = contrib/libtests/pngunknown.c
+pngunknown_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
+
+pngimage_SOURCES = contrib/libtests/pngimage.c
+pngimage_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
+
+pngfix_SOURCES = contrib/tools/pngfix.c
+pngfix_LDADD = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
+
+png_fix_itxt_SOURCES = contrib/tools/png-fix-itxt.c
+
+# Generally these are single line shell scripts to run a test with a particular
+# set of parameters:
+TESTS =\
+ tests/pngtest\
+ tests/pngvalid-gamma-16-to-8 tests/pngvalid-gamma-alpha-mode\
+ tests/pngvalid-gamma-background tests/pngvalid-gamma-expand16-alpha-mode\
+ tests/pngvalid-gamma-expand16-background\
+ tests/pngvalid-gamma-expand16-transform tests/pngvalid-gamma-sbit\
+ tests/pngvalid-gamma-threshold tests/pngvalid-gamma-transform\
+ tests/pngvalid-progressive-size\
+ tests/pngvalid-progressive-interlace-standard\
+ tests/pngvalid-transform\
+ tests/pngvalid-progressive-standard tests/pngvalid-standard\
+ tests/pngstest-1.8 tests/pngstest-1.8-alpha tests/pngstest-linear\
+ tests/pngstest-linear-alpha tests/pngstest-none tests/pngstest-none-alpha\
+ tests/pngstest-sRGB tests/pngstest-sRGB-alpha tests/pngunknown-IDAT\
+ tests/pngunknown-discard tests/pngunknown-if-safe tests/pngunknown-sAPI\
+ tests/pngunknown-sTER tests/pngunknown-save tests/pngunknown-vpAg\
+ tests/pngimage-quick tests/pngimage-full
+
+# man pages
+dist_man_MANS= libpng.3 libpngpf.3 png.5
+
+# generate the -config scripts if required
+binconfigs= libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@-config
+EXTRA_SCRIPTS= libpng-config libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@-config
+bin_SCRIPTS= @binconfigs@
+
+# rules to build libpng, only build the old library on request
+lib_LTLIBRARIES=libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.la
+# EXTRA_LTLIBRARIES= libpng.la
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES = png.c pngerror.c\
+ pngget.c pngmem.c pngpread.c pngread.c pngrio.c pngrtran.c pngrutil.c\
+ pngset.c pngtrans.c pngwio.c pngwrite.c pngwtran.c pngwutil.c\
+ png.h pngconf.h pngdebug.h pnginfo.h pngpriv.h pngstruct.h pngusr.dfa
+
+if PNG_ARM_NEON
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += arm/arm_init.c\
+ arm/filter_neon.S arm/filter_neon_intrinsics.c
+endif
+
+nodist_libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES = pnglibconf.h
+
+libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LDFLAGS = -no-undefined -export-dynamic \
+ -version-number @PNGLIB_MAJOR@@PNGLIB_MINOR@:@PNGLIB_RELEASE@:0
+
+if HAVE_LD_VERSION_SCRIPT
+# Versioned symbols and restricted exports
+if HAVE_SOLARIS_LD
+ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LDFLAGS += -Wl,-M -Wl,libpng.vers
+else
+ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LDFLAGS += -Wl,--version-script=libpng.vers
+endif
+
+ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_DEPENDENCIES = libpng.vers
+else
+# Only restricted exports when possible
+ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_LDFLAGS += -export-symbols libpng.sym
+ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_DEPENDENCIES = libpng.sym
+endif
+
+#distribute headers in /usr/include/libpng/*
+pkgincludedir= $(includedir)/$(PNGLIB_BASENAME)
+pkginclude_HEADERS= png.h pngconf.h
+nodist_pkginclude_HEADERS= pnglibconf.h
+
+# pkg-config stuff, note that libpng.pc is always required in order
+# to get the correct library
+pkgconfigdir = @pkgconfigdir@
+pkgconfig_DATA = libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.pc
+
+# Extra source distribution files, '${srcdir}' is used below to stop build files
+# from those directories being included. This only works if the configure is
+# not done in the source directory!
+EXTRA_DIST= \
+ ANNOUNCE CHANGES INSTALL LICENSE README TODO \
+ pngtest.png pngbar.png pngnow.png pngbar.jpg autogen.sh \
+ ${srcdir}/contrib ${srcdir}/projects ${srcdir}/scripts \
+ $(TESTS) $(XFAIL_TESTS) tests/pngstest \
+ CMakeLists.txt example.c libpng-manual.txt
+
+SCRIPT_CLEANFILES=scripts/*.out scripts/*.chk
+
+CLEANFILES= *.tf? pngout.png libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.pc \
+ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@-config libpng.vers libpng.sym \
+ check.new pnglibconf.h pngprefix.h symbols.new pngtest-log.txt \
+ pnglibconf.out pnglibconf.c pnglibconf.pre pnglibconf.dfn \
+ $(SCRIPT_CLEANFILES)
+
+MAINTAINERCLEANFILES = Makefile.in aclocal.m4 config.guess config.h.in \
+config.sub configure depcomp install-sh ltmain.sh missing
+
+# PNG_COPTS give extra options for the C compiler to be used on all compilation
+# steps (unless targe_CFLAGS is specified; that will take precedence over
+# AM_CFLAGS)
+PNG_COPTS = @PNG_COPTS@
+AM_CFLAGS = ${PNG_COPTS}
+
+# DFNCPP is normally just CPP - the C preprocessor - but on Solaris and maybe
+# other operating systems (NeXT?) the C preprocessor selected by configure
+# checks input tokens for validity - effectively it performs part of the ANSI-C
+# parsing - and therefore fails with the .df files. configure.ac has special
+# checks for this and sets DFNCPP appropriately.
+DFNCPP = @DFNCPP@
+
+SUFFIXES = .chk .out
+
+$(PNGLIB_BASENAME).pc: libpng.pc
+ cp libpng.pc $@
+
+$(PNGLIB_BASENAME)-config: libpng-config
+ cp libpng-config $@
+
+scripts/sym.out scripts/vers.out: png.h pngconf.h pnglibconf.h
+scripts/prefix.out: png.h pngconf.h pnglibconf.out
+scripts/symbols.out: png.h pngconf.h $(srcdir)/scripts/pnglibconf.h.prebuilt
+scripts/intprefix.out: pnglibconf.h
+
+libpng.sym: scripts/sym.out
+ rm -f $@
+ cp $? $@
+libpng.vers: scripts/vers.out
+ rm -f $@
+ cp $? $@
+
+if DO_PNG_PREFIX
+# Rename functions in scripts/prefix.out with a PNG_PREFIX prefix.
+# Rename macros in scripts/macro.lst from PNG_PREFIXpng_ to PNG_ (the actual
+# implementation of the macro).
+pnglibconf.h: pnglibconf.out scripts/prefix.out scripts/macro.lst
+ rm -f $@
+ $(AWK) 's==0 && NR>1{print prev}\
+ s==0{prev=$$0}\
+ s==1{print "#define", $$1, "@PNG_PREFIX@" $$1}\
+ s==2{print "#define @PNG_PREFIX@png_" $$1, "PNG_" $$1}\
+ END{print prev}' s=0 pnglibconf.out s=1 scripts/prefix.out\
+ s=2 ${srcdir}/scripts/macro.lst >pnglibconf.tf8
+ mv pnglibconf.tf8 $@
+
+pngprefix.h: scripts/intprefix.out
+ rm -f pngprefix.tf1
+ $(AWK) '{print "#define", $$1, "@PNG_PREFIX@" $$1}' $? >pngprefix.tf1
+ mv pngprefix.tf1 $@
+else
+pnglibconf.h: pnglibconf.out
+ rm -f $@
+ cp $? $@
+
+pngprefix.h: # is empty
+ :>$@
+endif
+
+$(srcdir)/scripts/pnglibconf.h.prebuilt:
+ @echo "Attempting to build $@" >&2
+ @echo "This is a machine generated file, but if you want to make" >&2
+ @echo "a new one simply make 'scripts/pnglibconf.out', copy that" >&2
+ @echo "AND set PNG_ZLIB_VERNUM to 0 (you MUST do this)" >&2
+ @exit 1
+
+# The following is necessary to ensure that the local pnglibconf.h is used, not
+# an installed one (this can happen immediately after on a clean system if
+# 'make test' is the first thing the user does.) Only files which include
+# one of the png source files (typically png.h or pngpriv.h) need to be listed
+# here:
+pngtest.o: pnglibconf.h
+
+contrib/libtests/makepng.o: pnglibconf.h
+contrib/libtests/pngstest.o: pnglibconf.h
+contrib/libtests/pngunknown.o: pnglibconf.h
+contrib/libtests/pngimage.o: pnglibconf.h
+contrib/libtests/pngvalid.o: pnglibconf.h
+contrib/libtests/readpng.o: pnglibconf.h
+contrib/libtests/tarith.o: pnglibconf.h
+contrib/libtests/timepng.o: pnglibconf.h
+
+contrib/tools/makesRGB.o: pnglibconf.h
+contrib/tools/pngfix.o: pnglibconf.h
+
+# We must use -DPNG_NO_USE_READ_MACROS here even when the library may actually
+# be built with PNG_USE_READ_MACROS; this prevents the read macros from
+# interfering with the symbol file format.
+SYMBOL_CFLAGS = -DPNGLIB_LIBNAME='PNG@PNGLIB_MAJOR@@PNGLIB_MINOR@_0'\
+ -DPNGLIB_VERSION='@PNGLIB_VERSION@'\
+ -DSYMBOL_PREFIX='$(SYMBOL_PREFIX)'\
+ -DPNG_NO_USE_READ_MACROS -DPNG_BUILDING_SYMBOL_TABLE
+
+if DO_PNG_PREFIX
+SYMBOL_CFLAGS += -DPNG_PREFIX='@PNG_PREFIX@'
+endif
+
+.c.out:
+ rm -f $@ $*.tf[12]
+ test -d scripts || mkdir scripts || test -d scripts
+ $(DFNCPP) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES)\
+ $(CPPFLAGS) $(SYMBOL_CFLAGS) $< > $*.tf1
+ $(AWK) -f "${srcdir}/scripts/dfn.awk" out="$*.tf2" $*.tf1 1>&2
+ rm -f $*.tf1
+ mv $*.tf2 $@
+
+# The .c file for pnglibconf.h is machine generated
+pnglibconf.c: scripts/pnglibconf.dfa scripts/options.awk pngconf.h pngusr.dfa $(DFA_XTRA)
+ rm -f $@ $*.tf[45]
+ $(AWK) -f ${srcdir}/scripts/options.awk out=$*.tf4 version=search\
+ ${srcdir}/pngconf.h ${srcdir}/scripts/pnglibconf.dfa\
+ ${srcdir}/pngusr.dfa $(DFA_XTRA) 1>&2
+ $(AWK) -f ${srcdir}/scripts/options.awk out=$*.tf5 $*.tf4 1>&2
+ rm $*.tf4
+ mv $*.tf5 $@
+
+# Symbol checks (.def and .out files should match)
+scripts/symbols.chk: scripts/checksym.awk scripts/symbols.def scripts/symbols.out
+
+.out.chk:
+ rm -f $@ $*.new
+ $(AWK) -f ${srcdir}/scripts/checksym.awk ${srcdir}/scripts/${*F}.def\
+ of="$*.new" $< >&2
+ mv $*.new $@
+
+# used on demand to regenerate the standard header, CPPFLAGS should
+# be empty - no non-standard defines
+scripts/pnglibconf.c: scripts/pnglibconf.dfa scripts/options.awk pngconf.h
+ rm -f $@ pnglibconf.tf[67]
+ test -z "$(CPPFLAGS)"
+ echo "com @PNGLIB_VERSION@ STANDARD API DEFINITION" |\
+ $(AWK) -f ${srcdir}/scripts/options.awk out=pnglibconf.tf6\
+ logunsupported=1 version=search ${srcdir}/pngconf.h -\
+ ${srcdir}/scripts/pnglibconf.dfa 1>&2
+ $(AWK) -f ${srcdir}/scripts/options.awk out=pnglibconf.tf7\
+ pnglibconf.tf6 1>&2
+ rm pnglibconf.tf6
+ mv pnglibconf.tf7 $@
+
+$(libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_OBJECTS): png.h pngconf.h \
+ pnglibconf.h pngpriv.h pngdebug.h pnginfo.h pngstruct.h pngprefix.h
+
+test: check-am
+
+# Extra checks
+check: scripts/symbols.chk
+
+# Don't distribute the generated script files
+dist-hook:
+ cd '$(top_distdir)'; rm -f $(SCRIPT_CLEANFILES)
+
+# Make links between installed files with release-specific names and the generic
+# file names. If this install rule is run the generic names will be deleted and
+# recreated - this has obvious issues for systems with multiple installations.
+
+install-header-links:
+ @set -ex; cd '$(DESTDIR)$(includedir)'; for f in $(HEADERS); do \
+ rm -f "$$f"; $(LN_S) "$(PNGLIB_BASENAME)/$$f" "$$f"; done
+
+uninstall-header-links:
+ cd '$(DESTDIR)$(includedir)'; rm -f $(HEADERS)
+
+install-libpng-pc:
+ @set -ex; cd '$(DESTDIR)$(pkgconfigdir)'; rm -f libpng.pc; \
+ $(LN_S) '$(PNGLIB_BASENAME).pc' libpng.pc
+
+uninstall-libpng-pc:
+ rm -f '$(DESTDIR)$(pkgconfigdir)/libpng.pc'
+
+# EXT_LIST is a list of the possibly library directory extensions, this exists
+# because we can't find a good way of discovering the file extensions that are
+# actually installed on a given system, so instead we check for every extension
+# we have seen.
+
+EXT_LIST = a dll.a so so.@PNGLIB_MAJOR@@PNGLIB_MINOR@.@PNGLIB_RELEASE@ la sl dylib
+
+install-library-links:
+ @set -x; cd '$(DESTDIR)$(libdir)';\
+ for ext in $(EXT_LIST); do\
+ rm -f "libpng.$$ext";\
+ if test -f "$(PNGLIB_BASENAME).$$ext"; then\
+ $(LN_S) "$(PNGLIB_BASENAME).$$ext" "libpng.$$ext" || exit 1;\
+ fi;\
+ done
+
+uninstall-library-links:
+ @set -x; cd '$(DESTDIR)$(libdir)'; for ext in $(EXT_LIST); do\
+ rm -f "libpng.$$ext"; done
+
+install-libpng-config:
+ @set -ex; cd '$(DESTDIR)$(bindir)'; rm -f libpng-config; \
+ $(LN_S) '$(PNGLIB_BASENAME)-config' libpng-config
+
+uninstall-libpng-config:
+ rm -f '$(DESTDIR)$(bindir)/libpng-config'
+
+if DO_INSTALL_LINKS
+# If --enable-unversioned-links is specified the header and lib file links
+# will be automatically made on a 'make install':
+
+install-data-hook: install-header-links
+uninstall-hook: uninstall-header-links
+install-exec-hook: install-library-links
+uninstall-hook: uninstall-library-links
+endif
+
+if DO_INSTALL_LIBPNG_PC
+# Likewise, --install-pc causes libpng.pc to be constructed:
+
+install-data-hook: install-libpng-pc
+uninstall-hook: uninstall-libpng-pc
+endif
+
+if DO_INSTALL_LIBPNG_CONFIG
+# And --install-config:
+
+install-exec-hook: install-libpng-config
+uninstall-hook: uninstall-libpng-config
+endif
+
+# The following addition ensures that 'make all' always builds the test programs
+# too. It used to, but some change either in libpng or configure stopped this
+# working.
+all-am: $(check_PROGRAMS)
diff --git a/libpng/NOTICE b/libpng/NOTICE
new file mode 100644
index 0000000..11f6ffe
--- /dev/null
+++ b/libpng/NOTICE
@@ -0,0 +1,112 @@
+
+This copy of the libpng notices is provided for your convenience. In case of
+any discrepancy between this copy and the notices in the file png.h that is
+included in the libpng distribution, the latter shall prevail.
+
+COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
+
+If you modify libpng you may insert additional notices immediately following
+this sentence.
+
+This code is released under the libpng license.
+
+libpng versions 1.0.7, July 1, 2000, through 1.6.19, November 12, 2015, are
+Copyright (c) 2000-2002, 2004, 2006-2015 Glenn Randers-Pehrson, are
+derived from libpng-1.0.6, and are distributed according to the same
+disclaimer and license as libpng-1.0.6 with the following individuals
+added to the list of Contributing Authors:
+
+ Simon-Pierre Cadieux
+ Eric S. Raymond
+ Mans Rullgard
+ Cosmin Truta
+ Gilles Vollant
+ James Yu
+
+and with the following additions to the disclaimer:
+
+ There is no warranty against interference with your enjoyment of the
+ library or against infringement. There is no warranty that our
+ efforts or the library will fulfill any of your particular purposes
+ or needs. This library is provided with all faults, and the entire
+ risk of satisfactory quality, performance, accuracy, and effort is with
+ the user.
+
+libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
+Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
+libpng-0.96, and are distributed according to the same disclaimer and
+license as libpng-0.96, with the following individuals added to the list
+of Contributing Authors:
+
+ Tom Lane
+ Glenn Randers-Pehrson
+ Willem van Schaik
+
+libpng versions 0.89, June 1996, through 0.96, May 1997, are
+Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,
+and are distributed according to the same disclaimer and license as
+libpng-0.88, with the following individuals added to the list of
+Contributing Authors:
+
+ John Bowler
+ Kevin Bracey
+ Sam Bushell
+ Magnus Holmgren
+ Greg Roelofs
+ Tom Tanner
+
+libpng versions 0.5, May 1995, through 0.88, January 1996, are
+Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
+
+For the purposes of this copyright and license, "Contributing Authors"
+is defined as the following set of individuals:
+
+ Andreas Dilger
+ Dave Martindale
+ Guy Eric Schalnat
+ Paul Schmidt
+ Tim Wegner
+
+The PNG Reference Library is supplied "AS IS". The Contributing Authors
+and Group 42, Inc. disclaim all warranties, expressed or implied,
+including, without limitation, the warranties of merchantability and of
+fitness for any purpose. The Contributing Authors and Group 42, Inc.
+assume no liability for direct, indirect, incidental, special, exemplary,
+or consequential damages, which may result from the use of the PNG
+Reference Library, even if advised of the possibility of such damage.
+
+Permission is hereby granted to use, copy, modify, and distribute this
+source code, or portions hereof, for any purpose, without fee, subject
+to the following restrictions:
+
+ 1. The origin of this source code must not be misrepresented.
+
+ 2. Altered versions must be plainly marked as such and must not
+ be misrepresented as being the original source.
+
+ 3. This Copyright notice may not be removed or altered from any
+ source or altered source distribution.
+
+The Contributing Authors and Group 42, Inc. specifically permit, without
+fee, and encourage the use of this source code as a component to
+supporting the PNG file format in commercial products. If you use this
+source code in a product, acknowledgment is not required but would be
+appreciated.
+
+END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.
+
+A "png_get_copyright" function is available, for convenient use in "about"
+boxes and the like:
+
+ printf("%s", png_get_copyright(NULL));
+
+Also, the PNG logo (in PNG format, of course) is supplied in the
+files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
+
+Libpng is OSI Certified Open Source Software. OSI Certified Open Source is
+a certification mark of the Open Source Initiative. OSI has not addressed
+the additional disclaimers inserted at version 1.0.7.
+
+Glenn Randers-Pehrson
+glennrp at users.sourceforge.net
+November 12, 2015
diff --git a/libpng/README b/libpng/README
new file mode 100644
index 0000000..59f1f91
--- /dev/null
+++ b/libpng/README
@@ -0,0 +1,215 @@
+README for libpng version 1.6.20 - December 3, 2015 (shared library 16.0)
+See the note about version numbers near the top of png.h
+
+See INSTALL for instructions on how to install libpng.
+
+Libpng comes in several distribution formats. Get libpng-*.tar.gz or
+libpng-*.tar.xz or if you want UNIX-style line endings in the text files,
+or lpng*.7z or lpng*.zip if you want DOS-style line endings.
+
+Version 0.89 was the first official release of libpng. Don't let the
+fact that it's the first release fool you. The libpng library has been in
+extensive use and testing since mid-1995. By late 1997 it had
+finally gotten to the stage where there hadn't been significant
+changes to the API in some time, and people have a bad feeling about
+libraries with versions < 1.0. Version 1.0.0 was released in
+March 1998.
+
+****
+Note that some of the changes to the png_info structure render this
+version of the library binary incompatible with libpng-0.89 or
+earlier versions if you are using a shared library. The type of the
+"filler" parameter for png_set_filler() has changed from png_byte to
+png_uint_32, which will affect shared-library applications that use
+this function.
+
+To avoid problems with changes to the internals of png info_struct,
+new APIs have been made available in 0.95 to avoid direct application
+access to info_ptr. These functions are the png_set_<chunk> and
+png_get_<chunk> functions. These functions should be used when
+accessing/storing the info_struct data, rather than manipulating it
+directly, to avoid such problems in the future.
+
+It is important to note that the APIs did not make current programs
+that access the info struct directly incompatible with the new
+library, through libpng-1.2.x. In libpng-1.4.x, which was meant to
+be a transitional release, members of the png_struct and the
+info_struct can still be accessed, but the compiler will issue a
+warning about deprecated usage. Since libpng-1.5.0, direct access
+to these structs is not allowed, and the definitions of the structs
+reside in private pngstruct.h and pnginfo.h header files that are not
+accessible to applications. It is strongly suggested that new
+programs use the new APIs (as shown in example.c and pngtest.c), and
+older programs be converted to the new format, to facilitate upgrades
+in the future.
+****
+
+Additions since 0.90 include the ability to compile libpng as a
+Windows DLL, and new APIs for accessing data in the info struct.
+Experimental functions include the ability to set weighting and cost
+factors for row filter selection, direct reads of integers from buffers
+on big-endian processors that support misaligned data access, faster
+methods of doing alpha composition, and more accurate 16->8 bit color
+conversion.
+
+The additions since 0.89 include the ability to read from a PNG stream
+which has had some (or all) of the signature bytes read by the calling
+application. This also allows the reading of embedded PNG streams that
+do not have the PNG file signature. As well, it is now possible to set
+the library action on the detection of chunk CRC errors. It is possible
+to set different actions based on whether the CRC error occurred in a
+critical or an ancillary chunk.
+
+The changes made to the library, and bugs fixed are based on discussions
+on the PNG-implement mailing list and not on material submitted
+privately to Guy, Andreas, or Glenn. They will forward any good
+suggestions to the list.
+
+For a detailed description on using libpng, read libpng-manual.txt. For
+examples of libpng in a program, see example.c and pngtest.c. For usage
+information and restrictions (what little they are) on libpng, see
+png.h. For a description on using zlib (the compression library used by
+libpng) and zlib's restrictions, see zlib.h
+
+I have included a general makefile, as well as several machine and
+compiler specific ones, but you may have to modify one for your own needs.
+
+You should use zlib 1.0.4 or later to run this, but it MAY work with
+versions as old as zlib 0.95. Even so, there are bugs in older zlib
+versions which can cause the output of invalid compression streams for
+some images. You will definitely need zlib 1.0.4 or later if you are
+taking advantage of the MS-DOS "far" structure allocation for the small
+and medium memory models. You should also note that zlib is a
+compression library that is useful for more things than just PNG files.
+You can use zlib as a drop-in replacement for fread() and fwrite() if
+you are so inclined.
+
+zlib should be available at the same place that libpng is, or at zlib.net.
+
+You may also want a copy of the PNG specification. It is available
+as an RFC, a W3C Recommendation, and an ISO/IEC Standard. You can find
+these at http://www.libpng.org/pub/png/documents/
+
+This code is currently being archived at libpng.sf.net in the
+[DOWNLOAD] area, and at ftp://ftp.simplesystems.org. If you can't find it
+in any of those places, e-mail me, and I'll help you find it.
+
+I am not a lawyer, but I believe that the Export Control Classification
+Number (ECCN) for libpng is EAR99, which means not subject to export
+controls or International Traffic in Arms Regulations (ITAR) because it
+is open source, publicly available software, that does not contain any
+encryption software. See the EAR, paragraphs 734.3(b)(3) and 734.7(b).
+
+If you have any code changes, requests, problems, etc., please e-mail
+them to me. Also, I'd appreciate any make files or project files,
+and any modifications you needed to make to get libpng to compile,
+along with a #define variable to tell what compiler/system you are on.
+If you needed to add transformations to libpng, or wish libpng would
+provide the image in a different way, drop me a note (and code, if
+possible), so I can consider supporting the transformation.
+Finally, if you get any warning messages when compiling libpng
+(note: not zlib), and they are easy to fix, I'd appreciate the
+fix. Please mention "libpng" somewhere in the subject line. Thanks.
+
+This release was created and will be supported by myself (of course
+based in a large way on Guy's and Andreas' earlier work), and the PNG
+development group.
+
+Send comments/corrections/commendations to png-mng-implement at
+lists.sourceforge.net (subscription required; visit
+https://lists.sourceforge.net/lists/listinfo/png-mng-implement
+to subscribe) or to glennrp at users.sourceforge.net
+
+You can't reach Guy, the original libpng author, at the addresses
+given in previous versions of this document. He and Andreas will
+read mail addressed to the png-implement list, however.
+
+Please do not send general questions about PNG. Send them to
+png-mng-misc at lists.sf.net (subscription required; visit
+https://lists.sourceforge.net/lists/listinfo/png-mng-misc to
+subscribe). If you have a question about something
+in the PNG specification that is related to using libpng, send it
+to me. Send me any questions that start with "I was using libpng,
+and ...". If in doubt, send questions to me. I'll bounce them
+to others, if necessary.
+
+Please do not send suggestions on how to change PNG. We have
+been discussing PNG for twenty years now, and it is official and
+finished. If you have suggestions for libpng, however, I'll
+gladly listen. Even if your suggestion is not used immediately,
+it may be used later.
+
+Files in this distribution:
+
+ ANNOUNCE => Announcement of this version, with recent changes
+ CHANGES => Description of changes between libpng versions
+ KNOWNBUG => List of known bugs and deficiencies
+ LICENSE => License to use and redistribute libpng
+ README => This file
+ TODO => Things not implemented in the current library
+ Y2KINFO => Statement of Y2K compliance
+ example.c => Example code for using libpng functions
+ libpng.3 => manual page for libpng (includes libpng-manual.txt)
+ libpng-manual.txt => Description of libpng and its functions
+ libpngpf.3 => manual page for libpng's private functions
+ png.5 => manual page for the PNG format
+ png.c => Basic interface functions common to library
+ png.h => Library function and interface declarations (public)
+ pngpriv.h => Library function and interface declarations (private)
+ pngconf.h => System specific library configuration (public)
+ pngstruct.h => png_struct declaration (private)
+ pnginfo.h => png_info struct declaration (private)
+ pngdebug.h => debugging macros (private)
+ pngerror.c => Error/warning message I/O functions
+ pngget.c => Functions for retrieving info from struct
+ pngmem.c => Memory handling functions
+ pngbar.png => PNG logo, 88x31
+ pngnow.png => PNG logo, 98x31
+ pngpread.c => Progressive reading functions
+ pngread.c => Read data/helper high-level functions
+ pngrio.c => Lowest-level data read I/O functions
+ pngrtran.c => Read data transformation functions
+ pngrutil.c => Read data utility functions
+ pngset.c => Functions for storing data into the info_struct
+ pngtest.c => Library test program
+ pngtest.png => Library test sample image
+ pngtrans.c => Common data transformation functions
+ pngwio.c => Lowest-level write I/O functions
+ pngwrite.c => High-level write functions
+ pngwtran.c => Write data transformations
+ pngwutil.c => Write utility functions
+ arm => Contains optimized code for the ARM platform
+ contrib => Contributions
+ examples => Example programs
+ gregbook => source code for PNG reading and writing, from
+ Greg Roelofs' "PNG: The Definitive Guide",
+ O'Reilly, 1999
+ libtests => Test programs
+ pngminim => Minimal decoder, encoder, and progressive decoder
+ programs demonstrating use of pngusr.dfa
+ pngminus => Simple pnm2png and png2pnm programs
+ pngsuite => Test images
+ tools => Various tools
+ visupng => Contains a MSVC workspace for VisualPng
+ projects => Contains project files and workspaces for
+ building a DLL
+ owatcom => Contains a WATCOM project for building libpng
+ visualc71 => Contains a Microsoft Visual C++ (MSVC)
+ workspace for building libpng and zlib
+ vstudio => Contains a Microsoft Visual C++ (MSVC)
+ workspace for building libpng and zlib
+ scripts => Directory containing scripts for building libpng:
+ (see scripts/README.txt for the list of scripts)
+
+Good luck, and happy coding.
+
+-Glenn Randers-Pehrson (current maintainer, since 1998)
+ Internet: glennrp at users.sourceforge.net
+
+-Andreas Eric Dilger (former maintainer, 1996-1997)
+ Internet: adilger at enel.ucalgary.ca
+ Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/
+
+-Guy Eric Schalnat (original author and former maintainer, 1995-1996)
+ (formerly of Group 42, Inc)
+ Internet: gschal at infinet.com
diff --git a/libpng/README.android b/libpng/README.android
new file mode 100644
index 0000000..b582ca5
--- /dev/null
+++ b/libpng/README.android
@@ -0,0 +1,19 @@
+Any Android specific modifications to upstream libpng (1.6.20) should
+be listed here:
+
+(1) Android has added the following files.
+ pngusr.h
+ Android.mk
+ CleanSpec.mk
+ MODULE_LICENSE_BSD_LIKE
+ README.version
+
+(2) pnglibconf.h
+ This is copied from scripts/pnglibconf.h.prebuilt.
+ Android has undefined PNG_WARNINGS_SUPPORTED.
+
+(3) Removed contrib/testpngs/
+ There is no reason to check in all of these files if we won't
+ be using them.
+
+(4) PNG_INDEX_SUPPORTED optimizations.
diff --git a/libpng/README.version b/libpng/README.version
new file mode 100644
index 0000000..58890dd
--- /dev/null
+++ b/libpng/README.version
@@ -0,0 +1,3 @@
+URL: http://prdownloads.sourceforge.net/libpng/libpng-1.6.20.tar.gz?download
+Version: 1.6.20
+BugComponent: 87896
diff --git a/libpng/TODO b/libpng/TODO
new file mode 100644
index 0000000..7263377
--- /dev/null
+++ b/libpng/TODO
@@ -0,0 +1,29 @@
+/*
+TODO - list of things to do for libpng:
+
+Final bug fixes.
+Better C++ wrapper/full C++ implementation?
+Fix problem with C++ and EXTERN "C".
+cHRM transformation.
+Remove setjmp/longjmp usage in favor of returning error codes.
+Palette creation.
+Add "grayscale->palette" transformation and "palette->grayscale" detection.
+Improved dithering.
+Multi-lingual error and warning message support.
+Complete sRGB transformation (presently it simply uses gamma=0.45455).
+Make profile checking optional via a png_set_something() call.
+Man pages for function calls.
+Better documentation.
+Better filter selection
+ (counting huffman bits/precompression? filter inertia? filter costs?).
+Histogram creation.
+Text conversion between different code pages (Latin-1 -> Mac and DOS).
+Avoid building gamma tables whenever possible.
+Use greater precision when changing to linear gamma for compositing against
+ background and doing rgb-to-gray transformation.
+Investigate pre-incremented loop counters and other loop constructions.
+Add interpolated method of handling interlacing.
+Switch to the simpler zlib (zlib/libpng) license if legally possible.
+Extend pngvalid.c to validate more of the libpng transformations.
+
+*/
diff --git a/libpng/arm/arm_init.c b/libpng/arm/arm_init.c
new file mode 100644
index 0000000..fb3d50d
--- /dev/null
+++ b/libpng/arm/arm_init.c
@@ -0,0 +1,134 @@
+
+/* arm_init.c - NEON optimised filter functions
+ *
+ * Copyright (c) 2014 Glenn Randers-Pehrson
+ * Written by Mans Rullgard, 2011.
+ * Last changed in libpng 1.6.16 [December 22, 2014]
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ */
+/* Below, after checking __linux__, various non-C90 POSIX 1003.1 functions are
+ * called.
+ */
+#define _POSIX_SOURCE 1
+
+#include "../pngpriv.h"
+
+#ifdef PNG_READ_SUPPORTED
+
+#if PNG_ARM_NEON_OPT > 0
+#ifdef PNG_ARM_NEON_CHECK_SUPPORTED /* Do run-time checks */
+/* WARNING: it is strongly recommended that you do not build libpng with
+ * run-time checks for CPU features if at all possible. In the case of the ARM
+ * NEON instructions there is no processor-specific way of detecting the
+ * presence of the required support, therefore run-time detection is extremely
+ * OS specific.
+ *
+ * You may set the macro PNG_ARM_NEON_FILE to the file name of file containing
+ * a fragment of C source code which defines the png_have_neon function. There
+ * are a number of implementations in contrib/arm-neon, but the only one that
+ * has partial support is contrib/arm-neon/linux.c - a generic Linux
+ * implementation which reads /proc/cpufino.
+ */
+#ifndef PNG_ARM_NEON_FILE
+# ifdef __linux__
+# define PNG_ARM_NEON_FILE "contrib/arm-neon/linux.c"
+# endif
+#endif
+
+#ifdef PNG_ARM_NEON_FILE
+
+#include <signal.h> /* for sig_atomic_t */
+static int png_have_neon(png_structp png_ptr);
+#include PNG_ARM_NEON_FILE
+
+#else /* PNG_ARM_NEON_FILE */
+# error "PNG_ARM_NEON_FILE undefined: no support for run-time ARM NEON checks"
+#endif /* PNG_ARM_NEON_FILE */
+#endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
+
+#ifndef PNG_ALIGNED_MEMORY_SUPPORTED
+# error "ALIGNED_MEMORY is required; set: -DPNG_ALIGNED_MEMORY_SUPPORTED"
+#endif
+
+void
+png_init_filter_functions_neon(png_structp pp, unsigned int bpp)
+{
+ /* The switch statement is compiled in for ARM_NEON_API, the call to
+ * png_have_neon is compiled in for ARM_NEON_CHECK. If both are defined
+ * the check is only performed if the API has not set the NEON option on
+ * or off explicitly. In this case the check controls what happens.
+ *
+ * If the CHECK is not compiled in and the option is UNSET the behavior prior
+ * to 1.6.7 was to use the NEON code - this was a bug caused by having the
+ * wrong order of the 'ON' and 'default' cases. UNSET now defaults to OFF,
+ * as documented in png.h
+ */
+#ifdef PNG_ARM_NEON_API_SUPPORTED
+ switch ((pp->options >> PNG_ARM_NEON) & 3)
+ {
+ case PNG_OPTION_UNSET:
+ /* Allow the run-time check to execute if it has been enabled -
+ * thus both API and CHECK can be turned on. If it isn't supported
+ * this case will fall through to the 'default' below, which just
+ * returns.
+ */
+#endif /* PNG_ARM_NEON_API_SUPPORTED */
+#ifdef PNG_ARM_NEON_CHECK_SUPPORTED
+ {
+ static volatile sig_atomic_t no_neon = -1; /* not checked */
+
+ if (no_neon < 0)
+ no_neon = !png_have_neon(pp);
+
+ if (no_neon)
+ return;
+ }
+#ifdef PNG_ARM_NEON_API_SUPPORTED
+ break;
+#endif
+#endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
+
+#ifdef PNG_ARM_NEON_API_SUPPORTED
+ default: /* OFF or INVALID */
+ return;
+
+ case PNG_OPTION_ON:
+ /* Option turned on */
+ break;
+ }
+#endif
+
+ /* IMPORTANT: any new external functions used here must be declared using
+ * PNG_INTERNAL_FUNCTION in ../pngpriv.h. This is required so that the
+ * 'prefix' option to configure works:
+ *
+ * ./configure --with-libpng-prefix=foobar_
+ *
+ * Verify you have got this right by running the above command, doing a build
+ * and examining pngprefix.h; it must contain a #define for every external
+ * function you add. (Notice that this happens automatically for the
+ * initialization function.)
+ */
+ pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up_neon;
+
+ if (bpp == 3)
+ {
+ pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_neon;
+ pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_neon;
+ pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
+ png_read_filter_row_paeth3_neon;
+ }
+
+ else if (bpp == 4)
+ {
+ pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_neon;
+ pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_neon;
+ pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
+ png_read_filter_row_paeth4_neon;
+ }
+}
+#endif /* PNG_ARM_NEON_OPT > 0 */
+#endif /* READ */
diff --git a/libpng/arm/filter_neon.S b/libpng/arm/filter_neon.S
new file mode 100644
index 0000000..3b061d6
--- /dev/null
+++ b/libpng/arm/filter_neon.S
@@ -0,0 +1,253 @@
+
+/* filter_neon.S - NEON optimised filter functions
+ *
+ * Copyright (c) 2014 Glenn Randers-Pehrson
+ * Written by Mans Rullgard, 2011.
+ * Last changed in libpng 1.6.16 [December 22, 2014]
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ */
+
+/* This is required to get the symbol renames, which are #defines, and the
+ * definitions (or not) of PNG_ARM_NEON_OPT and PNG_ARM_NEON_IMPLEMENTATION.
+ */
+#define PNG_VERSION_INFO_ONLY
+#include "../pngpriv.h"
+
+#if defined(__linux__) && defined(__ELF__)
+.section .note.GNU-stack,"",%progbits /* mark stack as non-executable */
+#endif
+
+#ifdef PNG_READ_SUPPORTED
+
+/* Assembler NEON support - only works for 32-bit ARM (i.e. it does not work for
+ * ARM64). The code in arm/filter_neon_intrinsics.c supports ARM64, however it
+ * only works if -mfpu=neon is specified on the GCC command line. See pngpriv.h
+ * for the logic which sets PNG_USE_ARM_NEON_ASM:
+ */
+#if PNG_ARM_NEON_IMPLEMENTATION == 2 /* hand-coded assembler */
+
+#if PNG_ARM_NEON_OPT > 0
+
+#ifdef __ELF__
+# define ELF
+#else
+# define ELF @
+#endif
+
+ .arch armv7-a
+ .fpu neon
+
+.macro func name, export=0
+ .macro endfunc
+ELF .size \name, . - \name
+ .endfunc
+ .purgem endfunc
+ .endm
+ .text
+
+ /* Explicitly specifying alignment here because some versions of
+ * GAS don't align code correctly. This is harmless in correctly
+ * written versions of GAS.
+ */
+ .align 2
+
+ .if \export
+ .global \name
+ .endif
+ELF .type \name, STT_FUNC
+ .func \name
+\name:
+.endm
+
+func png_read_filter_row_sub4_neon, export=1
+ ldr r3, [r0, #4] @ rowbytes
+ vmov.i8 d3, #0
+1:
+ vld4.32 {d4[],d5[],d6[],d7[]}, [r1,:128]
+ vadd.u8 d0, d3, d4
+ vadd.u8 d1, d0, d5
+ vadd.u8 d2, d1, d6
+ vadd.u8 d3, d2, d7
+ vst4.32 {d0[0],d1[0],d2[0],d3[0]},[r1,:128]!
+ subs r3, r3, #16
+ bgt 1b
+
+ bx lr
+endfunc
+
+func png_read_filter_row_sub3_neon, export=1
+ ldr r3, [r0, #4] @ rowbytes
+ vmov.i8 d3, #0
+ mov r0, r1
+ mov r2, #3
+ mov r12, #12
+ vld1.8 {q11}, [r0], r12
+1:
+ vext.8 d5, d22, d23, #3
+ vadd.u8 d0, d3, d22
+ vext.8 d6, d22, d23, #6
+ vadd.u8 d1, d0, d5
+ vext.8 d7, d23, d23, #1
+ vld1.8 {q11}, [r0], r12
+ vst1.32 {d0[0]}, [r1,:32], r2
+ vadd.u8 d2, d1, d6
+ vst1.32 {d1[0]}, [r1], r2
+ vadd.u8 d3, d2, d7
+ vst1.32 {d2[0]}, [r1], r2
+ vst1.32 {d3[0]}, [r1], r2
+ subs r3, r3, #12
+ bgt 1b
+
+ bx lr
+endfunc
+
+func png_read_filter_row_up_neon, export=1
+ ldr r3, [r0, #4] @ rowbytes
+1:
+ vld1.8 {q0}, [r1,:128]
+ vld1.8 {q1}, [r2,:128]!
+ vadd.u8 q0, q0, q1
+ vst1.8 {q0}, [r1,:128]!
+ subs r3, r3, #16
+ bgt 1b
+
+ bx lr
+endfunc
+
+func png_read_filter_row_avg4_neon, export=1
+ ldr r12, [r0, #4] @ rowbytes
+ vmov.i8 d3, #0
+1:
+ vld4.32 {d4[],d5[],d6[],d7[]}, [r1,:128]
+ vld4.32 {d16[],d17[],d18[],d19[]},[r2,:128]!
+ vhadd.u8 d0, d3, d16
+ vadd.u8 d0, d0, d4
+ vhadd.u8 d1, d0, d17
+ vadd.u8 d1, d1, d5
+ vhadd.u8 d2, d1, d18
+ vadd.u8 d2, d2, d6
+ vhadd.u8 d3, d2, d19
+ vadd.u8 d3, d3, d7
+ vst4.32 {d0[0],d1[0],d2[0],d3[0]},[r1,:128]!
+ subs r12, r12, #16
+ bgt 1b
+
+ bx lr
+endfunc
+
+func png_read_filter_row_avg3_neon, export=1
+ push {r4,lr}
+ ldr r12, [r0, #4] @ rowbytes
+ vmov.i8 d3, #0
+ mov r0, r1
+ mov r4, #3
+ mov lr, #12
+ vld1.8 {q11}, [r0], lr
+1:
+ vld1.8 {q10}, [r2], lr
+ vext.8 d5, d22, d23, #3
+ vhadd.u8 d0, d3, d20
+ vext.8 d17, d20, d21, #3
+ vadd.u8 d0, d0, d22
+ vext.8 d6, d22, d23, #6
+ vhadd.u8 d1, d0, d17
+ vext.8 d18, d20, d21, #6
+ vadd.u8 d1, d1, d5
+ vext.8 d7, d23, d23, #1
+ vld1.8 {q11}, [r0], lr
+ vst1.32 {d0[0]}, [r1,:32], r4
+ vhadd.u8 d2, d1, d18
+ vst1.32 {d1[0]}, [r1], r4
+ vext.8 d19, d21, d21, #1
+ vadd.u8 d2, d2, d6
+ vhadd.u8 d3, d2, d19
+ vst1.32 {d2[0]}, [r1], r4
+ vadd.u8 d3, d3, d7
+ vst1.32 {d3[0]}, [r1], r4
+ subs r12, r12, #12
+ bgt 1b
+
+ pop {r4,pc}
+endfunc
+
+.macro paeth rx, ra, rb, rc
+ vaddl.u8 q12, \ra, \rb @ a + b
+ vaddl.u8 q15, \rc, \rc @ 2*c
+ vabdl.u8 q13, \rb, \rc @ pa
+ vabdl.u8 q14, \ra, \rc @ pb
+ vabd.u16 q15, q12, q15 @ pc
+ vcle.u16 q12, q13, q14 @ pa <= pb
+ vcle.u16 q13, q13, q15 @ pa <= pc
+ vcle.u16 q14, q14, q15 @ pb <= pc
+ vand q12, q12, q13 @ pa <= pb && pa <= pc
+ vmovn.u16 d28, q14
+ vmovn.u16 \rx, q12
+ vbsl d28, \rb, \rc
+ vbsl \rx, \ra, d28
+.endm
+
+func png_read_filter_row_paeth4_neon, export=1
+ ldr r12, [r0, #4] @ rowbytes
+ vmov.i8 d3, #0
+ vmov.i8 d20, #0
+1:
+ vld4.32 {d4[],d5[],d6[],d7[]}, [r1,:128]
+ vld4.32 {d16[],d17[],d18[],d19[]},[r2,:128]!
+ paeth d0, d3, d16, d20
+ vadd.u8 d0, d0, d4
+ paeth d1, d0, d17, d16
+ vadd.u8 d1, d1, d5
+ paeth d2, d1, d18, d17
+ vadd.u8 d2, d2, d6
+ paeth d3, d2, d19, d18
+ vmov d20, d19
+ vadd.u8 d3, d3, d7
+ vst4.32 {d0[0],d1[0],d2[0],d3[0]},[r1,:128]!
+ subs r12, r12, #16
+ bgt 1b
+
+ bx lr
+endfunc
+
+func png_read_filter_row_paeth3_neon, export=1
+ push {r4,lr}
+ ldr r12, [r0, #4] @ rowbytes
+ vmov.i8 d3, #0
+ vmov.i8 d4, #0
+ mov r0, r1
+ mov r4, #3
+ mov lr, #12
+ vld1.8 {q11}, [r0], lr
+1:
+ vld1.8 {q10}, [r2], lr
+ paeth d0, d3, d20, d4
+ vext.8 d5, d22, d23, #3
+ vadd.u8 d0, d0, d22
+ vext.8 d17, d20, d21, #3
+ paeth d1, d0, d17, d20
+ vst1.32 {d0[0]}, [r1,:32], r4
+ vext.8 d6, d22, d23, #6
+ vadd.u8 d1, d1, d5
+ vext.8 d18, d20, d21, #6
+ paeth d2, d1, d18, d17
+ vext.8 d7, d23, d23, #1
+ vld1.8 {q11}, [r0], lr
+ vst1.32 {d1[0]}, [r1], r4
+ vadd.u8 d2, d2, d6
+ vext.8 d19, d21, d21, #1
+ paeth d3, d2, d19, d18
+ vst1.32 {d2[0]}, [r1], r4
+ vmov d4, d19
+ vadd.u8 d3, d3, d7
+ vst1.32 {d3[0]}, [r1], r4
+ subs r12, r12, #12
+ bgt 1b
+
+ pop {r4,pc}
+endfunc
+#endif /* PNG_ARM_NEON_OPT > 0 */
+#endif /* PNG_ARM_NEON_IMPLEMENTATION == 2 (assembler) */
+#endif /* READ */
diff --git a/libpng/arm/filter_neon_intrinsics.c b/libpng/arm/filter_neon_intrinsics.c
new file mode 100644
index 0000000..d42c788
--- /dev/null
+++ b/libpng/arm/filter_neon_intrinsics.c
@@ -0,0 +1,373 @@
+
+/* filter_neon_intrinsics.c - NEON optimised filter functions
+ *
+ * Copyright (c) 2014 Glenn Randers-Pehrson
+ * Written by James Yu <james.yu at linaro.org>, October 2013.
+ * Based on filter_neon.S, written by Mans Rullgard, 2011.
+ *
+ * Last changed in libpng 1.6.16 [December 22, 2014]
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ */
+
+#include "../pngpriv.h"
+
+#ifdef PNG_READ_SUPPORTED
+
+/* This code requires -mfpu=neon on the command line: */
+#if PNG_ARM_NEON_IMPLEMENTATION == 1 /* intrinsics code from pngpriv.h */
+
+#include <arm_neon.h>
+
+/* libpng row pointers are not necessarily aligned to any particular boundary,
+ * however this code will only work with appropriate alignment. arm/arm_init.c
+ * checks for this (and will not compile unless it is done). This code uses
+ * variants of png_aligncast to avoid compiler warnings.
+ */
+#define png_ptr(type,pointer) png_aligncast(type *,pointer)
+#define png_ptrc(type,pointer) png_aligncastconst(const type *,pointer)
+
+/* The following relies on a variable 'temp_pointer' being declared with type
+ * 'type'. This is written this way just to hide the GCC strict aliasing
+ * warning; note that the code is safe because there never is an alias between
+ * the input and output pointers.
+ */
+#define png_ldr(type,pointer)\
+ (temp_pointer = png_ptr(type,pointer), *temp_pointer)
+
+#if PNG_ARM_NEON_OPT > 0
+
+void
+png_read_filter_row_up_neon(png_row_infop row_info, png_bytep row,
+ png_const_bytep prev_row)
+{
+ png_bytep rp = row;
+ png_bytep rp_stop = row + row_info->rowbytes;
+ png_const_bytep pp = prev_row;
+
+ for (; rp < rp_stop; rp += 16, pp += 16)
+ {
+ uint8x16_t qrp, qpp;
+
+ qrp = vld1q_u8(rp);
+ qpp = vld1q_u8(pp);
+ qrp = vaddq_u8(qrp, qpp);
+ vst1q_u8(rp, qrp);
+ }
+}
+
+void
+png_read_filter_row_sub3_neon(png_row_infop row_info, png_bytep row,
+ png_const_bytep prev_row)
+{
+ png_bytep rp = row;
+ png_bytep rp_stop = row + row_info->rowbytes;
+
+ uint8x16_t vtmp = vld1q_u8(rp);
+ uint8x8x2_t *vrpt = png_ptr(uint8x8x2_t, &vtmp);
+ uint8x8x2_t vrp = *vrpt;
+
+ uint8x8x4_t vdest;
+ vdest.val[3] = vdup_n_u8(0);
+
+ for (; rp < rp_stop;)
+ {
+ uint8x8_t vtmp1, vtmp2;
+ uint32x2_t *temp_pointer;
+
+ vtmp1 = vext_u8(vrp.val[0], vrp.val[1], 3);
+ vdest.val[0] = vadd_u8(vdest.val[3], vrp.val[0]);
+ vtmp2 = vext_u8(vrp.val[0], vrp.val[1], 6);
+ vdest.val[1] = vadd_u8(vdest.val[0], vtmp1);
+
+ vtmp1 = vext_u8(vrp.val[1], vrp.val[1], 1);
+ vdest.val[2] = vadd_u8(vdest.val[1], vtmp2);
+ vdest.val[3] = vadd_u8(vdest.val[2], vtmp1);
+
+ vtmp = vld1q_u8(rp + 12);
+ vrpt = png_ptr(uint8x8x2_t, &vtmp);
+ vrp = *vrpt;
+
+ vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[0]), 0);
+ rp += 3;
+ vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[1]), 0);
+ rp += 3;
+ vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[2]), 0);
+ rp += 3;
+ vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[3]), 0);
+ rp += 3;
+ }
+
+ PNG_UNUSED(prev_row)
+}
+
+void
+png_read_filter_row_sub4_neon(png_row_infop row_info, png_bytep row,
+ png_const_bytep prev_row)
+{
+ png_bytep rp = row;
+ png_bytep rp_stop = row + row_info->rowbytes;
+
+ uint8x8x4_t vdest;
+ vdest.val[3] = vdup_n_u8(0);
+
+ for (; rp < rp_stop; rp += 16)
+ {
+ uint32x2x4_t vtmp = vld4_u32(png_ptr(uint32_t,rp));
+ uint8x8x4_t *vrpt = png_ptr(uint8x8x4_t,&vtmp);
+ uint8x8x4_t vrp = *vrpt;
+ uint32x2x4_t *temp_pointer;
+
+ vdest.val[0] = vadd_u8(vdest.val[3], vrp.val[0]);
+ vdest.val[1] = vadd_u8(vdest.val[0], vrp.val[1]);
+ vdest.val[2] = vadd_u8(vdest.val[1], vrp.val[2]);
+ vdest.val[3] = vadd_u8(vdest.val[2], vrp.val[3]);
+ vst4_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2x4_t,&vdest), 0);
+ }
+
+ PNG_UNUSED(prev_row)
+}
+
+void
+png_read_filter_row_avg3_neon(png_row_infop row_info, png_bytep row,
+ png_const_bytep prev_row)
+{
+ png_bytep rp = row;
+ png_const_bytep pp = prev_row;
+ png_bytep rp_stop = row + row_info->rowbytes;
+
+ uint8x16_t vtmp;
+ uint8x8x2_t *vrpt;
+ uint8x8x2_t vrp;
+ uint8x8x4_t vdest;
+ vdest.val[3] = vdup_n_u8(0);
+
+ vtmp = vld1q_u8(rp);
+ vrpt = png_ptr(uint8x8x2_t,&vtmp);
+ vrp = *vrpt;
+
+ for (; rp < rp_stop; pp += 12)
+ {
+ uint8x8_t vtmp1, vtmp2, vtmp3;
+
+ uint8x8x2_t *vppt;
+ uint8x8x2_t vpp;
+
+ uint32x2_t *temp_pointer;
+
+ vtmp = vld1q_u8(pp);
+ vppt = png_ptr(uint8x8x2_t,&vtmp);
+ vpp = *vppt;
+
+ vtmp1 = vext_u8(vrp.val[0], vrp.val[1], 3);
+ vdest.val[0] = vhadd_u8(vdest.val[3], vpp.val[0]);
+ vdest.val[0] = vadd_u8(vdest.val[0], vrp.val[0]);
+
+ vtmp2 = vext_u8(vpp.val[0], vpp.val[1], 3);
+ vtmp3 = vext_u8(vrp.val[0], vrp.val[1], 6);
+ vdest.val[1] = vhadd_u8(vdest.val[0], vtmp2);
+ vdest.val[1] = vadd_u8(vdest.val[1], vtmp1);
+
+ vtmp2 = vext_u8(vpp.val[0], vpp.val[1], 6);
+ vtmp1 = vext_u8(vrp.val[1], vrp.val[1], 1);
+
+ vtmp = vld1q_u8(rp + 12);
+ vrpt = png_ptr(uint8x8x2_t,&vtmp);
+ vrp = *vrpt;
+
+ vdest.val[2] = vhadd_u8(vdest.val[1], vtmp2);
+ vdest.val[2] = vadd_u8(vdest.val[2], vtmp3);
+
+ vtmp2 = vext_u8(vpp.val[1], vpp.val[1], 1);
+
+ vdest.val[3] = vhadd_u8(vdest.val[2], vtmp2);
+ vdest.val[3] = vadd_u8(vdest.val[3], vtmp1);
+
+ vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[0]), 0);
+ rp += 3;
+ vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[1]), 0);
+ rp += 3;
+ vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[2]), 0);
+ rp += 3;
+ vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[3]), 0);
+ rp += 3;
+ }
+}
+
+void
+png_read_filter_row_avg4_neon(png_row_infop row_info, png_bytep row,
+ png_const_bytep prev_row)
+{
+ png_bytep rp = row;
+ png_bytep rp_stop = row + row_info->rowbytes;
+ png_const_bytep pp = prev_row;
+
+ uint8x8x4_t vdest;
+ vdest.val[3] = vdup_n_u8(0);
+
+ for (; rp < rp_stop; rp += 16, pp += 16)
+ {
+ uint32x2x4_t vtmp;
+ uint8x8x4_t *vrpt, *vppt;
+ uint8x8x4_t vrp, vpp;
+ uint32x2x4_t *temp_pointer;
+
+ vtmp = vld4_u32(png_ptr(uint32_t,rp));
+ vrpt = png_ptr(uint8x8x4_t,&vtmp);
+ vrp = *vrpt;
+ vtmp = vld4_u32(png_ptrc(uint32_t,pp));
+ vppt = png_ptr(uint8x8x4_t,&vtmp);
+ vpp = *vppt;
+
+ vdest.val[0] = vhadd_u8(vdest.val[3], vpp.val[0]);
+ vdest.val[0] = vadd_u8(vdest.val[0], vrp.val[0]);
+ vdest.val[1] = vhadd_u8(vdest.val[0], vpp.val[1]);
+ vdest.val[1] = vadd_u8(vdest.val[1], vrp.val[1]);
+ vdest.val[2] = vhadd_u8(vdest.val[1], vpp.val[2]);
+ vdest.val[2] = vadd_u8(vdest.val[2], vrp.val[2]);
+ vdest.val[3] = vhadd_u8(vdest.val[2], vpp.val[3]);
+ vdest.val[3] = vadd_u8(vdest.val[3], vrp.val[3]);
+
+ vst4_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2x4_t,&vdest), 0);
+ }
+}
+
+static uint8x8_t
+paeth(uint8x8_t a, uint8x8_t b, uint8x8_t c)
+{
+ uint8x8_t d, e;
+ uint16x8_t p1, pa, pb, pc;
+
+ p1 = vaddl_u8(a, b); /* a + b */
+ pc = vaddl_u8(c, c); /* c * 2 */
+ pa = vabdl_u8(b, c); /* pa */
+ pb = vabdl_u8(a, c); /* pb */
+ pc = vabdq_u16(p1, pc); /* pc */
+
+ p1 = vcleq_u16(pa, pb); /* pa <= pb */
+ pa = vcleq_u16(pa, pc); /* pa <= pc */
+ pb = vcleq_u16(pb, pc); /* pb <= pc */
+
+ p1 = vandq_u16(p1, pa); /* pa <= pb && pa <= pc */
+
+ d = vmovn_u16(pb);
+ e = vmovn_u16(p1);
+
+ d = vbsl_u8(d, b, c);
+ e = vbsl_u8(e, a, d);
+
+ return e;
+}
+
+void
+png_read_filter_row_paeth3_neon(png_row_infop row_info, png_bytep row,
+ png_const_bytep prev_row)
+{
+ png_bytep rp = row;
+ png_const_bytep pp = prev_row;
+ png_bytep rp_stop = row + row_info->rowbytes;
+
+ uint8x16_t vtmp;
+ uint8x8x2_t *vrpt;
+ uint8x8x2_t vrp;
+ uint8x8_t vlast = vdup_n_u8(0);
+ uint8x8x4_t vdest;
+ vdest.val[3] = vdup_n_u8(0);
+
+ vtmp = vld1q_u8(rp);
+ vrpt = png_ptr(uint8x8x2_t,&vtmp);
+ vrp = *vrpt;
+
+ for (; rp < rp_stop; pp += 12)
+ {
+ uint8x8x2_t *vppt;
+ uint8x8x2_t vpp;
+ uint8x8_t vtmp1, vtmp2, vtmp3;
+ uint32x2_t *temp_pointer;
+
+ vtmp = vld1q_u8(pp);
+ vppt = png_ptr(uint8x8x2_t,&vtmp);
+ vpp = *vppt;
+
+ vdest.val[0] = paeth(vdest.val[3], vpp.val[0], vlast);
+ vdest.val[0] = vadd_u8(vdest.val[0], vrp.val[0]);
+
+ vtmp1 = vext_u8(vrp.val[0], vrp.val[1], 3);
+ vtmp2 = vext_u8(vpp.val[0], vpp.val[1], 3);
+ vdest.val[1] = paeth(vdest.val[0], vtmp2, vpp.val[0]);
+ vdest.val[1] = vadd_u8(vdest.val[1], vtmp1);
+
+ vtmp1 = vext_u8(vrp.val[0], vrp.val[1], 6);
+ vtmp3 = vext_u8(vpp.val[0], vpp.val[1], 6);
+ vdest.val[2] = paeth(vdest.val[1], vtmp3, vtmp2);
+ vdest.val[2] = vadd_u8(vdest.val[2], vtmp1);
+
+ vtmp1 = vext_u8(vrp.val[1], vrp.val[1], 1);
+ vtmp2 = vext_u8(vpp.val[1], vpp.val[1], 1);
+
+ vtmp = vld1q_u8(rp + 12);
+ vrpt = png_ptr(uint8x8x2_t,&vtmp);
+ vrp = *vrpt;
+
+ vdest.val[3] = paeth(vdest.val[2], vtmp2, vtmp3);
+ vdest.val[3] = vadd_u8(vdest.val[3], vtmp1);
+
+ vlast = vtmp2;
+
+ vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[0]), 0);
+ rp += 3;
+ vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[1]), 0);
+ rp += 3;
+ vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[2]), 0);
+ rp += 3;
+ vst1_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2_t,&vdest.val[3]), 0);
+ rp += 3;
+ }
+}
+
+void
+png_read_filter_row_paeth4_neon(png_row_infop row_info, png_bytep row,
+ png_const_bytep prev_row)
+{
+ png_bytep rp = row;
+ png_bytep rp_stop = row + row_info->rowbytes;
+ png_const_bytep pp = prev_row;
+
+ uint8x8_t vlast = vdup_n_u8(0);
+ uint8x8x4_t vdest;
+ vdest.val[3] = vdup_n_u8(0);
+
+ for (; rp < rp_stop; rp += 16, pp += 16)
+ {
+ uint32x2x4_t vtmp;
+ uint8x8x4_t *vrpt, *vppt;
+ uint8x8x4_t vrp, vpp;
+ uint32x2x4_t *temp_pointer;
+
+ vtmp = vld4_u32(png_ptr(uint32_t,rp));
+ vrpt = png_ptr(uint8x8x4_t,&vtmp);
+ vrp = *vrpt;
+ vtmp = vld4_u32(png_ptrc(uint32_t,pp));
+ vppt = png_ptr(uint8x8x4_t,&vtmp);
+ vpp = *vppt;
+
+ vdest.val[0] = paeth(vdest.val[3], vpp.val[0], vlast);
+ vdest.val[0] = vadd_u8(vdest.val[0], vrp.val[0]);
+ vdest.val[1] = paeth(vdest.val[0], vpp.val[1], vpp.val[0]);
+ vdest.val[1] = vadd_u8(vdest.val[1], vrp.val[1]);
+ vdest.val[2] = paeth(vdest.val[1], vpp.val[2], vpp.val[1]);
+ vdest.val[2] = vadd_u8(vdest.val[2], vrp.val[2]);
+ vdest.val[3] = paeth(vdest.val[2], vpp.val[3], vpp.val[2]);
+ vdest.val[3] = vadd_u8(vdest.val[3], vrp.val[3]);
+
+ vlast = vpp.val[3];
+
+ vst4_lane_u32(png_ptr(uint32_t,rp), png_ldr(uint32x2x4_t,&vdest), 0);
+ }
+}
+
+#endif /* PNG_ARM_NEON_OPT > 0 */
+#endif /* PNG_ARM_NEON_IMPLEMENTATION == 1 (intrinsics) */
+#endif /* READ */
diff --git a/libpng/autogen.sh b/libpng/autogen.sh
new file mode 100755
index 0000000..9160717
--- /dev/null
+++ b/libpng/autogen.sh
@@ -0,0 +1,225 @@
+#! /bin/sh
+#
+# Run 'autoreconf' to build 'configure', 'Makefile.in' and other configure
+# control files.
+#
+# The first time this is run on a GIT checkout the only files that exist are
+# configure.ac and Makefile.am; all of the autotools support scripts are
+# missing. They are instantiated with autoreconf --force --install.
+#
+# For regular ("tarball") distributions all the files should exist. We do not
+# want them to be updated *under any circumstances*. It should never be
+# necessary to run autogen.sh because ./configure --enable-maintainer-mode says
+# what to do if Makefile.am or configure.ac are changed.
+#
+# It is *probably* OK to update the files on a GIT checkout, because they have
+# come from the local tools, but leave that to the user who is assumed to know
+# whether it is ok or required.
+#
+# This script is intended to work without arguments, there are, however, hidden
+# arguments (a) for use while testing the script and (b) to fix up systems that
+# have been broken. If (b) is required the script prompts for the correct
+# options. For this reason the options are *NOT* documented in the help; this
+# is deliberate; UTSL.
+#
+clean=
+maintainer=
+while test $# -gt 0
+do
+ case "$1" in
+ --maintainer)
+ maintainer=1;;
+
+ --clean)
+ clean=1;;
+
+ *)
+ exec >&2
+ echo "$0: usage: ./autogen.sh"
+ if test -d .git
+ then
+ echo " ./autogen.sh generates the configure script and"
+ echo " Makefile.in, or refreshes them after changes to Makefile.am"
+ echo " or configure.ac. You may prefer to just run autoreconf."
+ elif test -z "$maintainer"
+ then
+ echo " DO NOT RUN THIS SCRIPT."
+ echo " If you need to change Makefile.am or configure.ac then you"
+ echo " also need to run ./configure --enable-maintainer-mode and"
+ echo " use the appropriate autotools, *NOT* this script, to update"
+ echo " everything, please check the documentation of autoreconf."
+ echo " WARNING: libpng is intentionally generated with a known,"
+ echo " fixed, set of autotools. It is known *NOT* to work with"
+ echo " the collection of autotools distributed on highly reputable"
+ echo " operating systems."
+ echo " Remember: autotools is GNU software, you are expected to"
+ echo " pay for support."
+ else
+ echo " You have run autogen.sh with --maintainer enabled and you"
+ echo " are not using a GIT distribution, then you have given an"
+ echo " unrecognized argument. This is not good. --maintainer"
+ echo " switches off any assumptions that you might not know what"
+ echo " you are doing."
+ fi
+ exit 1;;
+ esac
+
+ shift
+done
+#
+# First check for a set of the autotools files; if absent then this is assumed
+# to be a GIT version and the local autotools must be used. If present this
+# is a tarball distribution and the script should not be used. If partially
+# present bad things are happening.
+#
+# The autotools generated files:
+libpng_autotools_files="Makefile.in aclocal.m4 config.guess config.h.in
+ config.sub configure depcomp install-sh ltmain.sh missing\
+ test-driver"
+#
+# Files generated by versions of configue >2.68 or automake >1.13 (i.e. later
+# versions than those required by configure.ac):
+libpng_autotools_extra="compile config.h.in~"
+#
+# These are separate because 'maintainer-clean' does not remove them.
+libpng_libtool_files="scripts/libtool.m4 scripts/ltoptions.m4\
+ scripts/ltsugar.m4 scripts/ltversion.m4 scripts/lt~obsolete.m4"
+
+libpng_autotools_dirs="autom4te.cache" # not required
+#
+# The configure generated files:
+libpng_configure_files="Makefile config.h config.log config.status\
+ libpng-config libpng.pc libtool stamp-h1"
+
+libpng_configure_dirs=".deps"
+#
+# We must remove the configure generated files as well as the autotools
+# generated files if autotools are regenerated because otherwise if configure
+# has been run without "--enable-maintainer-mode" make can do a partial update
+# of Makefile. These functions do the two bits of cleaning.
+clean_autotools(){
+ rm -rf $libpng_autotools_files $libpng_libtool_files $libpng_autotools_dirs
+ rm -rf $libpng_autotools_extra
+}
+
+clean_configure(){
+ rm -rf $libpng_configure_files $libpng_configure_dirs
+}
+#
+# Clean: remove everything (this is to help with testing)
+if test -n "$clean"
+then
+ clean_configure
+ if test -n "$maintainer"
+ then
+ clean_autotools
+ fi
+
+ exit 0
+fi
+#
+# Validate the distribution.
+libpng_autotools_file_found=
+libpng_autotools_file_missing=
+for file in $libpng_autotools_files
+do
+ if test -f "$file"
+ then
+ libpng_autotools_file_found=1
+ else
+ libpng_autotools_file_missing=1
+ fi
+done
+#
+# Presence of one of these does not *invalidate* missing, but absence
+# invalidates found.
+for file in $libpng_libtool_files
+do
+ if test ! -f "$file"
+ then
+ libpng_autotools_file_missing=1
+ fi
+done
+#
+# The cache directory doesn't matter - it will be regenerated and does not exist
+# anyway in a tarball.
+#
+# Either everything is missing or everything is there, the --maintainer option
+# just changes this so that the mode is set to generate all the files.
+mode=
+if test -z "$libpng_autotools_file_found" -o -n "$maintainer"
+then
+ mode="autoreconf"
+else
+ if test -n "$libpng_autotools_file_missing"
+ then
+ mode="broken"
+ else
+ mode="configure"
+ fi
+fi
+#
+# So:
+case "$mode" in
+ autoreconf)
+ # Clean in case configure files exist
+ clean_configure
+ clean_autotools
+ # Everything must be initialized, so use --force
+ if autoreconf --warnings=all --force --install
+ then
+ missing=
+ for file in $libpng_autotools_files
+ do
+ test -f "$file" || missing=1
+ done
+ # ignore the cache directory
+ test -z "$missing" || {
+ exec >&2
+ echo "autoreconf was run, but did not produce all the expected"
+ echo "files. It is likely that your autotools installation is"
+ echo "not compatible with that expected by libpng."
+ exit 1
+ }
+ else
+ exec >&2
+ echo "autoreconf failed: your version of autotools is incompatible"
+ echo "with this libpng version. Please use a distributed archive"
+ echo "(which includes the autotools generated files) and run configure"
+ echo "instead."
+ exit 1
+ fi;;
+
+ configure)
+ if test -d .git
+ then
+ exec >&2
+ echo "ERROR: running autoreconf on an initialized sytem"
+ echo " This is not necessary; it is only necessary to remake the"
+ echo " autotools generated files if Makefile.am or configure.ac"
+ echo " change and make does the right thing with:"
+ echo
+ echo " ./configure --enable-maintainer-mode."
+ echo
+ echo " You can run autoreconf yourself if you don't like maintainer"
+ echo " mode and you can also just run autoreconf -f -i to initialize"
+ echo " everything in the first place; this script is only for"
+ echo " compatibility with prior releases."
+ exit 1
+ else
+ exec >&2
+ echo "autogen.sh is intended only to generate 'configure' on systems"
+ echo "that do not have it. You have a complete 'configure', if you"
+ echo "need to change Makefile.am or configure.ac you also need to"
+ echo "run configure with the --enable-maintainer-mode option."
+ exit 1
+ fi;;
+
+ broken)
+ exec >&2
+ echo "Your system has a partial set of autotools generated files."
+ echo "autogen.sh is unable to proceed. The full set of files is"
+ echo "contained in the libpng 'tar' distribution archive and you do"
+ echo "not need to run autogen.sh if you use it."
+ exit 1;;
+esac
diff --git a/libpng/configure.ac b/libpng/configure.ac
new file mode 100644
index 0000000..845ae1c
--- /dev/null
+++ b/libpng/configure.ac
@@ -0,0 +1,324 @@
+# configure.ac
+
+dnl Process this file with autoconf to produce a configure script.
+dnl
+dnl Minor upgrades (compatible ABI): increment the package version
+dnl (third field in two places below) and set the PNGLIB_RELEASE
+dnl variable.
+dnl
+dnl Major upgrades (incompatible ABI): increment the package major
+dnl version (second field, or first if desired), set the minor
+dnl to 0, set PNGLIB_MAJOR below *and* follow the instructions in
+dnl Makefile.am to upgrade the package name.
+
+dnl This is here to prevent earlier autoconf from being used, it
+dnl should not be necessary to regenerate configure if the time
+dnl stamps are correct
+AC_PREREQ([2.68])
+
+dnl Version number stuff here:
+
+AC_INIT([libpng],[1.6.20],[png-mng-implement@lists.sourceforge.net])
+AC_CONFIG_MACRO_DIR([scripts])
+
+# libpng does not follow GNU file name conventions (hence 'foreign')
+# color-tests requires automake 1.11 or later
+# silent-rules requires automake 1.11 or later
+# dist-xz requires automake 1.11 or later
+# 1.12.2 fixes a security issue in 1.11.2 and 1.12.1
+# 1.13 is required for parallel tests
+AM_INIT_AUTOMAKE([1.13 foreign dist-xz color-tests silent-rules subdir-objects])
+# The following line causes --disable-maintainer-mode to be the default to
+# configure, this is necessary because libpng distributions cannot rely on the
+# time stamps of the autotools generated files being correct
+AM_MAINTAINER_MODE
+
+dnl configure.ac and Makefile.am expect automake 1.11.2 or a compatible later
+dnl version; aclocal.m4 will generate a failure if you use a prior version of
+dnl automake, so the following is not necessary (and is not defined anyway):
+dnl AM_PREREQ([1.11.2])
+dnl stop configure from automagically running automake
+
+PNGLIB_VERSION=1.6.20
+PNGLIB_MAJOR=1
+PNGLIB_MINOR=6
+PNGLIB_RELEASE=20
+
+dnl End of version number stuff
+
+AC_CONFIG_SRCDIR([pngget.c])
+AC_CONFIG_HEADERS([config.h])
+
+# Checks for programs.
+AC_LANG([C])
+AC_PROG_CC
+AM_PROG_AS
+LT_PATH_LD
+AC_PROG_CPP
+AC_PROG_AWK
+AC_PROG_INSTALL
+AC_PROG_LN_S
+AC_PROG_MAKE_SET
+
+dnl libtool/libtoolize; version 2.4.2 is the tested version, this or any
+dnl compatible later version may be used
+LT_INIT([win32-dll])
+LT_PREREQ([2.4.2])
+
+# Some awks crash when confronted with pnglibconf.dfa, do a test run now
+# to make sure this doesn't happen
+AC_MSG_CHECKING([that AWK works])
+if ${AWK} -f ${srcdir}/scripts/options.awk out="/dev/null" version=search\
+ ${srcdir}/pngconf.h ${srcdir}/scripts/pnglibconf.dfa\
+ ${srcdir}/pngusr.dfa 1>&2
+then
+ AC_MSG_RESULT([ok])
+else
+ AC_MSG_FAILURE([failed], 1)
+fi
+
+# This is a remnant of the old cc -E validation, where it may have been
+# necessary to use a different preprocessor for .dfn files
+DFNCPP="$CPP"
+AC_SUBST(DFNCPP)
+
+# -Werror cannot be passed to GCC in CFLAGS because configure will fail (it
+# checks the compiler with a program that generates a warning), add the
+# following option to deal with this
+AC_ARG_VAR(PNG_COPTS,
+ [additional flags for the C compiler, use this for options that would]
+ [cause configure itself to fail])
+AC_ARG_ENABLE(werror,
+ AS_HELP_STRING([[[--enable-werror[=OPT]]]],
+ [Pass -Werror or the given argument to the compiler if it is supported]),
+ [test "$enable_werror" = "yes" && enable_werror="-Werror"
+ if test "$enable_werror" != "no"; then
+ sav_CFLAGS="$CFLAGS"
+ CFLAGS="$enable_werror $CFLAGS"
+ AC_MSG_CHECKING([if the compiler allows $enable_werror])
+ AC_COMPILE_IFELSE(
+ [AC_LANG_SOURCE([
+ [int main(int argc, char **argv){]
+ [return argv[argc-1][0];]
+ [}]])],
+ AC_MSG_RESULT(yes)
+ PNG_COPTS="$PNG_COPTS $enable_werror",
+ AC_MSG_RESULT(no))
+ CFLAGS="$sav_CFLAGS"
+ fi],)
+
+# Checks for header files.
+AC_HEADER_STDC
+
+# Checks for typedefs, structures, and compiler characteristics.
+AC_C_CONST
+AC_TYPE_SIZE_T
+AC_STRUCT_TM
+AC_C_RESTRICT
+
+# Checks for library functions.
+AC_FUNC_STRTOD
+AC_CHECK_FUNCS([memset], , AC_MSG_ERROR(memset not found in libc))
+AC_CHECK_FUNCS([pow], , AC_CHECK_LIB(m, pow, , AC_MSG_ERROR(cannot find pow)) )
+AC_ARG_WITH(zlib-prefix,
+ AS_HELP_STRING([[[--with-zlib-prefix]]],
+ [prefix that may have been used in installed zlib]),
+ [ZPREFIX=${withval}],
+ [ZPREFIX='z_'])
+AC_CHECK_LIB(z, zlibVersion, ,
+ AC_CHECK_LIB(z, ${ZPREFIX}zlibVersion, , AC_MSG_ERROR(zlib not installed)))
+
+# The following is for pngvalid, to ensure it catches FP errors even on
+# platforms that don't enable FP exceptions, the function appears in the math
+# library (typically), it's not an error if it is not found.
+AC_CHECK_LIB([m], [feenableexcept])
+AC_CHECK_FUNCS([feenableexcept])
+
+AC_MSG_CHECKING([if using Solaris linker])
+SLD=`$LD --version 2>&1 | grep Solaris`
+if test "$SLD"; then
+ have_solaris_ld=yes
+ AC_MSG_RESULT(yes)
+else
+ have_solaris_ld=no
+ AC_MSG_RESULT(no)
+fi
+AM_CONDITIONAL(HAVE_SOLARIS_LD, test "$have_solaris_ld" = "yes")
+
+AC_MSG_CHECKING([if libraries can be versioned])
+# Special case for PE/COFF platforms: ld reports
+# support for version-script, but doesn't actually
+# DO anything with it.
+case $host in
+*cygwin* | *mingw32* | *interix* )
+ have_ld_version_script=no
+ AC_MSG_RESULT(no)
+;;
+* )
+
+if test "$have_solaris_ld" = "yes"; then
+ GLD=`$LD --help < /dev/null 2>&1 | grep 'M mapfile'`
+else
+ GLD=`$LD --help < /dev/null 2>/dev/null | grep version-script`
+fi
+
+if test "$GLD"; then
+ have_ld_version_script=yes
+ AC_MSG_RESULT(yes)
+else
+ have_ld_version_script=no
+ AC_MSG_RESULT(no)
+ AC_MSG_WARN(*** You have not enabled versioned symbols.)
+fi
+;;
+esac
+
+AM_CONDITIONAL(HAVE_LD_VERSION_SCRIPT, test "$have_ld_version_script" = "yes")
+
+if test "$have_ld_version_script" = "yes"; then
+ AC_MSG_CHECKING([for symbol prefix])
+ SYMBOL_PREFIX=`echo "PREFIX=__USER_LABEL_PREFIX__" \
+ | ${CPP-${CC-gcc} -E} - 2>&1 \
+ | ${EGREP-grep} "^PREFIX=" \
+ | ${SED-sed} -e "s:^PREFIX=::" -e "s:__USER_LABEL_PREFIX__::"`
+ AC_SUBST(SYMBOL_PREFIX)
+ AC_MSG_RESULT($SYMBOL_PREFIX)
+fi
+
+# Substitutions for .in files
+AC_SUBST(PNGLIB_VERSION)
+AC_SUBST(PNGLIB_MAJOR)
+AC_SUBST(PNGLIB_MINOR)
+AC_SUBST(PNGLIB_RELEASE)
+
+# Additional arguments (and substitutions)
+# Allow the pkg-config directory to be set
+AC_ARG_WITH(pkgconfigdir,
+ AS_HELP_STRING([[[--with-pkgconfigdir]]],
+ [Use the specified pkgconfig dir (default is libdir/pkgconfig)]),
+ [pkgconfigdir=${withval}],
+ [pkgconfigdir='${libdir}/pkgconfig'])
+
+AC_SUBST([pkgconfigdir])
+AC_MSG_NOTICE([[pkgconfig directory is ${pkgconfigdir}]])
+
+# Make the *-config binary config scripts optional
+AC_ARG_WITH(binconfigs,
+ AS_HELP_STRING([[[--with-binconfigs]]],
+ [Generate shell libpng-config scripts as well as pkg-config data]
+ [@<:@default=yes@:>@]),
+ [if test "${withval}" = no; then
+ binconfigs=
+ AC_MSG_NOTICE([[libpng-config scripts will not be built]])
+ else
+ binconfigs='${binconfigs}'
+ fi],
+ [binconfigs='${binconfigs}'])
+AC_SUBST([binconfigs])
+
+# Support for prefixes to the API function names; this will generate defines
+# at the start of the build to rename exported library functions
+AC_ARG_WITH(libpng-prefix,
+ AS_HELP_STRING([[[--with-libpng-prefix]]],
+ [prefix libpng exported function (API) names with the given value]),
+ [if test "${withval:-no}" != "no"; then
+ AC_SUBST([PNG_PREFIX], [${withval}])
+ fi])
+AM_CONDITIONAL([DO_PNG_PREFIX], [test "${with_libpng_prefix:-no}" != "no"])
+
+# Control over what links are made for installed files. Versioned files are
+# always installed, when the following options are turned on corresponding
+# unversioned links are also created (normally as symbolic links):
+AC_ARG_ENABLE([unversioned-links],
+ AS_HELP_STRING([[[--enable-unversioned-links]]],
+ [Installed libpng header files are placed in a versioned subdirectory]
+ [and installed libpng library (including DLL) files are versioned.]
+ [If this option is enabled unversioned links will be created pointing to]
+ [the corresponding installed files. If you use libpng.pc or]
+ [libpng-config for all builds you do not need these links, but if you]
+ [compile programs directly they will typically #include <png.h> and]
+ [link with -lpng; in that case you need the links.]
+ [The links can be installed manually using 'make install-header-links']
+ [and 'make install-library-links' and can be removed using the]
+ [corresponding uninstall- targets. If you do enable this option every]
+ [libpng 'make install' will recreate the links to point to the just]
+ [installed version of libpng. The default is to create the links;]
+ [use --disable-unversioned-links to change this]))
+
+# The AM_CONDITIONAL test is written so that the default is enabled;
+# --disable-unversioned-links must be given to turn the option off.
+AM_CONDITIONAL([DO_INSTALL_LINKS],[test "$enable_unversioned_links" != "no"])
+
+AC_ARG_ENABLE([unversioned-libpng-pc],
+ AS_HELP_STRING([[[--enable-unversioned-libpng-pc]]],
+ [Install the configuration file 'libpng.pc' as a link to the versioned]
+ [version. This is done by default - use --disable-unversioned-libpng-pc]
+ [to change this.]))
+AM_CONDITIONAL([DO_INSTALL_LIBPNG_PC],
+ [test "$enable_unversioned_libpng_pc" != "no"])
+
+AC_ARG_ENABLE([unversioned-libpng-config],
+ AS_HELP_STRING([[[--enable-unversioned-libpng-config]]],
+ [Install the configuration file 'libpng-config' as a link to the]
+ [versioned version. This is done by default - use]
+ [--disable-unversioned-libpng-config to change this.]))
+AM_CONDITIONAL([DO_INSTALL_LIBPNG_CONFIG],
+ [test "$enable_unversioned_libpng_config" != "no"])
+
+# HOST SPECIFIC OPTIONS
+# =====================
+#
+# ARM
+# ===
+#
+# ARM NEON (SIMD) support.
+
+AC_ARG_ENABLE([arm-neon],
+ AS_HELP_STRING([[[--enable-arm-neon]]],
+ [Enable ARM NEON optimizations: =no/off, check, api, yes/on:]
+ [no/off: disable the optimizations; check: use internal checking code]
+ [(deprecated and poorly supported); api: disable by default, enable by]
+ [a call to png_set_option; yes/on: turn on unconditionally.]
+ [If not specified: determined by the compiler.]),
+ [case "$enableval" in
+ no|off)
+ # disable the default enabling on __ARM_NEON__ systems:
+ AC_DEFINE([PNG_ARM_NEON_OPT], [0],
+ [Disable ARM Neon optimizations])
+ # Prevent inclusion of the assembler files below:
+ enable_arm_neon=no;;
+ check)
+ AC_DEFINE([PNG_ARM_NEON_CHECK_SUPPORTED], [],
+ [Check for ARM Neon support at run-time]);;
+ api)
+ AC_DEFINE([PNG_ARM_NEON_API_SUPPORTED], [],
+ [Turn on ARM Neon optimizations at run-time]);;
+ yes|on)
+ AC_DEFINE([PNG_ARM_NEON_OPT], [2],
+ [Enable ARM Neon optimizations])
+ AC_MSG_WARN([--enable-arm-neon: please specify 'check' or 'api', if]
+ [you want the optimizations unconditionally pass -mfpu=neon]
+ [to the compiler.]);;
+ *)
+ AC_MSG_ERROR([--enable-arm-neon=${enable_arm_neon}: invalid value])
+ esac])
+
+# Add ARM specific files to all builds where the host_cpu is arm ('arm*') or
+# where ARM optimizations were explicitly requested (this allows a fallback if a
+# future host CPU does not match 'arm*')
+
+AM_CONDITIONAL([PNG_ARM_NEON],
+ [test "$enable_arm_neon" != 'no' &&
+ case "$host_cpu" in
+ arm*|aarch64*) :;;
+ *) test "$enable_arm_neon" != '';;
+ esac])
+
+AC_MSG_NOTICE([[Extra options for compiler: $PNG_COPTS]])
+
+# Config files, substituting as above
+AC_CONFIG_FILES([Makefile libpng.pc:libpng.pc.in])
+AC_CONFIG_FILES([libpng-config:libpng-config.in],
+ [chmod +x libpng-config])
+
+AC_OUTPUT
diff --git a/libpng/contrib/README.txt b/libpng/contrib/README.txt
new file mode 100644
index 0000000..97963c6
--- /dev/null
+++ b/libpng/contrib/README.txt
@@ -0,0 +1,5 @@
+
+This "contrib" directory contains contributions which are not necessarily under
+the libpng license, although all are open source. They are not part of
+libpng proper and are not used for building the library, although some are used
+for testing the library via "make check".
diff --git a/libpng/contrib/arm-neon/README b/libpng/contrib/arm-neon/README
new file mode 100644
index 0000000..b4248cf
--- /dev/null
+++ b/libpng/contrib/arm-neon/README
@@ -0,0 +1,83 @@
+OPERATING SYSTEM SPECIFIC ARM NEON DETECTION
+--------------------------------------------
+
+Detection of the ability to execute ARM NEON on an ARM processor requires
+operating system support. (The information is not available in user mode.)
+
+HOW TO USE THIS
+---------------
+
+This directory contains C code fragments that can be included in arm/arm_init.c
+by setting the macro PNG_ARM_NEON_FILE to the file name in "" or <> at build
+time. This setting is not recorded in pnglibconf.h and can be changed simply by
+rebuilding arm/arm_init.o with the required macro definition.
+
+For any of this code to be used the ARM NEON code must be enabled and run time
+checks must be supported. I.e.:
+
+#if PNG_ARM_NEON_OPT > 0
+#ifdef PNG_ARM_NEON_CHECK_SUPPORTED
+
+This is done in a 'configure' build by passing configure the argument:
+
+ --enable-arm-neon=check
+
+Apart from the basic Linux implementation in contrib/arm-neon/linux.c this code
+is unsupported. That means that it is not even compiled on a regular basis and
+may be broken in any given minor release.
+
+FILE FORMAT
+-----------
+
+Each file documents its testing status as of the last time it was tested (which
+may have been a long time ago):
+
+STATUS: one of:
+ SUPPORTED: This indicates that the file is included in the regularly
+ performed test builds and bugs are fixed when discovered.
+ COMPILED: This indicates that the code did compile at least once. See the
+ more detailed description for the extent to which the result was
+ successful.
+ TESTED: This means the code was fully compiled into the libpng test programs
+ and these were run at least once.
+
+BUG REPORTS: an email address to which to send reports of problems
+
+The file is a fragment of C code. It should not define any 'extern' symbols;
+everything should be static. It must define the function:
+
+static int png_have_neon(png_structp png_ptr);
+
+That function must return 1 if ARM NEON instructions are supported, 0 if not.
+It must not execute png_error unless it detects a bug. A png_error will prevent
+the reading of the PNG and in the future, writing too.
+
+BUG REPORTS
+-----------
+
+If you mail a bug report for any file that is not SUPPORTED there may only be
+limited response. Consider fixing it and sending a patch to fix the problem -
+this is more likely to result in action.
+
+CONTRIBUTIONS
+-------------
+
+You may send contributions of new implementations to
+png-mng-implement@sourceforge.net. Please write code in strict C90 C where
+possible. Obviously OS dependencies are to be expected. If you submit code you
+must have the authors permission and it must have a license that is acceptable
+to the current maintainer; in particular that license must permit modification
+and redistribution.
+
+Please try to make the contribution a single file and give the file a clear and
+unambiguous name that identifies the target OS. If multiple files really are
+required put them all in a sub-directory.
+
+You must also be prepared to handle bug reports from users of the code, either
+by joining the png-mng-implement mailing list or by providing an email for the
+"BUG REPORTS" entry or both. Please make sure that the header of the file
+contains the STATUS and BUG REPORTS fields as above.
+
+Please list the OS requirements as precisely as possible. Ideally you should
+also list the environment in which the code has been tested and certainly list
+any environments where you suspect it might not work.
diff --git a/libpng/contrib/arm-neon/android-ndk.c b/libpng/contrib/arm-neon/android-ndk.c
new file mode 100644
index 0000000..7240123
--- /dev/null
+++ b/libpng/contrib/arm-neon/android-ndk.c
@@ -0,0 +1,39 @@
+/* contrib/arm-neon/android-ndk.c
+ *
+ * Copyright (c) 2014 Glenn Randers-Pehrson
+ * Written by John Bowler, 2014.
+ * Last changed in libpng 1.6.10 [March 6, 2014]
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * SEE contrib/arm-neon/README before reporting bugs
+ *
+ * STATUS: COMPILED, UNTESTED
+ * BUG REPORTS: png-mng-implement@sourceforge.net
+ *
+ * png_have_neon implemented for the Android NDK, see:
+ *
+ * Documentation:
+ * http://www.kandroid.org/ndk/docs/CPU-ARM-NEON.html
+ * http://code.google.com/p/android/issues/detail?id=49065
+ *
+ * NOTE: this requires that libpng is built against the Android NDK and linked
+ * with an implementation of the Android ARM 'cpu-features' library. The code
+ * has been compiled only, not linked: no version of the library has been found,
+ * only the header files exist in the NDK.
+ */
+#include <cpu-features.h>
+
+static int
+png_have_neon(png_structp png_ptr)
+{
+ /* This is a whole lot easier than the linux code, however it is probably
+ * implemented as below, therefore it is better to cache the result (these
+ * function calls may be slow!)
+ */
+ PNG_UNUSED(png_ptr)
+ return android_getCpuFamily() == ANDROID_CPU_FAMILY_ARM &&
+ (android_getCpuFeatures() & ANDROID_CPU_ARM_FEATURE_NEON) != 0;
+}
diff --git a/libpng/contrib/arm-neon/linux-auxv.c b/libpng/contrib/arm-neon/linux-auxv.c
new file mode 100644
index 0000000..4d26bd3
--- /dev/null
+++ b/libpng/contrib/arm-neon/linux-auxv.c
@@ -0,0 +1,120 @@
+/* contrib/arm-neon/linux-auxv.c
+ *
+ * Copyright (c) 2014 Glenn Randers-Pehrson
+ * Written by Mans Rullgard, 2011.
+ * Last changed in libpng 1.6.10 [March 6, 2014]
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * SEE contrib/arm-neon/README before reporting bugs
+ *
+ * STATUS: COMPILED, TESTED
+ * BUG REPORTS: png-mng-implement@sourceforge.net
+ *
+ * png_have_neon implemented for Linux versions which allow access to
+ * /proc/self/auxv. This is probably faster, cleaner and safer than the code to
+ * read /proc/cpuinfo in contrib/arm-neon/linux, however it is yet another piece
+ * of potentially untested code and has more complex dependencies than the code
+ * to read cpuinfo.
+ *
+ * This generic __linux__ implementation requires reading /proc/self/auxv and
+ * looking at each element for one that records NEON capabilities.
+ */
+#include <unistd.h> /* for POSIX 1003.1 */
+#include <errno.h> /* for EINTR */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <elf.h>
+#include <asm/hwcap.h>
+
+/* A read call may be interrupted, in which case it returns -1 and sets errno to
+ * EINTR if nothing was done, otherwise (if something was done) a partial read
+ * may result.
+ */
+static size_t
+safe_read(png_structp png_ptr, int fd, void *buffer_in, size_t nbytes)
+{
+ size_t ntotal = 0;
+ char *buffer = png_voidcast(char*, buffer_in);
+
+ while (nbytes > 0)
+ {
+ unsigned int nread;
+ int iread;
+
+ /* Passing nread > INT_MAX to read is implementation defined in POSIX
+ * 1003.1, therefore despite the unsigned argument portable code must
+ * limit the value to INT_MAX!
+ */
+ if (nbytes > INT_MAX)
+ nread = INT_MAX;
+
+ else
+ nread = (unsigned int)/*SAFE*/nbytes;
+
+ iread = read(fd, buffer, nread);
+
+ if (iread == -1)
+ {
+ /* This is the devil in the details, a read can terminate early with 0
+ * bytes read because of EINTR, yet it still returns -1 otherwise end
+ * of file cannot be distinguished.
+ */
+ if (errno != EINTR)
+ {
+ png_warning(png_ptr, "/proc read failed");
+ return 0; /* I.e., a permanent failure */
+ }
+ }
+
+ else if (iread < 0)
+ {
+ /* Not a valid 'read' result: */
+ png_warning(png_ptr, "OS /proc read bug");
+ return 0;
+ }
+
+ else if (iread > 0)
+ {
+ /* Continue reading until a permanent failure, or EOF */
+ buffer += iread;
+ nbytes -= (unsigned int)/*SAFE*/iread;
+ ntotal += (unsigned int)/*SAFE*/iread;
+ }
+
+ else
+ return ntotal;
+ }
+
+ return ntotal; /* nbytes == 0 */
+}
+
+static int
+png_have_neon(png_structp png_ptr)
+{
+ int fd = open("/proc/self/auxv", O_RDONLY);
+ Elf32_auxv_t aux;
+
+ /* Failsafe: failure to open means no NEON */
+ if (fd == -1)
+ {
+ png_warning(png_ptr, "/proc/self/auxv open failed");
+ return 0;
+ }
+
+ while (safe_read(png_ptr, fd, &aux, sizeof aux) == sizeof aux)
+ {
+ if (aux.a_type == AT_HWCAP && (aux.a_un.a_val & HWCAP_NEON) != 0)
+ {
+ close(fd);
+ return 1;
+ }
+ }
+
+ close(fd);
+ return 0;
+}
diff --git a/libpng/contrib/arm-neon/linux.c b/libpng/contrib/arm-neon/linux.c
new file mode 100644
index 0000000..94f9bb1
--- /dev/null
+++ b/libpng/contrib/arm-neon/linux.c
@@ -0,0 +1,161 @@
+/* contrib/arm-neon/linux.c
+ *
+ * Copyright (c) 2014 Glenn Randers-Pehrson
+ * Written by John Bowler, 2014.
+ * Last changed in libpng 1.6.16 [December 22, 2014]
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * SEE contrib/arm-neon/README before reporting bugs
+ *
+ * STATUS: SUPPORTED
+ * BUG REPORTS: png-mng-implement@sourceforge.net
+ *
+ * png_have_neon implemented for Linux by reading the widely available
+ * pseudo-file /proc/cpuinfo.
+ *
+ * This code is strict ANSI-C and is probably moderately portable; it does
+ * however use <stdio.h> and it assumes that /proc/cpuinfo is never localized.
+ */
+#include <stdio.h>
+
+static int
+png_have_neon(png_structp png_ptr)
+{
+ FILE *f = fopen("/proc/cpuinfo", "rb");
+
+ if (f != NULL)
+ {
+ /* This is a simple state machine which reads the input byte-by-byte until
+ * it gets a match on the 'neon' feature or reaches the end of the stream.
+ */
+ static const char ch_feature[] = { 70, 69, 65, 84, 85, 82, 69, 83 };
+ static const char ch_neon[] = { 78, 69, 79, 78 };
+
+ enum
+ {
+ StartLine, Feature, Colon, StartTag, Neon, HaveNeon, SkipTag, SkipLine
+ } state;
+ int counter;
+
+ for (state=StartLine, counter=0;;)
+ {
+ int ch = fgetc(f);
+
+ if (ch == EOF)
+ {
+ /* EOF means error or end-of-file, return false; neon at EOF is
+ * assumed to be a mistake.
+ */
+ fclose(f);
+ return 0;
+ }
+
+ switch (state)
+ {
+ case StartLine:
+ /* Match spaces at the start of line */
+ if (ch <= 32) /* skip control characters and space */
+ break;
+
+ counter=0;
+ state = Feature;
+ /* FALL THROUGH */
+
+ case Feature:
+ /* Match 'FEATURE', ASCII case insensitive. */
+ if ((ch & ~0x20) == ch_feature[counter])
+ {
+ if (++counter == (sizeof ch_feature))
+ state = Colon;
+ break;
+ }
+
+ /* did not match 'feature' */
+ state = SkipLine;
+ /* FALL THROUGH */
+
+ case SkipLine:
+ skipLine:
+ /* Skip everything until we see linefeed or carriage return */
+ if (ch != 10 && ch != 13)
+ break;
+
+ state = StartLine;
+ break;
+
+ case Colon:
+ /* Match any number of space or tab followed by ':' */
+ if (ch == 32 || ch == 9)
+ break;
+
+ if (ch == 58) /* i.e. ':' */
+ {
+ state = StartTag;
+ break;
+ }
+
+ /* Either a bad line format or a 'feature' prefix followed by
+ * other characters.
+ */
+ state = SkipLine;
+ goto skipLine;
+
+ case StartTag:
+ /* Skip space characters before a tag */
+ if (ch == 32 || ch == 9)
+ break;
+
+ state = Neon;
+ counter = 0;
+ /* FALL THROUGH */
+
+ case Neon:
+ /* Look for 'neon' tag */
+ if ((ch & ~0x20) == ch_neon[counter])
+ {
+ if (++counter == (sizeof ch_neon))
+ state = HaveNeon;
+ break;
+ }
+
+ state = SkipTag;
+ /* FALL THROUGH */
+
+ case SkipTag:
+ /* Skip non-space characters */
+ if (ch == 10 || ch == 13)
+ state = StartLine;
+
+ else if (ch == 32 || ch == 9)
+ state = StartTag;
+ break;
+
+ case HaveNeon:
+ /* Have seen a 'neon' prefix, but there must be a space or new
+ * line character to terminate it.
+ */
+ if (ch == 10 || ch == 13 || ch == 32 || ch == 9)
+ {
+ fclose(f);
+ return 1;
+ }
+
+ state = SkipTag;
+ break;
+
+ default:
+ png_error(png_ptr, "png_have_neon: internal error (bug)");
+ }
+ }
+ }
+
+#ifdef PNG_WARNINGS_SUPPORTED
+ else
+ png_warning(png_ptr, "/proc/cpuinfo open failed");
+#endif
+
+ return 0;
+}
diff --git a/libpng/contrib/conftest/README b/libpng/contrib/conftest/README
new file mode 100644
index 0000000..0f47279
--- /dev/null
+++ b/libpng/contrib/conftest/README
@@ -0,0 +1,49 @@
+This directory contains test configuration files, currently always '.dfa' files
+intended to be used in the build by setting the make macro DFA_XTRA to the name
+of the file.
+
+These files are used in release validation of the 'configure' builds of libpng
+by building 'make check', or 'make all-am' for cross-builds, with each .dfa
+file.
+
+The files in this directory may change between minor releases, however
+contributions describing specific builds of libpng are welcomed. There is no
+guarantee that libpng will continue to build with such configurations; support
+for given configurations can be, and has been, dropped between successive minor
+releases. However if a .dfa file describing a configuration is not in this
+directory it is very unlikely that it will be tested before a minor release!
+
+You can use these .dfa files as the basis of new configurations. Files in this
+directory should not have any use restrictions or restrictive licenses.
+
+This directory is not included in the .zip and .7z distributions, which do
+not contain 'configure' scripts.
+
+DOCUMENTATION
+=============
+
+Examples:
+ ${srcdir}/pngusr.dfa
+ ${srcdir}/contrib/pngminim/*/pngusr.dfa
+
+Documentation of the options:
+ ${srcdir}/scripts/pnglibconf.dfa
+
+Documentation of the file format:
+ ${srcdir}/scripts/options.awk
+
+FILE NAMING
+===========
+
+File names in this directory may NOT contain any of the five characters:
+
+ - , + * ?
+
+Neither may they contain any space character.
+
+While other characters may be used it is strongly suggested that file names be
+limited to lower case Latiin alphabetic characters (a-z), digits (0-9) and, if
+necessary the underscore (_) character. File names should be about 8 characters
+long (excluding the .dfa extension). Submitted .dfa files should have names
+between 7 and 16 characters long, shorter names (6 characters or less) are
+reserved for standard tests.
diff --git a/libpng/contrib/conftest/read.dfa b/libpng/contrib/conftest/read.dfa
new file mode 100644
index 0000000..21e88d0
--- /dev/null
+++ b/libpng/contrib/conftest/read.dfa
@@ -0,0 +1,58 @@
+# read.dfa
+# Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2013
+# Usage rights:
+# To the extent possible under law, the author has waived all copyright and
+# related or neighboring rights to this work. This work is published from:
+# United States.
+#
+# Build libpng with basic read support. This enables the lowest level libpng
+# read API - the one where the calling code has to use a loop to read each row.
+# At present this is the API used by most programs.
+#
+# Support is enabled only for those chunks and transformations that are
+# typically required - others can be added easily.
+#
+
+everything = off
+
+# The sequential read code is enabled here; the progressive code can be used
+# instead but there is no point enabling both.
+
+option SEQUENTIAL_READ on
+
+# Likewise it is pointless enabling both fixed and floating point APIs. Choose
+# one or the other for both the API and the internal math.
+
+#Fixed point:
+#option FIXED_POINT on
+#option FLOATING_ARITHMETIC off
+
+#Floating point:
+option FLOATING_POINT on
+option FLOATING_ARITHMETIC on
+
+# Basic error handling, IO and user memory support. The latter allows the
+# application program to provide its own implementations of 'malloc' and 'free'.
+option SETJMP on
+option STDIO on
+option USER_MEM on
+
+# To read the full set of PNG images correctly interlace, transparency and
+# 16-bit support is required. The application can implement interlace itself,
+# but very few do and it's no longer possible to disable it when READ is
+# enabled.
+option READ_tRNS on
+option READ_16BIT on
+
+# Everything else is application dependent. This file assumes the app handles
+# all the native PNG bit layouts, so it doesn't need any of layout change
+# transforms, but needs libpng to perform gamma correction. It doesn't do any
+# colorspace stuff and ignores the 'significant bit' information.
+#
+# If your app always expands the image to a limited set of bit layouts you
+# probably want to consider using the simplified API instead of the low level
+# one - see png.h and s_read.dfa.
+option READ_GAMMA on
diff --git a/libpng/contrib/conftest/s_read.dfa b/libpng/contrib/conftest/s_read.dfa
new file mode 100644
index 0000000..cb1ce0b
--- /dev/null
+++ b/libpng/contrib/conftest/s_read.dfa
@@ -0,0 +1,35 @@
+# s_read.dfa
+# Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2013
+# Usage rights:
+# To the extent possible under law, the author has waived all copyright and
+# related or neighboring rights to this work. This work is published from:
+# United States.
+#
+# Build libpng with simplified read support (only). This builds a minimal
+# libpng able to read all PNG formats and convert them into a small number of
+# well understood memory formats.
+#
+
+everything = off
+
+option SIMPLIFIED_READ on
+
+# It isn't necessary to chose fixed or floating point for the APIs because the
+# simplified API doesn't need fixed or floating point numbers. It is necessary
+# to chose an internal math implementation. The default (because of 'everything
+# = off') is fixed point - turn the floating point implementation on if you have
+# hardware floating point or prefer your software floating point implementation.
+option FLOATING_ARITHMETIC on
+
+# This is not strictly necessary, but without it the message strings in the API
+# will not be filled in
+option ERROR_TEXT on
+
+# Switching these options on enables the 'AFIRST' and 'BGR' formats - you don't
+# need this if you don't use them, they just allow the in-memory layout to be
+# changed to match common hardware formats.
+option SIMPLIFIED_READ_AFIRST on
+option SIMPLIFIED_READ_BGR on
diff --git a/libpng/contrib/conftest/s_write.dfa b/libpng/contrib/conftest/s_write.dfa
new file mode 100644
index 0000000..e540a46
--- /dev/null
+++ b/libpng/contrib/conftest/s_write.dfa
@@ -0,0 +1,33 @@
+# s_write.dfa
+# Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2013
+# Usage rights:
+# To the extent possible under law, the author has waived all copyright and
+# related or neighboring rights to this work. This work is published from:
+# United States.
+#
+# Build libpng with (just) simplified write support
+#
+
+everything = off
+
+option SIMPLIFIED_WRITE on
+
+# It isn't necessary to chose fixed or floating point for the APIs because the
+# simplified API doesn't need fixed or floating point numbers. It is necessary
+# to chose an internal math implementation. The default (because of 'everything
+# = off') is fixed point - turn the floating point implementation on if you have
+# hardware floating point or prefer your software floating point implementation.
+option FLOATING_ARITHMETIC on
+
+# This is not strictly necessary, but without it the message strings in the API
+# will not be filled in
+option ERROR_TEXT on
+
+# Switching these options on enables the 'AFIRST' and 'BGR' formats - you don't
+# need this if you don't use them, they just allow the in-memory layout to be
+# changed to match common hardware formats.
+option SIMPLIFIED_WRITE_AFIRST on
+option SIMPLIFIED_WRITE_BGR on
diff --git a/libpng/contrib/conftest/simple.dfa b/libpng/contrib/conftest/simple.dfa
new file mode 100644
index 0000000..0419333
--- /dev/null
+++ b/libpng/contrib/conftest/simple.dfa
@@ -0,0 +1,36 @@
+# simple.dfa
+# Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2013
+# Usage rights:
+# To the extent possible under law, the author has waived all copyright and
+# related or neighboring rights to this work. This work is published from:
+# United States.
+#
+# Build libpng with just the simplified APIs (read and write).
+#
+
+everything = off
+
+option SIMPLIFIED_WRITE on
+option SIMPLIFIED_READ on
+
+# It isn't necessary to chose fixed or floating point for the APIs because the
+# simplified API doesn't need fixed or floating point numbers. It is necessary
+# to chose an internal math implementation. The default (because of 'everything
+# = off') is fixed point - turn the floating point implementation on if you have
+# hardware floating point or prefer your software floating point implementation.
+option FLOATING_ARITHMETIC on
+
+# This is not strictly necessary, but without it the message strings in the API
+# will not be filled in
+option ERROR_TEXT on
+
+# Switching these options on enables the 'AFIRST' and 'BGR' formats - you don't
+# need this if you don't use them, they just allow the in-memory layout to be
+# changed to match common hardware formats.
+option SIMPLIFIED_READ_AFIRST on
+option SIMPLIFIED_READ_BGR on
+option SIMPLIFIED_WRITE_AFIRST on
+option SIMPLIFIED_WRITE_BGR on
diff --git a/libpng/contrib/conftest/write.dfa b/libpng/contrib/conftest/write.dfa
new file mode 100644
index 0000000..3319aab
--- /dev/null
+++ b/libpng/contrib/conftest/write.dfa
@@ -0,0 +1,45 @@
+# write.dfa
+# Build time configuration of libpng
+#
+# Author: John Bowler
+# Copyright: (c) John Bowler, 2013
+# Usage rights:
+# To the extent possible under law, the author has waived all copyright and
+# related or neighboring rights to this work. This work is published from:
+# United States.
+#
+# Build libpng with no read support and minimal write support.
+#
+
+everything = off
+
+# Switch on the write code - this makes a minimalist encoder
+
+option WRITE on
+
+# Choose fixed or floating point APIs and arithmetic. The choices are
+# independent but normally they will match. It is typically better to use the
+# floating point if you have floating point hardware. If you don't know, or
+# (perhaps) to make libpng smaller used fixed point throughout.
+
+#Fixed point:
+#option FIXED_POINT on
+#option FLOATING_ARITHMETIC off
+
+#Floating point:
+option FLOATING_POINT on
+option FLOATING_ARITHMETIC on
+
+# Basic error handling, IO and user memory support. The latter allows the
+# application program to provide its own implementations of 'malloc' and 'free'.
+option SETJMP on
+option STDIO on
+option USER_MEM on
+
+# Everything else is optional. Unlike the read code in libpng the write code
+# does not need to deal with arbitrary formats, so only add support for things
+# you really do write! For example you might only write sRGB images, sometimes
+# with transparency and never write 16 bit images, so:
+option WRITE_sRGB on
+option WRITE_tRNS on
+#option WRITE_16BIT off (this is the default with 'everything = off')
diff --git a/libpng/contrib/examples/README.txt b/libpng/contrib/examples/README.txt
new file mode 100644
index 0000000..0525c9d
--- /dev/null
+++ b/libpng/contrib/examples/README.txt
@@ -0,0 +1,24 @@
+
+This directory (contrib/examples) contains examples of libpng usage.
+
+NO COPYRIGHT RIGHTS ARE CLAIMED TO ANY OF THE FILES IN THIS DIRECTORY.
+
+To the extent possible under law, the authors have waived all copyright and
+related or neighboring rights to this work. This work is published from:
+United States.
+
+The files may be used freely in any way. The intention is that appropriate
+parts of the files be used in other libpng-using programs without any need for
+the authors of the using code to seek copyright or license from the original
+authors.
+
+The source code and comments in this directory are the original work of the
+people named below. No other person or organization has made contributions to
+the work in this directory.
+
+ORIGINAL AUTHORS
+ The following people have contributed to the code in this directory. None
+ of the people below claim any rights with regard to the contents of this
+ directory.
+
+ John Bowler <jbowler@acm.org>
diff --git a/libpng/contrib/examples/iccfrompng.c b/libpng/contrib/examples/iccfrompng.c
new file mode 100644
index 0000000..603037e
--- /dev/null
+++ b/libpng/contrib/examples/iccfrompng.c
@@ -0,0 +1,185 @@
+/*- iccfrompng
+ *
+ * COPYRIGHT: Written by John Cunningham Bowler, 2011.
+ * To the extent possible under law, the author has waived all copyright and
+ * related or neighboring rights to this work. This work is published from:
+ * United States.
+ *
+ * Extract any icc profiles found in the given PNG files. This is a simple
+ * example of a program that extracts information from the header of a PNG file
+ * without processing the image. Notice that some header information may occur
+ * after the image data. Textual data and comments are an example; the approach
+ * in this file won't work reliably for such data because it only looks for the
+ * information in the section of the file that preceeds the image data.
+ *
+ * Compile and link against libpng and zlib, plus anything else required on the
+ * system you use.
+ *
+ * To use supply a list of PNG files containing iCCP chunks, the chunks will be
+ * extracted to a similarly named file with the extension replaced by 'icc',
+ * which will be overwritten without warning.
+ */
+#include <stdlib.h>
+#include <setjmp.h>
+#include <string.h>
+#include <stdio.h>
+
+#include <png.h>
+
+#if defined(PNG_READ_SUPPORTED) && defined(PNG_STDIO_SUPPORTED) && \
+ defined (PNG_iCCP_SUPPORTED)
+
+
+static int verbose = 1;
+static png_byte no_profile[] = "no profile";
+
+static png_bytep
+extract(FILE *fp, png_uint_32 *proflen)
+{
+ png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,0,0,0);
+ png_infop info_ptr = NULL;
+ png_bytep result = NULL;
+
+ /* Initialize for error or no profile: */
+ *proflen = 0;
+
+ if (png_ptr == NULL)
+ {
+ fprintf(stderr, "iccfrompng: version library mismatch?\n");
+ return 0;
+ }
+
+ if (setjmp(png_jmpbuf(png_ptr)))
+ {
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+ return 0;
+ }
+
+ png_init_io(png_ptr, fp);
+
+ info_ptr = png_create_info_struct(png_ptr);
+ if (info_ptr == NULL)
+ png_error(png_ptr, "OOM allocating info structure");
+
+ png_read_info(png_ptr, info_ptr);
+
+ {
+ png_charp name;
+ int compression_type;
+ png_bytep profile;
+
+ if (png_get_iCCP(png_ptr, info_ptr, &name, &compression_type, &profile,
+ proflen) & PNG_INFO_iCCP)
+ {
+ result = malloc(*proflen);
+ if (result != NULL)
+ memcpy(result, profile, *proflen);
+
+ else
+ png_error(png_ptr, "OOM allocating profile buffer");
+ }
+
+ else
+ result = no_profile;
+ }
+
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+ return result;
+}
+
+static int
+extract_one_file(const char *filename)
+{
+ int result = 0;
+ FILE *fp = fopen(filename, "rb");
+
+ if (fp != NULL)
+ {
+ png_uint_32 proflen = 0;
+ png_bytep profile = extract(fp, &proflen);
+
+ if (profile != NULL && profile != no_profile)
+ {
+ size_t len;
+ char *output;
+
+ {
+ const char *ep = strrchr(filename, '.');
+
+ if (ep != NULL)
+ len = ep-filename;
+
+ else
+ len = strlen(filename);
+ }
+
+ output = malloc(len + 5);
+ if (output != NULL)
+ {
+ FILE *of;
+
+ memcpy(output, filename, len);
+ strcpy(output+len, ".icc");
+
+ of = fopen(output, "wb");
+ if (of != NULL)
+ {
+ if (fwrite(profile, proflen, 1, of) == 1 &&
+ fflush(of) == 0 &&
+ fclose(of) == 0)
+ {
+ if (verbose)
+ printf("%s -> %s\n", filename, output);
+ /* Success return */
+ result = 1;
+ }
+
+ else
+ {
+ fprintf(stderr, "%s: error writing profile\n", output);
+ if (remove(output))
+ fprintf(stderr, "%s: could not remove file\n", output);
+ }
+ }
+
+ else
+ fprintf(stderr, "%s: failed to open output file\n", output);
+
+ free(output);
+ }
+
+ else
+ fprintf(stderr, "%s: OOM allocating string!\n", filename);
+
+ free(profile);
+ }
+
+ else if (verbose && profile == no_profile)
+ printf("%s has no profile\n", filename);
+ }
+
+ else
+ fprintf(stderr, "%s: could not open file\n", filename);
+
+ return result;
+}
+
+int
+main(int argc, char **argv)
+{
+ int i;
+ int extracted = 0;
+
+ for (i=1; i<argc; ++i)
+ {
+ if (strcmp(argv[i], "-q") == 0)
+ verbose = 0;
+
+ else if (extract_one_file(argv[i]))
+ extracted = 1;
+ }
+
+ /* Exit code is true if any extract succeeds */
+ return extracted == 0;
+}
+#endif /* READ && STDIO && iCCP */
diff --git a/libpng/contrib/examples/pngpixel.c b/libpng/contrib/examples/pngpixel.c
new file mode 100644
index 0000000..f762379
--- /dev/null
+++ b/libpng/contrib/examples/pngpixel.c
@@ -0,0 +1,371 @@
+/*- pngpixel
+ *
+ * COPYRIGHT: Written by John Cunningham Bowler, 2011.
+ * To the extent possible under law, the author has waived all copyright and
+ * related or neighboring rights to this work. This work is published from:
+ * United States.
+ *
+ * Read a single pixel value from a PNG file.
+ *
+ * This code illustrates basic 'by-row' reading of a PNG file using libpng.
+ * Rows are read until a particular pixel is found; the value of this pixel is
+ * then printed on stdout.
+ *
+ * The code illustrates how to do this on interlaced as well as non-interlaced
+ * images. Normally you would call png_set_interlace_handling() to have libpng
+ * deal with the interlace for you, but that obliges you to buffer half of the
+ * image to assemble the interlaced rows. In this code
+ * png_set_interlace_handling() is not called and, instead, the code handles the
+ * interlace passes directly looking for the required pixel.
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <setjmp.h> /* required for error handling */
+
+/* Normally use <png.h> here to get the installed libpng, but this is done to
+ * ensure the code picks up the local libpng implementation:
+ */
+#include "../../png.h"
+
+#if defined(PNG_READ_SUPPORTED) && defined(PNG_SEQUENTIAL_READ_SUPPORTED)
+
+/* Return component 'c' of pixel 'x' from the given row. */
+static unsigned int
+component(png_const_bytep row, png_uint_32 x, unsigned int c,
+ unsigned int bit_depth, unsigned int channels)
+{
+ /* PNG images can be up to 2^31 pixels wide, but this means they can be up to
+ * 2^37 bits wide (for a 64-bit pixel - the largest possible) and hence 2^34
+ * bytes wide. Since the row fitted into memory, however, the following must
+ * work:
+ */
+ png_uint_32 bit_offset_hi = bit_depth * ((x >> 6) * channels);
+ png_uint_32 bit_offset_lo = bit_depth * ((x & 0x3f) * channels + c);
+
+ row = (png_const_bytep)(((PNG_CONST png_byte (*)[8])row) + bit_offset_hi);
+ row += bit_offset_lo >> 3;
+ bit_offset_lo &= 0x07;
+
+ /* PNG pixels are packed into bytes to put the first pixel in the highest
+ * bits of the byte and into two bytes for 16-bit values with the high 8 bits
+ * first, so:
+ */
+ switch (bit_depth)
+ {
+ case 1: return (row[0] >> (7-bit_offset_lo)) & 0x01;
+ case 2: return (row[0] >> (6-bit_offset_lo)) & 0x03;
+ case 4: return (row[0] >> (4-bit_offset_lo)) & 0x0f;
+ case 8: return row[0];
+ case 16: return (row[0] << 8) + row[1];
+ default:
+ /* This should never happen; it indicates a bug in this program or in
+ * libpng itself:
+ */
+ fprintf(stderr, "pngpixel: invalid bit depth %u\n", bit_depth);
+ exit(1);
+ }
+}
+
+/* Print a pixel from a row returned by libpng; determine the row format, find
+ * the pixel, and print the relevant information to stdout.
+ */
+static void
+print_pixel(png_structp png_ptr, png_infop info_ptr, png_const_bytep row,
+ png_uint_32 x)
+{
+ PNG_CONST unsigned int bit_depth = png_get_bit_depth(png_ptr, info_ptr);
+
+ switch (png_get_color_type(png_ptr, info_ptr))
+ {
+ case PNG_COLOR_TYPE_GRAY:
+ printf("GRAY %u\n", component(row, x, 0, bit_depth, 1));
+ return;
+
+ /* The palette case is slightly more difficult - the palette and, if
+ * present, the tRNS ('transparency', though the values are really
+ * opacity) data must be read to give the full picture:
+ */
+ case PNG_COLOR_TYPE_PALETTE:
+ {
+ PNG_CONST int index = component(row, x, 0, bit_depth, 1);
+ png_colorp palette = NULL;
+ int num_palette = 0;
+
+ if ((png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette) &
+ PNG_INFO_PLTE) && num_palette > 0 && palette != NULL)
+ {
+ png_bytep trans_alpha = NULL;
+ int num_trans = 0;
+ if ((png_get_tRNS(png_ptr, info_ptr, &trans_alpha, &num_trans,
+ NULL) & PNG_INFO_tRNS) && num_trans > 0 &&
+ trans_alpha != NULL)
+ printf("INDEXED %u = %d %d %d %d\n", index,
+ palette[index].red, palette[index].green,
+ palette[index].blue,
+ index < num_trans ? trans_alpha[index] : 255);
+
+ else /* no transparency */
+ printf("INDEXED %u = %d %d %d\n", index,
+ palette[index].red, palette[index].green,
+ palette[index].blue);
+ }
+
+ else
+ printf("INDEXED %u = invalid index\n", index);
+ }
+ return;
+
+ case PNG_COLOR_TYPE_RGB:
+ printf("RGB %u %u %u\n", component(row, x, 0, bit_depth, 3),
+ component(row, x, 1, bit_depth, 3),
+ component(row, x, 2, bit_depth, 3));
+ return;
+
+ case PNG_COLOR_TYPE_GRAY_ALPHA:
+ printf("GRAY+ALPHA %u %u\n", component(row, x, 0, bit_depth, 2),
+ component(row, x, 1, bit_depth, 2));
+ return;
+
+ case PNG_COLOR_TYPE_RGB_ALPHA:
+ printf("RGBA %u %u %u %u\n", component(row, x, 0, bit_depth, 4),
+ component(row, x, 1, bit_depth, 4),
+ component(row, x, 2, bit_depth, 4),
+ component(row, x, 3, bit_depth, 4));
+ return;
+
+ default:
+ png_error(png_ptr, "pngpixel: invalid color type");
+ }
+}
+
+int main(int argc, const char **argv)
+{
+ /* This program uses the default, <setjmp.h> based, libpng error handling
+ * mechanism, therefore any local variable that exists before the call to
+ * setjmp and is changed after the call to setjmp returns successfully must
+ * be declared with 'volatile' to ensure that their values don't get
+ * destroyed by longjmp:
+ */
+ volatile int result = 1/*fail*/;
+
+ if (argc == 4)
+ {
+ long x = atol(argv[1]);
+ long y = atol(argv[2]);
+ FILE *f = fopen(argv[3], "rb");
+ volatile png_bytep row = NULL;
+
+ if (f != NULL)
+ {
+ /* libpng requires a callback function for handling errors; this
+ * callback must not return. The default callback function uses a
+ * stored <setjmp.h> style jmp_buf which is held in a png_struct and
+ * writes error messages to stderr. Creating the png_struct is a
+ * little tricky; just copy the following code.
+ */
+ png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
+ NULL, NULL, NULL);
+
+ if (png_ptr != NULL)
+ {
+ png_infop info_ptr = png_create_info_struct(png_ptr);
+
+ if (info_ptr != NULL)
+ {
+ /* Declare stack variables to hold pointers to locally allocated
+ * data.
+ */
+
+ /* Initialize the error control buffer: */
+ if (setjmp(png_jmpbuf(png_ptr)) == 0)
+ {
+ png_uint_32 width, height;
+ int bit_depth, color_type, interlace_method,
+ compression_method, filter_method;
+ png_bytep row_tmp;
+
+ /* Now associate the recently opened (FILE*) with the default
+ * libpng initialization functions. Sometimes libpng is
+ * compiled without stdio support (it can be difficult to do
+ * in some environments); in that case you will have to write
+ * your own read callback to read data from the (FILE*).
+ */
+ png_init_io(png_ptr, f);
+
+ /* And read the first part of the PNG file - the header and
+ * all the information up to the first pixel.
+ */
+ png_read_info(png_ptr, info_ptr);
+
+ /* This fills in enough information to tell us the width of
+ * each row in bytes, allocate the appropriate amount of
+ * space. In this case png_malloc is used - it will not
+ * return if memory isn't available.
+ */
+ row = png_malloc(png_ptr, png_get_rowbytes(png_ptr,
+ info_ptr));
+
+ /* To avoid the overhead of using a volatile auto copy row_tmp
+ * to a local here - just use row for the png_free below.
+ */
+ row_tmp = row;
+
+ /* All the information we need is in the header is returned by
+ * png_get_IHDR, if this fails we can now use 'png_error' to
+ * signal the error and return control to the setjmp above.
+ */
+ if (png_get_IHDR(png_ptr, info_ptr, &width, &height,
+ &bit_depth, &color_type, &interlace_method,
+ &compression_method, &filter_method))
+ {
+ int passes, pass;
+
+ /* png_set_interlace_handling returns the number of
+ * passes required as well as turning on libpng's
+ * handling, but since we do it ourselves this is
+ * necessary:
+ */
+ switch (interlace_method)
+ {
+ case PNG_INTERLACE_NONE:
+ passes = 1;
+ break;
+
+ case PNG_INTERLACE_ADAM7:
+ passes = PNG_INTERLACE_ADAM7_PASSES;
+ break;
+
+ default:
+ png_error(png_ptr, "pngpixel: unknown interlace");
+ }
+
+ /* Now read the pixels, pass-by-pass, row-by-row: */
+ png_start_read_image(png_ptr);
+
+ for (pass=0; pass<passes; ++pass)
+ {
+ png_uint_32 ystart, xstart, ystep, xstep;
+ png_uint_32 py;
+
+ if (interlace_method == PNG_INTERLACE_ADAM7)
+ {
+ /* Sometimes the whole pass is empty because the
+ * image is too narrow or too short. libpng
+ * expects to be called for each row that is
+ * present in the pass, so it may be necessary to
+ * skip the loop below (over py) if the image is
+ * too narrow.
+ */
+ if (PNG_PASS_COLS(width, pass) == 0)
+ continue;
+
+ /* We need the starting pixel and the offset
+ * between each pixel in this pass; use the macros
+ * in png.h:
+ */
+ xstart = PNG_PASS_START_COL(pass);
+ ystart = PNG_PASS_START_ROW(pass);
+ xstep = PNG_PASS_COL_OFFSET(pass);
+ ystep = PNG_PASS_ROW_OFFSET(pass);
+ }
+
+ else
+ {
+ ystart = xstart = 0;
+ ystep = xstep = 1;
+ }
+
+ /* To find the pixel, loop over 'py' for each pass
+ * reading a row and then checking to see if it
+ * contains the pixel.
+ */
+ for (py = ystart; py < height; py += ystep)
+ {
+ png_uint_32 px, ppx;
+
+ /* png_read_row takes two pointers. When libpng
+ * handles the interlace the first is filled in
+ * pixel-by-pixel, and the second receives the same
+ * pixels but they are replicated across the
+ * unwritten pixels so far for each pass. When we
+ * do the interlace, however, they just contain
+ * the pixels from the interlace pass - giving
+ * both is wasteful and pointless, so we pass a
+ * NULL pointer.
+ */
+ png_read_row(png_ptr, row_tmp, NULL);
+
+ /* Now find the pixel if it is in this row; there
+ * are, of course, much better ways of doing this
+ * than using a for loop:
+ */
+ if (y == py) for (px = xstart, ppx = 0;
+ px < width; px += xstep, ++ppx) if (x == px)
+ {
+ /* 'ppx' is the index of the pixel in the row
+ * buffer.
+ */
+ print_pixel(png_ptr, info_ptr, row_tmp, ppx);
+
+ /* Now terminate the loops early - we have
+ * found and handled the required data.
+ */
+ goto pass_loop_end;
+ } /* x loop */
+ } /* y loop */
+ } /* pass loop */
+
+ /* Finally free the temporary buffer: */
+ pass_loop_end:
+ row = NULL;
+ png_free(png_ptr, row_tmp);
+ }
+
+ else
+ png_error(png_ptr, "pngpixel: png_get_IHDR failed");
+
+ }
+
+ else
+ {
+ /* Else libpng has raised an error. An error message has
+ * already been output, so it is only necessary to clean up
+ * locally allocated data:
+ */
+ if (row != NULL)
+ {
+ /* The default implementation of png_free never errors out
+ * (it just crashes if something goes wrong), but the safe
+ * way of using it is still to clear 'row' before calling
+ * png_free:
+ */
+ png_bytep row_tmp = row;
+ row = NULL;
+ png_free(png_ptr, row_tmp);
+ }
+ }
+
+ png_destroy_info_struct(png_ptr, &info_ptr);
+ }
+
+ else
+ fprintf(stderr, "pngpixel: out of memory allocating png_info\n");
+
+ png_destroy_read_struct(&png_ptr, NULL, NULL);
+ }
+
+ else
+ fprintf(stderr, "pngpixel: out of memory allocating png_struct\n");
+ }
+
+ else
+ fprintf(stderr, "pngpixel: %s: could not open file\n", argv[3]);
+ }
+
+ else
+ /* Wrong number of arguments */
+ fprintf(stderr, "pngpixel: usage: pngpixel x y png-file\n");
+
+ return result;
+}
+#endif /* READ && SEQUENTIAL_READ */
diff --git a/libpng/contrib/examples/pngtopng.c b/libpng/contrib/examples/pngtopng.c
new file mode 100644
index 0000000..4acf6b3
--- /dev/null
+++ b/libpng/contrib/examples/pngtopng.c
@@ -0,0 +1,95 @@
+/*- pngtopng
+ *
+ * COPYRIGHT: Written by John Cunningham Bowler, 2011.
+ * To the extent possible under law, the author has waived all copyright and
+ * related or neighboring rights to this work. This work is published from:
+ * United States.
+ *
+ * Read a PNG and write it out in a fixed format, using the 'simplified API'
+ * that was introduced in libpng-1.6.0.
+ *
+ * This sample code is just the code from the top of 'example.c' with some error
+ * handling added. See example.c for more comments.
+ */
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+/* Normally use <png.h> here to get the installed libpng, but this is done to
+ * ensure the code picks up the local libpng implementation:
+ */
+#include "../../png.h"
+#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && \
+ defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
+
+int main(int argc, const char **argv)
+{
+ int result = 1;
+
+ if (argc == 3)
+ {
+ png_image image;
+
+ /* Only the image structure version number needs to be set. */
+ memset(&image, 0, sizeof image);
+ image.version = PNG_IMAGE_VERSION;
+
+ if (png_image_begin_read_from_file(&image, argv[1]))
+ {
+ png_bytep buffer;
+
+ /* Change this to try different formats! If you set a colormap format
+ * then you must also supply a colormap below.
+ */
+ image.format = PNG_FORMAT_RGBA;
+
+ buffer = malloc(PNG_IMAGE_SIZE(image));
+
+ if (buffer != NULL)
+ {
+ if (png_image_finish_read(&image, NULL/*background*/, buffer,
+ 0/*row_stride*/, NULL/*colormap for PNG_FORMAT_FLAG_COLORMAP */))
+ {
+ if (png_image_write_to_file(&image, argv[2],
+ 0/*convert_to_8bit*/, buffer, 0/*row_stride*/,
+ NULL/*colormap*/))
+ result = 0;
+
+ else
+ fprintf(stderr, "pngtopng: write %s: %s\n", argv[2],
+ image.message);
+
+ free(buffer);
+ }
+
+ else
+ {
+ fprintf(stderr, "pngtopng: read %s: %s\n", argv[1],
+ image.message);
+
+ /* This is the only place where a 'free' is required; libpng does
+ * the cleanup on error and success, but in this case we couldn't
+ * complete the read because of running out of memory.
+ */
+ png_image_free(&image);
+ }
+ }
+
+ else
+ fprintf(stderr, "pngtopng: out of memory: %lu bytes\n",
+ (unsigned long)PNG_IMAGE_SIZE(image));
+ }
+
+ else
+ /* Failed to read the first argument: */
+ fprintf(stderr, "pngtopng: %s: %s\n", argv[1], image.message);
+ }
+
+ else
+ /* Wrong number of arguments */
+ fprintf(stderr, "pngtopng: usage: pngtopng input-file output-file\n");
+
+ return result;
+}
+#endif /* READ && WRITE */
diff --git a/libpng/contrib/examples/simpleover.c b/libpng/contrib/examples/simpleover.c
new file mode 100644
index 0000000..59dd313
--- /dev/null
+++ b/libpng/contrib/examples/simpleover.c
@@ -0,0 +1,648 @@
+/*- simpleover
+ *
+ * COPYRIGHT: Written by John Cunningham Bowler, 2015.
+ * To the extent possible under law, the author has waived all copyright and
+ * related or neighboring rights to this work. This work is published from:
+ * United States.
+ *
+ * Read several PNG files, which should have an alpha channel or transparency
+ * information, and composite them together to produce one or more 16-bit linear
+ * RGBA intermediates. This involves doing the correct 'over' composition to
+ * combine the alpha channels and corresponding data.
+ *
+ * Finally read an output (background) PNG using the 24-bit RGB format (the
+ * PNG will be composited on green (#00ff00) by default if it has an alpha
+ * channel), and apply the intermediate image generated above to specified
+ * locations in the image.
+ *
+ * The command line has the general format:
+ *
+ * simpleover <background.png> [output.png]
+ * {--sprite=width,height,name {[--at=x,y] {sprite.png}}}
+ * {--add=name {x,y}}
+ *
+ * The --sprite and --add options may occur multiple times. They are executed
+ * in order. --add may refer to any sprite already read.
+ *
+ * This code is intended to show how to composite multiple images together
+ * correctly. Apart from the libpng Simplified API the only work done in here
+ * is to combine multiple input PNG images into a single sprite; this involves
+ * a Porter-Duff 'over' operation and the input PNG images may, as a result,
+ * be regarded as being layered one on top of the other with the first (leftmost
+ * on the command line) being at the bottom and the last on the top.
+ */
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <errno.h>
+
+/* Normally use <png.h> here to get the installed libpng, but this is done to
+ * ensure the code picks up the local libpng implementation, so long as this
+ * file is linked against a sufficiently recent libpng (1.6+) it is ok to
+ * change this to <png.h>:
+ */
+#include "../../png.h"
+
+#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
+
+#define sprite_name_chars 15
+struct sprite {
+ FILE *file;
+ png_uint_16p buffer;
+ unsigned int width;
+ unsigned int height;
+ char name[sprite_name_chars+1];
+};
+
+#if 0 /* div by 65535 test program */
+#include <math.h>
+#include <stdio.h>
+
+int main(void) {
+ double err = 0;
+ unsigned int xerr = 0;
+ unsigned int r = 32769;
+ {
+ unsigned int x = 0;
+
+ do {
+ unsigned int t = x + (x >> 16) /*+ (x >> 31)*/ + r;
+ double v = x, errtest;
+
+ if (t < x) {
+ fprintf(stderr, "overflow: %u+%u -> %u\n", x, r, t);
+ return 1;
+ }
+
+ v /= 65535;
+ errtest = v;
+ t >>= 16;
+ errtest -= t;
+
+ if (errtest > err) {
+ err = errtest;
+ xerr = x;
+
+ if (errtest >= .5) {
+ fprintf(stderr, "error: %u/65535 = %f, not %u, error %f\n",
+ x, v, t, errtest);
+ return 0;
+ }
+ }
+ } while (++x <= 65535U*65535U);
+ }
+
+ printf("error %f @ %u\n", err, xerr);
+
+ return 0;
+}
+#endif /* div by 65535 test program */
+
+static void
+sprite_op(const struct sprite *sprite, int x_offset, int y_offset,
+ png_imagep image, const png_uint_16 *buffer)
+{
+ /* This is where the Porter-Duff 'Over' operator is evaluated; change this
+ * code to change the operator (this could be parameterized). Any other
+ * image processing operation could be used here.
+ */
+
+
+ /* Check for an x or y offset that pushes any part of the image beyond the
+ * right or bottom of the sprite:
+ */
+ if ((y_offset < 0 || (unsigned)/*SAFE*/y_offset < sprite->height) &&
+ (x_offset < 0 || (unsigned)/*SAFE*/x_offset < sprite->width))
+ {
+ unsigned int y = 0;
+
+ if (y_offset < 0)
+ y = -y_offset; /* Skip to first visible row */
+
+ do
+ {
+ unsigned int x = 0;
+
+ if (x_offset < 0)
+ x = -x_offset;
+
+ do
+ {
+ /* In and out are RGBA values, so: */
+ const png_uint_16 *in_pixel = buffer + (y * image->width + x)*4;
+ png_uint_32 in_alpha = in_pixel[3];
+
+ /* This is the optimized Porter-Duff 'Over' operation, when the
+ * input alpha is 0 the output is not changed.
+ */
+ if (in_alpha > 0)
+ {
+ png_uint_16 *out_pixel = sprite->buffer +
+ ((y+y_offset) * sprite->width + (x+x_offset))*4;
+
+ /* This is the weight to apply to the output: */
+ in_alpha = 65535-in_alpha;
+
+ if (in_alpha > 0)
+ {
+ /* The input must be composed onto the output. This means
+ * multiplying the current output pixel value by the inverse
+ * of the input alpha (1-alpha). A division is required but
+ * it is by the constant 65535. Approximate this as:
+ *
+ * (x + (x >> 16) + 32769) >> 16;
+ *
+ * This is exact (and does not overflow) for all values of
+ * x in the range 0..65535*65535. (Note that the calculation
+ * produces the closest integer; the maximum error is <0.5).
+ */
+ png_uint_32 tmp;
+
+# define compose(c)\
+ tmp = out_pixel[c] * in_alpha;\
+ tmp = (tmp + (tmp >> 16) + 32769) >> 16;\
+ out_pixel[c] = tmp + in_pixel[c]
+
+ /* The following is very vectorizable... */
+ compose(0);
+ compose(1);
+ compose(2);
+ compose(3);
+ }
+
+ else
+ out_pixel[0] = in_pixel[0],
+ out_pixel[1] = in_pixel[1],
+ out_pixel[2] = in_pixel[2],
+ out_pixel[3] = in_pixel[3];
+ }
+ }
+ while (++x < image->width);
+ }
+ while (++y < image->height);
+ }
+}
+
+static int
+create_sprite(struct sprite *sprite, int *argc, const char ***argv)
+{
+ /* Read the arguments and create this sprite. The sprite buffer has already
+ * been allocated. This reads the input PNGs one by one in linear format,
+ * composes them onto the sprite buffer (the code in the function above)
+ * then saves the result, converting it on the fly to PNG RGBA 8-bit format.
+ */
+ while (*argc > 0)
+ {
+ char tombstone;
+ int x = 0, y = 0;
+
+ if ((*argv)[0][0] == '-' && (*argv)[0][1] == '-')
+ {
+ /* The only supported option is --at. */
+ if (sscanf((*argv)[0], "--at=%d,%d%c", &x, &y, &tombstone) != 2)
+ break; /* success; caller will parse this option */
+
+ ++*argv, --*argc;
+ }
+
+ else
+ {
+ /* The argument has to be a file name */
+ png_image image;
+
+ image.version = PNG_IMAGE_VERSION;
+ image.opaque = NULL;
+
+ if (png_image_begin_read_from_file(&image, (*argv)[0]))
+ {
+ png_uint_16p buffer;
+
+ image.format = PNG_FORMAT_LINEAR_RGB_ALPHA;
+
+ buffer = malloc(PNG_IMAGE_SIZE(image));
+
+ if (buffer != NULL)
+ {
+ if (png_image_finish_read(&image, NULL/*background*/, buffer,
+ 0/*row_stride*/,
+ NULL/*colormap for PNG_FORMAT_FLAG_COLORMAP*/))
+ {
+ /* This is the place where the Porter-Duff 'Over' operator
+ * needs to be done by this code. In fact, any image
+ * processing required can be done here; the data is in
+ * the correct format (linear, 16-bit) and source and
+ * destination are in memory.
+ */
+ sprite_op(sprite, x, y, &image, buffer);
+ free(buffer);
+ ++*argv, --*argc;
+ /* And continue to the next argument */
+ continue;
+ }
+
+ else
+ {
+ free(buffer);
+ fprintf(stderr, "simpleover: read %s: %s\n", (*argv)[0],
+ image.message);
+ }
+ }
+
+ else
+ {
+ fprintf(stderr, "simpleover: out of memory: %lu bytes\n",
+ (unsigned long)PNG_IMAGE_SIZE(image));
+
+ /* png_image_free must be called if we abort the Simplified API
+ * read because of a problem detected in this code. If problems
+ * are detected in the Simplified API it cleans up itself.
+ */
+ png_image_free(&image);
+ }
+ }
+
+ else
+ {
+ /* Failed to read the first argument: */
+ fprintf(stderr, "simpleover: %s: %s\n", (*argv)[0], image.message);
+ }
+
+ return 0; /* failure */
+ }
+ }
+
+ /* All the sprite operations have completed successfully. Save the RGBA
+ * buffer as a PNG using the simplified write API.
+ */
+ sprite->file = tmpfile();
+
+ if (sprite->file != NULL)
+ {
+ png_image save;
+
+ memset(&save, 0, sizeof save);
+ save.version = PNG_IMAGE_VERSION;
+ save.opaque = NULL;
+ save.width = sprite->width;
+ save.height = sprite->height;
+ save.format = PNG_FORMAT_LINEAR_RGB_ALPHA;
+ save.flags = PNG_IMAGE_FLAG_FAST;
+ save.colormap_entries = 0;
+
+ if (png_image_write_to_stdio(&save, sprite->file, 1/*convert_to_8_bit*/,
+ sprite->buffer, 0/*row_stride*/, NULL/*colormap*/))
+ {
+ /* Success; the buffer is no longer needed: */
+ free(sprite->buffer);
+ sprite->buffer = NULL;
+ return 1; /* ok */
+ }
+
+ else
+ fprintf(stderr, "simpleover: write sprite %s: %s\n", sprite->name,
+ save.message);
+ }
+
+ else
+ fprintf(stderr, "simpleover: sprite %s: could not allocate tmpfile: %s\n",
+ sprite->name, strerror(errno));
+
+ return 0; /* fail */
+}
+
+static int
+add_sprite(png_imagep output, png_bytep out_buf, struct sprite *sprite,
+ int *argc, const char ***argv)
+{
+ /* Given a --add argument naming this sprite, perform the operations listed
+ * in the following arguments. The arguments are expected to have the form
+ * (x,y), which is just an offset at which to add the sprite to the
+ * output.
+ */
+ while (*argc > 0)
+ {
+ char tombstone;
+ int x, y;
+
+ if ((*argv)[0][0] == '-' && (*argv)[0][1] == '-')
+ return 1; /* success */
+
+ if (sscanf((*argv)[0], "%d,%d%c", &x, &y, &tombstone) == 2)
+ {
+ /* Now add the new image into the sprite data, but only if it
+ * will fit.
+ */
+ if (x < 0 || y < 0 ||
+ (unsigned)/*SAFE*/x >= output->width ||
+ (unsigned)/*SAFE*/y >= output->height ||
+ sprite->width > output->width-x ||
+ sprite->height > output->height-y)
+ {
+ fprintf(stderr, "simpleover: sprite %s @ (%d,%d) outside image\n",
+ sprite->name, x, y);
+ /* Could just skip this, but for the moment it is an error */
+ return 0; /* error */
+ }
+
+ else
+ {
+ /* Since we know the sprite fits we can just read it into the
+ * output using the simplified API.
+ */
+ png_image in;
+
+ in.version = PNG_IMAGE_VERSION;
+ rewind(sprite->file);
+
+ if (png_image_begin_read_from_stdio(&in, sprite->file))
+ {
+ in.format = PNG_FORMAT_RGB; /* force compose */
+
+ if (png_image_finish_read(&in, NULL/*background*/,
+ out_buf + (y*output->width + x)*3/*RGB*/,
+ output->width*3/*row_stride*/,
+ NULL/*colormap for PNG_FORMAT_FLAG_COLORMAP*/))
+ {
+ ++*argv, --*argc;
+ continue;
+ }
+ }
+
+ /* The read failed: */
+ fprintf(stderr, "simpleover: add sprite %s: %s\n", sprite->name,
+ in.message);
+ return 0; /* error */
+ }
+ }
+
+ else
+ {
+ fprintf(stderr, "simpleover: --add='%s': invalid position %s\n",
+ sprite->name, (*argv)[0]);
+ return 0; /* error */
+ }
+ }
+
+ return 1; /* ok */
+}
+
+static int
+simpleover_process(png_imagep output, png_bytep out_buf, int argc,
+ const char **argv)
+{
+ int result = 1; /* success */
+# define csprites 10/*limit*/
+# define str(a) #a
+ int nsprites = 0;
+ struct sprite sprites[csprites];
+
+ while (argc > 0)
+ {
+ result = 0; /* fail */
+
+ if (strncmp(argv[0], "--sprite=", 9) == 0)
+ {
+ char tombstone;
+
+ if (nsprites < csprites)
+ {
+ int n;
+
+ sprites[nsprites].width = sprites[nsprites].height = 0;
+ sprites[nsprites].name[0] = 0;
+
+ n = sscanf(argv[0], "--sprite=%u,%u,%" str(sprite_name_chars) "s%c",
+ &sprites[nsprites].width, &sprites[nsprites].height,
+ sprites[nsprites].name, &tombstone);
+
+ if ((n == 2 || n == 3) &&
+ sprites[nsprites].width > 0 && sprites[nsprites].height > 0)
+ {
+ size_t buf_size, tmp;
+
+ /* Default a name if not given. */
+ if (sprites[nsprites].name[0] == 0)
+ sprintf(sprites[nsprites].name, "sprite-%d", nsprites+1);
+
+ /* Allocate a buffer for the sprite and calculate the buffer
+ * size:
+ */
+ buf_size = sizeof (png_uint_16 [4]);
+ buf_size *= sprites[nsprites].width;
+ buf_size *= sprites[nsprites].height;
+
+ /* This can overflow a (size_t); check for this: */
+ tmp = buf_size;
+ tmp /= sprites[nsprites].width;
+ tmp /= sprites[nsprites].height;
+
+ if (tmp == sizeof (png_uint_16 [4]))
+ {
+ sprites[nsprites].buffer = malloc(buf_size);
+ /* This buffer must be initialized to transparent: */
+ memset(sprites[nsprites].buffer, 0, buf_size);
+
+ if (sprites[nsprites].buffer != NULL)
+ {
+ sprites[nsprites].file = NULL;
+ ++argv, --argc;
+
+ if (create_sprite(sprites+nsprites++, &argc, &argv))
+ {
+ result = 1; /* still ok */
+ continue;
+ }
+
+ break; /* error */
+ }
+ }
+
+ /* Overflow, or OOM */
+ fprintf(stderr, "simpleover: %s: sprite too large\n", argv[0]);
+ break;
+ }
+
+ else
+ {
+ fprintf(stderr, "simpleover: %s: invalid sprite (%u,%u)\n",
+ argv[0], sprites[nsprites].width, sprites[nsprites].height);
+ break;
+ }
+ }
+
+ else
+ {
+ fprintf(stderr, "simpleover: %s: too many sprites\n", argv[0]);
+ break;
+ }
+ }
+
+ else if (strncmp(argv[0], "--add=", 6) == 0)
+ {
+ const char *name = argv[0]+6;
+ int isprite = nsprites;
+
+ ++argv, --argc;
+
+ while (--isprite >= 0)
+ {
+ if (strcmp(sprites[isprite].name, name) == 0)
+ {
+ if (!add_sprite(output, out_buf, sprites+isprite, &argc, &argv))
+ goto out; /* error in add_sprite */
+
+ break;
+ }
+ }
+
+ if (isprite < 0) /* sprite not found */
+ {
+ fprintf(stderr, "simpleover: --add='%s': sprite not found\n", name);
+ break;
+ }
+ }
+
+ else
+ {
+ fprintf(stderr, "simpleover: %s: unrecognized operation\n", argv[0]);
+ break;
+ }
+
+ result = 1; /* ok */
+ }
+
+ /* Clean up the cache of sprites: */
+out:
+ while (--nsprites >= 0)
+ {
+ if (sprites[nsprites].buffer != NULL)
+ free(sprites[nsprites].buffer);
+
+ if (sprites[nsprites].file != NULL)
+ (void)fclose(sprites[nsprites].file);
+ }
+
+ return result;
+}
+
+int main(int argc, const char **argv)
+{
+ int result = 1; /* default to fail */
+
+ if (argc >= 2)
+ {
+ int argi = 2;
+ const char *output = NULL;
+ png_image image;
+
+ if (argc > 2 && argv[2][0] != '-'/*an operation*/)
+ {
+ output = argv[2];
+ argi = 3;
+ }
+
+ image.version = PNG_IMAGE_VERSION;
+ image.opaque = NULL;
+
+ if (png_image_begin_read_from_file(&image, argv[1]))
+ {
+ png_bytep buffer;
+
+ image.format = PNG_FORMAT_RGB; /* 24-bit RGB */
+
+ buffer = malloc(PNG_IMAGE_SIZE(image));
+
+ if (buffer != NULL)
+ {
+ png_color background = {0, 0xff, 0}; /* fully saturated green */
+
+ if (png_image_finish_read(&image, &background, buffer,
+ 0/*row_stride*/, NULL/*colormap for PNG_FORMAT_FLAG_COLORMAP */))
+ {
+ /* At this point png_image_finish_read has cleaned up the
+ * allocated data in png_image, and only the buffer needs to be
+ * freed.
+ *
+ * Perform the remaining operations:
+ */
+ if (simpleover_process(&image, buffer, argc-argi, argv+argi))
+ {
+ /* Write the output: */
+ if ((output != NULL &&
+ png_image_write_to_file(&image, output,
+ 0/*convert_to_8bit*/, buffer, 0/*row_stride*/,
+ NULL/*colormap*/)) ||
+ (output == NULL &&
+ png_image_write_to_stdio(&image, stdout,
+ 0/*convert_to_8bit*/, buffer, 0/*row_stride*/,
+ NULL/*colormap*/)))
+ result = 0;
+
+ else
+ fprintf(stderr, "simpleover: write %s: %s\n",
+ output == NULL ? "stdout" : output, image.message);
+ }
+
+ /* else simpleover_process writes an error message */
+ }
+
+ else
+ fprintf(stderr, "simpleover: read %s: %s\n", argv[1],
+ image.message);
+
+ free(buffer);
+ }
+
+ else
+ {
+ fprintf(stderr, "simpleover: out of memory: %lu bytes\n",
+ (unsigned long)PNG_IMAGE_SIZE(image));
+
+ /* This is the only place where a 'free' is required; libpng does
+ * the cleanup on error and success, but in this case we couldn't
+ * complete the read because of running out of memory.
+ */
+ png_image_free(&image);
+ }
+ }
+
+ else
+ {
+ /* Failed to read the first argument: */
+ fprintf(stderr, "simpleover: %s: %s\n", argv[1], image.message);
+ }
+ }
+
+ else
+ {
+ /* Usage message */
+ fprintf(stderr,
+ "simpleover: usage: simpleover background.png [output.png]\n"
+ " Output 'background.png' as a 24-bit RGB PNG file in 'output.png'\n"
+ " or, if not given, stdout. 'background.png' will be composited\n"
+ " on fully saturated green.\n"
+ "\n"
+ " Optionally, before output, process additional PNG files:\n"
+ "\n"
+ " --sprite=width,height,name {[--at=x,y] {sprite.png}}\n"
+ " Produce a transparent sprite of size (width,height) and with\n"
+ " name 'name'.\n"
+ " For each sprite.png composite it using a Porter-Duff 'Over'\n"
+ " operation at offset (x,y) in the sprite (defaulting to (0,0)).\n"
+ " Input PNGs will be truncated to the area of the sprite.\n"
+ "\n"
+ " --add='name' {x,y}\n"
+ " Optionally, before output, composite a sprite, 'name', which\n"
+ " must have been previously produced using --sprite, at each\n"
+ " offset (x,y) in the output image. Each sprite must fit\n"
+ " completely within the output image.\n"
+ "\n"
+ " PNG files are processed in the order they occur on the command\n"
+ " line and thus the first PNG processed appears as the bottommost\n"
+ " in the output image.\n");
+ }
+
+ return result;
+}
+#endif /* SIMPLIFIED_READ */
diff --git a/libpng/contrib/gregbook/COPYING b/libpng/contrib/gregbook/COPYING
new file mode 100644
index 0000000..a3e9774
--- /dev/null
+++ b/libpng/contrib/gregbook/COPYING
@@ -0,0 +1,340 @@
+ GNU GENERAL PUBLIC LICENSE
+ Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.
+ 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+ Preamble
+
+ The licenses for most software are designed to take away your
+freedom to share and change it. By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users. This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it. (Some other Free Software Foundation software is covered by
+the GNU Library General Public License instead.) You can apply it to
+your programs, too.
+
+ When we speak of free software, we are referring to freedom, not
+price. Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
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+anyone to deny you these rights or to ask you to surrender the rights.
+These restrictions translate to certain responsibilities for you if you
+distribute copies of the software, or if you modify it.
+
+ For example, if you distribute copies of such a program, whether
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+you have. You must make sure that they, too, receive or can get the
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+distribute and/or modify the software.
+
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+that everyone understands that there is no warranty for this free
+software. If the software is modified by someone else and passed on, we
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+ Finally, any free program is threatened constantly by software
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+ GNU GENERAL PUBLIC LICENSE
+ TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+ 0. This License applies to any program or other work which contains
+a notice placed by the copyright holder saying it may be distributed
+under the terms of this General Public License. The "Program", below,
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+Activities other than copying, distribution and modification are not
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+running the Program is not restricted, and the output from the Program
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+Whether that is true depends on what the Program does.
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+ 1. You may copy and distribute verbatim copies of the Program's
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+You may charge a fee for the physical act of transferring a copy, and
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+with the Program (or with a work based on the Program) on a volume of
+a storage or distribution medium does not bring the other work under
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+ 5. You are not required to accept this License, since you have not
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+ 6. Each time you redistribute the Program (or any work based on the
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+infringement or for any other reason (not limited to patent issues),
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+If any portion of this section is held invalid or unenforceable under
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+
+This section is intended to make thoroughly clear what is believed to
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+
+ 8. If the distribution and/or use of the Program is restricted in
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+original copyright holder who places the Program under this License
+may add an explicit geographical distribution limitation excluding
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+ 9. The Free Software Foundation may publish revised and/or new versions
+of the General Public License from time to time. Such new versions will
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+
+Each version is given a distinguishing version number. If the Program
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+either of that version or of any later version published by the Free
+Software Foundation. If the Program does not specify a version number of
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+Foundation.
+
+ 10. If you wish to incorporate parts of the Program into other free
+programs whose distribution conditions are different, write to the author
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+ NO WARRANTY
+
+ 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
+OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
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+TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE
+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
+REPAIR OR CORRECTION.
+
+ 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
+REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
+OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
+TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGES.
+
+ END OF TERMS AND CONDITIONS
+
+ How to Apply These Terms to Your New Programs
+
+ If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+ To do so, attach the following notices to the program. It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+ <one line to give the program's name and a brief idea of what it does.>
+ Copyright (C) <year> <name of author>
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+ Gnomovision version 69, Copyright (C) year name of author
+ Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+ This is free software, and you are welcome to redistribute it
+ under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License. Of course, the commands you use may
+be called something other than `show w' and `show c'; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the program, if
+necessary. Here is a sample; alter the names:
+
+ Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+ `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+ <signature of Ty Coon>, 1 April 1989
+ Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs. If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library. If this is what you want to do, use the GNU Library General
+Public License instead of this License.
diff --git a/libpng/contrib/gregbook/LICENSE b/libpng/contrib/gregbook/LICENSE
new file mode 100644
index 0000000..d956717
--- /dev/null
+++ b/libpng/contrib/gregbook/LICENSE
@@ -0,0 +1,50 @@
+ ---------------------------------------------------------------------------
+
+ Copyright (c) 1998-2008 Greg Roelofs. All rights reserved.
+
+ This software is provided "as is," without warranty of any kind,
+ express or implied. In no event shall the author or contributors
+ be held liable for any damages arising in any way from the use of
+ this software.
+
+ The contents of this file are DUAL-LICENSED. You may modify and/or
+ redistribute this software according to the terms of one of the
+ following two licenses (at your option):
+
+
+ LICENSE 1 ("BSD-like with advertising clause"):
+
+ Permission is granted to anyone to use this software for any purpose,
+ including commercial applications, and to alter it and redistribute
+ it freely, subject to the following restrictions:
+
+ 1. Redistributions of source code must retain the above copyright
+ notice, disclaimer, and this list of conditions.
+ 2. Redistributions in binary form must reproduce the above copyright
+ notice, disclaimer, and this list of conditions in the documenta-
+ tion and/or other materials provided with the distribution.
+ 3. All advertising materials mentioning features or use of this
+ software must display the following acknowledgment:
+
+ This product includes software developed by Greg Roelofs
+ and contributors for the book, "PNG: The Definitive Guide,"
+ published by O'Reilly and Associates.
+
+
+ LICENSE 2 (GNU GPL v2 or later):
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ ---------------------------------------------------------------------------
diff --git a/libpng/contrib/gregbook/Makefile.mingw32 b/libpng/contrib/gregbook/Makefile.mingw32
new file mode 100644
index 0000000..3a3ff60
--- /dev/null
+++ b/libpng/contrib/gregbook/Makefile.mingw32
@@ -0,0 +1,131 @@
+# Sample makefile for rpng-win / rpng2-win / wpng using mingw32-gcc and make.
+# Greg Roelofs
+# Last modified: 2 June 2007
+#
+# The programs built by this makefile are described in the book,
+# "PNG: The Definitive Guide," by Greg Roelofs (O'Reilly and
+# Associates, 1999). Go buy a copy, eh? Well, OK, it's not
+# generally for sale anymore, but it's the thought that counts,
+# right? (Hint: http://www.libpng.org/pub/png/book/ )
+#
+# Invoke this makefile from a DOS-prompt window via:
+#
+# make -f Makefile.mingw32
+#
+# This makefile assumes libpng and zlib have already been built or downloaded
+# and are in subdirectories at the same level as the current subdirectory
+# (as indicated by the PNGDIR and ZDIR macros below). It makes no assumptions
+# at all about the mingw32 installation tree (W32DIR). Edit as appropriate.
+#
+# Note that the names of the dynamic and static libpng and zlib libraries
+# used below may change in later releases of the libraries. This makefile
+# builds both statically and dynamically linked executables by default.
+# (You need only one set, but for testing it can be handy to have both.)
+
+
+# macros --------------------------------------------------------------------
+
+#PNGDIR = ../..# for libpng-x.y.z/contrib/gregbook builds
+PNGDIR = ../libpng-win32
+PNGINC = -I$(PNGDIR)
+PNGLIBd = $(PNGDIR)/libpng.dll.a # dynamically linked
+PNGLIBs = $(PNGDIR)/libpng.a # statically linked, local libpng
+
+#ZDIR = ../../../zlib-win32# for libpng-x.y.z/contrib/gregbook builds
+ZDIR = ../zlib-win32
+ZINC = -I$(ZDIR)
+ZLIBd = $(ZDIR)/libzdll.a
+ZLIBs = $(ZDIR)/libz.a
+
+# change this to be the path where mingw32 installs its stuff:
+W32DIR =
+#W32DIR = /usr/local/cross-tools/i386-mingw32msvc
+W32INC = -I$(W32DIR)/include
+W32LIB = $(W32DIR)/lib/libuser32.a $(W32DIR)/lib/libgdi32.a
+
+CC = gcc
+#CC = i386-mingw32msvc-gcc # e.g., Linux -> Win32 cross-compilation
+LD = $(CC)
+RM = rm -f
+CPPFLAGS = $(INCS)
+CFLAGS = -O -Wall $(MINGW_CCFLAGS)
+# [note that -Wall is a gcc-specific compilation flag ("most warnings on")]
+# [-ansi, -pedantic and -W can also be used]
+LDFLAGS = $(MINGW_LDFLAGS)
+O = .o
+E = .exe
+
+INCS = $(PNGINC) $(ZINC) $(W32INC)
+RLIBSd = $(PNGLIBd) $(ZLIBd) $(W32LIB) -lm
+RLIBSs = $(PNGLIBs) $(ZLIBs) $(W32LIB) -lm
+WLIBSd = $(PNGLIBd) $(ZLIBd)
+WLIBSs = $(PNGLIBs) $(ZLIBs)
+
+RPNG = rpng-win
+RPNG2 = rpng2-win
+WPNG = wpng
+
+ROBJSd = $(RPNG)$(O) readpng.pic$(O)
+ROBJS2d = $(RPNG2)$(O) readpng2.pic$(O)
+WOBJSd = $(WPNG)$(O) writepng.pic$(O)
+
+RPNGs = $(RPNG)-static
+RPNG2s = $(RPNG2)-static
+WPNGs = $(WPNG)-static
+
+ROBJSs = $(RPNG)$(O) readpng$(O)
+ROBJS2s = $(RPNG2)$(O) readpng2$(O)
+WOBJSs = $(WPNG)$(O) writepng$(O)
+
+STATIC_EXES = $(RPNGs)$(E) $(RPNG2s)$(E) $(WPNGs)$(E)
+DYNAMIC_EXES = $(RPNG)$(E) $(RPNG2)$(E) $(WPNG)$(E)
+
+EXES = $(STATIC_EXES) $(DYNAMIC_EXES)
+
+
+# implicit make rules -------------------------------------------------------
+
+.c$(O):
+ $(CC) -c $(CPPFLAGS) $(CFLAGS) $<
+
+%.pic$(O): %.c
+ $(CC) -c $(CPPFLAGS) $(CFLAGS) -DPNG_BUILD_DLL -o $@ $<
+
+
+# dependencies --------------------------------------------------------------
+
+all: $(EXES)
+
+$(RPNGs)$(E): $(ROBJSs)
+ $(LD) $(LDFLAGS) -o $@ $(ROBJSs) $(RLIBSs)
+
+$(RPNG)$(E): $(ROBJSd)
+ $(LD) $(LDFLAGS) -o $@ $(ROBJSd) $(RLIBSd)
+
+$(RPNG2s)$(E): $(ROBJS2s)
+ $(LD) $(LDFLAGS) -o $@ $(ROBJS2s) $(RLIBSs)
+
+$(RPNG2)$(E): $(ROBJS2d)
+ $(LD) $(LDFLAGS) -o $@ $(ROBJS2d) $(RLIBSd)
+
+$(WPNGs)$(E): $(WOBJSs)
+ $(LD) $(LDFLAGS) -o $@ $(WOBJSs) $(WLIBSs)
+
+$(WPNG)$(E): $(WOBJSd)
+ $(LD) $(LDFLAGS) -o $@ $(WOBJSd) $(WLIBSd)
+
+$(RPNG)$(O): $(RPNG).c readpng.h
+$(RPNG2)$(O): $(RPNG2).c readpng2.h
+$(WPNG)$(O): $(WPNG).c writepng.h
+
+readpng$(O) readpng.pic$(O): readpng.c readpng.h
+readpng2$(O) readpng2.pic$(O): readpng2.c readpng2.h
+writepng$(O) writepng.pic$(O): writepng.c writepng.h
+
+
+# maintenance ---------------------------------------------------------------
+
+clean:
+ $(RM) $(EXES)
+ $(RM) $(ROBJSs) $(ROBJS2s) $(WOBJSs)
+ $(RM) $(ROBJSd) $(ROBJS2d) $(WOBJSd)
diff --git a/libpng/contrib/gregbook/Makefile.sgi b/libpng/contrib/gregbook/Makefile.sgi
new file mode 100644
index 0000000..94d61b4
--- /dev/null
+++ b/libpng/contrib/gregbook/Makefile.sgi
@@ -0,0 +1,105 @@
+# Sample makefile for rpng-x / rpng2-x / wpng for SGI using cc and make.
+# Greg Roelofs
+# Last modified: 7 March 2002
+#
+# The programs built by this makefile are described in the book,
+# "PNG: The Definitive Guide," by Greg Roelofs (O'Reilly and
+# Associates, 1999). Go buy a copy, eh? Buy some for friends
+# and family, too. (Not that this is a blatant plug or anything.)
+#
+# Invoke this makefile from a shell prompt in the usual way; for example:
+#
+# make -f Makefile.sgi
+#
+# This makefile assumes libpng and zlib have already been built or downloaded
+# and are both installed in /usr/local/{include,lib} (as indicated by the
+# PNG* and Z* macros below). Edit as appropriate--choose only ONE each of
+# the PNGINC, PNGLIB, ZINC and ZLIB lines.
+#
+# This makefile builds dynamically linked executables (against libpng and zlib,
+# that is), but that can be changed by uncommenting the appropriate PNGLIB and
+# ZLIB lines.
+
+
+# macros --------------------------------------------------------------------
+
+PNGINC = -I/usr/local/include/libpng16
+PNGLIB = -L/usr/local/lib -lpng16 # dynamically linked against libpng
+#PNGLIB = /usr/local/lib/libpng16.a # statically linked against libpng
+# or:
+#PNGINC = -I../..
+#PNGLIB = -L../.. -lpng
+#PNGLIB = ../../libpng.a
+
+ZINC = -I/usr/local/include
+ZLIB = -L/usr/local/lib -lz # dynamically linked against zlib
+#ZLIB = /usr/local/lib/libz.a # statically linked against zlib
+#ZINC = -I../zlib
+#ZLIB = -L../zlib -lz
+#ZLIB = ../../../zlib/libz.a
+
+XINC = -I/usr/include/X11 # old-style, stock X distributions
+XLIB = -L/usr/lib/X11 -lX11
+#XINC = -I/usr/openwin/include # Sun workstations (OpenWindows)
+#XLIB = -L/usr/openwin/lib -lX11
+#XINC = -I/usr/X11R6/include # new X distributions (XFree86, etc.)
+#XLIB = -L/usr/X11R6/lib -lX11
+
+INCS = $(PNGINC) $(ZINC) $(XINC)
+RLIBS = $(PNGLIB) $(ZLIB) $(XLIB) -lm
+WLIBS = $(PNGLIB) $(ZLIB)
+
+CC = cc
+LD = cc
+RM = rm -f
+# ABI must be the same as that used to build libpng.
+ABI =
+CPPFLAGS =
+CFLAGS = $(ABI) -O -fullwarn $(INCS)
+LDFLAGS = $(ABI)
+O = .o
+E =
+
+RPNG = rpng-x
+RPNG2 = rpng2-x
+WPNG = wpng
+
+ROBJS = $(RPNG)$(O) readpng$(O)
+ROBJS2 = $(RPNG2)$(O) readpng2$(O)
+WOBJS = $(WPNG)$(O) writepng$(O)
+
+EXES = $(RPNG)$(E) $(RPNG2)$(E) $(WPNG)$(E)
+
+
+# implicit make rules -------------------------------------------------------
+
+.c$(O):
+ $(CC) -c $(CPPFLAGS) $(CFLAGS) $<
+
+
+# dependencies --------------------------------------------------------------
+
+all: $(EXES)
+
+$(RPNG)$(E): $(ROBJS)
+ $(LD) $(LDFLAGS) -o $@ $(ROBJS) $(RLIBS)
+
+$(RPNG2)$(E): $(ROBJS2)
+ $(LD) $(LDFLAGS) -o $@ $(ROBJS2) $(RLIBS)
+
+$(WPNG)$(E): $(WOBJS)
+ $(LD) $(LDFLAGS) -o $@ $(WOBJS) $(WLIBS)
+
+$(RPNG)$(O): $(RPNG).c readpng.h
+$(RPNG2)$(O): $(RPNG2).c readpng2.h
+$(WPNG)$(O): $(WPNG).c writepng.h
+
+readpng$(O): readpng.c readpng.h
+readpng2$(O): readpng2.c readpng2.h
+writepng$(O): writepng.c writepng.h
+
+
+# maintenance ---------------------------------------------------------------
+
+clean:
+ $(RM) $(EXES) $(ROBJS) $(ROBJS2) $(WOBJS)
diff --git a/libpng/contrib/gregbook/Makefile.unx b/libpng/contrib/gregbook/Makefile.unx
new file mode 100644
index 0000000..1a73e03
--- /dev/null
+++ b/libpng/contrib/gregbook/Makefile.unx
@@ -0,0 +1,134 @@
+# Sample makefile for rpng-x / rpng2-x / wpng using gcc and make.
+# Greg Roelofs
+# Last modified: 2 June 2007
+#
+# The programs built by this makefile are described in the book,
+# "PNG: The Definitive Guide," by Greg Roelofs (O'Reilly and
+# Associates, 1999). Go buy a copy, eh? Well, OK, it's not
+# generally for sale anymore, but it's the thought that counts,
+# right? (Hint: http://www.libpng.org/pub/png/book/ )
+#
+# Invoke this makefile from a shell prompt in the usual way; for example:
+#
+# make -f Makefile.unx
+#
+# This makefile assumes libpng and zlib have already been built or downloaded
+# and are installed in /usr/local/{include,lib} or as otherwise indicated by
+# the PNG* and Z* macros below. Edit as appropriate--choose only ONE each of
+# the PNGINC, PNGLIBd, PNGLIBs, ZINC, ZLIBd and ZLIBs lines.
+#
+# This makefile builds both dynamically and statically linked executables
+# (against libpng and zlib, that is), but that can be changed by modifying
+# the "EXES =" line. (You need only one set, but for testing it can be handy
+# to have both.)
+
+
+# macros --------------------------------------------------------------------
+
+#PNGDIR = /usr/local/lib
+#PNGINC = -I/usr/local/include/libpng16
+#PNGLIBd = -L$(PNGDIR) -lpng16 # dynamically linked, installed libpng
+#PNGLIBs = $(PNGDIR)/libpng16.a # statically linked, installed libpng
+# or:
+PNGDIR = ../..# this one is for libpng-x.y.z/contrib/gregbook builds
+#PNGDIR = ../libpng
+PNGINC = -I$(PNGDIR)
+PNGLIBd = -Wl,-rpath,$(PNGDIR) -L$(PNGDIR) -lpng16 # dynamically linked
+PNGLIBs = $(PNGDIR)/libpng.a # statically linked, local libpng
+
+ZDIR = /usr/local/lib
+#ZDIR = /usr/lib64
+ZINC = -I/usr/local/include
+ZLIBd = -L$(ZDIR) -lz # dynamically linked against zlib
+ZLIBs = $(ZDIR)/libz.a # statically linked against zlib
+# or:
+#ZDIR = ../zlib
+#ZINC = -I$(ZDIR)
+#ZLIBd = -Wl,-rpath,$(ZDIR) -L$(ZDIR) -lz # -rpath allows in-place testing
+#ZLIBs = $(ZDIR)/libz.a
+
+#XINC = -I/usr/include # old-style, stock X distributions
+#XLIB = -L/usr/lib/X11 -lX11 # (including SGI IRIX)
+#XINC = -I/usr/openwin/include # Sun workstations (OpenWindows)
+#XLIB = -L/usr/openwin/lib -lX11
+XINC = -I/usr/X11R6/include # new X distributions (X.org, etc.)
+XLIB = -L/usr/X11R6/lib -lX11
+#XLIB = -L/usr/X11R6/lib64 -lX11 # e.g., Red Hat on AMD64
+
+INCS = $(PNGINC) $(ZINC) $(XINC)
+RLIBSd = $(PNGLIBd) $(ZLIBd) $(XLIB) -lm
+RLIBSs = $(PNGLIBs) $(ZLIBs) $(XLIB) -lm
+WLIBSd = $(PNGLIBd) $(ZLIBd) -lm
+WLIBSs = $(PNGLIBs) $(ZLIBs) -lm
+
+CC = gcc
+LD = gcc
+RM = rm -f
+CPPFLAGS = $(INCS) -DFEATURE_LOOP
+CFLAGS = -O -Wall
+#CFLAGS = -O -W -Wall -Wextra -pedantic -ansi
+# [note that -Wall is a gcc-specific compilation flag ("most warnings on")]
+# [-ansi, -pedantic, -Wextra, and -W can also be used]
+LDFLAGS =
+O = .o
+E =
+
+RPNG = rpng-x
+RPNG2 = rpng2-x
+WPNG = wpng
+
+RPNGs = $(RPNG)-static
+RPNG2s = $(RPNG2)-static
+WPNGs = $(WPNG)-static
+
+ROBJS = $(RPNG)$(O) readpng$(O)
+ROBJS2 = $(RPNG2)$(O) readpng2$(O)
+WOBJS = $(WPNG)$(O) writepng$(O)
+
+STATIC_EXES = $(RPNGs)$(E) $(RPNG2s)$(E) $(WPNGs)$(E)
+DYNAMIC_EXES = $(RPNG)$(E) $(RPNG2)$(E) $(WPNG)$(E)
+
+EXES = $(STATIC_EXES) $(DYNAMIC_EXES)
+
+
+# implicit make rules -------------------------------------------------------
+
+.c$(O):
+ $(CC) -c $(CPPFLAGS) $(CFLAGS) $<
+
+
+# dependencies --------------------------------------------------------------
+
+all: $(EXES)
+
+$(RPNGs)$(E): $(ROBJS)
+ $(LD) $(LDFLAGS) -o $@ $(ROBJS) $(RLIBSs)
+
+$(RPNG)$(E): $(ROBJS)
+ $(LD) $(LDFLAGS) -o $@ $(ROBJS) $(RLIBSd)
+
+$(RPNG2s)$(E): $(ROBJS2)
+ $(LD) $(LDFLAGS) -o $@ $(ROBJS2) $(RLIBSs)
+
+$(RPNG2)$(E): $(ROBJS2)
+ $(LD) $(LDFLAGS) -o $@ $(ROBJS2) $(RLIBSd)
+
+$(WPNGs)$(E): $(WOBJS)
+ $(LD) $(LDFLAGS) -o $@ $(WOBJS) $(WLIBSs)
+
+$(WPNG)$(E): $(WOBJS)
+ $(LD) $(LDFLAGS) -o $@ $(WOBJS) $(WLIBSd)
+
+$(RPNG)$(O): $(RPNG).c readpng.h
+$(RPNG2)$(O): $(RPNG2).c readpng2.h
+$(WPNG)$(O): $(WPNG).c writepng.h
+
+readpng$(O): readpng.c readpng.h
+readpng2$(O): readpng2.c readpng2.h
+writepng$(O): writepng.c writepng.h
+
+
+# maintenance ---------------------------------------------------------------
+
+clean:
+ $(RM) $(EXES) $(ROBJS) $(ROBJS2) $(WOBJS)
diff --git a/libpng/contrib/gregbook/Makefile.w32 b/libpng/contrib/gregbook/Makefile.w32
new file mode 100644
index 0000000..ab7dcf7
--- /dev/null
+++ b/libpng/contrib/gregbook/Makefile.w32
@@ -0,0 +1,114 @@
+# Sample makefile for rpng-win / rpng2-win / wpng using MSVC and NMAKE.
+# Greg Roelofs
+# Last modified: 2 June 2007
+#
+# The programs built by this makefile are described in the book,
+# "PNG: The Definitive Guide," by Greg Roelofs (O'Reilly and
+# Associates, 1999). Go buy a copy, eh? Well, OK, it's not
+# generally for sale anymore, but it's the thought that counts,
+# right? (Hint: http://www.libpng.org/pub/png/book/ )
+#
+# Invoke this makefile from a DOS prompt window via:
+#
+# %devstudio%\vc\bin\vcvars32.bat
+# nmake -nologo -f Makefile.w32
+#
+# where %devstudio% is the installation directory for MSVC / DevStudio. If
+# you get "environment out of space" errors, create a desktop shortcut with
+# "c:\windows\command.com /e:4096" as the program command line and set the
+# working directory to this directory. Then double-click to open the new
+# DOS-prompt window with a bigger environment and retry the commands above.
+#
+# This makefile assumes libpng and zlib have already been built or downloaded
+# and are in subdirectories at the same level as the current subdirectory
+# (as indicated by the PNGPATH and ZPATH macros below). Edit as appropriate.
+#
+# Note that the names of the dynamic and static libpng and zlib libraries
+# used below may change in later releases of the libraries. This makefile
+# builds statically linked executables, but that can be changed by uncom-
+# menting the appropriate PNGLIB and ZLIB lines.
+
+!include <ntwin32.mak>
+
+
+# macros --------------------------------------------------------------------
+
+PNGPATH = ../libpng
+PNGINC = -I$(PNGPATH)
+#PNGLIB = $(PNGPATH)/pngdll.lib
+PNGLIB = $(PNGPATH)/libpng.lib
+
+ZPATH = ../zlib
+ZINC = -I$(ZPATH)
+#ZLIB = $(ZPATH)/zlibdll.lib
+ZLIB = $(ZPATH)/zlibstat.lib
+
+WINLIBS = -defaultlib:user32.lib gdi32.lib
+# ["real" apps may also need comctl32.lib, comdlg32.lib, winmm.lib, etc.]
+
+INCS = $(PNGINC) $(ZINC)
+RLIBS = $(PNGLIB) $(ZLIB) $(WINLIBS)
+WLIBS = $(PNGLIB) $(ZLIB)
+
+CC = cl
+LD = link
+RM = del
+CPPFLAGS = $(INCS)
+CFLAGS = -nologo -O -W3 $(cvars)
+# [note that -W3 is an MSVC-specific compilation flag ("all warnings on")]
+# [see %devstudio%\vc\include\win32.mak for cvars macro definition]
+O = .obj
+E = .exe
+
+RLDFLAGS = -nologo -subsystem:windows
+WLDFLAGS = -nologo
+
+RPNG = rpng-win
+RPNG2 = rpng2-win
+WPNG = wpng
+
+ROBJS = $(RPNG)$(O) readpng$(O)
+ROBJS2 = $(RPNG2)$(O) readpng2$(O)
+WOBJS = $(WPNG)$(O) writepng$(O)
+
+EXES = $(RPNG)$(E) $(RPNG2)$(E) $(WPNG)$(E)
+
+
+# implicit make rules -------------------------------------------------------
+
+.c$(O):
+ $(CC) -c $(CPPFLAGS) $(CFLAGS) $<
+
+
+# dependencies --------------------------------------------------------------
+
+all: $(EXES)
+
+$(RPNG)$(E): $(ROBJS)
+ $(LD) $(RLDFLAGS) -out:$@ $(ROBJS) $(RLIBS)
+
+$(RPNG2)$(E): $(ROBJS2)
+ $(LD) $(RLDFLAGS) -out:$@ $(ROBJS2) $(RLIBS)
+
+$(WPNG)$(E): $(WOBJS)
+ $(LD) $(WLDFLAGS) -out:$@ $(WOBJS) $(WLIBS)
+
+$(RPNG)$(O): $(RPNG).c readpng.h
+$(RPNG2)$(O): $(RPNG2).c readpng2.h
+$(WPNG)$(O): $(WPNG).c writepng.h
+
+readpng$(O): readpng.c readpng.h
+readpng2$(O): readpng2.c readpng2.h
+writepng$(O): writepng.c writepng.h
+
+
+# maintenance ---------------------------------------------------------------
+
+clean:
+# ideally we could just do this:
+# $(RM) $(EXES) $(ROBJS) $(ROBJS2) $(WOBJS)
+# ...but the Windows "DEL" command is none too bright, so:
+ $(RM) r*$(E)
+ $(RM) w*$(E)
+ $(RM) r*$(O)
+ $(RM) w*$(O)
diff --git a/libpng/contrib/gregbook/README b/libpng/contrib/gregbook/README
new file mode 100644
index 0000000..7b1f6a3
--- /dev/null
+++ b/libpng/contrib/gregbook/README
@@ -0,0 +1,186 @@
+ ===========================
+ PNG: The Definitive Guide
+ ===========================
+
+ Source Code
+
+Chapters 13, 14 and 15 of "PNG: The Definitive Guide" discuss three free,
+cross-platform demo programs that show how to use the libpng reference
+library: rpng, rpng2 and wpng. rpng and rpng2 are viewers; the first is
+a very simple example that that shows how a standard file-viewer might use
+libpng, while the second is designed to process streaming data and shows
+how a web browser might be written. wpng is a simple command-line program
+that reads binary PGM and PPM files (the ``raw'' grayscale and RGB subsets
+of PBMPLUS/NetPBM) and converts them to PNG.
+
+The source code for all three demo programs currently compiles under
+Unix, OpenVMS, and 32-bit Windows. (Special thanks to Martin Zinser,
+zinser@decus.de, for making the necessary changes for OpenVMS and for
+providing an appropriate build script.) Build instructions can be found
+below.
+
+Files:
+
+ README this file
+ LICENSE terms of distribution and reuse (BSD-like or GNU GPL)
+ COPYING GNU General Public License (GPL)
+
+ Makefile.unx Unix makefile
+ Makefile.w32 Windows (MSVC) makefile
+ makevms.com OpenVMS build script
+
+ rpng-win.c Windows front end for the basic viewer
+ rpng-x.c X Window System (Unix, OpenVMS) front end
+ readpng.c generic back end for the basic viewer
+ readpng.h header file for the basic viewer
+
+ rpng2-win.c Windows front end for the progressive viewer
+ rpng2-x.c X front end for the progressive viewer
+ readpng2.c generic back end for the progressive viewer
+ readpng2.h header file for the progressive viewer
+
+ wpng.c generic (text) front end for the converter
+ writepng.c generic back end for the converter
+ writepng.h header file for the converter
+
+ toucan.png transparent PNG for testing (by Stefan Schneider)
+
+Note that, although the programs are designed to be functional, their
+primary purpose is to illustrate how to use libpng to add PNG support to
+other programs. As such, their user interfaces are crude and definitely
+are not intended for everyday use.
+
+Please see http://www.libpng.org/pub/png/pngbook.html for further infor-
+mation and links to the latest version of the source code, and Chapters
+13-15 of the book for detailed discussion of the three programs.
+
+Greg Roelofs
+http://pobox.com/~newt/greg_contact.html
+16 March 2008
+
+
+BUILD INSTRUCTIONS
+
+ - Prerequisites (in order of compilation):
+
+ - zlib http://zlib.net/
+ - libpng http://www.libpng.org/pub/png/libpng.html
+ - pngbook http://www.libpng.org/pub/png/book/sources.html
+
+ The pngbook demo programs are explicitly designed to demonstrate proper
+ coding techniques for using the libpng reference library. As a result,
+ you need to download and build both zlib (on which libpng depends) and
+ libpng. A common build setup is to place the zlib, libpng and pngbook
+ subdirectory trees ("folders") in the same parent directory. Then the
+ libpng build can refer to files in ../zlib (or ..\zlib or [-.zlib]),
+ and similarly for the pngbook build.
+
+ Note that all three packages are designed to be built from a command
+ line by default; those who wish to use a graphical or other integrated
+ development environments are on their own.
+
+
+ - Unix:
+
+ Unpack the latest pngbook sources (which should correspond to this
+ README file) into a directory and change into that directory.
+
+ Copy Makefile.unx to Makefile and edit the PNG* and Z* variables
+ appropriately (possibly also the X* variables if necessary).
+
+ make
+
+ There is no "install" target, so copy the three executables somewhere
+ in your path or run them from the current directory. All three will
+ print a basic usage screen when run without any command-line arguments;
+ see the book for more details.
+
+
+ - Windows:
+
+ Unpack the latest pngbook sources (which should correspond to this
+ README file) into a folder, open a "DOS shell" or "command prompt"
+ or equivalent command-line window, and cd into the folder where you
+ unpacked the source code.
+
+ For MSVC, set up the necessary environment variables by invoking
+
+ %devstudio%\vc\bin\vcvars32.bat
+
+ where where %devstudio% is the installation directory for MSVC /
+ DevStudio. If you get "environment out of space" errors under 95/98,
+ create a desktop shortcut with "c:\windows\command.com /e:4096" as
+ the program command line and set the working directory to the pngbook
+ directory. Then double-click to open the new DOS-prompt window with
+ a bigger environment and retry the commands above.
+
+ Copy Makefile.w32 to Makefile and edit the PNGPATH and ZPATH variables
+ appropriately (possibly also the "INC" and "LIB" variables if needed).
+ Note that the names of the dynamic and static libpng and zlib libraries
+ used in the makefile may change in later releases of the libraries.
+ Also note that, as of libpng version 1.0.5, MSVC DLL builds do not work.
+ This makefile therefore builds statically linked executables, but if
+ the DLL problems ever get fixed, uncommenting the appropriate PNGLIB
+ and ZLIB lines will build dynamically linked executables instead.
+
+ Do the build by typing
+
+ nmake
+
+ The result should be three executables: rpng-win.exe, rpng2-win.exe,
+ and wpng.exe. Copy them somewhere in your PATH or run them from the
+ current folder. Like the Unix versions, the two windowed programs
+ (rpng and rpng2) now display a usage screen in a console window when
+ invoked without command-line arguments; this is new behavior as of
+ the June 2001 release. Note that the programs use the Unix-style "-"
+ character to specify options, instead of the more common DOS/Windows
+ "/" character. (For example: "rpng2-win -bgpat 4 foo.png", not
+ "rpng2-win /bgpat 4 foo.png")
+
+
+ - OpenVMS:
+
+ Unpack the pngbook sources into a subdirectory and change into that
+ subdirectory.
+
+ Edit makevms.com appropriately, specifically the zpath and pngpath
+ variables.
+
+ @makevms
+
+ To run the programs, they probably first need to be set up as "foreign
+ symbols," with "disk" and "dir" set appropriately:
+
+ $ rpng == "$disk:[dir]rpng-x.exe"
+ $ rpng2 == "$disk:[dir]rpng2-x.exe"
+ $ wpng == "$disk:[dir]wpng.exe"
+
+ All three will print a basic usage screen when run without any command-
+ line arguments; see the book for more details. Note that the options
+ style is Unix-like, i.e., preceded by "-" rather than "/".
+
+
+RUNNING THE PROGRAMS: (VERY) BRIEF INTRO
+
+ rpng is a simple PNG viewer that can display transparent PNGs with a
+ specified background color; for example,
+
+ rpng -bgcolor \#ff0000 toucan.png
+
+ would display the image with a red background. rpng2 is a progressive
+ viewer that simulates a web browser in some respects; it can display
+ images against either a background color or a dynamically generated
+ background image. For example:
+
+ rpng2 -bgpat 16 toucan.png
+
+ wpng is a purely command-line image converter from binary PBMPLUS/NetPBM
+ format (.pgm or .ppm) to PNG; for example,
+
+ wpng -time < toucan-notrans.ppm > toucan-notrans.png
+
+ would convert the specified PPM file (using redirection) to PNG, auto-
+ matically setting the PNG modification-time chunk.
+
+ All options can be abbreviated to the shortest unique value; for example,
+ "-bgc" for -bgcolor (versus "-bgp" for -bgpat), or "-g" for -gamma.
diff --git a/libpng/contrib/gregbook/makevms.com b/libpng/contrib/gregbook/makevms.com
new file mode 100644
index 0000000..f32bcab
--- /dev/null
+++ b/libpng/contrib/gregbook/makevms.com
@@ -0,0 +1,132 @@
+$!------------------------------------------------------------------------------
+$! make "PNG: The Definitive Guide" demo programs (for X) under OpenVMS
+$!
+$! Script created by Martin Zinser for libpng; modified by Greg Roelofs
+$! for standalone pngbook source distribution.
+$!
+$!
+$! Set locations where zlib and libpng sources live.
+$!
+$ zpath = ""
+$ pngpath = ""
+$!
+$ if f$search("[---.zlib]zlib.h").nes."" then zpath = "[---.zlib]"
+$ if f$search("[--]png.h").nes."" then pngpath = "[--]"
+$!
+$ if f$search("[-.zlib]zlib.h").nes."" then zpath = "[-.zlib]"
+$ if f$search("[-.libpng]png.h").nes."" then pngpath = "[-.libpng]"
+$!
+$ if zpath .eqs. ""
+$ then
+$ write sys$output "zlib include not found. Exiting..."
+$ exit 2
+$ endif
+$!
+$ if pngpath .eqs. ""
+$ then
+$ write sys$output "libpng include not found. Exiting..."
+$ exit 2
+$ endif
+$!
+$! Look for the compiler used.
+$!
+$ ccopt="/include=(''zpath',''pngpath')"
+$ if f$getsyi("HW_MODEL").ge.1024
+$ then
+$ ccopt = "/prefix=all"+ccopt
+$ comp = "__decc__=1"
+$ if f$trnlnm("SYS").eqs."" then define sys sys$library:
+$ else
+$ if f$search("SYS$SYSTEM:DECC$COMPILER.EXE").eqs.""
+$ then
+$ if f$trnlnm("SYS").eqs."" then define sys sys$library:
+$ if f$search("SYS$SYSTEM:VAXC.EXE").eqs.""
+$ then
+$ comp = "__gcc__=1"
+$ CC :== GCC
+$ else
+$ comp = "__vaxc__=1"
+$ endif
+$ else
+$ if f$trnlnm("SYS").eqs."" then define sys decc$library_include:
+$ ccopt = "/decc/prefix=all"+ccopt
+$ comp = "__decc__=1"
+$ endif
+$ endif
+$ open/write lopt lib.opt
+$ write lopt "''pngpath'libpng.olb/lib"
+$ write lopt "''zpath'libz.olb/lib"
+$ close lopt
+$ open/write xopt x11.opt
+$ write xopt "sys$library:decw$xlibshr.exe/share"
+$ close xopt
+$!
+$! Build 'em.
+$!
+$ write sys$output "Compiling PNG book programs ..."
+$ CALL MAKE readpng.OBJ "cc ''CCOPT' readpng" -
+ readpng.c readpng.h
+$ CALL MAKE readpng2.OBJ "cc ''CCOPT' readpng2" -
+ readpng2.c readpng2.h
+$ CALL MAKE writepng.OBJ "cc ''CCOPT' writepng" -
+ writepng.c writepng.h
+$ write sys$output "Building rpng-x..."
+$ CALL MAKE rpng-x.OBJ "cc ''CCOPT' rpng-x" -
+ rpng-x.c readpng.h
+$ call make rpng-x.exe -
+ "LINK rpng-x,readpng,lib.opt/opt,x11.opt/opt" -
+ rpng-x.obj readpng.obj
+$ write sys$output "Building rpng2-x..."
+$ CALL MAKE rpng2-x.OBJ "cc ''CCOPT' rpng2-x" -
+ rpng2-x.c readpng2.h
+$ call make rpng2-x.exe -
+ "LINK rpng2-x,readpng2,lib.opt/opt,x11.opt/opt" -
+ rpng2-x.obj readpng2.obj
+$ write sys$output "Building wpng..."
+$ CALL MAKE wpng.OBJ "cc ''CCOPT' wpng" -
+ wpng.c writepng.h
+$ call make wpng.exe -
+ "LINK wpng,writepng,lib.opt/opt" -
+ wpng.obj writepng.obj
+$ exit
+$!
+$!
+$MAKE: SUBROUTINE !SUBROUTINE TO CHECK DEPENDENCIES
+$ V = 'F$Verify(0)
+$! P1 = What we are trying to make
+$! P2 = Command to make it
+$! P3 - P8 What it depends on
+$
+$ If F$Search(P1) .Eqs. "" Then Goto Makeit
+$ Time = F$CvTime(F$File(P1,"RDT"))
+$arg=3
+$Loop:
+$ Argument = P'arg
+$ If Argument .Eqs. "" Then Goto Exit
+$ El=0
+$Loop2:
+$ File = F$Element(El," ",Argument)
+$ If File .Eqs. " " Then Goto Endl
+$ AFile = ""
+$Loop3:
+$ OFile = AFile
+$ AFile = F$Search(File)
+$ If AFile .Eqs. "" .Or. AFile .Eqs. OFile Then Goto NextEl
+$ If F$CvTime(F$File(AFile,"RDT")) .Ges. Time Then Goto Makeit
+$ Goto Loop3
+$NextEL:
+$ El = El + 1
+$ Goto Loop2
+$EndL:
+$ arg=arg+1
+$ If arg .Le. 8 Then Goto Loop
+$ Goto Exit
+$
+$Makeit:
+$ VV=F$VERIFY(0)
+$ write sys$output P2
+$ 'P2
+$ VV='F$Verify(VV)
+$Exit:
+$ If V Then Set Verify
+$ENDSUBROUTINE
diff --git a/libpng/contrib/gregbook/readpng.c b/libpng/contrib/gregbook/readpng.c
new file mode 100644
index 0000000..9167403
--- /dev/null
+++ b/libpng/contrib/gregbook/readpng.c
@@ -0,0 +1,317 @@
+/*---------------------------------------------------------------------------
+
+ rpng - simple PNG display program readpng.c
+
+ ---------------------------------------------------------------------------
+
+ Copyright (c) 1998-2007 Greg Roelofs. All rights reserved.
+
+ This software is provided "as is," without warranty of any kind,
+ express or implied. In no event shall the author or contributors
+ be held liable for any damages arising in any way from the use of
+ this software.
+
+ The contents of this file are DUAL-LICENSED. You may modify and/or
+ redistribute this software according to the terms of one of the
+ following two licenses (at your option):
+
+
+ LICENSE 1 ("BSD-like with advertising clause"):
+
+ Permission is granted to anyone to use this software for any purpose,
+ including commercial applications, and to alter it and redistribute
+ it freely, subject to the following restrictions:
+
+ 1. Redistributions of source code must retain the above copyright
+ notice, disclaimer, and this list of conditions.
+ 2. Redistributions in binary form must reproduce the above copyright
+ notice, disclaimer, and this list of conditions in the documenta-
+ tion and/or other materials provided with the distribution.
+ 3. All advertising materials mentioning features or use of this
+ software must display the following acknowledgment:
+
+ This product includes software developed by Greg Roelofs
+ and contributors for the book, "PNG: The Definitive Guide,"
+ published by O'Reilly and Associates.
+
+
+ LICENSE 2 (GNU GPL v2 or later):
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ ---------------------------------------------------------------------------*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <zlib.h>
+
+#include "png.h" /* libpng header */
+#include "readpng.h" /* typedefs, common macros, public prototypes */
+
+/* future versions of libpng will provide this macro: */
+#ifndef png_jmpbuf
+# define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
+#endif
+
+
+static png_structp png_ptr = NULL;
+static png_infop info_ptr = NULL;
+
+png_uint_32 width, height;
+int bit_depth, color_type;
+uch *image_data = NULL;
+
+
+void readpng_version_info(void)
+{
+ fprintf(stderr, " Compiled with libpng %s; using libpng %s.\n",
+ PNG_LIBPNG_VER_STRING, png_libpng_ver);
+ fprintf(stderr, " Compiled with zlib %s; using zlib %s.\n",
+ ZLIB_VERSION, zlib_version);
+}
+
+
+/* return value = 0 for success, 1 for bad sig, 2 for bad IHDR, 4 for no mem */
+
+int readpng_init(FILE *infile, ulg *pWidth, ulg *pHeight)
+{
+ uch sig[8];
+
+
+ /* first do a quick check that the file really is a PNG image; could
+ * have used slightly more general png_sig_cmp() function instead */
+
+ fread(sig, 1, 8, infile);
+ if (png_sig_cmp(sig, 0, 8))
+ return 1; /* bad signature */
+
+
+ /* could pass pointers to user-defined error handlers instead of NULLs: */
+
+ png_ptr = png_create_read_struct(png_get_libpng_ver(NULL), NULL, NULL,
+ NULL);
+ if (!png_ptr)
+ return 4; /* out of memory */
+
+ info_ptr = png_create_info_struct(png_ptr);
+ if (!info_ptr) {
+ png_destroy_read_struct(&png_ptr, NULL, NULL);
+ return 4; /* out of memory */
+ }
+
+
+ /* we could create a second info struct here (end_info), but it's only
+ * useful if we want to keep pre- and post-IDAT chunk info separated
+ * (mainly for PNG-aware image editors and converters) */
+
+
+ /* setjmp() must be called in every function that calls a PNG-reading
+ * libpng function */
+
+ if (setjmp(png_jmpbuf(png_ptr))) {
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+ return 2;
+ }
+
+
+ png_init_io(png_ptr, infile);
+ png_set_sig_bytes(png_ptr, 8); /* we already read the 8 signature bytes */
+
+ png_read_info(png_ptr, info_ptr); /* read all PNG info up to image data */
+
+
+ /* alternatively, could make separate calls to png_get_image_width(),
+ * etc., but want bit_depth and color_type for later [don't care about
+ * compression_type and filter_type => NULLs] */
+
+ png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
+ NULL, NULL, NULL);
+ *pWidth = width;
+ *pHeight = height;
+
+
+ /* OK, that's all we need for now; return happy */
+
+ return 0;
+}
+
+
+
+
+/* returns 0 if succeeds, 1 if fails due to no bKGD chunk, 2 if libpng error;
+ * scales values to 8-bit if necessary */
+
+int readpng_get_bgcolor(uch *red, uch *green, uch *blue)
+{
+ png_color_16p pBackground;
+
+
+ /* setjmp() must be called in every function that calls a PNG-reading
+ * libpng function */
+
+ if (setjmp(png_jmpbuf(png_ptr))) {
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+ return 2;
+ }
+
+
+ if (!png_get_valid(png_ptr, info_ptr, PNG_INFO_bKGD))
+ return 1;
+
+ /* it is not obvious from the libpng documentation, but this function
+ * takes a pointer to a pointer, and it always returns valid red, green
+ * and blue values, regardless of color_type: */
+
+ png_get_bKGD(png_ptr, info_ptr, &pBackground);
+
+
+ /* however, it always returns the raw bKGD data, regardless of any
+ * bit-depth transformations, so check depth and adjust if necessary */
+
+ if (bit_depth == 16) {
+ *red = pBackground->red >> 8;
+ *green = pBackground->green >> 8;
+ *blue = pBackground->blue >> 8;
+ } else if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8) {
+ if (bit_depth == 1)
+ *red = *green = *blue = pBackground->gray? 255 : 0;
+ else if (bit_depth == 2)
+ *red = *green = *blue = (255/3) * pBackground->gray;
+ else /* bit_depth == 4 */
+ *red = *green = *blue = (255/15) * pBackground->gray;
+ } else {
+ *red = (uch)pBackground->red;
+ *green = (uch)pBackground->green;
+ *blue = (uch)pBackground->blue;
+ }
+
+ return 0;
+}
+
+
+
+
+/* display_exponent == LUT_exponent * CRT_exponent */
+
+uch *readpng_get_image(double display_exponent, int *pChannels, ulg *pRowbytes)
+{
+ double gamma;
+ png_uint_32 i, rowbytes;
+ png_bytepp row_pointers = NULL;
+
+
+ /* setjmp() must be called in every function that calls a PNG-reading
+ * libpng function */
+
+ if (setjmp(png_jmpbuf(png_ptr))) {
+ free(image_data);
+ image_data = NULL;
+ free(row_pointers);
+ row_pointers = NULL;
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+ return NULL;
+ }
+
+
+ /* expand palette images to RGB, low-bit-depth grayscale images to 8 bits,
+ * transparency chunks to full alpha channel; strip 16-bit-per-sample
+ * images to 8 bits per sample; and convert grayscale to RGB[A] */
+
+ if (color_type == PNG_COLOR_TYPE_PALETTE)
+ png_set_expand(png_ptr);
+ if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
+ png_set_expand(png_ptr);
+ if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
+ png_set_expand(png_ptr);
+#ifdef PNG_READ_16_TO_8_SUPPORTED
+ if (bit_depth == 16)
+# ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
+ png_set_scale_16(png_ptr);
+# else
+ png_set_strip_16(png_ptr);
+# endif
+#endif
+ if (color_type == PNG_COLOR_TYPE_GRAY ||
+ color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+ png_set_gray_to_rgb(png_ptr);
+
+
+ /* unlike the example in the libpng documentation, we have *no* idea where
+ * this file may have come from--so if it doesn't have a file gamma, don't
+ * do any correction ("do no harm") */
+
+ if (png_get_gAMA(png_ptr, info_ptr, &gamma))
+ png_set_gamma(png_ptr, display_exponent, gamma);
+
+
+ /* all transformations have been registered; now update info_ptr data,
+ * get rowbytes and channels, and allocate image memory */
+
+ png_read_update_info(png_ptr, info_ptr);
+
+ *pRowbytes = rowbytes = png_get_rowbytes(png_ptr, info_ptr);
+ *pChannels = (int)png_get_channels(png_ptr, info_ptr);
+
+ if ((image_data = (uch *)malloc(rowbytes*height)) == NULL) {
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+ return NULL;
+ }
+ if ((row_pointers = (png_bytepp)malloc(height*sizeof(png_bytep))) == NULL) {
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+ free(image_data);
+ image_data = NULL;
+ return NULL;
+ }
+
+ Trace((stderr, "readpng_get_image: channels = %d, rowbytes = %ld, height = %ld\n",
+ *pChannels, rowbytes, height));
+
+
+ /* set the individual row_pointers to point at the correct offsets */
+
+ for (i = 0; i < height; ++i)
+ row_pointers[i] = image_data + i*rowbytes;
+
+
+ /* now we can go ahead and just read the whole image */
+
+ png_read_image(png_ptr, row_pointers);
+
+
+ /* and we're done! (png_read_end() can be omitted if no processing of
+ * post-IDAT text/time/etc. is desired) */
+
+ free(row_pointers);
+ row_pointers = NULL;
+
+ png_read_end(png_ptr, NULL);
+
+ return image_data;
+}
+
+
+void readpng_cleanup(int free_image_data)
+{
+ if (free_image_data && image_data) {
+ free(image_data);
+ image_data = NULL;
+ }
+
+ if (png_ptr && info_ptr) {
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+ png_ptr = NULL;
+ info_ptr = NULL;
+ }
+}
diff --git a/libpng/contrib/gregbook/readpng.h b/libpng/contrib/gregbook/readpng.h
new file mode 100644
index 0000000..fad9fe3
--- /dev/null
+++ b/libpng/contrib/gregbook/readpng.h
@@ -0,0 +1,88 @@
+/*---------------------------------------------------------------------------
+
+ rpng - simple PNG display program readpng.h
+
+ ---------------------------------------------------------------------------
+
+ Copyright (c) 1998-2007 Greg Roelofs. All rights reserved.
+
+ This software is provided "as is," without warranty of any kind,
+ express or implied. In no event shall the author or contributors
+ be held liable for any damages arising in any way from the use of
+ this software.
+
+ The contents of this file are DUAL-LICENSED. You may modify and/or
+ redistribute this software according to the terms of one of the
+ following two licenses (at your option):
+
+
+ LICENSE 1 ("BSD-like with advertising clause"):
+
+ Permission is granted to anyone to use this software for any purpose,
+ including commercial applications, and to alter it and redistribute
+ it freely, subject to the following restrictions:
+
+ 1. Redistributions of source code must retain the above copyright
+ notice, disclaimer, and this list of conditions.
+ 2. Redistributions in binary form must reproduce the above copyright
+ notice, disclaimer, and this list of conditions in the documenta-
+ tion and/or other materials provided with the distribution.
+ 3. All advertising materials mentioning features or use of this
+ software must display the following acknowledgment:
+
+ This product includes software developed by Greg Roelofs
+ and contributors for the book, "PNG: The Definitive Guide,"
+ published by O'Reilly and Associates.
+
+
+ LICENSE 2 (GNU GPL v2 or later):
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ ---------------------------------------------------------------------------*/
+
+#ifndef TRUE
+# define TRUE 1
+# define FALSE 0
+#endif
+
+#ifndef MAX
+# define MAX(a,b) ((a) > (b)? (a) : (b))
+# define MIN(a,b) ((a) < (b)? (a) : (b))
+#endif
+
+#ifdef DEBUG
+# define Trace(x) {fprintf x ; fflush(stderr); fflush(stdout);}
+#else
+# define Trace(x) ;
+#endif
+
+typedef unsigned char uch;
+typedef unsigned short ush;
+typedef unsigned long ulg;
+
+
+/* prototypes for public functions in readpng.c */
+
+void readpng_version_info(void);
+
+int readpng_init(FILE *infile, ulg *pWidth, ulg *pHeight);
+
+int readpng_get_bgcolor(uch *bg_red, uch *bg_green, uch *bg_blue);
+
+uch *readpng_get_image(double display_exponent, int *pChannels,
+ ulg *pRowbytes);
+
+void readpng_cleanup(int free_image_data);
diff --git a/libpng/contrib/gregbook/readpng2.c b/libpng/contrib/gregbook/readpng2.c
new file mode 100644
index 0000000..a9e7ba5
--- /dev/null
+++ b/libpng/contrib/gregbook/readpng2.c
@@ -0,0 +1,520 @@
+/*---------------------------------------------------------------------------
+
+ rpng2 - progressive-model PNG display program readpng2.c
+
+ ---------------------------------------------------------------------------
+
+ Copyright (c) 1998-2015 Greg Roelofs. All rights reserved.
+
+ This software is provided "as is," without warranty of any kind,
+ express or implied. In no event shall the author or contributors
+ be held liable for any damages arising in any way from the use of
+ this software.
+
+ The contents of this file are DUAL-LICENSED. You may modify and/or
+ redistribute this software according to the terms of one of the
+ following two licenses (at your option):
+
+
+ LICENSE 1 ("BSD-like with advertising clause"):
+
+ Permission is granted to anyone to use this software for any purpose,
+ including commercial applications, and to alter it and redistribute
+ it freely, subject to the following restrictions:
+
+ 1. Redistributions of source code must retain the above copyright
+ notice, disclaimer, and this list of conditions.
+ 2. Redistributions in binary form must reproduce the above copyright
+ notice, disclaimer, and this list of conditions in the documenta-
+ tion and/or other materials provided with the distribution.
+ 3. All advertising materials mentioning features or use of this
+ software must display the following acknowledgment:
+
+ This product includes software developed by Greg Roelofs
+ and contributors for the book, "PNG: The Definitive Guide,"
+ published by O'Reilly and Associates.
+
+
+ LICENSE 2 (GNU GPL v2 or later):
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ ---------------------------------------------------------------------------
+
+ Changelog:
+ %RDATE% - Check return value of png_get_bKGD() (Glenn R-P)
+
+ ---------------------------------------------------------------------------*/
+
+
+#include <stdlib.h> /* for exit() prototype */
+#include <setjmp.h>
+
+#include <zlib.h>
+#include "png.h" /* libpng header from the local directory */
+#include "readpng2.h" /* typedefs, common macros, public prototypes */
+
+
+/* local prototypes */
+
+static void readpng2_info_callback(png_structp png_ptr, png_infop info_ptr);
+static void readpng2_row_callback(png_structp png_ptr, png_bytep new_row,
+ png_uint_32 row_num, int pass);
+static void readpng2_end_callback(png_structp png_ptr, png_infop info_ptr);
+static void readpng2_error_handler(png_structp png_ptr, png_const_charp msg);
+static void readpng2_warning_handler(png_structp png_ptr, png_const_charp msg);
+
+
+
+
+void readpng2_version_info(void)
+{
+ fprintf(stderr, " Compiled with libpng %s; using libpng %s\n",
+ PNG_LIBPNG_VER_STRING, png_libpng_ver);
+
+ fprintf(stderr, " and with zlib %s; using zlib %s.\n",
+ ZLIB_VERSION, zlib_version);
+}
+
+
+
+
+int readpng2_check_sig(uch *sig, int num)
+{
+ return !png_sig_cmp(sig, 0, num);
+}
+
+
+
+
+/* returns 0 for success, 2 for libpng problem, 4 for out of memory */
+
+int readpng2_init(mainprog_info *mainprog_ptr)
+{
+ png_structp png_ptr; /* note: temporary variables! */
+ png_infop info_ptr;
+
+
+ /* could also replace libpng warning-handler (final NULL), but no need: */
+
+ png_ptr = png_create_read_struct(png_get_libpng_ver(NULL), mainprog_ptr,
+ readpng2_error_handler, readpng2_warning_handler);
+ if (!png_ptr)
+ return 4; /* out of memory */
+
+ info_ptr = png_create_info_struct(png_ptr);
+ if (!info_ptr) {
+ png_destroy_read_struct(&png_ptr, NULL, NULL);
+ return 4; /* out of memory */
+ }
+
+
+ /* we could create a second info struct here (end_info), but it's only
+ * useful if we want to keep pre- and post-IDAT chunk info separated
+ * (mainly for PNG-aware image editors and converters) */
+
+
+ /* setjmp() must be called in every function that calls a PNG-reading
+ * libpng function, unless an alternate error handler was installed--
+ * but compatible error handlers must either use longjmp() themselves
+ * (as in this program) or exit immediately, so here we are: */
+
+ if (setjmp(mainprog_ptr->jmpbuf)) {
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+ return 2;
+ }
+
+
+#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
+ /* prepare the reader to ignore all recognized chunks whose data won't be
+ * used, i.e., all chunks recognized by libpng except for IHDR, PLTE, IDAT,
+ * IEND, tRNS, bKGD, gAMA, and sRGB (small performance improvement) */
+ {
+ /* These byte strings were copied from png.h. If a future version
+ * of readpng2.c recognizes more chunks, add them to this list.
+ */
+ static PNG_CONST png_byte chunks_to_process[] = {
+ 98, 75, 71, 68, '\0', /* bKGD */
+ 103, 65, 77, 65, '\0', /* gAMA */
+ 115, 82, 71, 66, '\0', /* sRGB */
+ };
+
+ /* Ignore all chunks except for IHDR, PLTE, tRNS, IDAT, and IEND */
+ png_set_keep_unknown_chunks(png_ptr, -1 /* PNG_HANDLE_CHUNK_NEVER */,
+ NULL, -1);
+
+ /* But do not ignore chunks in the "chunks_to_process" list */
+ png_set_keep_unknown_chunks(png_ptr,
+ 0 /* PNG_HANDLE_CHUNK_AS_DEFAULT */, chunks_to_process,
+ sizeof(chunks_to_process)/5);
+ }
+#endif /* PNG_HANDLE_AS_UNKNOWN_SUPPORTED */
+
+
+ /* instead of doing png_init_io() here, now we set up our callback
+ * functions for progressive decoding */
+
+ png_set_progressive_read_fn(png_ptr, mainprog_ptr,
+ readpng2_info_callback, readpng2_row_callback, readpng2_end_callback);
+
+
+ /* make sure we save our pointers for use in readpng2_decode_data() */
+
+ mainprog_ptr->png_ptr = png_ptr;
+ mainprog_ptr->info_ptr = info_ptr;
+
+
+ /* and that's all there is to initialization */
+
+ return 0;
+}
+
+
+
+
+/* returns 0 for success, 2 for libpng (longjmp) problem */
+
+int readpng2_decode_data(mainprog_info *mainprog_ptr, uch *rawbuf, ulg length)
+{
+ png_structp png_ptr = (png_structp)mainprog_ptr->png_ptr;
+ png_infop info_ptr = (png_infop)mainprog_ptr->info_ptr;
+
+
+ /* setjmp() must be called in every function that calls a PNG-reading
+ * libpng function */
+
+ if (setjmp(mainprog_ptr->jmpbuf)) {
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+ mainprog_ptr->png_ptr = NULL;
+ mainprog_ptr->info_ptr = NULL;
+ return 2;
+ }
+
+
+ /* hand off the next chunk of input data to libpng for decoding */
+
+ png_process_data(png_ptr, info_ptr, rawbuf, length);
+
+ return 0;
+}
+
+
+
+
+static void readpng2_info_callback(png_structp png_ptr, png_infop info_ptr)
+{
+ mainprog_info *mainprog_ptr;
+ int color_type, bit_depth;
+ png_uint_32 width, height;
+#ifdef PNG_FLOATING_POINT_SUPPORTED
+ double gamma;
+#else
+ png_fixed_point gamma;
+#endif
+
+
+ /* setjmp() doesn't make sense here, because we'd either have to exit(),
+ * longjmp() ourselves, or return control to libpng, which doesn't want
+ * to see us again. By not doing anything here, libpng will instead jump
+ * to readpng2_decode_data(), which can return an error value to the main
+ * program. */
+
+
+ /* retrieve the pointer to our special-purpose struct, using the png_ptr
+ * that libpng passed back to us (i.e., not a global this time--there's
+ * no real difference for a single image, but for a multithreaded browser
+ * decoding several PNG images at the same time, one needs to avoid mixing
+ * up different images' structs) */
+
+ mainprog_ptr = png_get_progressive_ptr(png_ptr);
+
+ if (mainprog_ptr == NULL) { /* we be hosed */
+ fprintf(stderr,
+ "readpng2 error: main struct not recoverable in info_callback.\n");
+ fflush(stderr);
+ return;
+ /*
+ * Alternatively, we could call our error-handler just like libpng
+ * does, which would effectively terminate the program. Since this
+ * can only happen if png_ptr gets redirected somewhere odd or the
+ * main PNG struct gets wiped, we're probably toast anyway. (If
+ * png_ptr itself is NULL, we would not have been called.)
+ */
+ }
+
+
+ /* this is just like in the non-progressive case */
+
+ png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
+ NULL, NULL, NULL);
+ mainprog_ptr->width = (ulg)width;
+ mainprog_ptr->height = (ulg)height;
+
+
+ /* since we know we've read all of the PNG file's "header" (i.e., up
+ * to IDAT), we can check for a background color here */
+
+ if (mainprog_ptr->need_bgcolor)
+ {
+ png_color_16p pBackground;
+
+ /* it is not obvious from the libpng documentation, but this function
+ * takes a pointer to a pointer, and it always returns valid red,
+ * green and blue values, regardless of color_type: */
+ if (png_get_bKGD(png_ptr, info_ptr, &pBackground))
+ {
+
+ /* however, it always returns the raw bKGD data, regardless of any
+ * bit-depth transformations, so check depth and adjust if necessary
+ */
+ if (bit_depth == 16) {
+ mainprog_ptr->bg_red = pBackground->red >> 8;
+ mainprog_ptr->bg_green = pBackground->green >> 8;
+ mainprog_ptr->bg_blue = pBackground->blue >> 8;
+ } else if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8) {
+ if (bit_depth == 1)
+ mainprog_ptr->bg_red = mainprog_ptr->bg_green =
+ mainprog_ptr->bg_blue = pBackground->gray? 255 : 0;
+ else if (bit_depth == 2)
+ mainprog_ptr->bg_red = mainprog_ptr->bg_green =
+ mainprog_ptr->bg_blue = (255/3) * pBackground->gray;
+ else /* bit_depth == 4 */
+ mainprog_ptr->bg_red = mainprog_ptr->bg_green =
+ mainprog_ptr->bg_blue = (255/15) * pBackground->gray;
+ } else {
+ mainprog_ptr->bg_red = (uch)pBackground->red;
+ mainprog_ptr->bg_green = (uch)pBackground->green;
+ mainprog_ptr->bg_blue = (uch)pBackground->blue;
+ }
+ }
+ }
+
+
+ /* as before, let libpng expand palette images to RGB, low-bit-depth
+ * grayscale images to 8 bits, transparency chunks to full alpha channel;
+ * strip 16-bit-per-sample images to 8 bits per sample; and convert
+ * grayscale to RGB[A] */
+
+ if (color_type == PNG_COLOR_TYPE_PALETTE)
+ png_set_expand(png_ptr);
+ if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
+ png_set_expand(png_ptr);
+ if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
+ png_set_expand(png_ptr);
+#ifdef PNG_READ_16_TO_8_SUPPORTED
+ if (bit_depth == 16)
+# ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
+ png_set_scale_16(png_ptr);
+# else
+ png_set_strip_16(png_ptr);
+# endif
+#endif
+ if (color_type == PNG_COLOR_TYPE_GRAY ||
+ color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+ png_set_gray_to_rgb(png_ptr);
+
+
+ /* Unlike the basic viewer, which was designed to operate on local files,
+ * this program is intended to simulate a web browser--even though we
+ * actually read from a local file, too. But because we are pretending
+ * that most of the images originate on the Internet, we follow the recom-
+ * mendation of the sRGB proposal and treat unlabelled images (no gAMA
+ * chunk) as existing in the sRGB color space. That is, we assume that
+ * such images have a file gamma of 0.45455, which corresponds to a PC-like
+ * display system. This change in assumptions will have no effect on a
+ * PC-like system, but on a Mac, SGI, NeXT or other system with a non-
+ * identity lookup table, it will darken unlabelled images, which effec-
+ * tively favors images from PC-like systems over those originating on
+ * the local platform. Note that mainprog_ptr->display_exponent is the
+ * "gamma" value for the entire display system, i.e., the product of
+ * LUT_exponent and CRT_exponent. */
+
+#ifdef PNG_FLOATING_POINT_SUPPORTED
+ if (png_get_gAMA(png_ptr, info_ptr, &gamma))
+ png_set_gamma(png_ptr, mainprog_ptr->display_exponent, gamma);
+ else
+ png_set_gamma(png_ptr, mainprog_ptr->display_exponent, 0.45455);
+#else
+ if (png_get_gAMA_fixed(png_ptr, info_ptr, &gamma))
+ png_set_gamma_fixed(png_ptr,
+ (png_fixed_point)(100000*mainprog_ptr->display_exponent+.5), gamma);
+ else
+ png_set_gamma_fixed(png_ptr,
+ (png_fixed_point)(100000*mainprog_ptr->display_exponent+.5), 45455);
+#endif
+
+ /* we'll let libpng expand interlaced images, too */
+
+ mainprog_ptr->passes = png_set_interlace_handling(png_ptr);
+
+
+ /* all transformations have been registered; now update info_ptr data and
+ * then get rowbytes and channels */
+
+ png_read_update_info(png_ptr, info_ptr);
+
+ mainprog_ptr->rowbytes = (int)png_get_rowbytes(png_ptr, info_ptr);
+ mainprog_ptr->channels = png_get_channels(png_ptr, info_ptr);
+
+
+ /* Call the main program to allocate memory for the image buffer and
+ * initialize windows and whatnot. (The old-style function-pointer
+ * invocation is used for compatibility with a few supposedly ANSI
+ * compilers that nevertheless barf on "fn_ptr()"-style syntax.) */
+
+ (*mainprog_ptr->mainprog_init)();
+
+
+ /* and that takes care of initialization */
+
+ return;
+}
+
+
+
+
+
+static void readpng2_row_callback(png_structp png_ptr, png_bytep new_row,
+ png_uint_32 row_num, int pass)
+{
+ mainprog_info *mainprog_ptr;
+
+
+ /* first check whether the row differs from the previous pass; if not,
+ * nothing to combine or display */
+
+ if (!new_row)
+ return;
+
+
+ /* retrieve the pointer to our special-purpose struct so we can access
+ * the old rows and image-display callback function */
+
+ mainprog_ptr = png_get_progressive_ptr(png_ptr);
+
+
+ /* save the pass number for optional use by the front end */
+
+ mainprog_ptr->pass = pass;
+
+
+ /* have libpng either combine the new row data with the existing row data
+ * from previous passes (if interlaced) or else just copy the new row
+ * into the main program's image buffer */
+
+ png_progressive_combine_row(png_ptr, mainprog_ptr->row_pointers[row_num],
+ new_row);
+
+
+ /* finally, call the display routine in the main program with the number
+ * of the row we just updated */
+
+ (*mainprog_ptr->mainprog_display_row)(row_num);
+
+
+ /* and we're ready for more */
+
+ return;
+}
+
+
+
+
+
+static void readpng2_end_callback(png_structp png_ptr, png_infop info_ptr)
+{
+ mainprog_info *mainprog_ptr;
+
+
+ /* retrieve the pointer to our special-purpose struct */
+
+ mainprog_ptr = png_get_progressive_ptr(png_ptr);
+
+
+ /* let the main program know that it should flush any buffered image
+ * data to the display now and set a "done" flag or whatever, but note
+ * that it SHOULD NOT DESTROY THE PNG STRUCTS YET--in other words, do
+ * NOT call readpng2_cleanup() either here or in the finish_display()
+ * routine; wait until control returns to the main program via
+ * readpng2_decode_data() */
+
+ (*mainprog_ptr->mainprog_finish_display)();
+
+
+ /* all done */
+
+ (void)info_ptr; /* Unused */
+
+ return;
+}
+
+
+
+
+
+void readpng2_cleanup(mainprog_info *mainprog_ptr)
+{
+ png_structp png_ptr = (png_structp)mainprog_ptr->png_ptr;
+ png_infop info_ptr = (png_infop)mainprog_ptr->info_ptr;
+
+ if (png_ptr && info_ptr)
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+
+ mainprog_ptr->png_ptr = NULL;
+ mainprog_ptr->info_ptr = NULL;
+}
+
+
+static void readpng2_warning_handler(png_structp png_ptr, png_const_charp msg)
+{
+ fprintf(stderr, "readpng2 libpng warning: %s\n", msg);
+ fflush(stderr);
+ (void)png_ptr; /* Unused */
+}
+
+
+static void readpng2_error_handler(png_structp png_ptr, png_const_charp msg)
+{
+ mainprog_info *mainprog_ptr;
+
+ /* This function, aside from the extra step of retrieving the "error
+ * pointer" (below) and the fact that it exists within the application
+ * rather than within libpng, is essentially identical to libpng's
+ * default error handler. The second point is critical: since both
+ * setjmp() and longjmp() are called from the same code, they are
+ * guaranteed to have compatible notions of how big a jmp_buf is,
+ * regardless of whether _BSD_SOURCE or anything else has (or has not)
+ * been defined. */
+
+ fprintf(stderr, "readpng2 libpng error: %s\n", msg);
+ fflush(stderr);
+
+ mainprog_ptr = png_get_error_ptr(png_ptr);
+ if (mainprog_ptr == NULL) { /* we are completely hosed now */
+ fprintf(stderr,
+ "readpng2 severe error: jmpbuf not recoverable; terminating.\n");
+ fflush(stderr);
+ exit(99);
+ }
+
+ /* Now we have our data structure we can use the information in it
+ * to return control to our own higher level code (all the points
+ * where 'setjmp' is called in this file.) This will work with other
+ * error handling mechanisms as well - libpng always calls png_error
+ * when it can proceed no further, thus, so long as the error handler
+ * is intercepted, application code can do its own error recovery.
+ */
+ longjmp(mainprog_ptr->jmpbuf, 1);
+}
diff --git a/libpng/contrib/gregbook/readpng2.h b/libpng/contrib/gregbook/readpng2.h
new file mode 100644
index 0000000..6b3660d
--- /dev/null
+++ b/libpng/contrib/gregbook/readpng2.h
@@ -0,0 +1,116 @@
+/*---------------------------------------------------------------------------
+
+ rpng2 - progressive-model PNG display program readpng2.h
+
+ ---------------------------------------------------------------------------
+
+ Copyright (c) 1998-2008 Greg Roelofs. All rights reserved.
+
+ This software is provided "as is," without warranty of any kind,
+ express or implied. In no event shall the author or contributors
+ be held liable for any damages arising in any way from the use of
+ this software.
+
+ The contents of this file are DUAL-LICENSED. You may modify and/or
+ redistribute this software according to the terms of one of the
+ following two licenses (at your option):
+
+
+ LICENSE 1 ("BSD-like with advertising clause"):
+
+ Permission is granted to anyone to use this software for any purpose,
+ including commercial applications, and to alter it and redistribute
+ it freely, subject to the following restrictions:
+
+ 1. Redistributions of source code must retain the above copyright
+ notice, disclaimer, and this list of conditions.
+ 2. Redistributions in binary form must reproduce the above copyright
+ notice, disclaimer, and this list of conditions in the documenta-
+ tion and/or other materials provided with the distribution.
+ 3. All advertising materials mentioning features or use of this
+ software must display the following acknowledgment:
+
+ This product includes software developed by Greg Roelofs
+ and contributors for the book, "PNG: The Definitive Guide,"
+ published by O'Reilly and Associates.
+
+
+ LICENSE 2 (GNU GPL v2 or later):
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ ---------------------------------------------------------------------------*/
+
+#ifndef TRUE
+# define TRUE 1
+# define FALSE 0
+#endif
+
+#ifndef MAX
+# define MAX(a,b) ((a) > (b)? (a) : (b))
+# define MIN(a,b) ((a) < (b)? (a) : (b))
+#endif
+
+#ifdef DEBUG
+# define Trace(x) {fprintf x ; fflush(stderr); fflush(stdout);}
+#else
+# define Trace(x) ;
+#endif
+
+enum rpng2_states {
+ kPreInit = 0,
+ kWindowInit,
+ kDone
+};
+
+typedef unsigned char uch;
+typedef unsigned short ush;
+typedef unsigned long ulg;
+
+typedef struct _mainprog_info {
+ double display_exponent;
+ ulg width;
+ ulg height;
+ void *png_ptr;
+ void *info_ptr;
+ void (*mainprog_init)(void);
+ void (*mainprog_display_row)(ulg row_num);
+ void (*mainprog_finish_display)(void);
+ uch *image_data;
+ uch **row_pointers;
+ jmp_buf jmpbuf;
+ int passes; /* not used */
+ int pass;
+ int rowbytes;
+ int channels;
+ int need_bgcolor;
+ int state;
+ uch bg_red;
+ uch bg_green;
+ uch bg_blue;
+} mainprog_info;
+
+
+/* prototypes for public functions in readpng2.c */
+
+void readpng2_version_info(void);
+
+int readpng2_check_sig(uch *sig, int num);
+
+int readpng2_init(mainprog_info *mainprog_ptr);
+
+int readpng2_decode_data(mainprog_info *mainprog_ptr, uch *rawbuf, ulg length);
+
+void readpng2_cleanup(mainprog_info *mainprog_ptr);
diff --git a/libpng/contrib/gregbook/readppm.c b/libpng/contrib/gregbook/readppm.c
new file mode 100644
index 0000000..7fefc39
--- /dev/null
+++ b/libpng/contrib/gregbook/readppm.c
@@ -0,0 +1,183 @@
+/*---------------------------------------------------------------------------
+
+ rpng - simple PNG display program readppm.c
+
+ ---------------------------------------------------------------------------
+
+ This is a special-purpose replacement for readpng.c that allows binary
+ PPM files to be used in place of PNG images.
+
+ ---------------------------------------------------------------------------
+
+ Copyright (c) 1998-2007 Greg Roelofs. All rights reserved.
+
+ This software is provided "as is," without warranty of any kind,
+ express or implied. In no event shall the author or contributors
+ be held liable for any damages arising in any way from the use of
+ this software.
+
+ The contents of this file are DUAL-LICENSED. You may modify and/or
+ redistribute this software according to the terms of one of the
+ following two licenses (at your option):
+
+
+ LICENSE 1 ("BSD-like with advertising clause"):
+
+ Permission is granted to anyone to use this software for any purpose,
+ including commercial applications, and to alter it and redistribute
+ it freely, subject to the following restrictions:
+
+ 1. Redistributions of source code must retain the above copyright
+ notice, disclaimer, and this list of conditions.
+ 2. Redistributions in binary form must reproduce the above copyright
+ notice, disclaimer, and this list of conditions in the documenta-
+ tion and/or other materials provided with the distribution.
+ 3. All advertising materials mentioning features or use of this
+ software must display the following acknowledgment:
+
+ This product includes software developed by Greg Roelofs
+ and contributors for the book, "PNG: The Definitive Guide,"
+ published by O'Reilly and Associates.
+
+
+ LICENSE 2 (GNU GPL v2 or later):
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ ---------------------------------------------------------------------------*/
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "readpng.h" /* typedefs, common macros, public prototypes */
+
+
+ulg width, height;
+int bit_depth, color_type, channels;
+uch *image_data = NULL;
+FILE *saved_infile;
+
+
+void readpng_version_info()
+{
+ fprintf(stderr, " Compiled without libpng, zlib or PBMPLUS/NetPBM.\n");
+}
+
+
+/* return value = 0 for success, 1 for bad sig, 2 for bad IHDR, 4 for no mem */
+
+int readpng_init(FILE *infile, ulg *pWidth, ulg *pHeight)
+{
+ static uch ppmline[256];
+ int maxval;
+
+
+ saved_infile = infile;
+
+ fgets(ppmline, 256, infile);
+ if (ppmline[0] != 'P' || ppmline[1] != '6') {
+ fprintf(stderr, "ERROR: not a PPM file\n");
+ return 1;
+ }
+ /* possible color types: P5 = grayscale (0), P6 = RGB (2), P8 = RGBA (6) */
+ if (ppmline[1] == '6') {
+ color_type = 2;
+ channels = 3;
+ } else if (ppmline[1] == '8') {
+ color_type = 6;
+ channels = 4;
+ } else /* if (ppmline[1] == '5') */ {
+ color_type = 0;
+ channels = 1;
+ }
+
+ do {
+ fgets(ppmline, 256, infile);
+ } while (ppmline[0] == '#');
+ sscanf(ppmline, "%lu %lu", &width, &height);
+
+ do {
+ fgets(ppmline, 256, infile);
+ } while (ppmline[0] == '#');
+ sscanf(ppmline, "%d", &maxval);
+ if (maxval != 255) {
+ fprintf(stderr, "ERROR: maxval = %d\n", maxval);
+ return 2;
+ }
+ bit_depth = 8;
+
+ *pWidth = width;
+ *pHeight = height;
+
+ return 0;
+}
+
+
+
+
+/* returns 0 if succeeds, 1 if fails due to no bKGD chunk, 2 if libpng error;
+ * scales values to 8-bit if necessary */
+
+int readpng_get_bgcolor(uch *red, uch *green, uch *blue)
+{
+ return 1;
+}
+
+
+
+
+/* display_exponent == LUT_exponent * CRT_exponent */
+
+uch *readpng_get_image(double display_exponent, int *pChannels, ulg *pRowbytes)
+{
+ ulg rowbytes;
+
+
+ /* expand palette images to RGB, low-bit-depth grayscale images to 8 bits,
+ * transparency chunks to full alpha channel; strip 16-bit-per-sample
+ * images to 8 bits per sample; and convert grayscale to RGB[A] */
+
+ /* GRR WARNING: grayscale needs to be expanded and channels reset! */
+
+ *pRowbytes = rowbytes = channels*width;
+ *pChannels = channels;
+
+ if ((image_data = (uch *)malloc(rowbytes*height)) == NULL) {
+ return NULL;
+ }
+
+ Trace((stderr, "readpng_get_image: rowbytes = %ld, height = %ld\n", rowbytes, height));
+
+
+ /* now we can go ahead and just read the whole image */
+
+ if (fread(image_data, 1L, rowbytes*height, saved_infile) <
+ rowbytes*height) {
+ free (image_data);
+ image_data = NULL;
+ return NULL;
+ }
+
+ return image_data;
+}
+
+
+void readpng_cleanup(int free_image_data)
+{
+ if (free_image_data && image_data) {
+ free(image_data);
+ image_data = NULL;
+ }
+}
diff --git a/libpng/contrib/gregbook/rpng-win.c b/libpng/contrib/gregbook/rpng-win.c
new file mode 100644
index 0000000..f53ddc8
--- /dev/null
+++ b/libpng/contrib/gregbook/rpng-win.c
@@ -0,0 +1,728 @@
+/*---------------------------------------------------------------------------
+
+ rpng - simple PNG display program rpng-win.c
+
+ This program decodes and displays PNG images, with gamma correction and
+ optionally with a user-specified background color (in case the image has
+ transparency). It is very nearly the most basic PNG viewer possible.
+ This version is for 32-bit Windows; it may compile under 16-bit Windows
+ with a little tweaking (or maybe not).
+
+ to do:
+ - handle quoted command-line args (especially filenames with spaces)
+ - have minimum window width: oh well
+ - use %.1023s to simplify truncation of title-bar string?
+
+ ---------------------------------------------------------------------------
+
+ Changelog:
+ - 1.00: initial public release
+ - 1.01: modified to allow abbreviated options; fixed long/ulong mis-
+ match; switched to png_jmpbuf() macro
+ - 1.02: added extra set of parentheses to png_jmpbuf() macro; fixed
+ command-line parsing bug
+ - 1.10: enabled "message window"/console (thanks to David Geldreich)
+ - 2.00: dual-licensed (added GNU GPL)
+ - 2.01: fixed improper display of usage screen on PNG error(s)
+
+ ---------------------------------------------------------------------------
+
+ Copyright (c) 1998-2008 Greg Roelofs. All rights reserved.
+
+ This software is provided "as is," without warranty of any kind,
+ express or implied. In no event shall the author or contributors
+ be held liable for any damages arising in any way from the use of
+ this software.
+
+ The contents of this file are DUAL-LICENSED. You may modify and/or
+ redistribute this software according to the terms of one of the
+ following two licenses (at your option):
+
+
+ LICENSE 1 ("BSD-like with advertising clause"):
+
+ Permission is granted to anyone to use this software for any purpose,
+ including commercial applications, and to alter it and redistribute
+ it freely, subject to the following restrictions:
+
+ 1. Redistributions of source code must retain the above copyright
+ notice, disclaimer, and this list of conditions.
+ 2. Redistributions in binary form must reproduce the above copyright
+ notice, disclaimer, and this list of conditions in the documenta-
+ tion and/or other materials provided with the distribution.
+ 3. All advertising materials mentioning features or use of this
+ software must display the following acknowledgment:
+
+ This product includes software developed by Greg Roelofs
+ and contributors for the book, "PNG: The Definitive Guide,"
+ published by O'Reilly and Associates.
+
+
+ LICENSE 2 (GNU GPL v2 or later):
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ ---------------------------------------------------------------------------*/
+
+#define PROGNAME "rpng-win"
+#define LONGNAME "Simple PNG Viewer for Windows"
+#define VERSION "2.01 of 16 March 2008"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <windows.h>
+#ifdef __CYGWIN__
+/* getch replacement. Turns out, we don't really need this,
+ * but leave it here if we ever enable any of the uses of
+ * _getch in the main code
+ */
+#include <unistd.h>
+#include <termio.h>
+#include <sys/ioctl.h>
+int repl_getch( void )
+{
+ char ch;
+ int fd = fileno(stdin);
+ struct termio old_tty, new_tty;
+
+ ioctl(fd, TCGETA, &old_tty);
+ new_tty = old_tty;
+ new_tty.c_lflag &= ~(ICANON | ECHO | ISIG);
+ ioctl(fd, TCSETA, &new_tty);
+ fread(&ch, 1, sizeof(ch), stdin);
+ ioctl(fd, TCSETA, &old_tty);
+
+ return ch;
+}
+#define _getch repl_getch
+#else
+#include <conio.h> /* only for _getch() */
+#endif
+
+/* #define DEBUG : this enables the Trace() macros */
+
+#include "readpng.h" /* typedefs, common macros, readpng prototypes */
+
+
+/* could just include png.h, but this macro is the only thing we need
+ * (name and typedefs changed to local versions); note that side effects
+ * only happen with alpha (which could easily be avoided with
+ * "ush acopy = (alpha);") */
+
+#define alpha_composite(composite, fg, alpha, bg) { \
+ ush temp = ((ush)(fg)*(ush)(alpha) + \
+ (ush)(bg)*(ush)(255 - (ush)(alpha)) + (ush)128); \
+ (composite) = (uch)((temp + (temp >> 8)) >> 8); \
+}
+
+
+/* local prototypes */
+static int rpng_win_create_window(HINSTANCE hInst, int showmode);
+static int rpng_win_display_image(void);
+static void rpng_win_cleanup(void);
+LRESULT CALLBACK rpng_win_wndproc(HWND, UINT, WPARAM, LPARAM);
+
+
+static char titlebar[1024];
+static char *progname = PROGNAME;
+static char *appname = LONGNAME;
+static char *filename;
+static FILE *infile;
+
+static char *bgstr;
+static uch bg_red=0, bg_green=0, bg_blue=0;
+
+static double display_exponent;
+
+static ulg image_width, image_height, image_rowbytes;
+static int image_channels;
+static uch *image_data;
+
+/* Windows-specific variables */
+static ulg wimage_rowbytes;
+static uch *dib;
+static uch *wimage_data;
+static BITMAPINFOHEADER *bmih;
+
+static HWND global_hwnd;
+
+
+
+
+int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrevInst, PSTR cmd, int showmode)
+{
+ char *args[1024]; /* arbitrary limit, but should suffice */
+ char *p, *q, **argv = args;
+ int argc = 0;
+ int rc, alen, flen;
+ int error = 0;
+ int have_bg = FALSE;
+ double LUT_exponent; /* just the lookup table */
+ double CRT_exponent = 2.2; /* just the monitor */
+ double default_display_exponent; /* whole display system */
+ MSG msg;
+
+
+ filename = (char *)NULL;
+
+#ifndef __CYGWIN__
+ /* First reenable console output, which normally goes to the bit bucket
+ * for windowed apps. Closing the console window will terminate the
+ * app. Thanks to David.Geldreich@realviz.com for supplying the magical
+ * incantation. */
+
+ AllocConsole();
+ freopen("CONOUT$", "a", stderr);
+ freopen("CONOUT$", "a", stdout);
+#endif
+
+
+ /* Next set the default value for our display-system exponent, i.e.,
+ * the product of the CRT exponent and the exponent corresponding to
+ * the frame-buffer's lookup table (LUT), if any. This is not an
+ * exhaustive list of LUT values (e.g., OpenStep has a lot of weird
+ * ones), but it should cover 99% of the current possibilities. And
+ * yes, these ifdefs are completely wasted in a Windows program... */
+
+#if defined(NeXT)
+ LUT_exponent = 1.0 / 2.2;
+ /*
+ if (some_next_function_that_returns_gamma(&next_gamma))
+ LUT_exponent = 1.0 / next_gamma;
+ */
+#elif defined(sgi)
+ LUT_exponent = 1.0 / 1.7;
+ /* there doesn't seem to be any documented function to get the
+ * "gamma" value, so we do it the hard way */
+ infile = fopen("/etc/config/system.glGammaVal", "r");
+ if (infile) {
+ double sgi_gamma;
+
+ fgets(tmpline, 80, infile);
+ fclose(infile);
+ sgi_gamma = atof(tmpline);
+ if (sgi_gamma > 0.0)
+ LUT_exponent = 1.0 / sgi_gamma;
+ }
+#elif defined(Macintosh)
+ LUT_exponent = 1.8 / 2.61;
+ /*
+ if (some_mac_function_that_returns_gamma(&mac_gamma))
+ LUT_exponent = mac_gamma / 2.61;
+ */
+#else
+ LUT_exponent = 1.0; /* assume no LUT: most PCs */
+#endif
+
+ /* the defaults above give 1.0, 1.3, 1.5 and 2.2, respectively: */
+ default_display_exponent = LUT_exponent * CRT_exponent;
+
+
+ /* If the user has set the SCREEN_GAMMA environment variable as suggested
+ * (somewhat imprecisely) in the libpng documentation, use that; otherwise
+ * use the default value we just calculated. Either way, the user may
+ * override this via a command-line option. */
+
+ if ((p = getenv("SCREEN_GAMMA")) != NULL)
+ display_exponent = atof(p);
+ else
+ display_exponent = default_display_exponent;
+
+
+ /* Windows really hates command lines, so we have to set up our own argv.
+ * Note that we do NOT bother with quoted arguments here, so don't use
+ * filenames with spaces in 'em! */
+
+ argv[argc++] = PROGNAME;
+ p = cmd;
+ for (;;) {
+ if (*p == ' ')
+ while (*++p == ' ')
+ ;
+ /* now p points at the first non-space after some spaces */
+ if (*p == '\0')
+ break; /* nothing after the spaces: done */
+ argv[argc++] = q = p;
+ while (*q && *q != ' ')
+ ++q;
+ /* now q points at a space or the end of the string */
+ if (*q == '\0')
+ break; /* last argv already terminated; quit */
+ *q = '\0'; /* change space to terminator */
+ p = q + 1;
+ }
+ argv[argc] = NULL; /* terminate the argv array itself */
+
+
+ /* Now parse the command line for options and the PNG filename. */
+
+ while (*++argv && !error) {
+ if (!strncmp(*argv, "-gamma", 2)) {
+ if (!*++argv)
+ ++error;
+ else {
+ display_exponent = atof(*argv);
+ if (display_exponent <= 0.0)
+ ++error;
+ }
+ } else if (!strncmp(*argv, "-bgcolor", 2)) {
+ if (!*++argv)
+ ++error;
+ else {
+ bgstr = *argv;
+ if (strlen(bgstr) != 7 || bgstr[0] != '#')
+ ++error;
+ else
+ have_bg = TRUE;
+ }
+ } else {
+ if (**argv != '-') {
+ filename = *argv;
+ if (argv[1]) /* shouldn't be any more args after filename */
+ ++error;
+ } else
+ ++error; /* not expecting any other options */
+ }
+ }
+
+ if (!filename)
+ ++error;
+
+
+ /* print usage screen if any errors up to this point */
+
+ if (error) {
+#ifndef __CYGWIN__
+ int ch;
+#endif
+
+ fprintf(stderr, "\n%s %s: %s\n\n", PROGNAME, VERSION, appname);
+ readpng_version_info();
+ fprintf(stderr, "\n"
+ "Usage: %s [-gamma exp] [-bgcolor bg] file.png\n"
+ " exp \ttransfer-function exponent (``gamma'') of the display\n"
+ "\t\t system in floating-point format (e.g., ``%.1f''); equal\n"
+ "\t\t to the product of the lookup-table exponent (varies)\n"
+ "\t\t and the CRT exponent (usually 2.2); must be positive\n"
+ " bg \tdesired background color in 7-character hex RGB format\n"
+ "\t\t (e.g., ``#ff7700'' for orange: same as HTML colors);\n"
+ "\t\t used with transparent images\n"
+ "\nPress Q, Esc or mouse button 1 after image is displayed to quit.\n"
+#ifndef __CYGWIN__
+ "Press Q or Esc to quit this usage screen.\n"
+#endif
+ "\n", PROGNAME, default_display_exponent);
+#ifndef __CYGWIN__
+ do
+ ch = _getch();
+ while (ch != 'q' && ch != 'Q' && ch != 0x1B);
+#endif
+ exit(1);
+ }
+
+
+ if (!(infile = fopen(filename, "rb"))) {
+ fprintf(stderr, PROGNAME ": can't open PNG file [%s]\n", filename);
+ ++error;
+ } else {
+ if ((rc = readpng_init(infile, &image_width, &image_height)) != 0) {
+ switch (rc) {
+ case 1:
+ fprintf(stderr, PROGNAME
+ ": [%s] is not a PNG file: incorrect signature\n",
+ filename);
+ break;
+ case 2:
+ fprintf(stderr, PROGNAME
+ ": [%s] has bad IHDR (libpng longjmp)\n", filename);
+ break;
+ case 4:
+ fprintf(stderr, PROGNAME ": insufficient memory\n");
+ break;
+ default:
+ fprintf(stderr, PROGNAME
+ ": unknown readpng_init() error\n");
+ break;
+ }
+ ++error;
+ }
+ if (error)
+ fclose(infile);
+ }
+
+
+ if (error) {
+#ifndef __CYGWIN__
+ int ch;
+#endif
+
+ fprintf(stderr, PROGNAME ": aborting.\n");
+#ifndef __CYGWIN__
+ do
+ ch = _getch();
+ while (ch != 'q' && ch != 'Q' && ch != 0x1B);
+#endif
+ exit(2);
+ } else {
+ fprintf(stderr, "\n%s %s: %s\n", PROGNAME, VERSION, appname);
+#ifndef __CYGWIN__
+ fprintf(stderr,
+ "\n [console window: closing this window will terminate %s]\n\n",
+ PROGNAME);
+#endif
+ }
+
+
+ /* set the title-bar string, but make sure buffer doesn't overflow */
+
+ alen = strlen(appname);
+ flen = strlen(filename);
+ if (alen + flen + 3 > 1023)
+ sprintf(titlebar, "%s: ...%s", appname, filename+(alen+flen+6-1023));
+ else
+ sprintf(titlebar, "%s: %s", appname, filename);
+
+
+ /* if the user didn't specify a background color on the command line,
+ * check for one in the PNG file--if not, the initialized values of 0
+ * (black) will be used */
+
+ if (have_bg) {
+ unsigned r, g, b; /* this approach quiets compiler warnings */
+
+ sscanf(bgstr+1, "%2x%2x%2x", &r, &g, &b);
+ bg_red = (uch)r;
+ bg_green = (uch)g;
+ bg_blue = (uch)b;
+ } else if (readpng_get_bgcolor(&bg_red, &bg_green, &bg_blue) > 1) {
+ readpng_cleanup(TRUE);
+ fprintf(stderr, PROGNAME
+ ": libpng error while checking for background color\n");
+ exit(2);
+ }
+
+
+ /* do the basic Windows initialization stuff, make the window and fill it
+ * with the background color */
+
+ if (rpng_win_create_window(hInst, showmode))
+ exit(2);
+
+
+ /* decode the image, all at once */
+
+ Trace((stderr, "calling readpng_get_image()\n"))
+ image_data = readpng_get_image(display_exponent, &image_channels,
+ &image_rowbytes);
+ Trace((stderr, "done with readpng_get_image()\n"))
+
+
+ /* done with PNG file, so clean up to minimize memory usage (but do NOT
+ * nuke image_data!) */
+
+ readpng_cleanup(FALSE);
+ fclose(infile);
+
+ if (!image_data) {
+ fprintf(stderr, PROGNAME ": unable to decode PNG image\n");
+ exit(3);
+ }
+
+
+ /* display image (composite with background if requested) */
+
+ Trace((stderr, "calling rpng_win_display_image()\n"))
+ if (rpng_win_display_image()) {
+ free(image_data);
+ exit(4);
+ }
+ Trace((stderr, "done with rpng_win_display_image()\n"))
+
+
+ /* wait for the user to tell us when to quit */
+
+ printf(
+#ifndef __CYGWIN__
+ "Done. Press Q, Esc or mouse button 1 (within image window) to quit.\n"
+#else
+ "Done. Press mouse button 1 (within image window) to quit.\n"
+#endif
+ );
+ fflush(stdout);
+
+ while (GetMessage(&msg, NULL, 0, 0)) {
+ TranslateMessage(&msg);
+ DispatchMessage(&msg);
+ }
+
+
+ /* OK, we're done: clean up all image and Windows resources and go away */
+
+ rpng_win_cleanup();
+
+ return msg.wParam;
+}
+
+
+
+
+
+static int rpng_win_create_window(HINSTANCE hInst, int showmode)
+{
+ uch *dest;
+ int extra_width, extra_height;
+ ulg i, j;
+ WNDCLASSEX wndclass;
+
+
+/*---------------------------------------------------------------------------
+ Allocate memory for the display-specific version of the image (round up
+ to multiple of 4 for Windows DIB).
+ ---------------------------------------------------------------------------*/
+
+ wimage_rowbytes = ((3*image_width + 3L) >> 2) << 2;
+
+ if (!(dib = (uch *)malloc(sizeof(BITMAPINFOHEADER) +
+ wimage_rowbytes*image_height)))
+ {
+ return 4; /* fail */
+ }
+
+/*---------------------------------------------------------------------------
+ Initialize the DIB. Negative height means to use top-down BMP ordering
+ (must be uncompressed, but that's what we want). Bit count of 1, 4 or 8
+ implies a colormap of RGBX quads, but 24-bit BMPs just use B,G,R values
+ directly => wimage_data begins immediately after BMP header.
+ ---------------------------------------------------------------------------*/
+
+ memset(dib, 0, sizeof(BITMAPINFOHEADER));
+ bmih = (BITMAPINFOHEADER *)dib;
+ bmih->biSize = sizeof(BITMAPINFOHEADER);
+ bmih->biWidth = image_width;
+ bmih->biHeight = -((long)image_height);
+ bmih->biPlanes = 1;
+ bmih->biBitCount = 24;
+ bmih->biCompression = 0;
+ wimage_data = dib + sizeof(BITMAPINFOHEADER);
+
+/*---------------------------------------------------------------------------
+ Fill in background color (black by default); data are in BGR order.
+ ---------------------------------------------------------------------------*/
+
+ for (j = 0; j < image_height; ++j) {
+ dest = wimage_data + j*wimage_rowbytes;
+ for (i = image_width; i > 0; --i) {
+ *dest++ = bg_blue;
+ *dest++ = bg_green;
+ *dest++ = bg_red;
+ }
+ }
+
+/*---------------------------------------------------------------------------
+ Set the window parameters.
+ ---------------------------------------------------------------------------*/
+
+ memset(&wndclass, 0, sizeof(wndclass));
+
+ wndclass.cbSize = sizeof(wndclass);
+ wndclass.style = CS_HREDRAW | CS_VREDRAW;
+ wndclass.lpfnWndProc = rpng_win_wndproc;
+ wndclass.hInstance = hInst;
+ wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
+ wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);
+ wndclass.hbrBackground = (HBRUSH)GetStockObject(DKGRAY_BRUSH);
+ wndclass.lpszMenuName = NULL;
+ wndclass.lpszClassName = progname;
+ wndclass.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
+
+ RegisterClassEx(&wndclass);
+
+/*---------------------------------------------------------------------------
+ Finally, create the window.
+ ---------------------------------------------------------------------------*/
+
+ extra_width = 2*(GetSystemMetrics(SM_CXBORDER) +
+ GetSystemMetrics(SM_CXDLGFRAME));
+ extra_height = 2*(GetSystemMetrics(SM_CYBORDER) +
+ GetSystemMetrics(SM_CYDLGFRAME)) +
+ GetSystemMetrics(SM_CYCAPTION);
+
+ global_hwnd = CreateWindow(progname, titlebar, WS_OVERLAPPEDWINDOW,
+ CW_USEDEFAULT, CW_USEDEFAULT, image_width+extra_width,
+ image_height+extra_height, NULL, NULL, hInst, NULL);
+
+ ShowWindow(global_hwnd, showmode);
+ UpdateWindow(global_hwnd);
+
+ return 0;
+
+} /* end function rpng_win_create_window() */
+
+
+
+
+
+static int rpng_win_display_image()
+{
+ uch *src, *dest;
+ uch r, g, b, a;
+ ulg i, row, lastrow;
+ RECT rect;
+
+
+ Trace((stderr, "beginning display loop (image_channels == %d)\n",
+ image_channels))
+ Trace((stderr, "(width = %ld, rowbytes = %ld, wimage_rowbytes = %d)\n",
+ image_width, image_rowbytes, wimage_rowbytes))
+
+
+/*---------------------------------------------------------------------------
+ Blast image data to buffer. This whole routine takes place before the
+ message loop begins, so there's no real point in any pseudo-progressive
+ display...
+ ---------------------------------------------------------------------------*/
+
+ for (lastrow = row = 0; row < image_height; ++row) {
+ src = image_data + row*image_rowbytes;
+ dest = wimage_data + row*wimage_rowbytes;
+ if (image_channels == 3) {
+ for (i = image_width; i > 0; --i) {
+ r = *src++;
+ g = *src++;
+ b = *src++;
+ *dest++ = b;
+ *dest++ = g; /* note reverse order */
+ *dest++ = r;
+ }
+ } else /* if (image_channels == 4) */ {
+ for (i = image_width; i > 0; --i) {
+ r = *src++;
+ g = *src++;
+ b = *src++;
+ a = *src++;
+ if (a == 255) {
+ *dest++ = b;
+ *dest++ = g;
+ *dest++ = r;
+ } else if (a == 0) {
+ *dest++ = bg_blue;
+ *dest++ = bg_green;
+ *dest++ = bg_red;
+ } else {
+ /* this macro (copied from png.h) composites the
+ * foreground and background values and puts the
+ * result into the first argument; there are no
+ * side effects with the first argument */
+ alpha_composite(*dest++, b, a, bg_blue);
+ alpha_composite(*dest++, g, a, bg_green);
+ alpha_composite(*dest++, r, a, bg_red);
+ }
+ }
+ }
+ /* display after every 16 lines */
+ if (((row+1) & 0xf) == 0) {
+ rect.left = 0L;
+ rect.top = (LONG)lastrow;
+ rect.right = (LONG)image_width; /* possibly off by one? */
+ rect.bottom = (LONG)lastrow + 16L; /* possibly off by one? */
+ InvalidateRect(global_hwnd, &rect, FALSE);
+ UpdateWindow(global_hwnd); /* similar to XFlush() */
+ lastrow = row + 1;
+ }
+ }
+
+ Trace((stderr, "calling final image-flush routine\n"))
+ if (lastrow < image_height) {
+ rect.left = 0L;
+ rect.top = (LONG)lastrow;
+ rect.right = (LONG)image_width; /* possibly off by one? */
+ rect.bottom = (LONG)image_height; /* possibly off by one? */
+ InvalidateRect(global_hwnd, &rect, FALSE);
+ UpdateWindow(global_hwnd); /* similar to XFlush() */
+ }
+
+/*
+ last param determines whether or not background is wiped before paint
+ InvalidateRect(global_hwnd, NULL, TRUE);
+ UpdateWindow(global_hwnd);
+ */
+
+ return 0;
+}
+
+
+
+
+
+static void rpng_win_cleanup()
+{
+ if (image_data) {
+ free(image_data);
+ image_data = NULL;
+ }
+
+ if (dib) {
+ free(dib);
+ dib = NULL;
+ }
+}
+
+
+
+
+
+LRESULT CALLBACK rpng_win_wndproc(HWND hwnd, UINT iMsg, WPARAM wP, LPARAM lP)
+{
+ HDC hdc;
+ PAINTSTRUCT ps;
+ int rc;
+
+ switch (iMsg) {
+ case WM_CREATE:
+ /* one-time processing here, if any */
+ return 0;
+
+ case WM_PAINT:
+ hdc = BeginPaint(hwnd, &ps);
+ /* dest */
+ rc = StretchDIBits(hdc, 0, 0, image_width, image_height,
+ /* source */
+ 0, 0, image_width, image_height,
+ wimage_data, (BITMAPINFO *)bmih,
+ /* iUsage: no clue */
+ 0, SRCCOPY);
+ EndPaint(hwnd, &ps);
+ return 0;
+
+ /* wait for the user to tell us when to quit */
+ case WM_CHAR:
+ switch (wP) { /* only need one, so ignore repeat count */
+ case 'q':
+ case 'Q':
+ case 0x1B: /* Esc key */
+ PostQuitMessage(0);
+ }
+ return 0;
+
+ case WM_LBUTTONDOWN: /* another way of quitting */
+ case WM_DESTROY:
+ PostQuitMessage(0);
+ return 0;
+ }
+
+ return DefWindowProc(hwnd, iMsg, wP, lP);
+}
diff --git a/libpng/contrib/gregbook/rpng-x.c b/libpng/contrib/gregbook/rpng-x.c
new file mode 100644
index 0000000..ddd7c58
--- /dev/null
+++ b/libpng/contrib/gregbook/rpng-x.c
@@ -0,0 +1,910 @@
+/*---------------------------------------------------------------------------
+
+ rpng - simple PNG display program rpng-x.c
+
+ This program decodes and displays PNG images, with gamma correction and
+ optionally with a user-specified background color (in case the image has
+ transparency). It is very nearly the most basic PNG viewer possible.
+ This version is for the X Window System (tested by author under Unix and
+ by Martin Zinser under OpenVMS; may work under OS/2 with some tweaking).
+
+ to do:
+ - 8-bit (colormapped) X support
+ - use %.1023s to simplify truncation of title-bar string?
+
+ ---------------------------------------------------------------------------
+
+ Changelog:
+ - 1.01: initial public release
+ - 1.02: modified to allow abbreviated options; fixed long/ulong mis-
+ match; switched to png_jmpbuf() macro
+ - 1.10: added support for non-default visuals; fixed X pixel-conversion
+ - 1.11: added extra set of parentheses to png_jmpbuf() macro; fixed
+ command-line parsing bug
+ - 1.12: fixed some small X memory leaks (thanks to François Petitjean)
+ - 1.13: fixed XFreeGC() crash bug (thanks to Patrick Welche)
+ - 1.14: added support for X resources (thanks to Gerhard Niklasch)
+ - 2.00: dual-licensed (added GNU GPL)
+ - 2.01: fixed improper display of usage screen on PNG error(s)
+ - 2.02: Added "void(argc);" statement to quiet pedantic compiler warnings
+ about unused variable (GR-P)
+
+ ---------------------------------------------------------------------------
+
+ Copyright (c) 1998-2008 Greg Roelofs. All rights reserved.
+
+ This software is provided "as is," without warranty of any kind,
+ express or implied. In no event shall the author or contributors
+ be held liable for any damages arising in any way from the use of
+ this software.
+
+ The contents of this file are DUAL-LICENSED. You may modify and/or
+ redistribute this software according to the terms of one of the
+ following two licenses (at your option):
+
+
+ LICENSE 1 ("BSD-like with advertising clause"):
+
+ Permission is granted to anyone to use this software for any purpose,
+ including commercial applications, and to alter it and redistribute
+ it freely, subject to the following restrictions:
+
+ 1. Redistributions of source code must retain the above copyright
+ notice, disclaimer, and this list of conditions.
+ 2. Redistributions in binary form must reproduce the above copyright
+ notice, disclaimer, and this list of conditions in the documenta-
+ tion and/or other materials provided with the distribution.
+ 3. All advertising materials mentioning features or use of this
+ software must display the following acknowledgment:
+
+ This product includes software developed by Greg Roelofs
+ and contributors for the book, "PNG: The Definitive Guide,"
+ published by O'Reilly and Associates.
+
+
+ LICENSE 2 (GNU GPL v2 or later):
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ ---------------------------------------------------------------------------*/
+
+#define PROGNAME "rpng-x"
+#define LONGNAME "Simple PNG Viewer for X"
+#define VERSION "2.02 of 15 June 2014"
+#define RESNAME "rpng" /* our X resource application name */
+#define RESCLASS "Rpng" /* our X resource class name */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+#include <X11/Xos.h>
+#include <X11/keysym.h>
+
+/* #define DEBUG : this enables the Trace() macros */
+
+#include "readpng.h" /* typedefs, common macros, readpng prototypes */
+
+
+/* could just include png.h, but this macro is the only thing we need
+ * (name and typedefs changed to local versions); note that side effects
+ * only happen with alpha (which could easily be avoided with
+ * "ush acopy = (alpha);") */
+
+#define alpha_composite(composite, fg, alpha, bg) { \
+ ush temp = ((ush)(fg)*(ush)(alpha) + \
+ (ush)(bg)*(ush)(255 - (ush)(alpha)) + (ush)128); \
+ (composite) = (uch)((temp + (temp >> 8)) >> 8); \
+}
+
+
+/* local prototypes */
+static int rpng_x_create_window(void);
+static int rpng_x_display_image(void);
+static void rpng_x_cleanup(void);
+static int rpng_x_msb(ulg u32val);
+
+
+static char titlebar[1024], *window_name = titlebar;
+static char *appname = LONGNAME;
+static char *icon_name = PROGNAME;
+static char *res_name = RESNAME;
+static char *res_class = RESCLASS;
+static char *filename;
+static FILE *infile;
+
+static char *bgstr;
+static uch bg_red=0, bg_green=0, bg_blue=0;
+
+static double display_exponent;
+
+static ulg image_width, image_height, image_rowbytes;
+static int image_channels;
+static uch *image_data;
+
+/* X-specific variables */
+static char *displayname;
+static XImage *ximage;
+static Display *display;
+static int depth;
+static Visual *visual;
+static XVisualInfo *visual_list;
+static int RShift, GShift, BShift;
+static ulg RMask, GMask, BMask;
+static Window window;
+static GC gc;
+static Colormap colormap;
+
+static int have_nondefault_visual = FALSE;
+static int have_colormap = FALSE;
+static int have_window = FALSE;
+static int have_gc = FALSE;
+/*
+ulg numcolors=0, pixels[256];
+ush reds[256], greens[256], blues[256];
+ */
+
+
+
+
+int main(int argc, char **argv)
+{
+#ifdef sgi
+ char tmpline[80];
+#endif
+ char *p;
+ int rc, alen, flen;
+ int error = 0;
+ int have_bg = FALSE;
+ double LUT_exponent; /* just the lookup table */
+ double CRT_exponent = 2.2; /* just the monitor */
+ double default_display_exponent; /* whole display system */
+ XEvent e;
+ KeySym k;
+
+
+ displayname = (char *)NULL;
+ filename = (char *)NULL;
+
+
+ /* First set the default value for our display-system exponent, i.e.,
+ * the product of the CRT exponent and the exponent corresponding to
+ * the frame-buffer's lookup table (LUT), if any. This is not an
+ * exhaustive list of LUT values (e.g., OpenStep has a lot of weird
+ * ones), but it should cover 99% of the current possibilities. */
+
+#if defined(NeXT)
+ LUT_exponent = 1.0 / 2.2;
+ /*
+ if (some_next_function_that_returns_gamma(&next_gamma))
+ LUT_exponent = 1.0 / next_gamma;
+ */
+#elif defined(sgi)
+ LUT_exponent = 1.0 / 1.7;
+ /* there doesn't seem to be any documented function to get the
+ * "gamma" value, so we do it the hard way */
+ infile = fopen("/etc/config/system.glGammaVal", "r");
+ if (infile) {
+ double sgi_gamma;
+
+ fgets(tmpline, 80, infile);
+ fclose(infile);
+ sgi_gamma = atof(tmpline);
+ if (sgi_gamma > 0.0)
+ LUT_exponent = 1.0 / sgi_gamma;
+ }
+#elif defined(Macintosh)
+ LUT_exponent = 1.8 / 2.61;
+ /*
+ if (some_mac_function_that_returns_gamma(&mac_gamma))
+ LUT_exponent = mac_gamma / 2.61;
+ */
+#else
+ LUT_exponent = 1.0; /* assume no LUT: most PCs */
+#endif
+
+ /* the defaults above give 1.0, 1.3, 1.5 and 2.2, respectively: */
+ default_display_exponent = LUT_exponent * CRT_exponent;
+
+
+ /* If the user has set the SCREEN_GAMMA environment variable as suggested
+ * (somewhat imprecisely) in the libpng documentation, use that; otherwise
+ * use the default value we just calculated. Either way, the user may
+ * override this via a command-line option. */
+
+ if ((p = getenv("SCREEN_GAMMA")) != NULL)
+ display_exponent = atof(p);
+ else
+ display_exponent = default_display_exponent;
+
+
+ /* Now parse the command line for options and the PNG filename. */
+
+ while (*++argv && !error) {
+ if (!strncmp(*argv, "-display", 2)) {
+ if (!*++argv)
+ ++error;
+ else
+ displayname = *argv;
+ } else if (!strncmp(*argv, "-gamma", 2)) {
+ if (!*++argv)
+ ++error;
+ else {
+ display_exponent = atof(*argv);
+ if (display_exponent <= 0.0)
+ ++error;
+ }
+ } else if (!strncmp(*argv, "-bgcolor", 2)) {
+ if (!*++argv)
+ ++error;
+ else {
+ bgstr = *argv;
+ if (strlen(bgstr) != 7 || bgstr[0] != '#')
+ ++error;
+ else
+ have_bg = TRUE;
+ }
+ } else {
+ if (**argv != '-') {
+ filename = *argv;
+ if (argv[1]) /* shouldn't be any more args after filename */
+ ++error;
+ } else
+ ++error; /* not expecting any other options */
+ }
+ }
+
+ if (!filename)
+ ++error;
+
+
+ /* print usage screen if any errors up to this point */
+
+ if (error) {
+ fprintf(stderr, "\n%s %s: %s\n", PROGNAME, VERSION, appname);
+ readpng_version_info();
+ fprintf(stderr, "\n"
+ "Usage: %s [-display xdpy] [-gamma exp] [-bgcolor bg] file.png\n"
+ " xdpy\tname of the target X display (e.g., ``hostname:0'')\n"
+ " exp \ttransfer-function exponent (``gamma'') of the display\n"
+ "\t\t system in floating-point format (e.g., ``%.1f''); equal\n",
+ PROGNAME, default_display_exponent);
+
+ fprintf(stderr, "\n"
+ "\t\t to the product of the lookup-table exponent (varies)\n"
+ "\t\t and the CRT exponent (usually 2.2); must be positive\n"
+ " bg \tdesired background color in 7-character hex RGB format\n"
+ "\t\t (e.g., ``#ff7700'' for orange: same as HTML colors);\n"
+ "\t\t used with transparent images\n"
+ "\nPress Q, Esc or mouse button 1 (within image window, after image\n"
+ "is displayed) to quit.\n");
+ exit(1);
+ }
+
+
+ if (!(infile = fopen(filename, "rb"))) {
+ fprintf(stderr, PROGNAME ": can't open PNG file [%s]\n", filename);
+ ++error;
+ } else {
+ if ((rc = readpng_init(infile, &image_width, &image_height)) != 0) {
+ switch (rc) {
+ case 1:
+ fprintf(stderr, PROGNAME
+ ": [%s] is not a PNG file: incorrect signature\n",
+ filename);
+ break;
+ case 2:
+ fprintf(stderr, PROGNAME
+ ": [%s] has bad IHDR (libpng longjmp)\n", filename);
+ break;
+ case 4:
+ fprintf(stderr, PROGNAME ": insufficient memory\n");
+ break;
+ default:
+ fprintf(stderr, PROGNAME
+ ": unknown readpng_init() error\n");
+ break;
+ }
+ ++error;
+ } else {
+ display = XOpenDisplay(displayname);
+ if (!display) {
+ readpng_cleanup(TRUE);
+ fprintf(stderr, PROGNAME ": can't open X display [%s]\n",
+ displayname? displayname : "default");
+ ++error;
+ }
+ }
+ if (error)
+ fclose(infile);
+ }
+
+
+ if (error) {
+ fprintf(stderr, PROGNAME ": aborting.\n");
+ exit(2);
+ }
+
+
+ /* set the title-bar string, but make sure buffer doesn't overflow */
+
+ alen = strlen(appname);
+ flen = strlen(filename);
+ if (alen + flen + 3 > 1023)
+ sprintf(titlebar, "%s: ...%s", appname, filename+(alen+flen+6-1023));
+ else
+ sprintf(titlebar, "%s: %s", appname, filename);
+
+
+ /* if the user didn't specify a background color on the command line,
+ * check for one in the PNG file--if not, the initialized values of 0
+ * (black) will be used */
+
+ if (have_bg) {
+ unsigned r, g, b; /* this approach quiets compiler warnings */
+
+ sscanf(bgstr+1, "%2x%2x%2x", &r, &g, &b);
+ bg_red = (uch)r;
+ bg_green = (uch)g;
+ bg_blue = (uch)b;
+ } else if (readpng_get_bgcolor(&bg_red, &bg_green, &bg_blue) > 1) {
+ readpng_cleanup(TRUE);
+ fprintf(stderr, PROGNAME
+ ": libpng error while checking for background color\n");
+ exit(2);
+ }
+
+
+ /* do the basic X initialization stuff, make the window and fill it
+ * with the background color */
+
+ if (rpng_x_create_window())
+ exit(2);
+
+
+ /* decode the image, all at once */
+
+ Trace((stderr, "calling readpng_get_image()\n"))
+ image_data = readpng_get_image(display_exponent, &image_channels,
+ &image_rowbytes);
+ Trace((stderr, "done with readpng_get_image()\n"))
+
+
+ /* done with PNG file, so clean up to minimize memory usage (but do NOT
+ * nuke image_data!) */
+
+ readpng_cleanup(FALSE);
+ fclose(infile);
+
+ if (!image_data) {
+ fprintf(stderr, PROGNAME ": unable to decode PNG image\n");
+ exit(3);
+ }
+
+
+ /* display image (composite with background if requested) */
+
+ Trace((stderr, "calling rpng_x_display_image()\n"))
+ if (rpng_x_display_image()) {
+ free(image_data);
+ exit(4);
+ }
+ Trace((stderr, "done with rpng_x_display_image()\n"))
+
+
+ /* wait for the user to tell us when to quit */
+
+ printf(
+ "Done. Press Q, Esc or mouse button 1 (within image window) to quit.\n");
+ fflush(stdout);
+
+ do
+ XNextEvent(display, &e);
+ while (!(e.type == ButtonPress && e.xbutton.button == Button1) &&
+ !(e.type == KeyPress && /* v--- or 1 for shifted keys */
+ ((k = XLookupKeysym(&e.xkey, 0)) == XK_q || k == XK_Escape) ));
+
+
+ /* OK, we're done: clean up all image and X resources and go away */
+
+ rpng_x_cleanup();
+
+ (void)argc; /* Unused */
+
+ return 0;
+}
+
+
+
+
+
+static int rpng_x_create_window(void)
+{
+ uch *xdata;
+ int need_colormap = FALSE;
+ int screen, pad;
+ ulg bg_pixel = 0L;
+ ulg attrmask;
+ Window root;
+ XEvent e;
+ XGCValues gcvalues;
+ XSetWindowAttributes attr;
+ XTextProperty windowName, *pWindowName = &windowName;
+ XTextProperty iconName, *pIconName = &iconName;
+ XVisualInfo visual_info;
+ XSizeHints *size_hints;
+ XWMHints *wm_hints;
+ XClassHint *class_hints;
+
+
+ screen = DefaultScreen(display);
+ depth = DisplayPlanes(display, screen);
+ root = RootWindow(display, screen);
+
+#ifdef DEBUG
+ XSynchronize(display, True);
+#endif
+
+#if 0
+/* GRR: add 8-bit support */
+ if (/* depth != 8 && */ depth != 16 && depth != 24 && depth != 32) {
+ fprintf(stderr,
+ "screen depth %d not supported (only 16-, 24- or 32-bit TrueColor)\n",
+ depth);
+ return 2;
+ }
+
+ XMatchVisualInfo(display, screen, depth,
+ (depth == 8)? PseudoColor : TrueColor, &visual_info);
+ visual = visual_info.visual;
+#else
+ if (depth != 16 && depth != 24 && depth != 32) {
+ int visuals_matched = 0;
+
+ Trace((stderr, "default depth is %d: checking other visuals\n",
+ depth))
+
+ /* 24-bit first */
+ visual_info.screen = screen;
+ visual_info.depth = 24;
+ visual_list = XGetVisualInfo(display,
+ VisualScreenMask | VisualDepthMask, &visual_info, &visuals_matched);
+ if (visuals_matched == 0) {
+/* GRR: add 15-, 16- and 32-bit TrueColor visuals (also DirectColor?) */
+ fprintf(stderr, "default screen depth %d not supported, and no"
+ " 24-bit visuals found\n", depth);
+ return 2;
+ }
+ Trace((stderr, "XGetVisualInfo() returned %d 24-bit visuals\n",
+ visuals_matched))
+ visual = visual_list[0].visual;
+ depth = visual_list[0].depth;
+/*
+ colormap_size = visual_list[0].colormap_size;
+ visual_class = visual->class;
+ visualID = XVisualIDFromVisual(visual);
+ */
+ have_nondefault_visual = TRUE;
+ need_colormap = TRUE;
+ } else {
+ XMatchVisualInfo(display, screen, depth, TrueColor, &visual_info);
+ visual = visual_info.visual;
+ }
+#endif
+
+ RMask = visual->red_mask;
+ GMask = visual->green_mask;
+ BMask = visual->blue_mask;
+
+/* GRR: add/check 8-bit support */
+ if (depth == 8 || need_colormap) {
+ colormap = XCreateColormap(display, root, visual, AllocNone);
+ if (!colormap) {
+ fprintf(stderr, "XCreateColormap() failed\n");
+ return 2;
+ }
+ have_colormap = TRUE;
+ }
+ if (depth == 15 || depth == 16) {
+ RShift = 15 - rpng_x_msb(RMask); /* these are right-shifts */
+ GShift = 15 - rpng_x_msb(GMask);
+ BShift = 15 - rpng_x_msb(BMask);
+ } else if (depth > 16) {
+#define NO_24BIT_MASKS
+#ifdef NO_24BIT_MASKS
+ RShift = rpng_x_msb(RMask) - 7; /* these are left-shifts */
+ GShift = rpng_x_msb(GMask) - 7;
+ BShift = rpng_x_msb(BMask) - 7;
+#else
+ RShift = 7 - rpng_x_msb(RMask); /* these are right-shifts, too */
+ GShift = 7 - rpng_x_msb(GMask);
+ BShift = 7 - rpng_x_msb(BMask);
+#endif
+ }
+ if (depth >= 15 && (RShift < 0 || GShift < 0 || BShift < 0)) {
+ fprintf(stderr, "rpng internal logic error: negative X shift(s)!\n");
+ return 2;
+ }
+
+/*---------------------------------------------------------------------------
+ Finally, create the window.
+ ---------------------------------------------------------------------------*/
+
+ attr.backing_store = Always;
+ attr.event_mask = ExposureMask | KeyPressMask | ButtonPressMask;
+ attrmask = CWBackingStore | CWEventMask;
+ if (have_nondefault_visual) {
+ attr.colormap = colormap;
+ attr.background_pixel = 0;
+ attr.border_pixel = 1;
+ attrmask |= CWColormap | CWBackPixel | CWBorderPixel;
+ }
+
+ window = XCreateWindow(display, root, 0, 0, image_width, image_height, 0,
+ depth, InputOutput, visual, attrmask, &attr);
+
+ if (window == None) {
+ fprintf(stderr, "XCreateWindow() failed\n");
+ return 2;
+ } else
+ have_window = TRUE;
+
+ if (depth == 8)
+ XSetWindowColormap(display, window, colormap);
+
+ if (!XStringListToTextProperty(&window_name, 1, pWindowName))
+ pWindowName = NULL;
+ if (!XStringListToTextProperty(&icon_name, 1, pIconName))
+ pIconName = NULL;
+
+ /* OK if any hints allocation fails; XSetWMProperties() allows NULLs */
+
+ if ((size_hints = XAllocSizeHints()) != NULL) {
+ /* window will not be resizable */
+ size_hints->flags = PMinSize | PMaxSize;
+ size_hints->min_width = size_hints->max_width = (int)image_width;
+ size_hints->min_height = size_hints->max_height = (int)image_height;
+ }
+
+ if ((wm_hints = XAllocWMHints()) != NULL) {
+ wm_hints->initial_state = NormalState;
+ wm_hints->input = True;
+ /* wm_hints->icon_pixmap = icon_pixmap; */
+ wm_hints->flags = StateHint | InputHint /* | IconPixmapHint */ ;
+ }
+
+ if ((class_hints = XAllocClassHint()) != NULL) {
+ class_hints->res_name = res_name;
+ class_hints->res_class = res_class;
+ }
+
+ XSetWMProperties(display, window, pWindowName, pIconName, NULL, 0,
+ size_hints, wm_hints, class_hints);
+
+ /* various properties and hints no longer needed; free memory */
+ if (pWindowName)
+ XFree(pWindowName->value);
+ if (pIconName)
+ XFree(pIconName->value);
+ if (size_hints)
+ XFree(size_hints);
+ if (wm_hints)
+ XFree(wm_hints);
+ if (class_hints)
+ XFree(class_hints);
+
+ XMapWindow(display, window);
+
+ gc = XCreateGC(display, window, 0, &gcvalues);
+ have_gc = TRUE;
+
+/*---------------------------------------------------------------------------
+ Fill window with the specified background color.
+ ---------------------------------------------------------------------------*/
+
+ if (depth == 24 || depth == 32) {
+ bg_pixel = ((ulg)bg_red << RShift) |
+ ((ulg)bg_green << GShift) |
+ ((ulg)bg_blue << BShift);
+ } else if (depth == 16) {
+ bg_pixel = ((((ulg)bg_red << 8) >> RShift) & RMask) |
+ ((((ulg)bg_green << 8) >> GShift) & GMask) |
+ ((((ulg)bg_blue << 8) >> BShift) & BMask);
+ } else /* depth == 8 */ {
+
+ /* GRR: add 8-bit support */
+
+ }
+
+ XSetForeground(display, gc, bg_pixel);
+ XFillRectangle(display, window, gc, 0, 0, image_width, image_height);
+
+/*---------------------------------------------------------------------------
+ Wait for first Expose event to do any drawing, then flush.
+ ---------------------------------------------------------------------------*/
+
+ do
+ XNextEvent(display, &e);
+ while (e.type != Expose || e.xexpose.count);
+
+ XFlush(display);
+
+/*---------------------------------------------------------------------------
+ Allocate memory for the X- and display-specific version of the image.
+ ---------------------------------------------------------------------------*/
+
+ if (depth == 24 || depth == 32) {
+ xdata = (uch *)malloc(4*image_width*image_height);
+ pad = 32;
+ } else if (depth == 16) {
+ xdata = (uch *)malloc(2*image_width*image_height);
+ pad = 16;
+ } else /* depth == 8 */ {
+ xdata = (uch *)malloc(image_width*image_height);
+ pad = 8;
+ }
+
+ if (!xdata) {
+ fprintf(stderr, PROGNAME ": unable to allocate image memory\n");
+ return 4;
+ }
+
+ ximage = XCreateImage(display, visual, depth, ZPixmap, 0,
+ (char *)xdata, image_width, image_height, pad, 0);
+
+ if (!ximage) {
+ fprintf(stderr, PROGNAME ": XCreateImage() failed\n");
+ free(xdata);
+ return 3;
+ }
+
+ /* to avoid testing the byte order every pixel (or doubling the size of
+ * the drawing routine with a giant if-test), we arbitrarily set the byte
+ * order to MSBFirst and let Xlib worry about inverting things on little-
+ * endian machines (like Linux/x86, old VAXen, etc.)--this is not the most
+ * efficient approach (the giant if-test would be better), but in the
+ * interest of clarity, we take the easy way out... */
+
+ ximage->byte_order = MSBFirst;
+
+ return 0;
+
+} /* end function rpng_x_create_window() */
+
+
+
+
+
+static int rpng_x_display_image(void)
+{
+ uch *src;
+ char *dest;
+ uch r, g, b, a;
+ ulg i, row, lastrow = 0;
+ ulg pixel;
+ int ximage_rowbytes = ximage->bytes_per_line;
+/* int bpp = ximage->bits_per_pixel; */
+
+
+ Trace((stderr, "beginning display loop (image_channels == %d)\n",
+ image_channels))
+ Trace((stderr, " (width = %ld, rowbytes = %ld, ximage_rowbytes = %d)\n",
+ image_width, image_rowbytes, ximage_rowbytes))
+ Trace((stderr, " (bpp = %d)\n", ximage->bits_per_pixel))
+ Trace((stderr, " (byte_order = %s)\n", ximage->byte_order == MSBFirst?
+ "MSBFirst" : (ximage->byte_order == LSBFirst? "LSBFirst" : "unknown")))
+
+ if (depth == 24 || depth == 32) {
+ ulg red, green, blue;
+
+ for (lastrow = row = 0; row < image_height; ++row) {
+ src = image_data + row*image_rowbytes;
+ dest = ximage->data + row*ximage_rowbytes;
+ if (image_channels == 3) {
+ for (i = image_width; i > 0; --i) {
+ red = *src++;
+ green = *src++;
+ blue = *src++;
+#ifdef NO_24BIT_MASKS
+ pixel = (red << RShift) |
+ (green << GShift) |
+ (blue << BShift);
+ /* recall that we set ximage->byte_order = MSBFirst above */
+ /* GRR BUG: this assumes bpp == 32, but may be 24: */
+ *dest++ = (char)((pixel >> 24) & 0xff);
+ *dest++ = (char)((pixel >> 16) & 0xff);
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+#else
+ red = (RShift < 0)? red << (-RShift) : red >> RShift;
+ green = (GShift < 0)? green << (-GShift) : green >> GShift;
+ blue = (BShift < 0)? blue << (-BShift) : blue >> BShift;
+ pixel = (red & RMask) | (green & GMask) | (blue & BMask);
+ /* recall that we set ximage->byte_order = MSBFirst above */
+ *dest++ = (char)((pixel >> 24) & 0xff);
+ *dest++ = (char)((pixel >> 16) & 0xff);
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+#endif
+ }
+ } else /* if (image_channels == 4) */ {
+ for (i = image_width; i > 0; --i) {
+ r = *src++;
+ g = *src++;
+ b = *src++;
+ a = *src++;
+ if (a == 255) {
+ red = r;
+ green = g;
+ blue = b;
+ } else if (a == 0) {
+ red = bg_red;
+ green = bg_green;
+ blue = bg_blue;
+ } else {
+ /* this macro (from png.h) composites the foreground
+ * and background values and puts the result into the
+ * first argument */
+ alpha_composite(red, r, a, bg_red);
+ alpha_composite(green, g, a, bg_green);
+ alpha_composite(blue, b, a, bg_blue);
+ }
+ pixel = (red << RShift) |
+ (green << GShift) |
+ (blue << BShift);
+ /* recall that we set ximage->byte_order = MSBFirst above */
+ *dest++ = (char)((pixel >> 24) & 0xff);
+ *dest++ = (char)((pixel >> 16) & 0xff);
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ }
+ }
+ /* display after every 16 lines */
+ if (((row+1) & 0xf) == 0) {
+ XPutImage(display, window, gc, ximage, 0, (int)lastrow, 0,
+ (int)lastrow, image_width, 16);
+ XFlush(display);
+ lastrow = row + 1;
+ }
+ }
+
+ } else if (depth == 16) {
+ ush red, green, blue;
+
+ for (lastrow = row = 0; row < image_height; ++row) {
+ src = image_data + row*image_rowbytes;
+ dest = ximage->data + row*ximage_rowbytes;
+ if (image_channels == 3) {
+ for (i = image_width; i > 0; --i) {
+ red = ((ush)(*src) << 8);
+ ++src;
+ green = ((ush)(*src) << 8);
+ ++src;
+ blue = ((ush)(*src) << 8);
+ ++src;
+ pixel = ((red >> RShift) & RMask) |
+ ((green >> GShift) & GMask) |
+ ((blue >> BShift) & BMask);
+ /* recall that we set ximage->byte_order = MSBFirst above */
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ }
+ } else /* if (image_channels == 4) */ {
+ for (i = image_width; i > 0; --i) {
+ r = *src++;
+ g = *src++;
+ b = *src++;
+ a = *src++;
+ if (a == 255) {
+ red = ((ush)r << 8);
+ green = ((ush)g << 8);
+ blue = ((ush)b << 8);
+ } else if (a == 0) {
+ red = ((ush)bg_red << 8);
+ green = ((ush)bg_green << 8);
+ blue = ((ush)bg_blue << 8);
+ } else {
+ /* this macro (from png.h) composites the foreground
+ * and background values and puts the result back into
+ * the first argument (== fg byte here: safe) */
+ alpha_composite(r, r, a, bg_red);
+ alpha_composite(g, g, a, bg_green);
+ alpha_composite(b, b, a, bg_blue);
+ red = ((ush)r << 8);
+ green = ((ush)g << 8);
+ blue = ((ush)b << 8);
+ }
+ pixel = ((red >> RShift) & RMask) |
+ ((green >> GShift) & GMask) |
+ ((blue >> BShift) & BMask);
+ /* recall that we set ximage->byte_order = MSBFirst above */
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ }
+ }
+ /* display after every 16 lines */
+ if (((row+1) & 0xf) == 0) {
+ XPutImage(display, window, gc, ximage, 0, (int)lastrow, 0,
+ (int)lastrow, image_width, 16);
+ XFlush(display);
+ lastrow = row + 1;
+ }
+ }
+
+ } else /* depth == 8 */ {
+
+ /* GRR: add 8-bit support */
+
+ }
+
+ Trace((stderr, "calling final XPutImage()\n"))
+ if (lastrow < image_height) {
+ XPutImage(display, window, gc, ximage, 0, (int)lastrow, 0,
+ (int)lastrow, image_width, image_height-lastrow);
+ XFlush(display);
+ }
+
+ return 0;
+}
+
+
+
+
+static void rpng_x_cleanup(void)
+{
+ if (image_data) {
+ free(image_data);
+ image_data = NULL;
+ }
+
+ if (ximage) {
+ if (ximage->data) {
+ free(ximage->data); /* we allocated it, so we free it */
+ ximage->data = (char *)NULL; /* instead of XDestroyImage() */
+ }
+ XDestroyImage(ximage);
+ ximage = NULL;
+ }
+
+ if (have_gc)
+ XFreeGC(display, gc);
+
+ if (have_window)
+ XDestroyWindow(display, window);
+
+ if (have_colormap)
+ XFreeColormap(display, colormap);
+
+ if (have_nondefault_visual)
+ XFree(visual_list);
+}
+
+
+
+
+
+static int rpng_x_msb(ulg u32val)
+{
+ int i;
+
+ for (i = 31; i >= 0; --i) {
+ if (u32val & 0x80000000L)
+ break;
+ u32val <<= 1;
+ }
+ return i;
+}
diff --git a/libpng/contrib/gregbook/rpng2-win.c b/libpng/contrib/gregbook/rpng2-win.c
new file mode 100644
index 0000000..a7b9dfa
--- /dev/null
+++ b/libpng/contrib/gregbook/rpng2-win.c
@@ -0,0 +1,1255 @@
+/*---------------------------------------------------------------------------
+
+ rpng2 - progressive-model PNG display program rpng2-win.c
+
+ This program decodes and displays PNG files progressively, as if it were
+ a web browser (though the front end is only set up to read from files).
+ It supports gamma correction, user-specified background colors, and user-
+ specified background patterns (for transparent images). This version is
+ for 32-bit Windows; it may compile under 16-bit Windows with a little
+ tweaking (or maybe not). Thanks to Adam Costello and Pieter S. van der
+ Meulen for the "diamond" and "radial waves" patterns, respectively.
+
+ to do (someday, maybe):
+ - handle quoted command-line args (especially filenames with spaces)
+ - finish resizable checkerboard-gradient (sizes 4-128?)
+ - use %.1023s to simplify truncation of title-bar string?
+ - have minimum window width: oh well
+
+ ---------------------------------------------------------------------------
+
+ Changelog:
+ - 1.01: initial public release
+ - 1.02: fixed cut-and-paste error in usage screen (oops...)
+ - 1.03: modified to allow abbreviated options
+ - 1.04: removed bogus extra argument from usage fprintf() [Glenn R-P?];
+ fixed command-line parsing bug
+ - 1.10: enabled "message window"/console (thanks to David Geldreich)
+ - 1.20: added runtime MMX-enabling/disabling and new -mmx* options
+ - 1.21: made minor tweak to usage screen to fit within 25-line console
+ - 1.22: added AMD64/EM64T support (__x86_64__)
+ - 2.00: dual-licensed (added GNU GPL)
+ - 2.01: fixed 64-bit typo in readpng2.c
+ - 2.02: fixed improper display of usage screen on PNG error(s); fixed
+ unexpected-EOF and file-read-error cases
+ - 2.03: removed runtime MMX-enabling/disabling and obsolete -mmx* options
+ - 2.04:
+ (GR-P)
+
+ ---------------------------------------------------------------------------
+
+ Copyright (c) 1998-2008 Greg Roelofs. All rights reserved.
+
+ This software is provided "as is," without warranty of any kind,
+ express or implied. In no event shall the author or contributors
+ be held liable for any damages arising in any way from the use of
+ this software.
+
+ The contents of this file are DUAL-LICENSED. You may modify and/or
+ redistribute this software according to the terms of one of the
+ following two licenses (at your option):
+
+
+ LICENSE 1 ("BSD-like with advertising clause"):
+
+ Permission is granted to anyone to use this software for any purpose,
+ including commercial applications, and to alter it and redistribute
+ it freely, subject to the following restrictions:
+
+ 1. Redistributions of source code must retain the above copyright
+ notice, disclaimer, and this list of conditions.
+ 2. Redistributions in binary form must reproduce the above copyright
+ notice, disclaimer, and this list of conditions in the documenta-
+ tion and/or other materials provided with the distribution.
+ 3. All advertising materials mentioning features or use of this
+ software must display the following acknowledgment:
+
+ This product includes software developed by Greg Roelofs
+ and contributors for the book, "PNG: The Definitive Guide,"
+ published by O'Reilly and Associates.
+
+
+ LICENSE 2 (GNU GPL v2 or later):
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ ---------------------------------------------------------------------------*/
+
+#define PROGNAME "rpng2-win"
+#define LONGNAME "Progressive PNG Viewer for Windows"
+#define VERSION "2.02 of 16 March 2008"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <setjmp.h> /* for jmpbuf declaration in readpng2.h */
+#include <time.h>
+#include <math.h> /* only for PvdM background code */
+#include <windows.h>
+#ifdef __CYGWIN__
+/* getch replacement. Turns out, we don't really need this,
+ * but leave it here if we ever enable any of the uses of
+ * _getch in the main code
+ */
+#include <unistd.h>
+#include <termio.h>
+#include <sys/ioctl.h>
+int repl_getch( void )
+{
+ char ch;
+ int fd = fileno(stdin);
+ struct termio old_tty, new_tty;
+
+ ioctl(fd, TCGETA, &old_tty);
+ new_tty = old_tty;
+ new_tty.c_lflag &= ~(ICANON | ECHO | ISIG);
+ ioctl(fd, TCSETA, &new_tty);
+ fread(&ch, 1, sizeof(ch), stdin);
+ ioctl(fd, TCSETA, &old_tty);
+
+ return ch;
+}
+#define _getch repl_getch
+#else
+#include <conio.h> /* only for _getch() */
+#endif
+
+/* all for PvdM background code: */
+#ifndef PI
+# define PI 3.141592653589793238
+#endif
+#define PI_2 (PI*0.5)
+#define INV_PI_360 (360.0 / PI)
+#define MAX(a,b) (a>b?a:b)
+#define MIN(a,b) (a<b?a:b)
+#define CLIP(a,min,max) MAX(min,MIN((a),max))
+#define ABS(a) ((a)<0?-(a):(a))
+#define CLIP8P(c) MAX(0,(MIN((c),255))) /* 8-bit pos. integer (uch) */
+#define ROUNDF(f) ((int)(f + 0.5))
+
+#define rgb1_max bg_freq
+#define rgb1_min bg_gray
+#define rgb2_max bg_bsat
+#define rgb2_min bg_brot
+
+/* #define DEBUG */ /* this enables the Trace() macros */
+
+#include "readpng2.h" /* typedefs, common macros, readpng2 prototypes */
+
+
+/* could just include png.h, but this macro is the only thing we need
+ * (name and typedefs changed to local versions); note that side effects
+ * only happen with alpha (which could easily be avoided with
+ * "ush acopy = (alpha);") */
+
+#define alpha_composite(composite, fg, alpha, bg) { \
+ ush temp = ((ush)(fg)*(ush)(alpha) + \
+ (ush)(bg)*(ush)(255 - (ush)(alpha)) + (ush)128); \
+ (composite) = (uch)((temp + (temp >> 8)) >> 8); \
+}
+
+
+#define INBUFSIZE 4096 /* with pseudo-timing on (1 sec delay/block), this
+ * block size corresponds roughly to a download
+ * speed 10% faster than theoretical 33.6K maximum
+ * (assuming 8 data bits, 1 stop bit and no other
+ * overhead) */
+
+/* local prototypes */
+static void rpng2_win_init(void);
+static int rpng2_win_create_window(void);
+static int rpng2_win_load_bg_image(void);
+static void rpng2_win_display_row(ulg row);
+static void rpng2_win_finish_display(void);
+static void rpng2_win_cleanup(void);
+LRESULT CALLBACK rpng2_win_wndproc(HWND, UINT, WPARAM, LPARAM);
+
+
+static char titlebar[1024];
+static char *progname = PROGNAME;
+static char *appname = LONGNAME;
+static char *filename;
+static FILE *infile;
+
+static mainprog_info rpng2_info;
+
+static uch inbuf[INBUFSIZE];
+static int incount;
+
+static int pat = 6; /* must be less than num_bgpat */
+static int bg_image = 0;
+static int bgscale = 16;
+static ulg bg_rowbytes;
+static uch *bg_data;
+
+static struct rgb_color {
+ uch r, g, b;
+} rgb[] = {
+ { 0, 0, 0}, /* 0: black */
+ {255, 255, 255}, /* 1: white */
+ {173, 132, 57}, /* 2: tan */
+ { 64, 132, 0}, /* 3: medium green */
+ {189, 117, 1}, /* 4: gold */
+ {253, 249, 1}, /* 5: yellow */
+ { 0, 0, 255}, /* 6: blue */
+ { 0, 0, 120}, /* 7: medium blue */
+ {255, 0, 255}, /* 8: magenta */
+ { 64, 0, 64}, /* 9: dark magenta */
+ {255, 0, 0}, /* 10: red */
+ { 64, 0, 0}, /* 11: dark red */
+ {255, 127, 0}, /* 12: orange */
+ {192, 96, 0}, /* 13: darker orange */
+ { 24, 60, 0}, /* 14: dark green-yellow */
+ { 85, 125, 200} /* 15: ice blue */
+};
+/* not used for now, but should be for error-checking:
+static int num_rgb = sizeof(rgb) / sizeof(struct rgb_color);
+ */
+
+/*
+ This whole struct is a fairly cheesy way to keep the number of
+ command-line options to a minimum. The radial-waves background
+ type is a particularly poor fit to the integer elements of the
+ struct...but a few macros and a little fixed-point math will do
+ wonders for ya.
+
+ type bits:
+ F E D C B A 9 8 7 6 5 4 3 2 1 0
+ | | | | |
+ | | +-+-+-- 0 = sharp-edged checkerboard
+ | | 1 = soft diamonds
+ | | 2 = radial waves
+ | | 3-7 = undefined
+ | +-- gradient #2 inverted?
+ +-- alternating columns inverted?
+ */
+static struct background_pattern {
+ ush type;
+ int rgb1_max, rgb1_min; /* or bg_freq, bg_gray */
+ int rgb2_max, rgb2_min; /* or bg_bsat, bg_brot (both scaled by 10)*/
+} bg[] = {
+ {0+8, 2,0, 1,15}, /* checkered: tan/black vs. white/ice blue */
+ {0+24, 2,0, 1,0}, /* checkered: tan/black vs. white/black */
+ {0+8, 4,5, 0,2}, /* checkered: gold/yellow vs. black/tan */
+ {0+8, 4,5, 0,6}, /* checkered: gold/yellow vs. black/blue */
+ {0, 7,0, 8,9}, /* checkered: deep blue/black vs. magenta */
+ {0+8, 13,0, 5,14}, /* checkered: orange/black vs. yellow */
+ {0+8, 12,0, 10,11}, /* checkered: orange/black vs. red */
+ {1, 7,0, 8,0}, /* diamonds: deep blue/black vs. magenta */
+ {1, 12,0, 11,0}, /* diamonds: orange vs. dark red */
+ {1, 10,0, 7,0}, /* diamonds: red vs. medium blue */
+ {1, 4,0, 5,0}, /* diamonds: gold vs. yellow */
+ {1, 3,0, 0,0}, /* diamonds: medium green vs. black */
+ {2, 16, 100, 20, 0}, /* radial: ~hard radial color-beams */
+ {2, 18, 100, 10, 2}, /* radial: soft, curved radial color-beams */
+ {2, 16, 256, 100, 250}, /* radial: very tight spiral */
+ {2, 10000, 256, 11, 0} /* radial: dipole-moire' (almost fractal) */
+};
+static int num_bgpat = sizeof(bg) / sizeof(struct background_pattern);
+
+
+/* Windows-specific global variables (could go in struct, but messy...) */
+static ulg wimage_rowbytes;
+static uch *dib;
+static uch *wimage_data;
+static BITMAPINFOHEADER *bmih;
+
+static HWND global_hwnd;
+static HINSTANCE global_hInst;
+static int global_showmode;
+
+
+
+
+int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrevInst, PSTR cmd, int showmode)
+{
+ char *args[1024]; /* arbitrary limit, but should suffice */
+ char **argv = args;
+ char *p, *q, *bgstr = NULL;
+ int argc = 0;
+ int rc, alen, flen;
+ int error = 0;
+ int timing = FALSE;
+ int have_bg = FALSE;
+ double LUT_exponent; /* just the lookup table */
+ double CRT_exponent = 2.2; /* just the monitor */
+ double default_display_exponent; /* whole display system */
+ MSG msg;
+
+
+ /* First initialize a few things, just to be sure--memset takes care of
+ * default background color (black), booleans (FALSE), pointers (NULL),
+ * etc. */
+
+ global_hInst = hInst;
+ global_showmode = showmode;
+ filename = (char *)NULL;
+ memset(&rpng2_info, 0, sizeof(mainprog_info));
+
+#ifndef __CYGWIN__
+ /* Next reenable console output, which normally goes to the bit bucket
+ * for windowed apps. Closing the console window will terminate the
+ * app. Thanks to David.Geldreich@realviz.com for supplying the magical
+ * incantation. */
+
+ AllocConsole();
+ freopen("CONOUT$", "a", stderr);
+ freopen("CONOUT$", "a", stdout);
+#endif
+
+ /* Set the default value for our display-system exponent, i.e., the
+ * product of the CRT exponent and the exponent corresponding to
+ * the frame-buffer's lookup table (LUT), if any. This is not an
+ * exhaustive list of LUT values (e.g., OpenStep has a lot of weird
+ * ones), but it should cover 99% of the current possibilities. And
+ * yes, these ifdefs are completely wasted in a Windows program... */
+
+#if defined(NeXT)
+ /* third-party utilities can modify the default LUT exponent */
+ LUT_exponent = 1.0 / 2.2;
+ /*
+ if (some_next_function_that_returns_gamma(&next_gamma))
+ LUT_exponent = 1.0 / next_gamma;
+ */
+#elif defined(sgi)
+ LUT_exponent = 1.0 / 1.7;
+ /* there doesn't seem to be any documented function to
+ * get the "gamma" value, so we do it the hard way */
+ infile = fopen("/etc/config/system.glGammaVal", "r");
+ if (infile) {
+ double sgi_gamma;
+
+ fgets(tmpline, 80, infile);
+ fclose(infile);
+ sgi_gamma = atof(tmpline);
+ if (sgi_gamma > 0.0)
+ LUT_exponent = 1.0 / sgi_gamma;
+ }
+#elif defined(Macintosh)
+ LUT_exponent = 1.8 / 2.61;
+ /*
+ if (some_mac_function_that_returns_gamma(&mac_gamma))
+ LUT_exponent = mac_gamma / 2.61;
+ */
+#else
+ LUT_exponent = 1.0; /* assume no LUT: most PCs */
+#endif
+
+ /* the defaults above give 1.0, 1.3, 1.5 and 2.2, respectively: */
+ default_display_exponent = LUT_exponent * CRT_exponent;
+
+
+ /* If the user has set the SCREEN_GAMMA environment variable as suggested
+ * (somewhat imprecisely) in the libpng documentation, use that; otherwise
+ * use the default value we just calculated. Either way, the user may
+ * override this via a command-line option. */
+
+ if ((p = getenv("SCREEN_GAMMA")) != NULL)
+ rpng2_info.display_exponent = atof(p);
+ else
+ rpng2_info.display_exponent = default_display_exponent;
+
+
+ /* Windows really hates command lines, so we have to set up our own argv.
+ * Note that we do NOT bother with quoted arguments here, so don't use
+ * filenames with spaces in 'em! */
+
+ argv[argc++] = PROGNAME;
+ p = cmd;
+ for (;;) {
+ if (*p == ' ')
+ while (*++p == ' ')
+ ;
+ /* now p points at the first non-space after some spaces */
+ if (*p == '\0')
+ break; /* nothing after the spaces: done */
+ argv[argc++] = q = p;
+ while (*q && *q != ' ')
+ ++q;
+ /* now q points at a space or the end of the string */
+ if (*q == '\0')
+ break; /* last argv already terminated; quit */
+ *q = '\0'; /* change space to terminator */
+ p = q + 1;
+ }
+ argv[argc] = NULL; /* terminate the argv array itself */
+
+
+ /* Now parse the command line for options and the PNG filename. */
+
+ while (*++argv && !error) {
+ if (!strncmp(*argv, "-gamma", 2)) {
+ if (!*++argv)
+ ++error;
+ else {
+ rpng2_info.display_exponent = atof(*argv);
+ if (rpng2_info.display_exponent <= 0.0)
+ ++error;
+ }
+ } else if (!strncmp(*argv, "-bgcolor", 4)) {
+ if (!*++argv)
+ ++error;
+ else {
+ bgstr = *argv;
+ if (strlen(bgstr) != 7 || bgstr[0] != '#')
+ ++error;
+ else {
+ have_bg = TRUE;
+ bg_image = FALSE;
+ }
+ }
+ } else if (!strncmp(*argv, "-bgpat", 4)) {
+ if (!*++argv)
+ ++error;
+ else {
+ pat = atoi(*argv) - 1;
+ if (pat < 0 || pat >= num_bgpat)
+ ++error;
+ else {
+ bg_image = TRUE;
+ have_bg = FALSE;
+ }
+ }
+ } else if (!strncmp(*argv, "-timing", 2)) {
+ timing = TRUE;
+ } else {
+ if (**argv != '-') {
+ filename = *argv;
+ if (argv[1]) /* shouldn't be any more args after filename */
+ ++error;
+ } else
+ ++error; /* not expecting any other options */
+ }
+ }
+
+ if (!filename)
+ ++error;
+
+
+ /* print usage screen if any errors up to this point */
+
+ if (error) {
+#ifndef __CYGWIN__
+ int ch;
+#endif
+
+ fprintf(stderr, "\n%s %s: %s\n\n", PROGNAME, VERSION, appname);
+ readpng2_version_info();
+ fprintf(stderr, "\n"
+ "Usage: %s [-gamma exp] [-bgcolor bg | -bgpat pat] [-timing]\n"
+ " %*s file.png\n\n"
+ " exp \ttransfer-function exponent (``gamma'') of the display\n"
+ "\t\t system in floating-point format (e.g., ``%.1f''); equal\n"
+ "\t\t to the product of the lookup-table exponent (varies)\n"
+ "\t\t and the CRT exponent (usually 2.2); must be positive\n"
+ " bg \tdesired background color in 7-character hex RGB format\n"
+ "\t\t (e.g., ``#ff7700'' for orange: same as HTML colors);\n"
+ "\t\t used with transparent images; overrides -bgpat option\n"
+ " pat \tdesired background pattern number (1-%d); used with\n"
+ "\t\t transparent images; overrides -bgcolor option\n"
+ " -timing\tenables delay for every block read, to simulate modem\n"
+ "\t\t download of image (~36 Kbps)\n"
+ "\nPress Q, Esc or mouse button 1 after image is displayed to quit.\n"
+#ifndef __CYGWIN__
+ "Press Q or Esc to quit this usage screen. ",
+#else
+ ,
+#endif
+ PROGNAME,
+#if (defined(__i386__) || defined(_M_IX86) || defined(__x86_64__)) && \
+ !(defined(__CYGWIN__) || defined(__MINGW32__))
+ (int)strlen(PROGNAME), " ",
+#endif
+ (int)strlen(PROGNAME), " ", default_display_exponent, num_bgpat);
+ fflush(stderr);
+#ifndef __CYGWIN__
+ do
+ ch = _getch();
+ while (ch != 'q' && ch != 'Q' && ch != 0x1B);
+#endif
+ exit(1);
+ }
+
+
+ if (!(infile = fopen(filename, "rb"))) {
+ fprintf(stderr, PROGNAME ": can't open PNG file [%s]\n", filename);
+ ++error;
+ } else {
+ incount = fread(inbuf, 1, INBUFSIZE, infile);
+ if (incount < 8 || !readpng2_check_sig(inbuf, 8)) {
+ fprintf(stderr, PROGNAME
+ ": [%s] is not a PNG file: incorrect signature\n",
+ filename);
+ ++error;
+ } else if ((rc = readpng2_init(&rpng2_info)) != 0) {
+ switch (rc) {
+ case 2:
+ fprintf(stderr, PROGNAME
+ ": [%s] has bad IHDR (libpng longjmp)\n", filename);
+ break;
+ case 4:
+ fprintf(stderr, PROGNAME ": insufficient memory\n");
+ break;
+ default:
+ fprintf(stderr, PROGNAME
+ ": unknown readpng2_init() error\n");
+ break;
+ }
+ ++error;
+ }
+ if (error)
+ fclose(infile);
+ }
+
+
+ if (error) {
+#ifndef __CYGWIN__
+ int ch;
+#endif
+
+ fprintf(stderr, PROGNAME ": aborting.\n");
+#ifndef __CYGWIN__
+ do
+ ch = _getch();
+ while (ch != 'q' && ch != 'Q' && ch != 0x1B);
+#endif
+ exit(2);
+ } else {
+ fprintf(stderr, "\n%s %s: %s\n", PROGNAME, VERSION, appname);
+#ifndef __CYGWIN__
+ fprintf(stderr,
+ "\n [console window: closing this window will terminate %s]\n\n",
+ PROGNAME);
+#endif
+ fflush(stderr);
+ }
+
+
+ /* set the title-bar string, but make sure buffer doesn't overflow */
+
+ alen = strlen(appname);
+ flen = strlen(filename);
+ if (alen + flen + 3 > 1023)
+ sprintf(titlebar, "%s: ...%s", appname, filename+(alen+flen+6-1023));
+ else
+ sprintf(titlebar, "%s: %s", appname, filename);
+
+
+ /* set some final rpng2_info variables before entering main data loop */
+
+ if (have_bg) {
+ unsigned r, g, b; /* this approach quiets compiler warnings */
+
+ sscanf(bgstr+1, "%2x%2x%2x", &r, &g, &b);
+ rpng2_info.bg_red = (uch)r;
+ rpng2_info.bg_green = (uch)g;
+ rpng2_info.bg_blue = (uch)b;
+ } else
+ rpng2_info.need_bgcolor = TRUE;
+
+ rpng2_info.state = kPreInit;
+ rpng2_info.mainprog_init = rpng2_win_init;
+ rpng2_info.mainprog_display_row = rpng2_win_display_row;
+ rpng2_info.mainprog_finish_display = rpng2_win_finish_display;
+
+
+ /* OK, this is the fun part: call readpng2_decode_data() at the start of
+ * the loop to deal with our first buffer of data (read in above to verify
+ * that the file is a PNG image), then loop through the file and continue
+ * calling the same routine to handle each chunk of data. It in turn
+ * passes the data to libpng, which will invoke one or more of our call-
+ * backs as decoded data become available. We optionally call Sleep() for
+ * one second per iteration to simulate downloading the image via an analog
+ * modem. */
+
+ for (;;) {
+ Trace((stderr, "about to call readpng2_decode_data()\n"))
+ if (readpng2_decode_data(&rpng2_info, inbuf, incount))
+ ++error;
+ Trace((stderr, "done with readpng2_decode_data()\n"))
+
+ if (error || incount != INBUFSIZE || rpng2_info.state == kDone) {
+ if (rpng2_info.state == kDone) {
+ Trace((stderr, "done decoding PNG image\n"))
+ } else if (ferror(infile)) {
+ fprintf(stderr, PROGNAME
+ ": error while reading PNG image file\n");
+ exit(3);
+ } else if (feof(infile)) {
+ fprintf(stderr, PROGNAME ": end of file reached "
+ "(unexpectedly) while reading PNG image file\n");
+ exit(3);
+ } else /* if (error) */ {
+ /* will print error message below */
+ }
+ break;
+ }
+
+ if (timing)
+ Sleep(1000L);
+
+ incount = fread(inbuf, 1, INBUFSIZE, infile);
+ }
+
+
+ /* clean up PNG stuff and report any decoding errors */
+
+ fclose(infile);
+ Trace((stderr, "about to call readpng2_cleanup()\n"))
+ readpng2_cleanup(&rpng2_info);
+
+ if (error) {
+ fprintf(stderr, PROGNAME ": libpng error while decoding PNG image\n");
+ exit(3);
+ }
+
+
+ /* wait for the user to tell us when to quit */
+
+ while (GetMessage(&msg, NULL, 0, 0)) {
+ TranslateMessage(&msg);
+ DispatchMessage(&msg);
+ }
+
+
+ /* we're done: clean up all image and Windows resources and go away */
+
+ Trace((stderr, "about to call rpng2_win_cleanup()\n"))
+ rpng2_win_cleanup();
+
+ return msg.wParam;
+}
+
+
+
+
+
+/* this function is called by readpng2_info_callback() in readpng2.c, which
+ * in turn is called by libpng after all of the pre-IDAT chunks have been
+ * read and processed--i.e., we now have enough info to finish initializing */
+
+static void rpng2_win_init()
+{
+ ulg i;
+ ulg rowbytes = rpng2_info.rowbytes;
+
+ Trace((stderr, "beginning rpng2_win_init()\n"))
+ Trace((stderr, " rowbytes = %d\n", rpng2_info.rowbytes))
+ Trace((stderr, " width = %ld\n", rpng2_info.width))
+ Trace((stderr, " height = %ld\n", rpng2_info.height))
+
+ rpng2_info.image_data = (uch *)malloc(rowbytes * rpng2_info.height);
+ if (!rpng2_info.image_data) {
+ readpng2_cleanup(&rpng2_info);
+ return;
+ }
+
+ rpng2_info.row_pointers = (uch **)malloc(rpng2_info.height * sizeof(uch *));
+ if (!rpng2_info.row_pointers) {
+ free(rpng2_info.image_data);
+ rpng2_info.image_data = NULL;
+ readpng2_cleanup(&rpng2_info);
+ return;
+ }
+
+ for (i = 0; i < rpng2_info.height; ++i)
+ rpng2_info.row_pointers[i] = rpng2_info.image_data + i*rowbytes;
+
+/*---------------------------------------------------------------------------
+ Do the basic Windows initialization stuff, make the window, and fill it
+ with the user-specified, file-specified or default background color.
+ ---------------------------------------------------------------------------*/
+
+ if (rpng2_win_create_window()) {
+ readpng2_cleanup(&rpng2_info);
+ return;
+ }
+
+ rpng2_info.state = kWindowInit;
+}
+
+
+
+
+
+static int rpng2_win_create_window()
+{
+ uch bg_red = rpng2_info.bg_red;
+ uch bg_green = rpng2_info.bg_green;
+ uch bg_blue = rpng2_info.bg_blue;
+ uch *dest;
+ int extra_width, extra_height;
+ ulg i, j;
+ WNDCLASSEX wndclass;
+ RECT rect;
+
+
+/*---------------------------------------------------------------------------
+ Allocate memory for the display-specific version of the image (round up
+ to multiple of 4 for Windows DIB).
+ ---------------------------------------------------------------------------*/
+
+ wimage_rowbytes = ((3*rpng2_info.width + 3L) >> 2) << 2;
+
+ if (!(dib = (uch *)malloc(sizeof(BITMAPINFOHEADER) +
+ wimage_rowbytes*rpng2_info.height)))
+ {
+ return 4; /* fail */
+ }
+
+/*---------------------------------------------------------------------------
+ Initialize the DIB. Negative height means to use top-down BMP ordering
+ (must be uncompressed, but that's what we want). Bit count of 1, 4 or 8
+ implies a colormap of RGBX quads, but 24-bit BMPs just use B,G,R values
+ directly => wimage_data begins immediately after BMP header.
+ ---------------------------------------------------------------------------*/
+
+ memset(dib, 0, sizeof(BITMAPINFOHEADER));
+ bmih = (BITMAPINFOHEADER *)dib;
+ bmih->biSize = sizeof(BITMAPINFOHEADER);
+ bmih->biWidth = rpng2_info.width;
+ bmih->biHeight = -((long)rpng2_info.height);
+ bmih->biPlanes = 1;
+ bmih->biBitCount = 24;
+ bmih->biCompression = 0;
+ wimage_data = dib + sizeof(BITMAPINFOHEADER);
+
+/*---------------------------------------------------------------------------
+ Fill window with the specified background color (default is black), but
+ defer loading faked "background image" until window is displayed (may be
+ slow to compute). Data are in BGR order.
+ ---------------------------------------------------------------------------*/
+
+ if (bg_image) { /* just fill with black for now */
+ memset(wimage_data, 0, wimage_rowbytes*rpng2_info.height);
+ } else {
+ for (j = 0; j < rpng2_info.height; ++j) {
+ dest = wimage_data + j*wimage_rowbytes;
+ for (i = rpng2_info.width; i > 0; --i) {
+ *dest++ = bg_blue;
+ *dest++ = bg_green;
+ *dest++ = bg_red;
+ }
+ }
+ }
+
+/*---------------------------------------------------------------------------
+ Set the window parameters.
+ ---------------------------------------------------------------------------*/
+
+ memset(&wndclass, 0, sizeof(wndclass));
+
+ wndclass.cbSize = sizeof(wndclass);
+ wndclass.style = CS_HREDRAW | CS_VREDRAW;
+ wndclass.lpfnWndProc = rpng2_win_wndproc;
+ wndclass.hInstance = global_hInst;
+ wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
+ wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);
+ wndclass.hbrBackground = (HBRUSH)GetStockObject(DKGRAY_BRUSH);
+ wndclass.lpszMenuName = NULL;
+ wndclass.lpszClassName = progname;
+ wndclass.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
+
+ RegisterClassEx(&wndclass);
+
+/*---------------------------------------------------------------------------
+ Finally, create the window.
+ ---------------------------------------------------------------------------*/
+
+ extra_width = 2*(GetSystemMetrics(SM_CXBORDER) +
+ GetSystemMetrics(SM_CXDLGFRAME));
+ extra_height = 2*(GetSystemMetrics(SM_CYBORDER) +
+ GetSystemMetrics(SM_CYDLGFRAME)) +
+ GetSystemMetrics(SM_CYCAPTION);
+
+ global_hwnd = CreateWindow(progname, titlebar, WS_OVERLAPPEDWINDOW,
+ CW_USEDEFAULT, CW_USEDEFAULT, rpng2_info.width+extra_width,
+ rpng2_info.height+extra_height, NULL, NULL, global_hInst, NULL);
+
+ ShowWindow(global_hwnd, global_showmode);
+ UpdateWindow(global_hwnd);
+
+/*---------------------------------------------------------------------------
+ Now compute the background image and display it. If it fails (memory
+ allocation), revert to a plain background color.
+ ---------------------------------------------------------------------------*/
+
+ if (bg_image) {
+ static const char *msg = "Computing background image...";
+ int x, y, len = strlen(msg);
+ HDC hdc = GetDC(global_hwnd);
+ TEXTMETRIC tm;
+
+ GetTextMetrics(hdc, &tm);
+ x = (rpng2_info.width - len*tm.tmAveCharWidth)/2;
+ y = (rpng2_info.height - tm.tmHeight)/2;
+ SetBkMode(hdc, TRANSPARENT);
+ SetTextColor(hdc, GetSysColor(COLOR_HIGHLIGHTTEXT));
+ /* this can still begin out of bounds even if x is positive (???): */
+ TextOut(hdc, ((x < 0)? 0 : x), ((y < 0)? 0 : y), msg, len);
+ ReleaseDC(global_hwnd, hdc);
+
+ rpng2_win_load_bg_image(); /* resets bg_image if fails */
+ }
+
+ if (!bg_image) {
+ for (j = 0; j < rpng2_info.height; ++j) {
+ dest = wimage_data + j*wimage_rowbytes;
+ for (i = rpng2_info.width; i > 0; --i) {
+ *dest++ = bg_blue;
+ *dest++ = bg_green;
+ *dest++ = bg_red;
+ }
+ }
+ }
+
+ rect.left = 0L;
+ rect.top = 0L;
+ rect.right = (LONG)rpng2_info.width; /* possibly off by one? */
+ rect.bottom = (LONG)rpng2_info.height; /* possibly off by one? */
+ InvalidateRect(global_hwnd, &rect, FALSE);
+ UpdateWindow(global_hwnd); /* similar to XFlush() */
+
+ return 0;
+
+} /* end function rpng2_win_create_window() */
+
+
+
+
+
+static int rpng2_win_load_bg_image()
+{
+ uch *src, *dest;
+ uch r1, r2, g1, g2, b1, b2;
+ uch r1_inv, r2_inv, g1_inv, g2_inv, b1_inv, b2_inv;
+ int k, hmax, max;
+ int xidx, yidx, yidx_max = (bgscale-1);
+ int even_odd_vert, even_odd_horiz, even_odd;
+ int invert_gradient2 = (bg[pat].type & 0x08);
+ int invert_column;
+ ulg i, row;
+
+/*---------------------------------------------------------------------------
+ Allocate buffer for fake background image to be used with transparent
+ images; if this fails, revert to plain background color.
+ ---------------------------------------------------------------------------*/
+
+ bg_rowbytes = 3 * rpng2_info.width;
+ bg_data = (uch *)malloc(bg_rowbytes * rpng2_info.height);
+ if (!bg_data) {
+ fprintf(stderr, PROGNAME
+ ": unable to allocate memory for background image\n");
+ bg_image = 0;
+ return 1;
+ }
+
+/*---------------------------------------------------------------------------
+ Vertical gradients (ramps) in NxN squares, alternating direction and
+ colors (N == bgscale).
+ ---------------------------------------------------------------------------*/
+
+ if ((bg[pat].type & 0x07) == 0) {
+ uch r1_min = rgb[bg[pat].rgb1_min].r;
+ uch g1_min = rgb[bg[pat].rgb1_min].g;
+ uch b1_min = rgb[bg[pat].rgb1_min].b;
+ uch r2_min = rgb[bg[pat].rgb2_min].r;
+ uch g2_min = rgb[bg[pat].rgb2_min].g;
+ uch b2_min = rgb[bg[pat].rgb2_min].b;
+ int r1_diff = rgb[bg[pat].rgb1_max].r - r1_min;
+ int g1_diff = rgb[bg[pat].rgb1_max].g - g1_min;
+ int b1_diff = rgb[bg[pat].rgb1_max].b - b1_min;
+ int r2_diff = rgb[bg[pat].rgb2_max].r - r2_min;
+ int g2_diff = rgb[bg[pat].rgb2_max].g - g2_min;
+ int b2_diff = rgb[bg[pat].rgb2_max].b - b2_min;
+
+ for (row = 0; row < rpng2_info.height; ++row) {
+ yidx = row % bgscale;
+ even_odd_vert = (row / bgscale) & 1;
+
+ r1 = r1_min + (r1_diff * yidx) / yidx_max;
+ g1 = g1_min + (g1_diff * yidx) / yidx_max;
+ b1 = b1_min + (b1_diff * yidx) / yidx_max;
+ r1_inv = r1_min + (r1_diff * (yidx_max-yidx)) / yidx_max;
+ g1_inv = g1_min + (g1_diff * (yidx_max-yidx)) / yidx_max;
+ b1_inv = b1_min + (b1_diff * (yidx_max-yidx)) / yidx_max;
+
+ r2 = r2_min + (r2_diff * yidx) / yidx_max;
+ g2 = g2_min + (g2_diff * yidx) / yidx_max;
+ b2 = b2_min + (b2_diff * yidx) / yidx_max;
+ r2_inv = r2_min + (r2_diff * (yidx_max-yidx)) / yidx_max;
+ g2_inv = g2_min + (g2_diff * (yidx_max-yidx)) / yidx_max;
+ b2_inv = b2_min + (b2_diff * (yidx_max-yidx)) / yidx_max;
+
+ dest = bg_data + row*bg_rowbytes;
+ for (i = 0; i < rpng2_info.width; ++i) {
+ even_odd_horiz = (i / bgscale) & 1;
+ even_odd = even_odd_vert ^ even_odd_horiz;
+ invert_column =
+ (even_odd_horiz && (bg[pat].type & 0x10));
+ if (even_odd == 0) { /* gradient #1 */
+ if (invert_column) {
+ *dest++ = r1_inv;
+ *dest++ = g1_inv;
+ *dest++ = b1_inv;
+ } else {
+ *dest++ = r1;
+ *dest++ = g1;
+ *dest++ = b1;
+ }
+ } else { /* gradient #2 */
+ if ((invert_column && invert_gradient2) ||
+ (!invert_column && !invert_gradient2))
+ {
+ *dest++ = r2; /* not inverted or */
+ *dest++ = g2; /* doubly inverted */
+ *dest++ = b2;
+ } else {
+ *dest++ = r2_inv;
+ *dest++ = g2_inv; /* singly inverted */
+ *dest++ = b2_inv;
+ }
+ }
+ }
+ }
+
+/*---------------------------------------------------------------------------
+ Soft gradient-diamonds with scale = bgscale. Code contributed by Adam
+ M. Costello.
+ ---------------------------------------------------------------------------*/
+
+ } else if ((bg[pat].type & 0x07) == 1) {
+
+ hmax = (bgscale-1)/2; /* half the max weight of a color */
+ max = 2*hmax; /* the max weight of a color */
+
+ r1 = rgb[bg[pat].rgb1_max].r;
+ g1 = rgb[bg[pat].rgb1_max].g;
+ b1 = rgb[bg[pat].rgb1_max].b;
+ r2 = rgb[bg[pat].rgb2_max].r;
+ g2 = rgb[bg[pat].rgb2_max].g;
+ b2 = rgb[bg[pat].rgb2_max].b;
+
+ for (row = 0; row < rpng2_info.height; ++row) {
+ yidx = row % bgscale;
+ if (yidx > hmax)
+ yidx = bgscale-1 - yidx;
+ dest = bg_data + row*bg_rowbytes;
+ for (i = 0; i < rpng2_info.width; ++i) {
+ xidx = i % bgscale;
+ if (xidx > hmax)
+ xidx = bgscale-1 - xidx;
+ k = xidx + yidx;
+ *dest++ = (k*r1 + (max-k)*r2) / max;
+ *dest++ = (k*g1 + (max-k)*g2) / max;
+ *dest++ = (k*b1 + (max-k)*b2) / max;
+ }
+ }
+
+/*---------------------------------------------------------------------------
+ Radial "starburst" with azimuthal sinusoids; [eventually number of sinu-
+ soids will equal bgscale?]. This one is slow but very cool. Code con-
+ tributed by Pieter S. van der Meulen (originally in Smalltalk).
+ ---------------------------------------------------------------------------*/
+
+ } else if ((bg[pat].type & 0x07) == 2) {
+ uch ch;
+ int ii, x, y, hw, hh, grayspot;
+ double freq, rotate, saturate, gray, intensity;
+ double angle=0.0, aoffset=0.0, maxDist, dist;
+ double red=0.0, green=0.0, blue=0.0, hue, s, v, f, p, q, t;
+
+ fprintf(stderr, "%s: computing radial background...",
+ PROGNAME);
+ fflush(stderr);
+
+ hh = rpng2_info.height / 2;
+ hw = rpng2_info.width / 2;
+
+ /* variables for radial waves:
+ * aoffset: number of degrees to rotate hue [CURRENTLY NOT USED]
+ * freq: number of color beams originating from the center
+ * grayspot: size of the graying center area (anti-alias)
+ * rotate: rotation of the beams as a function of radius
+ * saturate: saturation of beams' shape azimuthally
+ */
+ angle = CLIP(angle, 0.0, 360.0);
+ grayspot = CLIP(bg[pat].bg_gray, 1, (hh + hw));
+ freq = MAX((double)bg[pat].bg_freq, 0.0);
+ saturate = (double)bg[pat].bg_bsat * 0.1;
+ rotate = (double)bg[pat].bg_brot * 0.1;
+ gray = 0.0;
+ intensity = 0.0;
+ maxDist = (double)((hw*hw) + (hh*hh));
+
+ for (row = 0; row < rpng2_info.height; ++row) {
+ y = row - hh;
+ dest = bg_data + row*bg_rowbytes;
+ for (i = 0; i < rpng2_info.width; ++i) {
+ x = i - hw;
+ angle = (x == 0)? PI_2 : atan((double)y / (double)x);
+ gray = (double)MAX(ABS(y), ABS(x)) / grayspot;
+ gray = MIN(1.0, gray);
+ dist = (double)((x*x) + (y*y)) / maxDist;
+ intensity = cos((angle+(rotate*dist*PI)) * freq) *
+ gray * saturate;
+ intensity = (MAX(MIN(intensity,1.0),-1.0) + 1.0) * 0.5;
+ hue = (angle + PI) * INV_PI_360 + aoffset;
+ s = gray * ((double)(ABS(x)+ABS(y)) / (double)(hw + hh));
+ s = MIN(MAX(s,0.0), 1.0);
+ v = MIN(MAX(intensity,0.0), 1.0);
+
+ if (s == 0.0) {
+ ch = (uch)(v * 255.0);
+ *dest++ = ch;
+ *dest++ = ch;
+ *dest++ = ch;
+ } else {
+ if ((hue < 0.0) || (hue >= 360.0))
+ hue -= (((int)(hue / 360.0)) * 360.0);
+ hue /= 60.0;
+ ii = (int)hue;
+ f = hue - (double)ii;
+ p = (1.0 - s) * v;
+ q = (1.0 - (s * f)) * v;
+ t = (1.0 - (s * (1.0 - f))) * v;
+ if (ii == 0) { red = v; green = t; blue = p; }
+ else if (ii == 1) { red = q; green = v; blue = p; }
+ else if (ii == 2) { red = p; green = v; blue = t; }
+ else if (ii == 3) { red = p; green = q; blue = v; }
+ else if (ii == 4) { red = t; green = p; blue = v; }
+ else if (ii == 5) { red = v; green = p; blue = q; }
+ *dest++ = (uch)(red * 255.0);
+ *dest++ = (uch)(green * 255.0);
+ *dest++ = (uch)(blue * 255.0);
+ }
+ }
+ }
+ fprintf(stderr, "done.\n");
+ fflush(stderr);
+ }
+
+/*---------------------------------------------------------------------------
+ Blast background image to display buffer before beginning PNG decode;
+ calling function will handle invalidation and UpdateWindow() call.
+ ---------------------------------------------------------------------------*/
+
+ for (row = 0; row < rpng2_info.height; ++row) {
+ src = bg_data + row*bg_rowbytes;
+ dest = wimage_data + row*wimage_rowbytes;
+ for (i = rpng2_info.width; i > 0; --i) {
+ r1 = *src++;
+ g1 = *src++;
+ b1 = *src++;
+ *dest++ = b1;
+ *dest++ = g1; /* note reverse order */
+ *dest++ = r1;
+ }
+ }
+
+ return 0;
+
+} /* end function rpng2_win_load_bg_image() */
+
+
+
+
+
+static void rpng2_win_display_row(ulg row)
+{
+ uch bg_red = rpng2_info.bg_red;
+ uch bg_green = rpng2_info.bg_green;
+ uch bg_blue = rpng2_info.bg_blue;
+ uch *src, *src2=NULL, *dest;
+ uch r, g, b, a;
+ ulg i;
+ static int rows=0;
+ static ulg firstrow;
+
+/*---------------------------------------------------------------------------
+ rows and firstrow simply track how many rows (and which ones) have not
+ yet been displayed; alternatively, we could call InvalidateRect() for
+ every row and not bother with the records-keeping.
+ ---------------------------------------------------------------------------*/
+
+ Trace((stderr, "beginning rpng2_win_display_row()\n"))
+
+ if (rows == 0)
+ firstrow = row; /* first row not yet displayed */
+
+ ++rows; /* count of rows received but not yet displayed */
+
+/*---------------------------------------------------------------------------
+ Aside from the use of the rpng2_info struct and the lack of an outer
+ loop (over rows), this routine is identical to rpng_win_display_image()
+ in the non-progressive version of the program.
+ ---------------------------------------------------------------------------*/
+
+ src = rpng2_info.image_data + row*rpng2_info.rowbytes;
+ if (bg_image)
+ src2 = bg_data + row*bg_rowbytes;
+ dest = wimage_data + row*wimage_rowbytes;
+
+ if (rpng2_info.channels == 3) {
+ for (i = rpng2_info.width; i > 0; --i) {
+ r = *src++;
+ g = *src++;
+ b = *src++;
+ *dest++ = b;
+ *dest++ = g; /* note reverse order */
+ *dest++ = r;
+ }
+ } else /* if (rpng2_info.channels == 4) */ {
+ for (i = rpng2_info.width; i > 0; --i) {
+ r = *src++;
+ g = *src++;
+ b = *src++;
+ a = *src++;
+ if (bg_image) {
+ bg_red = *src2++;
+ bg_green = *src2++;
+ bg_blue = *src2++;
+ }
+ if (a == 255) {
+ *dest++ = b;
+ *dest++ = g;
+ *dest++ = r;
+ } else if (a == 0) {
+ *dest++ = bg_blue;
+ *dest++ = bg_green;
+ *dest++ = bg_red;
+ } else {
+ /* this macro (copied from png.h) composites the
+ * foreground and background values and puts the
+ * result into the first argument; there are no
+ * side effects with the first argument */
+ alpha_composite(*dest++, b, a, bg_blue);
+ alpha_composite(*dest++, g, a, bg_green);
+ alpha_composite(*dest++, r, a, bg_red);
+ }
+ }
+ }
+
+/*---------------------------------------------------------------------------
+ Display after every 16 rows or when on last row. (Region may include
+ previously displayed lines due to interlacing--i.e., not contiguous.)
+ ---------------------------------------------------------------------------*/
+
+ if ((rows & 0xf) == 0 || row == rpng2_info.height-1) {
+ RECT rect;
+
+ rect.left = 0L;
+ rect.top = (LONG)firstrow;
+ rect.right = (LONG)rpng2_info.width; /* possibly off by one? */
+ rect.bottom = (LONG)row + 1L; /* possibly off by one? */
+ InvalidateRect(global_hwnd, &rect, FALSE);
+ UpdateWindow(global_hwnd); /* similar to XFlush() */
+ rows = 0;
+ }
+
+} /* end function rpng2_win_display_row() */
+
+
+
+
+
+static void rpng2_win_finish_display()
+{
+ Trace((stderr, "beginning rpng2_win_finish_display()\n"))
+
+ /* last row has already been displayed by rpng2_win_display_row(), so
+ * we have nothing to do here except set a flag and let the user know
+ * that the image is done */
+
+ rpng2_info.state = kDone;
+ printf(
+#ifndef __CYGWIN__
+ "Done. Press Q, Esc or mouse button 1 (within image window) to quit.\n"
+#else
+ "Done. Press mouse button 1 (within image window) to quit.\n"
+#endif
+ );
+ fflush(stdout);
+}
+
+
+
+
+
+static void rpng2_win_cleanup()
+{
+ if (bg_image && bg_data) {
+ free(bg_data);
+ bg_data = NULL;
+ }
+
+ if (rpng2_info.image_data) {
+ free(rpng2_info.image_data);
+ rpng2_info.image_data = NULL;
+ }
+
+ if (rpng2_info.row_pointers) {
+ free(rpng2_info.row_pointers);
+ rpng2_info.row_pointers = NULL;
+ }
+
+ if (dib) {
+ free(dib);
+ dib = NULL;
+ }
+}
+
+
+
+
+
+LRESULT CALLBACK rpng2_win_wndproc(HWND hwnd, UINT iMsg, WPARAM wP, LPARAM lP)
+{
+ HDC hdc;
+ PAINTSTRUCT ps;
+ int rc;
+
+ switch (iMsg) {
+ case WM_CREATE:
+ /* one-time processing here, if any */
+ return 0;
+
+ case WM_PAINT:
+ hdc = BeginPaint(hwnd, &ps);
+ rc = StretchDIBits(hdc, 0, 0, rpng2_info.width, rpng2_info.height,
+ 0, 0, rpng2_info.width, rpng2_info.height,
+ wimage_data, (BITMAPINFO *)bmih,
+ 0, SRCCOPY);
+ EndPaint(hwnd, &ps);
+ return 0;
+
+ /* wait for the user to tell us when to quit */
+ case WM_CHAR:
+ switch (wP) { /* only need one, so ignore repeat count */
+ case 'q':
+ case 'Q':
+ case 0x1B: /* Esc key */
+ PostQuitMessage(0);
+ }
+ return 0;
+
+ case WM_LBUTTONDOWN: /* another way of quitting */
+ case WM_DESTROY:
+ PostQuitMessage(0);
+ return 0;
+ }
+
+ return DefWindowProc(hwnd, iMsg, wP, lP);
+}
diff --git a/libpng/contrib/gregbook/rpng2-x.c b/libpng/contrib/gregbook/rpng2-x.c
new file mode 100644
index 0000000..0c8ddeb
--- /dev/null
+++ b/libpng/contrib/gregbook/rpng2-x.c
@@ -0,0 +1,2134 @@
+/*---------------------------------------------------------------------------
+
+ rpng2 - progressive-model PNG display program rpng2-x.c
+
+ This program decodes and displays PNG files progressively, as if it were
+ a web browser (though the front end is only set up to read from files).
+ It supports gamma correction, user-specified background colors, and user-
+ specified background patterns (for transparent images). This version is
+ for the X Window System (tested by the author under Unix and by Martin
+ Zinser under OpenVMS; may work under OS/2 with a little tweaking).
+
+ Thanks to Adam Costello and Pieter S. van der Meulen for the "diamond"
+ and "radial waves" patterns, respectively.
+
+ to do (someday, maybe):
+ - fix expose/redraw code: don't draw entire row if only part exposed
+ - 8-bit (colormapped) X support
+ - finish resizable checkerboard-gradient (sizes 4-128?)
+ - use %.1023s to simplify truncation of title-bar string?
+
+ ---------------------------------------------------------------------------
+
+ Changelog:
+ - 1.01: initial public release
+ - 1.02: modified to allow abbreviated options; fixed char/uchar mismatch
+ - 1.10: added support for non-default visuals; fixed X pixel-conversion
+ - 1.11: added -usleep option for demos; fixed command-line parsing bug
+ - 1.12: added -pause option for demos and testing
+ - 1.20: added runtime MMX-enabling/disabling and new -mmx* options
+ - 1.21: fixed some small X memory leaks (thanks to François Petitjean)
+ - 1.22: fixed XFreeGC() crash bug (thanks to Patrick Welche)
+ - 1.23: added -bgpat 0 mode (std white/gray checkerboard, 8x8 squares)
+ - 1.30: added -loop option for -bgpat (ifdef FEATURE_LOOP); fixed bpp =
+ 24; added support for X resources (thanks to Gerhard Niklasch)
+ - 1.31: added code to skip unused chunks (thanks to Glenn Randers-Pehrson)
+ - 1.32: added AMD64/EM64T support (__x86_64__); added basic expose/redraw
+ handling
+ - 2.00: dual-licensed (added GNU GPL)
+ - 2.01: fixed 64-bit typo in readpng2.c; fixed -pause usage description
+ - 2.02: fixed improper display of usage screen on PNG error(s); fixed
+ unexpected-EOF and file-read-error cases; fixed Trace() cut-and-
+ paste bugs
+ - 2.03: deleted runtime MMX-enabling/disabling and obsolete -mmx* options
+ - 2.04: Added "void(foo);" statements to quiet pedantic compiler warnings
+ about unused variables (GR-P)
+ - 2.05: Use nanosleep() instead of usleep(), which is deprecated (GR-P).
+ ---------------------------------------------------------------------------
+
+ Copyright (c) 1998-2010, 2014-2015 Greg Roelofs. All rights reserved.
+
+ This software is provided "as is," without warranty of any kind,
+ express or implied. In no event shall the author or contributors
+ be held liable for any damages arising in any way from the use of
+ this software.
+
+ The contents of this file are DUAL-LICENSED. You may modify and/or
+ redistribute this software according to the terms of one of the
+ following two licenses (at your option):
+
+
+ LICENSE 1 ("BSD-like with advertising clause"):
+
+ Permission is granted to anyone to use this software for any purpose,
+ including commercial applications, and to alter it and redistribute
+ it freely, subject to the following restrictions:
+
+ 1. Redistributions of source code must retain the above copyright
+ notice, disclaimer, and this list of conditions.
+ 2. Redistributions in binary form must reproduce the above copyright
+ notice, disclaimer, and this list of conditions in the documenta-
+ tion and/or other materials provided with the distribution.
+ 3. All advertising materials mentioning features or use of this
+ software must display the following acknowledgment:
+
+ This product includes software developed by Greg Roelofs
+ and contributors for the book, "PNG: The Definitive Guide,"
+ published by O'Reilly and Associates.
+
+
+ LICENSE 2 (GNU GPL v2 or later):
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ ---------------------------------------------------------------------------*/
+
+#define PROGNAME "rpng2-x"
+#define LONGNAME "Progressive PNG Viewer for X"
+#define VERSION "2.04 of 15 June 2014"
+#define RESNAME "rpng2" /* our X resource application name */
+#define RESCLASS "Rpng" /* our X resource class name */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <string.h>
+#include <setjmp.h> /* for jmpbuf declaration in readpng2.h */
+#include <time.h>
+#include <math.h> /* only for PvdM background code */
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+#include <X11/Xos.h>
+#include <X11/keysym.h> /* defines XK_* macros */
+
+#if _POSIX_C_SOURCE >= 199309L /* have nanosleep() */
+# undef usleep
+# define usleep(usec) { \
+ struct timespec ts; \
+ ts.tv_sec = 0; \
+ ts.tv_nsec = (usec) * 1000; \
+ nanosleep(&ts, NULL); }
+# endif
+
+#ifndef usleep /* have neither nanosleep() nor usleep() */
+# define usleep(x) sleep(((x)+499999)/1000000)
+#endif
+
+#ifdef VMS
+# include <unistd.h>
+#endif
+
+/* all for PvdM background code: */
+#ifndef PI
+# define PI 3.141592653589793238
+#endif
+#define PI_2 (PI*0.5)
+#define INV_PI_360 (360.0 / PI)
+#define MAX(a,b) (a>b?a:b)
+#define MIN(a,b) (a<b?a:b)
+#define CLIP(a,min,max) MAX(min,MIN((a),max))
+#define ABS(a) ((a)<0?-(a):(a))
+#define CLIP8P(c) MAX(0,(MIN((c),255))) /* 8-bit pos. integer (uch) */
+#define ROUNDF(f) ((int)(f + 0.5))
+
+#define QUIT(e,k) ((e.type == ButtonPress && e.xbutton.button == Button1) || \
+ (e.type == KeyPress && /* v--- or 1 for shifted keys */ \
+ ((k = XLookupKeysym(&e.xkey, 0)) == XK_q || k == XK_Escape)))
+
+#define NO_24BIT_MASKS /* undef case not fully written--only for redisplay() */
+
+#define rgb1_max bg_freq
+#define rgb1_min bg_gray
+#define rgb2_max bg_bsat
+#define rgb2_min bg_brot
+
+/* #define DEBUG */ /* this enables the Trace() macros */
+
+#include "readpng2.h" /* typedefs, common macros, readpng2 prototypes */
+
+
+/* could just include png.h, but this macro is the only thing we need
+ * (name and typedefs changed to local versions); note that side effects
+ * only happen with alpha (which could easily be avoided with
+ * "ush acopy = (alpha);") */
+
+#define alpha_composite(composite, fg, alpha, bg) { \
+ ush temp = ((ush)(fg)*(ush)(alpha) + \
+ (ush)(bg)*(ush)(255 - (ush)(alpha)) + (ush)128); \
+ (composite) = (uch)((temp + (temp >> 8)) >> 8); \
+}
+
+
+#define INBUFSIZE 4096 /* with pseudo-timing on (1 sec delay/block), this
+ * block size corresponds roughly to a download
+ * speed 10% faster than theoretical 33.6K maximum
+ * (assuming 8 data bits, 1 stop bit and no other
+ * overhead) */
+
+/* local prototypes */
+static void rpng2_x_init (void);
+static int rpng2_x_create_window (void);
+static int rpng2_x_load_bg_image (void);
+static void rpng2_x_display_row (ulg row);
+static void rpng2_x_finish_display (void);
+static void rpng2_x_redisplay_image (ulg startcol, ulg startrow,
+ ulg width, ulg height);
+#ifdef FEATURE_LOOP
+static void rpng2_x_reload_bg_image (void);
+static int is_number (char *p);
+#endif
+static void rpng2_x_cleanup (void);
+static int rpng2_x_msb (ulg u32val);
+
+
+static char titlebar[1024], *window_name = titlebar;
+static char *appname = LONGNAME;
+static char *icon_name = PROGNAME;
+static char *res_name = RESNAME;
+static char *res_class = RESCLASS;
+static char *filename;
+static FILE *infile;
+
+static mainprog_info rpng2_info;
+
+static uch inbuf[INBUFSIZE];
+static int incount;
+
+static int pat = 6; /* must be less than num_bgpat */
+static int bg_image = 0;
+static int bgscale, bgscale_default = 16;
+static ulg bg_rowbytes;
+static uch *bg_data;
+
+int pause_after_pass = FALSE;
+int demo_timing = FALSE;
+ulg usleep_duration = 0L;
+
+static struct rgb_color {
+ uch r, g, b;
+} rgb[] = {
+ { 0, 0, 0}, /* 0: black */
+ {255, 255, 255}, /* 1: white */
+ {173, 132, 57}, /* 2: tan */
+ { 64, 132, 0}, /* 3: medium green */
+ {189, 117, 1}, /* 4: gold */
+ {253, 249, 1}, /* 5: yellow */
+ { 0, 0, 255}, /* 6: blue */
+ { 0, 0, 120}, /* 7: medium blue */
+ {255, 0, 255}, /* 8: magenta */
+ { 64, 0, 64}, /* 9: dark magenta */
+ {255, 0, 0}, /* 10: red */
+ { 64, 0, 0}, /* 11: dark red */
+ {255, 127, 0}, /* 12: orange */
+ {192, 96, 0}, /* 13: darker orange */
+ { 24, 60, 0}, /* 14: dark green-yellow */
+ { 85, 125, 200}, /* 15: ice blue */
+ {192, 192, 192} /* 16: Netscape/Mosaic gray */
+};
+/* not used for now, but should be for error-checking:
+static int num_rgb = sizeof(rgb) / sizeof(struct rgb_color);
+ */
+
+/*
+ This whole struct is a fairly cheesy way to keep the number of
+ command-line options to a minimum. The radial-waves background
+ type is a particularly poor fit to the integer elements of the
+ struct...but a few macros and a little fixed-point math will do
+ wonders for ya.
+
+ type bits:
+ F E D C B A 9 8 7 6 5 4 3 2 1 0
+ | | | | |
+ | | +-+-+-- 0 = sharp-edged checkerboard
+ | | 1 = soft diamonds
+ | | 2 = radial waves
+ | | 3-7 = undefined
+ | +-- gradient #2 inverted?
+ +-- alternating columns inverted?
+ */
+static struct background_pattern {
+ ush type;
+ int rgb1_max, rgb1_min; /* or bg_freq, bg_gray */
+ int rgb2_max, rgb2_min; /* or bg_bsat, bg_brot (both scaled by 10)*/
+} bg[] = {
+ {0, 1,1, 16,16}, /* checkered: white vs. light gray (basic) */
+ {0+8, 2,0, 1,15}, /* checkered: tan/black vs. white/ice blue */
+ {0+24, 2,0, 1,0}, /* checkered: tan/black vs. white/black */
+ {0+8, 4,5, 0,2}, /* checkered: gold/yellow vs. black/tan */
+ {0+8, 4,5, 0,6}, /* checkered: gold/yellow vs. black/blue */
+ {0, 7,0, 8,9}, /* checkered: deep blue/black vs. magenta */
+ {0+8, 13,0, 5,14}, /* checkered: orange/black vs. yellow */
+ {0+8, 12,0, 10,11}, /* checkered: orange/black vs. red */
+ {1, 7,0, 8,0}, /* diamonds: deep blue/black vs. magenta */
+ {1, 12,0, 11,0}, /* diamonds: orange vs. dark red */
+ {1, 10,0, 7,0}, /* diamonds: red vs. medium blue */
+ {1, 4,0, 5,0}, /* diamonds: gold vs. yellow */
+ {1, 3,0, 0,0}, /* diamonds: medium green vs. black */
+ {2, 16, 100, 20, 0}, /* radial: ~hard radial color-beams */
+ {2, 18, 100, 10, 2}, /* radial: soft, curved radial color-beams */
+ {2, 16, 256, 100, 250}, /* radial: very tight spiral */
+ {2, 10000, 256, 11, 0} /* radial: dipole-moire' (almost fractal) */
+};
+static int num_bgpat = sizeof(bg) / sizeof(struct background_pattern);
+
+
+/* X-specific variables */
+static char *displayname;
+static XImage *ximage;
+static Display *display;
+static int depth;
+static Visual *visual;
+static XVisualInfo *visual_list;
+static int RShift, GShift, BShift;
+static ulg RMask, GMask, BMask;
+static Window window;
+static GC gc;
+static Colormap colormap;
+
+static int have_nondefault_visual = FALSE;
+static int have_colormap = FALSE;
+static int have_window = FALSE;
+static int have_gc = FALSE;
+
+
+
+
+int main(int argc, char **argv)
+{
+#ifdef sgi
+ char tmpline[80];
+#endif
+ char *p, *bgstr = NULL;
+ int rc, alen, flen;
+ int error = 0;
+ int timing = FALSE;
+ int have_bg = FALSE;
+#ifdef FEATURE_LOOP
+ int loop = FALSE;
+ long loop_interval = -1; /* seconds (100,000 max) */
+#endif
+ double LUT_exponent; /* just the lookup table */
+ double CRT_exponent = 2.2; /* just the monitor */
+ double default_display_exponent; /* whole display system */
+ XEvent e;
+ KeySym k;
+
+
+ /* First initialize a few things, just to be sure--memset takes care of
+ * default background color (black), booleans (FALSE), pointers (NULL),
+ * etc. */
+
+ displayname = (char *)NULL;
+ filename = (char *)NULL;
+ memset(&rpng2_info, 0, sizeof(mainprog_info));
+
+
+ /* Set the default value for our display-system exponent, i.e., the
+ * product of the CRT exponent and the exponent corresponding to
+ * the frame-buffer's lookup table (LUT), if any. This is not an
+ * exhaustive list of LUT values (e.g., OpenStep has a lot of weird
+ * ones), but it should cover 99% of the current possibilities. */
+
+#if defined(NeXT)
+ /* third-party utilities can modify the default LUT exponent */
+ LUT_exponent = 1.0 / 2.2;
+ /*
+ if (some_next_function_that_returns_gamma(&next_gamma))
+ LUT_exponent = 1.0 / next_gamma;
+ */
+#elif defined(sgi)
+ LUT_exponent = 1.0 / 1.7;
+ /* there doesn't seem to be any documented function to
+ * get the "gamma" value, so we do it the hard way */
+ infile = fopen("/etc/config/system.glGammaVal", "r");
+ if (infile) {
+ double sgi_gamma;
+
+ fgets(tmpline, 80, infile);
+ fclose(infile);
+ sgi_gamma = atof(tmpline);
+ if (sgi_gamma > 0.0)
+ LUT_exponent = 1.0 / sgi_gamma;
+ }
+#elif defined(Macintosh)
+ LUT_exponent = 1.8 / 2.61;
+ /*
+ if (some_mac_function_that_returns_gamma(&mac_gamma))
+ LUT_exponent = mac_gamma / 2.61;
+ */
+#else
+ LUT_exponent = 1.0; /* assume no LUT: most PCs */
+#endif
+
+ /* the defaults above give 1.0, 1.3, 1.5 and 2.2, respectively: */
+ default_display_exponent = LUT_exponent * CRT_exponent;
+
+
+ /* If the user has set the SCREEN_GAMMA environment variable as suggested
+ * (somewhat imprecisely) in the libpng documentation, use that; otherwise
+ * use the default value we just calculated. Either way, the user may
+ * override this via a command-line option. */
+
+ if ((p = getenv("SCREEN_GAMMA")) != NULL)
+ rpng2_info.display_exponent = atof(p);
+ else
+ rpng2_info.display_exponent = default_display_exponent;
+
+
+ /* Now parse the command line for options and the PNG filename. */
+
+ while (*++argv && !error) {
+ if (!strncmp(*argv, "-display", 2)) {
+ if (!*++argv)
+ ++error;
+ else
+ displayname = *argv;
+ } else if (!strncmp(*argv, "-gamma", 2)) {
+ if (!*++argv)
+ ++error;
+ else {
+ rpng2_info.display_exponent = atof(*argv);
+ if (rpng2_info.display_exponent <= 0.0)
+ ++error;
+ }
+ } else if (!strncmp(*argv, "-bgcolor", 4)) {
+ if (!*++argv)
+ ++error;
+ else {
+ bgstr = *argv;
+ if (strlen(bgstr) != 7 || bgstr[0] != '#')
+ ++error;
+ else {
+ have_bg = TRUE;
+ bg_image = FALSE;
+ }
+ }
+ } else if (!strncmp(*argv, "-bgpat", 4)) {
+ if (!*++argv)
+ ++error;
+ else {
+ pat = atoi(*argv);
+ if (pat >= 0 && pat < num_bgpat) {
+ bg_image = TRUE;
+ have_bg = FALSE;
+ } else
+ ++error;
+ }
+ } else if (!strncmp(*argv, "-usleep", 2)) {
+ if (!*++argv)
+ ++error;
+ else {
+ usleep_duration = (ulg)atol(*argv);
+ demo_timing = TRUE;
+ }
+ } else if (!strncmp(*argv, "-pause", 2)) {
+ pause_after_pass = TRUE;
+ } else if (!strncmp(*argv, "-timing", 2)) {
+ timing = TRUE;
+#ifdef FEATURE_LOOP
+ } else if (!strncmp(*argv, "-loop", 2)) {
+ loop = TRUE;
+ if (!argv[1] || !is_number(argv[1]))
+ loop_interval = 2;
+ else {
+ ++argv;
+ loop_interval = atol(*argv);
+ if (loop_interval < 0)
+ loop_interval = 2;
+ else if (loop_interval > 100000) /* bit more than one day */
+ loop_interval = 100000;
+ }
+#endif
+ } else {
+ if (**argv != '-') {
+ filename = *argv;
+ if (argv[1]) /* shouldn't be any more args after filename */
+ ++error;
+ } else
+ ++error; /* not expecting any other options */
+ }
+ }
+
+ if (!filename)
+ ++error;
+
+
+ /* print usage screen if any errors up to this point */
+
+ if (error) {
+ fprintf(stderr, "\n%s %s: %s\n\n", PROGNAME, VERSION, appname);
+ readpng2_version_info();
+ fprintf(stderr, "\n"
+ "Usage: ");
+ fprintf(stderr,
+ "%s [-display xdpy] [-gamma exp] [-bgcolor bg | -bgpat pat]\n"
+ " %*s [-usleep dur | -timing] [-pause]\n",
+ PROGNAME, (int)strlen(PROGNAME), " ");
+ fprintf(stderr,
+#ifdef FEATURE_LOOP
+ " [-loop [sec]]"
+#endif
+ " file.png\n\n");
+ fprintf(stderr,
+ " xdpy\tname of the target X display (e.g., ``hostname:0'')\n"
+ " exp \ttransfer-function exponent (``gamma'') of the display\n"
+ "\t\t system in floating-point format (e.g., ``%.1f''); equal\n"
+ "\t\t to the product of the lookup-table exponent (varies)\n",
+ default_display_exponent);
+ fprintf(stderr,
+ "\t\t and the CRT exponent (usually 2.2); must be positive\n"
+ " bg \tdesired background color in 7-character hex RGB format\n"
+ "\t\t (e.g., ``#ff7700'' for orange: same as HTML colors);\n"
+ "\t\t used with transparent images; overrides -bgpat\n"
+ " pat \tdesired background pattern number (0-%d); used with\n"
+ "\t\t transparent images; overrides -bgcolor\n",
+ num_bgpat-1);
+#ifdef FEATURE_LOOP
+ fprintf(stderr,
+ " -loop\tloops through background images after initial display\n"
+ "\t\t is complete (depends on -bgpat)\n"
+ " sec \tseconds to display each background image (default = 2)\n");
+#endif
+ fprintf(stderr,
+ " dur \tduration in microseconds to wait after displaying each\n"
+ "\t\t row (for demo purposes)\n"
+ " -timing\tenables delay for every block read, to simulate modem\n"
+ "\t\t download of image (~36 Kbps)\n"
+ " -pause\tpauses after displaying each pass until mouse clicked\n"
+ "\nPress Q, Esc or mouse button 1 (within image window, after image\n"
+ "is displayed) to quit.\n");
+ exit(1);
+ }
+
+ if (!(infile = fopen(filename, "rb"))) {
+ fprintf(stderr, PROGNAME ": can't open PNG file [%s]\n", filename);
+ ++error;
+ } else {
+ incount = fread(inbuf, 1, INBUFSIZE, infile);
+ if (incount < 8 || !readpng2_check_sig(inbuf, 8)) {
+ fprintf(stderr, PROGNAME
+ ": [%s] is not a PNG file: incorrect signature\n",
+ filename);
+ ++error;
+ } else if ((rc = readpng2_init(&rpng2_info)) != 0) {
+ switch (rc) {
+ case 2:
+ fprintf(stderr, PROGNAME
+ ": [%s] has bad IHDR (libpng longjmp)\n", filename);
+ break;
+ case 4:
+ fprintf(stderr, PROGNAME ": insufficient memory\n");
+ break;
+ default:
+ fprintf(stderr, PROGNAME
+ ": unknown readpng2_init() error\n");
+ break;
+ }
+ ++error;
+ } else {
+ Trace((stderr, "about to call XOpenDisplay()\n"))
+ display = XOpenDisplay(displayname);
+ if (!display) {
+ readpng2_cleanup(&rpng2_info);
+ fprintf(stderr, PROGNAME ": can't open X display [%s]\n",
+ displayname? displayname : "default");
+ ++error;
+ }
+ }
+ if (error)
+ fclose(infile);
+ }
+
+
+ if (error) {
+ fprintf(stderr, PROGNAME ": aborting.\n");
+ exit(2);
+ }
+
+
+ /* set the title-bar string, but make sure buffer doesn't overflow */
+
+ alen = strlen(appname);
+ flen = strlen(filename);
+ if (alen + flen + 3 > 1023)
+ sprintf(titlebar, "%s: ...%s", appname, filename+(alen+flen+6-1023));
+ else
+ sprintf(titlebar, "%s: %s", appname, filename);
+
+
+ /* set some final rpng2_info variables before entering main data loop */
+
+ if (have_bg) {
+ unsigned r, g, b; /* this approach quiets compiler warnings */
+
+ sscanf(bgstr+1, "%2x%2x%2x", &r, &g, &b);
+ rpng2_info.bg_red = (uch)r;
+ rpng2_info.bg_green = (uch)g;
+ rpng2_info.bg_blue = (uch)b;
+ } else
+ rpng2_info.need_bgcolor = TRUE;
+
+ rpng2_info.state = kPreInit;
+ rpng2_info.mainprog_init = rpng2_x_init;
+ rpng2_info.mainprog_display_row = rpng2_x_display_row;
+ rpng2_info.mainprog_finish_display = rpng2_x_finish_display;
+
+
+ /* OK, this is the fun part: call readpng2_decode_data() at the start of
+ * the loop to deal with our first buffer of data (read in above to verify
+ * that the file is a PNG image), then loop through the file and continue
+ * calling the same routine to handle each chunk of data. It in turn
+ * passes the data to libpng, which will invoke one or more of our call-
+ * backs as decoded data become available. We optionally call sleep() for
+ * one second per iteration to simulate downloading the image via an analog
+ * modem. */
+
+ for (;;) {
+ Trace((stderr, "about to call readpng2_decode_data()\n"))
+ if (readpng2_decode_data(&rpng2_info, inbuf, incount))
+ ++error;
+ Trace((stderr, "done with readpng2_decode_data()\n"))
+
+ if (error || incount != INBUFSIZE || rpng2_info.state == kDone) {
+ if (rpng2_info.state == kDone) {
+ Trace((stderr, "done decoding PNG image\n"))
+ } else if (ferror(infile)) {
+ fprintf(stderr, PROGNAME
+ ": error while reading PNG image file\n");
+ exit(3);
+ } else if (feof(infile)) {
+ fprintf(stderr, PROGNAME ": end of file reached "
+ "(unexpectedly) while reading PNG image file\n");
+ exit(3);
+ } else /* if (error) */ {
+ /* will print error message below */
+ }
+ break;
+ }
+
+ if (timing)
+ sleep(1);
+
+ incount = fread(inbuf, 1, INBUFSIZE, infile);
+ }
+
+
+ /* clean up PNG stuff and report any decoding errors */
+
+ fclose(infile);
+ Trace((stderr, "about to call readpng2_cleanup()\n"))
+ readpng2_cleanup(&rpng2_info);
+
+ if (error) {
+ fprintf(stderr, PROGNAME ": libpng error while decoding PNG image\n");
+ exit(3);
+ }
+
+
+#ifdef FEATURE_LOOP
+
+ if (loop && bg_image) {
+ Trace((stderr, "entering -loop loop (FEATURE_LOOP)\n"))
+ for (;;) {
+ int i, use_sleep;
+ struct timeval now, then;
+
+ /* get current time and add loop_interval to get target time */
+ if (gettimeofday(&then, NULL) == 0) {
+ then.tv_sec += loop_interval;
+ use_sleep = FALSE;
+ } else
+ use_sleep = TRUE;
+
+ /* do quick check for a quit event but don't wait for it */
+ /* GRR BUG: should also check for Expose events and redraw... */
+ if (XCheckMaskEvent(display, KeyPressMask | ButtonPressMask, &e))
+ if (QUIT(e,k))
+ break;
+
+ /* generate next background image */
+ if (++pat >= num_bgpat)
+ pat = 0;
+ rpng2_x_reload_bg_image();
+
+ /* wait for timeout, using whatever means are available */
+ if (use_sleep || gettimeofday(&now, NULL) != 0) {
+ for (i = loop_interval; i > 0; --i) {
+ sleep(1);
+ /* GRR BUG: also need to check for Expose (and redraw!) */
+ if (XCheckMaskEvent(display, KeyPressMask | ButtonPressMask,
+ &e) && QUIT(e,k))
+ break;
+ }
+ } else {
+ /* Y2038 BUG! */
+ if (now.tv_sec < then.tv_sec ||
+ (now.tv_sec == then.tv_sec && now.tv_usec < then.tv_usec))
+ {
+ int quit = FALSE;
+ long seconds_to_go = then.tv_sec - now.tv_sec;
+ long usleep_usec;
+
+ /* basically chew up most of remaining loop-interval with
+ * calls to sleep(1) interleaved with checks for quit
+ * events, but also recalc time-to-go periodically; when
+ * done, clean up any remaining time with usleep() call
+ * (could also use SIGALRM, but signals are a pain...) */
+ while (seconds_to_go-- > 1) {
+ int seconds_done = 0;
+
+ for (i = seconds_to_go; i > 0 && !quit; --i) {
+ sleep(1);
+ /* GRR BUG: need to check for Expose and redraw */
+ if (XCheckMaskEvent(display, KeyPressMask |
+ ButtonPressMask, &e) && QUIT(e,k))
+ quit = TRUE;
+ if (++seconds_done > 1000)
+ break; /* time to redo seconds_to_go meas. */
+ }
+ if (quit)
+ break;
+
+ /* OK, more than 1000 seconds since last check:
+ * correct the time-to-go measurement for drift */
+ if (gettimeofday(&now, NULL) == 0) {
+ if (now.tv_sec >= then.tv_sec)
+ break;
+ seconds_to_go = then.tv_sec - now.tv_sec;
+ } else
+ ++seconds_to_go; /* restore what we subtracted */
+ }
+ if (quit)
+ break; /* breaks outer do-loop, skips redisplay */
+
+ /* since difference between "now" and "then" is already
+ * eaten up to within a couple of seconds, don't need to
+ * worry about overflow--but might have overshot (neg.) */
+ if (gettimeofday(&now, NULL) == 0) {
+ usleep_usec = 1000000L*(then.tv_sec - now.tv_sec) +
+ then.tv_usec - now.tv_usec;
+ if (usleep_usec > 0)
+ usleep((ulg)usleep_usec);
+ }
+ }
+ }
+
+ /* composite image against new background and display (note that
+ * we do not take into account the time spent doing this...) */
+ rpng2_x_redisplay_image (0, 0, rpng2_info.width, rpng2_info.height);
+ }
+
+ } else /* FALL THROUGH and do the normal thing */
+
+#endif /* FEATURE_LOOP */
+
+ /* wait for the user to tell us when to quit */
+
+ if (rpng2_info.state >= kWindowInit) {
+ Trace((stderr, "entering final wait-for-quit-event loop\n"))
+ do {
+ XNextEvent(display, &e);
+ if (e.type == Expose) {
+ XExposeEvent *ex = (XExposeEvent *)&e;
+ rpng2_x_redisplay_image (ex->x, ex->y, ex->width, ex->height);
+ }
+ } while (!QUIT(e,k));
+ } else {
+ fprintf(stderr, PROGNAME ": init callback never called: probable "
+ "libpng error while decoding PNG metadata\n");
+ exit(4);
+ }
+
+
+ /* we're done: clean up all image and X resources and go away */
+
+ Trace((stderr, "about to call rpng2_x_cleanup()\n"))
+ rpng2_x_cleanup();
+
+ (void)argc; /* Unused */
+
+ return 0;
+}
+
+
+
+
+
+/* this function is called by readpng2_info_callback() in readpng2.c, which
+ * in turn is called by libpng after all of the pre-IDAT chunks have been
+ * read and processed--i.e., we now have enough info to finish initializing */
+
+static void rpng2_x_init(void)
+{
+ ulg i;
+ ulg rowbytes = rpng2_info.rowbytes;
+
+ Trace((stderr, "beginning rpng2_x_init()\n"))
+ Trace((stderr, " rowbytes = %d\n", rpng2_info.rowbytes))
+ Trace((stderr, " width = %ld\n", rpng2_info.width))
+ Trace((stderr, " height = %ld\n", rpng2_info.height))
+
+ rpng2_info.image_data = (uch *)malloc(rowbytes * rpng2_info.height);
+ if (!rpng2_info.image_data) {
+ readpng2_cleanup(&rpng2_info);
+ return;
+ }
+
+ rpng2_info.row_pointers = (uch **)malloc(rpng2_info.height * sizeof(uch *));
+ if (!rpng2_info.row_pointers) {
+ free(rpng2_info.image_data);
+ rpng2_info.image_data = NULL;
+ readpng2_cleanup(&rpng2_info);
+ return;
+ }
+
+ for (i = 0; i < rpng2_info.height; ++i)
+ rpng2_info.row_pointers[i] = rpng2_info.image_data + i*rowbytes;
+
+
+ /* do the basic X initialization stuff, make the window, and fill it with
+ * the user-specified, file-specified or default background color or
+ * pattern */
+
+ if (rpng2_x_create_window()) {
+
+ /* GRR TEMPORARY HACK: this is fundamentally no different from cases
+ * above; libpng should call our error handler to longjmp() back to us
+ * when png_ptr goes away. If we/it segfault instead, seems like a
+ * libpng bug... */
+
+ /* we're here via libpng callback, so if window fails, clean and bail */
+ readpng2_cleanup(&rpng2_info);
+ rpng2_x_cleanup();
+ exit(2);
+ }
+
+ rpng2_info.state = kWindowInit;
+}
+
+
+
+
+
+static int rpng2_x_create_window(void)
+{
+ ulg bg_red = rpng2_info.bg_red;
+ ulg bg_green = rpng2_info.bg_green;
+ ulg bg_blue = rpng2_info.bg_blue;
+ ulg bg_pixel = 0L;
+ ulg attrmask;
+ int need_colormap = FALSE;
+ int screen, pad;
+ uch *xdata;
+ Window root;
+ XEvent e;
+ XGCValues gcvalues;
+ XSetWindowAttributes attr;
+ XTextProperty windowName, *pWindowName = &windowName;
+ XTextProperty iconName, *pIconName = &iconName;
+ XVisualInfo visual_info;
+ XSizeHints *size_hints;
+ XWMHints *wm_hints;
+ XClassHint *class_hints;
+
+
+ Trace((stderr, "beginning rpng2_x_create_window()\n"))
+
+ screen = DefaultScreen(display);
+ depth = DisplayPlanes(display, screen);
+ root = RootWindow(display, screen);
+
+#ifdef DEBUG
+ XSynchronize(display, True);
+#endif
+
+ if (depth != 16 && depth != 24 && depth != 32) {
+ int visuals_matched = 0;
+
+ Trace((stderr, "default depth is %d: checking other visuals\n",
+ depth))
+
+ /* 24-bit first */
+ visual_info.screen = screen;
+ visual_info.depth = 24;
+ visual_list = XGetVisualInfo(display,
+ VisualScreenMask | VisualDepthMask, &visual_info, &visuals_matched);
+ if (visuals_matched == 0) {
+/* GRR: add 15-, 16- and 32-bit TrueColor visuals (also DirectColor?) */
+ fprintf(stderr, "default screen depth %d not supported, and no"
+ " 24-bit visuals found\n", depth);
+ return 2;
+ }
+ Trace((stderr, "XGetVisualInfo() returned %d 24-bit visuals\n",
+ visuals_matched))
+ visual = visual_list[0].visual;
+ depth = visual_list[0].depth;
+/*
+ colormap_size = visual_list[0].colormap_size;
+ visual_class = visual->class;
+ visualID = XVisualIDFromVisual(visual);
+ */
+ have_nondefault_visual = TRUE;
+ need_colormap = TRUE;
+ } else {
+ XMatchVisualInfo(display, screen, depth, TrueColor, &visual_info);
+ visual = visual_info.visual;
+ }
+
+ RMask = visual->red_mask;
+ GMask = visual->green_mask;
+ BMask = visual->blue_mask;
+
+/* GRR: add/check 8-bit support */
+ if (depth == 8 || need_colormap) {
+ colormap = XCreateColormap(display, root, visual, AllocNone);
+ if (!colormap) {
+ fprintf(stderr, "XCreateColormap() failed\n");
+ return 2;
+ }
+ have_colormap = TRUE;
+ if (depth == 8)
+ bg_image = FALSE; /* gradient just wastes palette entries */
+ }
+ if (depth == 15 || depth == 16) {
+ RShift = 15 - rpng2_x_msb(RMask); /* these are right-shifts */
+ GShift = 15 - rpng2_x_msb(GMask);
+ BShift = 15 - rpng2_x_msb(BMask);
+ } else if (depth > 16) {
+ RShift = rpng2_x_msb(RMask) - 7; /* these are left-shifts */
+ GShift = rpng2_x_msb(GMask) - 7;
+ BShift = rpng2_x_msb(BMask) - 7;
+ }
+ if (depth >= 15 && (RShift < 0 || GShift < 0 || BShift < 0)) {
+ fprintf(stderr, "rpng2 internal logic error: negative X shift(s)!\n");
+ return 2;
+ }
+
+/*---------------------------------------------------------------------------
+ Finally, create the window.
+ ---------------------------------------------------------------------------*/
+
+ attr.backing_store = Always;
+ attr.event_mask = ExposureMask | KeyPressMask | ButtonPressMask;
+ attrmask = CWBackingStore | CWEventMask;
+ if (have_nondefault_visual) {
+ attr.colormap = colormap;
+ attr.background_pixel = 0;
+ attr.border_pixel = 1;
+ attrmask |= CWColormap | CWBackPixel | CWBorderPixel;
+ }
+
+ window = XCreateWindow(display, root, 0, 0, rpng2_info.width,
+ rpng2_info.height, 0, depth, InputOutput, visual, attrmask, &attr);
+
+ if (window == None) {
+ fprintf(stderr, "XCreateWindow() failed\n");
+ return 2;
+ } else
+ have_window = TRUE;
+
+ if (depth == 8)
+ XSetWindowColormap(display, window, colormap);
+
+ if (!XStringListToTextProperty(&window_name, 1, pWindowName))
+ pWindowName = NULL;
+ if (!XStringListToTextProperty(&icon_name, 1, pIconName))
+ pIconName = NULL;
+
+ /* OK if either hints allocation fails; XSetWMProperties() allows NULLs */
+
+ if ((size_hints = XAllocSizeHints()) != NULL) {
+ /* window will not be resizable */
+ size_hints->flags = PMinSize | PMaxSize;
+ size_hints->min_width = size_hints->max_width = (int)rpng2_info.width;
+ size_hints->min_height = size_hints->max_height =
+ (int)rpng2_info.height;
+ }
+
+ if ((wm_hints = XAllocWMHints()) != NULL) {
+ wm_hints->initial_state = NormalState;
+ wm_hints->input = True;
+ /* wm_hints->icon_pixmap = icon_pixmap; */
+ wm_hints->flags = StateHint | InputHint /* | IconPixmapHint */ ;
+ }
+
+ if ((class_hints = XAllocClassHint()) != NULL) {
+ class_hints->res_name = res_name;
+ class_hints->res_class = res_class;
+ }
+
+ XSetWMProperties(display, window, pWindowName, pIconName, NULL, 0,
+ size_hints, wm_hints, class_hints);
+
+ /* various properties and hints no longer needed; free memory */
+ if (pWindowName)
+ XFree(pWindowName->value);
+ if (pIconName)
+ XFree(pIconName->value);
+ if (size_hints)
+ XFree(size_hints);
+ if (wm_hints)
+ XFree(wm_hints);
+ if (class_hints)
+ XFree(class_hints);
+
+ XMapWindow(display, window);
+
+ gc = XCreateGC(display, window, 0, &gcvalues);
+ have_gc = TRUE;
+
+/*---------------------------------------------------------------------------
+ Allocate memory for the X- and display-specific version of the image.
+ ---------------------------------------------------------------------------*/
+
+ if (depth == 24 || depth == 32) {
+ xdata = (uch *)malloc(4*rpng2_info.width*rpng2_info.height);
+ pad = 32;
+ } else if (depth == 16) {
+ xdata = (uch *)malloc(2*rpng2_info.width*rpng2_info.height);
+ pad = 16;
+ } else /* depth == 8 */ {
+ xdata = (uch *)malloc(rpng2_info.width*rpng2_info.height);
+ pad = 8;
+ }
+
+ if (!xdata) {
+ fprintf(stderr, PROGNAME ": unable to allocate image memory\n");
+ return 4;
+ }
+
+ ximage = XCreateImage(display, visual, depth, ZPixmap, 0,
+ (char *)xdata, rpng2_info.width, rpng2_info.height, pad, 0);
+
+ if (!ximage) {
+ fprintf(stderr, PROGNAME ": XCreateImage() failed\n");
+ free(xdata);
+ return 3;
+ }
+
+ /* to avoid testing the byte order every pixel (or doubling the size of
+ * the drawing routine with a giant if-test), we arbitrarily set the byte
+ * order to MSBFirst and let Xlib worry about inverting things on little-
+ * endian machines (e.g., Linux/x86, old VAXen, etc.)--this is not the
+ * most efficient approach (the giant if-test would be better), but in
+ * the interest of clarity, we'll take the easy way out... */
+
+ ximage->byte_order = MSBFirst;
+
+/*---------------------------------------------------------------------------
+ Fill window with the specified background color (default is black) or
+ faked "background image" (but latter is disabled if 8-bit; gradients
+ just waste palette entries).
+ ---------------------------------------------------------------------------*/
+
+ if (bg_image)
+ rpng2_x_load_bg_image(); /* resets bg_image if fails */
+
+ if (!bg_image) {
+ if (depth == 24 || depth == 32) {
+ bg_pixel = (bg_red << RShift) |
+ (bg_green << GShift) |
+ (bg_blue << BShift);
+ } else if (depth == 16) {
+ bg_pixel = (((bg_red << 8) >> RShift) & RMask) |
+ (((bg_green << 8) >> GShift) & GMask) |
+ (((bg_blue << 8) >> BShift) & BMask);
+ } else /* depth == 8 */ {
+
+ /* GRR: add 8-bit support */
+
+ }
+ XSetForeground(display, gc, bg_pixel);
+ XFillRectangle(display, window, gc, 0, 0, rpng2_info.width,
+ rpng2_info.height);
+ }
+
+/*---------------------------------------------------------------------------
+ Wait for first Expose event to do any drawing, then flush and return.
+ ---------------------------------------------------------------------------*/
+
+ do
+ XNextEvent(display, &e);
+ while (e.type != Expose || e.xexpose.count);
+
+ XFlush(display);
+
+ return 0;
+
+} /* end function rpng2_x_create_window() */
+
+
+
+
+
+static int rpng2_x_load_bg_image(void)
+{
+ uch *src;
+ char *dest;
+ uch r1, r2, g1, g2, b1, b2;
+ uch r1_inv, r2_inv, g1_inv, g2_inv, b1_inv, b2_inv;
+ int k, hmax, max;
+ int xidx, yidx, yidx_max;
+ int even_odd_vert, even_odd_horiz, even_odd;
+ int invert_gradient2 = (bg[pat].type & 0x08);
+ int invert_column;
+ int ximage_rowbytes = ximage->bytes_per_line;
+ ulg i, row;
+ ulg pixel;
+
+/*---------------------------------------------------------------------------
+ Allocate buffer for fake background image to be used with transparent
+ images; if this fails, revert to plain background color.
+ ---------------------------------------------------------------------------*/
+
+ bg_rowbytes = 3 * rpng2_info.width;
+ bg_data = (uch *)malloc(bg_rowbytes * rpng2_info.height);
+ if (!bg_data) {
+ fprintf(stderr, PROGNAME
+ ": unable to allocate memory for background image\n");
+ bg_image = 0;
+ return 1;
+ }
+
+ bgscale = (pat == 0)? 8 : bgscale_default;
+ yidx_max = bgscale - 1;
+
+/*---------------------------------------------------------------------------
+ Vertical gradients (ramps) in NxN squares, alternating direction and
+ colors (N == bgscale).
+ ---------------------------------------------------------------------------*/
+
+ if ((bg[pat].type & 0x07) == 0) {
+ uch r1_min = rgb[bg[pat].rgb1_min].r;
+ uch g1_min = rgb[bg[pat].rgb1_min].g;
+ uch b1_min = rgb[bg[pat].rgb1_min].b;
+ uch r2_min = rgb[bg[pat].rgb2_min].r;
+ uch g2_min = rgb[bg[pat].rgb2_min].g;
+ uch b2_min = rgb[bg[pat].rgb2_min].b;
+ int r1_diff = rgb[bg[pat].rgb1_max].r - r1_min;
+ int g1_diff = rgb[bg[pat].rgb1_max].g - g1_min;
+ int b1_diff = rgb[bg[pat].rgb1_max].b - b1_min;
+ int r2_diff = rgb[bg[pat].rgb2_max].r - r2_min;
+ int g2_diff = rgb[bg[pat].rgb2_max].g - g2_min;
+ int b2_diff = rgb[bg[pat].rgb2_max].b - b2_min;
+
+ for (row = 0; row < rpng2_info.height; ++row) {
+ yidx = (int)(row % bgscale);
+ even_odd_vert = (int)((row / bgscale) & 1);
+
+ r1 = r1_min + (r1_diff * yidx) / yidx_max;
+ g1 = g1_min + (g1_diff * yidx) / yidx_max;
+ b1 = b1_min + (b1_diff * yidx) / yidx_max;
+ r1_inv = r1_min + (r1_diff * (yidx_max-yidx)) / yidx_max;
+ g1_inv = g1_min + (g1_diff * (yidx_max-yidx)) / yidx_max;
+ b1_inv = b1_min + (b1_diff * (yidx_max-yidx)) / yidx_max;
+
+ r2 = r2_min + (r2_diff * yidx) / yidx_max;
+ g2 = g2_min + (g2_diff * yidx) / yidx_max;
+ b2 = b2_min + (b2_diff * yidx) / yidx_max;
+ r2_inv = r2_min + (r2_diff * (yidx_max-yidx)) / yidx_max;
+ g2_inv = g2_min + (g2_diff * (yidx_max-yidx)) / yidx_max;
+ b2_inv = b2_min + (b2_diff * (yidx_max-yidx)) / yidx_max;
+
+ dest = (char *)bg_data + row*bg_rowbytes;
+ for (i = 0; i < rpng2_info.width; ++i) {
+ even_odd_horiz = (int)((i / bgscale) & 1);
+ even_odd = even_odd_vert ^ even_odd_horiz;
+ invert_column =
+ (even_odd_horiz && (bg[pat].type & 0x10));
+ if (even_odd == 0) { /* gradient #1 */
+ if (invert_column) {
+ *dest++ = r1_inv;
+ *dest++ = g1_inv;
+ *dest++ = b1_inv;
+ } else {
+ *dest++ = r1;
+ *dest++ = g1;
+ *dest++ = b1;
+ }
+ } else { /* gradient #2 */
+ if ((invert_column && invert_gradient2) ||
+ (!invert_column && !invert_gradient2))
+ {
+ *dest++ = r2; /* not inverted or */
+ *dest++ = g2; /* doubly inverted */
+ *dest++ = b2;
+ } else {
+ *dest++ = r2_inv;
+ *dest++ = g2_inv; /* singly inverted */
+ *dest++ = b2_inv;
+ }
+ }
+ }
+ }
+
+/*---------------------------------------------------------------------------
+ Soft gradient-diamonds with scale = bgscale. Code contributed by Adam
+ M. Costello.
+ ---------------------------------------------------------------------------*/
+
+ } else if ((bg[pat].type & 0x07) == 1) {
+
+ hmax = (bgscale-1)/2; /* half the max weight of a color */
+ max = 2*hmax; /* the max weight of a color */
+
+ r1 = rgb[bg[pat].rgb1_max].r;
+ g1 = rgb[bg[pat].rgb1_max].g;
+ b1 = rgb[bg[pat].rgb1_max].b;
+ r2 = rgb[bg[pat].rgb2_max].r;
+ g2 = rgb[bg[pat].rgb2_max].g;
+ b2 = rgb[bg[pat].rgb2_max].b;
+
+ for (row = 0; row < rpng2_info.height; ++row) {
+ yidx = (int)(row % bgscale);
+ if (yidx > hmax)
+ yidx = bgscale-1 - yidx;
+ dest = (char *)bg_data + row*bg_rowbytes;
+ for (i = 0; i < rpng2_info.width; ++i) {
+ xidx = (int)(i % bgscale);
+ if (xidx > hmax)
+ xidx = bgscale-1 - xidx;
+ k = xidx + yidx;
+ *dest++ = (k*r1 + (max-k)*r2) / max;
+ *dest++ = (k*g1 + (max-k)*g2) / max;
+ *dest++ = (k*b1 + (max-k)*b2) / max;
+ }
+ }
+
+/*---------------------------------------------------------------------------
+ Radial "starburst" with azimuthal sinusoids; [eventually number of sinu-
+ soids will equal bgscale?]. This one is slow but very cool. Code con-
+ tributed by Pieter S. van der Meulen (originally in Smalltalk).
+ ---------------------------------------------------------------------------*/
+
+ } else if ((bg[pat].type & 0x07) == 2) {
+ uch ch;
+ int ii, x, y, hw, hh, grayspot;
+ double freq, rotate, saturate, gray, intensity;
+ double angle=0.0, aoffset=0.0, maxDist, dist;
+ double red=0.0, green=0.0, blue=0.0, hue, s, v, f, p, q, t;
+
+ fprintf(stderr, "%s: computing radial background...",
+ PROGNAME);
+ fflush(stderr);
+
+ hh = (int)(rpng2_info.height / 2);
+ hw = (int)(rpng2_info.width / 2);
+
+ /* variables for radial waves:
+ * aoffset: number of degrees to rotate hue [CURRENTLY NOT USED]
+ * freq: number of color beams originating from the center
+ * grayspot: size of the graying center area (anti-alias)
+ * rotate: rotation of the beams as a function of radius
+ * saturate: saturation of beams' shape azimuthally
+ */
+ angle = CLIP(angle, 0.0, 360.0);
+ grayspot = CLIP(bg[pat].bg_gray, 1, (hh + hw));
+ freq = MAX((double)bg[pat].bg_freq, 0.0);
+ saturate = (double)bg[pat].bg_bsat * 0.1;
+ rotate = (double)bg[pat].bg_brot * 0.1;
+ gray = 0.0;
+ intensity = 0.0;
+ maxDist = (double)((hw*hw) + (hh*hh));
+
+ for (row = 0; row < rpng2_info.height; ++row) {
+ y = (int)(row - hh);
+ dest = (char *)bg_data + row*bg_rowbytes;
+ for (i = 0; i < rpng2_info.width; ++i) {
+ x = (int)(i - hw);
+ angle = (x == 0)? PI_2 : atan((double)y / (double)x);
+ gray = (double)MAX(ABS(y), ABS(x)) / grayspot;
+ gray = MIN(1.0, gray);
+ dist = (double)((x*x) + (y*y)) / maxDist;
+ intensity = cos((angle+(rotate*dist*PI)) * freq) *
+ gray * saturate;
+ intensity = (MAX(MIN(intensity,1.0),-1.0) + 1.0) * 0.5;
+ hue = (angle + PI) * INV_PI_360 + aoffset;
+ s = gray * ((double)(ABS(x)+ABS(y)) / (double)(hw + hh));
+ s = MIN(MAX(s,0.0), 1.0);
+ v = MIN(MAX(intensity,0.0), 1.0);
+
+ if (s == 0.0) {
+ ch = (uch)(v * 255.0);
+ *dest++ = ch;
+ *dest++ = ch;
+ *dest++ = ch;
+ } else {
+ if ((hue < 0.0) || (hue >= 360.0))
+ hue -= (((int)(hue / 360.0)) * 360.0);
+ hue /= 60.0;
+ ii = (int)hue;
+ f = hue - (double)ii;
+ p = (1.0 - s) * v;
+ q = (1.0 - (s * f)) * v;
+ t = (1.0 - (s * (1.0 - f))) * v;
+ if (ii == 0) { red = v; green = t; blue = p; }
+ else if (ii == 1) { red = q; green = v; blue = p; }
+ else if (ii == 2) { red = p; green = v; blue = t; }
+ else if (ii == 3) { red = p; green = q; blue = v; }
+ else if (ii == 4) { red = t; green = p; blue = v; }
+ else if (ii == 5) { red = v; green = p; blue = q; }
+ *dest++ = (uch)(red * 255.0);
+ *dest++ = (uch)(green * 255.0);
+ *dest++ = (uch)(blue * 255.0);
+ }
+ }
+ }
+ fprintf(stderr, "done.\n");
+ fflush(stderr);
+ }
+
+/*---------------------------------------------------------------------------
+ Blast background image to display buffer before beginning PNG decode.
+ ---------------------------------------------------------------------------*/
+
+ if (depth == 24 || depth == 32) {
+ ulg red, green, blue;
+ int bpp = ximage->bits_per_pixel;
+
+ for (row = 0; row < rpng2_info.height; ++row) {
+ src = bg_data + row*bg_rowbytes;
+ dest = ximage->data + row*ximage_rowbytes;
+ if (bpp == 32) { /* slightly optimized version */
+ for (i = rpng2_info.width; i > 0; --i) {
+ red = *src++;
+ green = *src++;
+ blue = *src++;
+ pixel = (red << RShift) |
+ (green << GShift) |
+ (blue << BShift);
+ /* recall that we set ximage->byte_order = MSBFirst above */
+ *dest++ = (char)((pixel >> 24) & 0xff);
+ *dest++ = (char)((pixel >> 16) & 0xff);
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ }
+ } else {
+ for (i = rpng2_info.width; i > 0; --i) {
+ red = *src++;
+ green = *src++;
+ blue = *src++;
+ pixel = (red << RShift) |
+ (green << GShift) |
+ (blue << BShift);
+ /* recall that we set ximage->byte_order = MSBFirst above */
+ /* GRR BUG? this assumes bpp == 24 & bits are packed low */
+ /* (probably need to use RShift, RMask, etc.) */
+ *dest++ = (char)((pixel >> 16) & 0xff);
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ }
+ }
+ }
+
+ } else if (depth == 16) {
+ ush red, green, blue;
+
+ for (row = 0; row < rpng2_info.height; ++row) {
+ src = bg_data + row*bg_rowbytes;
+ dest = ximage->data + row*ximage_rowbytes;
+ for (i = rpng2_info.width; i > 0; --i) {
+ red = ((ush)(*src) << 8); ++src;
+ green = ((ush)(*src) << 8); ++src;
+ blue = ((ush)(*src) << 8); ++src;
+ pixel = ((red >> RShift) & RMask) |
+ ((green >> GShift) & GMask) |
+ ((blue >> BShift) & BMask);
+ /* recall that we set ximage->byte_order = MSBFirst above */
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ }
+ }
+
+ } else /* depth == 8 */ {
+
+ /* GRR: add 8-bit support */
+
+ }
+
+ XPutImage(display, window, gc, ximage, 0, 0, 0, 0, rpng2_info.width,
+ rpng2_info.height);
+
+ return 0;
+
+} /* end function rpng2_x_load_bg_image() */
+
+
+
+
+
+static void rpng2_x_display_row(ulg row)
+{
+ uch bg_red = rpng2_info.bg_red;
+ uch bg_green = rpng2_info.bg_green;
+ uch bg_blue = rpng2_info.bg_blue;
+ uch *src, *src2=NULL;
+ char *dest;
+ uch r, g, b, a;
+ int ximage_rowbytes = ximage->bytes_per_line;
+ ulg i, pixel;
+ static int rows=0, prevpass=(-1);
+ static ulg firstrow;
+
+/*---------------------------------------------------------------------------
+ rows and firstrow simply track how many rows (and which ones) have not
+ yet been displayed; alternatively, we could call XPutImage() for every
+ row and not bother with the records-keeping.
+ ---------------------------------------------------------------------------*/
+
+ Trace((stderr, "beginning rpng2_x_display_row()\n"))
+
+ if (rpng2_info.pass != prevpass) {
+ if (pause_after_pass && rpng2_info.pass > 0) {
+ XEvent e;
+ KeySym k;
+
+ fprintf(stderr,
+ "%s: end of pass %d of 7; click in image window to continue\n",
+ PROGNAME, prevpass + 1);
+ do
+ XNextEvent(display, &e);
+ while (!QUIT(e,k));
+ }
+ fprintf(stderr, "%s: pass %d of 7\r", PROGNAME, rpng2_info.pass + 1);
+ fflush(stderr);
+ prevpass = rpng2_info.pass;
+ }
+
+ if (rows == 0)
+ firstrow = row; /* first row that is not yet displayed */
+
+ ++rows; /* count of rows received but not yet displayed */
+
+/*---------------------------------------------------------------------------
+ Aside from the use of the rpng2_info struct, the lack of an outer loop
+ (over rows) and moving the XPutImage() call outside the "if (depth)"
+ tests, this routine is identical to rpng_x_display_image() in the non-
+ progressive version of the program.
+ ---------------------------------------------------------------------------*/
+
+ if (depth == 24 || depth == 32) {
+ ulg red, green, blue;
+ int bpp = ximage->bits_per_pixel;
+
+ src = rpng2_info.image_data + row*rpng2_info.rowbytes;
+ if (bg_image)
+ src2 = bg_data + row*bg_rowbytes;
+ dest = ximage->data + row*ximage_rowbytes;
+ if (rpng2_info.channels == 3) {
+ for (i = rpng2_info.width; i > 0; --i) {
+ red = *src++;
+ green = *src++;
+ blue = *src++;
+ pixel = (red << RShift) |
+ (green << GShift) |
+ (blue << BShift);
+ /* recall that we set ximage->byte_order = MSBFirst above */
+ if (bpp == 32) {
+ *dest++ = (char)((pixel >> 24) & 0xff);
+ *dest++ = (char)((pixel >> 16) & 0xff);
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ } else {
+ /* GRR BUG? this assumes bpp == 24 & bits are packed low */
+ /* (probably need to use RShift, RMask, etc.) */
+ *dest++ = (char)((pixel >> 16) & 0xff);
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ }
+ }
+ } else /* if (rpng2_info.channels == 4) */ {
+ for (i = rpng2_info.width; i > 0; --i) {
+ r = *src++;
+ g = *src++;
+ b = *src++;
+ a = *src++;
+ if (bg_image) {
+ bg_red = *src2++;
+ bg_green = *src2++;
+ bg_blue = *src2++;
+ }
+ if (a == 255) {
+ red = r;
+ green = g;
+ blue = b;
+ } else if (a == 0) {
+ red = bg_red;
+ green = bg_green;
+ blue = bg_blue;
+ } else {
+ /* this macro (from png.h) composites the foreground
+ * and background values and puts the result into the
+ * first argument */
+ alpha_composite(red, r, a, bg_red);
+ alpha_composite(green, g, a, bg_green);
+ alpha_composite(blue, b, a, bg_blue);
+ }
+ pixel = (red << RShift) |
+ (green << GShift) |
+ (blue << BShift);
+ /* recall that we set ximage->byte_order = MSBFirst above */
+ if (bpp == 32) {
+ *dest++ = (char)((pixel >> 24) & 0xff);
+ *dest++ = (char)((pixel >> 16) & 0xff);
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ } else {
+ /* GRR BUG? this assumes bpp == 24 & bits are packed low */
+ /* (probably need to use RShift, RMask, etc.) */
+ *dest++ = (char)((pixel >> 16) & 0xff);
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ }
+ }
+ }
+
+ } else if (depth == 16) {
+ ush red, green, blue;
+
+ src = rpng2_info.row_pointers[row];
+ if (bg_image)
+ src2 = bg_data + row*bg_rowbytes;
+ dest = ximage->data + row*ximage_rowbytes;
+ if (rpng2_info.channels == 3) {
+ for (i = rpng2_info.width; i > 0; --i) {
+ red = ((ush)(*src) << 8);
+ ++src;
+ green = ((ush)(*src) << 8);
+ ++src;
+ blue = ((ush)(*src) << 8);
+ ++src;
+ pixel = ((red >> RShift) & RMask) |
+ ((green >> GShift) & GMask) |
+ ((blue >> BShift) & BMask);
+ /* recall that we set ximage->byte_order = MSBFirst above */
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ }
+ } else /* if (rpng2_info.channels == 4) */ {
+ for (i = rpng2_info.width; i > 0; --i) {
+ r = *src++;
+ g = *src++;
+ b = *src++;
+ a = *src++;
+ if (bg_image) {
+ bg_red = *src2++;
+ bg_green = *src2++;
+ bg_blue = *src2++;
+ }
+ if (a == 255) {
+ red = ((ush)r << 8);
+ green = ((ush)g << 8);
+ blue = ((ush)b << 8);
+ } else if (a == 0) {
+ red = ((ush)bg_red << 8);
+ green = ((ush)bg_green << 8);
+ blue = ((ush)bg_blue << 8);
+ } else {
+ /* this macro (from png.h) composites the foreground
+ * and background values and puts the result back into
+ * the first argument (== fg byte here: safe) */
+ alpha_composite(r, r, a, bg_red);
+ alpha_composite(g, g, a, bg_green);
+ alpha_composite(b, b, a, bg_blue);
+ red = ((ush)r << 8);
+ green = ((ush)g << 8);
+ blue = ((ush)b << 8);
+ }
+ pixel = ((red >> RShift) & RMask) |
+ ((green >> GShift) & GMask) |
+ ((blue >> BShift) & BMask);
+ /* recall that we set ximage->byte_order = MSBFirst above */
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ }
+ }
+
+ } else /* depth == 8 */ {
+
+ /* GRR: add 8-bit support */
+
+ }
+
+
+/*---------------------------------------------------------------------------
+ Display after every 16 rows or when on one of last two rows. (Region
+ may include previously displayed lines due to interlacing--i.e., not
+ contiguous. Also, second-to-last row is final one in interlaced images
+ with odd number of rows.) For demos, flush (and delay) after every 16th
+ row so "sparse" passes don't go twice as fast.
+ ---------------------------------------------------------------------------*/
+
+ if (demo_timing && (row - firstrow >= 16 || row >= rpng2_info.height-2)) {
+ XPutImage(display, window, gc, ximage, 0, (int)firstrow, 0,
+ (int)firstrow, rpng2_info.width, row - firstrow + 1);
+ XFlush(display);
+ rows = 0;
+ usleep(usleep_duration);
+ } else
+ if (!demo_timing && ((rows & 0xf) == 0 || row >= rpng2_info.height-2)) {
+ XPutImage(display, window, gc, ximage, 0, (int)firstrow, 0,
+ (int)firstrow, rpng2_info.width, row - firstrow + 1);
+ XFlush(display);
+ rows = 0;
+ }
+
+}
+
+
+
+
+
+static void rpng2_x_finish_display(void)
+{
+ Trace((stderr, "beginning rpng2_x_finish_display()\n"))
+
+ /* last row has already been displayed by rpng2_x_display_row(), so we
+ * have nothing to do here except set a flag and let the user know that
+ * the image is done */
+
+ rpng2_info.state = kDone;
+ printf(
+ "Done. Press Q, Esc or mouse button 1 (within image window) to quit.\n");
+ fflush(stdout);
+}
+
+
+
+
+
+static void rpng2_x_redisplay_image(ulg startcol, ulg startrow,
+ ulg width, ulg height)
+{
+ uch bg_red = rpng2_info.bg_red;
+ uch bg_green = rpng2_info.bg_green;
+ uch bg_blue = rpng2_info.bg_blue;
+ uch *src, *src2=NULL;
+ char *dest;
+ uch r, g, b, a;
+ ulg i, row, lastrow = 0;
+ ulg pixel;
+ int ximage_rowbytes = ximage->bytes_per_line;
+
+
+ Trace((stderr, "beginning display loop (image_channels == %d)\n",
+ rpng2_info.channels))
+ Trace((stderr, " (width = %ld, rowbytes = %d, ximage_rowbytes = %d)\n",
+ rpng2_info.width, rpng2_info.rowbytes, ximage_rowbytes))
+ Trace((stderr, " (bpp = %d)\n", ximage->bits_per_pixel))
+ Trace((stderr, " (byte_order = %s)\n", ximage->byte_order == MSBFirst?
+ "MSBFirst" : (ximage->byte_order == LSBFirst? "LSBFirst" : "unknown")))
+
+/*---------------------------------------------------------------------------
+ Aside from the use of the rpng2_info struct and of src2 (for background
+ image), this routine is identical to rpng_x_display_image() in the non-
+ progressive version of the program--for the simple reason that redisplay
+ of the image against a new background happens after the image is fully
+ decoded and therefore is, by definition, non-progressive.
+ ---------------------------------------------------------------------------*/
+
+ if (depth == 24 || depth == 32) {
+ ulg red, green, blue;
+ int bpp = ximage->bits_per_pixel;
+
+ for (lastrow = row = startrow; row < startrow+height; ++row) {
+ src = rpng2_info.image_data + row*rpng2_info.rowbytes;
+ if (bg_image)
+ src2 = bg_data + row*bg_rowbytes;
+ dest = ximage->data + row*ximage_rowbytes;
+ if (rpng2_info.channels == 3) {
+ for (i = rpng2_info.width; i > 0; --i) {
+ red = *src++;
+ green = *src++;
+ blue = *src++;
+#ifdef NO_24BIT_MASKS
+ pixel = (red << RShift) |
+ (green << GShift) |
+ (blue << BShift);
+ /* recall that we set ximage->byte_order = MSBFirst above */
+ if (bpp == 32) {
+ *dest++ = (char)((pixel >> 24) & 0xff);
+ *dest++ = (char)((pixel >> 16) & 0xff);
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ } else {
+ /* this assumes bpp == 24 & bits are packed low */
+ /* (probably need to use RShift, RMask, etc.) */
+ *dest++ = (char)((pixel >> 16) & 0xff);
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ }
+#else
+ red = (RShift < 0)? red << (-RShift) : red >> RShift;
+ green = (GShift < 0)? green << (-GShift) : green >> GShift;
+ blue = (BShift < 0)? blue << (-BShift) : blue >> BShift;
+ pixel = (red & RMask) | (green & GMask) | (blue & BMask);
+ /* recall that we set ximage->byte_order = MSBFirst above */
+ if (bpp == 32) {
+ *dest++ = (char)((pixel >> 24) & 0xff);
+ *dest++ = (char)((pixel >> 16) & 0xff);
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ } else {
+ /* GRR BUG */
+ /* this assumes bpp == 24 & bits are packed low */
+ /* (probably need to use RShift/RMask/etc. here, too) */
+ *dest++ = (char)((pixel >> 16) & 0xff);
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ }
+#endif
+ }
+
+ } else /* if (rpng2_info.channels == 4) */ {
+ for (i = rpng2_info.width; i > 0; --i) {
+ r = *src++;
+ g = *src++;
+ b = *src++;
+ a = *src++;
+ if (bg_image) {
+ bg_red = *src2++;
+ bg_green = *src2++;
+ bg_blue = *src2++;
+ }
+ if (a == 255) {
+ red = r;
+ green = g;
+ blue = b;
+ } else if (a == 0) {
+ red = bg_red;
+ green = bg_green;
+ blue = bg_blue;
+ } else {
+ /* this macro (from png.h) composites the foreground
+ * and background values and puts the result into the
+ * first argument */
+ alpha_composite(red, r, a, bg_red);
+ alpha_composite(green, g, a, bg_green);
+ alpha_composite(blue, b, a, bg_blue);
+ }
+#ifdef NO_24BIT_MASKS
+ pixel = (red << RShift) |
+ (green << GShift) |
+ (blue << BShift);
+ /* recall that we set ximage->byte_order = MSBFirst above */
+ if (bpp == 32) {
+ *dest++ = (char)((pixel >> 24) & 0xff);
+ *dest++ = (char)((pixel >> 16) & 0xff);
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ } else {
+ /* this assumes bpp == 24 & bits are packed low */
+ /* (probably need to use RShift, RMask, etc.) */
+ *dest++ = (char)((pixel >> 16) & 0xff);
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ }
+#else
+ red = (RShift < 0)? red << (-RShift) : red >> RShift;
+ green = (GShift < 0)? green << (-GShift) : green >> GShift;
+ blue = (BShift < 0)? blue << (-BShift) : blue >> BShift;
+ pixel = (red & RMask) | (green & GMask) | (blue & BMask);
+ /* recall that we set ximage->byte_order = MSBFirst above */
+ if (bpp == 32) {
+ *dest++ = (char)((pixel >> 24) & 0xff);
+ *dest++ = (char)((pixel >> 16) & 0xff);
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ } else {
+ /* GRR BUG */
+ /* this assumes bpp == 24 & bits are packed low */
+ /* (probably need to use RShift/RMask/etc. here, too) */
+ *dest++ = (char)((pixel >> 16) & 0xff);
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ }
+#endif
+ }
+ }
+ /* display after every 16 lines */
+ if (((row+1) & 0xf) == 0) {
+ XPutImage(display, window, gc, ximage, 0, (int)lastrow, 0,
+ (int)lastrow, rpng2_info.width, 16);
+ XFlush(display);
+ lastrow = row + 1;
+ }
+ }
+
+ } else if (depth == 16) {
+ ush red, green, blue;
+
+ for (lastrow = row = startrow; row < startrow+height; ++row) {
+ src = rpng2_info.row_pointers[row];
+ if (bg_image)
+ src2 = bg_data + row*bg_rowbytes;
+ dest = ximage->data + row*ximage_rowbytes;
+ if (rpng2_info.channels == 3) {
+ for (i = rpng2_info.width; i > 0; --i) {
+ red = ((ush)(*src) << 8);
+ ++src;
+ green = ((ush)(*src) << 8);
+ ++src;
+ blue = ((ush)(*src) << 8);
+ ++src;
+ pixel = ((red >> RShift) & RMask) |
+ ((green >> GShift) & GMask) |
+ ((blue >> BShift) & BMask);
+ /* recall that we set ximage->byte_order = MSBFirst above */
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ }
+ } else /* if (rpng2_info.channels == 4) */ {
+ for (i = rpng2_info.width; i > 0; --i) {
+ r = *src++;
+ g = *src++;
+ b = *src++;
+ a = *src++;
+ if (bg_image) {
+ bg_red = *src2++;
+ bg_green = *src2++;
+ bg_blue = *src2++;
+ }
+ if (a == 255) {
+ red = ((ush)r << 8);
+ green = ((ush)g << 8);
+ blue = ((ush)b << 8);
+ } else if (a == 0) {
+ red = ((ush)bg_red << 8);
+ green = ((ush)bg_green << 8);
+ blue = ((ush)bg_blue << 8);
+ } else {
+ /* this macro (from png.h) composites the foreground
+ * and background values and puts the result back into
+ * the first argument (== fg byte here: safe) */
+ alpha_composite(r, r, a, bg_red);
+ alpha_composite(g, g, a, bg_green);
+ alpha_composite(b, b, a, bg_blue);
+ red = ((ush)r << 8);
+ green = ((ush)g << 8);
+ blue = ((ush)b << 8);
+ }
+ pixel = ((red >> RShift) & RMask) |
+ ((green >> GShift) & GMask) |
+ ((blue >> BShift) & BMask);
+ /* recall that we set ximage->byte_order = MSBFirst above */
+ *dest++ = (char)((pixel >> 8) & 0xff);
+ *dest++ = (char)( pixel & 0xff);
+ }
+ }
+ /* display after every 16 lines */
+ if (((row+1) & 0xf) == 0) {
+ XPutImage(display, window, gc, ximage, 0, (int)lastrow, 0,
+ (int)lastrow, rpng2_info.width, 16);
+ XFlush(display);
+ lastrow = row + 1;
+ }
+ }
+
+ } else /* depth == 8 */ {
+
+ /* GRR: add 8-bit support */
+
+ }
+
+ Trace((stderr, "calling final XPutImage()\n"))
+ if (lastrow < startrow+height) {
+ XPutImage(display, window, gc, ximage, 0, (int)lastrow, 0,
+ (int)lastrow, rpng2_info.width, rpng2_info.height-lastrow);
+ XFlush(display);
+ }
+
+ (void)startcol;
+ (void)width;
+
+} /* end function rpng2_x_redisplay_image() */
+
+
+
+
+
+#ifdef FEATURE_LOOP
+
+static void rpng2_x_reload_bg_image(void)
+{
+ char *dest;
+ uch r1, r2, g1, g2, b1, b2;
+ uch r1_inv, r2_inv, g1_inv, g2_inv, b1_inv, b2_inv;
+ int k, hmax, max;
+ int xidx, yidx, yidx_max;
+ int even_odd_vert, even_odd_horiz, even_odd;
+ int invert_gradient2 = (bg[pat].type & 0x08);
+ int invert_column;
+ ulg i, row;
+
+
+ bgscale = (pat == 0)? 8 : bgscale_default;
+ yidx_max = bgscale - 1;
+
+/*---------------------------------------------------------------------------
+ Vertical gradients (ramps) in NxN squares, alternating direction and
+ colors (N == bgscale).
+ ---------------------------------------------------------------------------*/
+
+ if ((bg[pat].type & 0x07) == 0) {
+ uch r1_min = rgb[bg[pat].rgb1_min].r;
+ uch g1_min = rgb[bg[pat].rgb1_min].g;
+ uch b1_min = rgb[bg[pat].rgb1_min].b;
+ uch r2_min = rgb[bg[pat].rgb2_min].r;
+ uch g2_min = rgb[bg[pat].rgb2_min].g;
+ uch b2_min = rgb[bg[pat].rgb2_min].b;
+ int r1_diff = rgb[bg[pat].rgb1_max].r - r1_min;
+ int g1_diff = rgb[bg[pat].rgb1_max].g - g1_min;
+ int b1_diff = rgb[bg[pat].rgb1_max].b - b1_min;
+ int r2_diff = rgb[bg[pat].rgb2_max].r - r2_min;
+ int g2_diff = rgb[bg[pat].rgb2_max].g - g2_min;
+ int b2_diff = rgb[bg[pat].rgb2_max].b - b2_min;
+
+ for (row = 0; row < rpng2_info.height; ++row) {
+ yidx = (int)(row % bgscale);
+ even_odd_vert = (int)((row / bgscale) & 1);
+
+ r1 = r1_min + (r1_diff * yidx) / yidx_max;
+ g1 = g1_min + (g1_diff * yidx) / yidx_max;
+ b1 = b1_min + (b1_diff * yidx) / yidx_max;
+ r1_inv = r1_min + (r1_diff * (yidx_max-yidx)) / yidx_max;
+ g1_inv = g1_min + (g1_diff * (yidx_max-yidx)) / yidx_max;
+ b1_inv = b1_min + (b1_diff * (yidx_max-yidx)) / yidx_max;
+
+ r2 = r2_min + (r2_diff * yidx) / yidx_max;
+ g2 = g2_min + (g2_diff * yidx) / yidx_max;
+ b2 = b2_min + (b2_diff * yidx) / yidx_max;
+ r2_inv = r2_min + (r2_diff * (yidx_max-yidx)) / yidx_max;
+ g2_inv = g2_min + (g2_diff * (yidx_max-yidx)) / yidx_max;
+ b2_inv = b2_min + (b2_diff * (yidx_max-yidx)) / yidx_max;
+
+ dest = (char *)bg_data + row*bg_rowbytes;
+ for (i = 0; i < rpng2_info.width; ++i) {
+ even_odd_horiz = (int)((i / bgscale) & 1);
+ even_odd = even_odd_vert ^ even_odd_horiz;
+ invert_column =
+ (even_odd_horiz && (bg[pat].type & 0x10));
+ if (even_odd == 0) { /* gradient #1 */
+ if (invert_column) {
+ *dest++ = r1_inv;
+ *dest++ = g1_inv;
+ *dest++ = b1_inv;
+ } else {
+ *dest++ = r1;
+ *dest++ = g1;
+ *dest++ = b1;
+ }
+ } else { /* gradient #2 */
+ if ((invert_column && invert_gradient2) ||
+ (!invert_column && !invert_gradient2))
+ {
+ *dest++ = r2; /* not inverted or */
+ *dest++ = g2; /* doubly inverted */
+ *dest++ = b2;
+ } else {
+ *dest++ = r2_inv;
+ *dest++ = g2_inv; /* singly inverted */
+ *dest++ = b2_inv;
+ }
+ }
+ }
+ }
+
+/*---------------------------------------------------------------------------
+ Soft gradient-diamonds with scale = bgscale. Code contributed by Adam
+ M. Costello.
+ ---------------------------------------------------------------------------*/
+
+ } else if ((bg[pat].type & 0x07) == 1) {
+
+ hmax = (bgscale-1)/2; /* half the max weight of a color */
+ max = 2*hmax; /* the max weight of a color */
+
+ r1 = rgb[bg[pat].rgb1_max].r;
+ g1 = rgb[bg[pat].rgb1_max].g;
+ b1 = rgb[bg[pat].rgb1_max].b;
+ r2 = rgb[bg[pat].rgb2_max].r;
+ g2 = rgb[bg[pat].rgb2_max].g;
+ b2 = rgb[bg[pat].rgb2_max].b;
+
+ for (row = 0; row < rpng2_info.height; ++row) {
+ yidx = (int)(row % bgscale);
+ if (yidx > hmax)
+ yidx = bgscale-1 - yidx;
+ dest = (char *)bg_data + row*bg_rowbytes;
+ for (i = 0; i < rpng2_info.width; ++i) {
+ xidx = (int)(i % bgscale);
+ if (xidx > hmax)
+ xidx = bgscale-1 - xidx;
+ k = xidx + yidx;
+ *dest++ = (k*r1 + (max-k)*r2) / max;
+ *dest++ = (k*g1 + (max-k)*g2) / max;
+ *dest++ = (k*b1 + (max-k)*b2) / max;
+ }
+ }
+
+/*---------------------------------------------------------------------------
+ Radial "starburst" with azimuthal sinusoids; [eventually number of sinu-
+ soids will equal bgscale?]. This one is slow but very cool. Code con-
+ tributed by Pieter S. van der Meulen (originally in Smalltalk).
+ ---------------------------------------------------------------------------*/
+
+ } else if ((bg[pat].type & 0x07) == 2) {
+ uch ch;
+ int ii, x, y, hw, hh, grayspot;
+ double freq, rotate, saturate, gray, intensity;
+ double angle=0.0, aoffset=0.0, maxDist, dist;
+ double red=0.0, green=0.0, blue=0.0, hue, s, v, f, p, q, t;
+
+ hh = (int)(rpng2_info.height / 2);
+ hw = (int)(rpng2_info.width / 2);
+
+ /* variables for radial waves:
+ * aoffset: number of degrees to rotate hue [CURRENTLY NOT USED]
+ * freq: number of color beams originating from the center
+ * grayspot: size of the graying center area (anti-alias)
+ * rotate: rotation of the beams as a function of radius
+ * saturate: saturation of beams' shape azimuthally
+ */
+ angle = CLIP(angle, 0.0, 360.0);
+ grayspot = CLIP(bg[pat].bg_gray, 1, (hh + hw));
+ freq = MAX((double)bg[pat].bg_freq, 0.0);
+ saturate = (double)bg[pat].bg_bsat * 0.1;
+ rotate = (double)bg[pat].bg_brot * 0.1;
+ gray = 0.0;
+ intensity = 0.0;
+ maxDist = (double)((hw*hw) + (hh*hh));
+
+ for (row = 0; row < rpng2_info.height; ++row) {
+ y = (int)(row - hh);
+ dest = (char *)bg_data + row*bg_rowbytes;
+ for (i = 0; i < rpng2_info.width; ++i) {
+ x = (int)(i - hw);
+ angle = (x == 0)? PI_2 : atan((double)y / (double)x);
+ gray = (double)MAX(ABS(y), ABS(x)) / grayspot;
+ gray = MIN(1.0, gray);
+ dist = (double)((x*x) + (y*y)) / maxDist;
+ intensity = cos((angle+(rotate*dist*PI)) * freq) *
+ gray * saturate;
+ intensity = (MAX(MIN(intensity,1.0),-1.0) + 1.0) * 0.5;
+ hue = (angle + PI) * INV_PI_360 + aoffset;
+ s = gray * ((double)(ABS(x)+ABS(y)) / (double)(hw + hh));
+ s = MIN(MAX(s,0.0), 1.0);
+ v = MIN(MAX(intensity,0.0), 1.0);
+
+ if (s == 0.0) {
+ ch = (uch)(v * 255.0);
+ *dest++ = ch;
+ *dest++ = ch;
+ *dest++ = ch;
+ } else {
+ if ((hue < 0.0) || (hue >= 360.0))
+ hue -= (((int)(hue / 360.0)) * 360.0);
+ hue /= 60.0;
+ ii = (int)hue;
+ f = hue - (double)ii;
+ p = (1.0 - s) * v;
+ q = (1.0 - (s * f)) * v;
+ t = (1.0 - (s * (1.0 - f))) * v;
+ if (ii == 0) { red = v; green = t; blue = p; }
+ else if (ii == 1) { red = q; green = v; blue = p; }
+ else if (ii == 2) { red = p; green = v; blue = t; }
+ else if (ii == 3) { red = p; green = q; blue = v; }
+ else if (ii == 4) { red = t; green = p; blue = v; }
+ else if (ii == 5) { red = v; green = p; blue = q; }
+ *dest++ = (uch)(red * 255.0);
+ *dest++ = (uch)(green * 255.0);
+ *dest++ = (uch)(blue * 255.0);
+ }
+ }
+ }
+ }
+
+} /* end function rpng2_x_reload_bg_image() */
+
+
+
+
+
+static int is_number(char *p)
+{
+ while (*p) {
+ if (!isdigit(*p))
+ return FALSE;
+ ++p;
+ }
+ return TRUE;
+}
+
+#endif /* FEATURE_LOOP */
+
+
+
+
+
+static void rpng2_x_cleanup(void)
+{
+ if (bg_image && bg_data) {
+ free(bg_data);
+ bg_data = NULL;
+ }
+
+ if (rpng2_info.image_data) {
+ free(rpng2_info.image_data);
+ rpng2_info.image_data = NULL;
+ }
+
+ if (rpng2_info.row_pointers) {
+ free(rpng2_info.row_pointers);
+ rpng2_info.row_pointers = NULL;
+ }
+
+ if (ximage) {
+ if (ximage->data) {
+ free(ximage->data); /* we allocated it, so we free it */
+ ximage->data = (char *)NULL; /* instead of XDestroyImage() */
+ }
+ XDestroyImage(ximage);
+ ximage = NULL;
+ }
+
+ if (have_gc)
+ XFreeGC(display, gc);
+
+ if (have_window)
+ XDestroyWindow(display, window);
+
+ if (have_colormap)
+ XFreeColormap(display, colormap);
+
+ if (have_nondefault_visual)
+ XFree(visual_list);
+}
+
+
+
+
+
+static int rpng2_x_msb(ulg u32val)
+{
+ int i;
+
+ for (i = 31; i >= 0; --i) {
+ if (u32val & 0x80000000L)
+ break;
+ u32val <<= 1;
+ }
+ return i;
+}
diff --git a/libpng/contrib/gregbook/toucan.png b/libpng/contrib/gregbook/toucan.png
new file mode 100644
index 0000000..03960d4
--- /dev/null
+++ b/libpng/contrib/gregbook/toucan.png
Binary files differ
diff --git a/libpng/contrib/gregbook/wpng.c b/libpng/contrib/gregbook/wpng.c
new file mode 100644
index 0000000..a06e352
--- /dev/null
+++ b/libpng/contrib/gregbook/wpng.c
@@ -0,0 +1,853 @@
+/*---------------------------------------------------------------------------
+
+ wpng - simple PNG-writing program wpng.c
+
+ This program converts certain NetPBM binary files (grayscale and RGB,
+ maxval = 255) to PNG. Non-interlaced PNGs are written progressively;
+ interlaced PNGs are read and written in one memory-intensive blast.
+
+ Thanks to Jean-loup Gailly for providing the necessary trick to read
+ interactive text from the keyboard while stdin is redirected. Thanks
+ to Cosmin Truta for Cygwin fixes.
+
+ NOTE: includes provisional support for PNM type "8" (portable alphamap)
+ images, presumed to be a 32-bit interleaved RGBA format; no pro-
+ vision for possible interleaved grayscale+alpha (16-bit) format.
+ THIS IS UNLIKELY TO BECOME AN OFFICIAL NETPBM ALPHA FORMAT!
+
+ to do:
+ - delete output file if quit before calling any writepng routines
+ - process backspace with -text option under DOS/Win? (currently get ^H)
+
+ ---------------------------------------------------------------------------
+
+ Changelog:
+ - 1.01: initial public release
+ - 1.02: modified to allow abbreviated options
+ - 1.03: removed extraneous character from usage screen; fixed bug in
+ command-line parsing
+ - 1.04: fixed DOS/OS2/Win32 detection, including partial Cygwin fix
+ (see http://home.att.net/~perlspinr/diffs/GregBook_cygwin.diff)
+ - 2.00: dual-licensed (added GNU GPL)
+
+ [REPORTED BUG (win32 only): "contrib/gregbook/wpng.c - cmd line
+ dose not work! In order to do something useful I needed to redirect
+ both input and output, with cygwin and with bcc32 as well. Under
+ Linux, the same wpng appears to work fine. I don't know what is
+ the problem."]
+
+ ---------------------------------------------------------------------------
+
+ Copyright (c) 1998-2007 Greg Roelofs. All rights reserved.
+
+ This software is provided "as is," without warranty of any kind,
+ express or implied. In no event shall the author or contributors
+ be held liable for any damages arising in any way from the use of
+ this software.
+
+ The contents of this file are DUAL-LICENSED. You may modify and/or
+ redistribute this software according to the terms of one of the
+ following two licenses (at your option):
+
+
+ LICENSE 1 ("BSD-like with advertising clause"):
+
+ Permission is granted to anyone to use this software for any purpose,
+ including commercial applications, and to alter it and redistribute
+ it freely, subject to the following restrictions:
+
+ 1. Redistributions of source code must retain the above copyright
+ notice, disclaimer, and this list of conditions.
+ 2. Redistributions in binary form must reproduce the above copyright
+ notice, disclaimer, and this list of conditions in the documenta-
+ tion and/or other materials provided with the distribution.
+ 3. All advertising materials mentioning features or use of this
+ software must display the following acknowledgment:
+
+ This product includes software developed by Greg Roelofs
+ and contributors for the book, "PNG: The Definitive Guide,"
+ published by O'Reilly and Associates.
+
+
+ LICENSE 2 (GNU GPL v2 or later):
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ ---------------------------------------------------------------------------*/
+
+#define PROGNAME "wpng"
+#define VERSION "2.00 of 2 June 2007"
+#define APPNAME "Simple PGM/PPM/PAM to PNG Converter"
+
+#if defined(__MSDOS__) || defined(__OS2__)
+# define DOS_OS2_W32
+#elif defined(WIN32) || defined(_WIN32) || defined(__WIN32__)
+# ifndef __GNUC__ /* treat Win32 native ports of gcc as Unix environments */
+# define DOS_OS2_W32
+# endif
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <setjmp.h> /* for jmpbuf declaration in writepng.h */
+#include <time.h>
+
+#ifdef DOS_OS2_W32
+# include <io.h> /* for isatty(), setmode() prototypes */
+# include <fcntl.h> /* O_BINARY for fdopen() without text translation */
+# ifdef __EMX__
+# ifndef getch
+# define getch() _read_kbd(0, 1, 0) /* need getche() */
+# endif
+# else /* !__EMX__ */
+# ifdef __GO32__
+# include <pc.h>
+# define getch() getkey() /* GRR: need getche() */
+# else
+# include <conio.h> /* for getche() console input */
+# endif
+# endif /* ?__EMX__ */
+# define FGETS(buf,len,stream) dos_kbd_gets(buf,len)
+#else
+# include <unistd.h> /* for isatty() prototype */
+# define FGETS fgets
+#endif
+
+/* #define DEBUG : this enables the Trace() macros */
+
+/* #define FORBID_LATIN1_CTRL : this requires the user to re-enter any
+ text that includes control characters discouraged by the PNG spec; text
+ that includes an escape character (27) must be re-entered regardless */
+
+#include "writepng.h" /* typedefs, common macros, writepng prototypes */
+
+
+
+/* local prototypes */
+
+static int wpng_isvalid_latin1(uch *p, int len);
+static void wpng_cleanup(void);
+
+#ifdef DOS_OS2_W32
+ static char *dos_kbd_gets(char *buf, int len);
+#endif
+
+
+
+static mainprog_info wpng_info; /* lone global */
+
+
+
+int main(int argc, char **argv)
+{
+#ifndef DOS_OS2_W32
+ FILE *keybd;
+#endif
+#ifdef sgi
+ FILE *tmpfile; /* or we could just use keybd, since no overlap */
+ char tmpline[80];
+#endif
+ char *inname = NULL, outname[256];
+ char *p, pnmchar, pnmline[256];
+ char *bgstr, *textbuf = NULL;
+ ulg rowbytes;
+ int rc, len = 0;
+ int error = 0;
+ int text = FALSE;
+ int maxval;
+ double LUT_exponent; /* just the lookup table */
+ double CRT_exponent = 2.2; /* just the monitor */
+ double default_display_exponent; /* whole display system */
+ double default_gamma = 0.0;
+
+
+ wpng_info.infile = NULL;
+ wpng_info.outfile = NULL;
+ wpng_info.image_data = NULL;
+ wpng_info.row_pointers = NULL;
+ wpng_info.filter = FALSE;
+ wpng_info.interlaced = FALSE;
+ wpng_info.have_bg = FALSE;
+ wpng_info.have_time = FALSE;
+ wpng_info.have_text = 0;
+ wpng_info.gamma = 0.0;
+
+
+ /* First get the default value for our display-system exponent, i.e.,
+ * the product of the CRT exponent and the exponent corresponding to
+ * the frame-buffer's lookup table (LUT), if any. If the PNM image
+ * looks correct on the user's display system, its file gamma is the
+ * inverse of this value. (Note that this is not an exhaustive list
+ * of LUT values--e.g., OpenStep has a lot of weird ones--but it should
+ * cover 99% of the current possibilities. This section must ensure
+ * that default_display_exponent is positive.) */
+
+#if defined(NeXT)
+ /* third-party utilities can modify the default LUT exponent */
+ LUT_exponent = 1.0 / 2.2;
+ /*
+ if (some_next_function_that_returns_gamma(&next_gamma))
+ LUT_exponent = 1.0 / next_gamma;
+ */
+#elif defined(sgi)
+ LUT_exponent = 1.0 / 1.7;
+ /* there doesn't seem to be any documented function to
+ * get the "gamma" value, so we do it the hard way */
+ tmpfile = fopen("/etc/config/system.glGammaVal", "r");
+ if (tmpfile) {
+ double sgi_gamma;
+
+ fgets(tmpline, 80, tmpfile);
+ fclose(tmpfile);
+ sgi_gamma = atof(tmpline);
+ if (sgi_gamma > 0.0)
+ LUT_exponent = 1.0 / sgi_gamma;
+ }
+#elif defined(Macintosh)
+ LUT_exponent = 1.8 / 2.61;
+ /*
+ if (some_mac_function_that_returns_gamma(&mac_gamma))
+ LUT_exponent = mac_gamma / 2.61;
+ */
+#else
+ LUT_exponent = 1.0; /* assume no LUT: most PCs */
+#endif
+
+ /* the defaults above give 1.0, 1.3, 1.5 and 2.2, respectively: */
+ default_display_exponent = LUT_exponent * CRT_exponent;
+
+
+ /* If the user has set the SCREEN_GAMMA environment variable as suggested
+ * (somewhat imprecisely) in the libpng documentation, use that; otherwise
+ * use the default value we just calculated. Either way, the user may
+ * override this via a command-line option. */
+
+ if ((p = getenv("SCREEN_GAMMA")) != NULL) {
+ double exponent = atof(p);
+
+ if (exponent > 0.0)
+ default_gamma = 1.0 / exponent;
+ }
+
+ if (default_gamma == 0.0)
+ default_gamma = 1.0 / default_display_exponent;
+
+
+ /* Now parse the command line for options and the PNM filename. */
+
+ while (*++argv && !error) {
+ if (!strncmp(*argv, "-i", 2)) {
+ wpng_info.interlaced = TRUE;
+ } else if (!strncmp(*argv, "-time", 3)) {
+ wpng_info.modtime = time(NULL);
+ wpng_info.have_time = TRUE;
+ } else if (!strncmp(*argv, "-text", 3)) {
+ text = TRUE;
+ } else if (!strncmp(*argv, "-gamma", 2)) {
+ if (!*++argv)
+ ++error;
+ else {
+ wpng_info.gamma = atof(*argv);
+ if (wpng_info.gamma <= 0.0)
+ ++error;
+ else if (wpng_info.gamma > 1.01)
+ fprintf(stderr, PROGNAME
+ " warning: file gammas are usually less than 1.0\n");
+ }
+ } else if (!strncmp(*argv, "-bgcolor", 4)) {
+ if (!*++argv)
+ ++error;
+ else {
+ bgstr = *argv;
+ if (strlen(bgstr) != 7 || bgstr[0] != '#')
+ ++error;
+ else {
+ unsigned r, g, b; /* this way quiets compiler warnings */
+
+ sscanf(bgstr+1, "%2x%2x%2x", &r, &g, &b);
+ wpng_info.bg_red = (uch)r;
+ wpng_info.bg_green = (uch)g;
+ wpng_info.bg_blue = (uch)b;
+ wpng_info.have_bg = TRUE;
+ }
+ }
+ } else {
+ if (**argv != '-') {
+ inname = *argv;
+ if (argv[1]) /* shouldn't be any more args after filename */
+ ++error;
+ } else
+ ++error; /* not expecting any other options */
+ }
+ }
+
+
+ /* open the input and output files, or register an error and abort */
+
+ if (!inname) {
+ if (isatty(0)) {
+ fprintf(stderr, PROGNAME
+ ": must give input filename or provide image data via stdin\n");
+ ++error;
+ } else {
+#ifdef DOS_OS2_W32
+ /* some buggy C libraries require BOTH setmode() and fdopen(bin) */
+ setmode(fileno(stdin), O_BINARY);
+ setmode(fileno(stdout), O_BINARY);
+#endif
+ if ((wpng_info.infile = fdopen(fileno(stdin), "rb")) == NULL) {
+ fprintf(stderr, PROGNAME
+ ": unable to reopen stdin in binary mode\n");
+ ++error;
+ } else
+ if ((wpng_info.outfile = fdopen(fileno(stdout), "wb")) == NULL) {
+ fprintf(stderr, PROGNAME
+ ": unable to reopen stdout in binary mode\n");
+ fclose(wpng_info.infile);
+ ++error;
+ } else
+ wpng_info.filter = TRUE;
+ }
+ } else if ((len = strlen(inname)) > 250) {
+ fprintf(stderr, PROGNAME ": input filename is too long [%d chars]\n",
+ len);
+ ++error;
+ } else if (!(wpng_info.infile = fopen(inname, "rb"))) {
+ fprintf(stderr, PROGNAME ": can't open input file [%s]\n", inname);
+ ++error;
+ }
+
+ if (!error) {
+ fgets(pnmline, 256, wpng_info.infile);
+ if (pnmline[0] != 'P' || ((pnmchar = pnmline[1]) != '5' &&
+ pnmchar != '6' && pnmchar != '8'))
+ {
+ fprintf(stderr, PROGNAME
+ ": input file [%s] is not a binary PGM, PPM or PAM file\n",
+ inname);
+ ++error;
+ } else {
+ wpng_info.pnmtype = (int)(pnmchar - '0');
+ if (wpng_info.pnmtype != 8)
+ wpng_info.have_bg = FALSE; /* no need for bg if opaque */
+ do {
+ fgets(pnmline, 256, wpng_info.infile); /* lose any comments */
+ } while (pnmline[0] == '#');
+ sscanf(pnmline, "%ld %ld", &wpng_info.width, &wpng_info.height);
+ do {
+ fgets(pnmline, 256, wpng_info.infile); /* more comment lines */
+ } while (pnmline[0] == '#');
+ sscanf(pnmline, "%d", &maxval);
+ if (wpng_info.width <= 0L || wpng_info.height <= 0L ||
+ maxval != 255)
+ {
+ fprintf(stderr, PROGNAME
+ ": only positive width/height, maxval == 255 allowed \n");
+ ++error;
+ }
+ wpng_info.sample_depth = 8; /* <==> maxval 255 */
+
+ if (!wpng_info.filter) {
+ /* make outname from inname */
+ if ((p = strrchr(inname, '.')) == NULL ||
+ (p - inname) != (len - 4))
+ {
+ strcpy(outname, inname);
+ strcpy(outname+len, ".png");
+ } else {
+ len -= 4;
+ strncpy(outname, inname, len);
+ strcpy(outname+len, ".png");
+ }
+ /* check if outname already exists; if not, open */
+ if ((wpng_info.outfile = fopen(outname, "rb")) != NULL) {
+ fprintf(stderr, PROGNAME ": output file exists [%s]\n",
+ outname);
+ fclose(wpng_info.outfile);
+ ++error;
+ } else if (!(wpng_info.outfile = fopen(outname, "wb"))) {
+ fprintf(stderr, PROGNAME ": can't open output file [%s]\n",
+ outname);
+ ++error;
+ }
+ }
+ }
+ if (error) {
+ fclose(wpng_info.infile);
+ wpng_info.infile = NULL;
+ if (wpng_info.filter) {
+ fclose(wpng_info.outfile);
+ wpng_info.outfile = NULL;
+ }
+ }
+ }
+
+
+ /* if we had any errors, print usage and die horrible death...arrr! */
+
+ if (error) {
+ fprintf(stderr, "\n%s %s: %s\n", PROGNAME, VERSION, APPNAME);
+ writepng_version_info();
+ fprintf(stderr, "\n"
+"Usage: %s [-gamma exp] [-bgcolor bg] [-text] [-time] [-interlace] pnmfile\n"
+"or: ... | %s [-gamma exp] [-bgcolor bg] [-text] [-time] [-interlace] | ...\n"
+ " exp \ttransfer-function exponent (``gamma'') of the image in\n"
+ "\t\t floating-point format (e.g., ``%.5f''); if image looks\n"
+ "\t\t correct on given display system, image gamma is equal to\n"
+ "\t\t inverse of display-system exponent, i.e., 1 / (LUT * CRT)\n"
+ "\t\t (where LUT = lookup-table exponent and CRT = CRT exponent;\n"
+ "\t\t first varies, second is usually 2.2, all are positive)\n"
+ " bg \tdesired background color for alpha-channel images, in\n"
+ "\t\t 7-character hex RGB format (e.g., ``#ff7700'' for orange:\n"
+ "\t\t same as HTML colors)\n"
+ " -text\tprompt interactively for text info (tEXt chunks)\n"
+ " -time\tinclude a tIME chunk (last modification time)\n"
+ " -interlace\twrite interlaced PNG image\n"
+ "\n"
+"pnmfile or stdin must be a binary PGM (`P5'), PPM (`P6') or (extremely\n"
+"unofficial and unsupported!) PAM (`P8') file. Currently it is required\n"
+"to have maxval == 255 (i.e., no scaling). If pnmfile is specified, it\n"
+"is converted to the corresponding PNG file with the same base name but a\n"
+"``.png'' extension; files read from stdin are converted and sent to stdout.\n"
+"The conversion is progressive (low memory usage) unless interlacing is\n"
+"requested; in that case the whole image will be buffered in memory and\n"
+"written in one call.\n"
+ "\n", PROGNAME, PROGNAME, default_gamma);
+ exit(1);
+ }
+
+
+ /* prepare the text buffers for libpng's use; note that even though
+ * PNG's png_text struct includes a length field, we don't have to fill
+ * it out */
+
+ if (text &&
+#ifndef DOS_OS2_W32
+ (keybd = fdopen(fileno(stderr), "r")) != NULL &&
+#endif
+ (textbuf = (char *)malloc((5 + 9)*75)) != NULL)
+ {
+ int i, valid, result;
+
+ fprintf(stderr,
+ "Enter text info (no more than 72 characters per line);\n");
+ fprintf(stderr, "to skip a field, hit the <Enter> key.\n");
+ /* note: just <Enter> leaves len == 1 */
+
+ do {
+ valid = TRUE;
+ p = textbuf + TEXT_TITLE_OFFSET;
+ fprintf(stderr, " Title: ");
+ fflush(stderr);
+ if (FGETS(p, 74, keybd) && (len = strlen(p)) > 1) {
+ if (p[len-1] == '\n')
+ p[--len] = '\0';
+ wpng_info.title = p;
+ wpng_info.have_text |= TEXT_TITLE;
+ if ((result = wpng_isvalid_latin1((uch *)p, len)) >= 0) {
+ fprintf(stderr, " " PROGNAME " warning: character code"
+ " %u is %sdiscouraged by the PNG\n specification "
+ "[first occurrence was at character position #%d]\n",
+ (unsigned)p[result], (p[result] == 27)? "strongly " : "",
+ result+1);
+ fflush(stderr);
+#ifdef FORBID_LATIN1_CTRL
+ wpng_info.have_text &= ~TEXT_TITLE;
+ valid = FALSE;
+#else
+ if (p[result] == 27) { /* escape character */
+ wpng_info.have_text &= ~TEXT_TITLE;
+ valid = FALSE;
+ }
+#endif
+ }
+ }
+ } while (!valid);
+
+ do {
+ valid = TRUE;
+ p = textbuf + TEXT_AUTHOR_OFFSET;
+ fprintf(stderr, " Author: ");
+ fflush(stderr);
+ if (FGETS(p, 74, keybd) && (len = strlen(p)) > 1) {
+ if (p[len-1] == '\n')
+ p[--len] = '\0';
+ wpng_info.author = p;
+ wpng_info.have_text |= TEXT_AUTHOR;
+ if ((result = wpng_isvalid_latin1((uch *)p, len)) >= 0) {
+ fprintf(stderr, " " PROGNAME " warning: character code"
+ " %u is %sdiscouraged by the PNG\n specification "
+ "[first occurrence was at character position #%d]\n",
+ (unsigned)p[result], (p[result] == 27)? "strongly " : "",
+ result+1);
+ fflush(stderr);
+#ifdef FORBID_LATIN1_CTRL
+ wpng_info.have_text &= ~TEXT_AUTHOR;
+ valid = FALSE;
+#else
+ if (p[result] == 27) { /* escape character */
+ wpng_info.have_text &= ~TEXT_AUTHOR;
+ valid = FALSE;
+ }
+#endif
+ }
+ }
+ } while (!valid);
+
+ do {
+ valid = TRUE;
+ p = textbuf + TEXT_DESC_OFFSET;
+ fprintf(stderr, " Description (up to 9 lines):\n");
+ for (i = 1; i < 10; ++i) {
+ fprintf(stderr, " [%d] ", i);
+ fflush(stderr);
+ if (FGETS(p, 74, keybd) && (len = strlen(p)) > 1)
+ p += len; /* now points at NULL; char before is newline */
+ else
+ break;
+ }
+ if ((len = p - (textbuf + TEXT_DESC_OFFSET)) > 1) {
+ if (p[-1] == '\n') {
+ p[-1] = '\0';
+ --len;
+ }
+ wpng_info.desc = textbuf + TEXT_DESC_OFFSET;
+ wpng_info.have_text |= TEXT_DESC;
+ p = textbuf + TEXT_DESC_OFFSET;
+ if ((result = wpng_isvalid_latin1((uch *)p, len)) >= 0) {
+ fprintf(stderr, " " PROGNAME " warning: character code"
+ " %u is %sdiscouraged by the PNG\n specification "
+ "[first occurrence was at character position #%d]\n",
+ (unsigned)p[result], (p[result] == 27)? "strongly " : "",
+ result+1);
+ fflush(stderr);
+#ifdef FORBID_LATIN1_CTRL
+ wpng_info.have_text &= ~TEXT_DESC;
+ valid = FALSE;
+#else
+ if (p[result] == 27) { /* escape character */
+ wpng_info.have_text &= ~TEXT_DESC;
+ valid = FALSE;
+ }
+#endif
+ }
+ }
+ } while (!valid);
+
+ do {
+ valid = TRUE;
+ p = textbuf + TEXT_COPY_OFFSET;
+ fprintf(stderr, " Copyright: ");
+ fflush(stderr);
+ if (FGETS(p, 74, keybd) && (len = strlen(p)) > 1) {
+ if (p[len-1] == '\n')
+ p[--len] = '\0';
+ wpng_info.copyright = p;
+ wpng_info.have_text |= TEXT_COPY;
+ if ((result = wpng_isvalid_latin1((uch *)p, len)) >= 0) {
+ fprintf(stderr, " " PROGNAME " warning: character code"
+ " %u is %sdiscouraged by the PNG\n specification "
+ "[first occurrence was at character position #%d]\n",
+ (unsigned)p[result], (p[result] == 27)? "strongly " : "",
+ result+1);
+ fflush(stderr);
+#ifdef FORBID_LATIN1_CTRL
+ wpng_info.have_text &= ~TEXT_COPY;
+ valid = FALSE;
+#else
+ if (p[result] == 27) { /* escape character */
+ wpng_info.have_text &= ~TEXT_COPY;
+ valid = FALSE;
+ }
+#endif
+ }
+ }
+ } while (!valid);
+
+ do {
+ valid = TRUE;
+ p = textbuf + TEXT_EMAIL_OFFSET;
+ fprintf(stderr, " E-mail: ");
+ fflush(stderr);
+ if (FGETS(p, 74, keybd) && (len = strlen(p)) > 1) {
+ if (p[len-1] == '\n')
+ p[--len] = '\0';
+ wpng_info.email = p;
+ wpng_info.have_text |= TEXT_EMAIL;
+ if ((result = wpng_isvalid_latin1((uch *)p, len)) >= 0) {
+ fprintf(stderr, " " PROGNAME " warning: character code"
+ " %u is %sdiscouraged by the PNG\n specification "
+ "[first occurrence was at character position #%d]\n",
+ (unsigned)p[result], (p[result] == 27)? "strongly " : "",
+ result+1);
+ fflush(stderr);
+#ifdef FORBID_LATIN1_CTRL
+ wpng_info.have_text &= ~TEXT_EMAIL;
+ valid = FALSE;
+#else
+ if (p[result] == 27) { /* escape character */
+ wpng_info.have_text &= ~TEXT_EMAIL;
+ valid = FALSE;
+ }
+#endif
+ }
+ }
+ } while (!valid);
+
+ do {
+ valid = TRUE;
+ p = textbuf + TEXT_URL_OFFSET;
+ fprintf(stderr, " URL: ");
+ fflush(stderr);
+ if (FGETS(p, 74, keybd) && (len = strlen(p)) > 1) {
+ if (p[len-1] == '\n')
+ p[--len] = '\0';
+ wpng_info.url = p;
+ wpng_info.have_text |= TEXT_URL;
+ if ((result = wpng_isvalid_latin1((uch *)p, len)) >= 0) {
+ fprintf(stderr, " " PROGNAME " warning: character code"
+ " %u is %sdiscouraged by the PNG\n specification "
+ "[first occurrence was at character position #%d]\n",
+ (unsigned)p[result], (p[result] == 27)? "strongly " : "",
+ result+1);
+ fflush(stderr);
+#ifdef FORBID_LATIN1_CTRL
+ wpng_info.have_text &= ~TEXT_URL;
+ valid = FALSE;
+#else
+ if (p[result] == 27) { /* escape character */
+ wpng_info.have_text &= ~TEXT_URL;
+ valid = FALSE;
+ }
+#endif
+ }
+ }
+ } while (!valid);
+
+#ifndef DOS_OS2_W32
+ fclose(keybd);
+#endif
+
+ } else if (text) {
+ fprintf(stderr, PROGNAME ": unable to allocate memory for text\n");
+ text = FALSE;
+ wpng_info.have_text = 0;
+ }
+
+
+ /* allocate libpng stuff, initialize transformations, write pre-IDAT data */
+
+ if ((rc = writepng_init(&wpng_info)) != 0) {
+ switch (rc) {
+ case 2:
+ fprintf(stderr, PROGNAME
+ ": libpng initialization problem (longjmp)\n");
+ break;
+ case 4:
+ fprintf(stderr, PROGNAME ": insufficient memory\n");
+ break;
+ case 11:
+ fprintf(stderr, PROGNAME
+ ": internal logic error (unexpected PNM type)\n");
+ break;
+ default:
+ fprintf(stderr, PROGNAME
+ ": unknown writepng_init() error\n");
+ break;
+ }
+ exit(rc);
+ }
+
+
+ /* free textbuf, since it's a completely local variable and all text info
+ * has just been written to the PNG file */
+
+ if (text && textbuf) {
+ free(textbuf);
+ textbuf = NULL;
+ }
+
+
+ /* calculate rowbytes on basis of image type; note that this becomes much
+ * more complicated if we choose to support PBM type, ASCII PNM types, or
+ * 16-bit-per-sample binary data [currently not an official NetPBM type] */
+
+ if (wpng_info.pnmtype == 5)
+ rowbytes = wpng_info.width;
+ else if (wpng_info.pnmtype == 6)
+ rowbytes = wpng_info.width * 3;
+ else /* if (wpng_info.pnmtype == 8) */
+ rowbytes = wpng_info.width * 4;
+
+
+ /* read and write the image, either in its entirety (if writing interlaced
+ * PNG) or row by row (if non-interlaced) */
+
+ fprintf(stderr, "Encoding image data...\n");
+ fflush(stderr);
+
+ if (wpng_info.interlaced) {
+ long i;
+ ulg bytes;
+ ulg image_bytes = rowbytes * wpng_info.height; /* overflow? */
+
+ wpng_info.image_data = (uch *)malloc(image_bytes);
+ wpng_info.row_pointers = (uch **)malloc(wpng_info.height*sizeof(uch *));
+ if (wpng_info.image_data == NULL || wpng_info.row_pointers == NULL) {
+ fprintf(stderr, PROGNAME ": insufficient memory for image data\n");
+ writepng_cleanup(&wpng_info);
+ wpng_cleanup();
+ exit(5);
+ }
+ for (i = 0; i < wpng_info.height; ++i)
+ wpng_info.row_pointers[i] = wpng_info.image_data + i*rowbytes;
+ bytes = fread(wpng_info.image_data, 1, image_bytes, wpng_info.infile);
+ if (bytes != image_bytes) {
+ fprintf(stderr, PROGNAME ": expected %lu bytes, got %lu bytes\n",
+ image_bytes, bytes);
+ fprintf(stderr, " (continuing anyway)\n");
+ }
+ if (writepng_encode_image(&wpng_info) != 0) {
+ fprintf(stderr, PROGNAME
+ ": libpng problem (longjmp) while writing image data\n");
+ writepng_cleanup(&wpng_info);
+ wpng_cleanup();
+ exit(2);
+ }
+
+ } else /* not interlaced: write progressively (row by row) */ {
+ long j;
+ ulg bytes;
+
+ wpng_info.image_data = (uch *)malloc(rowbytes);
+ if (wpng_info.image_data == NULL) {
+ fprintf(stderr, PROGNAME ": insufficient memory for row data\n");
+ writepng_cleanup(&wpng_info);
+ wpng_cleanup();
+ exit(5);
+ }
+ error = 0;
+ for (j = wpng_info.height; j > 0L; --j) {
+ bytes = fread(wpng_info.image_data, 1, rowbytes, wpng_info.infile);
+ if (bytes != rowbytes) {
+ fprintf(stderr, PROGNAME
+ ": expected %lu bytes, got %lu bytes (row %ld)\n", rowbytes,
+ bytes, wpng_info.height-j);
+ ++error;
+ break;
+ }
+ if (writepng_encode_row(&wpng_info) != 0) {
+ fprintf(stderr, PROGNAME
+ ": libpng problem (longjmp) while writing row %ld\n",
+ wpng_info.height-j);
+ ++error;
+ break;
+ }
+ }
+ if (error) {
+ writepng_cleanup(&wpng_info);
+ wpng_cleanup();
+ exit(2);
+ }
+ if (writepng_encode_finish(&wpng_info) != 0) {
+ fprintf(stderr, PROGNAME ": error on final libpng call\n");
+ writepng_cleanup(&wpng_info);
+ wpng_cleanup();
+ exit(2);
+ }
+ }
+
+
+ /* OK, we're done (successfully): clean up all resources and quit */
+
+ fprintf(stderr, "Done.\n");
+ fflush(stderr);
+
+ writepng_cleanup(&wpng_info);
+ wpng_cleanup();
+
+ return 0;
+}
+
+
+
+
+
+static int wpng_isvalid_latin1(uch *p, int len)
+{
+ int i, result = -1;
+
+ for (i = 0; i < len; ++i) {
+ if (p[i] == 10 || (p[i] > 31 && p[i] < 127) || p[i] > 160)
+ continue; /* character is completely OK */
+ if (result < 0 || (p[result] != 27 && p[i] == 27))
+ result = i; /* mark location of first questionable one */
+ } /* or of first escape character (bad) */
+
+ return result;
+}
+
+
+
+
+
+static void wpng_cleanup(void)
+{
+ if (wpng_info.outfile) {
+ fclose(wpng_info.outfile);
+ wpng_info.outfile = NULL;
+ }
+
+ if (wpng_info.infile) {
+ fclose(wpng_info.infile);
+ wpng_info.infile = NULL;
+ }
+
+ if (wpng_info.image_data) {
+ free(wpng_info.image_data);
+ wpng_info.image_data = NULL;
+ }
+
+ if (wpng_info.row_pointers) {
+ free(wpng_info.row_pointers);
+ wpng_info.row_pointers = NULL;
+ }
+}
+
+
+
+
+#ifdef DOS_OS2_W32
+
+static char *dos_kbd_gets(char *buf, int len)
+{
+ int ch, count=0;
+
+ do {
+ buf[count++] = ch = getche();
+ } while (ch != '\r' && count < len-1);
+
+ buf[count--] = '\0'; /* terminate string */
+ if (buf[count] == '\r') /* Enter key makes CR, so change to newline */
+ buf[count] = '\n';
+
+ fprintf(stderr, "\n"); /* Enter key does *not* cause a newline */
+ fflush(stderr);
+
+ return buf;
+}
+
+#endif /* DOS_OS2_W32 */
diff --git a/libpng/contrib/gregbook/writepng.c b/libpng/contrib/gregbook/writepng.c
new file mode 100644
index 0000000..c5c9534
--- /dev/null
+++ b/libpng/contrib/gregbook/writepng.c
@@ -0,0 +1,401 @@
+/*---------------------------------------------------------------------------
+
+ wpng - simple PNG-writing program writepng.c
+
+ ---------------------------------------------------------------------------
+
+ Copyright (c) 1998-2007 Greg Roelofs. All rights reserved.
+
+ This software is provided "as is," without warranty of any kind,
+ express or implied. In no event shall the author or contributors
+ be held liable for any damages arising in any way from the use of
+ this software.
+
+ The contents of this file are DUAL-LICENSED. You may modify and/or
+ redistribute this software according to the terms of one of the
+ following two licenses (at your option):
+
+
+ LICENSE 1 ("BSD-like with advertising clause"):
+
+ Permission is granted to anyone to use this software for any purpose,
+ including commercial applications, and to alter it and redistribute
+ it freely, subject to the following restrictions:
+
+ 1. Redistributions of source code must retain the above copyright
+ notice, disclaimer, and this list of conditions.
+ 2. Redistributions in binary form must reproduce the above copyright
+ notice, disclaimer, and this list of conditions in the documenta-
+ tion and/or other materials provided with the distribution.
+ 3. All advertising materials mentioning features or use of this
+ software must display the following acknowledgment:
+
+ This product includes software developed by Greg Roelofs
+ and contributors for the book, "PNG: The Definitive Guide,"
+ published by O'Reilly and Associates.
+
+
+ LICENSE 2 (GNU GPL v2 or later):
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ ---------------------------------------------------------------------------*/
+
+
+#include <stdlib.h> /* for exit() prototype */
+#include <zlib.h>
+
+#include "png.h" /* libpng header, includes setjmp.h */
+#include "writepng.h" /* typedefs, common macros, public prototypes */
+
+
+/* local prototype */
+
+static void writepng_error_handler(png_structp png_ptr, png_const_charp msg);
+
+
+
+void writepng_version_info(void)
+{
+ fprintf(stderr, " Compiled with libpng %s; using libpng %s.\n",
+ PNG_LIBPNG_VER_STRING, png_libpng_ver);
+ fprintf(stderr, " Compiled with zlib %s; using zlib %s.\n",
+ ZLIB_VERSION, zlib_version);
+}
+
+
+
+
+/* returns 0 for success, 2 for libpng problem, 4 for out of memory, 11 for
+ * unexpected pnmtype; note that outfile might be stdout */
+
+int writepng_init(mainprog_info *mainprog_ptr)
+{
+ png_structp png_ptr; /* note: temporary variables! */
+ png_infop info_ptr;
+ int color_type, interlace_type;
+
+
+ /* could also replace libpng warning-handler (final NULL), but no need: */
+
+ png_ptr = png_create_write_struct(png_get_libpng_ver(NULL), mainprog_ptr,
+ writepng_error_handler, NULL);
+ if (!png_ptr)
+ return 4; /* out of memory */
+
+ info_ptr = png_create_info_struct(png_ptr);
+ if (!info_ptr) {
+ png_destroy_write_struct(&png_ptr, NULL);
+ return 4; /* out of memory */
+ }
+
+
+ /* setjmp() must be called in every function that calls a PNG-writing
+ * libpng function, unless an alternate error handler was installed--
+ * but compatible error handlers must either use longjmp() themselves
+ * (as in this program) or some other method to return control to
+ * application code, so here we go: */
+
+ if (setjmp(mainprog_ptr->jmpbuf)) {
+ png_destroy_write_struct(&png_ptr, &info_ptr);
+ return 2;
+ }
+
+
+ /* make sure outfile is (re)opened in BINARY mode */
+
+ png_init_io(png_ptr, mainprog_ptr->outfile);
+
+
+ /* set the compression levels--in general, always want to leave filtering
+ * turned on (except for palette images) and allow all of the filters,
+ * which is the default; want 32K zlib window, unless entire image buffer
+ * is 16K or smaller (unknown here)--also the default; usually want max
+ * compression (NOT the default); and remaining compression flags should
+ * be left alone */
+
+ png_set_compression_level(png_ptr, Z_BEST_COMPRESSION);
+/*
+ >> this is default for no filtering; Z_FILTERED is default otherwise:
+ png_set_compression_strategy(png_ptr, Z_DEFAULT_STRATEGY);
+ >> these are all defaults:
+ png_set_compression_mem_level(png_ptr, 8);
+ png_set_compression_window_bits(png_ptr, 15);
+ png_set_compression_method(png_ptr, 8);
+ */
+
+
+ /* set the image parameters appropriately */
+
+ if (mainprog_ptr->pnmtype == 5)
+ color_type = PNG_COLOR_TYPE_GRAY;
+ else if (mainprog_ptr->pnmtype == 6)
+ color_type = PNG_COLOR_TYPE_RGB;
+ else if (mainprog_ptr->pnmtype == 8)
+ color_type = PNG_COLOR_TYPE_RGB_ALPHA;
+ else {
+ png_destroy_write_struct(&png_ptr, &info_ptr);
+ return 11;
+ }
+
+ interlace_type = mainprog_ptr->interlaced? PNG_INTERLACE_ADAM7 :
+ PNG_INTERLACE_NONE;
+
+ png_set_IHDR(png_ptr, info_ptr, mainprog_ptr->width, mainprog_ptr->height,
+ mainprog_ptr->sample_depth, color_type, interlace_type,
+ PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
+
+ if (mainprog_ptr->gamma > 0.0)
+ png_set_gAMA(png_ptr, info_ptr, mainprog_ptr->gamma);
+
+ if (mainprog_ptr->have_bg) { /* we know it's RGBA, not gray+alpha */
+ png_color_16 background;
+
+ background.red = mainprog_ptr->bg_red;
+ background.green = mainprog_ptr->bg_green;
+ background.blue = mainprog_ptr->bg_blue;
+ png_set_bKGD(png_ptr, info_ptr, &background);
+ }
+
+ if (mainprog_ptr->have_time) {
+ png_time modtime;
+
+ png_convert_from_time_t(&modtime, mainprog_ptr->modtime);
+ png_set_tIME(png_ptr, info_ptr, &modtime);
+ }
+
+ if (mainprog_ptr->have_text) {
+ png_text text[6];
+ int num_text = 0;
+
+ if (mainprog_ptr->have_text & TEXT_TITLE) {
+ text[num_text].compression = PNG_TEXT_COMPRESSION_NONE;
+ text[num_text].key = "Title";
+ text[num_text].text = mainprog_ptr->title;
+ ++num_text;
+ }
+ if (mainprog_ptr->have_text & TEXT_AUTHOR) {
+ text[num_text].compression = PNG_TEXT_COMPRESSION_NONE;
+ text[num_text].key = "Author";
+ text[num_text].text = mainprog_ptr->author;
+ ++num_text;
+ }
+ if (mainprog_ptr->have_text & TEXT_DESC) {
+ text[num_text].compression = PNG_TEXT_COMPRESSION_NONE;
+ text[num_text].key = "Description";
+ text[num_text].text = mainprog_ptr->desc;
+ ++num_text;
+ }
+ if (mainprog_ptr->have_text & TEXT_COPY) {
+ text[num_text].compression = PNG_TEXT_COMPRESSION_NONE;
+ text[num_text].key = "Copyright";
+ text[num_text].text = mainprog_ptr->copyright;
+ ++num_text;
+ }
+ if (mainprog_ptr->have_text & TEXT_EMAIL) {
+ text[num_text].compression = PNG_TEXT_COMPRESSION_NONE;
+ text[num_text].key = "E-mail";
+ text[num_text].text = mainprog_ptr->email;
+ ++num_text;
+ }
+ if (mainprog_ptr->have_text & TEXT_URL) {
+ text[num_text].compression = PNG_TEXT_COMPRESSION_NONE;
+ text[num_text].key = "URL";
+ text[num_text].text = mainprog_ptr->url;
+ ++num_text;
+ }
+ png_set_text(png_ptr, info_ptr, text, num_text);
+ }
+
+
+ /* write all chunks up to (but not including) first IDAT */
+
+ png_write_info(png_ptr, info_ptr);
+
+
+ /* if we wanted to write any more text info *after* the image data, we
+ * would set up text struct(s) here and call png_set_text() again, with
+ * just the new data; png_set_tIME() could also go here, but it would
+ * have no effect since we already called it above (only one tIME chunk
+ * allowed) */
+
+
+ /* set up the transformations: for now, just pack low-bit-depth pixels
+ * into bytes (one, two or four pixels per byte) */
+
+ png_set_packing(png_ptr);
+/* png_set_shift(png_ptr, &sig_bit); to scale low-bit-depth values */
+
+
+ /* make sure we save our pointers for use in writepng_encode_image() */
+
+ mainprog_ptr->png_ptr = png_ptr;
+ mainprog_ptr->info_ptr = info_ptr;
+
+
+ /* OK, that's all we need to do for now; return happy */
+
+ return 0;
+}
+
+
+
+
+
+/* returns 0 for success, 2 for libpng (longjmp) problem */
+
+int writepng_encode_image(mainprog_info *mainprog_ptr)
+{
+ png_structp png_ptr = (png_structp)mainprog_ptr->png_ptr;
+ png_infop info_ptr = (png_infop)mainprog_ptr->info_ptr;
+
+
+ /* as always, setjmp() must be called in every function that calls a
+ * PNG-writing libpng function */
+
+ if (setjmp(mainprog_ptr->jmpbuf)) {
+ png_destroy_write_struct(&png_ptr, &info_ptr);
+ mainprog_ptr->png_ptr = NULL;
+ mainprog_ptr->info_ptr = NULL;
+ return 2;
+ }
+
+
+ /* and now we just write the whole image; libpng takes care of interlacing
+ * for us */
+
+ png_write_image(png_ptr, mainprog_ptr->row_pointers);
+
+
+ /* since that's it, we also close out the end of the PNG file now--if we
+ * had any text or time info to write after the IDATs, second argument
+ * would be info_ptr, but we optimize slightly by sending NULL pointer: */
+
+ png_write_end(png_ptr, NULL);
+
+ return 0;
+}
+
+
+
+
+
+/* returns 0 if succeeds, 2 if libpng problem */
+
+int writepng_encode_row(mainprog_info *mainprog_ptr) /* NON-interlaced only! */
+{
+ png_structp png_ptr = (png_structp)mainprog_ptr->png_ptr;
+ png_infop info_ptr = (png_infop)mainprog_ptr->info_ptr;
+
+
+ /* as always, setjmp() must be called in every function that calls a
+ * PNG-writing libpng function */
+
+ if (setjmp(mainprog_ptr->jmpbuf)) {
+ png_destroy_write_struct(&png_ptr, &info_ptr);
+ mainprog_ptr->png_ptr = NULL;
+ mainprog_ptr->info_ptr = NULL;
+ return 2;
+ }
+
+
+ /* image_data points at our one row of image data */
+
+ png_write_row(png_ptr, mainprog_ptr->image_data);
+
+ return 0;
+}
+
+
+
+
+
+/* returns 0 if succeeds, 2 if libpng problem */
+
+int writepng_encode_finish(mainprog_info *mainprog_ptr) /* NON-interlaced! */
+{
+ png_structp png_ptr = (png_structp)mainprog_ptr->png_ptr;
+ png_infop info_ptr = (png_infop)mainprog_ptr->info_ptr;
+
+
+ /* as always, setjmp() must be called in every function that calls a
+ * PNG-writing libpng function */
+
+ if (setjmp(mainprog_ptr->jmpbuf)) {
+ png_destroy_write_struct(&png_ptr, &info_ptr);
+ mainprog_ptr->png_ptr = NULL;
+ mainprog_ptr->info_ptr = NULL;
+ return 2;
+ }
+
+
+ /* close out PNG file; if we had any text or time info to write after
+ * the IDATs, second argument would be info_ptr: */
+
+ png_write_end(png_ptr, NULL);
+
+ return 0;
+}
+
+
+
+
+
+void writepng_cleanup(mainprog_info *mainprog_ptr)
+{
+ png_structp png_ptr = (png_structp)mainprog_ptr->png_ptr;
+ png_infop info_ptr = (png_infop)mainprog_ptr->info_ptr;
+
+ if (png_ptr && info_ptr)
+ png_destroy_write_struct(&png_ptr, &info_ptr);
+}
+
+
+
+
+
+static void writepng_error_handler(png_structp png_ptr, png_const_charp msg)
+{
+ mainprog_info *mainprog_ptr;
+
+ /* This function, aside from the extra step of retrieving the "error
+ * pointer" (below) and the fact that it exists within the application
+ * rather than within libpng, is essentially identical to libpng's
+ * default error handler. The second point is critical: since both
+ * setjmp() and longjmp() are called from the same code, they are
+ * guaranteed to have compatible notions of how big a jmp_buf is,
+ * regardless of whether _BSD_SOURCE or anything else has (or has not)
+ * been defined. */
+
+ fprintf(stderr, "writepng libpng error: %s\n", msg);
+ fflush(stderr);
+
+ mainprog_ptr = png_get_error_ptr(png_ptr);
+ if (mainprog_ptr == NULL) { /* we are completely hosed now */
+ fprintf(stderr,
+ "writepng severe error: jmpbuf not recoverable; terminating.\n");
+ fflush(stderr);
+ exit(99);
+ }
+
+ /* Now we have our data structure we can use the information in it
+ * to return control to our own higher level code (all the points
+ * where 'setjmp' is called in this file.) This will work with other
+ * error handling mechanisms as well - libpng always calls png_error
+ * when it can proceed no further, thus, so long as the error handler
+ * is intercepted, application code can do its own error recovery.
+ */
+ longjmp(mainprog_ptr->jmpbuf, 1);
+}
diff --git a/libpng/contrib/gregbook/writepng.h b/libpng/contrib/gregbook/writepng.h
new file mode 100644
index 0000000..78b966b
--- /dev/null
+++ b/libpng/contrib/gregbook/writepng.h
@@ -0,0 +1,133 @@
+/*---------------------------------------------------------------------------
+
+ wpng - simple PNG-writing program writepng.h
+
+ ---------------------------------------------------------------------------
+
+ Copyright (c) 1998-2007 Greg Roelofs. All rights reserved.
+
+ This software is provided "as is," without warranty of any kind,
+ express or implied. In no event shall the author or contributors
+ be held liable for any damages arising in any way from the use of
+ this software.
+
+ The contents of this file are DUAL-LICENSED. You may modify and/or
+ redistribute this software according to the terms of one of the
+ following two licenses (at your option):
+
+
+ LICENSE 1 ("BSD-like with advertising clause"):
+
+ Permission is granted to anyone to use this software for any purpose,
+ including commercial applications, and to alter it and redistribute
+ it freely, subject to the following restrictions:
+
+ 1. Redistributions of source code must retain the above copyright
+ notice, disclaimer, and this list of conditions.
+ 2. Redistributions in binary form must reproduce the above copyright
+ notice, disclaimer, and this list of conditions in the documenta-
+ tion and/or other materials provided with the distribution.
+ 3. All advertising materials mentioning features or use of this
+ software must display the following acknowledgment:
+
+ This product includes software developed by Greg Roelofs
+ and contributors for the book, "PNG: The Definitive Guide,"
+ published by O'Reilly and Associates.
+
+
+ LICENSE 2 (GNU GPL v2 or later):
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ ---------------------------------------------------------------------------*/
+
+#ifndef TRUE
+# define TRUE 1
+# define FALSE 0
+#endif
+
+#ifndef MAX
+# define MAX(a,b) ((a) > (b)? (a) : (b))
+# define MIN(a,b) ((a) < (b)? (a) : (b))
+#endif
+
+#ifdef DEBUG
+# define Trace(x) {fprintf x ; fflush(stderr); fflush(stdout);}
+#else
+# define Trace(x) ;
+#endif
+
+#define TEXT_TITLE 0x01
+#define TEXT_AUTHOR 0x02
+#define TEXT_DESC 0x04
+#define TEXT_COPY 0x08
+#define TEXT_EMAIL 0x10
+#define TEXT_URL 0x20
+
+#define TEXT_TITLE_OFFSET 0
+#define TEXT_AUTHOR_OFFSET 72
+#define TEXT_COPY_OFFSET (2*72)
+#define TEXT_EMAIL_OFFSET (3*72)
+#define TEXT_URL_OFFSET (4*72)
+#define TEXT_DESC_OFFSET (5*72)
+
+typedef unsigned char uch;
+typedef unsigned short ush;
+typedef unsigned long ulg;
+
+typedef struct _mainprog_info {
+ double gamma;
+ long width;
+ long height;
+ time_t modtime;
+ FILE *infile;
+ FILE *outfile;
+ void *png_ptr;
+ void *info_ptr;
+ uch *image_data;
+ uch **row_pointers;
+ char *title;
+ char *author;
+ char *desc;
+ char *copyright;
+ char *email;
+ char *url;
+ int filter; /* command-line-filter flag, not PNG row filter! */
+ int pnmtype;
+ int sample_depth;
+ int interlaced;
+ int have_bg;
+ int have_time;
+ int have_text;
+ jmp_buf jmpbuf;
+ uch bg_red;
+ uch bg_green;
+ uch bg_blue;
+} mainprog_info;
+
+
+/* prototypes for public functions in writepng.c */
+
+void writepng_version_info(void);
+
+int writepng_init(mainprog_info *mainprog_ptr);
+
+int writepng_encode_image(mainprog_info *mainprog_ptr);
+
+int writepng_encode_row(mainprog_info *mainprog_ptr);
+
+int writepng_encode_finish(mainprog_info *mainprog_ptr);
+
+void writepng_cleanup(mainprog_info *mainprog_ptr);
diff --git a/libpng/contrib/libtests/fakepng.c b/libpng/contrib/libtests/fakepng.c
new file mode 100644
index 0000000..6512c14
--- /dev/null
+++ b/libpng/contrib/libtests/fakepng.c
@@ -0,0 +1,65 @@
+/* Fake a PNG - just write it out directly.
+ *
+ * COPYRIGHT: Written by John Cunningham Bowler, 2014.
+ * To the extent possible under law, the author has waived all copyright and
+ * related or neighboring rights to this work. This work is published from:
+ * United States.
+ *
+ */
+
+#include <stdio.h>
+#include <zlib.h> /* for crc32 */
+
+void
+put_uLong(uLong val)
+{
+ putchar(val >> 24);
+ putchar(val >> 16);
+ putchar(val >> 8);
+ putchar(val >> 0);
+}
+
+void
+put_chunk(const unsigned char *chunk, uInt length)
+{
+ uLong crc;
+
+ put_uLong(length-4); /* Exclude the tag */
+
+ fwrite(chunk, length, 1, stdout);
+
+ crc = crc32(0, Z_NULL, 0);
+ put_uLong(crc32(crc, chunk, length));
+}
+
+const unsigned char signature[] =
+{
+ 137, 80, 78, 71, 13, 10, 26, 10
+};
+
+const unsigned char IHDR[] =
+{
+ 73, 72, 68, 82, /* IHDR */
+ 0, 0, 0, 1, /* width */
+ 0, 0, 0, 1, /* height */
+ 1, /* bit depth */
+ 0, /* color type: greyscale */
+ 0, /* compression method */
+ 0, /* filter method */
+ 0 /* interlace method: none */
+};
+
+const unsigned char unknown[] =
+{
+ 'u', 'n', 'K', 'n' /* "unKn" - private safe to copy */
+};
+
+int
+main(void)
+{
+ fwrite(signature, sizeof signature, 1, stdout);
+ put_chunk(IHDR, sizeof IHDR);
+
+ for (;;)
+ put_chunk(unknown, sizeof unknown);
+}
diff --git a/libpng/contrib/libtests/gentests.sh b/libpng/contrib/libtests/gentests.sh
new file mode 100755
index 0000000..f0f8d23
--- /dev/null
+++ b/libpng/contrib/libtests/gentests.sh
@@ -0,0 +1,102 @@
+#!/bin/sh
+#
+# Copyright (c) 2013 John Cunningham Bowler
+#
+# Last changed in libpng 1.6.0 [February 14, 2013]
+#
+# This code is released under the libpng license.
+# For conditions of distribution and use, see the disclaimer
+# and license in png.h
+#
+# Generate a set of PNG test images. The images are generated in a
+# sub-directory called 'tests' by default, however a command line argument will
+# change that name. The generation requires a built version of makepng in the
+# current directory.
+#
+usage(){
+ exec >&2
+ echo "$0 [<directory>]"
+ echo ' Generate a set of PNG test files in "directory" ("tests" by default)'
+ exit 1
+}
+
+mp="$PWD/makepng"
+test -x "$mp" || {
+ exec >&2
+ echo "$0: the 'makepng' program must exist"
+ echo " in the directory within which this program:"
+ echo " $mp"
+ echo " is executed"
+ usage
+}
+
+# Just one argument: the directory
+testdir="tests"
+test $# -gt 1 && {
+ testdir="$1"
+ shift
+}
+test $# -eq 0 || usage
+
+# Take care not to clobber something
+if test -e "$testdir"
+then
+ test -d "$testdir" || usage
+else
+ # mkdir -p isn't portable, so do the following
+ mkdir "$testdir" 2>/dev/null || mkdir -p "$testdir" || usage
+fi
+
+# This fails in a very satisfactory way if it's not accessible
+cd "$testdir"
+:>"test$$.png" || {
+ exec >&2
+ echo "$testdir: directory not writable"
+ usage
+}
+rm "test$$.png" || {
+ exec >&2
+ echo "$testdir: you have create but not write privileges here."
+ echo " This is unexpected. You have a spurion; "'"'"test$$.png"'"'"."
+ echo " You need to remove this yourself. Try a different directory."
+ exit 1
+}
+
+# Now call makepng ($mp) to create every file we can think of with a
+# reasonable name
+doit(){
+ for gamma in "" --sRGB --linear --1.8
+ do
+ case "$gamma" in
+ "")
+ gname=;;
+ --sRGB)
+ gname="-srgb";;
+ --linear)
+ gname="-lin";;
+ --1.8)
+ gname="-18";;
+ *)
+ gname="-$gamma";;
+ esac
+ "$mp" $gamma "$1" "$2" "test-$1-$2$gname.png"
+ done
+}
+#
+for ct in gray palette
+do
+ for bd in 1 2 4 8
+ do
+ doit "$ct" "$bd"
+ done
+done
+#
+doit "gray" "16"
+#
+for ct in gray-alpha rgb rgb-alpha
+do
+ for bd in 8 16
+ do
+ doit "$ct" "$bd"
+ done
+done
diff --git a/libpng/contrib/libtests/makepng.c b/libpng/contrib/libtests/makepng.c
new file mode 100644
index 0000000..60d96d1
--- /dev/null
+++ b/libpng/contrib/libtests/makepng.c
@@ -0,0 +1,1941 @@
+/* makepng.c */
+#define _ISOC99_SOURCE
+/* Copyright: */
+#define COPYRIGHT "\251 2013,2015 John Cunningham Bowler"
+/*
+ * Last changed in libpng 1.7.0 [(PENDING RELEASE)]
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * Make a test PNG image. The arguments are as follows:
+ *
+ * makepng [--sRGB|--linear|--1.8] [--tRNS] [--nofilters] \
+ * color-type bit-depth [file-name]
+ *
+ * The color-type may be numeric (and must match the numbers used by the PNG
+ * specification) or one of the format names listed below. The bit-depth is the
+ * component bit depth, or the pixel bit-depth for a color-mapped image.
+ *
+ * Without any options no color-space information is written, with the options
+ * an sRGB or the appropriate gAMA chunk is written. "1.8" refers to the
+ * display system used on older Apple computers to correct for high ambient
+ * light levels in the viewing environment; it applies a transform of
+ * approximately value^(1/1.45) to the color values and so a gAMA chunk of 65909
+ * is written (1.45/2.2).
+ *
+ * The image data is generated internally. Unless --color is given the images
+ * used are as follows:
+ *
+ * 1 channel: a square image with a diamond, the least luminous colors are on
+ * the edge of the image, the most luminous in the center.
+ *
+ * 2 channels: the color channel increases in luminosity from top to bottom, the
+ * alpha channel increases in opacity from left to right.
+ *
+ * 3 channels: linear combinations of, from the top-left corner clockwise,
+ * black, green, white, red.
+ *
+ * 4 channels: linear combinations of, from the top-left corner clockwise,
+ * transparent, red, green, blue.
+ *
+ * For color-mapped images a four channel color-map is used and if --tRNS is
+ * given the PNG file has a tRNS chunk, as follows:
+ *
+ * 1-bit: entry 0 is transparent-red, entry 1 is opaque-white
+ * 2-bit: entry 0: transparent-green
+ * entry 1: 40%-red
+ * entry 2: 80%-blue
+ * entry 3: opaque-white
+ * 4-bit: the 16 combinations of the 2-bit case
+ * 8-bit: the 256 combinations of the 4-bit case
+ *
+ * The palette always has 2^bit-depth entries and the tRNS chunk one fewer. The
+ * image is the 1-channel diamond, but using palette index, not luminosity.
+ *
+ * For formats other than color-mapped ones if --tRNS is specified a tRNS chunk
+ * is generated with all channels equal to the low bits of 0x0101.
+ *
+ * Image size is determined by the final pixel depth in bits, i.e. channels x
+ * bit-depth, as follows:
+ *
+ * 8 bits or less: 64x64
+ * 16 bits: 256x256
+ * More than 16 bits: 1024x1024
+ *
+ * Row filtering is the libpng default but may be turned off (the 'none' filter
+ * is used on every row) with the --nofilters option.
+ *
+ * The images are not interlaced.
+ *
+ * If file-name is given then the PNG is written to that file, else it is
+ * written to stdout. Notice that stdout is not supported on systems where, by
+ * default, it assumes text output; this program makes no attempt to change the
+ * text mode of stdout!
+ *
+ * makepng --color=<color> ...
+ *
+ * If --color is given then the whole image has that color, color-mapped images
+ * will have exactly one palette entry and all image files with be 16x16 in
+ * size. The color value is 1 to 4 decimal numbers as appropriate for the color
+ * type.
+ *
+ * makepng --small ...
+ *
+ * If --small is given the images are no larger than required to include every
+ * possible pixel value for the format.
+ *
+ * For formats with pixels 8 bits or fewer in size the images consist of a
+ * single row with 2^pixel-depth pixels, one of every possible value.
+ *
+ * For formats with 16-bit pixels a 256x256 image is generated containing every
+ * possible pixel value.
+ *
+ * For larger pixel sizes a 256x256 image is generated where the first row
+ * consists of each pixel that has identical byte values throughout the pixel
+ * followed by rows where the byte values differ within the pixel.
+ *
+ * In all cases the pixel values are arranged in such a way that the SUB and UP
+ * filters give byte sequences for maximal zlib compression. By default (if
+ * --nofilters is not given) the SUB filter is used on the first row and the UP
+ * filter on all following rows.
+ *
+ * The --small option is meant to provide good test-case coverage, however the
+ * images are not easy to examine visually. Without the --small option the
+ * images contain identical color values; the pixel values are adjusted
+ * according to the gamma encoding with no gamma encoding being interpreted as
+ * sRGB.
+ *
+ * LICENSING
+ * =========
+ *
+ * This code is copyright of the authors, see the COPYRIGHT define above. The
+ * code is licensed as above, using the libpng license. The code generates
+ * images which are solely the product of the code; the options choose which of
+ * the many possibilities to generate. The images that result (but not the code
+ * which generates them) are licensed as defined here:
+ *
+ * IMPORTANT: the COPYRIGHT #define must contain ISO-Latin-1 characters, the
+ * IMAGE_LICENSING #define must contain UTF-8 characters. The 'copyright'
+ * symbol 0xA9U (\251) in ISO-Latin-1 encoding and 0xC20xA9 (\302\251) in UTF-8.
+ */
+#define IMAGE_LICENSING "Dedicated to the public domain per Creative Commons "\
+ "license \"CC0 1.0\"; https://creativecommons.org/publicdomain/zero/1.0/"
+
+#include <stddef.h> /* for offsetof */
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+#include <math.h>
+#include <errno.h>
+#include <assert.h>
+#include <stdint.h>
+
+#if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H)
+# include <config.h>
+#endif
+
+/* Define the following to use this test against your installed libpng, rather
+ * than the one being built here:
+ */
+#ifdef PNG_FREESTANDING_TESTS
+# include <png.h>
+#else
+# include "../../png.h"
+#endif
+
+#include <zlib.h>
+
+/* Work round for GCC complaints about casting a (double) function result to
+ * an unsigned:
+ */
+static unsigned int
+flooru(double d)
+{
+ d = floor(d);
+ return (unsigned int)d;
+}
+
+static png_byte
+floorb(double d)
+{
+ d = floor(d);
+ return (png_byte)d;
+}
+
+/* This structure is used for inserting extra chunks (the --insert argument, not
+ * documented above.)
+ */
+typedef struct chunk_insert
+{
+ struct chunk_insert *next;
+ void (*insert)(png_structp, png_infop, int, png_charpp);
+ int nparams;
+ png_charp parameters[1];
+} chunk_insert;
+
+static unsigned int
+channels_of_type(int color_type)
+{
+ if (color_type & PNG_COLOR_MASK_PALETTE)
+ return 1;
+
+ else
+ {
+ int channels = 1;
+
+ if (color_type & PNG_COLOR_MASK_COLOR)
+ channels = 3;
+
+ if (color_type & PNG_COLOR_MASK_ALPHA)
+ return channels + 1;
+
+ else
+ return channels;
+ }
+}
+
+static unsigned int
+pixel_depth_of_type(int color_type, int bit_depth)
+{
+ return channels_of_type(color_type) * bit_depth;
+}
+
+static unsigned int
+image_size_of_type(int color_type, int bit_depth, unsigned int *colors,
+ int small)
+{
+ if (*colors)
+ return 16;
+
+ else
+ {
+ int pixel_depth = pixel_depth_of_type(color_type, bit_depth);
+
+ if (small)
+ {
+ if (pixel_depth <= 8) /* there will be one row */
+ return 1 << pixel_depth;
+
+ else
+ return 256;
+ }
+
+ else if (pixel_depth < 8)
+ return 64;
+
+ else if (pixel_depth > 16)
+ return 1024;
+
+ else
+ return 256;
+ }
+}
+
+static void
+set_color(png_colorp color, png_bytep trans, unsigned int red,
+ unsigned int green, unsigned int blue, unsigned int alpha,
+ png_const_bytep gamma_table)
+{
+ color->red = gamma_table[red];
+ color->green = gamma_table[green];
+ color->blue = gamma_table[blue];
+ *trans = (png_byte)alpha;
+}
+
+static int
+generate_palette(png_colorp palette, png_bytep trans, int bit_depth,
+ png_const_bytep gamma_table, unsigned int *colors)
+{
+ /*
+ * 1-bit: entry 0 is transparent-red, entry 1 is opaque-white
+ * 2-bit: entry 0: transparent-green
+ * entry 1: 40%-red
+ * entry 2: 80%-blue
+ * entry 3: opaque-white
+ * 4-bit: the 16 combinations of the 2-bit case
+ * 8-bit: the 256 combinations of the 4-bit case
+ */
+ switch (colors[0])
+ {
+ default:
+ fprintf(stderr, "makepng: --colors=...: invalid count %u\n",
+ colors[0]);
+ exit(1);
+
+ case 1:
+ set_color(palette+0, trans+0, colors[1], colors[1], colors[1], 255,
+ gamma_table);
+ return 1;
+
+ case 2:
+ set_color(palette+0, trans+0, colors[1], colors[1], colors[1],
+ colors[2], gamma_table);
+ return 1;
+
+ case 3:
+ set_color(palette+0, trans+0, colors[1], colors[2], colors[3], 255,
+ gamma_table);
+ return 1;
+
+ case 4:
+ set_color(palette+0, trans+0, colors[1], colors[2], colors[3],
+ colors[4], gamma_table);
+ return 1;
+
+ case 0:
+ if (bit_depth == 1)
+ {
+ set_color(palette+0, trans+0, 255, 0, 0, 0, gamma_table);
+ set_color(palette+1, trans+1, 255, 255, 255, 255, gamma_table);
+ return 2;
+ }
+
+ else
+ {
+ unsigned int size = 1U << (bit_depth/2); /* 2, 4 or 16 */
+ unsigned int x, y;
+ volatile unsigned int ip = 0;
+
+ for (x=0; x<size; ++x) for (y=0; y<size; ++y)
+ {
+ ip = x + (size * y);
+
+ /* size is at most 16, so the scaled value below fits in 16 bits
+ */
+# define interp(pos, c1, c2) ((pos * c1) + ((size-pos) * c2))
+# define xyinterp(x, y, c1, c2, c3, c4) (((size * size / 2) +\
+ (interp(x, c1, c2) * y + (size-y) * interp(x, c3, c4))) /\
+ (size*size))
+
+ set_color(palette+ip, trans+ip,
+ /* color: green, red,blue,white */
+ xyinterp(x, y, 0, 255, 0, 255),
+ xyinterp(x, y, 255, 0, 0, 255),
+ xyinterp(x, y, 0, 0, 255, 255),
+ /* alpha: 0, 102, 204, 255) */
+ xyinterp(x, y, 0, 102, 204, 255),
+ gamma_table);
+ }
+
+ return ip+1;
+ }
+ }
+}
+
+static void
+set_value(png_bytep row, size_t rowbytes, png_uint_32 x, unsigned int bit_depth,
+ png_uint_32 value, png_const_bytep gamma_table, double conv)
+{
+ unsigned int mask = (1U << bit_depth)-1;
+
+ x *= bit_depth; /* Maximum x is 4*1024, maximum bit_depth is 16 */
+
+ if (value <= mask)
+ {
+ png_uint_32 offset = x >> 3;
+
+ if (offset < rowbytes && (bit_depth < 16 || offset+1 < rowbytes))
+ {
+ row += offset;
+
+ switch (bit_depth)
+ {
+ case 1:
+ case 2:
+ case 4:
+ /* Don't gamma correct - values get smashed */
+ {
+ unsigned int shift = (8 - bit_depth) - (x & 0x7U);
+
+ mask <<= shift;
+ value = (value << shift) & mask;
+ *row = (png_byte)((*row & ~mask) | value);
+ }
+ return;
+
+ default:
+ fprintf(stderr, "makepng: bad bit depth (internal error)\n");
+ exit(1);
+
+ case 16:
+ value = flooru(65535*pow(value/65535.,conv)+.5);
+ *row++ = (png_byte)(value >> 8);
+ *row = (png_byte)value;
+ return;
+
+ case 8:
+ *row = gamma_table[value];
+ return;
+ }
+ }
+
+ else
+ {
+ fprintf(stderr, "makepng: row buffer overflow (internal error)\n");
+ exit(1);
+ }
+ }
+
+ else
+ {
+ fprintf(stderr, "makepng: component overflow (internal error)\n");
+ exit(1);
+ }
+}
+
+static int /* filter mask for row */
+generate_row(png_bytep row, size_t rowbytes, unsigned int y, int color_type,
+ int bit_depth, png_const_bytep gamma_table, double conv,
+ unsigned int *colors, int small)
+{
+ int filters = 0; /* file *MASK*, 0 means the default, not NONE */
+ png_uint_32 size_max =
+ image_size_of_type(color_type, bit_depth, colors, small)-1;
+ png_uint_32 depth_max = (1U << bit_depth)-1; /* up to 65536 */
+
+ if (colors[0] == 0) if (small)
+ {
+ unsigned int pixel_depth = pixel_depth_of_type(color_type, bit_depth);
+
+ /* For pixel depths less than 16 generate a single row containing all the
+ * possible pixel values. For 16 generate all 65536 byte pair
+ * combinations in a 256x256 pixel array.
+ */
+ switch (pixel_depth)
+ {
+ case 1:
+ assert(y == 0 && rowbytes == 1 && size_max == 1);
+ row[0] = 0x6CU; /* binary: 01101100, only top 2 bits used */
+ filters = PNG_FILTER_NONE;
+ break;
+
+ case 2:
+ assert(y == 0 && rowbytes == 1 && size_max == 3);
+ row[0] = 0x1BU; /* binary 00011011, all bits used */
+ filters = PNG_FILTER_NONE;
+ break;
+
+ case 4:
+ assert(y == 0 && rowbytes == 8 && size_max == 15);
+ row[0] = 0x01U;
+ row[1] = 0x23U; /* SUB gives 0x22U for all following bytes */
+ row[2] = 0x45U;
+ row[3] = 0x67U;
+ row[4] = 0x89U;
+ row[5] = 0xABU;
+ row[6] = 0xCDU;
+ row[7] = 0xEFU;
+ filters = PNG_FILTER_SUB;
+ break;
+
+ case 8:
+ /* The row will have all the pixel values in order starting with
+ * '1', the SUB filter will change every byte into '1' (including
+ * the last, which generates pixel value '0'). Since the SUB filter
+ * has value 1 this should result in maximum compression.
+ */
+ assert(y == 0 && rowbytes == 256 && size_max == 255);
+ for (;;)
+ {
+ row[size_max] = 0xFFU & (size_max+1);
+ if (size_max == 0)
+ break;
+ --size_max;
+ }
+ filters = PNG_FILTER_SUB;
+ break;
+
+ case 16:
+ /* Rows are generated such that each row has a constant difference
+ * between the first and second byte of each pixel and so that the
+ * difference increases by 1 at each row. The rows start with the
+ * first byte value of 0 and the value increases to 255 across the
+ * row.
+ *
+ * The difference starts at 1, so the first row is:
+ *
+ * 0 1 1 2 2 3 3 4 ... 254 255 255 0
+ *
+ * This means that running the SUB filter on the first row produces:
+ *
+ * [SUB==1] 0 1 0 1 0 1...
+ *
+ * Then the difference is 2 on the next row, giving:
+ *
+ * 0 2 1 3 2 4 3 5 ... 254 0 255 1
+ *
+ * When the UP filter is run on this libpng produces:
+ *
+ * [UP ==2] 0 1 0 1 0 1...
+ *
+ * And so on for all the remain rows to the final two * rows:
+ *
+ * row 254: 0 255 1 0 2 1 3 2 4 3 ... 254 253 255 254
+ * row 255: 0 0 1 1 2 2 3 3 4 4 ... 254 254 255 255
+ */
+ assert(rowbytes == 512 && size_max == 255);
+ for (;;)
+ {
+ row[2*size_max ] = 0xFFU & size_max;
+ row[2*size_max+1] = 0xFFU & (size_max+y+1);
+ if (size_max == 0)
+ break;
+ --size_max;
+ }
+ /* The first row must include PNG_FILTER_UP so that libpng knows we
+ * need to keep it for the following row:
+ */
+ filters = (y == 0 ? PNG_FILTER_SUB+PNG_FILTER_UP : PNG_FILTER_UP);
+ break;
+
+ case 24:
+ case 32:
+ case 48:
+ case 64:
+ /* The rows are filled by an alogorithm similar to the above, in the
+ * first row pixel bytes are all equal, increasing from 0 by 1 for
+ * each pixel. In the second row the bytes within a pixel are
+ * incremented 1,3,5,7,... from the previous row byte. Using an odd
+ * number ensures all the possible byte values are used.
+ */
+ assert(size_max == 255 && rowbytes == 256*(pixel_depth>>3));
+ pixel_depth >>= 3; /* now in bytes */
+ while (rowbytes > 0)
+ {
+ const size_t pixel_index = --rowbytes/pixel_depth;
+
+ if (y == 0)
+ row[rowbytes] = 0xFFU & pixel_index;
+
+ else
+ {
+ const size_t byte_offset =
+ rowbytes - pixel_index * pixel_depth;
+
+ row[rowbytes] =
+ 0xFFU & (pixel_index + (byte_offset * 2*y) + 1);
+ }
+ }
+ filters = (y == 0 ? PNG_FILTER_SUB+PNG_FILTER_UP : PNG_FILTER_UP);
+ break;
+
+ default:
+ assert(0/*NOT REACHED*/);
+ }
+ }
+
+ else switch (channels_of_type(color_type))
+ {
+ /* 1 channel: a square image with a diamond, the least luminous colors are on
+ * the edge of the image, the most luminous in the center.
+ */
+ case 1:
+ {
+ png_uint_32 x;
+ png_uint_32 base = 2*size_max - abs(2*y-size_max);
+
+ for (x=0; x<=size_max; ++x)
+ {
+ png_uint_32 luma = base - abs(2*x-size_max);
+
+ /* 'luma' is now in the range 0..2*size_max, we need
+ * 0..depth_max
+ */
+ luma = (luma*depth_max + size_max) / (2*size_max);
+ set_value(row, rowbytes, x, bit_depth, luma, gamma_table, conv);
+ }
+ }
+ break;
+
+ /* 2 channels: the color channel increases in luminosity from top to bottom,
+ * the alpha channel increases in opacity from left to right.
+ */
+ case 2:
+ {
+ png_uint_32 alpha = (depth_max * y * 2 + size_max) / (2 * size_max);
+ png_uint_32 x;
+
+ for (x=0; x<=size_max; ++x)
+ {
+ set_value(row, rowbytes, 2*x, bit_depth,
+ (depth_max * x * 2 + size_max) / (2 * size_max), gamma_table,
+ conv);
+ set_value(row, rowbytes, 2*x+1, bit_depth, alpha, gamma_table,
+ conv);
+ }
+ }
+ break;
+
+ /* 3 channels: linear combinations of, from the top-left corner clockwise,
+ * black, green, white, red.
+ */
+ case 3:
+ {
+ /* x0: the black->red scale (the value of the red component) at the
+ * start of the row (blue and green are 0).
+ * x1: the green->white scale (the value of the red and blue
+ * components at the end of the row; green is depth_max).
+ */
+ png_uint_32 Y = (depth_max * y * 2 + size_max) / (2 * size_max);
+ png_uint_32 x;
+
+ /* Interpolate x/depth_max from start to end:
+ *
+ * start end difference
+ * red: Y Y 0
+ * green: 0 depth_max depth_max
+ * blue: 0 Y Y
+ */
+ for (x=0; x<=size_max; ++x)
+ {
+ set_value(row, rowbytes, 3*x+0, bit_depth, /* red */ Y,
+ gamma_table, conv);
+ set_value(row, rowbytes, 3*x+1, bit_depth, /* green */
+ (depth_max * x * 2 + size_max) / (2 * size_max),
+ gamma_table, conv);
+ set_value(row, rowbytes, 3*x+2, bit_depth, /* blue */
+ (Y * x * 2 + size_max) / (2 * size_max),
+ gamma_table, conv);
+ }
+ }
+ break;
+
+ /* 4 channels: linear combinations of, from the top-left corner clockwise,
+ * transparent, red, green, blue.
+ */
+ case 4:
+ {
+ /* x0: the transparent->blue scale (the value of the blue and alpha
+ * components) at the start of the row (red and green are 0).
+ * x1: the red->green scale (the value of the red and green
+ * components at the end of the row; blue is 0 and alpha is
+ * depth_max).
+ */
+ png_uint_32 Y = (depth_max * y * 2 + size_max) / (2 * size_max);
+ png_uint_32 x;
+
+ /* Interpolate x/depth_max from start to end:
+ *
+ * start end difference
+ * red: 0 depth_max-Y depth_max-Y
+ * green: 0 Y Y
+ * blue: Y 0 -Y
+ * alpha: Y depth_max depth_max-Y
+ */
+ for (x=0; x<=size_max; ++x)
+ {
+ set_value(row, rowbytes, 4*x+0, bit_depth, /* red */
+ ((depth_max-Y) * x * 2 + size_max) / (2 * size_max),
+ gamma_table, conv);
+ set_value(row, rowbytes, 4*x+1, bit_depth, /* green */
+ (Y * x * 2 + size_max) / (2 * size_max),
+ gamma_table, conv);
+ set_value(row, rowbytes, 4*x+2, bit_depth, /* blue */
+ Y - (Y * x * 2 + size_max) / (2 * size_max),
+ gamma_table, conv);
+ set_value(row, rowbytes, 4*x+3, bit_depth, /* alpha */
+ Y + ((depth_max-Y) * x * 2 + size_max) / (2 * size_max),
+ gamma_table, conv);
+ }
+ }
+ break;
+
+ default:
+ fprintf(stderr, "makepng: internal bad channel count\n");
+ exit(2);
+ }
+
+ else if (color_type & PNG_COLOR_MASK_PALETTE)
+ {
+ /* Palette with fixed color: the image rows are all 0 and the image width
+ * is 16.
+ */
+ memset(row, 0, rowbytes);
+ }
+
+ else if (colors[0] == channels_of_type(color_type))
+ switch (channels_of_type(color_type))
+ {
+ case 1:
+ {
+ const png_uint_32 luma = colors[1];
+ png_uint_32 x;
+
+ for (x=0; x<=size_max; ++x)
+ set_value(row, rowbytes, x, bit_depth, luma, gamma_table,
+ conv);
+ }
+ break;
+
+ case 2:
+ {
+ const png_uint_32 luma = colors[1];
+ const png_uint_32 alpha = colors[2];
+ png_uint_32 x;
+
+ for (x=0; x<size_max; ++x)
+ {
+ set_value(row, rowbytes, 2*x, bit_depth, luma, gamma_table,
+ conv);
+ set_value(row, rowbytes, 2*x+1, bit_depth, alpha, gamma_table,
+ conv);
+ }
+ }
+ break;
+
+ case 3:
+ {
+ const png_uint_32 red = colors[1];
+ const png_uint_32 green = colors[2];
+ const png_uint_32 blue = colors[3];
+ png_uint_32 x;
+
+ for (x=0; x<=size_max; ++x)
+ {
+ set_value(row, rowbytes, 3*x+0, bit_depth, red, gamma_table,
+ conv);
+ set_value(row, rowbytes, 3*x+1, bit_depth, green, gamma_table,
+ conv);
+ set_value(row, rowbytes, 3*x+2, bit_depth, blue, gamma_table,
+ conv);
+ }
+ }
+ break;
+
+ case 4:
+ {
+ const png_uint_32 red = colors[1];
+ const png_uint_32 green = colors[2];
+ const png_uint_32 blue = colors[3];
+ const png_uint_32 alpha = colors[4];
+ png_uint_32 x;
+
+ for (x=0; x<=size_max; ++x)
+ {
+ set_value(row, rowbytes, 4*x+0, bit_depth, red, gamma_table,
+ conv);
+ set_value(row, rowbytes, 4*x+1, bit_depth, green, gamma_table,
+ conv);
+ set_value(row, rowbytes, 4*x+2, bit_depth, blue, gamma_table,
+ conv);
+ set_value(row, rowbytes, 4*x+3, bit_depth, alpha, gamma_table,
+ conv);
+ }
+ }
+ break;
+
+ default:
+ fprintf(stderr, "makepng: internal bad channel count\n");
+ exit(2);
+ }
+
+ else
+ {
+ fprintf(stderr,
+ "makepng: --color: count(%u) does not match channels(%u)\n",
+ colors[0], channels_of_type(color_type));
+ exit(1);
+ }
+
+ return filters;
+}
+
+
+static void PNGCBAPI
+makepng_warning(png_structp png_ptr, png_const_charp message)
+{
+ const char **ep = png_get_error_ptr(png_ptr);
+ const char *name;
+
+ if (ep != NULL && *ep != NULL)
+ name = *ep;
+
+ else
+ name = "makepng";
+
+ fprintf(stderr, "%s: warning: %s\n", name, message);
+}
+
+static void PNGCBAPI
+makepng_error(png_structp png_ptr, png_const_charp message)
+{
+ makepng_warning(png_ptr, message);
+ png_longjmp(png_ptr, 1);
+}
+
+static int /* 0 on success, else an error code */
+write_png(const char **name, FILE *fp, int color_type, int bit_depth,
+ volatile png_fixed_point gamma, chunk_insert * volatile insert,
+ unsigned int filters, unsigned int *colors, int small, int tRNS)
+{
+ png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
+ name, makepng_error, makepng_warning);
+ volatile png_infop info_ptr = NULL;
+ volatile png_bytep row = NULL;
+
+ if (png_ptr == NULL)
+ {
+ fprintf(stderr, "makepng: OOM allocating write structure\n");
+ return 1;
+ }
+
+ if (setjmp(png_jmpbuf(png_ptr)))
+ {
+ png_structp nv_ptr = png_ptr;
+ png_infop nv_info = info_ptr;
+
+ png_ptr = NULL;
+ info_ptr = NULL;
+ png_destroy_write_struct(&nv_ptr, &nv_info);
+ if (row != NULL) free(row);
+ return 1;
+ }
+
+ /* Allow benign errors so that we can write PNGs with errors */
+ png_set_benign_errors(png_ptr, 1/*allowed*/);
+
+ /* Max out the text compression level in an attempt to make the license
+ * small. If --small then do the same for the IDAT.
+ */
+ if (small)
+ png_set_compression_level(png_ptr, Z_BEST_COMPRESSION);
+
+ png_set_text_compression_level(png_ptr, Z_BEST_COMPRESSION);
+
+ png_init_io(png_ptr, fp);
+
+ info_ptr = png_create_info_struct(png_ptr);
+ if (info_ptr == NULL)
+ png_error(png_ptr, "OOM allocating info structure");
+
+ {
+ const unsigned int size =
+ image_size_of_type(color_type, bit_depth, colors, small);
+ unsigned int ysize;
+ png_fixed_point real_gamma = 45455; /* For sRGB */
+ png_byte gamma_table[256];
+ double conv;
+
+ /* Normally images are square, but with 'small' we want to simply generate
+ * all the pixel values, or all that we reasonably can:
+ */
+ if (small)
+ {
+ const unsigned int pixel_depth =
+ pixel_depth_of_type(color_type, bit_depth);
+
+ if (pixel_depth <= 8U)
+ {
+ assert(size == (1U<<pixel_depth));
+ ysize = 1U;
+ }
+
+ else
+ {
+ assert(size == 256U);
+ ysize = 256U;
+ }
+ }
+
+ else
+ ysize = size;
+
+ /* This function uses the libpng values used on read to carry extra
+ * information about the gamma:
+ */
+ if (gamma == PNG_GAMMA_MAC_18)
+ gamma = 65909;
+
+ else if (gamma > 0 && gamma < 1000)
+ gamma = PNG_FP_1;
+
+ if (gamma > 0)
+ real_gamma = gamma;
+
+ {
+ unsigned int i;
+
+ if (real_gamma == 45455) for (i=0; i<256; ++i)
+ {
+ gamma_table[i] = (png_byte)i;
+ conv = 1.;
+ }
+
+ else
+ {
+ /* Convert 'i' from sRGB (45455) to real_gamma, this makes
+ * the images look the same regardless of the gAMA chunk.
+ */
+ conv = real_gamma;
+ conv /= 45455;
+
+ gamma_table[0] = 0;
+
+ for (i=1; i<255; ++i)
+ gamma_table[i] = floorb(pow(i/255.,conv) * 255 + .5);
+
+ gamma_table[255] = 255;
+ }
+ }
+
+ png_set_IHDR(png_ptr, info_ptr, size, ysize, bit_depth, color_type,
+ PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+
+ if (color_type & PNG_COLOR_MASK_PALETTE)
+ {
+ int npalette;
+ png_color palette[256];
+ png_byte trans[256];
+
+ npalette = generate_palette(palette, trans, bit_depth, gamma_table,
+ colors);
+ png_set_PLTE(png_ptr, info_ptr, palette, npalette);
+
+ if (tRNS)
+ png_set_tRNS(png_ptr, info_ptr, trans, npalette-1,
+ NULL/*transparent color*/);
+
+ /* Reset gamma_table to prevent the image rows being changed */
+ for (npalette=0; npalette<256; ++npalette)
+ gamma_table[npalette] = (png_byte)npalette;
+ }
+
+ else if (tRNS)
+ {
+ png_color_16 col;
+
+ col.red = col.green = col.blue = col.gray =
+ 0x0101U & ((1U<<bit_depth)-1U);
+ col.index = 0U;
+ png_set_tRNS(png_ptr, info_ptr, NULL/*trans*/, 1U, &col);
+ }
+
+ if (gamma == PNG_DEFAULT_sRGB)
+ png_set_sRGB(png_ptr, info_ptr, PNG_sRGB_INTENT_ABSOLUTE);
+
+ else if (gamma > 0) /* Else don't set color space information */
+ {
+ png_set_gAMA_fixed(png_ptr, info_ptr, real_gamma);
+
+ /* Just use the sRGB values here. */
+ png_set_cHRM_fixed(png_ptr, info_ptr,
+ /* color x y */
+ /* white */ 31270, 32900,
+ /* red */ 64000, 33000,
+ /* green */ 30000, 60000,
+ /* blue */ 15000, 6000
+ );
+ }
+
+ /* Insert extra information. */
+ while (insert != NULL)
+ {
+ insert->insert(png_ptr, info_ptr, insert->nparams, insert->parameters);
+ insert = insert->next;
+ }
+
+ /* Write the file header. */
+ png_write_info(png_ptr, info_ptr);
+
+ /* Restrict the filters */
+ png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE, filters);
+
+ {
+# ifdef PNG_WRITE_INTERLACING_SUPPORTED
+ int passes = png_set_interlace_handling(png_ptr);
+# else /* !WRITE_INTERLACING */
+ int passes = 1;
+# endif /* !WRITE_INTERLACING */
+ int pass;
+ png_size_t rowbytes = png_get_rowbytes(png_ptr, info_ptr);
+
+ row = malloc(rowbytes);
+
+ if (row == NULL)
+ png_error(png_ptr, "OOM allocating row buffer");
+
+ for (pass = 0; pass < passes; ++pass)
+ {
+ unsigned int y;
+
+ for (y=0; y<ysize; ++y)
+ {
+ unsigned int row_filters =
+ generate_row(row, rowbytes, y, color_type, bit_depth,
+ gamma_table, conv, colors, small);
+
+ if (row_filters != 0 && filters == PNG_ALL_FILTERS)
+ png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE, row_filters);
+
+ png_write_row(png_ptr, row);
+ }
+ }
+ }
+ }
+
+ /* Finish writing the file. */
+ png_write_end(png_ptr, info_ptr);
+
+ {
+ png_structp nv_ptr = png_ptr;
+ png_infop nv_info = info_ptr;
+
+ png_ptr = NULL;
+ info_ptr = NULL;
+ png_destroy_write_struct(&nv_ptr, &nv_info);
+ }
+ free(row);
+ return 0;
+}
+
+
+static size_t
+load_file(png_const_charp name, png_bytepp result)
+{
+ FILE *fp = tmpfile();
+
+ if (fp != NULL)
+ {
+ FILE *ip = fopen(name, "rb");
+
+ if (ip != NULL)
+ {
+ size_t total = 0;
+ int ch;
+
+ for (;;)
+ {
+ ch = getc(ip);
+ if (ch == EOF) break;
+ putc(ch, fp);
+ ++total;
+ }
+
+ if (ferror(ip))
+ {
+ perror(name);
+ fprintf(stderr, "%s: read error\n", name);
+ (void)fclose(ip);
+ }
+
+ else
+ {
+ (void)fclose(ip);
+
+ if (ferror(fp))
+ {
+ perror("temporary file");
+ fprintf(stderr, "temporary file write error\n");
+ }
+
+ else
+ {
+ rewind(fp);
+
+ if (total > 0)
+ {
+ /* Round up to a multiple of 4 here to allow an iCCP profile
+ * to be padded to a 4x boundary.
+ */
+ png_bytep data = malloc((total+3)&~3);
+
+ if (data != NULL)
+ {
+ size_t new_size = 0;
+
+ for (;;)
+ {
+ ch = getc(fp);
+ if (ch == EOF) break;
+ data[new_size++] = (png_byte)ch;
+ }
+
+ if (ferror(fp) || new_size != total)
+ {
+ perror("temporary file");
+ fprintf(stderr, "temporary file read error\n");
+ free(data);
+ }
+
+ else
+ {
+ (void)fclose(fp);
+ *result = data;
+ return total;
+ }
+ }
+
+ else
+ fprintf(stderr, "%s: out of memory loading file\n", name);
+ }
+
+ else
+ fprintf(stderr, "%s: empty file\n", name);
+ }
+ }
+ }
+
+ else
+ {
+ perror(name);
+ fprintf(stderr, "%s: open failed\n", name);
+ }
+
+ fclose(fp);
+ }
+
+ else
+ fprintf(stderr, "makepng: %s: could not open temporary file\n", name);
+
+ exit(1);
+ return 0;
+}
+
+static png_size_t
+load_fake(png_charp param, png_bytepp profile)
+{
+ char *endptr = NULL;
+ uint64_t size = strtoull(param, &endptr, 0/*base*/);
+
+ /* The 'fake' format is <number>*[string] */
+ if (endptr != NULL && *endptr == '*')
+ {
+ size_t len = strlen(++endptr);
+ size_t result = (size_t)size;
+
+ if (len == 0) len = 1; /* capture the terminating '\0' */
+
+ /* Now repeat that string to fill 'size' bytes. */
+ if (result == size && (*profile = malloc(result)) != NULL)
+ {
+ png_bytep out = *profile;
+
+ if (len == 1)
+ memset(out, *endptr, result);
+
+ else
+ {
+ while (size >= len)
+ {
+ memcpy(out, endptr, len);
+ out += len;
+ size -= len;
+ }
+ memcpy(out, endptr, size);
+ }
+
+ return result;
+ }
+
+ else
+ {
+ fprintf(stderr, "%s: size exceeds system limits\n", param);
+ exit(1);
+ }
+ }
+
+ return 0;
+}
+
+static void
+check_param_count(int nparams, int expect)
+{
+ if (nparams != expect)
+ {
+ fprintf(stderr, "bad parameter count (internal error)\n");
+ exit(1);
+ }
+}
+
+static void
+insert_iCCP(png_structp png_ptr, png_infop info_ptr, int nparams,
+ png_charpp params)
+{
+ png_bytep profile = NULL;
+ png_uint_32 proflen = 0;
+ int result;
+
+ check_param_count(nparams, 2);
+
+ switch (params[1][0])
+ {
+ case '<':
+ {
+ png_size_t filelen = load_file(params[1]+1, &profile);
+ if (filelen > 0xfffffffc) /* Maximum profile length */
+ {
+ fprintf(stderr, "%s: file too long (%lu) for an ICC profile\n",
+ params[1]+1, (unsigned long)filelen);
+ exit(1);
+ }
+
+ proflen = (png_uint_32)filelen;
+ }
+ break;
+
+ case '0': case '1': case '2': case '3': case '4':
+ case '5': case '6': case '7': case '8': case '9':
+ {
+ png_size_t fake_len = load_fake(params[1], &profile);
+
+ if (fake_len > 0) /* else a simple parameter */
+ {
+ if (fake_len > 0xffffffff) /* Maximum profile length */
+ {
+ fprintf(stderr,
+ "%s: fake data too long (%lu) for an ICC profile\n",
+ params[1], (unsigned long)fake_len);
+ exit(1);
+ }
+ proflen = (png_uint_32)(fake_len & ~3U);
+ /* Always fix up the profile length. */
+ png_save_uint_32(profile, proflen);
+ break;
+ }
+ }
+
+ default:
+ fprintf(stderr, "--insert iCCP \"%s\": unrecognized\n", params[1]);
+ fprintf(stderr, " use '<' to read a file: \"<filename\"\n");
+ exit(1);
+ }
+
+ result = 1;
+
+ if (proflen & 3)
+ {
+ fprintf(stderr,
+ "makepng: --insert iCCP %s: profile length made a multiple of 4\n",
+ params[1]);
+
+ /* load_file allocates extra space for this padding, the ICC spec requires
+ * padding with zero bytes.
+ */
+ while (proflen & 3)
+ profile[proflen++] = 0;
+ }
+
+ if (profile != NULL && proflen > 3)
+ {
+ png_uint_32 prof_header = png_get_uint_32(profile);
+
+ if (prof_header != proflen)
+ {
+ fprintf(stderr, "--insert iCCP %s: profile length field wrong:\n",
+ params[1]);
+ fprintf(stderr, " actual %lu, recorded value %lu (corrected)\n",
+ (unsigned long)proflen, (unsigned long)prof_header);
+ png_save_uint_32(profile, proflen);
+ }
+ }
+
+ if (result && profile != NULL && proflen >=4)
+ png_set_iCCP(png_ptr, info_ptr, params[0], PNG_COMPRESSION_TYPE_BASE,
+ profile, proflen);
+
+ if (profile)
+ free(profile);
+
+ if (!result)
+ exit(1);
+}
+
+static void
+clear_text(png_text *text, png_charp keyword)
+{
+ text->compression = -1; /* none */
+ text->key = keyword;
+ text->text = NULL;
+ text->text_length = 0; /* libpng calculates this */
+ text->itxt_length = 0; /* libpng calculates this */
+ text->lang = NULL;
+ text->lang_key = NULL;
+}
+
+static void
+set_text(png_structp png_ptr, png_infop info_ptr, png_textp text,
+ png_charp param)
+{
+ switch (param[0])
+ {
+ case '<':
+ {
+ png_bytep file = NULL;
+
+ text->text_length = load_file(param+1, &file);
+ text->text = (png_charp)file;
+ }
+ break;
+
+ case '0': case '1': case '2': case '3': case '4':
+ case '5': case '6': case '7': case '8': case '9':
+ {
+ png_bytep data = NULL;
+ png_size_t fake_len = load_fake(param, &data);
+
+ if (fake_len > 0) /* else a simple parameter */
+ {
+ text->text_length = fake_len;
+ text->text = (png_charp)data;
+ break;
+ }
+ }
+
+ default:
+ text->text = param;
+ break;
+ }
+
+ png_set_text(png_ptr, info_ptr, text, 1);
+
+ if (text->text != param)
+ free(text->text);
+}
+
+static void
+insert_tEXt(png_structp png_ptr, png_infop info_ptr, int nparams,
+ png_charpp params)
+{
+ png_text text;
+
+ check_param_count(nparams, 2);
+ clear_text(&text, params[0]);
+ set_text(png_ptr, info_ptr, &text, params[1]);
+}
+
+static void
+insert_zTXt(png_structp png_ptr, png_infop info_ptr, int nparams,
+ png_charpp params)
+{
+ png_text text;
+
+ check_param_count(nparams, 2);
+ clear_text(&text, params[0]);
+ text.compression = 0; /* deflate */
+ set_text(png_ptr, info_ptr, &text, params[1]);
+}
+
+static void
+insert_iTXt(png_structp png_ptr, png_infop info_ptr, int nparams,
+ png_charpp params)
+{
+ png_text text;
+
+ check_param_count(nparams, 4);
+ clear_text(&text, params[0]);
+ text.compression = 2; /* iTXt + deflate */
+ text.lang = params[1];/* language tag */
+ text.lang_key = params[2]; /* translated keyword */
+ set_text(png_ptr, info_ptr, &text, params[3]);
+}
+
+static void
+insert_hIST(png_structp png_ptr, png_infop info_ptr, int nparams,
+ png_charpp params)
+{
+ int i;
+ png_uint_16 freq[256];
+
+ /* libpng takes the count from the PLTE count; we don't check it here but we
+ * do set the array to 0 for unspecified entries.
+ */
+ memset(freq, 0, sizeof freq);
+ for (i=0; i<nparams; ++i)
+ {
+ char *endptr = NULL;
+ unsigned long int l = strtoul(params[i], &endptr, 0/*base*/);
+
+ if (params[i][0] && *endptr == 0 && l <= 65535)
+ freq[i] = (png_uint_16)l;
+
+ else
+ {
+ fprintf(stderr, "hIST[%d]: %s: invalid frequency\n", i, params[i]);
+ exit(1);
+ }
+ }
+
+ png_set_hIST(png_ptr, info_ptr, freq);
+}
+
+static png_byte
+bval(png_const_structrp png_ptr, png_charp param, unsigned int maxval)
+{
+ char *endptr = NULL;
+ unsigned long int l = strtoul(param, &endptr, 0/*base*/);
+
+ if (param[0] && *endptr == 0 && l <= maxval)
+ return (png_byte)l;
+
+ else
+ png_error(png_ptr, "sBIT: invalid sBIT value");
+}
+
+static void
+insert_sBIT(png_structp png_ptr, png_infop info_ptr, int nparams,
+ png_charpp params)
+{
+ const int ct = png_get_color_type(png_ptr, info_ptr);
+ const int c = (ct & PNG_COLOR_MASK_COLOR ? 3 : 1) +
+ (ct & PNG_COLOR_MASK_ALPHA ? 1 : 0);
+ const unsigned int maxval =
+ ct & PNG_COLOR_MASK_PALETTE ? 8U : png_get_bit_depth(png_ptr, info_ptr);
+ png_color_8 sBIT;
+
+ if (nparams != c)
+ png_error(png_ptr, "sBIT: incorrect parameter count");
+
+ if (ct & PNG_COLOR_MASK_COLOR)
+ {
+ sBIT.red = bval(png_ptr, params[0], maxval);
+ sBIT.green = bval(png_ptr, params[1], maxval);
+ sBIT.blue = bval(png_ptr, params[2], maxval);
+ sBIT.gray = 42;
+ }
+
+ else
+ {
+ sBIT.red = sBIT.green = sBIT.blue = 42;
+ sBIT.gray = bval(png_ptr, params[0], maxval);
+ }
+
+ if (ct & PNG_COLOR_MASK_ALPHA)
+ sBIT.alpha = bval(png_ptr, params[nparams-1], maxval);
+
+ else
+ sBIT.alpha = 42;
+
+ png_set_sBIT(png_ptr, info_ptr, &sBIT);
+}
+
+#if 0
+static void
+insert_sPLT(png_structp png_ptr, png_infop info_ptr, int nparams, png_charpp params)
+{
+ fprintf(stderr, "insert sPLT: NYI\n");
+}
+#endif
+
+static int
+find_parameters(png_const_charp what, png_charp param, png_charp *list,
+ int nparams)
+{
+ /* Parameters are separated by '\n' or ':' characters, up to nparams are
+ * accepted (more is an error) and the number found is returned.
+ */
+ int i;
+ for (i=0; *param && i<nparams; ++i)
+ {
+ list[i] = param;
+ while (*++param) if (*param == '\n' || *param == ':')
+ {
+ *param++ = 0; /* Terminate last parameter */
+ break; /* And start a new one. */
+ }
+ }
+
+ if (*param)
+ {
+ fprintf(stderr, "--insert %s: too many parameters (%s)\n", what, param);
+ exit(1);
+ }
+
+ list[i] = NULL; /* terminates list */
+ return i; /* number of parameters filled in */
+}
+
+static void
+bad_parameter_count(png_const_charp what, int nparams)
+{
+ fprintf(stderr, "--insert %s: bad parameter count %d\n", what, nparams);
+ exit(1);
+}
+
+static chunk_insert *
+make_insert(png_const_charp what,
+ void (*insert)(png_structp, png_infop, int, png_charpp),
+ int nparams, png_charpp list)
+{
+ int i;
+ chunk_insert *cip;
+
+ cip = malloc(offsetof(chunk_insert,parameters) +
+ nparams * sizeof (png_charp));
+
+ if (cip == NULL)
+ {
+ fprintf(stderr, "--insert %s: out of memory allocating %d parameters\n",
+ what, nparams);
+ exit(1);
+ }
+
+ cip->next = NULL;
+ cip->insert = insert;
+ cip->nparams = nparams;
+ for (i=0; i<nparams; ++i)
+ cip->parameters[i] = list[i];
+
+ return cip;
+}
+
+static chunk_insert *
+find_insert(png_const_charp what, png_charp param)
+{
+ png_uint_32 chunk = 0;
+ png_charp parameter_list[1024];
+ int i, nparams;
+
+ /* Assemble the chunk name */
+ for (i=0; i<4; ++i)
+ {
+ char ch = what[i];
+
+ if ((ch >= 65 && ch <= 90) || (ch >= 97 && ch <= 122))
+ chunk = (chunk << 8) + what[i];
+
+ else
+ break;
+ }
+
+ if (i < 4 || what[4] != 0)
+ {
+ fprintf(stderr, "makepng --insert \"%s\": invalid chunk name\n", what);
+ exit(1);
+ }
+
+ /* Assemble the parameter list. */
+ nparams = find_parameters(what, param, parameter_list, 1024);
+
+# define CHUNK(a,b,c,d) (((a)<<24)+((b)<<16)+((c)<<8)+(d))
+
+ switch (chunk)
+ {
+ case CHUNK(105,67,67,80): /* iCCP */
+ if (nparams == 2)
+ return make_insert(what, insert_iCCP, nparams, parameter_list);
+ break;
+
+ case CHUNK(116,69,88,116): /* tEXt */
+ if (nparams == 2)
+ return make_insert(what, insert_tEXt, nparams, parameter_list);
+ break;
+
+ case CHUNK(122,84,88,116): /* zTXt */
+ if (nparams == 2)
+ return make_insert(what, insert_zTXt, nparams, parameter_list);
+ break;
+
+ case CHUNK(105,84,88,116): /* iTXt */
+ if (nparams == 4)
+ return make_insert(what, insert_iTXt, nparams, parameter_list);
+ break;
+
+ case CHUNK(104,73,83,84): /* hIST */
+ if (nparams <= 256)
+ return make_insert(what, insert_hIST, nparams, parameter_list);
+ break;
+
+ case CHUNK(115,66,73,84): /* sBIT */
+ if (nparams <= 4)
+ return make_insert(what, insert_sBIT, nparams, parameter_list);
+ break;
+
+#if 0
+ case CHUNK(115,80,76,84): /* sPLT */
+ return make_insert(what, insert_sPLT, nparams, parameter_list);
+#endif
+
+ default:
+ fprintf(stderr, "makepng --insert \"%s\": unrecognized chunk name\n",
+ what);
+ exit(1);
+ }
+
+ bad_parameter_count(what, nparams);
+ return NULL;
+}
+
+/* This is necessary because libpng expects writeable strings for things like
+ * text chunks (maybe this should be fixed...)
+ */
+static png_charp
+strstash(png_const_charp foo)
+{
+ /* The program indicates a memory allocation error by crashing, this is by
+ * design.
+ */
+ if (foo != NULL)
+ {
+ png_charp bar = malloc(strlen(foo)+1);
+ return strcpy(bar, foo);
+ }
+
+ return NULL;
+}
+
+static png_charp
+strstash_list(const png_const_charp *text)
+{
+ size_t foo = 0;
+ png_charp result, bar;
+ const png_const_charp *line = text;
+
+ while (*line != NULL)
+ foo += strlen(*line++);
+
+ result = bar = malloc(foo+1);
+
+ line = text;
+ while (*line != NULL)
+ {
+ foo = strlen(*line);
+ memcpy(bar, *line++, foo);
+ bar += foo;
+ }
+
+ *bar = 0;
+ return result;
+}
+
+/* These are used to insert Copyright and Licence fields, they allow the text to
+ * have \n unlike the --insert option.
+ */
+static chunk_insert *
+add_tEXt(const char *key, const png_const_charp *text)
+{
+ static char what[5] = { 116, 69, 88, 116, 0 };
+ png_charp parameter_list[3];
+
+ parameter_list[0] = strstash(key);
+ parameter_list[1] = strstash_list(text);
+ parameter_list[2] = NULL;
+
+ return make_insert(what, insert_tEXt, 2, parameter_list);
+}
+
+static chunk_insert *
+add_iTXt(const char *key, const char *language, const char *language_key,
+ const png_const_charp *text)
+{
+ static char what[5] = { 105, 84, 88, 116, 0 };
+ png_charp parameter_list[5];
+
+ parameter_list[0] = strstash(key);
+ parameter_list[1] = strstash(language);
+ parameter_list[2] = strstash(language_key);
+ parameter_list[3] = strstash_list(text);
+ parameter_list[4] = NULL;
+
+ return make_insert(what, insert_iTXt, 4, parameter_list);
+}
+
+/* This is a not-very-good parser for a sequence of numbers (including 0). It
+ * doesn't accept some apparently valid things, but it accepts all the sensible
+ * combinations.
+ */
+static void
+parse_color(char *arg, unsigned int *colors)
+{
+ unsigned int ncolors = 0;
+
+ while (*arg && ncolors < 4)
+ {
+ char *ep = arg;
+
+ unsigned long ul = strtoul(arg, &ep, 0);
+
+ if (ul > 65535)
+ {
+ fprintf(stderr, "makepng --color=...'%s': too big\n", arg);
+ exit(1);
+ }
+
+ if (ep == arg)
+ {
+ fprintf(stderr, "makepng --color=...'%s': not a valid color\n", arg);
+ exit(1);
+ }
+
+ if (*ep) ++ep; /* skip a separator */
+ arg = ep;
+
+ colors[++ncolors] = (unsigned int)ul; /* checked above */
+ }
+
+ if (*arg)
+ {
+ fprintf(stderr, "makepng --color=...'%s': too many values\n", arg);
+ exit(1);
+ }
+
+ *colors = ncolors;
+}
+
+int
+main(int argc, char **argv)
+{
+ FILE *fp = stdout;
+ const char *file_name = NULL;
+ int color_type = 8; /* invalid */
+ int bit_depth = 32; /* invalid */
+ int small = 0; /* make full size images */
+ int tRNS = 0; /* don't output a tRNS chunk */
+ unsigned int colors[5];
+ unsigned int filters = PNG_ALL_FILTERS;
+ png_fixed_point gamma = 0; /* not set */
+ chunk_insert *head_insert = NULL;
+ chunk_insert **insert_ptr = &head_insert;
+
+ memset(colors, 0, sizeof colors);
+
+ while (--argc > 0)
+ {
+ char *arg = *++argv;
+
+ if (strcmp(arg, "--small") == 0)
+ {
+ small = 1;
+ continue;
+ }
+
+ if (strcmp(arg, "--tRNS") == 0)
+ {
+ tRNS = 1;
+ continue;
+ }
+
+ if (strcmp(arg, "--sRGB") == 0)
+ {
+ gamma = PNG_DEFAULT_sRGB;
+ continue;
+ }
+
+ if (strcmp(arg, "--linear") == 0)
+ {
+ gamma = PNG_FP_1;
+ continue;
+ }
+
+ if (strcmp(arg, "--1.8") == 0)
+ {
+ gamma = PNG_GAMMA_MAC_18;
+ continue;
+ }
+
+ if (strcmp(arg, "--nofilters") == 0)
+ {
+ filters = PNG_FILTER_NONE;
+ continue;
+ }
+
+ if (strncmp(arg, "--color=", 8) == 0)
+ {
+ parse_color(arg+8, colors);
+ continue;
+ }
+
+ if (argc >= 3 && strcmp(arg, "--insert") == 0)
+ {
+ png_const_charp what = *++argv;
+ png_charp param = *++argv;
+ chunk_insert *new_insert;
+
+ argc -= 2;
+
+ new_insert = find_insert(what, param);
+
+ if (new_insert != NULL)
+ {
+ *insert_ptr = new_insert;
+ insert_ptr = &new_insert->next;
+ }
+
+ continue;
+ }
+
+ if (arg[0] == '-')
+ {
+ fprintf(stderr, "makepng: %s: invalid option\n", arg);
+ exit(1);
+ }
+
+ if (strcmp(arg, "palette") == 0)
+ {
+ color_type = PNG_COLOR_TYPE_PALETTE;
+ continue;
+ }
+
+ if (strncmp(arg, "gray", 4) == 0)
+ {
+ if (arg[4] == 0)
+ {
+ color_type = PNG_COLOR_TYPE_GRAY;
+ continue;
+ }
+
+ else if (strcmp(arg+4, "a") == 0 ||
+ strcmp(arg+4, "alpha") == 0 ||
+ strcmp(arg+4, "-alpha") == 0)
+ {
+ color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
+ continue;
+ }
+ }
+
+ if (strncmp(arg, "rgb", 3) == 0)
+ {
+ if (arg[3] == 0)
+ {
+ color_type = PNG_COLOR_TYPE_RGB;
+ continue;
+ }
+
+ else if (strcmp(arg+3, "a") == 0 ||
+ strcmp(arg+3, "alpha") == 0 ||
+ strcmp(arg+3, "-alpha") == 0)
+ {
+ color_type = PNG_COLOR_TYPE_RGB_ALPHA;
+ continue;
+ }
+ }
+
+ if (color_type == 8 && isdigit(arg[0]))
+ {
+ color_type = atoi(arg);
+ if (color_type < 0 || color_type > 6 || color_type == 1 ||
+ color_type == 5)
+ {
+ fprintf(stderr, "makepng: %s: not a valid color type\n", arg);
+ exit(1);
+ }
+
+ continue;
+ }
+
+ if (bit_depth == 32 && isdigit(arg[0]))
+ {
+ bit_depth = atoi(arg);
+ if (bit_depth <= 0 || bit_depth > 16 ||
+ (bit_depth & -bit_depth) != bit_depth)
+ {
+ fprintf(stderr, "makepng: %s: not a valid bit depth\n", arg);
+ exit(1);
+ }
+
+ continue;
+ }
+
+ if (argc == 1) /* It's the file name */
+ {
+ fp = fopen(arg, "wb");
+ if (fp == NULL)
+ {
+ fprintf(stderr, "%s: %s: could not open\n", arg, strerror(errno));
+ exit(1);
+ }
+
+ file_name = arg;
+ continue;
+ }
+
+ fprintf(stderr, "makepng: %s: unknown argument\n", arg);
+ exit(1);
+ } /* argument while loop */
+
+ if (color_type == 8 || bit_depth == 32)
+ {
+ fprintf(stderr, "usage: makepng [--small] [--sRGB|--linear|--1.8] "
+ "[--color=...] color-type bit-depth [file-name]\n"
+ " Make a test PNG file, by default writes to stdout.\n"
+ " Other options are available, UTSL.\n");
+ exit(1);
+ }
+
+ /* Check the colors */
+ {
+ const unsigned int lim = (color_type == PNG_COLOR_TYPE_PALETTE ? 255U :
+ (1U<<bit_depth)-1);
+ unsigned int i;
+
+ for (i=1; i<=colors[0]; ++i)
+ if (colors[i] > lim)
+ {
+ fprintf(stderr, "makepng: --color=...: %u out of range [0..%u]\n",
+ colors[i], lim);
+ exit(1);
+ }
+ }
+
+ /* small and colors are incomparible (will probably crash if both are used at
+ * the same time!)
+ */
+ if (small && colors[0] != 0)
+ {
+ fprintf(stderr, "makepng: --color --small: only one at a time!\n");
+ exit(1);
+ }
+
+ /* Restrict the filters for more speed to those we know are used for the
+ * generated images.
+ */
+ if (filters == PNG_ALL_FILTERS && !small/*small provides defaults*/)
+ {
+ if ((color_type & PNG_COLOR_MASK_PALETTE) != 0 || bit_depth < 8)
+ filters = PNG_FILTER_NONE;
+
+ else if (color_type & PNG_COLOR_MASK_COLOR) /* rgb */
+ {
+ if (bit_depth == 8)
+ filters &= ~(PNG_FILTER_NONE | PNG_FILTER_AVG);
+
+ else
+ filters = PNG_FILTER_SUB | PNG_FILTER_PAETH;
+ }
+
+ else /* gray 8 or 16-bit */
+ filters &= ~PNG_FILTER_NONE;
+ }
+
+ /* Insert standard copyright and licence text. */
+ {
+ static png_const_charp copyright[] =
+ {
+ COPYRIGHT, /* ISO-Latin-1 */
+ NULL
+ };
+ static png_const_charp licensing[] =
+ {
+ IMAGE_LICENSING, /* UTF-8 */
+ NULL
+ };
+
+ chunk_insert *new_insert;
+
+ new_insert = add_tEXt("Copyright", copyright);
+ if (new_insert != NULL)
+ {
+ *insert_ptr = new_insert;
+ insert_ptr = &new_insert->next;
+ }
+
+ new_insert = add_iTXt("Licensing", "en", NULL, licensing);
+ if (new_insert != NULL)
+ {
+ *insert_ptr = new_insert;
+ insert_ptr = &new_insert->next;
+ }
+ }
+
+ {
+ int ret = write_png(&file_name, fp, color_type, bit_depth, gamma,
+ head_insert, filters, colors, small, tRNS);
+
+ if (ret != 0 && file_name != NULL)
+ remove(file_name);
+
+ return ret;
+ }
+}
diff --git a/libpng/contrib/libtests/pngimage.c b/libpng/contrib/libtests/pngimage.c
new file mode 100644
index 0000000..442b2f4
--- /dev/null
+++ b/libpng/contrib/libtests/pngimage.c
@@ -0,0 +1,1687 @@
+/* pngimage.c
+ *
+ * Copyright (c) 2015 John Cunningham Bowler
+ *
+ * Last changed in libpng 1.6.20 [December 3, 2015]
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * Test the png_read_png and png_write_png interfaces. Given a PNG file load it
+ * using png_read_png and then write with png_write_png. Test all possible
+ * transforms.
+ */
+#include <stdarg.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <stdio.h>
+#include <assert.h>
+
+#if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H)
+# include <config.h>
+#endif
+
+/* Define the following to use this test against your installed libpng, rather
+ * than the one being built here:
+ */
+#ifdef PNG_FREESTANDING_TESTS
+# include <png.h>
+#else
+# include "../../png.h"
+#endif
+
+#ifndef PNG_SETJMP_SUPPORTED
+# include <setjmp.h> /* because png.h did *not* include this */
+#endif
+
+#if defined(PNG_INFO_IMAGE_SUPPORTED) && defined(PNG_SEQUENTIAL_READ_SUPPORTED)\
+ && (defined(PNG_READ_PNG_SUPPORTED) || PNG_LIBPNG_VER < 10700)
+/* If a transform is valid on both read and write this implies that if the
+ * transform is applied to read it must also be applied on write to produce
+ * meaningful data. This is because these transforms when performed on read
+ * produce data with a memory format that does not correspond to a PNG format.
+ *
+ * Most of these transforms are invertible; after applying the transform on
+ * write the result is the original PNG data that would have would have been
+ * read if no transform were applied.
+ *
+ * The exception is _SHIFT, which destroys the low order bits marked as not
+ * significant in a PNG with the sBIT chunk.
+ *
+ * The following table lists, for each transform, the conditions under which it
+ * is expected to do anything. Conditions are defined as follows:
+ *
+ * 1) Color mask bits required - simply a mask to AND with color_type; one of
+ * these must be present for the transform to fire, except that 0 means
+ * 'always'.
+ * 2) Color mask bits which must be absent - another mask - none of these must
+ * be present.
+ * 3) Bit depths - a mask of component bit depths for the transform to fire.
+ * 4) 'read' - the transform works in png_read_png.
+ * 5) 'write' - the transform works in png_write_png.
+ * 6) PNG_INFO_chunk; a mask of the chunks that must be present for the
+ * transform to fire. All must be present - the requirement is that
+ * png_get_valid() & mask == mask, so if mask is 0 there is no requirement.
+ *
+ * The condition refers to the original image state - if multiple transforms are
+ * used together it is possible to cause a transform that wouldn't fire on the
+ * original image to fire.
+ */
+static struct transform_info
+{
+ const char *name;
+ int transform;
+ png_uint_32 valid_chunks;
+# define CHUNK_NONE 0
+# define CHUNK_sBIT PNG_INFO_sBIT
+# define CHUNK_tRNS PNG_INFO_tRNS
+ png_byte color_mask_required;
+ png_byte color_mask_absent;
+# define COLOR_MASK_X 0
+# define COLOR_MASK_P PNG_COLOR_MASK_PALETTE
+# define COLOR_MASK_C PNG_COLOR_MASK_COLOR
+# define COLOR_MASK_A PNG_COLOR_MASK_ALPHA
+# define COLOR_MASK_ALL (PALETTE+COLOR+ALPHA) /* absent = gray, no alpha */
+ png_byte bit_depths;
+# define BD_ALL (1 + 2 + 4 + 8 + 16)
+# define BD_PAL (1 + 2 + 4 + 8)
+# define BD_LOW (1 + 2 + 4)
+# define BD_16 16
+# define BD_TRUE (8+16) /* i.e. true-color depths */
+ png_byte when;
+# define TRANSFORM_R 1
+# define TRANSFORM_W 2
+# define TRANSFORM_RW 3
+ png_byte tested; /* the transform was tested somewhere */
+} transform_info[] =
+{
+ /* List ALL the PNG_TRANSFORM_ macros here. Check for support using the READ
+ * macros; even if the transform is supported on write it cannot be tested
+ * without the read support.
+ */
+# define T(name,chunk,cm_required,cm_absent,bd,when)\
+ { #name, PNG_TRANSFORM_ ## name, CHUNK_ ## chunk,\
+ COLOR_MASK_ ## cm_required, COLOR_MASK_ ## cm_absent, BD_ ## bd,\
+ TRANSFORM_ ## when, 0/*!tested*/ }
+
+#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
+ T(STRIP_16, NONE, X, X, 16, R),
+ /* drops the bottom 8 bits when bit depth is 16 */
+#endif
+#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
+ T(STRIP_ALPHA, NONE, A, X, ALL, R),
+ /* removes the alpha channel if present */
+#endif
+#ifdef PNG_WRITE_PACK_SUPPORTED
+# define TRANSFORM_RW_PACK TRANSFORM_RW
+#else
+# define TRANSFORM_RW_PACK TRANSFORM_R
+#endif
+#ifdef PNG_READ_PACK_SUPPORTED
+ T(PACKING, NONE, X, X, LOW, RW_PACK),
+ /* unpacks low-bit-depth components into 1 byte per component on read,
+ * reverses this on write.
+ */
+#endif
+#ifdef PNG_WRITE_PACKSWAP_SUPPORTED
+# define TRANSFORM_RW_PACKSWAP TRANSFORM_RW
+#else
+# define TRANSFORM_RW_PACKSWAP TRANSFORM_R
+#endif
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
+ T(PACKSWAP, NONE, X, X, LOW, RW_PACKSWAP),
+ /* reverses the order of low-bit-depth components packed into a byte */
+#endif
+#ifdef PNG_READ_EXPAND_SUPPORTED
+ T(EXPAND, NONE, P, X, ALL, R),
+ /* expands PLTE PNG files to RGB (no tRNS) or RGBA (tRNS) *
+ * Note that the 'EXPAND' transform does lots of different things: */
+ T(EXPAND, NONE, X, C, ALL, R),
+ /* expands grayscale PNG files to RGB, or RGBA */
+ T(EXPAND, tRNS, X, A, ALL, R),
+ /* expands the tRNS chunk in files without alpha */
+#endif
+#ifdef PNG_WRITE_INVERT_SUPPORTED
+# define TRANSFORM_RW_INVERT TRANSFORM_RW
+#else
+# define TRANSFORM_RW_INVERT TRANSFORM_R
+#endif
+#ifdef PNG_READ_INVERT_SUPPORTED
+ T(INVERT_MONO, NONE, X, C, ALL, RW_INVERT),
+ /* converts gray-scale components to 1..0 from 0..1 */
+#endif
+#ifdef PNG_WRITE_SHIFT_SUPPORTED
+# define TRANSFORM_RW_SHIFT TRANSFORM_RW
+#else
+# define TRANSFORM_RW_SHIFT TRANSFORM_R
+#endif
+#ifdef PNG_READ_SHIFT_SUPPORTED
+ T(SHIFT, sBIT, X, X, ALL, RW_SHIFT),
+ /* reduces component values to the original range based on the sBIT chunk,
+ * this is only partially reversible - the low bits are lost and cannot be
+ * recovered on write. In fact write code replicates the bits to generate
+ * new low-order bits.
+ */
+#endif
+#ifdef PNG_WRITE_BGR_SUPPORTED
+# define TRANSFORM_RW_BGR TRANSFORM_RW
+#else
+# define TRANSFORM_RW_BGR TRANSFORM_R
+#endif
+#ifdef PNG_READ_BGR_SUPPORTED
+ T(BGR, NONE, C, P, TRUE, RW_BGR),
+ /* reverses the rgb component values of true-color pixels */
+#endif
+#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
+# define TRANSFORM_RW_SWAP_ALPHA TRANSFORM_RW
+#else
+# define TRANSFORM_RW_SWAP_ALPHA TRANSFORM_R
+#endif
+#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
+ T(SWAP_ALPHA, NONE, A, X, TRUE, RW_SWAP_ALPHA),
+ /* swaps the alpha channel of RGBA or GA pixels to the front - ARGB or
+ * AG, on write reverses the process.
+ */
+#endif
+#ifdef PNG_WRITE_SWAP_SUPPORTED
+# define TRANSFORM_RW_SWAP TRANSFORM_RW
+#else
+# define TRANSFORM_RW_SWAP TRANSFORM_R
+#endif
+#ifdef PNG_READ_SWAP_SUPPORTED
+ T(SWAP_ENDIAN, NONE, X, P, 16, RW_SWAP),
+ /* byte-swaps 16-bit component values */
+#endif
+#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
+# define TRANSFORM_RW_INVERT_ALPHA TRANSFORM_RW
+#else
+# define TRANSFORM_RW_INVERT_ALPHA TRANSFORM_R
+#endif
+#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
+ T(INVERT_ALPHA, NONE, A, X, TRUE, RW_INVERT_ALPHA),
+ /* converts an alpha channel from 0..1 to 1..0 */
+#endif
+#ifdef PNG_WRITE_FILLER_SUPPORTED
+ T(STRIP_FILLER_BEFORE, NONE, A, P, TRUE, W), /* 'A' for a filler! */
+ /* on write skips a leading filler channel; testing requires data with a
+ * filler channel so this is produced from RGBA or GA images by removing
+ * the 'alpha' flag from the color type in place.
+ */
+ T(STRIP_FILLER_AFTER, NONE, A, P, TRUE, W),
+ /* on write strips a trailing filler channel */
+#endif
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
+ T(GRAY_TO_RGB, NONE, X, C, ALL, R),
+ /* expands grayscale images to RGB, also causes the palette part of
+ * 'EXPAND' to happen. Low bit depth grayscale images are expanded to
+ * 8-bits per component and no attempt is made to convert the image to a
+ * palette image. While this transform is partially reversible
+ * png_write_png does not currently support this.
+ */
+ T(GRAY_TO_RGB, NONE, P, X, ALL, R),
+ /* The 'palette' side effect mentioned above; a bit bogus but this is the
+ * way the libpng code works.
+ */
+#endif
+#ifdef PNG_READ_EXPAND_16_SUPPORTED
+ T(EXPAND_16, NONE, X, X, PAL, R),
+ /* expands images to 16-bits per component, as a side effect expands
+ * palette images to RGB and expands the tRNS chunk if present, so it can
+ * modify 16-bit per component images as well:
+ */
+ T(EXPAND_16, tRNS, X, A, 16, R),
+ /* side effect of EXPAND_16 - expands the tRNS chunk in an RGB or G 16-bit
+ * image.
+ */
+#endif
+#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
+ T(SCALE_16, NONE, X, X, 16, R),
+ /* scales 16-bit components to 8-bits. */
+#endif
+
+ { NULL /*name*/, 0, 0, 0, 0, 0, 0, 0/*!tested*/ }
+
+#undef T
+};
+
+#define ARRAY_SIZE(a) ((sizeof a)/(sizeof a[0]))
+#define TTABLE_SIZE ARRAY_SIZE(transform_info)
+
+/* Some combinations of options that should be reversible are not; these cases
+ * are bugs.
+ */
+static int known_bad_combos[][2] =
+{
+ /* problem, antidote */
+ { PNG_TRANSFORM_SHIFT | PNG_TRANSFORM_INVERT_ALPHA, 0/*antidote*/ }
+};
+
+static int
+is_combo(int transforms)
+{
+ return transforms & (transforms-1); /* non-zero if more than one set bit */
+}
+
+static int
+first_transform(int transforms)
+{
+ return transforms & -transforms; /* lowest set bit */
+}
+
+static int
+is_bad_combo(int transforms)
+{
+ unsigned int i;
+
+ for (i=0; i<ARRAY_SIZE(known_bad_combos); ++i)
+ {
+ int combo = known_bad_combos[i][0];
+
+ if ((combo & transforms) == combo &&
+ (transforms & known_bad_combos[i][1]) == 0)
+ return 1;
+ }
+
+ return 0; /* combo is ok */
+}
+
+static const char *
+transform_name(int t)
+ /* The name, if 't' has multiple bits set the name of the lowest set bit is
+ * returned.
+ */
+{
+ unsigned int i;
+
+ t &= -t; /* first set bit */
+
+ for (i=0; i<TTABLE_SIZE; ++i) if (transform_info[i].name != NULL)
+ {
+ if ((transform_info[i].transform & t) != 0)
+ return transform_info[i].name;
+ }
+
+ return "invalid transform";
+}
+
+/* Variables calculated by validate_T below and used to record all the supported
+ * transforms. Need (unsigned int) here because of the places where these
+ * values are used (unsigned compares in the 'exhaustive' iterator.)
+ */
+static unsigned int read_transforms, write_transforms, rw_transforms;
+
+static void
+validate_T(void)
+ /* Validate the above table - this just builds the above values */
+{
+ unsigned int i;
+
+ for (i=0; i<TTABLE_SIZE; ++i) if (transform_info[i].name != NULL)
+ {
+ if (transform_info[i].when & TRANSFORM_R)
+ read_transforms |= transform_info[i].transform;
+
+ if (transform_info[i].when & TRANSFORM_W)
+ write_transforms |= transform_info[i].transform;
+ }
+
+ /* Reversible transforms are those which are supported on both read and
+ * write.
+ */
+ rw_transforms = read_transforms & write_transforms;
+}
+
+/* FILE DATA HANDLING
+ * The original file is cached in memory. During write the output file is
+ * written to memory.
+ *
+ * In both cases the file data is held in a linked list of buffers - not all
+ * of these are in use at any time.
+ */
+#define NEW(type) ((type *)malloc(sizeof (type)))
+#define DELETE(ptr) (free(ptr))
+
+struct buffer_list
+{
+ struct buffer_list *next; /* next buffer in list */
+ png_byte buffer[1024]; /* the actual buffer */
+};
+
+struct buffer
+{
+ struct buffer_list *last; /* last buffer in use */
+ size_t end_count; /* bytes in the last buffer */
+ struct buffer_list *current; /* current buffer being read */
+ size_t read_count; /* count of bytes read from current */
+ struct buffer_list first; /* the very first buffer */
+};
+
+static void
+buffer_init(struct buffer *buffer)
+ /* Call this only once for a given buffer */
+{
+ buffer->first.next = NULL;
+ buffer->last = NULL;
+ buffer->current = NULL;
+}
+
+static void
+buffer_destroy_list(struct buffer_list *list)
+{
+ if (list != NULL)
+ {
+ struct buffer_list *next = list->next;
+ DELETE(list);
+ buffer_destroy_list(next);
+ }
+}
+
+static void
+buffer_destroy(struct buffer *buffer)
+{
+ struct buffer_list *list = buffer->first.next;
+ buffer_init(buffer);
+ buffer_destroy_list(list);
+}
+
+#ifdef PNG_WRITE_SUPPORTED
+static void
+buffer_start_write(struct buffer *buffer)
+{
+ buffer->last = &buffer->first;
+ buffer->end_count = 0;
+ buffer->current = NULL;
+}
+#endif
+
+static void
+buffer_start_read(struct buffer *buffer)
+{
+ buffer->current = &buffer->first;
+ buffer->read_count = 0;
+}
+
+#ifdef ENOMEM /* required by POSIX 1003.1 */
+# define MEMORY ENOMEM
+#else
+# define MEMORY ERANGE /* required by ANSI-C */
+#endif
+static struct buffer *
+get_buffer(png_structp pp)
+ /* Used from libpng callbacks to get the current buffer */
+{
+ return (struct buffer*)png_get_io_ptr(pp);
+}
+
+static struct buffer_list *
+buffer_extend(struct buffer_list *current)
+{
+ struct buffer_list *add;
+
+ assert(current->next == NULL);
+
+ add = NEW(struct buffer_list);
+ if (add == NULL)
+ return NULL;
+
+ add->next = NULL;
+ current->next = add;
+
+ return add;
+}
+
+/* Load a buffer from a file; does the equivalent of buffer_start_write. On a
+ * read error returns an errno value, else returns 0.
+ */
+static int
+buffer_from_file(struct buffer *buffer, FILE *fp)
+{
+ struct buffer_list *last = &buffer->first;
+ size_t count = 0;
+
+ for (;;)
+ {
+ size_t r = fread(last->buffer+count, 1/*size*/,
+ (sizeof last->buffer)-count, fp);
+
+ if (r > 0)
+ {
+ count += r;
+
+ if (count >= sizeof last->buffer)
+ {
+ assert(count == sizeof last->buffer);
+ count = 0;
+
+ if (last->next == NULL)
+ {
+ last = buffer_extend(last);
+ if (last == NULL)
+ return MEMORY;
+ }
+
+ else
+ last = last->next;
+ }
+ }
+
+ else /* fread failed - probably end of file */
+ {
+ if (feof(fp))
+ {
+ buffer->last = last;
+ buffer->end_count = count;
+ return 0; /* no error */
+ }
+
+ /* Some kind of funky error; errno should be non-zero */
+ return errno == 0 ? ERANGE : errno;
+ }
+ }
+}
+
+/* This structure is used to control the test of a single file. */
+typedef enum
+{
+ VERBOSE, /* switches on all messages */
+ INFORMATION,
+ WARNINGS, /* switches on warnings */
+ LIBPNG_WARNING,
+ APP_WARNING,
+ ERRORS, /* just errors */
+ APP_FAIL, /* continuable error - no need to longjmp */
+ LIBPNG_ERROR, /* this and higher cause a longjmp */
+ LIBPNG_BUG, /* erroneous behavior in libpng */
+ APP_ERROR, /* such as out-of-memory in a callback */
+ QUIET, /* no normal messages */
+ USER_ERROR, /* such as file-not-found */
+ INTERNAL_ERROR
+} error_level;
+#define LEVEL_MASK 0xf /* where the level is in 'options' */
+
+#define EXHAUSTIVE 0x010 /* Test all combinations of active options */
+#define STRICT 0x020 /* Fail on warnings as well as errors */
+#define LOG 0x040 /* Log pass/fail to stdout */
+#define CONTINUE 0x080 /* Continue on APP_FAIL errors */
+#define SKIP_BUGS 0x100 /* Skip over known bugs */
+#define LOG_SKIPPED 0x200 /* Log skipped bugs */
+#define FIND_BAD_COMBOS 0x400 /* Attempt to deduce bad combos */
+#define LIST_COMBOS 0x800 /* List combos by name */
+
+/* Result masks apply to the result bits in the 'results' field below; these
+ * bits are simple 1U<<error_level. A pass requires either nothing worse than
+ * warnings (--relaxes) or nothing worse than information (--strict)
+ */
+#define RESULT_STRICT(r) (((r) & ~((1U<<WARNINGS)-1)) == 0)
+#define RESULT_RELAXED(r) (((r) & ~((1U<<ERRORS)-1)) == 0)
+
+struct display
+{
+ jmp_buf error_return; /* Where to go to on error */
+
+ const char *filename; /* The name of the original file */
+ const char *operation; /* Operation being performed */
+ int transforms; /* Transform used in operation */
+ png_uint_32 options; /* See display_log below */
+ png_uint_32 results; /* A mask of errors seen */
+
+
+ png_structp original_pp; /* used on the original read */
+ png_infop original_ip; /* set by the original read */
+
+ png_size_t original_rowbytes; /* of the original rows: */
+ png_bytepp original_rows; /* from the original read */
+
+ /* Original chunks valid */
+ png_uint_32 chunks;
+
+ /* Original IHDR information */
+ png_uint_32 width;
+ png_uint_32 height;
+ int bit_depth;
+ int color_type;
+ int interlace_method;
+ int compression_method;
+ int filter_method;
+
+ /* Derived information for the original image. */
+ int active_transforms; /* transforms that do something on read */
+ int ignored_transforms; /* transforms that should do nothing */
+
+ /* Used on a read, both the original read and when validating a written
+ * image.
+ */
+ png_structp read_pp;
+ png_infop read_ip;
+
+# ifdef PNG_WRITE_SUPPORTED
+ /* Used to write a new image (the original info_ptr is used) */
+ png_structp write_pp;
+ struct buffer written_file; /* where the file gets written */
+# endif
+
+ struct buffer original_file; /* Data read from the original file */
+};
+
+static void
+display_init(struct display *dp)
+ /* Call this only once right at the start to initialize the control
+ * structure, the (struct buffer) lists are maintained across calls - the
+ * memory is not freed.
+ */
+{
+ memset(dp, 0, sizeof *dp);
+ dp->options = WARNINGS; /* default to !verbose, !quiet */
+ dp->filename = NULL;
+ dp->operation = NULL;
+ dp->original_pp = NULL;
+ dp->original_ip = NULL;
+ dp->original_rows = NULL;
+ dp->read_pp = NULL;
+ dp->read_ip = NULL;
+ buffer_init(&dp->original_file);
+
+# ifdef PNG_WRITE_SUPPORTED
+ dp->write_pp = NULL;
+ buffer_init(&dp->written_file);
+# endif
+}
+
+static void
+display_clean_read(struct display *dp)
+{
+ if (dp->read_pp != NULL)
+ png_destroy_read_struct(&dp->read_pp, &dp->read_ip, NULL);
+}
+
+#ifdef PNG_WRITE_SUPPORTED
+static void
+display_clean_write(struct display *dp)
+{
+ if (dp->write_pp != NULL)
+ png_destroy_write_struct(&dp->write_pp, NULL);
+}
+#endif
+
+static void
+display_clean(struct display *dp)
+{
+# ifdef PNG_WRITE_SUPPORTED
+ display_clean_write(dp);
+# endif
+ display_clean_read(dp);
+
+ dp->original_rowbytes = 0;
+ dp->original_rows = NULL;
+ dp->chunks = 0;
+
+ png_destroy_read_struct(&dp->original_pp, &dp->original_ip, NULL);
+ /* leave the filename for error detection */
+ dp->results = 0; /* reset for next time */
+}
+
+static void
+display_destroy(struct display *dp)
+{
+ /* Release any memory held in the display. */
+# ifdef PNG_WRITE_SUPPORTED
+ buffer_destroy(&dp->written_file);
+# endif
+
+ buffer_destroy(&dp->original_file);
+}
+
+static struct display *
+get_dp(png_structp pp)
+ /* The display pointer is always stored in the png_struct error pointer */
+{
+ struct display *dp = (struct display*)png_get_error_ptr(pp);
+
+ if (dp == NULL)
+ {
+ fprintf(stderr, "pngimage: internal error (no display)\n");
+ exit(99); /* prevents a crash */
+ }
+
+ return dp;
+}
+
+/* error handling */
+#ifdef __GNUC__
+# define VGATTR __attribute__((__format__ (__printf__,3,4)))
+ /* Required to quiet GNUC warnings when the compiler sees a stdarg function
+ * that calls one of the stdio v APIs.
+ */
+#else
+# define VGATTR
+#endif
+static void VGATTR
+display_log(struct display *dp, error_level level, const char *fmt, ...)
+ /* 'level' is as above, fmt is a stdio style format string. This routine
+ * does not return if level is above LIBPNG_WARNING
+ */
+{
+ dp->results |= 1U << level;
+
+ if (level > (error_level)(dp->options & LEVEL_MASK))
+ {
+ const char *lp;
+ va_list ap;
+
+ switch (level)
+ {
+ case INFORMATION: lp = "information"; break;
+ case LIBPNG_WARNING: lp = "warning(libpng)"; break;
+ case APP_WARNING: lp = "warning(pngimage)"; break;
+ case APP_FAIL: lp = "error(continuable)"; break;
+ case LIBPNG_ERROR: lp = "error(libpng)"; break;
+ case LIBPNG_BUG: lp = "bug(libpng)"; break;
+ case APP_ERROR: lp = "error(pngimage)"; break;
+ case USER_ERROR: lp = "error(user)"; break;
+
+ case INTERNAL_ERROR: /* anything unexpected is an internal error: */
+ case VERBOSE: case WARNINGS: case ERRORS: case QUIET:
+ default: lp = "bug(pngimage)"; break;
+ }
+
+ fprintf(stderr, "%s: %s: %s",
+ dp->filename != NULL ? dp->filename : "<stdin>", lp, dp->operation);
+
+ if (dp->transforms != 0)
+ {
+ int tr = dp->transforms;
+
+ if (is_combo(tr))
+ {
+ if (dp->options & LIST_COMBOS)
+ {
+ int trx = tr;
+
+ fprintf(stderr, "(");
+ if (trx)
+ {
+ int start = 0;
+
+ while (trx)
+ {
+ int trz = trx & -trx;
+
+ if (start) fprintf(stderr, "+");
+ fprintf(stderr, "%s", transform_name(trz));
+ start = 1;
+ trx &= ~trz;
+ }
+ }
+
+ else
+ fprintf(stderr, "-");
+ fprintf(stderr, ")");
+ }
+
+ else
+ fprintf(stderr, "(0x%x)", tr);
+ }
+
+ else
+ fprintf(stderr, "(%s)", transform_name(tr));
+ }
+
+ fprintf(stderr, ": ");
+
+ va_start(ap, fmt);
+ vfprintf(stderr, fmt, ap);
+ va_end(ap);
+
+ fputc('\n', stderr);
+ }
+ /* else do not output any message */
+
+ /* Errors cause this routine to exit to the fail code */
+ if (level > APP_FAIL || (level > ERRORS && !(dp->options & CONTINUE)))
+ longjmp(dp->error_return, level);
+}
+
+/* error handler callbacks for libpng */
+static void PNGCBAPI
+display_warning(png_structp pp, png_const_charp warning)
+{
+ display_log(get_dp(pp), LIBPNG_WARNING, "%s", warning);
+}
+
+static void PNGCBAPI
+display_error(png_structp pp, png_const_charp error)
+{
+ struct display *dp = get_dp(pp);
+
+ display_log(dp, LIBPNG_ERROR, "%s", error);
+}
+
+static void
+display_cache_file(struct display *dp, const char *filename)
+ /* Does the initial cache of the file. */
+{
+ FILE *fp;
+ int ret;
+
+ dp->filename = filename;
+
+ if (filename != NULL)
+ {
+ fp = fopen(filename, "rb");
+ if (fp == NULL)
+ display_log(dp, USER_ERROR, "open failed: %s", strerror(errno));
+ }
+
+ else
+ fp = stdin;
+
+ ret = buffer_from_file(&dp->original_file, fp);
+
+ fclose(fp);
+
+ if (ret != 0)
+ display_log(dp, APP_ERROR, "read failed: %s", strerror(ret));
+}
+
+static void
+buffer_read(struct display *dp, struct buffer *bp, png_bytep data,
+ png_size_t size)
+{
+ struct buffer_list *last = bp->current;
+ size_t read_count = bp->read_count;
+
+ while (size > 0)
+ {
+ size_t avail;
+
+ if (last == NULL ||
+ (last == bp->last && read_count >= bp->end_count))
+ {
+ display_log(dp, USER_ERROR, "file truncated (%lu bytes)",
+ (unsigned long)size);
+ /*NOTREACHED*/
+ break;
+ }
+
+ else if (read_count >= sizeof last->buffer)
+ {
+ /* Move to the next buffer: */
+ last = last->next;
+ read_count = 0;
+ bp->current = last; /* Avoid update outside the loop */
+
+ /* And do a sanity check (the EOF case is caught above) */
+ if (last == NULL)
+ {
+ display_log(dp, INTERNAL_ERROR, "damaged buffer list");
+ /*NOTREACHED*/
+ break;
+ }
+ }
+
+ avail = (sizeof last->buffer) - read_count;
+ if (avail > size)
+ avail = size;
+
+ memcpy(data, last->buffer + read_count, avail);
+ read_count += avail;
+ size -= avail;
+ data += avail;
+ }
+
+ bp->read_count = read_count;
+}
+
+static void PNGCBAPI
+read_function(png_structp pp, png_bytep data, png_size_t size)
+{
+ buffer_read(get_dp(pp), get_buffer(pp), data, size);
+}
+
+static void
+read_png(struct display *dp, struct buffer *bp, const char *operation,
+ int transforms)
+{
+ png_structp pp;
+ png_infop ip;
+
+ /* This cleans out any previous read and sets operation and transforms to
+ * empty.
+ */
+ display_clean_read(dp);
+
+ if (operation != NULL) /* else this is a verify and do not overwrite info */
+ {
+ dp->operation = operation;
+ dp->transforms = transforms;
+ }
+
+ dp->read_pp = pp = png_create_read_struct(PNG_LIBPNG_VER_STRING, dp,
+ display_error, display_warning);
+ if (pp == NULL)
+ display_log(dp, LIBPNG_ERROR, "failed to create read struct");
+
+ /* The png_read_png API requires us to make the info struct, but it does the
+ * call to png_read_info.
+ */
+ dp->read_ip = ip = png_create_info_struct(pp);
+ if (ip == NULL)
+ display_log(dp, LIBPNG_ERROR, "failed to create info struct");
+
+# ifdef PNG_SET_USER_LIMITS_SUPPORTED
+ /* Remove the user limits, if any */
+ png_set_user_limits(pp, 0x7fffffff, 0x7fffffff);
+# endif
+
+ /* Set the IO handling */
+ buffer_start_read(bp);
+ png_set_read_fn(pp, bp, read_function);
+
+ png_read_png(pp, ip, transforms, NULL/*params*/);
+
+#if 0 /* crazy debugging */
+ {
+ png_bytep pr = png_get_rows(pp, ip)[0];
+ size_t rb = png_get_rowbytes(pp, ip);
+ size_t cb;
+ char c = ' ';
+
+ fprintf(stderr, "%.4x %2d (%3lu bytes):", transforms, png_get_bit_depth(pp,ip), (unsigned long)rb);
+
+ for (cb=0; cb<rb; ++cb)
+ fputc(c, stderr), fprintf(stderr, "%.2x", pr[cb]), c='.';
+
+ fputc('\n', stderr);
+ }
+#endif
+}
+
+static void
+update_display(struct display *dp)
+ /* called once after the first read to update all the info, original_pp and
+ * original_ip must have been filled in.
+ */
+{
+ png_structp pp;
+ png_infop ip;
+
+ /* Now perform the initial read with a 0 tranform. */
+ read_png(dp, &dp->original_file, "original read", 0/*no transform*/);
+
+ /* Move the result to the 'original' fields */
+ dp->original_pp = pp = dp->read_pp, dp->read_pp = NULL;
+ dp->original_ip = ip = dp->read_ip, dp->read_ip = NULL;
+
+ dp->original_rowbytes = png_get_rowbytes(pp, ip);
+ if (dp->original_rowbytes == 0)
+ display_log(dp, LIBPNG_BUG, "png_get_rowbytes returned 0");
+
+ dp->chunks = png_get_valid(pp, ip, 0xffffffff);
+ if ((dp->chunks & PNG_INFO_IDAT) == 0) /* set by png_read_png */
+ display_log(dp, LIBPNG_BUG, "png_read_png did not set IDAT flag");
+
+ dp->original_rows = png_get_rows(pp, ip);
+ if (dp->original_rows == NULL)
+ display_log(dp, LIBPNG_BUG, "png_read_png did not create row buffers");
+
+ if (!png_get_IHDR(pp, ip,
+ &dp->width, &dp->height, &dp->bit_depth, &dp->color_type,
+ &dp->interlace_method, &dp->compression_method, &dp->filter_method))
+ display_log(dp, LIBPNG_BUG, "png_get_IHDR failed");
+
+ /* 'active' transforms are discovered based on the original image format;
+ * running one active transform can activate others. At present the code
+ * does not attempt to determine the closure.
+ */
+ {
+ png_uint_32 chunks = dp->chunks;
+ int active = 0, inactive = 0;
+ int ct = dp->color_type;
+ int bd = dp->bit_depth;
+ unsigned int i;
+
+ for (i=0; i<TTABLE_SIZE; ++i) if (transform_info[i].name != NULL)
+ {
+ int transform = transform_info[i].transform;
+
+ if ((transform_info[i].valid_chunks == 0 ||
+ (transform_info[i].valid_chunks & chunks) != 0) &&
+ (transform_info[i].color_mask_required & ct) ==
+ transform_info[i].color_mask_required &&
+ (transform_info[i].color_mask_absent & ct) == 0 &&
+ (transform_info[i].bit_depths & bd) != 0 &&
+ (transform_info[i].when & TRANSFORM_R) != 0)
+ active |= transform;
+
+ else if ((transform_info[i].when & TRANSFORM_R) != 0)
+ inactive |= transform;
+ }
+
+ /* Some transforms appear multiple times in the table; the 'active' status
+ * is the logical OR of these and the inactive status must be adjusted to
+ * take this into account.
+ */
+ inactive &= ~active;
+
+ dp->active_transforms = active;
+ dp->ignored_transforms = inactive; /* excluding write-only transforms */
+ }
+}
+
+static int
+compare_read(struct display *dp, int applied_transforms)
+{
+ /* Compare the png_info from read_ip with original_info */
+ size_t rowbytes;
+ png_uint_32 width, height;
+ int bit_depth, color_type;
+ int interlace_method, compression_method, filter_method;
+ const char *e = NULL;
+
+ png_get_IHDR(dp->read_pp, dp->read_ip, &width, &height, &bit_depth,
+ &color_type, &interlace_method, &compression_method, &filter_method);
+
+# define C(item) if (item != dp->item) \
+ display_log(dp, APP_WARNING, "IHDR " #item "(%lu) changed to %lu",\
+ (unsigned long)dp->item, (unsigned long)item), e = #item
+
+ /* The IHDR should be identical: */
+ C(width);
+ C(height);
+ C(bit_depth);
+ C(color_type);
+ C(interlace_method);
+ C(compression_method);
+ C(filter_method);
+
+ /* 'e' remains set to the name of the last thing changed: */
+ if (e)
+ display_log(dp, APP_ERROR, "IHDR changed (%s)", e);
+
+ /* All the chunks from the original PNG should be preserved in the output PNG
+ * because the PNG format has not been changed.
+ */
+ {
+ unsigned long chunks =
+ png_get_valid(dp->read_pp, dp->read_ip, 0xffffffff);
+
+ if (chunks != dp->chunks)
+ display_log(dp, APP_FAIL, "PNG chunks changed from 0x%lx to 0x%lx",
+ (unsigned long)dp->chunks, chunks);
+ }
+
+ /* rowbytes should be the same */
+ rowbytes = png_get_rowbytes(dp->read_pp, dp->read_ip);
+
+ /* NOTE: on 64-bit systems this may trash the top bits of rowbytes,
+ * which could lead to weird error messages.
+ */
+ if (rowbytes != dp->original_rowbytes)
+ display_log(dp, APP_ERROR, "PNG rowbytes changed from %lu to %lu",
+ (unsigned long)dp->original_rowbytes, (unsigned long)rowbytes);
+
+ /* The rows should be the same too, unless the applied transforms includes
+ * the shift transform, in which case low bits may have been lost.
+ */
+ {
+ png_bytepp rows = png_get_rows(dp->read_pp, dp->read_ip);
+ unsigned int mask; /* mask (if not zero) for the final byte */
+
+ if (bit_depth < 8)
+ {
+ /* Need the stray bits at the end, this depends only on the low bits
+ * of the image width; overflow does not matter. If the width is an
+ * exact multiple of 8 bits this gives a mask of 0, not 0xff.
+ */
+ mask = 0xff & (0xff00 >> ((bit_depth * width) & 7));
+ }
+
+ else
+ mask = 0;
+
+ if (rows == NULL)
+ display_log(dp, LIBPNG_BUG, "png_get_rows returned NULL");
+
+ if ((applied_transforms & PNG_TRANSFORM_SHIFT) == 0 ||
+ (dp->active_transforms & PNG_TRANSFORM_SHIFT) == 0 ||
+ color_type == PNG_COLOR_TYPE_PALETTE)
+ {
+ unsigned long y;
+
+ for (y=0; y<height; ++y)
+ {
+ png_bytep row = rows[y];
+ png_bytep orig = dp->original_rows[y];
+
+ if (memcmp(row, orig, rowbytes-(mask != 0)) != 0 || (mask != 0 &&
+ ((row[rowbytes-1] & mask) != (orig[rowbytes-1] & mask))))
+ {
+ size_t x;
+
+ /* Find the first error */
+ for (x=0; x<rowbytes-1; ++x) if (row[x] != orig[x])
+ break;
+
+ display_log(dp, APP_FAIL,
+ "byte(%lu,%lu) changed 0x%.2x -> 0x%.2x",
+ (unsigned long)x, (unsigned long)y, orig[x], row[x]);
+ return 0; /* don't keep reporting failed rows on 'continue' */
+ }
+ }
+ }
+
+ else
+ {
+ unsigned long y;
+ int bpp; /* bits-per-pixel then bytes-per-pixel */
+ /* components are up to 8 bytes in size */
+ png_byte sig_bits[8];
+ png_color_8p sBIT;
+
+ if (png_get_sBIT(dp->read_pp, dp->read_ip, &sBIT) != PNG_INFO_sBIT)
+ display_log(dp, INTERNAL_ERROR,
+ "active shift transform but no sBIT in file");
+
+ switch (color_type)
+ {
+ case PNG_COLOR_TYPE_GRAY:
+ sig_bits[0] = sBIT->gray;
+ bpp = bit_depth;
+ break;
+
+ case PNG_COLOR_TYPE_GA:
+ sig_bits[0] = sBIT->gray;
+ sig_bits[1] = sBIT->alpha;
+ bpp = 2 * bit_depth;
+ break;
+
+ case PNG_COLOR_TYPE_RGB:
+ sig_bits[0] = sBIT->red;
+ sig_bits[1] = sBIT->green;
+ sig_bits[2] = sBIT->blue;
+ bpp = 3 * bit_depth;
+ break;
+
+ case PNG_COLOR_TYPE_RGBA:
+ sig_bits[0] = sBIT->red;
+ sig_bits[1] = sBIT->green;
+ sig_bits[2] = sBIT->blue;
+ sig_bits[3] = sBIT->alpha;
+ bpp = 4 * bit_depth;
+ break;
+
+ default:
+ display_log(dp, LIBPNG_ERROR, "invalid colour type %d",
+ color_type);
+ /*NOTREACHED*/
+ bpp = 0;
+ break;
+ }
+
+ {
+ int b;
+
+ for (b=0; 8*b<bpp; ++b)
+ {
+ /* libpng should catch this; if not there is a security issue
+ * because an app (like this one) may overflow an array. In fact
+ * libpng doesn't catch this at present.
+ */
+ if (sig_bits[b] == 0 || sig_bits[b] > bit_depth/*!palette*/)
+ display_log(dp, LIBPNG_BUG,
+ "invalid sBIT[%u] value %d returned for PNG bit depth %d",
+ b, sig_bits[b], bit_depth);
+ }
+ }
+
+ if (bpp < 8 && bpp != bit_depth)
+ {
+ /* sanity check; this is a grayscale PNG; something is wrong in the
+ * code above.
+ */
+ display_log(dp, INTERNAL_ERROR, "invalid bpp %u for bit_depth %u",
+ bpp, bit_depth);
+ }
+
+ switch (bit_depth)
+ {
+ int b;
+
+ case 16: /* Two bytes per component, big-endian */
+ for (b = (bpp >> 4); b > 0; --b)
+ {
+ unsigned int sig = (unsigned int)(0xffff0000 >> sig_bits[b]);
+
+ sig_bits[2*b+1] = (png_byte)sig;
+ sig_bits[2*b+0] = (png_byte)(sig >> 8); /* big-endian */
+ }
+ break;
+
+ case 8: /* One byte per component */
+ for (b=0; b*8 < bpp; ++b)
+ sig_bits[b] = (png_byte)(0xff00 >> sig_bits[b]);
+ break;
+
+ case 1: /* allowed, but dumb */
+ /* Value is 1 */
+ sig_bits[0] = 0xff;
+ break;
+
+ case 2: /* Replicate 4 times */
+ /* Value is 1 or 2 */
+ b = 0x3 & ((0x3<<2) >> sig_bits[0]);
+ b |= b << 2;
+ b |= b << 4;
+ sig_bits[0] = (png_byte)b;
+ break;
+
+ case 4: /* Relicate twice */
+ /* Value is 1, 2, 3 or 4 */
+ b = 0xf & ((0xf << 4) >> sig_bits[0]);
+ b |= b << 4;
+ sig_bits[0] = (png_byte)b;
+ break;
+
+ default:
+ display_log(dp, LIBPNG_BUG, "invalid bit depth %d", bit_depth);
+ break;
+ }
+
+ /* Convert bpp to bytes; this gives '1' for low-bit depth grayscale,
+ * where there are multiple pixels per byte.
+ */
+ bpp = (bpp+7) >> 3;
+
+ /* The mask can be combined with sig_bits[0] */
+ if (mask != 0)
+ {
+ mask &= sig_bits[0];
+
+ if (bpp != 1 || mask == 0)
+ display_log(dp, INTERNAL_ERROR, "mask calculation error %u, %u",
+ bpp, mask);
+ }
+
+ for (y=0; y<height; ++y)
+ {
+ png_bytep row = rows[y];
+ png_bytep orig = dp->original_rows[y];
+ unsigned long x;
+
+ for (x=0; x<(width-(mask!=0)); ++x)
+ {
+ int b;
+
+ for (b=0; b<bpp; ++b)
+ {
+ if ((*row++ & sig_bits[b]) != (*orig++ & sig_bits[b]))
+ {
+ display_log(dp, APP_FAIL,
+ "significant bits at (%lu[%u],%lu) changed %.2x->%.2x",
+ x, b, y, orig[-1], row[-1]);
+ return 0;
+ }
+ }
+ }
+
+ if (mask != 0 && (*row & mask) != (*orig & mask))
+ {
+ display_log(dp, APP_FAIL,
+ "significant bits at (%lu[end],%lu) changed", x, y);
+ return 0;
+ }
+ } /* for y */
+ }
+ }
+
+ return 1; /* compare succeeded */
+}
+
+#ifdef PNG_WRITE_SUPPORTED
+static void
+buffer_write(struct display *dp, struct buffer *buffer, png_bytep data,
+ png_size_t size)
+ /* Generic write function used both from the write callback provided to
+ * libpng and from the generic read code.
+ */
+{
+ /* Write the data into the buffer, adding buffers as required */
+ struct buffer_list *last = buffer->last;
+ size_t end_count = buffer->end_count;
+
+ while (size > 0)
+ {
+ size_t avail;
+
+ if (end_count >= sizeof last->buffer)
+ {
+ if (last->next == NULL)
+ {
+ last = buffer_extend(last);
+
+ if (last == NULL)
+ display_log(dp, APP_ERROR, "out of memory saving file");
+ }
+
+ else
+ last = last->next;
+
+ buffer->last = last; /* avoid the need to rewrite every time */
+ end_count = 0;
+ }
+
+ avail = (sizeof last->buffer) - end_count;
+ if (avail > size)
+ avail = size;
+
+ memcpy(last->buffer + end_count, data, avail);
+ end_count += avail;
+ size -= avail;
+ data += avail;
+ }
+
+ buffer->end_count = end_count;
+}
+
+static void PNGCBAPI
+write_function(png_structp pp, png_bytep data, png_size_t size)
+{
+ buffer_write(get_dp(pp), get_buffer(pp), data, size);
+}
+
+static void
+write_png(struct display *dp, png_infop ip, int transforms)
+{
+ display_clean_write(dp); /* safety */
+
+ buffer_start_write(&dp->written_file);
+ dp->operation = "write";
+ dp->transforms = transforms;
+
+ dp->write_pp = png_create_write_struct(PNG_LIBPNG_VER_STRING, dp,
+ display_error, display_warning);
+
+ if (dp->write_pp == NULL)
+ display_log(dp, APP_ERROR, "failed to create write png_struct");
+
+ png_set_write_fn(dp->write_pp, &dp->written_file, write_function,
+ NULL/*flush*/);
+
+# ifdef PNG_SET_USER_LIMITS_SUPPORTED
+ /* Remove the user limits, if any */
+ png_set_user_limits(dp->write_pp, 0x7fffffff, 0x7fffffff);
+# endif
+
+ /* Certain transforms require the png_info to be zapped to allow the
+ * transform to work correctly.
+ */
+ if (transforms & (PNG_TRANSFORM_PACKING|
+ PNG_TRANSFORM_STRIP_FILLER|
+ PNG_TRANSFORM_STRIP_FILLER_BEFORE))
+ {
+ int ct = dp->color_type;
+
+ if (transforms & (PNG_TRANSFORM_STRIP_FILLER|
+ PNG_TRANSFORM_STRIP_FILLER_BEFORE))
+ ct &= ~PNG_COLOR_MASK_ALPHA;
+
+ png_set_IHDR(dp->write_pp, ip, dp->width, dp->height, dp->bit_depth, ct,
+ dp->interlace_method, dp->compression_method, dp->filter_method);
+ }
+
+ png_write_png(dp->write_pp, ip, transforms, NULL/*params*/);
+
+ /* Clean it on the way out - if control returns to the caller then the
+ * written_file contains the required data.
+ */
+ display_clean_write(dp);
+}
+#endif /* WRITE_SUPPORTED */
+
+static int
+skip_transform(struct display *dp, int tr)
+ /* Helper to test for a bad combo and log it if it is skipped */
+{
+ if ((dp->options & SKIP_BUGS) != 0 && is_bad_combo(tr))
+ {
+ /* Log this to stdout if logging is on, otherwise just do an information
+ * display_log.
+ */
+ if ((dp->options & LOG_SKIPPED) != 0)
+ {
+ printf("SKIP: %s transforms ", dp->filename);
+
+ while (tr != 0)
+ {
+ int next = first_transform(tr);
+ tr &= ~next;
+
+ printf("%s", transform_name(next));
+ if (tr != 0)
+ putchar('+');
+ }
+
+ putchar('\n');
+ }
+
+ else
+ display_log(dp, INFORMATION, "%s: skipped known bad combo 0x%x",
+ dp->filename, tr);
+
+ return 1; /* skip */
+ }
+
+ return 0; /* don't skip */
+}
+
+static void
+test_one_file(struct display *dp, const char *filename)
+{
+ /* First cache the file and update the display original file
+ * information for the new file.
+ */
+ dp->operation = "cache file";
+ dp->transforms = 0;
+ display_cache_file(dp, filename);
+ update_display(dp);
+
+ /* First test: if there are options that should be ignored for this file
+ * verify that they really are ignored.
+ */
+ if (dp->ignored_transforms != 0)
+ {
+ read_png(dp, &dp->original_file, "ignored transforms",
+ dp->ignored_transforms);
+
+ /* The result should be identical to the original_rows */
+ if (!compare_read(dp, 0/*transforms applied*/))
+ return; /* no point testing more */
+ }
+
+#ifdef PNG_WRITE_SUPPORTED
+ /* Second test: write the original PNG data out to a new file (to test the
+ * write side) then read the result back in and make sure that it hasn't
+ * changed.
+ */
+ dp->operation = "write";
+ write_png(dp, dp->original_ip, 0/*transforms*/);
+ read_png(dp, &dp->written_file, NULL, 0/*transforms*/);
+ if (!compare_read(dp, 0/*transforms applied*/))
+ return;
+#endif
+
+ /* Third test: the active options. Test each in turn, or, with the
+ * EXHAUSTIVE option, test all possible combinations.
+ */
+ {
+ /* Use unsigned int here because the code below to increment through all
+ * the possibilities exhaustively has to use a compare and that must be
+ * unsigned, because some transforms are negative on a 16-bit system.
+ */
+ unsigned int active = dp->active_transforms;
+ const int exhaustive = (dp->options & EXHAUSTIVE) != 0;
+ unsigned int current = first_transform(active);
+ unsigned int bad_transforms = 0;
+ unsigned int bad_combo = ~0U; /* bitwise AND of failing transforms */
+ unsigned int bad_combo_list = 0; /* bitwise OR of failures */
+
+ for (;;)
+ {
+ read_png(dp, &dp->original_file, "active transforms", current);
+
+ /* If this involved any irreversible transformations then if we write
+ * it out with just the reversible transformations and read it in again
+ * with the same transforms we should get the same thing. At present
+ * this isn't done - it just seems like a waste of time and it would
+ * require two sets of read png_struct/png_info.
+ *
+ * If there were no irreversible transformations then if we write it
+ * out and read it back in again (without the reversible transforms)
+ * we should get back to the place where we started.
+ */
+#ifdef PNG_WRITE_SUPPORTED
+ if ((current & write_transforms) == current)
+ {
+ /* All transforms reversible: write the PNG with the transformations
+ * reversed, then read it back in with no transformations. The
+ * result should be the same as the original apart from the loss of
+ * low order bits because of the SHIFT/sBIT transform.
+ */
+ dp->operation = "reversible transforms";
+ write_png(dp, dp->read_ip, current);
+
+ /* And if this is read back in, because all the transformations were
+ * reversible, the result should be the same.
+ */
+ read_png(dp, &dp->written_file, NULL, 0);
+ if (!compare_read(dp, current/*for the SHIFT/sBIT transform*/))
+ {
+ /* This set of transforms failed. If a single bit is set - if
+ * there is just one transform - don't include this in further
+ * 'exhaustive' tests. Notice that each transform is tested on
+ * its own before testing combos in the exhaustive case.
+ */
+ if (is_combo(current))
+ {
+ bad_combo &= current;
+ bad_combo_list |= current;
+ }
+
+ else
+ bad_transforms |= current;
+ }
+ }
+#endif
+
+ /* Now move to the next transform */
+ if (exhaustive) /* all combinations */
+ {
+ unsigned int next = current;
+
+ do
+ {
+ if (next == read_transforms) /* Everything tested */
+ goto combo;
+
+ ++next;
+ } /* skip known bad combos if the relevant option is set; skip
+ * combos involving known bad single transforms in all cases.
+ */
+ while ( (next & read_transforms) <= current
+ || (next & active) == 0 /* skip cases that do nothing */
+ || (next & bad_transforms) != 0
+ || skip_transform(dp, next));
+
+ assert((next & read_transforms) == next);
+ current = next;
+ }
+
+ else /* one at a time */
+ {
+ active &= ~current;
+
+ if (active == 0)
+ goto combo;
+
+ current = first_transform(active);
+ }
+ }
+
+combo:
+ if (dp->options & FIND_BAD_COMBOS)
+ {
+ /* bad_combos identifies the combos that occur in all failing cases;
+ * bad_combo_list identifies transforms that do not prevent the
+ * failure.
+ */
+ if (bad_combo != ~0U)
+ printf("%s[0x%x]: PROBLEM: 0x%x[0x%x] ANTIDOTE: 0x%x\n",
+ dp->filename, active, bad_combo, bad_combo_list,
+ rw_transforms & ~bad_combo_list);
+
+ else
+ printf("%s: no %sbad combos found\n", dp->filename,
+ (dp->options & SKIP_BUGS) ? "additional " : "");
+ }
+ }
+}
+
+static int
+do_test(struct display *dp, const char *file)
+ /* Exists solely to isolate the setjmp clobbers */
+{
+ int ret = setjmp(dp->error_return);
+
+ if (ret == 0)
+ {
+ test_one_file(dp, file);
+ return 0;
+ }
+
+ else if (ret < ERRORS) /* shouldn't longjmp on warnings */
+ display_log(dp, INTERNAL_ERROR, "unexpected return code %d", ret);
+
+ return ret;
+}
+
+int
+main(const int argc, const char * const * const argv)
+{
+ /* For each file on the command line test it with a range of transforms */
+ int option_end, ilog = 0;
+ struct display d;
+
+ validate_T();
+ display_init(&d);
+
+ for (option_end=1; option_end<argc; ++option_end)
+ {
+ const char *name = argv[option_end];
+
+ if (strcmp(name, "--verbose") == 0)
+ d.options = (d.options & ~LEVEL_MASK) | VERBOSE;
+
+ else if (strcmp(name, "--warnings") == 0)
+ d.options = (d.options & ~LEVEL_MASK) | WARNINGS;
+
+ else if (strcmp(name, "--errors") == 0)
+ d.options = (d.options & ~LEVEL_MASK) | ERRORS;
+
+ else if (strcmp(name, "--quiet") == 0)
+ d.options = (d.options & ~LEVEL_MASK) | QUIET;
+
+ else if (strcmp(name, "--exhaustive") == 0)
+ d.options |= EXHAUSTIVE;
+
+ else if (strcmp(name, "--fast") == 0)
+ d.options &= ~EXHAUSTIVE;
+
+ else if (strcmp(name, "--strict") == 0)
+ d.options |= STRICT;
+
+ else if (strcmp(name, "--relaxed") == 0)
+ d.options &= ~STRICT;
+
+ else if (strcmp(name, "--log") == 0)
+ {
+ ilog = option_end; /* prevent display */
+ d.options |= LOG;
+ }
+
+ else if (strcmp(name, "--nolog") == 0)
+ d.options &= ~LOG;
+
+ else if (strcmp(name, "--continue") == 0)
+ d.options |= CONTINUE;
+
+ else if (strcmp(name, "--stop") == 0)
+ d.options &= ~CONTINUE;
+
+ else if (strcmp(name, "--skip-bugs") == 0)
+ d.options |= SKIP_BUGS;
+
+ else if (strcmp(name, "--test-all") == 0)
+ d.options &= ~SKIP_BUGS;
+
+ else if (strcmp(name, "--log-skipped") == 0)
+ d.options |= LOG_SKIPPED;
+
+ else if (strcmp(name, "--nolog-skipped") == 0)
+ d.options &= ~LOG_SKIPPED;
+
+ else if (strcmp(name, "--find-bad-combos") == 0)
+ d.options |= FIND_BAD_COMBOS;
+
+ else if (strcmp(name, "--nofind-bad-combos") == 0)
+ d.options &= ~FIND_BAD_COMBOS;
+
+ else if (strcmp(name, "--list-combos") == 0)
+ d.options |= LIST_COMBOS;
+
+ else if (strcmp(name, "--nolist-combos") == 0)
+ d.options &= ~LIST_COMBOS;
+
+ else if (name[0] == '-' && name[1] == '-')
+ {
+ fprintf(stderr, "pngimage: %s: unknown option\n", name);
+ return 99;
+ }
+
+ else
+ break; /* Not an option */
+ }
+
+ {
+ int i;
+ int errors = 0;
+
+ for (i=option_end; i<argc; ++i)
+ {
+ {
+ int ret = do_test(&d, argv[i]);
+
+ if (ret > QUIET) /* abort on user or internal error */
+ return 99;
+ }
+
+ /* Here on any return, including failures, except user/internal issues
+ */
+ {
+ const int pass = (d.options & STRICT) ?
+ RESULT_STRICT(d.results) : RESULT_RELAXED(d.results);
+
+ if (!pass)
+ ++errors;
+
+ if (d.options & LOG)
+ {
+ int j;
+
+ printf("%s: pngimage ", pass ? "PASS" : "FAIL");
+
+ for (j=1; j<option_end; ++j) if (j != ilog)
+ printf("%s ", argv[j]);
+
+ printf("%s\n", d.filename);
+ }
+ }
+
+ display_clean(&d);
+ }
+
+ /* Release allocated memory */
+ display_destroy(&d);
+
+ return errors != 0;
+ }
+}
+#else /* !INFO_IMAGE || !SEQUENTIAL_READ || !READ_PNG*/
+int
+main(void)
+{
+ fprintf(stderr, "pngimage: no support for png_read/write_image\n");
+ return 77;
+}
+#endif
diff --git a/libpng/contrib/libtests/pngstest-errors.h b/libpng/contrib/libtests/pngstest-errors.h
new file mode 100644
index 0000000..3356f1c
--- /dev/null
+++ b/libpng/contrib/libtests/pngstest-errors.h
@@ -0,0 +1,165 @@
+/* contrib/libtests/pngstest-errors.h
+ *
+ * BUILT USING: libpng version 1.6.19beta03 - September 25, 2015
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * THIS IS A MACHINE GENERATED FILE: do not edit it directly!
+ * Instead run:
+ *
+ * pngstest --accumulate
+ *
+ * on as many PNG files as possible; at least PNGSuite and
+ * contrib/libtests/testpngs.
+ */
+static png_uint_16 gpc_error[16/*in*/][16/*out*/][4/*a*/] =
+{
+ { /* input: sRGB-gray */
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 372, 0 }, { 0, 0, 372, 0 }, { 0, 0, 372, 0 }, { 0, 0, 372, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: sRGB-gray+alpha */
+ { 0, 19, 0, 0 }, { 0, 0, 0, 0 }, { 0, 20, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 897, 788, 0 }, { 0, 897, 788, 0 }, { 0, 897, 788, 0 }, { 0, 897, 788, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: sRGB-rgb */
+ { 0, 0, 19, 0 }, { 0, 0, 19, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 893, 0 }, { 0, 0, 893, 0 }, { 0, 0, 811, 0 }, { 0, 0, 811, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: sRGB-rgb+alpha */
+ { 0, 16, 17, 0 }, { 0, 17, 17, 0 }, { 0, 19, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 850, 875, 0 }, { 0, 850, 875, 0 }, { 0, 897, 788, 0 }, { 0, 897, 788, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: linear-gray */
+ { 0, 0, 9, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: linear-gray+alpha */
+ { 0, 74, 9, 0 }, { 0, 20, 9, 0 }, { 0, 74, 9, 0 }, { 0, 20, 9, 0 },
+ { 0, 0, 0, 0 }, { 0, 1, 0, 0 }, { 0, 0, 0, 0 }, { 0, 1, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: linear-rgb */
+ { 0, 0, 9, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 },
+ { 0, 0, 4, 0 }, { 0, 0, 4, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: linear-rgb+alpha */
+ { 0, 126, 143, 0 }, { 0, 11, 7, 0 }, { 0, 74, 9, 0 }, { 0, 17, 9, 0 },
+ { 0, 4, 4, 0 }, { 0, 5, 4, 0 }, { 0, 0, 0, 0 }, { 0, 1, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-sRGB-gray */
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-sRGB-gray+alpha */
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-sRGB-rgb */
+ { 0, 0, 13, 0 }, { 0, 0, 13, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 },
+ { 0, 0, 673, 0 }, { 0, 0, 673, 0 }, { 0, 0, 674, 0 }, { 0, 0, 674, 0 },
+ { 0, 0, 1, 0 }, { 0, 0, 1, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 460, 0 }, { 0, 0, 460, 0 }, { 0, 0, 263, 0 }, { 0, 0, 263, 0 }
+ }, { /* input: color-mapped-sRGB-rgb+alpha */
+ { 0, 6, 8, 0 }, { 0, 7, 8, 0 }, { 0, 75, 9, 0 }, { 0, 9, 9, 0 },
+ { 0, 585, 427, 0 }, { 0, 585, 427, 0 }, { 0, 717, 514, 0 }, { 0, 717, 514, 0 },
+ { 0, 1, 1, 0 }, { 0, 1, 1, 0 }, { 0, 1, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 13323, 460, 0 }, { 0, 427, 460, 0 }, { 0, 16480, 263, 0 }, { 0, 243, 263, 0 }
+ }, { /* input: color-mapped-linear-gray */
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 282, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-linear-gray+alpha */
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 253, 282, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-linear-rgb */
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 265, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-linear-rgb+alpha */
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 },
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 243, 265, 0 }
+ }
+};
+static png_uint_16 gpc_error_via_linear[16][4/*out*/][4] =
+{
+ { /* input: sRGB-gray */
+ { 0, 0, 7, 0 }, { 0, 0, 7, 0 }, { 0, 0, 7, 0 }, { 0, 0, 7, 0 }
+ }, { /* input: sRGB-gray+alpha */
+ { 0, 15, 15, 0 }, { 0, 186, 15, 0 }, { 0, 15, 15, 0 }, { 0, 186, 15, 0 }
+ }, { /* input: sRGB-rgb */
+ { 0, 0, 20, 0 }, { 0, 0, 20, 0 }, { 0, 0, 15, 0 }, { 0, 0, 15, 0 }
+ }, { /* input: sRGB-rgb+alpha */
+ { 0, 16, 17, 0 }, { 0, 187, 17, 0 }, { 0, 15, 15, 0 }, { 0, 186, 15, 0 }
+ }, { /* input: linear-gray */
+ { 0, 0, 1, 0 }, { 0, 0, 1, 0 }, { 0, 0, 1, 0 }, { 0, 0, 1, 0 }
+ }, { /* input: linear-gray+alpha */
+ { 0, 1, 1, 0 }, { 0, 1, 1, 0 }, { 0, 1, 1, 0 }, { 0, 1, 1, 0 }
+ }, { /* input: linear-rgb */
+ { 0, 0, 1, 0 }, { 0, 0, 1, 0 }, { 0, 0, 1, 0 }, { 0, 0, 1, 0 }
+ }, { /* input: linear-rgb+alpha */
+ { 0, 1, 1, 0 }, { 0, 9, 1, 0 }, { 0, 1, 1, 0 }, { 0, 1, 1, 0 }
+ }, { /* input: color-mapped-sRGB-gray */
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-sRGB-gray+alpha */
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-sRGB-rgb */
+ { 0, 0, 13, 0 }, { 0, 0, 13, 0 }, { 0, 0, 14, 0 }, { 0, 0, 14, 0 }
+ }, { /* input: color-mapped-sRGB-rgb+alpha */
+ { 0, 4, 8, 0 }, { 0, 9, 8, 0 }, { 0, 9, 5, 0 }, { 0, 32, 5, 0 }
+ }, { /* input: color-mapped-linear-gray */
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-linear-gray+alpha */
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-linear-rgb */
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }, { /* input: color-mapped-linear-rgb+alpha */
+ { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }, { 0, 0, 0, 0 }
+ }
+};
+static png_uint_16 gpc_error_to_colormap[8/*i*/][8/*o*/][4] =
+{
+ { /* input: sRGB-gray */
+ { 0, 0, 9, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 }, { 0, 0, 9, 0 },
+ { 0, 0, 560, 0 }, { 0, 0, 560, 0 }, { 0, 0, 560, 0 }, { 0, 0, 560, 0 }
+ }, { /* input: sRGB-gray+alpha */
+ { 0, 19, 9, 0 }, { 0, 255, 9, 25 }, { 0, 88, 9, 0 }, { 0, 255, 9, 25 },
+ { 0, 1012, 928, 0 }, { 0, 16026, 928, 6425 }, { 0, 1012, 928, 0 }, { 0, 16026, 928, 6425 }
+ }, { /* input: sRGB-rgb */
+ { 0, 0, 19, 0 }, { 0, 0, 19, 0 }, { 0, 0, 25, 0 }, { 0, 0, 25, 0 },
+ { 0, 0, 962, 0 }, { 0, 0, 962, 0 }, { 0, 0, 13677, 0 }, { 0, 0, 13677, 0 }
+ }, { /* input: sRGB-rgb+alpha */
+ { 0, 63, 77, 0 }, { 0, 255, 19, 25 }, { 0, 225, 25, 0 }, { 0, 255, 25, 67 },
+ { 0, 17534, 18491, 0 }, { 0, 15736, 2824, 6425 }, { 0, 14019, 13677, 0 }, { 0, 50115, 13677, 17219 }
+ }, { /* input: linear-gray */
+ { 0, 0, 73, 0 }, { 0, 0, 73, 0 }, { 0, 0, 73, 0 }, { 0, 0, 73, 0 },
+ { 0, 0, 18817, 0 }, { 0, 0, 18817, 0 }, { 0, 0, 18817, 0 }, { 0, 0, 18817, 0 }
+ }, { /* input: linear-gray+alpha */
+ { 0, 74, 74, 0 }, { 0, 255, 74, 25 }, { 0, 99, 74, 0 }, { 0, 255, 74, 25 },
+ { 0, 18919, 18907, 0 }, { 0, 24549, 18907, 6553 }, { 0, 18919, 18907, 0 }, { 0, 24549, 18907, 6553 }
+ }, { /* input: linear-rgb */
+ { 0, 0, 73, 0 }, { 0, 0, 73, 0 }, { 0, 0, 98, 0 }, { 0, 0, 98, 0 },
+ { 0, 0, 18664, 0 }, { 0, 0, 18664, 0 }, { 0, 0, 24998, 0 }, { 0, 0, 24998, 0 }
+ }, { /* input: linear-rgb+alpha */
+ { 0, 181, 196, 0 }, { 0, 255, 61, 25 }, { 206, 187, 98, 0 }, { 0, 255, 98, 67 },
+ { 0, 18141, 18137, 0 }, { 0, 17494, 17504, 6553 }, { 0, 24979, 24992, 0 }, { 0, 49172, 24992, 17347 }
+ }
+};
+/* END MACHINE GENERATED */
diff --git a/libpng/contrib/libtests/pngstest.c b/libpng/contrib/libtests/pngstest.c
new file mode 100644
index 0000000..3374c72
--- /dev/null
+++ b/libpng/contrib/libtests/pngstest.c
@@ -0,0 +1,3722 @@
+/*-
+ * pngstest.c
+ *
+ * Copyright (c) 2013-2015 John Cunningham Bowler
+ *
+ * Last changed in libpng 1.6.19 [(PENDING RELEASE)]
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * Test for the PNG 'simplified' APIs.
+ */
+#define _ISOC90_SOURCE 1
+#define MALLOC_CHECK_ 2/*glibc facility: turn on debugging*/
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <errno.h>
+#include <ctype.h>
+#include <math.h>
+
+#if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H)
+# include <config.h>
+#endif
+
+/* Define the following to use this test against your installed libpng, rather
+ * than the one being built here:
+ */
+#ifdef PNG_FREESTANDING_TESTS
+# include <png.h>
+#else
+# include "../../png.h"
+#endif
+
+#ifdef PNG_SIMPLIFIED_READ_SUPPORTED /* Else nothing can be done */
+#include "../tools/sRGB.h"
+
+/* KNOWN ISSUES
+ *
+ * These defines switch on alternate algorithms for format conversions to match
+ * the current libpng implementation; they are set to allow pngstest to pass
+ * even though libpng is producing answers that are not as correct as they
+ * should be.
+ */
+#define ALLOW_UNUSED_GPC 0
+ /* If true include unused static GPC functions and declare an external array
+ * of them to hide the fact that they are unused. This is for development
+ * use while testing the correct function to use to take into account libpng
+ * misbehavior, such as using a simple power law to correct sRGB to linear.
+ */
+
+/* The following is to support direct compilation of this file as C++ */
+#ifdef __cplusplus
+# define voidcast(type, value) static_cast<type>(value)
+# define aligncastconst(type, value) \
+ static_cast<type>(static_cast<const void*>(value))
+#else
+# define voidcast(type, value) (value)
+# define aligncastconst(type, value) ((const void*)(value))
+#endif /* __cplusplus */
+
+/* During parallel runs of pngstest each temporary file needs a unique name,
+ * this is used to permit uniqueness using a command line argument which can be
+ * up to 22 characters long.
+ */
+static char tmpf[23] = "TMP";
+
+/* Generate random bytes. This uses a boring repeatable algorithm and it
+ * is implemented here so that it gives the same set of numbers on every
+ * architecture. It's a linear congruential generator (Knuth or Sedgewick
+ * "Algorithms") but it comes from the 'feedback taps' table in Horowitz and
+ * Hill, "The Art of Electronics".
+ */
+static void
+make_random_bytes(png_uint_32* seed, void* pv, size_t size)
+{
+ png_uint_32 u0 = seed[0], u1 = seed[1];
+ png_bytep bytes = voidcast(png_bytep, pv);
+
+ /* There are thirty three bits, the next bit in the sequence is bit-33 XOR
+ * bit-20. The top 1 bit is in u1, the bottom 32 are in u0.
+ */
+ size_t i;
+ for (i=0; i<size; ++i)
+ {
+ /* First generate 8 new bits then shift them in at the end. */
+ png_uint_32 u = ((u0 >> (20-8)) ^ ((u1 << 7) | (u0 >> (32-7)))) & 0xff;
+ u1 <<= 8;
+ u1 |= u0 >> 24;
+ u0 <<= 8;
+ u0 |= u;
+ *bytes++ = (png_byte)u;
+ }
+
+ seed[0] = u0;
+ seed[1] = u1;
+}
+
+static void
+random_color(png_colorp color)
+{
+ static png_uint_32 color_seed[2] = { 0x12345678, 0x9abcdef };
+ make_random_bytes(color_seed, color, sizeof *color);
+}
+
+/* Math support - neither Cygwin nor Visual Studio have C99 support and we need
+ * a predictable rounding function, so make one here:
+ */
+static double
+closestinteger(double x)
+{
+ return floor(x + .5);
+}
+
+/* Cast support: remove GCC whines. */
+static png_byte
+u8d(double d)
+{
+ d = closestinteger(d);
+ return (png_byte)d;
+}
+
+static png_uint_16
+u16d(double d)
+{
+ d = closestinteger(d);
+ return (png_uint_16)d;
+}
+
+/* sRGB support: use exact calculations rounded to the nearest int, see the
+ * fesetround() call in main(). sRGB_to_d optimizes the 8 to 16-bit conversion.
+ */
+static double sRGB_to_d[256];
+static double g22_to_d[256];
+
+static void
+init_sRGB_to_d(void)
+{
+ int i;
+
+ sRGB_to_d[0] = 0;
+ for (i=1; i<255; ++i)
+ sRGB_to_d[i] = linear_from_sRGB(i/255.);
+ sRGB_to_d[255] = 1;
+
+ g22_to_d[0] = 0;
+ for (i=1; i<255; ++i)
+ g22_to_d[i] = pow(i/255., 1/.45455);
+ g22_to_d[255] = 1;
+}
+
+static png_byte
+sRGB(double linear /*range 0.0 .. 1.0*/)
+{
+ return u8d(255 * sRGB_from_linear(linear));
+}
+
+static png_byte
+isRGB(int fixed_linear)
+{
+ return sRGB(fixed_linear / 65535.);
+}
+
+#if 0 /* not used */
+static png_byte
+unpremultiply(int component, int alpha)
+{
+ if (alpha <= component)
+ return 255; /* Arbitrary, but consistent with the libpng code */
+
+ else if (alpha >= 65535)
+ return isRGB(component);
+
+ else
+ return sRGB((double)component / alpha);
+}
+#endif
+
+static png_uint_16
+ilinear(int fixed_srgb)
+{
+ return u16d(65535 * sRGB_to_d[fixed_srgb]);
+}
+
+static png_uint_16
+ilineara(int fixed_srgb, int alpha)
+{
+ return u16d((257 * alpha) * sRGB_to_d[fixed_srgb]);
+}
+
+static png_uint_16
+ilinear_g22(int fixed_srgb)
+{
+ return u16d(65535 * g22_to_d[fixed_srgb]);
+}
+
+#if ALLOW_UNUSED_GPC
+static png_uint_16
+ilineara_g22(int fixed_srgb, int alpha)
+{
+ return u16d((257 * alpha) * g22_to_d[fixed_srgb]);
+}
+#endif
+
+static double
+YfromRGBint(int ir, int ig, int ib)
+{
+ double r = ir;
+ double g = ig;
+ double b = ib;
+ return YfromRGB(r, g, b);
+}
+
+#if 0 /* unused */
+/* The error that results from using a 2.2 power law in place of the correct
+ * sRGB transform, given an 8-bit value which might be either sRGB or power-law.
+ */
+static int
+power_law_error8(int value)
+{
+ if (value > 0 && value < 255)
+ {
+ double vd = value / 255.;
+ double e = fabs(
+ pow(sRGB_to_d[value], 1/2.2) - sRGB_from_linear(pow(vd, 2.2)));
+
+ /* Always allow an extra 1 here for rounding errors */
+ e = 1+floor(255 * e);
+ return (int)e;
+ }
+
+ return 0;
+}
+
+static int error_in_sRGB_roundtrip = 56; /* by experiment */
+static int
+power_law_error16(int value)
+{
+ if (value > 0 && value < 65535)
+ {
+ /* Round trip the value through an 8-bit representation but using
+ * non-matching to/from conversions.
+ */
+ double vd = value / 65535.;
+ double e = fabs(
+ pow(sRGB_from_linear(vd), 2.2) - linear_from_sRGB(pow(vd, 1/2.2)));
+
+ /* Always allow an extra 1 here for rounding errors */
+ e = error_in_sRGB_roundtrip+floor(65535 * e);
+ return (int)e;
+ }
+
+ return 0;
+}
+
+static int
+compare_8bit(int v1, int v2, int error_limit, int multiple_algorithms)
+{
+ int e = abs(v1-v2);
+ int ev1, ev2;
+
+ if (e <= error_limit)
+ return 1;
+
+ if (!multiple_algorithms)
+ return 0;
+
+ ev1 = power_law_error8(v1);
+ if (e <= ev1)
+ return 1;
+
+ ev2 = power_law_error8(v2);
+ if (e <= ev2)
+ return 1;
+
+ return 0;
+}
+
+static int
+compare_16bit(int v1, int v2, int error_limit, int multiple_algorithms)
+{
+ int e = abs(v1-v2);
+ int ev1, ev2;
+
+ if (e <= error_limit)
+ return 1;
+
+ /* "multiple_algorithms" in this case means that a color-map has been
+ * involved somewhere, so we can deduce that the values were forced to 8-bit
+ * (like the via_linear case for 8-bit.)
+ */
+ if (!multiple_algorithms)
+ return 0;
+
+ ev1 = power_law_error16(v1);
+ if (e <= ev1)
+ return 1;
+
+ ev2 = power_law_error16(v2);
+ if (e <= ev2)
+ return 1;
+
+ return 0;
+}
+#endif /* unused */
+
+#define READ_FILE 1 /* else memory */
+#define USE_STDIO 2 /* else use file name */
+#define STRICT 4 /* fail on warnings too */
+#define VERBOSE 8
+#define KEEP_TMPFILES 16 /* else delete temporary files */
+#define KEEP_GOING 32
+#define ACCUMULATE 64
+#define FAST_WRITE 128
+#define sRGB_16BIT 256
+
+static void
+print_opts(png_uint_32 opts)
+{
+ if (opts & READ_FILE)
+ printf(" --file");
+ if (opts & USE_STDIO)
+ printf(" --stdio");
+ if (opts & STRICT)
+ printf(" --strict");
+ if (opts & VERBOSE)
+ printf(" --verbose");
+ if (opts & KEEP_TMPFILES)
+ printf(" --preserve");
+ if (opts & KEEP_GOING)
+ printf(" --keep-going");
+ if (opts & ACCUMULATE)
+ printf(" --accumulate");
+ if (!(opts & FAST_WRITE)) /* --fast is currently the default */
+ printf(" --slow");
+ if (opts & sRGB_16BIT)
+ printf(" --sRGB-16bit");
+}
+
+#define FORMAT_NO_CHANGE 0x80000000 /* additional flag */
+
+/* A name table for all the formats - defines the format of the '+' arguments to
+ * pngstest.
+ */
+#define FORMAT_COUNT 64
+#define FORMAT_MASK 0x3f
+static PNG_CONST char * PNG_CONST format_names[FORMAT_COUNT] =
+{
+ "sRGB-gray",
+ "sRGB-gray+alpha",
+ "sRGB-rgb",
+ "sRGB-rgb+alpha",
+ "linear-gray",
+ "linear-gray+alpha",
+ "linear-rgb",
+ "linear-rgb+alpha",
+
+ "color-mapped-sRGB-gray",
+ "color-mapped-sRGB-gray+alpha",
+ "color-mapped-sRGB-rgb",
+ "color-mapped-sRGB-rgb+alpha",
+ "color-mapped-linear-gray",
+ "color-mapped-linear-gray+alpha",
+ "color-mapped-linear-rgb",
+ "color-mapped-linear-rgb+alpha",
+
+ "sRGB-gray",
+ "sRGB-gray+alpha",
+ "sRGB-bgr",
+ "sRGB-bgr+alpha",
+ "linear-gray",
+ "linear-gray+alpha",
+ "linear-bgr",
+ "linear-bgr+alpha",
+
+ "color-mapped-sRGB-gray",
+ "color-mapped-sRGB-gray+alpha",
+ "color-mapped-sRGB-bgr",
+ "color-mapped-sRGB-bgr+alpha",
+ "color-mapped-linear-gray",
+ "color-mapped-linear-gray+alpha",
+ "color-mapped-linear-bgr",
+ "color-mapped-linear-bgr+alpha",
+
+ "sRGB-gray",
+ "alpha+sRGB-gray",
+ "sRGB-rgb",
+ "alpha+sRGB-rgb",
+ "linear-gray",
+ "alpha+linear-gray",
+ "linear-rgb",
+ "alpha+linear-rgb",
+
+ "color-mapped-sRGB-gray",
+ "color-mapped-alpha+sRGB-gray",
+ "color-mapped-sRGB-rgb",
+ "color-mapped-alpha+sRGB-rgb",
+ "color-mapped-linear-gray",
+ "color-mapped-alpha+linear-gray",
+ "color-mapped-linear-rgb",
+ "color-mapped-alpha+linear-rgb",
+
+ "sRGB-gray",
+ "alpha+sRGB-gray",
+ "sRGB-bgr",
+ "alpha+sRGB-bgr",
+ "linear-gray",
+ "alpha+linear-gray",
+ "linear-bgr",
+ "alpha+linear-bgr",
+
+ "color-mapped-sRGB-gray",
+ "color-mapped-alpha+sRGB-gray",
+ "color-mapped-sRGB-bgr",
+ "color-mapped-alpha+sRGB-bgr",
+ "color-mapped-linear-gray",
+ "color-mapped-alpha+linear-gray",
+ "color-mapped-linear-bgr",
+ "color-mapped-alpha+linear-bgr",
+};
+
+/* Decode an argument to a format number. */
+static png_uint_32
+formatof(const char *arg)
+{
+ char *ep;
+ unsigned long format = strtoul(arg, &ep, 0);
+
+ if (ep > arg && *ep == 0 && format < FORMAT_COUNT)
+ return (png_uint_32)format;
+
+ else for (format=0; format < FORMAT_COUNT; ++format)
+ {
+ if (strcmp(format_names[format], arg) == 0)
+ return (png_uint_32)format;
+ }
+
+ fprintf(stderr, "pngstest: format name '%s' invalid\n", arg);
+ return FORMAT_COUNT;
+}
+
+/* Bitset/test functions for formats */
+#define FORMAT_SET_COUNT (FORMAT_COUNT / 32)
+typedef struct
+{
+ png_uint_32 bits[FORMAT_SET_COUNT];
+}
+format_list;
+
+static void format_init(format_list *pf)
+{
+ int i;
+ for (i=0; i<FORMAT_SET_COUNT; ++i)
+ pf->bits[i] = 0; /* All off */
+}
+
+#if 0 /* currently unused */
+static void format_clear(format_list *pf)
+{
+ int i;
+ for (i=0; i<FORMAT_SET_COUNT; ++i)
+ pf->bits[i] = 0;
+}
+#endif
+
+static int format_is_initial(format_list *pf)
+{
+ int i;
+ for (i=0; i<FORMAT_SET_COUNT; ++i)
+ if (pf->bits[i] != 0)
+ return 0;
+
+ return 1;
+}
+
+static int format_set(format_list *pf, png_uint_32 format)
+{
+ if (format < FORMAT_COUNT)
+ return pf->bits[format >> 5] |= ((png_uint_32)1) << (format & 31);
+
+ return 0;
+}
+
+#if 0 /* currently unused */
+static int format_unset(format_list *pf, png_uint_32 format)
+{
+ if (format < FORMAT_COUNT)
+ return pf->bits[format >> 5] &= ~((png_uint_32)1) << (format & 31);
+
+ return 0;
+}
+#endif
+
+static int format_isset(format_list *pf, png_uint_32 format)
+{
+ return format < FORMAT_COUNT &&
+ (pf->bits[format >> 5] & (((png_uint_32)1) << (format & 31))) != 0;
+}
+
+static void format_default(format_list *pf, int redundant)
+{
+ if (redundant)
+ {
+ int i;
+
+ /* set everything, including flags that are pointless */
+ for (i=0; i<FORMAT_SET_COUNT; ++i)
+ pf->bits[i] = ~(png_uint_32)0;
+ }
+
+ else
+ {
+ png_uint_32 f;
+
+ for (f=0; f<FORMAT_COUNT; ++f)
+ {
+ /* Eliminate redundant and unsupported settings. */
+# ifdef PNG_FORMAT_BGR_SUPPORTED
+ /* BGR is meaningless if no color: */
+ if ((f & PNG_FORMAT_FLAG_COLOR) == 0 &&
+ (f & PNG_FORMAT_FLAG_BGR) != 0)
+# else
+ if ((f & 0x10U/*HACK: fixed value*/) != 0)
+# endif
+ continue;
+
+ /* AFIRST is meaningless if no alpha: */
+# ifdef PNG_FORMAT_AFIRST_SUPPORTED
+ if ((f & PNG_FORMAT_FLAG_ALPHA) == 0 &&
+ (f & PNG_FORMAT_FLAG_AFIRST) != 0)
+# else
+ if ((f & 0x20U/*HACK: fixed value*/) != 0)
+# endif
+ continue;
+
+ format_set(pf, f);
+ }
+ }
+}
+
+/* THE Image STRUCTURE */
+/* The super-class of a png_image, contains the decoded image plus the input
+ * data necessary to re-read the file with a different format.
+ */
+typedef struct
+{
+ png_image image;
+ png_uint_32 opts;
+ const char *file_name;
+ int stride_extra;
+ FILE *input_file;
+ png_voidp input_memory;
+ png_size_t input_memory_size;
+ png_bytep buffer;
+ ptrdiff_t stride;
+ png_size_t bufsize;
+ png_size_t allocsize;
+ char tmpfile_name[32];
+ png_uint_16 colormap[256*4];
+}
+Image;
+
+/* Initializer: also sets the permitted error limit for 16-bit operations. */
+static void
+newimage(Image *image)
+{
+ memset(image, 0, sizeof *image);
+}
+
+/* Reset the image to be read again - only needs to rewind the FILE* at present.
+ */
+static void
+resetimage(Image *image)
+{
+ if (image->input_file != NULL)
+ rewind(image->input_file);
+}
+
+/* Free the image buffer; the buffer is re-used on a re-read, this is just for
+ * cleanup.
+ */
+static void
+freebuffer(Image *image)
+{
+ if (image->buffer) free(image->buffer);
+ image->buffer = NULL;
+ image->bufsize = 0;
+ image->allocsize = 0;
+}
+
+/* Delete function; cleans out all the allocated data and the temporary file in
+ * the image.
+ */
+static void
+freeimage(Image *image)
+{
+ freebuffer(image);
+ png_image_free(&image->image);
+
+ if (image->input_file != NULL)
+ {
+ fclose(image->input_file);
+ image->input_file = NULL;
+ }
+
+ if (image->input_memory != NULL)
+ {
+ free(image->input_memory);
+ image->input_memory = NULL;
+ image->input_memory_size = 0;
+ }
+
+ if (image->tmpfile_name[0] != 0 && (image->opts & KEEP_TMPFILES) == 0)
+ {
+ (void)remove(image->tmpfile_name);
+ image->tmpfile_name[0] = 0;
+ }
+}
+
+/* This is actually a re-initializer; allows an image structure to be re-used by
+ * freeing everything that relates to an old image.
+ */
+static void initimage(Image *image, png_uint_32 opts, const char *file_name,
+ int stride_extra)
+{
+ freeimage(image);
+ memset(&image->image, 0, sizeof image->image);
+ image->opts = opts;
+ image->file_name = file_name;
+ image->stride_extra = stride_extra;
+}
+
+/* Make sure the image buffer is big enough; allows re-use of the buffer if the
+ * image is re-read.
+ */
+#define BUFFER_INIT8 73
+static void
+allocbuffer(Image *image)
+{
+ png_size_t size = PNG_IMAGE_BUFFER_SIZE(image->image, image->stride);
+
+ if (size+32 > image->bufsize)
+ {
+ freebuffer(image);
+ image->buffer = voidcast(png_bytep, malloc(size+32));
+ if (image->buffer == NULL)
+ {
+ fflush(stdout);
+ fprintf(stderr,
+ "simpletest: out of memory allocating %lu(+32) byte buffer\n",
+ (unsigned long)size);
+ exit(1);
+ }
+ image->bufsize = size+32;
+ }
+
+ memset(image->buffer, 95, image->bufsize);
+ memset(image->buffer+16, BUFFER_INIT8, size);
+ image->allocsize = size;
+}
+
+/* Make sure 16 bytes match the given byte. */
+static int
+check16(png_const_bytep bp, int b)
+{
+ int i = 16;
+
+ do
+ if (*bp != b) return 1;
+ while (--i);
+
+ return 0;
+}
+
+/* Check for overwrite in the image buffer. */
+static void
+checkbuffer(Image *image, const char *arg)
+{
+ if (check16(image->buffer, 95))
+ {
+ fflush(stdout);
+ fprintf(stderr, "%s: overwrite at start of image buffer\n", arg);
+ exit(1);
+ }
+
+ if (check16(image->buffer+16+image->allocsize, 95))
+ {
+ fflush(stdout);
+ fprintf(stderr, "%s: overwrite at end of image buffer\n", arg);
+ exit(1);
+ }
+}
+
+/* ERROR HANDLING */
+/* Log a terminal error, also frees the libpng part of the image if necessary.
+ */
+static int
+logerror(Image *image, const char *a1, const char *a2, const char *a3)
+{
+ fflush(stdout);
+ if (image->image.warning_or_error)
+ fprintf(stderr, "%s%s%s: %s\n", a1, a2, a3, image->image.message);
+
+ else
+ fprintf(stderr, "%s%s%s\n", a1, a2, a3);
+
+ if (image->image.opaque != NULL)
+ {
+ fprintf(stderr, "%s: image opaque pointer non-NULL on error\n",
+ image->file_name);
+ png_image_free(&image->image);
+ }
+
+ return 0;
+}
+
+/* Log an error and close a file (just a utility to do both things in one
+ * function call.)
+ */
+static int
+logclose(Image *image, FILE *f, const char *name, const char *operation)
+{
+ int e = errno;
+
+ fclose(f);
+ return logerror(image, name, operation, strerror(e));
+}
+
+/* Make sure the png_image has been freed - validates that libpng is doing what
+ * the spec says and freeing the image.
+ */
+static int
+checkopaque(Image *image)
+{
+ if (image->image.opaque != NULL)
+ {
+ png_image_free(&image->image);
+ return logerror(image, image->file_name, ": opaque not NULL", "");
+ }
+
+ else if (image->image.warning_or_error != 0 && (image->opts & STRICT) != 0)
+ return logerror(image, image->file_name, " --strict", "");
+
+ else
+ return 1;
+}
+
+/* IMAGE COMPARISON/CHECKING */
+/* Compare the pixels of two images, which should be the same but aren't. The
+ * images must have been checked for a size match.
+ */
+typedef struct
+{
+ /* The components, for grayscale images the gray value is in 'g' and if alpha
+ * is not present 'a' is set to 255 or 65535 according to format.
+ */
+ int r, g, b, a;
+} Pixel;
+
+typedef struct
+{
+ /* The background as the original sRGB 8-bit value converted to the final
+ * integer format and as a double precision linear value in the range 0..1
+ * for with partially transparent pixels.
+ */
+ int ir, ig, ib;
+ double dr, dg, db; /* linear r,g,b scaled to 0..1 */
+} Background;
+
+/* Basic image formats; control the data but not the layout thereof. */
+#define BASE_FORMATS\
+ (PNG_FORMAT_FLAG_ALPHA|PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_LINEAR)
+
+/* Read a Pixel from a buffer. The code below stores the correct routine for
+ * the format in a function pointer, these are the routines:
+ */
+static void
+gp_g8(Pixel *p, png_const_voidp pb)
+{
+ png_const_bytep pp = voidcast(png_const_bytep, pb);
+
+ p->r = p->g = p->b = pp[0];
+ p->a = 255;
+}
+
+static void
+gp_ga8(Pixel *p, png_const_voidp pb)
+{
+ png_const_bytep pp = voidcast(png_const_bytep, pb);
+
+ p->r = p->g = p->b = pp[0];
+ p->a = pp[1];
+}
+
+#ifdef PNG_FORMAT_AFIRST_SUPPORTED
+static void
+gp_ag8(Pixel *p, png_const_voidp pb)
+{
+ png_const_bytep pp = voidcast(png_const_bytep, pb);
+
+ p->r = p->g = p->b = pp[1];
+ p->a = pp[0];
+}
+#endif
+
+static void
+gp_rgb8(Pixel *p, png_const_voidp pb)
+{
+ png_const_bytep pp = voidcast(png_const_bytep, pb);
+
+ p->r = pp[0];
+ p->g = pp[1];
+ p->b = pp[2];
+ p->a = 255;
+}
+
+#ifdef PNG_FORMAT_BGR_SUPPORTED
+static void
+gp_bgr8(Pixel *p, png_const_voidp pb)
+{
+ png_const_bytep pp = voidcast(png_const_bytep, pb);
+
+ p->r = pp[2];
+ p->g = pp[1];
+ p->b = pp[0];
+ p->a = 255;
+}
+#endif
+
+static void
+gp_rgba8(Pixel *p, png_const_voidp pb)
+{
+ png_const_bytep pp = voidcast(png_const_bytep, pb);
+
+ p->r = pp[0];
+ p->g = pp[1];
+ p->b = pp[2];
+ p->a = pp[3];
+}
+
+#ifdef PNG_FORMAT_BGR_SUPPORTED
+static void
+gp_bgra8(Pixel *p, png_const_voidp pb)
+{
+ png_const_bytep pp = voidcast(png_const_bytep, pb);
+
+ p->r = pp[2];
+ p->g = pp[1];
+ p->b = pp[0];
+ p->a = pp[3];
+}
+#endif
+
+#ifdef PNG_FORMAT_AFIRST_SUPPORTED
+static void
+gp_argb8(Pixel *p, png_const_voidp pb)
+{
+ png_const_bytep pp = voidcast(png_const_bytep, pb);
+
+ p->r = pp[1];
+ p->g = pp[2];
+ p->b = pp[3];
+ p->a = pp[0];
+}
+#endif
+
+#if defined(PNG_FORMAT_AFIRST_SUPPORTED) && defined(PNG_FORMAT_BGR_SUPPORTED)
+static void
+gp_abgr8(Pixel *p, png_const_voidp pb)
+{
+ png_const_bytep pp = voidcast(png_const_bytep, pb);
+
+ p->r = pp[3];
+ p->g = pp[2];
+ p->b = pp[1];
+ p->a = pp[0];
+}
+#endif
+
+static void
+gp_g16(Pixel *p, png_const_voidp pb)
+{
+ png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
+
+ p->r = p->g = p->b = pp[0];
+ p->a = 65535;
+}
+
+static void
+gp_ga16(Pixel *p, png_const_voidp pb)
+{
+ png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
+
+ p->r = p->g = p->b = pp[0];
+ p->a = pp[1];
+}
+
+#ifdef PNG_FORMAT_AFIRST_SUPPORTED
+static void
+gp_ag16(Pixel *p, png_const_voidp pb)
+{
+ png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
+
+ p->r = p->g = p->b = pp[1];
+ p->a = pp[0];
+}
+#endif
+
+static void
+gp_rgb16(Pixel *p, png_const_voidp pb)
+{
+ png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
+
+ p->r = pp[0];
+ p->g = pp[1];
+ p->b = pp[2];
+ p->a = 65535;
+}
+
+#ifdef PNG_FORMAT_BGR_SUPPORTED
+static void
+gp_bgr16(Pixel *p, png_const_voidp pb)
+{
+ png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
+
+ p->r = pp[2];
+ p->g = pp[1];
+ p->b = pp[0];
+ p->a = 65535;
+}
+#endif
+
+static void
+gp_rgba16(Pixel *p, png_const_voidp pb)
+{
+ png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
+
+ p->r = pp[0];
+ p->g = pp[1];
+ p->b = pp[2];
+ p->a = pp[3];
+}
+
+#ifdef PNG_FORMAT_BGR_SUPPORTED
+static void
+gp_bgra16(Pixel *p, png_const_voidp pb)
+{
+ png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
+
+ p->r = pp[2];
+ p->g = pp[1];
+ p->b = pp[0];
+ p->a = pp[3];
+}
+#endif
+
+#ifdef PNG_FORMAT_AFIRST_SUPPORTED
+static void
+gp_argb16(Pixel *p, png_const_voidp pb)
+{
+ png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
+
+ p->r = pp[1];
+ p->g = pp[2];
+ p->b = pp[3];
+ p->a = pp[0];
+}
+#endif
+
+#if defined(PNG_FORMAT_AFIRST_SUPPORTED) && defined(PNG_FORMAT_BGR_SUPPORTED)
+static void
+gp_abgr16(Pixel *p, png_const_voidp pb)
+{
+ png_const_uint_16p pp = voidcast(png_const_uint_16p, pb);
+
+ p->r = pp[3];
+ p->g = pp[2];
+ p->b = pp[1];
+ p->a = pp[0];
+}
+#endif
+
+/* Given a format, return the correct one of the above functions. */
+static void (*
+get_pixel(png_uint_32 format))(Pixel *p, png_const_voidp pb)
+{
+ /* The color-map flag is irrelevant here - the caller of the function
+ * returned must either pass the buffer or, for a color-mapped image, the
+ * correct entry in the color-map.
+ */
+ if (format & PNG_FORMAT_FLAG_LINEAR)
+ {
+ if (format & PNG_FORMAT_FLAG_COLOR)
+ {
+# ifdef PNG_FORMAT_BGR_SUPPORTED
+ if (format & PNG_FORMAT_FLAG_BGR)
+ {
+ if (format & PNG_FORMAT_FLAG_ALPHA)
+ {
+# ifdef PNG_FORMAT_AFIRST_SUPPORTED
+ if (format & PNG_FORMAT_FLAG_AFIRST)
+ return gp_abgr16;
+
+ else
+# endif
+ return gp_bgra16;
+ }
+
+ else
+ return gp_bgr16;
+ }
+
+ else
+# endif
+ {
+ if (format & PNG_FORMAT_FLAG_ALPHA)
+ {
+# ifdef PNG_FORMAT_AFIRST_SUPPORTED
+ if (format & PNG_FORMAT_FLAG_AFIRST)
+ return gp_argb16;
+
+ else
+# endif
+ return gp_rgba16;
+ }
+
+ else
+ return gp_rgb16;
+ }
+ }
+
+ else
+ {
+ if (format & PNG_FORMAT_FLAG_ALPHA)
+ {
+# ifdef PNG_FORMAT_AFIRST_SUPPORTED
+ if (format & PNG_FORMAT_FLAG_AFIRST)
+ return gp_ag16;
+
+ else
+# endif
+ return gp_ga16;
+ }
+
+ else
+ return gp_g16;
+ }
+ }
+
+ else
+ {
+ if (format & PNG_FORMAT_FLAG_COLOR)
+ {
+# ifdef PNG_FORMAT_BGR_SUPPORTED
+ if (format & PNG_FORMAT_FLAG_BGR)
+ {
+ if (format & PNG_FORMAT_FLAG_ALPHA)
+ {
+# ifdef PNG_FORMAT_AFIRST_SUPPORTED
+ if (format & PNG_FORMAT_FLAG_AFIRST)
+ return gp_abgr8;
+
+ else
+# endif
+ return gp_bgra8;
+ }
+
+ else
+ return gp_bgr8;
+ }
+
+ else
+# endif
+ {
+ if (format & PNG_FORMAT_FLAG_ALPHA)
+ {
+# ifdef PNG_FORMAT_AFIRST_SUPPORTED
+ if (format & PNG_FORMAT_FLAG_AFIRST)
+ return gp_argb8;
+
+ else
+# endif
+ return gp_rgba8;
+ }
+
+ else
+ return gp_rgb8;
+ }
+ }
+
+ else
+ {
+ if (format & PNG_FORMAT_FLAG_ALPHA)
+ {
+# ifdef PNG_FORMAT_AFIRST_SUPPORTED
+ if (format & PNG_FORMAT_FLAG_AFIRST)
+ return gp_ag8;
+
+ else
+# endif
+ return gp_ga8;
+ }
+
+ else
+ return gp_g8;
+ }
+ }
+}
+
+/* Convertion between pixel formats. The code above effectively eliminates the
+ * component ordering changes leaving three basic changes:
+ *
+ * 1) Remove an alpha channel by pre-multiplication or compositing on a
+ * background color. (Adding an alpha channel is a no-op.)
+ *
+ * 2) Remove color by mapping to grayscale. (Grayscale to color is a no-op.)
+ *
+ * 3) Convert between 8-bit and 16-bit components. (Both directtions are
+ * relevant.)
+ *
+ * This gives the following base format conversion matrix:
+ *
+ * OUT: ----- 8-bit ----- ----- 16-bit -----
+ * IN G GA RGB RGBA G GA RGB RGBA
+ * 8 G . . . . lin lin lin lin
+ * 8 GA bckg . bckc . pre' pre pre' pre
+ * 8 RGB g8 g8 . . glin glin lin lin
+ * 8 RGBA g8b g8 bckc . gpr' gpre pre' pre
+ * 16 G sRGB sRGB sRGB sRGB . . . .
+ * 16 GA b16g unpg b16c unpc A . A .
+ * 16 RGB sG sG sRGB sRGB g16 g16 . .
+ * 16 RGBA gb16 sGp cb16 sCp g16 g16' A .
+ *
+ * 8-bit to 8-bit:
+ * bckg: composite on gray background
+ * bckc: composite on color background
+ * g8: convert sRGB components to sRGB grayscale
+ * g8b: convert sRGB components to grayscale and composite on gray background
+ *
+ * 8-bit to 16-bit:
+ * lin: make sRGB components linear, alpha := 65535
+ * pre: make sRGB components linear and premultiply by alpha (scale alpha)
+ * pre': as 'pre' but alpha := 65535
+ * glin: make sRGB components linear, convert to grayscale, alpha := 65535
+ * gpre: make sRGB components grayscale and linear and premultiply by alpha
+ * gpr': as 'gpre' but alpha := 65535
+ *
+ * 16-bit to 8-bit:
+ * sRGB: convert linear components to sRGB, alpha := 255
+ * unpg: unpremultiply gray component and convert to sRGB (scale alpha)
+ * unpc: unpremultiply color components and convert to sRGB (scale alpha)
+ * b16g: composite linear onto gray background and convert the result to sRGB
+ * b16c: composite linear onto color background and convert the result to sRGB
+ * sG: convert linear RGB to sRGB grayscale
+ * sGp: unpremultiply RGB then convert to sRGB grayscale
+ * sCp: unpremultiply RGB then convert to sRGB
+ * gb16: composite linear onto background and convert to sRGB grayscale
+ * (order doesn't matter, the composite and grayscale operations permute)
+ * cb16: composite linear onto background and convert to sRGB
+ *
+ * 16-bit to 16-bit:
+ * A: set alpha to 65535
+ * g16: convert linear RGB to linear grayscale (alpha := 65535)
+ * g16': as 'g16' but alpha is unchanged
+ */
+/* Simple copy: */
+static void
+gpc_noop(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+ out->r = in->r;
+ out->g = in->g;
+ out->b = in->b;
+ out->a = in->a;
+}
+
+#if ALLOW_UNUSED_GPC
+static void
+gpc_nop8(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+ if (in->a == 0)
+ out->r = out->g = out->b = 255;
+
+ else
+ {
+ out->r = in->r;
+ out->g = in->g;
+ out->b = in->b;
+ }
+
+ out->a = in->a;
+}
+#endif
+
+#if ALLOW_UNUSED_GPC
+static void
+gpc_nop6(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+ if (in->a == 0)
+ out->r = out->g = out->b = 65535;
+
+ else
+ {
+ out->r = in->r;
+ out->g = in->g;
+ out->b = in->b;
+ }
+
+ out->a = in->a;
+}
+#endif
+
+/* 8-bit to 8-bit conversions */
+/* bckg: composite on gray background */
+static void
+gpc_bckg(Pixel *out, const Pixel *in, const Background *back)
+{
+ if (in->a <= 0)
+ out->r = out->g = out->b = back->ig;
+
+ else if (in->a >= 255)
+ out->r = out->g = out->b = in->g;
+
+ else
+ {
+ double a = in->a / 255.;
+
+ out->r = out->g = out->b = sRGB(sRGB_to_d[in->g] * a + back->dg * (1-a));
+ }
+
+ out->a = 255;
+}
+
+/* bckc: composite on color background */
+static void
+gpc_bckc(Pixel *out, const Pixel *in, const Background *back)
+{
+ if (in->a <= 0)
+ {
+ out->r = back->ir;
+ out->g = back->ig;
+ out->b = back->ib;
+ }
+
+ else if (in->a >= 255)
+ {
+ out->r = in->r;
+ out->g = in->g;
+ out->b = in->b;
+ }
+
+ else
+ {
+ double a = in->a / 255.;
+
+ out->r = sRGB(sRGB_to_d[in->r] * a + back->dr * (1-a));
+ out->g = sRGB(sRGB_to_d[in->g] * a + back->dg * (1-a));
+ out->b = sRGB(sRGB_to_d[in->b] * a + back->db * (1-a));
+ }
+
+ out->a = 255;
+}
+
+/* g8: convert sRGB components to sRGB grayscale */
+static void
+gpc_g8(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+
+ if (in->r == in->g && in->g == in->b)
+ out->r = out->g = out->b = in->g;
+
+ else
+ out->r = out->g = out->b =
+ sRGB(YfromRGB(sRGB_to_d[in->r], sRGB_to_d[in->g], sRGB_to_d[in->b]));
+
+ out->a = in->a;
+}
+
+/* g8b: convert sRGB components to grayscale and composite on gray background */
+static void
+gpc_g8b(Pixel *out, const Pixel *in, const Background *back)
+{
+ if (in->a <= 0)
+ out->r = out->g = out->b = back->ig;
+
+ else if (in->a >= 255)
+ {
+ if (in->r == in->g && in->g == in->b)
+ out->r = out->g = out->b = in->g;
+
+ else
+ out->r = out->g = out->b = sRGB(YfromRGB(
+ sRGB_to_d[in->r], sRGB_to_d[in->g], sRGB_to_d[in->b]));
+ }
+
+ else
+ {
+ double a = in->a/255.;
+
+ out->r = out->g = out->b = sRGB(a * YfromRGB(sRGB_to_d[in->r],
+ sRGB_to_d[in->g], sRGB_to_d[in->b]) + back->dg * (1-a));
+ }
+
+ out->a = 255;
+}
+
+/* 8-bit to 16-bit conversions */
+/* lin: make sRGB components linear, alpha := 65535 */
+static void
+gpc_lin(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+
+ out->r = ilinear(in->r);
+
+ if (in->g == in->r)
+ {
+ out->g = out->r;
+
+ if (in->b == in->r)
+ out->b = out->r;
+
+ else
+ out->b = ilinear(in->b);
+ }
+
+ else
+ {
+ out->g = ilinear(in->g);
+
+ if (in->b == in->r)
+ out->b = out->r;
+
+ else if (in->b == in->g)
+ out->b = out->g;
+
+ else
+ out->b = ilinear(in->b);
+ }
+
+ out->a = 65535;
+}
+
+/* pre: make sRGB components linear and premultiply by alpha (scale alpha) */
+static void
+gpc_pre(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+
+ out->r = ilineara(in->r, in->a);
+
+ if (in->g == in->r)
+ {
+ out->g = out->r;
+
+ if (in->b == in->r)
+ out->b = out->r;
+
+ else
+ out->b = ilineara(in->b, in->a);
+ }
+
+ else
+ {
+ out->g = ilineara(in->g, in->a);
+
+ if (in->b == in->r)
+ out->b = out->r;
+
+ else if (in->b == in->g)
+ out->b = out->g;
+
+ else
+ out->b = ilineara(in->b, in->a);
+ }
+
+ out->a = in->a * 257;
+}
+
+/* pre': as 'pre' but alpha := 65535 */
+static void
+gpc_preq(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+
+ out->r = ilineara(in->r, in->a);
+
+ if (in->g == in->r)
+ {
+ out->g = out->r;
+
+ if (in->b == in->r)
+ out->b = out->r;
+
+ else
+ out->b = ilineara(in->b, in->a);
+ }
+
+ else
+ {
+ out->g = ilineara(in->g, in->a);
+
+ if (in->b == in->r)
+ out->b = out->r;
+
+ else if (in->b == in->g)
+ out->b = out->g;
+
+ else
+ out->b = ilineara(in->b, in->a);
+ }
+
+ out->a = 65535;
+}
+
+/* glin: make sRGB components linear, convert to grayscale, alpha := 65535 */
+static void
+gpc_glin(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+
+ if (in->r == in->g && in->g == in->b)
+ out->r = out->g = out->b = ilinear(in->g);
+
+ else
+ out->r = out->g = out->b = u16d(65535 *
+ YfromRGB(sRGB_to_d[in->r], sRGB_to_d[in->g], sRGB_to_d[in->b]));
+
+ out->a = 65535;
+}
+
+/* gpre: make sRGB components grayscale and linear and premultiply by alpha */
+static void
+gpc_gpre(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+
+ if (in->r == in->g && in->g == in->b)
+ out->r = out->g = out->b = ilineara(in->g, in->a);
+
+ else
+ out->r = out->g = out->b = u16d(in->a * 257 *
+ YfromRGB(sRGB_to_d[in->r], sRGB_to_d[in->g], sRGB_to_d[in->b]));
+
+ out->a = 257 * in->a;
+}
+
+/* gpr': as 'gpre' but alpha := 65535 */
+static void
+gpc_gprq(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+
+ if (in->r == in->g && in->g == in->b)
+ out->r = out->g = out->b = ilineara(in->g, in->a);
+
+ else
+ out->r = out->g = out->b = u16d(in->a * 257 *
+ YfromRGB(sRGB_to_d[in->r], sRGB_to_d[in->g], sRGB_to_d[in->b]));
+
+ out->a = 65535;
+}
+
+/* 8-bit to 16-bit conversions for gAMA 45455 encoded values */
+/* Lin: make gAMA 45455 components linear, alpha := 65535 */
+static void
+gpc_Lin(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+
+ out->r = ilinear_g22(in->r);
+
+ if (in->g == in->r)
+ {
+ out->g = out->r;
+
+ if (in->b == in->r)
+ out->b = out->r;
+
+ else
+ out->b = ilinear_g22(in->b);
+ }
+
+ else
+ {
+ out->g = ilinear_g22(in->g);
+
+ if (in->b == in->r)
+ out->b = out->r;
+
+ else if (in->b == in->g)
+ out->b = out->g;
+
+ else
+ out->b = ilinear_g22(in->b);
+ }
+
+ out->a = 65535;
+}
+
+#if ALLOW_UNUSED_GPC
+/* Pre: make gAMA 45455 components linear and premultiply by alpha (scale alpha)
+ */
+static void
+gpc_Pre(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+
+ out->r = ilineara_g22(in->r, in->a);
+
+ if (in->g == in->r)
+ {
+ out->g = out->r;
+
+ if (in->b == in->r)
+ out->b = out->r;
+
+ else
+ out->b = ilineara_g22(in->b, in->a);
+ }
+
+ else
+ {
+ out->g = ilineara_g22(in->g, in->a);
+
+ if (in->b == in->r)
+ out->b = out->r;
+
+ else if (in->b == in->g)
+ out->b = out->g;
+
+ else
+ out->b = ilineara_g22(in->b, in->a);
+ }
+
+ out->a = in->a * 257;
+}
+#endif
+
+#if ALLOW_UNUSED_GPC
+/* Pre': as 'Pre' but alpha := 65535 */
+static void
+gpc_Preq(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+
+ out->r = ilineara_g22(in->r, in->a);
+
+ if (in->g == in->r)
+ {
+ out->g = out->r;
+
+ if (in->b == in->r)
+ out->b = out->r;
+
+ else
+ out->b = ilineara_g22(in->b, in->a);
+ }
+
+ else
+ {
+ out->g = ilineara_g22(in->g, in->a);
+
+ if (in->b == in->r)
+ out->b = out->r;
+
+ else if (in->b == in->g)
+ out->b = out->g;
+
+ else
+ out->b = ilineara_g22(in->b, in->a);
+ }
+
+ out->a = 65535;
+}
+#endif
+
+#if ALLOW_UNUSED_GPC
+/* Glin: make gAMA 45455 components linear, convert to grayscale, alpha := 65535
+ */
+static void
+gpc_Glin(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+
+ if (in->r == in->g && in->g == in->b)
+ out->r = out->g = out->b = ilinear_g22(in->g);
+
+ else
+ out->r = out->g = out->b = u16d(65535 *
+ YfromRGB(g22_to_d[in->r], g22_to_d[in->g], g22_to_d[in->b]));
+
+ out->a = 65535;
+}
+#endif
+
+#if ALLOW_UNUSED_GPC
+/* Gpre: make gAMA 45455 components grayscale and linear and premultiply by
+ * alpha.
+ */
+static void
+gpc_Gpre(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+
+ if (in->r == in->g && in->g == in->b)
+ out->r = out->g = out->b = ilineara_g22(in->g, in->a);
+
+ else
+ out->r = out->g = out->b = u16d(in->a * 257 *
+ YfromRGB(g22_to_d[in->r], g22_to_d[in->g], g22_to_d[in->b]));
+
+ out->a = 257 * in->a;
+}
+#endif
+
+#if ALLOW_UNUSED_GPC
+/* Gpr': as 'Gpre' but alpha := 65535 */
+static void
+gpc_Gprq(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+
+ if (in->r == in->g && in->g == in->b)
+ out->r = out->g = out->b = ilineara_g22(in->g, in->a);
+
+ else
+ out->r = out->g = out->b = u16d(in->a * 257 *
+ YfromRGB(g22_to_d[in->r], g22_to_d[in->g], g22_to_d[in->b]));
+
+ out->a = 65535;
+}
+#endif
+
+/* 16-bit to 8-bit conversions */
+/* sRGB: convert linear components to sRGB, alpha := 255 */
+static void
+gpc_sRGB(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+
+ out->r = isRGB(in->r);
+
+ if (in->g == in->r)
+ {
+ out->g = out->r;
+
+ if (in->b == in->r)
+ out->b = out->r;
+
+ else
+ out->b = isRGB(in->b);
+ }
+
+ else
+ {
+ out->g = isRGB(in->g);
+
+ if (in->b == in->r)
+ out->b = out->r;
+
+ else if (in->b == in->g)
+ out->b = out->g;
+
+ else
+ out->b = isRGB(in->b);
+ }
+
+ out->a = 255;
+}
+
+/* unpg: unpremultiply gray component and convert to sRGB (scale alpha) */
+static void
+gpc_unpg(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+
+ if (in->a <= 128)
+ {
+ out->r = out->g = out->b = 255;
+ out->a = 0;
+ }
+
+ else
+ {
+ out->r = out->g = out->b = sRGB((double)in->g / in->a);
+ out->a = u8d(in->a / 257.);
+ }
+}
+
+/* unpc: unpremultiply color components and convert to sRGB (scale alpha) */
+static void
+gpc_unpc(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+
+ if (in->a <= 128)
+ {
+ out->r = out->g = out->b = 255;
+ out->a = 0;
+ }
+
+ else
+ {
+ out->r = sRGB((double)in->r / in->a);
+ out->g = sRGB((double)in->g / in->a);
+ out->b = sRGB((double)in->b / in->a);
+ out->a = u8d(in->a / 257.);
+ }
+}
+
+/* b16g: composite linear onto gray background and convert the result to sRGB */
+static void
+gpc_b16g(Pixel *out, const Pixel *in, const Background *back)
+{
+ if (in->a <= 0)
+ out->r = out->g = out->b = back->ig;
+
+ else
+ {
+ double a = in->a/65535.;
+ double a1 = 1-a;
+
+ a /= 65535;
+ out->r = out->g = out->b = sRGB(in->g * a + back->dg * a1);
+ }
+
+ out->a = 255;
+}
+
+/* b16c: composite linear onto color background and convert the result to sRGB*/
+static void
+gpc_b16c(Pixel *out, const Pixel *in, const Background *back)
+{
+ if (in->a <= 0)
+ {
+ out->r = back->ir;
+ out->g = back->ig;
+ out->b = back->ib;
+ }
+
+ else
+ {
+ double a = in->a/65535.;
+ double a1 = 1-a;
+
+ a /= 65535;
+ out->r = sRGB(in->r * a + back->dr * a1);
+ out->g = sRGB(in->g * a + back->dg * a1);
+ out->b = sRGB(in->b * a + back->db * a1);
+ }
+
+ out->a = 255;
+}
+
+/* sG: convert linear RGB to sRGB grayscale */
+static void
+gpc_sG(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+
+ out->r = out->g = out->b = sRGB(YfromRGBint(in->r, in->g, in->b)/65535);
+ out->a = 255;
+}
+
+/* sGp: unpremultiply RGB then convert to sRGB grayscale */
+static void
+gpc_sGp(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+
+ if (in->a <= 128)
+ {
+ out->r = out->g = out->b = 255;
+ out->a = 0;
+ }
+
+ else
+ {
+ out->r = out->g = out->b = sRGB(YfromRGBint(in->r, in->g, in->b)/in->a);
+ out->a = u8d(in->a / 257.);
+ }
+}
+
+/* sCp: unpremultiply RGB then convert to sRGB */
+static void
+gpc_sCp(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+
+ if (in->a <= 128)
+ {
+ out->r = out->g = out->b = 255;
+ out->a = 0;
+ }
+
+ else
+ {
+ out->r = sRGB((double)in->r / in->a);
+ out->g = sRGB((double)in->g / in->a);
+ out->b = sRGB((double)in->b / in->a);
+ out->a = u8d(in->a / 257.);
+ }
+}
+
+/* gb16: composite linear onto background and convert to sRGB grayscale */
+/* (order doesn't matter, the composite and grayscale operations permute) */
+static void
+gpc_gb16(Pixel *out, const Pixel *in, const Background *back)
+{
+ if (in->a <= 0)
+ out->r = out->g = out->b = back->ig;
+
+ else if (in->a >= 65535)
+ out->r = out->g = out->b = isRGB(in->g);
+
+ else
+ {
+ double a = in->a / 65535.;
+ double a1 = 1-a;
+
+ a /= 65535;
+ out->r = out->g = out->b = sRGB(in->g * a + back->dg * a1);
+ }
+
+ out->a = 255;
+}
+
+/* cb16: composite linear onto background and convert to sRGB */
+static void
+gpc_cb16(Pixel *out, const Pixel *in, const Background *back)
+{
+ if (in->a <= 0)
+ {
+ out->r = back->ir;
+ out->g = back->ig;
+ out->b = back->ib;
+ }
+
+ else if (in->a >= 65535)
+ {
+ out->r = isRGB(in->r);
+ out->g = isRGB(in->g);
+ out->b = isRGB(in->b);
+ }
+
+ else
+ {
+ double a = in->a / 65535.;
+ double a1 = 1-a;
+
+ a /= 65535;
+ out->r = sRGB(in->r * a + back->dr * a1);
+ out->g = sRGB(in->g * a + back->dg * a1);
+ out->b = sRGB(in->b * a + back->db * a1);
+ }
+
+ out->a = 255;
+}
+
+/* 16-bit to 16-bit conversions */
+/* A: set alpha to 65535 */
+static void
+gpc_A(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+ out->r = in->r;
+ out->g = in->g;
+ out->b = in->b;
+ out->a = 65535;
+}
+
+/* g16: convert linear RGB to linear grayscale (alpha := 65535) */
+static void
+gpc_g16(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+ out->r = out->g = out->b = u16d(YfromRGBint(in->r, in->g, in->b));
+ out->a = 65535;
+}
+
+/* g16': as 'g16' but alpha is unchanged */
+static void
+gpc_g16q(Pixel *out, const Pixel *in, const Background *back)
+{
+ (void)back;
+ out->r = out->g = out->b = u16d(YfromRGBint(in->r, in->g, in->b));
+ out->a = in->a;
+}
+
+#if ALLOW_UNUSED_GPC
+/* Unused functions (to hide them from GCC unused function warnings) */
+void (* const gpc_unused[])
+ (Pixel *out, const Pixel *in, const Background *back) =
+{
+ gpc_Pre, gpc_Preq, gpc_Glin, gpc_Gpre, gpc_Gprq, gpc_nop8, gpc_nop6
+};
+#endif
+
+/* OUT: ----- 8-bit ----- ----- 16-bit -----
+ * IN G GA RGB RGBA G GA RGB RGBA
+ * 8 G . . . . lin lin lin lin
+ * 8 GA bckg . bckc . pre' pre pre' pre
+ * 8 RGB g8 g8 . . glin glin lin lin
+ * 8 RGBA g8b g8 bckc . gpr' gpre pre' pre
+ * 16 G sRGB sRGB sRGB sRGB . . . .
+ * 16 GA b16g unpg b16c unpc A . A .
+ * 16 RGB sG sG sRGB sRGB g16 g16 . .
+ * 16 RGBA gb16 sGp cb16 sCp g16 g16' A .
+ *
+ * The matrix is held in an array indexed thus:
+ *
+ * gpc_fn[out_format & BASE_FORMATS][in_format & BASE_FORMATS];
+ */
+/* This will produce a compile time error if the FORMAT_FLAG values don't
+ * match the above matrix!
+ */
+#if PNG_FORMAT_FLAG_ALPHA == 1 && PNG_FORMAT_FLAG_COLOR == 2 &&\
+ PNG_FORMAT_FLAG_LINEAR == 4
+static void (* const gpc_fn[8/*in*/][8/*out*/])
+ (Pixel *out, const Pixel *in, const Background *back) =
+{
+/*out: G-8 GA-8 RGB-8 RGBA-8 G-16 GA-16 RGB-16 RGBA-16 */
+ {gpc_noop,gpc_noop,gpc_noop,gpc_noop, gpc_Lin, gpc_Lin, gpc_Lin, gpc_Lin },
+ {gpc_bckg,gpc_noop,gpc_bckc,gpc_noop, gpc_preq,gpc_pre, gpc_preq,gpc_pre },
+ {gpc_g8, gpc_g8, gpc_noop,gpc_noop, gpc_glin,gpc_glin,gpc_lin, gpc_lin },
+ {gpc_g8b, gpc_g8, gpc_bckc,gpc_noop, gpc_gprq,gpc_gpre,gpc_preq,gpc_pre },
+ {gpc_sRGB,gpc_sRGB,gpc_sRGB,gpc_sRGB, gpc_noop,gpc_noop,gpc_noop,gpc_noop},
+ {gpc_b16g,gpc_unpg,gpc_b16c,gpc_unpc, gpc_A, gpc_noop,gpc_A, gpc_noop},
+ {gpc_sG, gpc_sG, gpc_sRGB,gpc_sRGB, gpc_g16, gpc_g16, gpc_noop,gpc_noop},
+ {gpc_gb16,gpc_sGp, gpc_cb16,gpc_sCp, gpc_g16, gpc_g16q,gpc_A, gpc_noop}
+};
+
+/* The array is repeated for the cases where both the input and output are color
+ * mapped because then different algorithms are used.
+ */
+static void (* const gpc_fn_colormapped[8/*in*/][8/*out*/])
+ (Pixel *out, const Pixel *in, const Background *back) =
+{
+/*out: G-8 GA-8 RGB-8 RGBA-8 G-16 GA-16 RGB-16 RGBA-16 */
+ {gpc_noop,gpc_noop,gpc_noop,gpc_noop, gpc_lin, gpc_lin, gpc_lin, gpc_lin },
+ {gpc_bckg,gpc_noop,gpc_bckc,gpc_noop, gpc_preq,gpc_pre, gpc_preq,gpc_pre },
+ {gpc_g8, gpc_g8, gpc_noop,gpc_noop, gpc_glin,gpc_glin,gpc_lin, gpc_lin },
+ {gpc_g8b, gpc_g8, gpc_bckc,gpc_noop, gpc_gprq,gpc_gpre,gpc_preq,gpc_pre },
+ {gpc_sRGB,gpc_sRGB,gpc_sRGB,gpc_sRGB, gpc_noop,gpc_noop,gpc_noop,gpc_noop},
+ {gpc_b16g,gpc_unpg,gpc_b16c,gpc_unpc, gpc_A, gpc_noop,gpc_A, gpc_noop},
+ {gpc_sG, gpc_sG, gpc_sRGB,gpc_sRGB, gpc_g16, gpc_g16, gpc_noop,gpc_noop},
+ {gpc_gb16,gpc_sGp, gpc_cb16,gpc_sCp, gpc_g16, gpc_g16q,gpc_A, gpc_noop}
+};
+
+/* The error arrays record the error in the same matrix; 64 entries, however
+ * the different algorithms used in libpng for colormap and direct conversions
+ * mean that four separate matrices are used (for each combination of
+ * colormapped and direct.)
+ *
+ * In some cases the conversion between sRGB formats goes via a linear
+ * intermediate; an sRGB to linear conversion (as above) is followed by a simple
+ * linear to sRGB step with no other conversions. This is done by a separate
+ * error array from an arbitrary 'in' format to one of the four basic outputs
+ * (since final output is always sRGB not colormapped).
+ *
+ * These arrays may be modified if the --accumulate flag is set during the run;
+ * then instead of logging errors they are simply added in.
+ *
+ * The three entries are currently for transparent, partially transparent and
+ * opaque input pixel values. Notice that alpha should be exact in each case.
+ *
+ * Errors in alpha should only occur when converting from a direct format
+ * to a colormapped format, when alpha is effectively smashed (so large
+ * errors can occur.) There should be no error in the '0' and 'opaque'
+ * values. The fourth entry in the array is used for the alpha error (and it
+ * should always be zero for the 'via linear' case since this is never color
+ * mapped.)
+ *
+ * Mapping to a colormap smashes the colors, it is necessary to have separate
+ * values for these cases because they are much larger; it is very much
+ * impossible to obtain a reasonable result, these are held in
+ * gpc_error_to_colormap.
+ */
+#if PNG_FORMAT_FLAG_COLORMAP == 8 /* extra check also required */
+# include "pngstest-errors.h" /* machine generated */
+#endif /* COLORMAP flag check */
+#endif /* flag checks */
+
+typedef struct
+{
+ /* Basic pixel information: */
+ Image* in_image; /* Input image */
+ const Image* out_image; /* Output image */
+
+ /* 'background' is the value passed to the gpc_ routines, it may be NULL if
+ * it should not be used (*this* program has an error if it crashes as a
+ * result!)
+ */
+ Background background_color;
+ const Background* background;
+
+ /* Precalculated values: */
+ int in_opaque; /* Value of input alpha that is opaque */
+ int is_palette; /* Sample values come from the palette */
+ int accumulate; /* Accumlate component errors (don't log) */
+ int output_8bit; /* Output is 8-bit (else 16-bit) */
+
+ void (*in_gp)(Pixel*, png_const_voidp);
+ void (*out_gp)(Pixel*, png_const_voidp);
+
+ void (*transform)(Pixel *out, const Pixel *in, const Background *back);
+ /* A function to perform the required transform */
+
+ void (*from_linear)(Pixel *out, const Pixel *in, const Background *back);
+ /* For 'via_linear' transforms the final, from linear, step, else NULL */
+
+ png_uint_16 error[4];
+ /* Three error values for transparent, partially transparent and opaque
+ * input pixels (in turn).
+ */
+
+ png_uint_16 *error_ptr;
+ /* Where these are stored in the static array (for 'accumulate') */
+}
+Transform;
+
+/* Return a 'transform' as above for the given format conversion. */
+static void
+transform_from_formats(Transform *result, Image *in_image,
+ const Image *out_image, png_const_colorp background, int via_linear)
+{
+ png_uint_32 in_format, out_format;
+ png_uint_32 in_base, out_base;
+
+ memset(result, 0, sizeof *result);
+
+ /* Store the original images for error messages */
+ result->in_image = in_image;
+ result->out_image = out_image;
+
+ in_format = in_image->image.format;
+ out_format = out_image->image.format;
+
+ if (in_format & PNG_FORMAT_FLAG_LINEAR)
+ result->in_opaque = 65535;
+ else
+ result->in_opaque = 255;
+
+ result->output_8bit = (out_format & PNG_FORMAT_FLAG_LINEAR) == 0;
+
+ result->is_palette = 0; /* set by caller if required */
+ result->accumulate = (in_image->opts & ACCUMULATE) != 0;
+
+ /* The loaders (which need the ordering information) */
+ result->in_gp = get_pixel(in_format);
+ result->out_gp = get_pixel(out_format);
+
+ /* Remove the ordering information: */
+ in_format &= BASE_FORMATS | PNG_FORMAT_FLAG_COLORMAP;
+ in_base = in_format & BASE_FORMATS;
+ out_format &= BASE_FORMATS | PNG_FORMAT_FLAG_COLORMAP;
+ out_base = out_format & BASE_FORMATS;
+
+ if (via_linear)
+ {
+ /* Check for an error in this program: */
+ if (out_format & (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLORMAP))
+ {
+ fprintf(stderr, "internal transform via linear error 0x%x->0x%x\n",
+ in_format, out_format);
+ exit(1);
+ }
+
+ result->transform = gpc_fn[in_base][out_base | PNG_FORMAT_FLAG_LINEAR];
+ result->from_linear = gpc_fn[out_base | PNG_FORMAT_FLAG_LINEAR][out_base];
+ result->error_ptr = gpc_error_via_linear[in_format][out_format];
+ }
+
+ else if (~in_format & out_format & PNG_FORMAT_FLAG_COLORMAP)
+ {
+ /* The input is not colormapped but the output is, the errors will
+ * typically be large (only the grayscale-no-alpha case permits preserving
+ * even 8-bit values.)
+ */
+ result->transform = gpc_fn[in_base][out_base];
+ result->from_linear = NULL;
+ result->error_ptr = gpc_error_to_colormap[in_base][out_base];
+ }
+
+ else
+ {
+ /* The caller handles the colormap->pixel value conversion, so the
+ * transform function just gets a pixel value, however because libpng
+ * currently contains a different implementation for mapping a colormap if
+ * both input and output are colormapped we need different conversion
+ * functions to deal with errors in the libpng implementation.
+ */
+ if (in_format & out_format & PNG_FORMAT_FLAG_COLORMAP)
+ result->transform = gpc_fn_colormapped[in_base][out_base];
+ else
+ result->transform = gpc_fn[in_base][out_base];
+ result->from_linear = NULL;
+ result->error_ptr = gpc_error[in_format][out_format];
+ }
+
+ /* Follow the libpng simplified API rules to work out what to pass to the gpc
+ * routines as a background value, if one is not required pass NULL so that
+ * this program crashes in the even of a programming error.
+ */
+ result->background = NULL; /* default: not required */
+
+ /* Rule 1: background only need be supplied if alpha is to be removed */
+ if (in_format & ~out_format & PNG_FORMAT_FLAG_ALPHA)
+ {
+ /* The input value is 'NULL' to use the background and (otherwise) an sRGB
+ * background color (to use a solid color). The code above uses a fixed
+ * byte value, BUFFER_INIT8, for buffer even for 16-bit output. For
+ * linear (16-bit) output the sRGB background color is ignored; the
+ * composition is always on the background (so BUFFER_INIT8 * 257), except
+ * that for the colormap (i.e. linear colormapped output) black is used.
+ */
+ result->background = &result->background_color;
+
+ if (out_format & PNG_FORMAT_FLAG_LINEAR || via_linear)
+ {
+ if (out_format & PNG_FORMAT_FLAG_COLORMAP)
+ {
+ result->background_color.ir =
+ result->background_color.ig =
+ result->background_color.ib = 0;
+ result->background_color.dr =
+ result->background_color.dg =
+ result->background_color.db = 0;
+ }
+
+ else
+ {
+ result->background_color.ir =
+ result->background_color.ig =
+ result->background_color.ib = BUFFER_INIT8 * 257;
+ result->background_color.dr =
+ result->background_color.dg =
+ result->background_color.db = 0;
+ }
+ }
+
+ else /* sRGB output */
+ {
+ if (background != NULL)
+ {
+ if (out_format & PNG_FORMAT_FLAG_COLOR)
+ {
+ result->background_color.ir = background->red;
+ result->background_color.ig = background->green;
+ result->background_color.ib = background->blue;
+ /* TODO: sometimes libpng uses the power law conversion here, how
+ * to handle this?
+ */
+ result->background_color.dr = sRGB_to_d[background->red];
+ result->background_color.dg = sRGB_to_d[background->green];
+ result->background_color.db = sRGB_to_d[background->blue];
+ }
+
+ else /* grayscale: libpng only looks at 'g' */
+ {
+ result->background_color.ir =
+ result->background_color.ig =
+ result->background_color.ib = background->green;
+ /* TODO: sometimes libpng uses the power law conversion here, how
+ * to handle this?
+ */
+ result->background_color.dr =
+ result->background_color.dg =
+ result->background_color.db = sRGB_to_d[background->green];
+ }
+ }
+
+ else if ((out_format & PNG_FORMAT_FLAG_COLORMAP) == 0)
+ {
+ result->background_color.ir =
+ result->background_color.ig =
+ result->background_color.ib = BUFFER_INIT8;
+ /* TODO: sometimes libpng uses the power law conversion here, how
+ * to handle this?
+ */
+ result->background_color.dr =
+ result->background_color.dg =
+ result->background_color.db = sRGB_to_d[BUFFER_INIT8];
+ }
+
+ /* Else the output is colormapped and a background color must be
+ * provided; if pngstest crashes then that is a bug in this program
+ * (though libpng should png_error as well.)
+ */
+ else
+ result->background = NULL;
+ }
+ }
+
+ if (result->background == NULL)
+ {
+ result->background_color.ir =
+ result->background_color.ig =
+ result->background_color.ib = -1; /* not used */
+ result->background_color.dr =
+ result->background_color.dg =
+ result->background_color.db = 1E30; /* not used */
+ }
+
+
+ /* Copy the error values into the Transform: */
+ result->error[0] = result->error_ptr[0];
+ result->error[1] = result->error_ptr[1];
+ result->error[2] = result->error_ptr[2];
+ result->error[3] = result->error_ptr[3];
+}
+
+
+/* Compare two pixels.
+ *
+ * OLD error values:
+static int error_to_linear = 811; * by experiment *
+static int error_to_linear_grayscale = 424; * by experiment *
+static int error_to_sRGB = 6; * by experiment *
+static int error_to_sRGB_grayscale = 17; * libpng error by calculation +
+ 2 by experiment *
+static int error_in_compose = 2; * by experiment *
+static int error_in_premultiply = 1;
+ *
+ * The following is *just* the result of a round trip from 8-bit sRGB to linear
+ * then back to 8-bit sRGB when it is done by libpng. There are two problems:
+ *
+ * 1) libpng currently uses a 2.2 power law with no linear segment, this results
+ * in instability in the low values and even with 16-bit precision sRGB(1) ends
+ * up mapping to sRGB(0) as a result of rounding in the 16-bit representation.
+ * This gives an error of 1 in the handling of value 1 only.
+ *
+ * 2) libpng currently uses an intermediate 8-bit linear value in gamma
+ * correction of 8-bit values. This results in many more errors, the worse of
+ * which is mapping sRGB(14) to sRGB(0).
+ *
+ * The general 'error_via_linear' is more complex because of pre-multiplication,
+ * this compounds the 8-bit errors according to the alpha value of the pixel.
+ * As a result 256 values are pre-calculated for error_via_linear.
+ */
+#if 0
+static int error_in_libpng_gamma;
+static int error_via_linear[256]; /* Indexed by 8-bit alpha */
+
+static void
+init_error_via_linear(void)
+{
+ int alpha;
+
+ error_via_linear[0] = 255; /* transparent pixel */
+
+ for (alpha=1; alpha<=255; ++alpha)
+ {
+ /* 16-bit values less than 128.5 get rounded to 8-bit 0 and so the worst
+ * case error arises with 16-bit 128.5, work out what sRGB
+ * (non-associated) value generates 128.5; any value less than this is
+ * going to map to 0, so the worst error is floor(value).
+ *
+ * Note that errors are considerably higher (more than a factor of 2)
+ * because libpng uses a simple power law for sRGB data at present.
+ *
+ * Add .1 for arithmetic errors inside libpng.
+ */
+ double v = floor(255*pow(.5/*(128.5 * 255 / 65535)*/ / alpha, 1/2.2)+.1);
+
+ error_via_linear[alpha] = (int)v;
+ }
+
+ /* This is actually 14.99, but, despite the closeness to 15, 14 seems to work
+ * ok in this case.
+ */
+ error_in_libpng_gamma = 14;
+}
+#endif
+
+static void
+print_pixel(char string[64], const Pixel *pixel, png_uint_32 format)
+{
+ switch (format & (PNG_FORMAT_FLAG_ALPHA|PNG_FORMAT_FLAG_COLOR))
+ {
+ case 0:
+ sprintf(string, "%s(%d)", format_names[format], pixel->g);
+ break;
+
+ case PNG_FORMAT_FLAG_ALPHA:
+ sprintf(string, "%s(%d,%d)", format_names[format], pixel->g,
+ pixel->a);
+ break;
+
+ case PNG_FORMAT_FLAG_COLOR:
+ sprintf(string, "%s(%d,%d,%d)", format_names[format],
+ pixel->r, pixel->g, pixel->b);
+ break;
+
+ case PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA:
+ sprintf(string, "%s(%d,%d,%d,%d)", format_names[format],
+ pixel->r, pixel->g, pixel->b, pixel->a);
+ break;
+
+ default:
+ sprintf(string, "invalid-format");
+ break;
+ }
+}
+
+static int
+logpixel(const Transform *transform, png_uint_32 x, png_uint_32 y,
+ const Pixel *in, const Pixel *calc, const Pixel *out, const char *reason)
+{
+ const png_uint_32 in_format = transform->in_image->image.format;
+ const png_uint_32 out_format = transform->out_image->image.format;
+
+ png_uint_32 back_format = out_format & ~PNG_FORMAT_FLAG_ALPHA;
+ const char *via_linear = "";
+
+ char pixel_in[64], pixel_calc[64], pixel_out[64], pixel_loc[64];
+ char background_info[100];
+
+ print_pixel(pixel_in, in, in_format);
+ print_pixel(pixel_calc, calc, out_format);
+ print_pixel(pixel_out, out, out_format);
+
+ if (transform->is_palette)
+ sprintf(pixel_loc, "palette: %lu", (unsigned long)y);
+ else
+ sprintf(pixel_loc, "%lu,%lu", (unsigned long)x, (unsigned long)y);
+
+ if (transform->from_linear != NULL)
+ {
+ via_linear = " (via linear)";
+ /* And as a result the *read* format which did any background processing
+ * was itself linear, so the background color information is also
+ * linear.
+ */
+ back_format |= PNG_FORMAT_FLAG_LINEAR;
+ }
+
+ if (transform->background != NULL)
+ {
+ Pixel back;
+ char pixel_back[64];
+
+ back.r = transform->background->ir;
+ back.g = transform->background->ig;
+ back.b = transform->background->ib;
+ back.a = -1; /* not used */
+
+ print_pixel(pixel_back, &back, back_format);
+ sprintf(background_info, " on background %s", pixel_back);
+ }
+
+ else
+ background_info[0] = 0;
+
+ if (transform->in_image->file_name != transform->out_image->file_name)
+ {
+ char error_buffer[512];
+ sprintf(error_buffer,
+ "(%s) %s error%s:\n %s%s ->\n %s\n not: %s.\n"
+ "Use --preserve and examine: ", pixel_loc, reason, via_linear,
+ pixel_in, background_info, pixel_out, pixel_calc);
+ return logerror(transform->in_image, transform->in_image->file_name,
+ error_buffer, transform->out_image->file_name);
+ }
+
+ else
+ {
+ char error_buffer[512];
+ sprintf(error_buffer,
+ "(%s) %s error%s:\n %s%s ->\n %s\n not: %s.\n"
+ " The error happened when reading the original file with this format.",
+ pixel_loc, reason, via_linear, pixel_in, background_info, pixel_out,
+ pixel_calc);
+ return logerror(transform->in_image, transform->in_image->file_name,
+ error_buffer, "");
+ }
+}
+
+static int
+cmppixel(Transform *transform, png_const_voidp in, png_const_voidp out,
+ png_uint_32 x, png_uint_32 y/*or palette index*/)
+{
+ int maxerr;
+ png_const_charp errmsg;
+ Pixel pixel_in, pixel_calc, pixel_out;
+
+ transform->in_gp(&pixel_in, in);
+
+ if (transform->from_linear == NULL)
+ transform->transform(&pixel_calc, &pixel_in, transform->background);
+
+ else
+ {
+ transform->transform(&pixel_out, &pixel_in, transform->background);
+ transform->from_linear(&pixel_calc, &pixel_out, NULL);
+ }
+
+ transform->out_gp(&pixel_out, out);
+
+ /* Eliminate the case where the input and output values match exactly. */
+ if (pixel_calc.a == pixel_out.a && pixel_calc.r == pixel_out.r &&
+ pixel_calc.g == pixel_out.g && pixel_calc.b == pixel_out.b)
+ return 1;
+
+ /* Eliminate the case where the output pixel is transparent and the output
+ * is 8-bit - any component values are valid. Don't check the input alpha
+ * here to also skip the 16-bit small alpha cases.
+ */
+ if (transform->output_8bit && pixel_calc.a == 0 && pixel_out.a == 0)
+ return 1;
+
+ /* Check for alpha errors first; an alpha error can damage the components too
+ * so avoid spurious checks on components if one is found.
+ */
+ errmsg = NULL;
+ {
+ int err_a = abs(pixel_calc.a-pixel_out.a);
+
+ if (err_a > transform->error[3])
+ {
+ /* If accumulating check the components too */
+ if (transform->accumulate)
+ transform->error[3] = (png_uint_16)err_a;
+
+ else
+ errmsg = "alpha";
+ }
+ }
+
+ /* Now if *either* of the output alphas are 0 but alpha is within tolerance
+ * eliminate the 8-bit component comparison.
+ */
+ if (errmsg == NULL && transform->output_8bit &&
+ (pixel_calc.a == 0 || pixel_out.a == 0))
+ return 1;
+
+ if (errmsg == NULL) /* else just signal an alpha error */
+ {
+ int err_r = abs(pixel_calc.r - pixel_out.r);
+ int err_g = abs(pixel_calc.g - pixel_out.g);
+ int err_b = abs(pixel_calc.b - pixel_out.b);
+ int limit;
+
+ if ((err_r | err_g | err_b) == 0)
+ return 1; /* exact match */
+
+ /* Mismatch on a component, check the input alpha */
+ if (pixel_in.a >= transform->in_opaque)
+ {
+ errmsg = "opaque component";
+ limit = 2; /* opaque */
+ }
+
+ else if (pixel_in.a > 0)
+ {
+ errmsg = "alpha component";
+ limit = 1; /* partially transparent */
+ }
+
+ else
+ {
+ errmsg = "transparent component (background)";
+ limit = 0; /* transparent */
+ }
+
+ maxerr = err_r;
+ if (maxerr < err_g) maxerr = err_g;
+ if (maxerr < err_b) maxerr = err_b;
+
+ if (maxerr <= transform->error[limit])
+ return 1; /* within the error limits */
+
+ /* Handle a component mis-match; log it, just return an error code, or
+ * accumulate it.
+ */
+ if (transform->accumulate)
+ {
+ transform->error[limit] = (png_uint_16)maxerr;
+ return 1; /* to cause the caller to keep going */
+ }
+ }
+
+ /* Failure to match and not accumulating, so the error must be logged. */
+ return logpixel(transform, x, y, &pixel_in, &pixel_calc, &pixel_out, errmsg);
+}
+
+static png_byte
+component_loc(png_byte loc[4], png_uint_32 format)
+{
+ /* Given a format return the number of channels and the location of
+ * each channel.
+ *
+ * The mask 'loc' contains the component offset of the channels in the
+ * following order. Note that if 'format' is grayscale the entries 1-3 must
+ * all contain the location of the gray channel.
+ *
+ * 0: alpha
+ * 1: red or gray
+ * 2: green or gray
+ * 3: blue or gray
+ */
+ png_byte channels;
+
+ if (format & PNG_FORMAT_FLAG_COLOR)
+ {
+ channels = 3;
+
+ loc[2] = 1;
+
+# ifdef PNG_FORMAT_BGR_SUPPORTED
+ if (format & PNG_FORMAT_FLAG_BGR)
+ {
+ loc[1] = 2;
+ loc[3] = 0;
+ }
+
+ else
+# endif
+ {
+ loc[1] = 0;
+ loc[3] = 2;
+ }
+ }
+
+ else
+ {
+ channels = 1;
+ loc[1] = loc[2] = loc[3] = 0;
+ }
+
+ if (format & PNG_FORMAT_FLAG_ALPHA)
+ {
+# ifdef PNG_FORMAT_AFIRST_SUPPORTED
+ if (format & PNG_FORMAT_FLAG_AFIRST)
+ {
+ loc[0] = 0;
+ ++loc[1];
+ ++loc[2];
+ ++loc[3];
+ }
+
+ else
+# endif
+ loc[0] = channels;
+
+ ++channels;
+ }
+
+ else
+ loc[0] = 4; /* not present */
+
+ return channels;
+}
+
+/* Compare two images, the original 'a', which was written out then read back in
+ * to * give image 'b'. The formats may have been changed.
+ */
+static int
+compare_two_images(Image *a, Image *b, int via_linear,
+ png_const_colorp background)
+{
+ ptrdiff_t stridea = a->stride;
+ ptrdiff_t strideb = b->stride;
+ png_const_bytep rowa = a->buffer+16;
+ png_const_bytep rowb = b->buffer+16;
+ const png_uint_32 width = a->image.width;
+ const png_uint_32 height = a->image.height;
+ const png_uint_32 formata = a->image.format;
+ const png_uint_32 formatb = b->image.format;
+ const unsigned int a_sample = PNG_IMAGE_SAMPLE_SIZE(formata);
+ const unsigned int b_sample = PNG_IMAGE_SAMPLE_SIZE(formatb);
+ int alpha_added, alpha_removed;
+ int bchannels;
+ int btoa[4];
+ png_uint_32 y;
+ Transform tr;
+
+ /* This should never happen: */
+ if (width != b->image.width || height != b->image.height)
+ return logerror(a, a->file_name, ": width x height changed: ",
+ b->file_name);
+
+ /* Set up the background and the transform */
+ transform_from_formats(&tr, a, b, background, via_linear);
+
+ /* Find the first row and inter-row space. */
+ if (!(formata & PNG_FORMAT_FLAG_COLORMAP) &&
+ (formata & PNG_FORMAT_FLAG_LINEAR))
+ stridea *= 2;
+
+ if (!(formatb & PNG_FORMAT_FLAG_COLORMAP) &&
+ (formatb & PNG_FORMAT_FLAG_LINEAR))
+ strideb *= 2;
+
+ if (stridea < 0) rowa += (height-1) * (-stridea);
+ if (strideb < 0) rowb += (height-1) * (-strideb);
+
+ /* First shortcut the two colormap case by comparing the image data; if it
+ * matches then we expect the colormaps to match, although this is not
+ * absolutely necessary for an image match. If the colormaps fail to match
+ * then there is a problem in libpng.
+ */
+ if (formata & formatb & PNG_FORMAT_FLAG_COLORMAP)
+ {
+ /* Only check colormap entries that actually exist; */
+ png_const_bytep ppa, ppb;
+ int match;
+ png_byte in_use[256], amax = 0, bmax = 0;
+
+ memset(in_use, 0, sizeof in_use);
+
+ ppa = rowa;
+ ppb = rowb;
+
+ /* Do this the slow way to accumulate the 'in_use' flags, don't break out
+ * of the loop until the end; this validates the color-mapped data to
+ * ensure all pixels are valid color-map indexes.
+ */
+ for (y=0, match=1; y<height && match; ++y, ppa += stridea, ppb += strideb)
+ {
+ png_uint_32 x;
+
+ for (x=0; x<width; ++x)
+ {
+ png_byte bval = ppb[x];
+ png_byte aval = ppa[x];
+
+ if (bval > bmax)
+ bmax = bval;
+
+ if (bval != aval)
+ match = 0;
+
+ in_use[aval] = 1;
+ if (aval > amax)
+ amax = aval;
+ }
+ }
+
+ /* If the buffers match then the colormaps must too. */
+ if (match)
+ {
+ /* Do the color-maps match, entry by entry? Only check the 'in_use'
+ * entries. An error here should be logged as a color-map error.
+ */
+ png_const_bytep a_cmap = (png_const_bytep)a->colormap;
+ png_const_bytep b_cmap = (png_const_bytep)b->colormap;
+ int result = 1; /* match by default */
+
+ /* This is used in logpixel to get the error message correct. */
+ tr.is_palette = 1;
+
+ for (y=0; y<256; ++y, a_cmap += a_sample, b_cmap += b_sample)
+ if (in_use[y])
+ {
+ /* The colormap entries should be valid, but because libpng doesn't
+ * do any checking at present the original image may contain invalid
+ * pixel values. These cause an error here (at present) unless
+ * accumulating errors in which case the program just ignores them.
+ */
+ if (y >= a->image.colormap_entries)
+ {
+ if ((a->opts & ACCUMULATE) == 0)
+ {
+ char pindex[9];
+ sprintf(pindex, "%lu[%lu]", (unsigned long)y,
+ (unsigned long)a->image.colormap_entries);
+ logerror(a, a->file_name, ": bad pixel index: ", pindex);
+ }
+ result = 0;
+ }
+
+ else if (y >= b->image.colormap_entries)
+ {
+ if ((b->opts & ACCUMULATE) == 0)
+ {
+ char pindex[9];
+ sprintf(pindex, "%lu[%lu]", (unsigned long)y,
+ (unsigned long)b->image.colormap_entries);
+ logerror(b, b->file_name, ": bad pixel index: ", pindex);
+ }
+ result = 0;
+ }
+
+ /* All the mismatches are logged here; there can only be 256! */
+ else if (!cmppixel(&tr, a_cmap, b_cmap, 0, y))
+ result = 0;
+ }
+
+ /* If reqested copy the error values back from the Transform. */
+ if (a->opts & ACCUMULATE)
+ {
+ tr.error_ptr[0] = tr.error[0];
+ tr.error_ptr[1] = tr.error[1];
+ tr.error_ptr[2] = tr.error[2];
+ tr.error_ptr[3] = tr.error[3];
+ result = 1; /* force a continue */
+ }
+
+ return result;
+ }
+
+ /* else the image buffers don't match pixel-wise so compare sample values
+ * instead, but first validate that the pixel indexes are in range (but
+ * only if not accumulating, when the error is ignored.)
+ */
+ else if ((a->opts & ACCUMULATE) == 0)
+ {
+ /* Check the original image first,
+ * TODO: deal with input images with bad pixel values?
+ */
+ if (amax >= a->image.colormap_entries)
+ {
+ char pindex[9];
+ sprintf(pindex, "%d[%lu]", amax,
+ (unsigned long)a->image.colormap_entries);
+ return logerror(a, a->file_name, ": bad pixel index: ", pindex);
+ }
+
+ else if (bmax >= b->image.colormap_entries)
+ {
+ char pindex[9];
+ sprintf(pindex, "%d[%lu]", bmax,
+ (unsigned long)b->image.colormap_entries);
+ return logerror(b, b->file_name, ": bad pixel index: ", pindex);
+ }
+ }
+ }
+
+ /* We can directly compare pixel values without the need to use the read
+ * or transform support (i.e. a memory compare) if:
+ *
+ * 1) The bit depth has not changed.
+ * 2) RGB to grayscale has not been done (the reverse is ok; we just compare
+ * the three RGB values to the original grayscale.)
+ * 3) An alpha channel has not been removed from an 8-bit format, or the
+ * 8-bit alpha value of the pixel was 255 (opaque).
+ *
+ * If an alpha channel has been *added* then it must have the relevant opaque
+ * value (255 or 65535).
+ *
+ * The fist two the tests (in the order given above) (using the boolean
+ * equivalence !a && !b == !(a || b))
+ */
+ if (!(((formata ^ formatb) & PNG_FORMAT_FLAG_LINEAR) |
+ (formata & (formatb ^ PNG_FORMAT_FLAG_COLOR) & PNG_FORMAT_FLAG_COLOR)))
+ {
+ /* Was an alpha channel changed? */
+ const png_uint_32 alpha_changed = (formata ^ formatb) &
+ PNG_FORMAT_FLAG_ALPHA;
+
+ /* Was an alpha channel removed? (The third test.) If so the direct
+ * comparison is only possible if the input alpha is opaque.
+ */
+ alpha_removed = (formata & alpha_changed) != 0;
+
+ /* Was an alpha channel added? */
+ alpha_added = (formatb & alpha_changed) != 0;
+
+ /* The channels may have been moved between input and output, this finds
+ * out how, recording the result in the btoa array, which says where in
+ * 'a' to find each channel of 'b'. If alpha was added then btoa[alpha]
+ * ends up as 4 (and is not used.)
+ */
+ {
+ int i;
+ png_byte aloc[4];
+ png_byte bloc[4];
+
+ /* The following are used only if the formats match, except that
+ * 'bchannels' is a flag for matching formats. btoa[x] says, for each
+ * channel in b, where to find the corresponding value in a, for the
+ * bchannels. achannels may be different for a gray to rgb transform
+ * (a will be 1 or 2, b will be 3 or 4 channels.)
+ */
+ (void)component_loc(aloc, formata);
+ bchannels = component_loc(bloc, formatb);
+
+ /* Hence the btoa array. */
+ for (i=0; i<4; ++i) if (bloc[i] < 4)
+ btoa[bloc[i]] = aloc[i]; /* may be '4' for alpha */
+
+ if (alpha_added)
+ alpha_added = bloc[0]; /* location of alpha channel in image b */
+
+ else
+ alpha_added = 4; /* Won't match an image b channel */
+
+ if (alpha_removed)
+ alpha_removed = aloc[0]; /* location of alpha channel in image a */
+
+ else
+ alpha_removed = 4;
+ }
+ }
+
+ else
+ {
+ /* Direct compare is not possible, cancel out all the corresponding local
+ * variables.
+ */
+ bchannels = 0;
+ alpha_removed = alpha_added = 4;
+ btoa[3] = btoa[2] = btoa[1] = btoa[0] = 4; /* 4 == not present */
+ }
+
+ for (y=0; y<height; ++y, rowa += stridea, rowb += strideb)
+ {
+ png_const_bytep ppa, ppb;
+ png_uint_32 x;
+
+ for (x=0, ppa=rowa, ppb=rowb; x<width; ++x)
+ {
+ png_const_bytep psa, psb;
+
+ if (formata & PNG_FORMAT_FLAG_COLORMAP)
+ psa = (png_const_bytep)a->colormap + a_sample * *ppa++;
+ else
+ psa = ppa, ppa += a_sample;
+
+ if (formatb & PNG_FORMAT_FLAG_COLORMAP)
+ psb = (png_const_bytep)b->colormap + b_sample * *ppb++;
+ else
+ psb = ppb, ppb += b_sample;
+
+ /* Do the fast test if possible. */
+ if (bchannels)
+ {
+ /* Check each 'b' channel against either the corresponding 'a'
+ * channel or the opaque alpha value, as appropriate. If
+ * alpha_removed value is set (not 4) then also do this only if the
+ * 'a' alpha channel (alpha_removed) is opaque; only relevant for
+ * the 8-bit case.
+ */
+ if (formatb & PNG_FORMAT_FLAG_LINEAR) /* 16-bit checks */
+ {
+ png_const_uint_16p pua = aligncastconst(png_const_uint_16p, psa);
+ png_const_uint_16p pub = aligncastconst(png_const_uint_16p, psb);
+
+ switch (bchannels)
+ {
+ case 4:
+ if (pua[btoa[3]] != pub[3]) break;
+ case 3:
+ if (pua[btoa[2]] != pub[2]) break;
+ case 2:
+ if (pua[btoa[1]] != pub[1]) break;
+ case 1:
+ if (pua[btoa[0]] != pub[0]) break;
+ if (alpha_added != 4 && pub[alpha_added] != 65535) break;
+ continue; /* x loop */
+ default:
+ break; /* impossible */
+ }
+ }
+
+ else if (alpha_removed == 4 || psa[alpha_removed] == 255)
+ {
+ switch (bchannels)
+ {
+ case 4:
+ if (psa[btoa[3]] != psb[3]) break;
+ case 3:
+ if (psa[btoa[2]] != psb[2]) break;
+ case 2:
+ if (psa[btoa[1]] != psb[1]) break;
+ case 1:
+ if (psa[btoa[0]] != psb[0]) break;
+ if (alpha_added != 4 && psb[alpha_added] != 255) break;
+ continue; /* x loop */
+ default:
+ break; /* impossible */
+ }
+ }
+ }
+
+ /* If we get to here the fast match failed; do the slow match for this
+ * pixel.
+ */
+ if (!cmppixel(&tr, psa, psb, x, y) && (a->opts & KEEP_GOING) == 0)
+ return 0; /* error case */
+ }
+ }
+
+ /* If reqested copy the error values back from the Transform. */
+ if (a->opts & ACCUMULATE)
+ {
+ tr.error_ptr[0] = tr.error[0];
+ tr.error_ptr[1] = tr.error[1];
+ tr.error_ptr[2] = tr.error[2];
+ tr.error_ptr[3] = tr.error[3];
+ }
+
+ return 1;
+}
+
+/* Read the file; how the read gets done depends on which of input_file and
+ * input_memory have been set.
+ */
+static int
+read_file(Image *image, png_uint_32 format, png_const_colorp background)
+{
+ memset(&image->image, 0, sizeof image->image);
+ image->image.version = PNG_IMAGE_VERSION;
+
+ if (image->input_memory != NULL)
+ {
+ if (!png_image_begin_read_from_memory(&image->image, image->input_memory,
+ image->input_memory_size))
+ return logerror(image, "memory init: ", image->file_name, "");
+ }
+
+# ifdef PNG_STDIO_SUPPORTED
+ else if (image->input_file != NULL)
+ {
+ if (!png_image_begin_read_from_stdio(&image->image, image->input_file))
+ return logerror(image, "stdio init: ", image->file_name, "");
+ }
+
+ else
+ {
+ if (!png_image_begin_read_from_file(&image->image, image->file_name))
+ return logerror(image, "file init: ", image->file_name, "");
+ }
+# else
+ else
+ {
+ return logerror(image, "unsupported file/stdio init: ",
+ image->file_name, "");
+ }
+# endif
+
+ /* This must be set after the begin_read call: */
+ if (image->opts & sRGB_16BIT)
+ image->image.flags |= PNG_IMAGE_FLAG_16BIT_sRGB;
+
+ /* Have an initialized image with all the data we need plus, maybe, an
+ * allocated file (myfile) or buffer (mybuffer) that need to be freed.
+ */
+ {
+ int result;
+ png_uint_32 image_format;
+
+ /* Print both original and output formats. */
+ image_format = image->image.format;
+
+ if (image->opts & VERBOSE)
+ {
+ printf("%s %lu x %lu %s -> %s", image->file_name,
+ (unsigned long)image->image.width,
+ (unsigned long)image->image.height,
+ format_names[image_format & FORMAT_MASK],
+ (format & FORMAT_NO_CHANGE) != 0 || image->image.format == format
+ ? "no change" : format_names[format & FORMAT_MASK]);
+
+ if (background != NULL)
+ printf(" background(%d,%d,%d)\n", background->red,
+ background->green, background->blue);
+ else
+ printf("\n");
+
+ fflush(stdout);
+ }
+
+ /* 'NO_CHANGE' combined with the color-map flag forces the base format
+ * flags to be set on read to ensure that the original representation is
+ * not lost in the pass through a colormap format.
+ */
+ if ((format & FORMAT_NO_CHANGE) != 0)
+ {
+ if ((format & PNG_FORMAT_FLAG_COLORMAP) != 0 &&
+ (image_format & PNG_FORMAT_FLAG_COLORMAP) != 0)
+ format = (image_format & ~BASE_FORMATS) | (format & BASE_FORMATS);
+
+ else
+ format = image_format;
+ }
+
+ image->image.format = format;
+
+ image->stride = PNG_IMAGE_ROW_STRIDE(image->image) + image->stride_extra;
+ allocbuffer(image);
+
+ result = png_image_finish_read(&image->image, background,
+ image->buffer+16, (png_int_32)image->stride, image->colormap);
+
+ checkbuffer(image, image->file_name);
+
+ if (result)
+ return checkopaque(image);
+
+ else
+ return logerror(image, image->file_name, ": image read failed", "");
+ }
+}
+
+/* Reads from a filename, which must be in image->file_name, but uses
+ * image->opts to choose the method. The file is always read in its native
+ * format (the one the simplified API suggests).
+ */
+static int
+read_one_file(Image *image)
+{
+ if (!(image->opts & READ_FILE) || (image->opts & USE_STDIO))
+ {
+ /* memory or stdio. */
+ FILE *f = fopen(image->file_name, "rb");
+
+ if (f != NULL)
+ {
+ if (image->opts & READ_FILE)
+ image->input_file = f;
+
+ else /* memory */
+ {
+ if (fseek(f, 0, SEEK_END) == 0)
+ {
+ long int cb = ftell(f);
+
+ if (cb > 0)
+ {
+#ifndef __COVERITY__
+ if ((unsigned long int)cb <= (size_t)~(size_t)0)
+#endif
+ {
+ png_bytep b = voidcast(png_bytep, malloc((size_t)cb));
+
+ if (b != NULL)
+ {
+ rewind(f);
+
+ if (fread(b, (size_t)cb, 1, f) == 1)
+ {
+ fclose(f);
+ image->input_memory_size = cb;
+ image->input_memory = b;
+ }
+
+ else
+ {
+ free(b);
+ return logclose(image, f, image->file_name,
+ ": read failed: ");
+ }
+ }
+
+ else
+ return logclose(image, f, image->file_name,
+ ": out of memory: ");
+ }
+
+ else
+ return logclose(image, f, image->file_name,
+ ": file too big for this architecture: ");
+ /* cb is the length of the file as a (long) and
+ * this is greater than the maximum amount of
+ * memory that can be requested from malloc.
+ */
+ }
+
+ else if (cb == 0)
+ return logclose(image, f, image->file_name,
+ ": zero length: ");
+
+ else
+ return logclose(image, f, image->file_name,
+ ": tell failed: ");
+ }
+
+ else
+ return logclose(image, f, image->file_name, ": seek failed: ");
+ }
+ }
+
+ else
+ return logerror(image, image->file_name, ": open failed: ",
+ strerror(errno));
+ }
+
+ return read_file(image, FORMAT_NO_CHANGE, NULL);
+}
+
+#ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
+static int
+write_one_file(Image *output, Image *image, int convert_to_8bit)
+{
+ if (image->opts & FAST_WRITE)
+ image->image.flags |= PNG_IMAGE_FLAG_FAST;
+
+ if (image->opts & USE_STDIO)
+ {
+#ifndef PNG_USE_MKSTEMP
+ FILE *f = tmpfile();
+#else
+ /* Experimental. Coverity says tmpfile() is insecure because it
+ * generates predictable names.
+ *
+ * It is possible to satisfy Coverity by using mkstemp(); however,
+ * any platform supporting mkstemp() undoubtedly has a secure tmpfile()
+ * implementation as well, and doesn't need the fix. Note that
+ * the fix won't work on platforms that don't support mkstemp().
+ *
+ * https://www.securecoding.cert.org/confluence/display/c/
+ * FIO21-C.+Do+not+create+temporary+files+in+shared+directories
+ * says that most historic implementations of tmpfile() provide
+ * only a limited number of possible temporary file names
+ * (usually 26) before file names are recycled. That article also
+ * provides a secure solution that unfortunately depends upon mkstemp().
+ */
+ char tmpfile[] = "pngstest-XXXXXX";
+ int filedes;
+ FILE *f;
+ umask(0177);
+ filedes = mkstemp(tmpfile);
+ if (filedes < 0)
+ f = NULL;
+ else
+ {
+ f = fdopen(filedes,"w+");
+ /* Hide the filename immediately and ensure that the file does
+ * not exist after the program ends
+ */
+ (void) unlink(tmpfile);
+ }
+#endif
+
+ if (f != NULL)
+ {
+ if (png_image_write_to_stdio(&image->image, f, convert_to_8bit,
+ image->buffer+16, (png_int_32)image->stride, image->colormap))
+ {
+ if (fflush(f) == 0)
+ {
+ rewind(f);
+ initimage(output, image->opts, "tmpfile", image->stride_extra);
+ output->input_file = f;
+ if (!checkopaque(image))
+ return 0;
+ }
+
+ else
+ return logclose(image, f, "tmpfile", ": flush: ");
+ }
+
+ else
+ {
+ fclose(f);
+ return logerror(image, "tmpfile", ": write failed", "");
+ }
+ }
+
+ else
+ return logerror(image, "tmpfile", ": open: ", strerror(errno));
+ }
+
+ else
+ {
+ static int counter = 0;
+ char name[32];
+
+ sprintf(name, "%s%d.png", tmpf, ++counter);
+
+ if (png_image_write_to_file(&image->image, name, convert_to_8bit,
+ image->buffer+16, (png_int_32)image->stride, image->colormap))
+ {
+ initimage(output, image->opts, output->tmpfile_name,
+ image->stride_extra);
+ /* Afterwards, or freeimage will delete it! */
+ strcpy(output->tmpfile_name, name);
+
+ if (!checkopaque(image))
+ return 0;
+ }
+
+ else
+ return logerror(image, name, ": write failed", "");
+ }
+
+ /* 'output' has an initialized temporary image, read this back in and compare
+ * this against the original: there should be no change since the original
+ * format was written unmodified unless 'convert_to_8bit' was specified.
+ * However, if the original image was color-mapped, a simple read will zap
+ * the linear, color and maybe alpha flags, this will cause spurious failures
+ * under some circumstances.
+ */
+ if (read_file(output, image->image.format | FORMAT_NO_CHANGE, NULL))
+ {
+ png_uint_32 original_format = image->image.format;
+
+ if (convert_to_8bit)
+ original_format &= ~PNG_FORMAT_FLAG_LINEAR;
+
+ if ((output->image.format & BASE_FORMATS) !=
+ (original_format & BASE_FORMATS))
+ return logerror(image, image->file_name, ": format changed on read: ",
+ output->file_name);
+
+ return compare_two_images(image, output, 0/*via linear*/, NULL);
+ }
+
+ else
+ return logerror(output, output->tmpfile_name,
+ ": read of new file failed", "");
+}
+#endif
+
+static int
+testimage(Image *image, png_uint_32 opts, format_list *pf)
+{
+ int result;
+ Image copy;
+
+ /* Copy the original data, stealing it from 'image' */
+ checkopaque(image);
+ copy = *image;
+
+ copy.opts = opts;
+ copy.buffer = NULL;
+ copy.bufsize = 0;
+ copy.allocsize = 0;
+
+ image->input_file = NULL;
+ image->input_memory = NULL;
+ image->input_memory_size = 0;
+ image->tmpfile_name[0] = 0;
+
+ {
+ png_uint_32 counter;
+ Image output;
+
+ newimage(&output);
+
+ result = 1;
+
+ /* Use the low bit of 'counter' to indicate whether or not to do alpha
+ * removal with a background color or by composting onto the image; this
+ * step gets skipped if it isn't relevant
+ */
+ for (counter=0; counter<2*FORMAT_COUNT; ++counter)
+ if (format_isset(pf, counter >> 1))
+ {
+ png_uint_32 format = counter >> 1;
+
+ png_color background_color;
+ png_colorp background = NULL;
+
+ /* If there is a format change that removes the alpha channel then
+ * the background is relevant. If the output is 8-bit color-mapped
+ * then a background color *must* be provided, otherwise there are
+ * two tests to do - one with a color, the other with NULL. The
+ * NULL test happens second.
+ */
+ if ((counter & 1) == 0)
+ {
+ if ((format & PNG_FORMAT_FLAG_ALPHA) == 0 &&
+ (image->image.format & PNG_FORMAT_FLAG_ALPHA) != 0)
+ {
+ /* Alpha/transparency will be removed, the background is
+ * relevant: make it a color the first time
+ */
+ random_color(&background_color);
+ background = &background_color;
+
+ /* BUT if the output is to a color-mapped 8-bit format then
+ * the background must always be a color, so increment 'counter'
+ * to skip the NULL test.
+ */
+ if ((format & PNG_FORMAT_FLAG_COLORMAP) != 0 &&
+ (format & PNG_FORMAT_FLAG_LINEAR) == 0)
+ ++counter;
+ }
+
+ /* Otherwise an alpha channel is not being eliminated, just leave
+ * background NULL and skip the (counter & 1) NULL test.
+ */
+ else
+ ++counter;
+ }
+ /* else just use NULL for background */
+
+ resetimage(©);
+ copy.opts = opts; /* in case read_file needs to change it */
+
+ result = read_file(©, format, background);
+ if (!result)
+ break;
+
+ /* Make sure the file just read matches the original file. */
+ result = compare_two_images(image, ©, 0/*via linear*/, background);
+ if (!result)
+ break;
+
+# ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
+ /* Write the *copy* just made to a new file to make sure the write
+ * side works ok. Check the conversion to sRGB if the copy is
+ * linear.
+ */
+ output.opts = opts;
+ result = write_one_file(&output, ©, 0/*convert to 8bit*/);
+ if (!result)
+ break;
+
+ /* Validate against the original too; the background is needed here
+ * as well so that compare_two_images knows what color was used.
+ */
+ result = compare_two_images(image, &output, 0, background);
+ if (!result)
+ break;
+
+ if ((format & PNG_FORMAT_FLAG_LINEAR) != 0 &&
+ (format & PNG_FORMAT_FLAG_COLORMAP) == 0)
+ {
+ /* 'output' is linear, convert to the corresponding sRGB format.
+ */
+ output.opts = opts;
+ result = write_one_file(&output, ©, 1/*convert to 8bit*/);
+ if (!result)
+ break;
+
+ /* This may involve a conversion via linear; in the ideal world
+ * this would round-trip correctly, but libpng 1.5.7 is not the
+ * ideal world so allow a drift (error_via_linear).
+ *
+ * 'image' has an alpha channel but 'output' does not then there
+ * will a strip-alpha-channel operation (because 'output' is
+ * linear), handle this by composing on black when doing the
+ * comparison.
+ */
+ result = compare_two_images(image, &output, 1/*via_linear*/,
+ background);
+ if (!result)
+ break;
+ }
+# endif /* PNG_SIMPLIFIED_WRITE_SUPPORTED */
+ }
+
+ freeimage(&output);
+ }
+
+ freeimage(©);
+
+ return result;
+}
+
+static int
+test_one_file(const char *file_name, format_list *formats, png_uint_32 opts,
+ int stride_extra, int log_pass)
+{
+ int result;
+ Image image;
+
+ newimage(&image);
+ initimage(&image, opts, file_name, stride_extra);
+ result = read_one_file(&image);
+ if (result)
+ result = testimage(&image, opts, formats);
+ freeimage(&image);
+
+ /* Ensure that stderr is flushed into any log file */
+ fflush(stderr);
+
+ if (log_pass)
+ {
+ if (result)
+ printf("PASS:");
+
+ else
+ printf("FAIL:");
+
+# ifndef PNG_SIMPLIFIED_WRITE_SUPPORTED
+ printf(" (no write)");
+# endif
+
+ print_opts(opts);
+ printf(" %s\n", file_name);
+ /* stdout may not be line-buffered if it is piped to a file, so: */
+ fflush(stdout);
+ }
+
+ else if (!result)
+ exit(1);
+
+ return result;
+}
+
+int
+main(int argc, char **argv)
+{
+ png_uint_32 opts = FAST_WRITE;
+ format_list formats;
+ const char *touch = NULL;
+ int log_pass = 0;
+ int redundant = 0;
+ int stride_extra = 0;
+ int retval = 0;
+ int c;
+
+ init_sRGB_to_d();
+#if 0
+ init_error_via_linear();
+#endif
+ format_init(&formats);
+
+ for (c=1; c<argc; ++c)
+ {
+ const char *arg = argv[c];
+
+ if (strcmp(arg, "--log") == 0)
+ log_pass = 1;
+ else if (strcmp(arg, "--fresh") == 0)
+ {
+ memset(gpc_error, 0, sizeof gpc_error);
+ memset(gpc_error_via_linear, 0, sizeof gpc_error_via_linear);
+ }
+ else if (strcmp(arg, "--file") == 0)
+# ifdef PNG_STDIO_SUPPORTED
+ opts |= READ_FILE;
+# else
+ return 77; /* skipped: no support */
+# endif
+ else if (strcmp(arg, "--memory") == 0)
+ opts &= ~READ_FILE;
+ else if (strcmp(arg, "--stdio") == 0)
+# ifdef PNG_STDIO_SUPPORTED
+ opts |= USE_STDIO;
+# else
+ return 77; /* skipped: no support */
+# endif
+ else if (strcmp(arg, "--name") == 0)
+ opts &= ~USE_STDIO;
+ else if (strcmp(arg, "--verbose") == 0)
+ opts |= VERBOSE;
+ else if (strcmp(arg, "--quiet") == 0)
+ opts &= ~VERBOSE;
+ else if (strcmp(arg, "--preserve") == 0)
+ opts |= KEEP_TMPFILES;
+ else if (strcmp(arg, "--nopreserve") == 0)
+ opts &= ~KEEP_TMPFILES;
+ else if (strcmp(arg, "--keep-going") == 0)
+ opts |= KEEP_GOING;
+ else if (strcmp(arg, "--fast") == 0)
+ opts |= FAST_WRITE;
+ else if (strcmp(arg, "--slow") == 0)
+ opts &= ~FAST_WRITE;
+ else if (strcmp(arg, "--accumulate") == 0)
+ opts |= ACCUMULATE;
+ else if (strcmp(arg, "--redundant") == 0)
+ redundant = 1;
+ else if (strcmp(arg, "--stop") == 0)
+ opts &= ~KEEP_GOING;
+ else if (strcmp(arg, "--strict") == 0)
+ opts |= STRICT;
+ else if (strcmp(arg, "--sRGB-16bit") == 0)
+ opts |= sRGB_16BIT;
+ else if (strcmp(arg, "--linear-16bit") == 0)
+ opts &= ~sRGB_16BIT;
+ else if (strcmp(arg, "--tmpfile") == 0)
+ {
+ if (c+1 < argc)
+ {
+ if (strlen(argv[++c]) >= sizeof tmpf)
+ {
+ fflush(stdout);
+ fprintf(stderr, "%s: %s is too long for a temp file prefix\n",
+ argv[0], argv[c]);
+ exit(99);
+ }
+
+ /* Safe: checked above */
+ strncpy(tmpf, argv[c], sizeof (tmpf)-1);
+ }
+
+ else
+ {
+ fflush(stdout);
+ fprintf(stderr, "%s: %s requires a temporary file prefix\n",
+ argv[0], arg);
+ exit(99);
+ }
+ }
+ else if (strcmp(arg, "--touch") == 0)
+ {
+ if (c+1 < argc)
+ touch = argv[++c];
+
+ else
+ {
+ fflush(stdout);
+ fprintf(stderr, "%s: %s requires a file name argument\n",
+ argv[0], arg);
+ exit(99);
+ }
+ }
+ else if (arg[0] == '+')
+ {
+ png_uint_32 format = formatof(arg+1);
+
+ if (format > FORMAT_COUNT)
+ exit(99);
+
+ format_set(&formats, format);
+ }
+ else if (arg[0] == '-' && arg[1] != 0 && (arg[1] != '0' || arg[2] != 0))
+ {
+ fflush(stdout);
+ fprintf(stderr, "%s: unknown option: %s\n", argv[0], arg);
+ exit(99);
+ }
+ else
+ {
+ if (format_is_initial(&formats))
+ format_default(&formats, redundant);
+
+ if (arg[0] == '-')
+ {
+ const int term = (arg[1] == '0' ? 0 : '\n');
+ unsigned int ich = 0;
+
+ /* Loop reading files, use a static buffer to simplify this and just
+ * stop if the name gets to long.
+ */
+ static char buffer[4096];
+
+ do
+ {
+ int ch = getchar();
+
+ /* Don't allow '\0' in file names, and terminate with '\n' or,
+ * for -0, just '\0' (use -print0 to find to make this work!)
+ */
+ if (ch == EOF || ch == term || ch == 0)
+ {
+ buffer[ich] = 0;
+
+ if (ich > 0 && !test_one_file(buffer, &formats, opts,
+ stride_extra, log_pass))
+ retval = 1;
+
+ if (ch == EOF)
+ break;
+
+ ich = 0;
+ --ich; /* so that the increment below sets it to 0 again */
+ }
+
+ else
+ buffer[ich] = (char)ch;
+ } while (++ich < sizeof buffer);
+
+ if (ich)
+ {
+ buffer[32] = 0;
+ buffer[4095] = 0;
+ fprintf(stderr, "%s...%s: file name too long\n", buffer,
+ buffer+(4096-32));
+ exit(99);
+ }
+ }
+
+ else if (!test_one_file(arg, &formats, opts, stride_extra, log_pass))
+ retval = 1;
+ }
+ }
+
+ if (opts & ACCUMULATE)
+ {
+ unsigned int in;
+
+ printf("/* contrib/libtests/pngstest-errors.h\n");
+ printf(" *\n");
+ printf(" * BUILT USING:" PNG_HEADER_VERSION_STRING);
+ printf(" *\n");
+ printf(" * This code is released under the libpng license.\n");
+ printf(" * For conditions of distribution and use, see the disclaimer\n");
+ printf(" * and license in png.h\n");
+ printf(" *\n");
+ printf(" * THIS IS A MACHINE GENERATED FILE: do not edit it directly!\n");
+ printf(" * Instead run:\n");
+ printf(" *\n");
+ printf(" * pngstest --accumulate\n");
+ printf(" *\n");
+ printf(" * on as many PNG files as possible; at least PNGSuite and\n");
+ printf(" * contrib/libtests/testpngs.\n");
+ printf(" */\n");
+
+ printf("static png_uint_16 gpc_error[16/*in*/][16/*out*/][4/*a*/] =\n");
+ printf("{\n");
+ for (in=0; in<16; ++in)
+ {
+ unsigned int out;
+ printf(" { /* input: %s */\n ", format_names[in]);
+ for (out=0; out<16; ++out)
+ {
+ unsigned int alpha;
+ printf(" {");
+ for (alpha=0; alpha<4; ++alpha)
+ {
+ printf(" %d", gpc_error[in][out][alpha]);
+ if (alpha < 3) putchar(',');
+ }
+ printf(" }");
+ if (out < 15)
+ {
+ putchar(',');
+ if (out % 4 == 3) printf("\n ");
+ }
+ }
+ printf("\n }");
+
+ if (in < 15)
+ putchar(',');
+ else
+ putchar('\n');
+ }
+ printf("};\n");
+
+ printf("static png_uint_16 gpc_error_via_linear[16][4/*out*/][4] =\n");
+ printf("{\n");
+ for (in=0; in<16; ++in)
+ {
+ unsigned int out;
+ printf(" { /* input: %s */\n ", format_names[in]);
+ for (out=0; out<4; ++out)
+ {
+ unsigned int alpha;
+ printf(" {");
+ for (alpha=0; alpha<4; ++alpha)
+ {
+ printf(" %d", gpc_error_via_linear[in][out][alpha]);
+ if (alpha < 3) putchar(',');
+ }
+ printf(" }");
+ if (out < 3)
+ putchar(',');
+ }
+ printf("\n }");
+
+ if (in < 15)
+ putchar(',');
+ else
+ putchar('\n');
+ }
+ printf("};\n");
+
+ printf("static png_uint_16 gpc_error_to_colormap[8/*i*/][8/*o*/][4] =\n");
+ printf("{\n");
+ for (in=0; in<8; ++in)
+ {
+ unsigned int out;
+ printf(" { /* input: %s */\n ", format_names[in]);
+ for (out=0; out<8; ++out)
+ {
+ unsigned int alpha;
+ printf(" {");
+ for (alpha=0; alpha<4; ++alpha)
+ {
+ printf(" %d", gpc_error_to_colormap[in][out][alpha]);
+ if (alpha < 3) putchar(',');
+ }
+ printf(" }");
+ if (out < 7)
+ {
+ putchar(',');
+ if (out % 4 == 3) printf("\n ");
+ }
+ }
+ printf("\n }");
+
+ if (in < 7)
+ putchar(',');
+ else
+ putchar('\n');
+ }
+ printf("};\n");
+ printf("/* END MACHINE GENERATED */\n");
+ }
+
+ if (retval == 0 && touch != NULL)
+ {
+ FILE *fsuccess = fopen(touch, "wt");
+
+ if (fsuccess != NULL)
+ {
+ int error = 0;
+ fprintf(fsuccess, "PNG simple API tests succeeded\n");
+ fflush(fsuccess);
+ error = ferror(fsuccess);
+
+ if (fclose(fsuccess) || error)
+ {
+ fflush(stdout);
+ fprintf(stderr, "%s: write failed\n", touch);
+ exit(99);
+ }
+ }
+
+ else
+ {
+ fflush(stdout);
+ fprintf(stderr, "%s: open failed\n", touch);
+ exit(99);
+ }
+ }
+
+ return retval;
+}
+
+#else /* !PNG_SIMPLIFIED_READ_SUPPORTED */
+int main(void)
+{
+ fprintf(stderr, "pngstest: no read support in libpng, test skipped\n");
+ /* So the test is skipped: */
+ return 77;
+}
+#endif /* PNG_SIMPLIFIED_READ_SUPPORTED */
diff --git a/libpng/contrib/libtests/pngunknown.c b/libpng/contrib/libtests/pngunknown.c
new file mode 100644
index 0000000..0d52ff8
--- /dev/null
+++ b/libpng/contrib/libtests/pngunknown.c
@@ -0,0 +1,1261 @@
+
+/* pngunknown.c - test the read side unknown chunk handling
+ *
+ * Last changed in libpng 1.6.10 [March 6, 2014]
+ * Copyright (c) 2014 Glenn Randers-Pehrson
+ * Written by John Cunningham Bowler
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * NOTES:
+ * This is a C program that is intended to be linked against libpng. It
+ * allows the libpng unknown handling code to be tested by interpreting
+ * arguments to save or discard combinations of chunks. The program is
+ * currently just a minimal validation for the built-in libpng facilities.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <setjmp.h>
+
+/* Define the following to use this test against your installed libpng, rather
+ * than the one being built here:
+ */
+#ifdef PNG_FREESTANDING_TESTS
+# include <png.h>
+#else
+# include "../../png.h"
+#endif
+
+/* Since this program tests the ability to change the unknown chunk handling
+ * these must be defined:
+ */
+#if defined(PNG_SET_UNKNOWN_CHUNKS_SUPPORTED) &&\
+ defined(PNG_READ_SUPPORTED)
+
+/* One of these must be defined to allow us to find out what happened. It is
+ * still useful to set unknown chunk handling without either of these in order
+ * to cause *known* chunks to be discarded. This can be a significant
+ * efficiency gain, but it can't really be tested here.
+ */
+#if defined(PNG_READ_USER_CHUNKS_SUPPORTED) ||\
+ defined(PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED)
+
+#if PNG_LIBPNG_VER < 10500
+/* This deliberately lacks the PNG_CONST. */
+typedef png_byte *png_const_bytep;
+
+/* This is copied from 1.5.1 png.h: */
+#define PNG_INTERLACE_ADAM7_PASSES 7
+#define PNG_PASS_START_ROW(pass) (((1U&~(pass))<<(3-((pass)>>1)))&7)
+#define PNG_PASS_START_COL(pass) (((1U& (pass))<<(3-(((pass)+1)>>1)))&7)
+#define PNG_PASS_ROW_SHIFT(pass) ((pass)>2?(8-(pass))>>1:3)
+#define PNG_PASS_COL_SHIFT(pass) ((pass)>1?(7-(pass))>>1:3)
+#define PNG_PASS_ROWS(height, pass) (((height)+(((1<<PNG_PASS_ROW_SHIFT(pass))\
+ -1)-PNG_PASS_START_ROW(pass)))>>PNG_PASS_ROW_SHIFT(pass))
+#define PNG_PASS_COLS(width, pass) (((width)+(((1<<PNG_PASS_COL_SHIFT(pass))\
+ -1)-PNG_PASS_START_COL(pass)))>>PNG_PASS_COL_SHIFT(pass))
+#define PNG_ROW_FROM_PASS_ROW(yIn, pass) \
+ (((yIn)<<PNG_PASS_ROW_SHIFT(pass))+PNG_PASS_START_ROW(pass))
+#define PNG_COL_FROM_PASS_COL(xIn, pass) \
+ (((xIn)<<PNG_PASS_COL_SHIFT(pass))+PNG_PASS_START_COL(pass))
+#define PNG_PASS_MASK(pass,off) ( \
+ ((0x110145AFU>>(((7-(off))-(pass))<<2)) & 0xFU) | \
+ ((0x01145AF0U>>(((7-(off))-(pass))<<2)) & 0xF0U))
+#define PNG_ROW_IN_INTERLACE_PASS(y, pass) \
+ ((PNG_PASS_MASK(pass,0) >> ((y)&7)) & 1)
+#define PNG_COL_IN_INTERLACE_PASS(x, pass) \
+ ((PNG_PASS_MASK(pass,1) >> ((x)&7)) & 1)
+
+/* These are needed too for the default build: */
+#define PNG_WRITE_16BIT_SUPPORTED
+#define PNG_READ_16BIT_SUPPORTED
+
+/* This comes from pnglibconf.h afer 1.5: */
+#define PNG_FP_1 100000
+#define PNG_GAMMA_THRESHOLD_FIXED\
+ ((png_fixed_point)(PNG_GAMMA_THRESHOLD * PNG_FP_1))
+#endif
+
+#if PNG_LIBPNG_VER < 10600
+ /* 1.6.0 constifies many APIs. The following exists to allow pngvalid to be
+ * compiled against earlier versions.
+ */
+# define png_const_structp png_structp
+#endif
+
+#if PNG_LIBPNG_VER < 10700
+ /* Copied from libpng 1.7.0 png.h */
+#define PNG_u2(b1, b2) (((unsigned int)(b1) << 8) + (b2))
+
+#define PNG_U16(b1, b2) ((png_uint_16)PNG_u2(b1, b2))
+#define PNG_U32(b1, b2, b3, b4)\
+ (((png_uint_32)PNG_u2(b1, b2) << 16) + PNG_u2(b3, b4))
+
+/* Constants for known chunk types.
+ */
+#define png_IDAT PNG_U32( 73, 68, 65, 84)
+#define png_IEND PNG_U32( 73, 69, 78, 68)
+#define png_IHDR PNG_U32( 73, 72, 68, 82)
+#define png_PLTE PNG_U32( 80, 76, 84, 69)
+#define png_bKGD PNG_U32( 98, 75, 71, 68)
+#define png_cHRM PNG_U32( 99, 72, 82, 77)
+#define png_fRAc PNG_U32(102, 82, 65, 99) /* registered, not defined */
+#define png_gAMA PNG_U32(103, 65, 77, 65)
+#define png_gIFg PNG_U32(103, 73, 70, 103)
+#define png_gIFt PNG_U32(103, 73, 70, 116) /* deprecated */
+#define png_gIFx PNG_U32(103, 73, 70, 120)
+#define png_hIST PNG_U32(104, 73, 83, 84)
+#define png_iCCP PNG_U32(105, 67, 67, 80)
+#define png_iTXt PNG_U32(105, 84, 88, 116)
+#define png_oFFs PNG_U32(111, 70, 70, 115)
+#define png_pCAL PNG_U32(112, 67, 65, 76)
+#define png_pHYs PNG_U32(112, 72, 89, 115)
+#define png_sBIT PNG_U32(115, 66, 73, 84)
+#define png_sCAL PNG_U32(115, 67, 65, 76)
+#define png_sPLT PNG_U32(115, 80, 76, 84)
+#define png_sRGB PNG_U32(115, 82, 71, 66)
+#define png_sTER PNG_U32(115, 84, 69, 82)
+#define png_tEXt PNG_U32(116, 69, 88, 116)
+#define png_tIME PNG_U32(116, 73, 77, 69)
+#define png_tRNS PNG_U32(116, 82, 78, 83)
+#define png_zTXt PNG_U32(122, 84, 88, 116)
+
+/* Test on flag values as defined in the spec (section 5.4): */
+#define PNG_CHUNK_ANCILLARY(c) (1 & ((c) >> 29))
+#define PNG_CHUNK_CRITICAL(c) (!PNG_CHUNK_ANCILLARY(c))
+#define PNG_CHUNK_PRIVATE(c) (1 & ((c) >> 21))
+#define PNG_CHUNK_RESERVED(c) (1 & ((c) >> 13))
+#define PNG_CHUNK_SAFE_TO_COPY(c) (1 & ((c) >> 5))
+
+#endif /* PNG_LIBPNG_VER < 10700 */
+
+#ifdef __cplusplus
+# define this not_the_cpp_this
+# define new not_the_cpp_new
+# define voidcast(type, value) static_cast<type>(value)
+#else
+# define voidcast(type, value) (value)
+#endif /* __cplusplus */
+
+/* Unused formal parameter errors are removed using the following macro which is
+ * expected to have no bad effects on performance.
+ */
+#ifndef UNUSED
+# if defined(__GNUC__) || defined(_MSC_VER)
+# define UNUSED(param) (void)param;
+# else
+# define UNUSED(param)
+# endif
+#endif
+
+/* Types of chunks not known to libpng */
+#define png_vpAg PNG_U32(118, 112, 65, 103)
+
+/* Chunk information */
+#define PNG_INFO_tEXt 0x10000000U
+#define PNG_INFO_iTXt 0x20000000U
+#define PNG_INFO_zTXt 0x40000000U
+
+#define PNG_INFO_sTER 0x01000000U
+#define PNG_INFO_vpAg 0x02000000U
+
+#define ABSENT 0
+#define START 1
+#define END 2
+
+static struct
+{
+ char name[5];
+ png_uint_32 flag;
+ png_uint_32 tag;
+ int unknown; /* Chunk not known to libpng */
+ int all; /* Chunk set by the '-1' option */
+ int position; /* position in pngtest.png */
+ int keep; /* unknown handling setting */
+} chunk_info[] = {
+ /* Critical chunks */
+ { "IDAT", PNG_INFO_IDAT, png_IDAT, 0, 0, START, 0 }, /* must be [0] */
+ { "PLTE", PNG_INFO_PLTE, png_PLTE, 0, 0, ABSENT, 0 },
+
+ /* Non-critical chunks that libpng handles */
+ /* This is a mess but it seems to be the only way to do it - there is no way
+ * to check for a definition outside a #if.
+ */
+ { "bKGD", PNG_INFO_bKGD, png_bKGD,
+# ifdef PNG_READ_bKGD_SUPPORTED
+ 0,
+# else
+ 1,
+# endif
+ 1, START, 0 },
+ { "cHRM", PNG_INFO_cHRM, png_cHRM,
+# ifdef PNG_READ_cHRM_SUPPORTED
+ 0,
+# else
+ 1,
+# endif
+ 1, START, 0 },
+ { "gAMA", PNG_INFO_gAMA, png_gAMA,
+# ifdef PNG_READ_gAMA_SUPPORTED
+ 0,
+# else
+ 1,
+# endif
+ 1, START, 0 },
+ { "hIST", PNG_INFO_hIST, png_hIST,
+# ifdef PNG_READ_hIST_SUPPORTED
+ 0,
+# else
+ 1,
+# endif
+ 1, ABSENT, 0 },
+ { "iCCP", PNG_INFO_iCCP, png_iCCP,
+# ifdef PNG_READ_iCCP_SUPPORTED
+ 0,
+# else
+ 1,
+# endif
+ 1, ABSENT, 0 },
+ { "iTXt", PNG_INFO_iTXt, png_iTXt,
+# ifdef PNG_READ_iTXt_SUPPORTED
+ 0,
+# else
+ 1,
+# endif
+ 1, ABSENT, 0 },
+ { "oFFs", PNG_INFO_oFFs, png_oFFs,
+# ifdef PNG_READ_oFFs_SUPPORTED
+ 0,
+# else
+ 1,
+# endif
+ 1, START, 0 },
+ { "pCAL", PNG_INFO_pCAL, png_pCAL,
+# ifdef PNG_READ_pCAL_SUPPORTED
+ 0,
+# else
+ 1,
+# endif
+ 1, START, 0 },
+ { "pHYs", PNG_INFO_pHYs, png_pHYs,
+# ifdef PNG_READ_pHYs_SUPPORTED
+ 0,
+# else
+ 1,
+# endif
+ 1, START, 0 },
+ { "sBIT", PNG_INFO_sBIT, png_sBIT,
+# ifdef PNG_READ_sBIT_SUPPORTED
+ 0,
+# else
+ 1,
+# endif
+ 1, START, 0 },
+ { "sCAL", PNG_INFO_sCAL, png_sCAL,
+# ifdef PNG_READ_sCAL_SUPPORTED
+ 0,
+# else
+ 1,
+# endif
+ 1, START, 0 },
+ { "sPLT", PNG_INFO_sPLT, png_sPLT,
+# ifdef PNG_READ_sPLT_SUPPORTED
+ 0,
+# else
+ 1,
+# endif
+ 1, ABSENT, 0 },
+ { "sRGB", PNG_INFO_sRGB, png_sRGB,
+# ifdef PNG_READ_sRGB_SUPPORTED
+ 0,
+# else
+ 1,
+# endif
+ 1, START, 0 },
+ { "tEXt", PNG_INFO_tEXt, png_tEXt,
+# ifdef PNG_READ_tEXt_SUPPORTED
+ 0,
+# else
+ 1,
+# endif
+ 1, START, 0 },
+ { "tIME", PNG_INFO_tIME, png_tIME,
+# ifdef PNG_READ_tIME_SUPPORTED
+ 0,
+# else
+ 1,
+# endif
+ 1, START, 0 },
+ { "tRNS", PNG_INFO_tRNS, png_tRNS,
+# ifdef PNG_READ_tRNS_SUPPORTED
+ 0,
+# else
+ 1,
+# endif
+ 0, ABSENT, 0 },
+ { "zTXt", PNG_INFO_zTXt, png_zTXt,
+# ifdef PNG_READ_zTXt_SUPPORTED
+ 0,
+# else
+ 1,
+# endif
+ 1, END, 0 },
+
+ /* No libpng handling */
+ { "sTER", PNG_INFO_sTER, png_sTER, 1, 1, START, 0 },
+ { "vpAg", PNG_INFO_vpAg, png_vpAg, 1, 0, START, 0 },
+};
+
+#define NINFO ((int)((sizeof chunk_info)/(sizeof chunk_info[0])))
+
+static void
+clear_keep(void)
+{
+ int i = NINFO;
+ while (--i >= 0)
+ chunk_info[i].keep = 0;
+}
+
+static int
+find(const char *name)
+{
+ int i = NINFO;
+ while (--i >= 0)
+ {
+ if (memcmp(chunk_info[i].name, name, 4) == 0)
+ break;
+ }
+
+ return i;
+}
+
+static int
+findb(const png_byte *name)
+{
+ int i = NINFO;
+ while (--i >= 0)
+ {
+ if (memcmp(chunk_info[i].name, name, 4) == 0)
+ break;
+ }
+
+ return i;
+}
+
+static int
+find_by_flag(png_uint_32 flag)
+{
+ int i = NINFO;
+
+ while (--i >= 0) if (chunk_info[i].flag == flag) return i;
+
+ fprintf(stderr, "pngunknown: internal error\n");
+ exit(4);
+}
+
+static int
+ancillary(const char *name)
+{
+ return PNG_CHUNK_ANCILLARY(PNG_U32(name[0], name[1], name[2], name[3]));
+}
+
+#ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
+static int
+ancillaryb(const png_byte *name)
+{
+ return PNG_CHUNK_ANCILLARY(PNG_U32(name[0], name[1], name[2], name[3]));
+}
+#endif
+
+/* Type of an error_ptr */
+typedef struct
+{
+ jmp_buf error_return;
+ png_structp png_ptr;
+ png_infop info_ptr, end_ptr;
+ png_uint_32 before_IDAT;
+ png_uint_32 after_IDAT;
+ int error_count;
+ int warning_count;
+ int keep; /* the default value */
+ const char *program;
+ const char *file;
+ const char *test;
+} display;
+
+static const char init[] = "initialization";
+static const char cmd[] = "command line";
+
+static void
+init_display(display *d, const char *program)
+{
+ memset(d, 0, sizeof *d);
+ d->png_ptr = NULL;
+ d->info_ptr = d->end_ptr = NULL;
+ d->error_count = d->warning_count = 0;
+ d->program = program;
+ d->file = program;
+ d->test = init;
+}
+
+static void
+clean_display(display *d)
+{
+ png_destroy_read_struct(&d->png_ptr, &d->info_ptr, &d->end_ptr);
+
+ /* This must not happen - it might cause an app crash */
+ if (d->png_ptr != NULL || d->info_ptr != NULL || d->end_ptr != NULL)
+ {
+ fprintf(stderr, "%s(%s): png_destroy_read_struct error\n", d->file,
+ d->test);
+ exit(1);
+ }
+}
+
+PNG_FUNCTION(void, display_exit, (display *d), static PNG_NORETURN)
+{
+ ++(d->error_count);
+
+ if (d->png_ptr != NULL)
+ clean_display(d);
+
+ /* During initialization and if this is a single command line argument set
+ * exit now - there is only one test, otherwise longjmp to do the next test.
+ */
+ if (d->test == init || d->test == cmd)
+ exit(1);
+
+ longjmp(d->error_return, 1);
+}
+
+static int
+display_rc(const display *d, int strict)
+{
+ return d->error_count + (strict ? d->warning_count : 0);
+}
+
+/* libpng error and warning callbacks */
+PNG_FUNCTION(void, (PNGCBAPI error), (png_structp png_ptr, const char *message),
+ static PNG_NORETURN)
+{
+ display *d = (display*)png_get_error_ptr(png_ptr);
+
+ fprintf(stderr, "%s(%s): libpng error: %s\n", d->file, d->test, message);
+ display_exit(d);
+}
+
+static void PNGCBAPI
+warning(png_structp png_ptr, const char *message)
+{
+ display *d = (display*)png_get_error_ptr(png_ptr);
+
+ fprintf(stderr, "%s(%s): libpng warning: %s\n", d->file, d->test, message);
+ ++(d->warning_count);
+}
+
+static png_uint_32
+get_valid(display *d, png_infop info_ptr)
+{
+ png_uint_32 flags = png_get_valid(d->png_ptr, info_ptr, (png_uint_32)~0);
+
+ /* Map the text chunks back into the flags */
+ {
+ png_textp text;
+ png_uint_32 ntext = png_get_text(d->png_ptr, info_ptr, &text, NULL);
+
+ while (ntext-- > 0) switch (text[ntext].compression)
+ {
+ case -1:
+ flags |= PNG_INFO_tEXt;
+ break;
+ case 0:
+ flags |= PNG_INFO_zTXt;
+ break;
+ case 1:
+ case 2:
+ flags |= PNG_INFO_iTXt;
+ break;
+ default:
+ fprintf(stderr, "%s(%s): unknown text compression %d\n", d->file,
+ d->test, text[ntext].compression);
+ display_exit(d);
+ }
+ }
+
+ return flags;
+}
+
+#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
+static int PNGCBAPI
+read_callback(png_structp pp, png_unknown_chunkp pc)
+{
+ /* This function mimics the behavior of png_set_keep_unknown_chunks by
+ * returning '0' to keep the chunk and '1' to discard it.
+ */
+ display *d = voidcast(display*, png_get_user_chunk_ptr(pp));
+ int chunk = findb(pc->name);
+ int keep, discard;
+
+ if (chunk < 0) /* not one in our list, so not a known chunk */
+ keep = d->keep;
+
+ else
+ {
+ keep = chunk_info[chunk].keep;
+ if (keep == PNG_HANDLE_CHUNK_AS_DEFAULT)
+ {
+ /* See the comments in png.h - use the default for unknown chunks,
+ * do not keep known chunks.
+ */
+ if (chunk_info[chunk].unknown)
+ keep = d->keep;
+
+ else
+ keep = PNG_HANDLE_CHUNK_NEVER;
+ }
+ }
+
+ switch (keep)
+ {
+ default:
+ fprintf(stderr, "%s(%s): %d: unrecognized chunk option\n", d->file,
+ d->test, chunk_info[chunk].keep);
+ display_exit(d);
+
+ case PNG_HANDLE_CHUNK_AS_DEFAULT:
+ case PNG_HANDLE_CHUNK_NEVER:
+ discard = 1/*handled; discard*/;
+ break;
+
+ case PNG_HANDLE_CHUNK_IF_SAFE:
+ case PNG_HANDLE_CHUNK_ALWAYS:
+ discard = 0/*not handled; keep*/;
+ break;
+ }
+
+ /* Also store information about this chunk in the display, the relevant flag
+ * is set if the chunk is to be kept ('not handled'.)
+ */
+ if (chunk >= 0) if (!discard) /* stupidity to stop a GCC warning */
+ {
+ png_uint_32 flag = chunk_info[chunk].flag;
+
+ if (pc->location & PNG_AFTER_IDAT)
+ d->after_IDAT |= flag;
+
+ else
+ d->before_IDAT |= flag;
+ }
+
+ /* However if there is no support to store unknown chunks don't ask libpng to
+ * do it; there will be an png_error.
+ */
+# ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
+ return discard;
+# else
+ return 1; /*handled; discard*/
+# endif
+}
+#endif /* READ_USER_CHUNKS_SUPPORTED */
+
+#ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
+static png_uint_32
+get_unknown(display *d, png_infop info_ptr, int after_IDAT)
+{
+ /* Create corresponding 'unknown' flags */
+ png_uint_32 flags = 0;
+
+ UNUSED(after_IDAT)
+
+ {
+ png_unknown_chunkp unknown;
+ int num_unknown = png_get_unknown_chunks(d->png_ptr, info_ptr, &unknown);
+
+ while (--num_unknown >= 0)
+ {
+ int chunk = findb(unknown[num_unknown].name);
+
+ /* Chunks not known to pngunknown must be validated here; since they
+ * must also be unknown to libpng the 'display->keep' behavior should
+ * have been used.
+ */
+ if (chunk < 0) switch (d->keep)
+ {
+ default: /* impossible */
+ case PNG_HANDLE_CHUNK_AS_DEFAULT:
+ case PNG_HANDLE_CHUNK_NEVER:
+ fprintf(stderr, "%s(%s): %s: %s: unknown chunk saved\n",
+ d->file, d->test, d->keep ? "discard" : "default",
+ unknown[num_unknown].name);
+ ++(d->error_count);
+ break;
+
+ case PNG_HANDLE_CHUNK_IF_SAFE:
+ if (!ancillaryb(unknown[num_unknown].name))
+ {
+ fprintf(stderr,
+ "%s(%s): if-safe: %s: unknown critical chunk saved\n",
+ d->file, d->test, unknown[num_unknown].name);
+ ++(d->error_count);
+ break;
+ }
+ /* FALL THROUGH (safe) */
+ case PNG_HANDLE_CHUNK_ALWAYS:
+ break;
+ }
+
+ else
+ flags |= chunk_info[chunk].flag;
+ }
+ }
+
+ return flags;
+}
+#else
+static png_uint_32
+get_unknown(display *d, png_infop info_ptr, int after_IDAT)
+ /* Otherwise this will return the cached values set by any user callback */
+{
+ UNUSED(info_ptr);
+
+ if (after_IDAT)
+ return d->after_IDAT;
+
+ else
+ return d->before_IDAT;
+}
+
+# ifndef PNG_READ_USER_CHUNKS_SUPPORTED
+ /* The #defines above should mean this is never reached, it's just here as
+ * a check to ensure the logic is correct.
+ */
+# error No store support and no user chunk support, this will not work
+# endif
+#endif
+
+static int
+check(FILE *fp, int argc, const char **argv, png_uint_32p flags/*out*/,
+ display *d, int set_callback)
+{
+ int i, npasses, ipass;
+ png_uint_32 height;
+
+ d->keep = PNG_HANDLE_CHUNK_AS_DEFAULT;
+ d->before_IDAT = 0;
+ d->after_IDAT = 0;
+
+ /* Some of these errors are permanently fatal and cause an exit here, others
+ * are per-test and cause an error return.
+ */
+ d->png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, d, error,
+ warning);
+ if (d->png_ptr == NULL)
+ {
+ fprintf(stderr, "%s(%s): could not allocate png struct\n", d->file,
+ d->test);
+ /* Terminate here, this error is not test specific. */
+ exit(1);
+ }
+
+ d->info_ptr = png_create_info_struct(d->png_ptr);
+ d->end_ptr = png_create_info_struct(d->png_ptr);
+ if (d->info_ptr == NULL || d->end_ptr == NULL)
+ {
+ fprintf(stderr, "%s(%s): could not allocate png info\n", d->file,
+ d->test);
+ clean_display(d);
+ exit(1);
+ }
+
+ png_init_io(d->png_ptr, fp);
+
+# ifdef PNG_READ_USER_CHUNKS_SUPPORTED
+ /* This is only done if requested by the caller; it interferes with the
+ * standard store/save mechanism.
+ */
+ if (set_callback)
+ png_set_read_user_chunk_fn(d->png_ptr, d, read_callback);
+# else
+ UNUSED(set_callback)
+# endif
+
+ /* Handle each argument in turn; multiple settings are possible for the same
+ * chunk and multiple calls will occur (the last one should override all
+ * preceding ones).
+ */
+ for (i=0; i<argc; ++i)
+ {
+ const char *equals = strchr(argv[i], '=');
+
+ if (equals != NULL)
+ {
+ int chunk, option;
+
+ if (strcmp(equals+1, "default") == 0)
+ option = PNG_HANDLE_CHUNK_AS_DEFAULT;
+ else if (strcmp(equals+1, "discard") == 0)
+ option = PNG_HANDLE_CHUNK_NEVER;
+ else if (strcmp(equals+1, "if-safe") == 0)
+ option = PNG_HANDLE_CHUNK_IF_SAFE;
+ else if (strcmp(equals+1, "save") == 0)
+ option = PNG_HANDLE_CHUNK_ALWAYS;
+ else
+ {
+ fprintf(stderr, "%s(%s): %s: unrecognized chunk option\n", d->file,
+ d->test, argv[i]);
+ display_exit(d);
+ }
+
+ switch (equals - argv[i])
+ {
+ case 4: /* chunk name */
+ chunk = find(argv[i]);
+
+ if (chunk >= 0)
+ {
+ /* These #if tests have the effect of skipping the arguments
+ * if SAVE support is unavailable - we can't do a useful test
+ * in this case, so we just check the arguments! This could
+ * be improved in the future by using the read callback.
+ */
+# if PNG_LIBPNG_VER >= 10700 &&\
+ !defined(PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED)
+ if (option < PNG_HANDLE_CHUNK_IF_SAFE)
+# endif /* 1.7+ SAVE_UNKNOWN_CHUNKS */
+ {
+ png_byte name[5];
+
+ memcpy(name, chunk_info[chunk].name, 5);
+ png_set_keep_unknown_chunks(d->png_ptr, option, name, 1);
+ chunk_info[chunk].keep = option;
+ }
+ continue;
+ }
+
+ break;
+
+ case 7: /* default */
+ if (memcmp(argv[i], "default", 7) == 0)
+ {
+# if PNG_LIBPNG_VER >= 10700 &&\
+ !defined(PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED)
+ if (option < PNG_HANDLE_CHUNK_IF_SAFE)
+# endif /* 1.7+ SAVE_UNKNOWN_CHUNKS */
+ png_set_keep_unknown_chunks(d->png_ptr, option, NULL, 0);
+
+ d->keep = option;
+ continue;
+ }
+
+ break;
+
+ case 3: /* all */
+ if (memcmp(argv[i], "all", 3) == 0)
+ {
+# if PNG_LIBPNG_VER >= 10700 &&\
+ !defined(PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED)
+ if (option < PNG_HANDLE_CHUNK_IF_SAFE)
+# endif /* 1.7+ SAVE_UNKNOWN_CHUNKS */
+ png_set_keep_unknown_chunks(d->png_ptr, option, NULL, -1);
+
+ d->keep = option;
+
+ for (chunk = 0; chunk < NINFO; ++chunk)
+ if (chunk_info[chunk].all)
+ chunk_info[chunk].keep = option;
+ continue;
+ }
+
+ break;
+
+ default: /* some misplaced = */
+
+ break;
+ }
+ }
+
+ fprintf(stderr, "%s(%s): %s: unrecognized chunk argument\n", d->file,
+ d->test, argv[i]);
+ display_exit(d);
+ }
+
+ png_read_info(d->png_ptr, d->info_ptr);
+
+ switch (png_get_interlace_type(d->png_ptr, d->info_ptr))
+ {
+ case PNG_INTERLACE_NONE:
+ npasses = 1;
+ break;
+
+ case PNG_INTERLACE_ADAM7:
+ npasses = PNG_INTERLACE_ADAM7_PASSES;
+ break;
+
+ default:
+ /* Hard error because it is not test specific */
+ fprintf(stderr, "%s(%s): invalid interlace type\n", d->file, d->test);
+ clean_display(d);
+ exit(1);
+ }
+
+ /* Skip the image data, if IDAT is not being handled then don't do this
+ * because it will cause a CRC error.
+ */
+ if (chunk_info[0/*IDAT*/].keep == PNG_HANDLE_CHUNK_AS_DEFAULT)
+ {
+ png_start_read_image(d->png_ptr);
+ height = png_get_image_height(d->png_ptr, d->info_ptr);
+
+ if (npasses > 1)
+ {
+ png_uint_32 width = png_get_image_width(d->png_ptr, d->info_ptr);
+
+ for (ipass=0; ipass<npasses; ++ipass)
+ {
+ png_uint_32 wPass = PNG_PASS_COLS(width, ipass);
+
+ if (wPass > 0)
+ {
+ png_uint_32 y;
+
+ for (y=0; y<height; ++y) if (PNG_ROW_IN_INTERLACE_PASS(y, ipass))
+ png_read_row(d->png_ptr, NULL, NULL);
+ }
+ }
+ } /* interlaced */
+
+ else /* not interlaced */
+ {
+ png_uint_32 y;
+
+ for (y=0; y<height; ++y)
+ png_read_row(d->png_ptr, NULL, NULL);
+ }
+ }
+
+ png_read_end(d->png_ptr, d->end_ptr);
+
+ flags[0] = get_valid(d, d->info_ptr);
+ flags[1] = get_unknown(d, d->info_ptr, 0/*before IDAT*/);
+
+ /* Only png_read_png sets PNG_INFO_IDAT! */
+ flags[chunk_info[0/*IDAT*/].keep != PNG_HANDLE_CHUNK_AS_DEFAULT] |=
+ PNG_INFO_IDAT;
+
+ flags[2] = get_valid(d, d->end_ptr);
+ flags[3] = get_unknown(d, d->end_ptr, 1/*after IDAT*/);
+
+ clean_display(d);
+
+ return d->keep;
+}
+
+static void
+check_error(display *d, png_uint_32 flags, const char *message)
+{
+ while (flags)
+ {
+ png_uint_32 flag = flags & -(png_int_32)flags;
+ int i = find_by_flag(flag);
+
+ fprintf(stderr, "%s(%s): chunk %s: %s\n", d->file, d->test,
+ chunk_info[i].name, message);
+ ++(d->error_count);
+
+ flags &= ~flag;
+ }
+}
+
+static void
+check_handling(display *d, int def, png_uint_32 chunks, png_uint_32 known,
+ png_uint_32 unknown, const char *position, int set_callback)
+{
+ while (chunks)
+ {
+ png_uint_32 flag = chunks & -(png_int_32)chunks;
+ int i = find_by_flag(flag);
+ int keep = chunk_info[i].keep;
+ const char *type;
+ const char *errorx = NULL;
+
+ if (chunk_info[i].unknown)
+ {
+ if (keep == PNG_HANDLE_CHUNK_AS_DEFAULT)
+ {
+ type = "UNKNOWN (default)";
+ keep = def;
+ }
+
+ else
+ type = "UNKNOWN (specified)";
+
+ if (flag & known)
+ errorx = "chunk processed";
+
+ else switch (keep)
+ {
+ case PNG_HANDLE_CHUNK_AS_DEFAULT:
+ if (flag & unknown)
+ errorx = "DEFAULT: unknown chunk saved";
+ break;
+
+ case PNG_HANDLE_CHUNK_NEVER:
+ if (flag & unknown)
+ errorx = "DISCARD: unknown chunk saved";
+ break;
+
+ case PNG_HANDLE_CHUNK_IF_SAFE:
+ if (ancillary(chunk_info[i].name))
+ {
+ if (!(flag & unknown))
+ errorx = "IF-SAFE: unknown ancillary chunk lost";
+ }
+
+ else if (flag & unknown)
+ errorx = "IF-SAFE: unknown critical chunk saved";
+ break;
+
+ case PNG_HANDLE_CHUNK_ALWAYS:
+ if (!(flag & unknown))
+ errorx = "SAVE: unknown chunk lost";
+ break;
+
+ default:
+ errorx = "internal error: bad keep";
+ break;
+ }
+ } /* unknown chunk */
+
+ else /* known chunk */
+ {
+ type = "KNOWN";
+
+ if (flag & known)
+ {
+ /* chunk was processed, it won't have been saved because that is
+ * caught below when checking for inconsistent processing.
+ */
+ if (keep != PNG_HANDLE_CHUNK_AS_DEFAULT)
+ errorx = "!DEFAULT: known chunk processed";
+ }
+
+ else /* not processed */ switch (keep)
+ {
+ case PNG_HANDLE_CHUNK_AS_DEFAULT:
+ errorx = "DEFAULT: known chunk not processed";
+ break;
+
+ case PNG_HANDLE_CHUNK_NEVER:
+ if (flag & unknown)
+ errorx = "DISCARD: known chunk saved";
+ break;
+
+ case PNG_HANDLE_CHUNK_IF_SAFE:
+ if (ancillary(chunk_info[i].name))
+ {
+ if (!(flag & unknown))
+ errorx = "IF-SAFE: known ancillary chunk lost";
+ }
+
+ else if (flag & unknown)
+ errorx = "IF-SAFE: known critical chunk saved";
+ break;
+
+ case PNG_HANDLE_CHUNK_ALWAYS:
+ if (!(flag & unknown))
+ errorx = "SAVE: known chunk lost";
+ break;
+
+ default:
+ errorx = "internal error: bad keep (2)";
+ break;
+ }
+ }
+
+ if (errorx != NULL)
+ {
+ ++(d->error_count);
+ fprintf(stderr, "%s(%s%s): %s %s %s: %s\n", d->file, d->test,
+ set_callback ? ",callback" : "",
+ type, chunk_info[i].name, position, errorx);
+ }
+
+ chunks &= ~flag;
+ }
+}
+
+static void
+perform_one_test(FILE *fp, int argc, const char **argv,
+ png_uint_32 *default_flags, display *d, int set_callback)
+{
+ int def;
+ png_uint_32 flags[2][4];
+
+ rewind(fp);
+ clear_keep();
+ memcpy(flags[0], default_flags, sizeof flags[0]);
+
+ def = check(fp, argc, argv, flags[1], d, set_callback);
+
+ /* Chunks should either be known or unknown, never both and this should apply
+ * whether the chunk is before or after the IDAT (actually, the app can
+ * probably change this by swapping the handling after the image, but this
+ * test does not do that.)
+ */
+ check_error(d, (flags[0][0]|flags[0][2]) & (flags[0][1]|flags[0][3]),
+ "chunk handled inconsistently in count tests");
+ check_error(d, (flags[1][0]|flags[1][2]) & (flags[1][1]|flags[1][3]),
+ "chunk handled inconsistently in option tests");
+
+ /* Now find out what happened to each chunk before and after the IDAT and
+ * determine if the behavior was correct. First some basic sanity checks,
+ * any known chunk should be known in the original count, any unknown chunk
+ * should be either known or unknown in the original.
+ */
+ {
+ png_uint_32 test;
+
+ test = flags[1][0] & ~flags[0][0];
+ check_error(d, test, "new known chunk before IDAT");
+ test = flags[1][1] & ~(flags[0][0] | flags[0][1]);
+ check_error(d, test, "new unknown chunk before IDAT");
+ test = flags[1][2] & ~flags[0][2];
+ check_error(d, test, "new known chunk after IDAT");
+ test = flags[1][3] & ~(flags[0][2] | flags[0][3]);
+ check_error(d, test, "new unknown chunk after IDAT");
+ }
+
+ /* Now each chunk in the original list should have been handled according to
+ * the options set for that chunk, regardless of whether libpng knows about
+ * it or not.
+ */
+ check_handling(d, def, flags[0][0] | flags[0][1], flags[1][0], flags[1][1],
+ "before IDAT", set_callback);
+ check_handling(d, def, flags[0][2] | flags[0][3], flags[1][2], flags[1][3],
+ "after IDAT", set_callback);
+}
+
+static void
+perform_one_test_safe(FILE *fp, int argc, const char **argv,
+ png_uint_32 *default_flags, display *d, const char *test)
+{
+ if (setjmp(d->error_return) == 0)
+ {
+ d->test = test; /* allow use of d->error_return */
+# ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
+ perform_one_test(fp, argc, argv, default_flags, d, 0);
+# endif
+# ifdef PNG_READ_USER_CHUNKS_SUPPORTED
+ perform_one_test(fp, argc, argv, default_flags, d, 1);
+# endif
+ d->test = init; /* prevent use of d->error_return */
+ }
+}
+
+static const char *standard_tests[] =
+{
+ "discard", "default=discard", 0,
+ "save", "default=save", 0,
+ "if-safe", "default=if-safe", 0,
+ "vpAg", "vpAg=if-safe", 0,
+ "sTER", "sTER=if-safe", 0,
+ "IDAT", "default=discard", "IDAT=save", 0,
+ "sAPI", "bKGD=save", "cHRM=save", "gAMA=save", "all=discard", "iCCP=save",
+ "sBIT=save", "sRGB=save", 0,
+ 0/*end*/
+};
+
+static PNG_NORETURN void
+usage(const char *program, const char *reason)
+{
+ fprintf(stderr, "pngunknown: %s: usage:\n %s [--strict] "
+ "--default|{(CHNK|default|all)=(default|discard|if-safe|save)} "
+ "testfile.png\n", reason, program);
+ exit(99);
+}
+
+int
+main(int argc, const char **argv)
+{
+ FILE *fp;
+ png_uint_32 default_flags[4/*valid,unknown{before,after}*/];
+ int strict = 0, default_tests = 0;
+ const char *count_argv = "default=save";
+ const char *touch_file = NULL;
+ display d;
+
+ init_display(&d, argv[0]);
+
+ while (++argv, --argc > 0)
+ {
+ if (strcmp(*argv, "--strict") == 0)
+ strict = 1;
+
+ else if (strcmp(*argv, "--default") == 0)
+ default_tests = 1;
+
+ else if (strcmp(*argv, "--touch") == 0)
+ {
+ if (argc > 1)
+ touch_file = *++argv, --argc;
+
+ else
+ usage(d.program, "--touch: missing file name");
+ }
+
+ else
+ break;
+ }
+
+ /* A file name is required, but there should be no other arguments if
+ * --default was specified.
+ */
+ if (argc <= 0)
+ usage(d.program, "missing test file");
+
+ /* GCC BUG: if (default_tests && argc != 1) triggers some weird GCC argc
+ * optimization which causes warnings with -Wstrict-overflow!
+ */
+ else if (default_tests) if (argc != 1)
+ usage(d.program, "extra arguments");
+
+ /* The name of the test file is the last argument; remove it. */
+ d.file = argv[--argc];
+
+ fp = fopen(d.file, "rb");
+ if (fp == NULL)
+ {
+ perror(d.file);
+ exit(99);
+ }
+
+ /* First find all the chunks, known and unknown, in the test file, a failure
+ * here aborts the whole test.
+ *
+ * If 'save' is supported then the normal saving method should happen,
+ * otherwise if 'read' is supported then the read callback will do the
+ * same thing. If both are supported the 'read' callback won't be
+ * instantiated by default. If 'save' is *not* supported then a user
+ * callback is required even though we can call png_get_unknown_chunks.
+ */
+ if (check(fp, 1, &count_argv, default_flags, &d,
+# ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
+ 0
+# else
+ 1
+# endif
+ ) != PNG_HANDLE_CHUNK_ALWAYS)
+ {
+ fprintf(stderr, "%s: %s: internal error\n", d.program, d.file);
+ exit(99);
+ }
+
+ /* Now find what the various supplied options cause to change: */
+ if (!default_tests)
+ {
+ d.test = cmd; /* acts as a flag to say exit, do not longjmp */
+# ifdef PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED
+ perform_one_test(fp, argc, argv, default_flags, &d, 0);
+# endif
+# ifdef PNG_READ_USER_CHUNKS_SUPPORTED
+ perform_one_test(fp, argc, argv, default_flags, &d, 1);
+# endif
+ d.test = init;
+ }
+
+ else
+ {
+ const char **test = standard_tests;
+
+ /* Set the exit_test pointer here so we can continue after a libpng error.
+ * NOTE: this leaks memory because the png_struct data from the failing
+ * test is never freed.
+ */
+ while (*test)
+ {
+ const char *this_test = *test++;
+ const char **next = test;
+ int count = display_rc(&d, strict), new_count;
+ const char *result;
+ int arg_count = 0;
+
+ while (*next) ++next, ++arg_count;
+
+ perform_one_test_safe(fp, arg_count, test, default_flags, &d,
+ this_test);
+
+ new_count = display_rc(&d, strict);
+
+ if (new_count == count)
+ result = "PASS";
+
+ else
+ result = "FAIL";
+
+ printf("%s: %s %s\n", result, d.program, this_test);
+
+ test = next+1;
+ }
+ }
+
+ fclose(fp);
+
+ if (display_rc(&d, strict) == 0)
+ {
+ /* Success, touch the success file if appropriate */
+ if (touch_file != NULL)
+ {
+ FILE *fsuccess = fopen(touch_file, "wt");
+
+ if (fsuccess != NULL)
+ {
+ int err = 0;
+ fprintf(fsuccess, "PNG unknown tests succeeded\n");
+ fflush(fsuccess);
+ err = ferror(fsuccess);
+
+ if (fclose(fsuccess) || err)
+ {
+ fprintf(stderr, "%s: write failed\n", touch_file);
+ exit(99);
+ }
+ }
+
+ else
+ {
+ fprintf(stderr, "%s: open failed\n", touch_file);
+ exit(99);
+ }
+ }
+
+ return 0;
+ }
+
+ return 1;
+}
+
+#else /* !(READ_USER_CHUNKS || SAVE_UNKNOWN_CHUNKS) */
+int
+main(void)
+{
+ fprintf(stderr,
+ " test ignored: no support to find out about unknown chunks\n");
+ /* So the test is skipped: */
+ return 77;
+}
+#endif /* READ_USER_CHUNKS || SAVE_UNKNOWN_CHUNKS */
+
+#else /* !(SET_UNKNOWN_CHUNKS && READ) */
+int
+main(void)
+{
+ fprintf(stderr,
+ " test ignored: no support to modify unknown chunk handling\n");
+ /* So the test is skipped: */
+ return 77;
+}
+#endif /* SET_UNKNOWN_CHUNKS && READ*/
diff --git a/libpng/contrib/libtests/pngvalid.c b/libpng/contrib/libtests/pngvalid.c
new file mode 100644
index 0000000..bdd3c91
--- /dev/null
+++ b/libpng/contrib/libtests/pngvalid.c
@@ -0,0 +1,11746 @@
+
+/* pngvalid.c - validate libpng by constructing then reading png files.
+ *
+ * Last changed in libpng 1.5.25 [December 3, 2015]
+ * Copyright (c) 2014-2015 Glenn Randers-Pehrson
+ * Written by John Cunningham Bowler
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * NOTES:
+ * This is a C program that is intended to be linked against libpng. It
+ * generates bitmaps internally, stores them as PNG files (using the
+ * sequential write code) then reads them back (using the sequential
+ * read code) and validates that the result has the correct data.
+ *
+ * The program can be modified and extended to test the correctness of
+ * transformations performed by libpng.
+ */
+
+#define _POSIX_SOURCE 1
+#define _ISOC99_SOURCE 1 /* For floating point */
+#define _GNU_SOURCE 1 /* For the floating point exception extension */
+
+#include <signal.h>
+#include <stdio.h>
+
+#if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H)
+# include <config.h>
+#endif
+
+#ifdef HAVE_FEENABLEEXCEPT /* from config.h, if included */
+# include <fenv.h>
+#endif
+
+#ifndef FE_DIVBYZERO
+# define FE_DIVBYZERO 0
+#endif
+#ifndef FE_INVALID
+# define FE_INVALID 0
+#endif
+#ifndef FE_OVERFLOW
+# define FE_OVERFLOW 0
+#endif
+
+/* Define the following to use this test against your installed libpng, rather
+ * than the one being built here:
+ */
+#ifdef PNG_FREESTANDING_TESTS
+# include <png.h>
+#else
+# include "../../png.h"
+#endif
+
+#ifdef PNG_ZLIB_HEADER
+# include PNG_ZLIB_HEADER
+#else
+# include <zlib.h> /* For crc32 */
+#endif
+
+/* 1.6.1 added support for the configure test harness, which uses 77 to indicate
+ * a skipped test, in earlier versions we need to succeed on a skipped test, so:
+ */
+#if PNG_LIBPNG_VER < 10601
+# define SKIP 0
+#else
+# define SKIP 77
+#endif
+
+/* pngvalid requires write support and one of the fixed or floating point APIs.
+ */
+#if defined(PNG_WRITE_SUPPORTED) &&\
+ (defined(PNG_FIXED_POINT_SUPPORTED) || defined(PNG_FLOATING_POINT_SUPPORTED))
+
+#if PNG_LIBPNG_VER < 10500
+/* This deliberately lacks the const. */
+typedef png_byte *png_const_bytep;
+
+/* This is copied from 1.5.1 png.h: */
+#define PNG_INTERLACE_ADAM7_PASSES 7
+#define PNG_PASS_START_ROW(pass) (((1U&~(pass))<<(3-((pass)>>1)))&7)
+#define PNG_PASS_START_COL(pass) (((1U& (pass))<<(3-(((pass)+1)>>1)))&7)
+#define PNG_PASS_ROW_SHIFT(pass) ((pass)>2?(8-(pass))>>1:3)
+#define PNG_PASS_COL_SHIFT(pass) ((pass)>1?(7-(pass))>>1:3)
+#define PNG_PASS_ROWS(height, pass) (((height)+(((1<<PNG_PASS_ROW_SHIFT(pass))\
+ -1)-PNG_PASS_START_ROW(pass)))>>PNG_PASS_ROW_SHIFT(pass))
+#define PNG_PASS_COLS(width, pass) (((width)+(((1<<PNG_PASS_COL_SHIFT(pass))\
+ -1)-PNG_PASS_START_COL(pass)))>>PNG_PASS_COL_SHIFT(pass))
+#define PNG_ROW_FROM_PASS_ROW(yIn, pass) \
+ (((yIn)<<PNG_PASS_ROW_SHIFT(pass))+PNG_PASS_START_ROW(pass))
+#define PNG_COL_FROM_PASS_COL(xIn, pass) \
+ (((xIn)<<PNG_PASS_COL_SHIFT(pass))+PNG_PASS_START_COL(pass))
+#define PNG_PASS_MASK(pass,off) ( \
+ ((0x110145AFU>>(((7-(off))-(pass))<<2)) & 0xFU) | \
+ ((0x01145AF0U>>(((7-(off))-(pass))<<2)) & 0xF0U))
+#define PNG_ROW_IN_INTERLACE_PASS(y, pass) \
+ ((PNG_PASS_MASK(pass,0) >> ((y)&7)) & 1)
+#define PNG_COL_IN_INTERLACE_PASS(x, pass) \
+ ((PNG_PASS_MASK(pass,1) >> ((x)&7)) & 1)
+
+/* These are needed too for the default build: */
+#define PNG_WRITE_16BIT_SUPPORTED
+#define PNG_READ_16BIT_SUPPORTED
+
+/* This comes from pnglibconf.h afer 1.5: */
+#define PNG_FP_1 100000
+#define PNG_GAMMA_THRESHOLD_FIXED\
+ ((png_fixed_point)(PNG_GAMMA_THRESHOLD * PNG_FP_1))
+#endif
+
+#if PNG_LIBPNG_VER < 10600
+ /* 1.6.0 constifies many APIs, the following exists to allow pngvalid to be
+ * compiled against earlier versions.
+ */
+# define png_const_structp png_structp
+#endif
+
+#include <float.h> /* For floating point constants */
+#include <stdlib.h> /* For malloc */
+#include <string.h> /* For memcpy, memset */
+#include <math.h> /* For floor */
+
+/* Unused formal parameter errors are removed using the following macro which is
+ * expected to have no bad effects on performance.
+ */
+#ifndef UNUSED
+# if defined(__GNUC__) || defined(_MSC_VER)
+# define UNUSED(param) (void)param;
+# else
+# define UNUSED(param)
+# endif
+#endif
+
+/***************************** EXCEPTION HANDLING *****************************/
+#ifdef PNG_FREESTANDING_TESTS
+# include <cexcept.h>
+#else
+# include "../visupng/cexcept.h"
+#endif
+
+#ifdef __cplusplus
+# define this not_the_cpp_this
+# define new not_the_cpp_new
+# define voidcast(type, value) static_cast<type>(value)
+#else
+# define voidcast(type, value) (value)
+#endif /* __cplusplus */
+
+struct png_store;
+define_exception_type(struct png_store*);
+
+/* The following are macros to reduce typing everywhere where the well known
+ * name 'the_exception_context' must be defined.
+ */
+#define anon_context(ps) struct exception_context *the_exception_context = \
+ &(ps)->exception_context
+#define context(ps,fault) anon_context(ps); png_store *fault
+
+/* This macro returns the number of elements in an array as an (unsigned int),
+ * it is necessary to avoid the inability of certain versions of GCC to use
+ * the value of a compile-time constant when performing range checks. It must
+ * be passed an array name.
+ */
+#define ARRAY_SIZE(a) ((unsigned int)((sizeof (a))/(sizeof (a)[0])))
+
+/* GCC BUG 66447 (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66447) requires
+ * some broken GCC versions to be fixed up to avoid invalid whining about auto
+ * variables that are *not* changed within the scope of a setjmp being changed.
+ *
+ * Feel free to extend the list of broken versions.
+ */
+#define is_gnu(major,minor)\
+ (defined __GNUC__) && __GNUC__ == (major) && __GNUC_MINOR__ == (minor)
+#define is_gnu_patch(major,minor,patch)\
+ is_gnu(major,minor) && __GNUC_PATCHLEVEL__ == 0
+/* For the moment just do it always; all versions of GCC seem to be broken: */
+#ifdef __GNUC__
+ const void * volatile make_volatile_for_gnu;
+# define gnu_volatile(x) make_volatile_for_gnu = &x;
+#else /* !GNUC broken versions */
+# define gnu_volatile(x)
+#endif /* !GNUC broken versions */
+
+/******************************* UTILITIES ************************************/
+/* Error handling is particularly problematic in production code - error
+ * handlers often themselves have bugs which lead to programs that detect
+ * minor errors crashing. The following functions deal with one very
+ * common class of errors in error handlers - attempting to format error or
+ * warning messages into buffers that are too small.
+ */
+static size_t safecat(char *buffer, size_t bufsize, size_t pos,
+ const char *cat)
+{
+ while (pos < bufsize && cat != NULL && *cat != 0)
+ buffer[pos++] = *cat++;
+
+ if (pos >= bufsize)
+ pos = bufsize-1;
+
+ buffer[pos] = 0;
+ return pos;
+}
+
+static size_t safecatn(char *buffer, size_t bufsize, size_t pos, int n)
+{
+ char number[64];
+ sprintf(number, "%d", n);
+ return safecat(buffer, bufsize, pos, number);
+}
+
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
+static size_t safecatd(char *buffer, size_t bufsize, size_t pos, double d,
+ int precision)
+{
+ char number[64];
+ sprintf(number, "%.*f", precision, d);
+ return safecat(buffer, bufsize, pos, number);
+}
+#endif
+
+static const char invalid[] = "invalid";
+static const char sep[] = ": ";
+
+static const char *colour_types[8] =
+{
+ "grayscale", invalid, "truecolour", "indexed-colour",
+ "grayscale with alpha", invalid, "truecolour with alpha", invalid
+};
+
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
+/* Convert a double precision value to fixed point. */
+static png_fixed_point
+fix(double d)
+{
+ d = floor(d * PNG_FP_1 + .5);
+ return (png_fixed_point)d;
+}
+#endif /* PNG_READ_SUPPORTED */
+
+/* Generate random bytes. This uses a boring repeatable algorithm and it
+ * is implemented here so that it gives the same set of numbers on every
+ * architecture. It's a linear congruential generator (Knuth or Sedgewick
+ * "Algorithms") but it comes from the 'feedback taps' table in Horowitz and
+ * Hill, "The Art of Electronics" (Pseudo-Random Bit Sequences and Noise
+ * Generation.)
+ */
+static void
+make_random_bytes(png_uint_32* seed, void* pv, size_t size)
+{
+ png_uint_32 u0 = seed[0], u1 = seed[1];
+ png_bytep bytes = voidcast(png_bytep, pv);
+
+ /* There are thirty three bits, the next bit in the sequence is bit-33 XOR
+ * bit-20. The top 1 bit is in u1, the bottom 32 are in u0.
+ */
+ size_t i;
+ for (i=0; i<size; ++i)
+ {
+ /* First generate 8 new bits then shift them in at the end. */
+ png_uint_32 u = ((u0 >> (20-8)) ^ ((u1 << 7) | (u0 >> (32-7)))) & 0xff;
+ u1 <<= 8;
+ u1 |= u0 >> 24;
+ u0 <<= 8;
+ u0 |= u;
+ *bytes++ = (png_byte)u;
+ }
+
+ seed[0] = u0;
+ seed[1] = u1;
+}
+
+static void
+make_four_random_bytes(png_uint_32* seed, png_bytep bytes)
+{
+ make_random_bytes(seed, bytes, 4);
+}
+
+#if defined PNG_READ_SUPPORTED || defined PNG_WRITE_tRNS_SUPPORTED
+static void
+randomize(void *pv, size_t size)
+{
+ static png_uint_32 random_seed[2] = {0x56789abc, 0xd};
+ make_random_bytes(random_seed, pv, size);
+}
+
+#define RANDOMIZE(this) randomize(&(this), sizeof (this))
+#endif /* READ || WRITE_tRNS */
+
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
+static unsigned int
+random_mod(unsigned int max)
+{
+ unsigned int x;
+
+ RANDOMIZE(x);
+
+ return x % max; /* 0 .. max-1 */
+}
+
+#if (defined PNG_READ_RGB_TO_GRAY_SUPPORTED) ||\
+ (defined PNG_READ_FILLER_SUPPORTED)
+static int
+random_choice(void)
+{
+ unsigned char x;
+
+ RANDOMIZE(x);
+
+ return x & 1;
+}
+#endif
+#endif /* PNG_READ_SUPPORTED */
+
+/* A numeric ID based on PNG file characteristics. The 'do_interlace' field
+ * simply records whether pngvalid did the interlace itself or whether it
+ * was done by libpng. Width and height must be less than 256. 'palette' is an
+ * index of the palette to use for formats with a palette otherwise a boolean
+ * indicating if a tRNS chunk was generated.
+ */
+#define FILEID(col, depth, palette, interlace, width, height, do_interlace) \
+ ((png_uint_32)((col) + ((depth)<<3) + ((palette)<<8) + ((interlace)<<13) + \
+ (((do_interlace)!=0)<<15) + ((width)<<16) + ((height)<<24)))
+
+#define COL_FROM_ID(id) ((png_byte)((id)& 0x7U))
+#define DEPTH_FROM_ID(id) ((png_byte)(((id) >> 3) & 0x1fU))
+#define PALETTE_FROM_ID(id) (((id) >> 8) & 0x1f)
+#define INTERLACE_FROM_ID(id) ((png_byte)(((id) >> 13) & 0x3))
+#define DO_INTERLACE_FROM_ID(id) ((int)(((id)>>15) & 1))
+#define WIDTH_FROM_ID(id) (((id)>>16) & 0xff)
+#define HEIGHT_FROM_ID(id) (((id)>>24) & 0xff)
+
+/* Utility to construct a standard name for a standard image. */
+static size_t
+standard_name(char *buffer, size_t bufsize, size_t pos, png_byte colour_type,
+ int bit_depth, unsigned int npalette, int interlace_type,
+ png_uint_32 w, png_uint_32 h, int do_interlace)
+{
+ pos = safecat(buffer, bufsize, pos, colour_types[colour_type]);
+ if (colour_type == 3) /* must have a palette */
+ {
+ pos = safecat(buffer, bufsize, pos, "[");
+ pos = safecatn(buffer, bufsize, pos, npalette);
+ pos = safecat(buffer, bufsize, pos, "]");
+ }
+
+ else if (npalette != 0)
+ pos = safecat(buffer, bufsize, pos, "+tRNS");
+
+ pos = safecat(buffer, bufsize, pos, " ");
+ pos = safecatn(buffer, bufsize, pos, bit_depth);
+ pos = safecat(buffer, bufsize, pos, " bit");
+
+ if (interlace_type != PNG_INTERLACE_NONE)
+ {
+ pos = safecat(buffer, bufsize, pos, " interlaced");
+ if (do_interlace)
+ pos = safecat(buffer, bufsize, pos, "(pngvalid)");
+ else
+ pos = safecat(buffer, bufsize, pos, "(libpng)");
+ }
+
+ if (w > 0 || h > 0)
+ {
+ pos = safecat(buffer, bufsize, pos, " ");
+ pos = safecatn(buffer, bufsize, pos, w);
+ pos = safecat(buffer, bufsize, pos, "x");
+ pos = safecatn(buffer, bufsize, pos, h);
+ }
+
+ return pos;
+}
+
+static size_t
+standard_name_from_id(char *buffer, size_t bufsize, size_t pos, png_uint_32 id)
+{
+ return standard_name(buffer, bufsize, pos, COL_FROM_ID(id),
+ DEPTH_FROM_ID(id), PALETTE_FROM_ID(id), INTERLACE_FROM_ID(id),
+ WIDTH_FROM_ID(id), HEIGHT_FROM_ID(id), DO_INTERLACE_FROM_ID(id));
+}
+
+/* Convenience API and defines to list valid formats. Note that 16 bit read and
+ * write support is required to do 16 bit read tests (we must be able to make a
+ * 16 bit image to test!)
+ */
+#ifdef PNG_WRITE_16BIT_SUPPORTED
+# define WRITE_BDHI 4
+# ifdef PNG_READ_16BIT_SUPPORTED
+# define READ_BDHI 4
+# define DO_16BIT
+# endif
+#else
+# define WRITE_BDHI 3
+#endif
+#ifndef DO_16BIT
+# define READ_BDHI 3
+#endif
+
+/* The following defines the number of different palettes to generate for
+ * each log bit depth of a colour type 3 standard image.
+ */
+#define PALETTE_COUNT(bit_depth) ((bit_depth) > 4 ? 1U : 16U)
+
+static int
+next_format(png_bytep colour_type, png_bytep bit_depth,
+ unsigned int* palette_number, int low_depth_gray, int tRNS)
+{
+ if (*bit_depth == 0)
+ {
+ *colour_type = 0;
+ if (low_depth_gray)
+ *bit_depth = 1;
+ else
+ *bit_depth = 8;
+ *palette_number = 0;
+ return 1;
+ }
+
+ if (*colour_type < 4/*no alpha channel*/)
+ {
+ /* Add multiple palettes for colour type 3, one image with tRNS
+ * and one without for other non-alpha formats:
+ */
+ unsigned int pn = ++*palette_number;
+ png_byte ct = *colour_type;
+
+ if (((ct == 0/*GRAY*/ || ct/*RGB*/ == 2) && tRNS && pn < 2) ||
+ (ct == 3/*PALETTE*/ && pn < PALETTE_COUNT(*bit_depth)))
+ return 1;
+
+ /* No: next bit depth */
+ *palette_number = 0;
+ }
+
+ *bit_depth = (png_byte)(*bit_depth << 1);
+
+ /* Palette images are restricted to 8 bit depth */
+ if (*bit_depth <= 8
+#ifdef DO_16BIT
+ || (*colour_type != 3 && *bit_depth <= 16)
+#endif
+ )
+ return 1;
+
+ /* Move to the next color type, or return 0 at the end. */
+ switch (*colour_type)
+ {
+ case 0:
+ *colour_type = 2;
+ *bit_depth = 8;
+ return 1;
+
+ case 2:
+ *colour_type = 3;
+ *bit_depth = 1;
+ return 1;
+
+ case 3:
+ *colour_type = 4;
+ *bit_depth = 8;
+ return 1;
+
+ case 4:
+ *colour_type = 6;
+ *bit_depth = 8;
+ return 1;
+
+ default:
+ return 0;
+ }
+}
+
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
+static unsigned int
+sample(png_const_bytep row, png_byte colour_type, png_byte bit_depth,
+ png_uint_32 x, unsigned int sample_index, int swap16, int littleendian)
+{
+ png_uint_32 bit_index, result;
+
+ /* Find a sample index for the desired sample: */
+ x *= bit_depth;
+ bit_index = x;
+
+ if ((colour_type & 1) == 0) /* !palette */
+ {
+ if (colour_type & 2)
+ bit_index *= 3;
+
+ if (colour_type & 4)
+ bit_index += x; /* Alpha channel */
+
+ /* Multiple channels; select one: */
+ if (colour_type & (2+4))
+ bit_index += sample_index * bit_depth;
+ }
+
+ /* Return the sample from the row as an integer. */
+ row += bit_index >> 3;
+ result = *row;
+
+ if (bit_depth == 8)
+ return result;
+
+ else if (bit_depth > 8)
+ {
+ if (swap16)
+ return (*++row << 8) + result;
+ else
+ return (result << 8) + *++row;
+ }
+
+ /* Less than 8 bits per sample. By default PNG has the big end of
+ * the egg on the left of the screen, but if littleendian is set
+ * then the big end is on the right.
+ */
+ bit_index &= 7;
+
+ if (!littleendian)
+ bit_index = 8-bit_index-bit_depth;
+
+ return (result >> bit_index) & ((1U<<bit_depth)-1);
+}
+#endif /* PNG_READ_TRANSFORMS_SUPPORTED */
+
+/* Copy a single pixel, of a given size, from one buffer to another -
+ * while this is basically bit addressed there is an implicit assumption
+ * that pixels 8 or more bits in size are byte aligned and that pixels
+ * do not otherwise cross byte boundaries. (This is, so far as I know,
+ * universally true in bitmap computer graphics. [JCB 20101212])
+ *
+ * NOTE: The to and from buffers may be the same.
+ */
+static void
+pixel_copy(png_bytep toBuffer, png_uint_32 toIndex,
+ png_const_bytep fromBuffer, png_uint_32 fromIndex, unsigned int pixelSize,
+ int littleendian)
+{
+ /* Assume we can multiply by 'size' without overflow because we are
+ * just working in a single buffer.
+ */
+ toIndex *= pixelSize;
+ fromIndex *= pixelSize;
+ if (pixelSize < 8) /* Sub-byte */
+ {
+ /* Mask to select the location of the copied pixel: */
+ unsigned int destMask = ((1U<<pixelSize)-1) <<
+ (littleendian ? toIndex&7 : 8-pixelSize-(toIndex&7));
+ /* The following read the entire pixels and clears the extra: */
+ unsigned int destByte = toBuffer[toIndex >> 3] & ~destMask;
+ unsigned int sourceByte = fromBuffer[fromIndex >> 3];
+
+ /* Don't rely on << or >> supporting '0' here, just in case: */
+ fromIndex &= 7;
+ if (littleendian)
+ {
+ if (fromIndex > 0) sourceByte >>= fromIndex;
+ if ((toIndex & 7) > 0) sourceByte <<= toIndex & 7;
+ }
+
+ else
+ {
+ if (fromIndex > 0) sourceByte <<= fromIndex;
+ if ((toIndex & 7) > 0) sourceByte >>= toIndex & 7;
+ }
+
+ toBuffer[toIndex >> 3] = (png_byte)(destByte | (sourceByte & destMask));
+ }
+ else /* One or more bytes */
+ memmove(toBuffer+(toIndex>>3), fromBuffer+(fromIndex>>3), pixelSize>>3);
+}
+
+#ifdef PNG_READ_SUPPORTED
+/* Copy a complete row of pixels, taking into account potential partial
+ * bytes at the end.
+ */
+static void
+row_copy(png_bytep toBuffer, png_const_bytep fromBuffer, unsigned int bitWidth,
+ int littleendian)
+{
+ memcpy(toBuffer, fromBuffer, bitWidth >> 3);
+
+ if ((bitWidth & 7) != 0)
+ {
+ unsigned int mask;
+
+ toBuffer += bitWidth >> 3;
+ fromBuffer += bitWidth >> 3;
+ if (littleendian)
+ mask = 0xff << (bitWidth & 7);
+ else
+ mask = 0xff >> (bitWidth & 7);
+ *toBuffer = (png_byte)((*toBuffer & mask) | (*fromBuffer & ~mask));
+ }
+}
+
+/* Compare pixels - they are assumed to start at the first byte in the
+ * given buffers.
+ */
+static int
+pixel_cmp(png_const_bytep pa, png_const_bytep pb, png_uint_32 bit_width)
+{
+#if PNG_LIBPNG_VER < 10506
+ if (memcmp(pa, pb, bit_width>>3) == 0)
+ {
+ png_uint_32 p;
+
+ if ((bit_width & 7) == 0) return 0;
+
+ /* Ok, any differences? */
+ p = pa[bit_width >> 3];
+ p ^= pb[bit_width >> 3];
+
+ if (p == 0) return 0;
+
+ /* There are, but they may not be significant, remove the bits
+ * after the end (the low order bits in PNG.)
+ */
+ bit_width &= 7;
+ p >>= 8-bit_width;
+
+ if (p == 0) return 0;
+ }
+#else
+ /* From libpng-1.5.6 the overwrite should be fixed, so compare the trailing
+ * bits too:
+ */
+ if (memcmp(pa, pb, (bit_width+7)>>3) == 0)
+ return 0;
+#endif
+
+ /* Return the index of the changed byte. */
+ {
+ png_uint_32 where = 0;
+
+ while (pa[where] == pb[where]) ++where;
+ return 1+where;
+ }
+}
+#endif /* PNG_READ_SUPPORTED */
+
+/*************************** BASIC PNG FILE WRITING ***************************/
+/* A png_store takes data from the sequential writer or provides data
+ * to the sequential reader. It can also store the result of a PNG
+ * write for later retrieval.
+ */
+#define STORE_BUFFER_SIZE 500 /* arbitrary */
+typedef struct png_store_buffer
+{
+ struct png_store_buffer* prev; /* NOTE: stored in reverse order */
+ png_byte buffer[STORE_BUFFER_SIZE];
+} png_store_buffer;
+
+#define FILE_NAME_SIZE 64
+
+typedef struct store_palette_entry /* record of a single palette entry */
+{
+ png_byte red;
+ png_byte green;
+ png_byte blue;
+ png_byte alpha;
+} store_palette_entry, store_palette[256];
+
+typedef struct png_store_file
+{
+ struct png_store_file* next; /* as many as you like... */
+ char name[FILE_NAME_SIZE];
+ png_uint_32 id; /* must be correct (see FILEID) */
+ png_size_t datacount; /* In this (the last) buffer */
+ png_store_buffer data; /* Last buffer in file */
+ int npalette; /* Number of entries in palette */
+ store_palette_entry* palette; /* May be NULL */
+} png_store_file;
+
+/* The following is a pool of memory allocated by a single libpng read or write
+ * operation.
+ */
+typedef struct store_pool
+{
+ struct png_store *store; /* Back pointer */
+ struct store_memory *list; /* List of allocated memory */
+ png_byte mark[4]; /* Before and after data */
+
+ /* Statistics for this run. */
+ png_alloc_size_t max; /* Maximum single allocation */
+ png_alloc_size_t current; /* Current allocation */
+ png_alloc_size_t limit; /* Highest current allocation */
+ png_alloc_size_t total; /* Total allocation */
+
+ /* Overall statistics (retained across successive runs). */
+ png_alloc_size_t max_max;
+ png_alloc_size_t max_limit;
+ png_alloc_size_t max_total;
+} store_pool;
+
+typedef struct png_store
+{
+ /* For cexcept.h exception handling - simply store one of these;
+ * the context is a self pointer but it may point to a different
+ * png_store (in fact it never does in this program.)
+ */
+ struct exception_context
+ exception_context;
+
+ unsigned int verbose :1;
+ unsigned int treat_warnings_as_errors :1;
+ unsigned int expect_error :1;
+ unsigned int expect_warning :1;
+ unsigned int saw_warning :1;
+ unsigned int speed :1;
+ unsigned int progressive :1; /* use progressive read */
+ unsigned int validated :1; /* used as a temporary flag */
+ int nerrors;
+ int nwarnings;
+ int noptions; /* number of options below: */
+ struct {
+ unsigned char option; /* option number, 0..30 */
+ unsigned char setting; /* setting (unset,invalid,on,off) */
+ } options[16];
+ char test[128]; /* Name of test */
+ char error[256];
+
+ /* Read fields */
+ png_structp pread; /* Used to read a saved file */
+ png_infop piread;
+ png_store_file* current; /* Set when reading */
+ png_store_buffer* next; /* Set when reading */
+ png_size_t readpos; /* Position in *next */
+ png_byte* image; /* Buffer for reading interlaced images */
+ png_size_t cb_image; /* Size of this buffer */
+ png_size_t cb_row; /* Row size of the image(s) */
+ png_uint_32 image_h; /* Number of rows in a single image */
+ store_pool read_memory_pool;
+
+ /* Write fields */
+ png_store_file* saved;
+ png_structp pwrite; /* Used when writing a new file */
+ png_infop piwrite;
+ png_size_t writepos; /* Position in .new */
+ char wname[FILE_NAME_SIZE];
+ png_store_buffer new; /* The end of the new PNG file being written. */
+ store_pool write_memory_pool;
+ store_palette_entry* palette;
+ int npalette;
+} png_store;
+
+/* Initialization and cleanup */
+static void
+store_pool_mark(png_bytep mark)
+{
+ static png_uint_32 store_seed[2] = { 0x12345678, 1};
+
+ make_four_random_bytes(store_seed, mark);
+}
+
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
+/* Use this for random 32 bit values; this function makes sure the result is
+ * non-zero.
+ */
+static png_uint_32
+random_32(void)
+{
+
+ for (;;)
+ {
+ png_byte mark[4];
+ png_uint_32 result;
+
+ store_pool_mark(mark);
+ result = png_get_uint_32(mark);
+
+ if (result != 0)
+ return result;
+ }
+}
+#endif /* PNG_READ_SUPPORTED */
+
+static void
+store_pool_init(png_store *ps, store_pool *pool)
+{
+ memset(pool, 0, sizeof *pool);
+
+ pool->store = ps;
+ pool->list = NULL;
+ pool->max = pool->current = pool->limit = pool->total = 0;
+ pool->max_max = pool->max_limit = pool->max_total = 0;
+ store_pool_mark(pool->mark);
+}
+
+static void
+store_init(png_store* ps)
+{
+ memset(ps, 0, sizeof *ps);
+ init_exception_context(&ps->exception_context);
+ store_pool_init(ps, &ps->read_memory_pool);
+ store_pool_init(ps, &ps->write_memory_pool);
+ ps->verbose = 0;
+ ps->treat_warnings_as_errors = 0;
+ ps->expect_error = 0;
+ ps->expect_warning = 0;
+ ps->saw_warning = 0;
+ ps->speed = 0;
+ ps->progressive = 0;
+ ps->validated = 0;
+ ps->nerrors = ps->nwarnings = 0;
+ ps->pread = NULL;
+ ps->piread = NULL;
+ ps->saved = ps->current = NULL;
+ ps->next = NULL;
+ ps->readpos = 0;
+ ps->image = NULL;
+ ps->cb_image = 0;
+ ps->cb_row = 0;
+ ps->image_h = 0;
+ ps->pwrite = NULL;
+ ps->piwrite = NULL;
+ ps->writepos = 0;
+ ps->new.prev = NULL;
+ ps->palette = NULL;
+ ps->npalette = 0;
+ ps->noptions = 0;
+}
+
+static void
+store_freebuffer(png_store_buffer* psb)
+{
+ if (psb->prev)
+ {
+ store_freebuffer(psb->prev);
+ free(psb->prev);
+ psb->prev = NULL;
+ }
+}
+
+static void
+store_freenew(png_store *ps)
+{
+ store_freebuffer(&ps->new);
+ ps->writepos = 0;
+ if (ps->palette != NULL)
+ {
+ free(ps->palette);
+ ps->palette = NULL;
+ ps->npalette = 0;
+ }
+}
+
+static void
+store_storenew(png_store *ps)
+{
+ png_store_buffer *pb;
+
+ if (ps->writepos != STORE_BUFFER_SIZE)
+ png_error(ps->pwrite, "invalid store call");
+
+ pb = voidcast(png_store_buffer*, malloc(sizeof *pb));
+
+ if (pb == NULL)
+ png_error(ps->pwrite, "store new: OOM");
+
+ *pb = ps->new;
+ ps->new.prev = pb;
+ ps->writepos = 0;
+}
+
+static void
+store_freefile(png_store_file **ppf)
+{
+ if (*ppf != NULL)
+ {
+ store_freefile(&(*ppf)->next);
+
+ store_freebuffer(&(*ppf)->data);
+ (*ppf)->datacount = 0;
+ if ((*ppf)->palette != NULL)
+ {
+ free((*ppf)->palette);
+ (*ppf)->palette = NULL;
+ (*ppf)->npalette = 0;
+ }
+ free(*ppf);
+ *ppf = NULL;
+ }
+}
+
+/* Main interface to file storeage, after writing a new PNG file (see the API
+ * below) call store_storefile to store the result with the given name and id.
+ */
+static void
+store_storefile(png_store *ps, png_uint_32 id)
+{
+ png_store_file *pf = voidcast(png_store_file*, malloc(sizeof *pf));
+ if (pf == NULL)
+ png_error(ps->pwrite, "storefile: OOM");
+ safecat(pf->name, sizeof pf->name, 0, ps->wname);
+ pf->id = id;
+ pf->data = ps->new;
+ pf->datacount = ps->writepos;
+ ps->new.prev = NULL;
+ ps->writepos = 0;
+ pf->palette = ps->palette;
+ pf->npalette = ps->npalette;
+ ps->palette = 0;
+ ps->npalette = 0;
+
+ /* And save it. */
+ pf->next = ps->saved;
+ ps->saved = pf;
+}
+
+/* Generate an error message (in the given buffer) */
+static size_t
+store_message(png_store *ps, png_const_structp pp, char *buffer, size_t bufsize,
+ size_t pos, const char *msg)
+{
+ if (pp != NULL && pp == ps->pread)
+ {
+ /* Reading a file */
+ pos = safecat(buffer, bufsize, pos, "read: ");
+
+ if (ps->current != NULL)
+ {
+ pos = safecat(buffer, bufsize, pos, ps->current->name);
+ pos = safecat(buffer, bufsize, pos, sep);
+ }
+ }
+
+ else if (pp != NULL && pp == ps->pwrite)
+ {
+ /* Writing a file */
+ pos = safecat(buffer, bufsize, pos, "write: ");
+ pos = safecat(buffer, bufsize, pos, ps->wname);
+ pos = safecat(buffer, bufsize, pos, sep);
+ }
+
+ else
+ {
+ /* Neither reading nor writing (or a memory error in struct delete) */
+ pos = safecat(buffer, bufsize, pos, "pngvalid: ");
+ }
+
+ if (ps->test[0] != 0)
+ {
+ pos = safecat(buffer, bufsize, pos, ps->test);
+ pos = safecat(buffer, bufsize, pos, sep);
+ }
+ pos = safecat(buffer, bufsize, pos, msg);
+ return pos;
+}
+
+/* Verbose output to the error stream: */
+static void
+store_verbose(png_store *ps, png_const_structp pp, png_const_charp prefix,
+ png_const_charp message)
+{
+ char buffer[512];
+
+ if (prefix)
+ fputs(prefix, stderr);
+
+ (void)store_message(ps, pp, buffer, sizeof buffer, 0, message);
+ fputs(buffer, stderr);
+ fputc('\n', stderr);
+}
+
+/* Log an error or warning - the relevant count is always incremented. */
+static void
+store_log(png_store* ps, png_const_structp pp, png_const_charp message,
+ int is_error)
+{
+ /* The warning is copied to the error buffer if there are no errors and it is
+ * the first warning. The error is copied to the error buffer if it is the
+ * first error (overwriting any prior warnings).
+ */
+ if (is_error ? (ps->nerrors)++ == 0 :
+ (ps->nwarnings)++ == 0 && ps->nerrors == 0)
+ store_message(ps, pp, ps->error, sizeof ps->error, 0, message);
+
+ if (ps->verbose)
+ store_verbose(ps, pp, is_error ? "error: " : "warning: ", message);
+}
+
+#ifdef PNG_READ_SUPPORTED
+/* Internal error function, called with a png_store but no libpng stuff. */
+static void
+internal_error(png_store *ps, png_const_charp message)
+{
+ store_log(ps, NULL, message, 1 /* error */);
+
+ /* And finally throw an exception. */
+ {
+ struct exception_context *the_exception_context = &ps->exception_context;
+ Throw ps;
+ }
+}
+#endif /* PNG_READ_SUPPORTED */
+
+/* Functions to use as PNG callbacks. */
+static void PNGCBAPI
+store_error(png_structp ppIn, png_const_charp message) /* PNG_NORETURN */
+{
+ png_const_structp pp = ppIn;
+ png_store *ps = voidcast(png_store*, png_get_error_ptr(pp));
+
+ if (!ps->expect_error)
+ store_log(ps, pp, message, 1 /* error */);
+
+ /* And finally throw an exception. */
+ {
+ struct exception_context *the_exception_context = &ps->exception_context;
+ Throw ps;
+ }
+}
+
+static void PNGCBAPI
+store_warning(png_structp ppIn, png_const_charp message)
+{
+ png_const_structp pp = ppIn;
+ png_store *ps = voidcast(png_store*, png_get_error_ptr(pp));
+
+ if (!ps->expect_warning)
+ store_log(ps, pp, message, 0 /* warning */);
+ else
+ ps->saw_warning = 1;
+}
+
+/* These somewhat odd functions are used when reading an image to ensure that
+ * the buffer is big enough, the png_structp is for errors.
+ */
+/* Return a single row from the correct image. */
+static png_bytep
+store_image_row(const png_store* ps, png_const_structp pp, int nImage,
+ png_uint_32 y)
+{
+ png_size_t coffset = (nImage * ps->image_h + y) * (ps->cb_row + 5) + 2;
+
+ if (ps->image == NULL)
+ png_error(pp, "no allocated image");
+
+ if (coffset + ps->cb_row + 3 > ps->cb_image)
+ png_error(pp, "image too small");
+
+ return ps->image + coffset;
+}
+
+static void
+store_image_free(png_store *ps, png_const_structp pp)
+{
+ if (ps->image != NULL)
+ {
+ png_bytep image = ps->image;
+
+ if (image[-1] != 0xed || image[ps->cb_image] != 0xfe)
+ {
+ if (pp != NULL)
+ png_error(pp, "png_store image overwrite (1)");
+ else
+ store_log(ps, NULL, "png_store image overwrite (2)", 1);
+ }
+
+ ps->image = NULL;
+ ps->cb_image = 0;
+ --image;
+ free(image);
+ }
+}
+
+static void
+store_ensure_image(png_store *ps, png_const_structp pp, int nImages,
+ png_size_t cbRow, png_uint_32 cRows)
+{
+ png_size_t cb = nImages * cRows * (cbRow + 5);
+
+ if (ps->cb_image < cb)
+ {
+ png_bytep image;
+
+ store_image_free(ps, pp);
+
+ /* The buffer is deliberately mis-aligned. */
+ image = voidcast(png_bytep, malloc(cb+2));
+ if (image == NULL)
+ {
+ /* Called from the startup - ignore the error for the moment. */
+ if (pp == NULL)
+ return;
+
+ png_error(pp, "OOM allocating image buffer");
+ }
+
+ /* These magic tags are used to detect overwrites above. */
+ ++image;
+ image[-1] = 0xed;
+ image[cb] = 0xfe;
+
+ ps->image = image;
+ ps->cb_image = cb;
+ }
+
+ /* We have an adequate sized image; lay out the rows. There are 2 bytes at
+ * the start and three at the end of each (this ensures that the row
+ * alignment starts out odd - 2+1 and changes for larger images on each row.)
+ */
+ ps->cb_row = cbRow;
+ ps->image_h = cRows;
+
+ /* For error checking, the whole buffer is set to 10110010 (0xb2 - 178).
+ * This deliberately doesn't match the bits in the size test image which are
+ * outside the image; these are set to 0xff (all 1). To make the row
+ * comparison work in the 'size' test case the size rows are pre-initialized
+ * to the same value prior to calling 'standard_row'.
+ */
+ memset(ps->image, 178, cb);
+
+ /* Then put in the marks. */
+ while (--nImages >= 0)
+ {
+ png_uint_32 y;
+
+ for (y=0; y<cRows; ++y)
+ {
+ png_bytep row = store_image_row(ps, pp, nImages, y);
+
+ /* The markers: */
+ row[-2] = 190;
+ row[-1] = 239;
+ row[cbRow] = 222;
+ row[cbRow+1] = 173;
+ row[cbRow+2] = 17;
+ }
+ }
+}
+
+#ifdef PNG_READ_SUPPORTED
+static void
+store_image_check(const png_store* ps, png_const_structp pp, int iImage)
+{
+ png_const_bytep image = ps->image;
+
+ if (image[-1] != 0xed || image[ps->cb_image] != 0xfe)
+ png_error(pp, "image overwrite");
+ else
+ {
+ png_size_t cbRow = ps->cb_row;
+ png_uint_32 rows = ps->image_h;
+
+ image += iImage * (cbRow+5) * ps->image_h;
+
+ image += 2; /* skip image first row markers */
+
+ while (rows-- > 0)
+ {
+ if (image[-2] != 190 || image[-1] != 239)
+ png_error(pp, "row start overwritten");
+
+ if (image[cbRow] != 222 || image[cbRow+1] != 173 ||
+ image[cbRow+2] != 17)
+ png_error(pp, "row end overwritten");
+
+ image += cbRow+5;
+ }
+ }
+}
+#endif /* PNG_READ_SUPPORTED */
+
+static void PNGCBAPI
+store_write(png_structp ppIn, png_bytep pb, png_size_t st)
+{
+ png_const_structp pp = ppIn;
+ png_store *ps = voidcast(png_store*, png_get_io_ptr(pp));
+
+ if (ps->pwrite != pp)
+ png_error(pp, "store state damaged");
+
+ while (st > 0)
+ {
+ size_t cb;
+
+ if (ps->writepos >= STORE_BUFFER_SIZE)
+ store_storenew(ps);
+
+ cb = st;
+
+ if (cb > STORE_BUFFER_SIZE - ps->writepos)
+ cb = STORE_BUFFER_SIZE - ps->writepos;
+
+ memcpy(ps->new.buffer + ps->writepos, pb, cb);
+ pb += cb;
+ st -= cb;
+ ps->writepos += cb;
+ }
+}
+
+static void PNGCBAPI
+store_flush(png_structp ppIn)
+{
+ UNUSED(ppIn) /*DOES NOTHING*/
+}
+
+#ifdef PNG_READ_SUPPORTED
+static size_t
+store_read_buffer_size(png_store *ps)
+{
+ /* Return the bytes available for read in the current buffer. */
+ if (ps->next != &ps->current->data)
+ return STORE_BUFFER_SIZE;
+
+ return ps->current->datacount;
+}
+
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
+/* Return total bytes available for read. */
+static size_t
+store_read_buffer_avail(png_store *ps)
+{
+ if (ps->current != NULL && ps->next != NULL)
+ {
+ png_store_buffer *next = &ps->current->data;
+ size_t cbAvail = ps->current->datacount;
+
+ while (next != ps->next && next != NULL)
+ {
+ next = next->prev;
+ cbAvail += STORE_BUFFER_SIZE;
+ }
+
+ if (next != ps->next)
+ png_error(ps->pread, "buffer read error");
+
+ if (cbAvail > ps->readpos)
+ return cbAvail - ps->readpos;
+ }
+
+ return 0;
+}
+#endif
+
+static int
+store_read_buffer_next(png_store *ps)
+{
+ png_store_buffer *pbOld = ps->next;
+ png_store_buffer *pbNew = &ps->current->data;
+ if (pbOld != pbNew)
+ {
+ while (pbNew != NULL && pbNew->prev != pbOld)
+ pbNew = pbNew->prev;
+
+ if (pbNew != NULL)
+ {
+ ps->next = pbNew;
+ ps->readpos = 0;
+ return 1;
+ }
+
+ png_error(ps->pread, "buffer lost");
+ }
+
+ return 0; /* EOF or error */
+}
+
+/* Need separate implementation and callback to allow use of the same code
+ * during progressive read, where the io_ptr is set internally by libpng.
+ */
+static void
+store_read_imp(png_store *ps, png_bytep pb, png_size_t st)
+{
+ if (ps->current == NULL || ps->next == NULL)
+ png_error(ps->pread, "store state damaged");
+
+ while (st > 0)
+ {
+ size_t cbAvail = store_read_buffer_size(ps) - ps->readpos;
+
+ if (cbAvail > 0)
+ {
+ if (cbAvail > st) cbAvail = st;
+ memcpy(pb, ps->next->buffer + ps->readpos, cbAvail);
+ st -= cbAvail;
+ pb += cbAvail;
+ ps->readpos += cbAvail;
+ }
+
+ else if (!store_read_buffer_next(ps))
+ png_error(ps->pread, "read beyond end of file");
+ }
+}
+
+static void PNGCBAPI
+store_read(png_structp ppIn, png_bytep pb, png_size_t st)
+{
+ png_const_structp pp = ppIn;
+ png_store *ps = voidcast(png_store*, png_get_io_ptr(pp));
+
+ if (ps == NULL || ps->pread != pp)
+ png_error(pp, "bad store read call");
+
+ store_read_imp(ps, pb, st);
+}
+
+static void
+store_progressive_read(png_store *ps, png_structp pp, png_infop pi)
+{
+ /* Notice that a call to store_read will cause this function to fail because
+ * readpos will be set.
+ */
+ if (ps->pread != pp || ps->current == NULL || ps->next == NULL)
+ png_error(pp, "store state damaged (progressive)");
+
+ do
+ {
+ if (ps->readpos != 0)
+ png_error(pp, "store_read called during progressive read");
+
+ png_process_data(pp, pi, ps->next->buffer, store_read_buffer_size(ps));
+ }
+ while (store_read_buffer_next(ps));
+}
+#endif /* PNG_READ_SUPPORTED */
+
+/* The caller must fill this in: */
+static store_palette_entry *
+store_write_palette(png_store *ps, int npalette)
+{
+ if (ps->pwrite == NULL)
+ store_log(ps, NULL, "attempt to write palette without write stream", 1);
+
+ if (ps->palette != NULL)
+ png_error(ps->pwrite, "multiple store_write_palette calls");
+
+ /* This function can only return NULL if called with '0'! */
+ if (npalette > 0)
+ {
+ ps->palette = voidcast(store_palette_entry*, malloc(npalette *
+ sizeof *ps->palette));
+
+ if (ps->palette == NULL)
+ png_error(ps->pwrite, "store new palette: OOM");
+
+ ps->npalette = npalette;
+ }
+
+ return ps->palette;
+}
+
+#ifdef PNG_READ_SUPPORTED
+static store_palette_entry *
+store_current_palette(png_store *ps, int *npalette)
+{
+ /* This is an internal error (the call has been made outside a read
+ * operation.)
+ */
+ if (ps->current == NULL)
+ {
+ store_log(ps, ps->pread, "no current stream for palette", 1);
+ return NULL;
+ }
+
+ /* The result may be null if there is no palette. */
+ *npalette = ps->current->npalette;
+ return ps->current->palette;
+}
+#endif /* PNG_READ_SUPPORTED */
+
+/***************************** MEMORY MANAGEMENT*** ***************************/
+#ifdef PNG_USER_MEM_SUPPORTED
+/* A store_memory is simply the header for an allocated block of memory. The
+ * pointer returned to libpng is just after the end of the header block, the
+ * allocated memory is followed by a second copy of the 'mark'.
+ */
+typedef struct store_memory
+{
+ store_pool *pool; /* Originating pool */
+ struct store_memory *next; /* Singly linked list */
+ png_alloc_size_t size; /* Size of memory allocated */
+ png_byte mark[4]; /* ID marker */
+} store_memory;
+
+/* Handle a fatal error in memory allocation. This calls png_error if the
+ * libpng struct is non-NULL, else it outputs a message and returns. This means
+ * that a memory problem while libpng is running will abort (png_error) the
+ * handling of particular file while one in cleanup (after the destroy of the
+ * struct has returned) will simply keep going and free (or attempt to free)
+ * all the memory.
+ */
+static void
+store_pool_error(png_store *ps, png_const_structp pp, const char *msg)
+{
+ if (pp != NULL)
+ png_error(pp, msg);
+
+ /* Else we have to do it ourselves. png_error eventually calls store_log,
+ * above. store_log accepts a NULL png_structp - it just changes what gets
+ * output by store_message.
+ */
+ store_log(ps, pp, msg, 1 /* error */);
+}
+
+static void
+store_memory_free(png_const_structp pp, store_pool *pool, store_memory *memory)
+{
+ /* Note that pp may be NULL (see store_pool_delete below), the caller has
+ * found 'memory' in pool->list *and* unlinked this entry, so this is a valid
+ * pointer (for sure), but the contents may have been trashed.
+ */
+ if (memory->pool != pool)
+ store_pool_error(pool->store, pp, "memory corrupted (pool)");
+
+ else if (memcmp(memory->mark, pool->mark, sizeof memory->mark) != 0)
+ store_pool_error(pool->store, pp, "memory corrupted (start)");
+
+ /* It should be safe to read the size field now. */
+ else
+ {
+ png_alloc_size_t cb = memory->size;
+
+ if (cb > pool->max)
+ store_pool_error(pool->store, pp, "memory corrupted (size)");
+
+ else if (memcmp((png_bytep)(memory+1)+cb, pool->mark, sizeof pool->mark)
+ != 0)
+ store_pool_error(pool->store, pp, "memory corrupted (end)");
+
+ /* Finally give the library a chance to find problems too: */
+ else
+ {
+ pool->current -= cb;
+ free(memory);
+ }
+ }
+}
+
+static void
+store_pool_delete(png_store *ps, store_pool *pool)
+{
+ if (pool->list != NULL)
+ {
+ fprintf(stderr, "%s: %s %s: memory lost (list follows):\n", ps->test,
+ pool == &ps->read_memory_pool ? "read" : "write",
+ pool == &ps->read_memory_pool ? (ps->current != NULL ?
+ ps->current->name : "unknown file") : ps->wname);
+ ++ps->nerrors;
+
+ do
+ {
+ store_memory *next = pool->list;
+ pool->list = next->next;
+ next->next = NULL;
+
+ fprintf(stderr, "\t%lu bytes @ %p\n",
+ (unsigned long)next->size, (const void*)(next+1));
+ /* The NULL means this will always return, even if the memory is
+ * corrupted.
+ */
+ store_memory_free(NULL, pool, next);
+ }
+ while (pool->list != NULL);
+ }
+
+ /* And reset the other fields too for the next time. */
+ if (pool->max > pool->max_max) pool->max_max = pool->max;
+ pool->max = 0;
+ if (pool->current != 0) /* unexpected internal error */
+ fprintf(stderr, "%s: %s %s: memory counter mismatch (internal error)\n",
+ ps->test, pool == &ps->read_memory_pool ? "read" : "write",
+ pool == &ps->read_memory_pool ? (ps->current != NULL ?
+ ps->current->name : "unknown file") : ps->wname);
+ pool->current = 0;
+
+ if (pool->limit > pool->max_limit)
+ pool->max_limit = pool->limit;
+
+ pool->limit = 0;
+
+ if (pool->total > pool->max_total)
+ pool->max_total = pool->total;
+
+ pool->total = 0;
+
+ /* Get a new mark too. */
+ store_pool_mark(pool->mark);
+}
+
+/* The memory callbacks: */
+static png_voidp PNGCBAPI
+store_malloc(png_structp ppIn, png_alloc_size_t cb)
+{
+ png_const_structp pp = ppIn;
+ store_pool *pool = voidcast(store_pool*, png_get_mem_ptr(pp));
+ store_memory *new = voidcast(store_memory*, malloc(cb + (sizeof *new) +
+ (sizeof pool->mark)));
+
+ if (new != NULL)
+ {
+ if (cb > pool->max)
+ pool->max = cb;
+
+ pool->current += cb;
+
+ if (pool->current > pool->limit)
+ pool->limit = pool->current;
+
+ pool->total += cb;
+
+ new->size = cb;
+ memcpy(new->mark, pool->mark, sizeof new->mark);
+ memcpy((png_byte*)(new+1) + cb, pool->mark, sizeof pool->mark);
+ new->pool = pool;
+ new->next = pool->list;
+ pool->list = new;
+ ++new;
+ }
+
+ else
+ {
+ /* NOTE: the PNG user malloc function cannot use the png_ptr it is passed
+ * other than to retrieve the allocation pointer! libpng calls the
+ * store_malloc callback in two basic cases:
+ *
+ * 1) From png_malloc; png_malloc will do a png_error itself if NULL is
+ * returned.
+ * 2) From png_struct or png_info structure creation; png_malloc is
+ * to return so cleanup can be performed.
+ *
+ * To handle this store_malloc can log a message, but can't do anything
+ * else.
+ */
+ store_log(pool->store, pp, "out of memory", 1 /* is_error */);
+ }
+
+ return new;
+}
+
+static void PNGCBAPI
+store_free(png_structp ppIn, png_voidp memory)
+{
+ png_const_structp pp = ppIn;
+ store_pool *pool = voidcast(store_pool*, png_get_mem_ptr(pp));
+ store_memory *this = voidcast(store_memory*, memory), **test;
+
+ /* Because libpng calls store_free with a dummy png_struct when deleting
+ * png_struct or png_info via png_destroy_struct_2 it is necessary to check
+ * the passed in png_structp to ensure it is valid, and not pass it to
+ * png_error if it is not.
+ */
+ if (pp != pool->store->pread && pp != pool->store->pwrite)
+ pp = NULL;
+
+ /* First check that this 'memory' really is valid memory - it must be in the
+ * pool list. If it is, use the shared memory_free function to free it.
+ */
+ --this;
+ for (test = &pool->list; *test != this; test = &(*test)->next)
+ {
+ if (*test == NULL)
+ {
+ store_pool_error(pool->store, pp, "bad pointer to free");
+ return;
+ }
+ }
+
+ /* Unlink this entry, *test == this. */
+ *test = this->next;
+ this->next = NULL;
+ store_memory_free(pp, pool, this);
+}
+#endif /* PNG_USER_MEM_SUPPORTED */
+
+/* Setup functions. */
+/* Cleanup when aborting a write or after storing the new file. */
+static void
+store_write_reset(png_store *ps)
+{
+ if (ps->pwrite != NULL)
+ {
+ anon_context(ps);
+
+ Try
+ png_destroy_write_struct(&ps->pwrite, &ps->piwrite);
+
+ Catch_anonymous
+ {
+ /* memory corruption: continue. */
+ }
+
+ ps->pwrite = NULL;
+ ps->piwrite = NULL;
+ }
+
+ /* And make sure that all the memory has been freed - this will output
+ * spurious errors in the case of memory corruption above, but this is safe.
+ */
+# ifdef PNG_USER_MEM_SUPPORTED
+ store_pool_delete(ps, &ps->write_memory_pool);
+# endif
+
+ store_freenew(ps);
+}
+
+/* The following is the main write function, it returns a png_struct and,
+ * optionally, a png_info suitable for writiing a new PNG file. Use
+ * store_storefile above to record this file after it has been written. The
+ * returned libpng structures as destroyed by store_write_reset above.
+ */
+static png_structp
+set_store_for_write(png_store *ps, png_infopp ppi, const char *name)
+{
+ anon_context(ps);
+
+ Try
+ {
+ if (ps->pwrite != NULL)
+ png_error(ps->pwrite, "write store already in use");
+
+ store_write_reset(ps);
+ safecat(ps->wname, sizeof ps->wname, 0, name);
+
+ /* Don't do the slow memory checks if doing a speed test, also if user
+ * memory is not supported we can't do it anyway.
+ */
+# ifdef PNG_USER_MEM_SUPPORTED
+ if (!ps->speed)
+ ps->pwrite = png_create_write_struct_2(PNG_LIBPNG_VER_STRING,
+ ps, store_error, store_warning, &ps->write_memory_pool,
+ store_malloc, store_free);
+
+ else
+# endif
+ ps->pwrite = png_create_write_struct(PNG_LIBPNG_VER_STRING,
+ ps, store_error, store_warning);
+
+ png_set_write_fn(ps->pwrite, ps, store_write, store_flush);
+
+# ifdef PNG_SET_OPTION_SUPPORTED
+ {
+ int opt;
+ for (opt=0; opt<ps->noptions; ++opt)
+ if (png_set_option(ps->pwrite, ps->options[opt].option,
+ ps->options[opt].setting) == PNG_OPTION_INVALID)
+ png_error(ps->pwrite, "png option invalid");
+ }
+# endif
+
+ if (ppi != NULL)
+ *ppi = ps->piwrite = png_create_info_struct(ps->pwrite);
+ }
+
+ Catch_anonymous
+ return NULL;
+
+ return ps->pwrite;
+}
+
+/* Cleanup when finished reading (either due to error or in the success case).
+ * This routine exists even when there is no read support to make the code
+ * tidier (avoid a mass of ifdefs) and so easier to maintain.
+ */
+static void
+store_read_reset(png_store *ps)
+{
+# ifdef PNG_READ_SUPPORTED
+ if (ps->pread != NULL)
+ {
+ anon_context(ps);
+
+ Try
+ png_destroy_read_struct(&ps->pread, &ps->piread, NULL);
+
+ Catch_anonymous
+ {
+ /* error already output: continue */
+ }
+
+ ps->pread = NULL;
+ ps->piread = NULL;
+ }
+# endif
+
+# ifdef PNG_USER_MEM_SUPPORTED
+ /* Always do this to be safe. */
+ store_pool_delete(ps, &ps->read_memory_pool);
+# endif
+
+ ps->current = NULL;
+ ps->next = NULL;
+ ps->readpos = 0;
+ ps->validated = 0;
+}
+
+#ifdef PNG_READ_SUPPORTED
+static void
+store_read_set(png_store *ps, png_uint_32 id)
+{
+ png_store_file *pf = ps->saved;
+
+ while (pf != NULL)
+ {
+ if (pf->id == id)
+ {
+ ps->current = pf;
+ ps->next = NULL;
+ store_read_buffer_next(ps);
+ return;
+ }
+
+ pf = pf->next;
+ }
+
+ {
+ size_t pos;
+ char msg[FILE_NAME_SIZE+64];
+
+ pos = standard_name_from_id(msg, sizeof msg, 0, id);
+ pos = safecat(msg, sizeof msg, pos, ": file not found");
+ png_error(ps->pread, msg);
+ }
+}
+
+/* The main interface for reading a saved file - pass the id number of the file
+ * to retrieve. Ids must be unique or the earlier file will be hidden. The API
+ * returns a png_struct and, optionally, a png_info. Both of these will be
+ * destroyed by store_read_reset above.
+ */
+static png_structp
+set_store_for_read(png_store *ps, png_infopp ppi, png_uint_32 id,
+ const char *name)
+{
+ /* Set the name for png_error */
+ safecat(ps->test, sizeof ps->test, 0, name);
+
+ if (ps->pread != NULL)
+ png_error(ps->pread, "read store already in use");
+
+ store_read_reset(ps);
+
+ /* Both the create APIs can return NULL if used in their default mode
+ * (because there is no other way of handling an error because the jmp_buf
+ * by default is stored in png_struct and that has not been allocated!)
+ * However, given that store_error works correctly in these circumstances
+ * we don't ever expect NULL in this program.
+ */
+# ifdef PNG_USER_MEM_SUPPORTED
+ if (!ps->speed)
+ ps->pread = png_create_read_struct_2(PNG_LIBPNG_VER_STRING, ps,
+ store_error, store_warning, &ps->read_memory_pool, store_malloc,
+ store_free);
+
+ else
+# endif
+ ps->pread = png_create_read_struct(PNG_LIBPNG_VER_STRING, ps, store_error,
+ store_warning);
+
+ if (ps->pread == NULL)
+ {
+ struct exception_context *the_exception_context = &ps->exception_context;
+
+ store_log(ps, NULL, "png_create_read_struct returned NULL (unexpected)",
+ 1 /*error*/);
+
+ Throw ps;
+ }
+
+# ifdef PNG_SET_OPTION_SUPPORTED
+ {
+ int opt;
+ for (opt=0; opt<ps->noptions; ++opt)
+ if (png_set_option(ps->pread, ps->options[opt].option,
+ ps->options[opt].setting) == PNG_OPTION_INVALID)
+ png_error(ps->pread, "png option invalid");
+ }
+# endif
+
+ store_read_set(ps, id);
+
+ if (ppi != NULL)
+ *ppi = ps->piread = png_create_info_struct(ps->pread);
+
+ return ps->pread;
+}
+#endif /* PNG_READ_SUPPORTED */
+
+/* The overall cleanup of a store simply calls the above then removes all the
+ * saved files. This does not delete the store itself.
+ */
+static void
+store_delete(png_store *ps)
+{
+ store_write_reset(ps);
+ store_read_reset(ps);
+ store_freefile(&ps->saved);
+ store_image_free(ps, NULL);
+}
+
+/*********************** PNG FILE MODIFICATION ON READ ************************/
+/* Files may be modified on read. The following structure contains a complete
+ * png_store together with extra members to handle modification and a special
+ * read callback for libpng. To use this the 'modifications' field must be set
+ * to a list of png_modification structures that actually perform the
+ * modification, otherwise a png_modifier is functionally equivalent to a
+ * png_store. There is a special read function, set_modifier_for_read, which
+ * replaces set_store_for_read.
+ */
+typedef enum modifier_state
+{
+ modifier_start, /* Initial value */
+ modifier_signature, /* Have a signature */
+ modifier_IHDR /* Have an IHDR */
+} modifier_state;
+
+typedef struct CIE_color
+{
+ /* A single CIE tristimulus value, representing the unique response of a
+ * standard observer to a variety of light spectra. The observer recognizes
+ * all spectra that produce this response as the same color, therefore this
+ * is effectively a description of a color.
+ */
+ double X, Y, Z;
+} CIE_color;
+
+typedef struct color_encoding
+{
+ /* A description of an (R,G,B) encoding of color (as defined above); this
+ * includes the actual colors of the (R,G,B) triples (1,0,0), (0,1,0) and
+ * (0,0,1) plus an encoding value that is used to encode the linear
+ * components R, G and B to give the actual values R^gamma, G^gamma and
+ * B^gamma that are stored.
+ */
+ double gamma; /* Encoding (file) gamma of space */
+ CIE_color red, green, blue; /* End points */
+} color_encoding;
+
+#ifdef PNG_READ_SUPPORTED
+#if defined PNG_READ_TRANSFORMS_SUPPORTED && defined PNG_READ_cHRM_SUPPORTED
+static double
+chromaticity_x(CIE_color c)
+{
+ return c.X / (c.X + c.Y + c.Z);
+}
+
+static double
+chromaticity_y(CIE_color c)
+{
+ return c.Y / (c.X + c.Y + c.Z);
+}
+
+static CIE_color
+white_point(const color_encoding *encoding)
+{
+ CIE_color white;
+
+ white.X = encoding->red.X + encoding->green.X + encoding->blue.X;
+ white.Y = encoding->red.Y + encoding->green.Y + encoding->blue.Y;
+ white.Z = encoding->red.Z + encoding->green.Z + encoding->blue.Z;
+
+ return white;
+}
+#endif /* READ_TRANSFORMS && READ_cHRM */
+
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+static void
+normalize_color_encoding(color_encoding *encoding)
+{
+ const double whiteY = encoding->red.Y + encoding->green.Y +
+ encoding->blue.Y;
+
+ if (whiteY != 1)
+ {
+ encoding->red.X /= whiteY;
+ encoding->red.Y /= whiteY;
+ encoding->red.Z /= whiteY;
+ encoding->green.X /= whiteY;
+ encoding->green.Y /= whiteY;
+ encoding->green.Z /= whiteY;
+ encoding->blue.X /= whiteY;
+ encoding->blue.Y /= whiteY;
+ encoding->blue.Z /= whiteY;
+ }
+}
+#endif
+
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
+static size_t
+safecat_color_encoding(char *buffer, size_t bufsize, size_t pos,
+ const color_encoding *e, double encoding_gamma)
+{
+ if (e != 0)
+ {
+ if (encoding_gamma != 0)
+ pos = safecat(buffer, bufsize, pos, "(");
+ pos = safecat(buffer, bufsize, pos, "R(");
+ pos = safecatd(buffer, bufsize, pos, e->red.X, 4);
+ pos = safecat(buffer, bufsize, pos, ",");
+ pos = safecatd(buffer, bufsize, pos, e->red.Y, 4);
+ pos = safecat(buffer, bufsize, pos, ",");
+ pos = safecatd(buffer, bufsize, pos, e->red.Z, 4);
+ pos = safecat(buffer, bufsize, pos, "),G(");
+ pos = safecatd(buffer, bufsize, pos, e->green.X, 4);
+ pos = safecat(buffer, bufsize, pos, ",");
+ pos = safecatd(buffer, bufsize, pos, e->green.Y, 4);
+ pos = safecat(buffer, bufsize, pos, ",");
+ pos = safecatd(buffer, bufsize, pos, e->green.Z, 4);
+ pos = safecat(buffer, bufsize, pos, "),B(");
+ pos = safecatd(buffer, bufsize, pos, e->blue.X, 4);
+ pos = safecat(buffer, bufsize, pos, ",");
+ pos = safecatd(buffer, bufsize, pos, e->blue.Y, 4);
+ pos = safecat(buffer, bufsize, pos, ",");
+ pos = safecatd(buffer, bufsize, pos, e->blue.Z, 4);
+ pos = safecat(buffer, bufsize, pos, ")");
+ if (encoding_gamma != 0)
+ pos = safecat(buffer, bufsize, pos, ")");
+ }
+
+ if (encoding_gamma != 0)
+ {
+ pos = safecat(buffer, bufsize, pos, "^");
+ pos = safecatd(buffer, bufsize, pos, encoding_gamma, 5);
+ }
+
+ return pos;
+}
+#endif /* READ_TRANSFORMS */
+#endif /* PNG_READ_SUPPORTED */
+
+typedef struct png_modifier
+{
+ png_store this; /* I am a png_store */
+ struct png_modification *modifications; /* Changes to make */
+
+ modifier_state state; /* My state */
+
+ /* Information from IHDR: */
+ png_byte bit_depth; /* From IHDR */
+ png_byte colour_type; /* From IHDR */
+
+ /* While handling PLTE, IDAT and IEND these chunks may be pended to allow
+ * other chunks to be inserted.
+ */
+ png_uint_32 pending_len;
+ png_uint_32 pending_chunk;
+
+ /* Test values */
+ double *gammas;
+ unsigned int ngammas;
+ unsigned int ngamma_tests; /* Number of gamma tests to run*/
+ double current_gamma; /* 0 if not set */
+ const color_encoding *encodings;
+ unsigned int nencodings;
+ const color_encoding *current_encoding; /* If an encoding has been set */
+ unsigned int encoding_counter; /* For iteration */
+ int encoding_ignored; /* Something overwrote it */
+
+ /* Control variables used to iterate through possible encodings, the
+ * following must be set to 0 and tested by the function that uses the
+ * png_modifier because the modifier only sets it to 1 (true.)
+ */
+ unsigned int repeat :1; /* Repeat this transform test. */
+ unsigned int test_uses_encoding :1;
+
+ /* Lowest sbit to test (pre-1.7 libpng fails for sbit < 8) */
+ png_byte sbitlow;
+
+ /* Error control - these are the limits on errors accepted by the gamma tests
+ * below.
+ */
+ double maxout8; /* Maximum output value error */
+ double maxabs8; /* Absolute sample error 0..1 */
+ double maxcalc8; /* Absolute sample error 0..1 */
+ double maxpc8; /* Percentage sample error 0..100% */
+ double maxout16; /* Maximum output value error */
+ double maxabs16; /* Absolute sample error 0..1 */
+ double maxcalc16;/* Absolute sample error 0..1 */
+ double maxcalcG; /* Absolute sample error 0..1 */
+ double maxpc16; /* Percentage sample error 0..100% */
+
+ /* This is set by transforms that need to allow a higher limit, it is an
+ * internal check on pngvalid to ensure that the calculated error limits are
+ * not ridiculous; without this it is too easy to make a mistake in pngvalid
+ * that allows any value through.
+ */
+ double limit; /* limit on error values, normally 4E-3 */
+
+ /* Log limits - values above this are logged, but not necessarily
+ * warned.
+ */
+ double log8; /* Absolute error in 8 bits to log */
+ double log16; /* Absolute error in 16 bits to log */
+
+ /* Logged 8 and 16 bit errors ('output' values): */
+ double error_gray_2;
+ double error_gray_4;
+ double error_gray_8;
+ double error_gray_16;
+ double error_color_8;
+ double error_color_16;
+ double error_indexed;
+
+ /* Flags: */
+ /* Whether to call png_read_update_info, not png_read_start_image, and how
+ * many times to call it.
+ */
+ int use_update_info;
+
+ /* Whether or not to interlace. */
+ int interlace_type :9; /* int, but must store '1' */
+
+ /* Run the standard tests? */
+ unsigned int test_standard :1;
+
+ /* Run the odd-sized image and interlace read/write tests? */
+ unsigned int test_size :1;
+
+ /* Run tests on reading with a combination of transforms, */
+ unsigned int test_transform :1;
+ unsigned int test_tRNS :1; /* Includes tRNS images */
+
+ /* When to use the use_input_precision option, this controls the gamma
+ * validation code checks. If set any value that is within the transformed
+ * range input-.5 to input+.5 will be accepted, otherwise the value must be
+ * within the normal limits. It should not be necessary to set this; the
+ * result should always be exact within the permitted error limits.
+ */
+ unsigned int use_input_precision :1;
+ unsigned int use_input_precision_sbit :1;
+ unsigned int use_input_precision_16to8 :1;
+
+ /* If set assume that the calculation bit depth is set by the input
+ * precision, not the output precision.
+ */
+ unsigned int calculations_use_input_precision :1;
+
+ /* If set assume that the calculations are done in 16 bits even if the sample
+ * depth is 8 bits.
+ */
+ unsigned int assume_16_bit_calculations :1;
+
+ /* Which gamma tests to run: */
+ unsigned int test_gamma_threshold :1;
+ unsigned int test_gamma_transform :1; /* main tests */
+ unsigned int test_gamma_sbit :1;
+ unsigned int test_gamma_scale16 :1;
+ unsigned int test_gamma_background :1;
+ unsigned int test_gamma_alpha_mode :1;
+ unsigned int test_gamma_expand16 :1;
+ unsigned int test_exhaustive :1;
+
+ /* Whether or not to run the low-bit-depth grayscale tests. This fails on
+ * gamma images in some cases because of gross inaccuracies in the grayscale
+ * gamma handling for low bit depth.
+ */
+ unsigned int test_lbg :1;
+ unsigned int test_lbg_gamma_threshold :1;
+ unsigned int test_lbg_gamma_transform :1;
+ unsigned int test_lbg_gamma_sbit :1;
+ unsigned int test_lbg_gamma_composition :1;
+
+ unsigned int log :1; /* Log max error */
+
+ /* Buffer information, the buffer size limits the size of the chunks that can
+ * be modified - they must fit (including header and CRC) into the buffer!
+ */
+ size_t flush; /* Count of bytes to flush */
+ size_t buffer_count; /* Bytes in buffer */
+ size_t buffer_position; /* Position in buffer */
+ png_byte buffer[1024];
+} png_modifier;
+
+/* This returns true if the test should be stopped now because it has already
+ * failed and it is running silently.
+ */
+static int fail(png_modifier *pm)
+{
+ return !pm->log && !pm->this.verbose && (pm->this.nerrors > 0 ||
+ (pm->this.treat_warnings_as_errors && pm->this.nwarnings > 0));
+}
+
+static void
+modifier_init(png_modifier *pm)
+{
+ memset(pm, 0, sizeof *pm);
+ store_init(&pm->this);
+ pm->modifications = NULL;
+ pm->state = modifier_start;
+ pm->sbitlow = 1U;
+ pm->ngammas = 0;
+ pm->ngamma_tests = 0;
+ pm->gammas = 0;
+ pm->current_gamma = 0;
+ pm->encodings = 0;
+ pm->nencodings = 0;
+ pm->current_encoding = 0;
+ pm->encoding_counter = 0;
+ pm->encoding_ignored = 0;
+ pm->repeat = 0;
+ pm->test_uses_encoding = 0;
+ pm->maxout8 = pm->maxpc8 = pm->maxabs8 = pm->maxcalc8 = 0;
+ pm->maxout16 = pm->maxpc16 = pm->maxabs16 = pm->maxcalc16 = 0;
+ pm->maxcalcG = 0;
+ pm->limit = 4E-3;
+ pm->log8 = pm->log16 = 0; /* Means 'off' */
+ pm->error_gray_2 = pm->error_gray_4 = pm->error_gray_8 = 0;
+ pm->error_gray_16 = pm->error_color_8 = pm->error_color_16 = 0;
+ pm->error_indexed = 0;
+ pm->use_update_info = 0;
+ pm->interlace_type = PNG_INTERLACE_NONE;
+ pm->test_standard = 0;
+ pm->test_size = 0;
+ pm->test_transform = 0;
+# ifdef PNG_WRITE_tRNS_SUPPORTED
+ pm->test_tRNS = 1;
+# else
+ pm->test_tRNS = 0;
+# endif
+ pm->use_input_precision = 0;
+ pm->use_input_precision_sbit = 0;
+ pm->use_input_precision_16to8 = 0;
+ pm->calculations_use_input_precision = 0;
+ pm->assume_16_bit_calculations = 0;
+ pm->test_gamma_threshold = 0;
+ pm->test_gamma_transform = 0;
+ pm->test_gamma_sbit = 0;
+ pm->test_gamma_scale16 = 0;
+ pm->test_gamma_background = 0;
+ pm->test_gamma_alpha_mode = 0;
+ pm->test_gamma_expand16 = 0;
+ pm->test_lbg = 1;
+ pm->test_lbg_gamma_threshold = 1;
+ pm->test_lbg_gamma_transform = 1;
+ pm->test_lbg_gamma_sbit = 1;
+ pm->test_lbg_gamma_composition = 1;
+ pm->test_exhaustive = 0;
+ pm->log = 0;
+
+ /* Rely on the memset for all the other fields - there are no pointers */
+}
+
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
+
+/* This controls use of checks that explicitly know how libpng digitizes the
+ * samples in calculations; setting this circumvents simple error limit checking
+ * in the rgb_to_gray check, replacing it with an exact copy of the libpng 1.5
+ * algorithm.
+ */
+#define DIGITIZE PNG_LIBPNG_VER < 10700
+
+/* If pm->calculations_use_input_precision is set then operations will happen
+ * with the precision of the input, not the precision of the output depth.
+ *
+ * If pm->assume_16_bit_calculations is set then even 8 bit calculations use 16
+ * bit precision. This only affects those of the following limits that pertain
+ * to a calculation - not a digitization operation - unless the following API is
+ * called directly.
+ */
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+#if DIGITIZE
+static double digitize(double value, int depth, int do_round)
+{
+ /* 'value' is in the range 0 to 1, the result is the same value rounded to a
+ * multiple of the digitization factor - 8 or 16 bits depending on both the
+ * sample depth and the 'assume' setting. Digitization is normally by
+ * rounding and 'do_round' should be 1, if it is 0 the digitized value will
+ * be truncated.
+ */
+ const unsigned int digitization_factor = (1U << depth) -1;
+
+ /* Limiting the range is done as a convenience to the caller - it's easier to
+ * do it once here than every time at the call site.
+ */
+ if (value <= 0)
+ value = 0;
+
+ else if (value >= 1)
+ value = 1;
+
+ value *= digitization_factor;
+ if (do_round) value += .5;
+ return floor(value)/digitization_factor;
+}
+#endif
+#endif /* RGB_TO_GRAY */
+
+#ifdef PNG_READ_GAMMA_SUPPORTED
+static double abserr(const png_modifier *pm, int in_depth, int out_depth)
+{
+ /* Absolute error permitted in linear values - affected by the bit depth of
+ * the calculations.
+ */
+ if (pm->assume_16_bit_calculations ||
+ (pm->calculations_use_input_precision ? in_depth : out_depth) == 16)
+ return pm->maxabs16;
+ else
+ return pm->maxabs8;
+}
+
+static double calcerr(const png_modifier *pm, int in_depth, int out_depth)
+{
+ /* Error in the linear composition arithmetic - only relevant when
+ * composition actually happens (0 < alpha < 1).
+ */
+ if ((pm->calculations_use_input_precision ? in_depth : out_depth) == 16)
+ return pm->maxcalc16;
+ else if (pm->assume_16_bit_calculations)
+ return pm->maxcalcG;
+ else
+ return pm->maxcalc8;
+}
+
+static double pcerr(const png_modifier *pm, int in_depth, int out_depth)
+{
+ /* Percentage error permitted in the linear values. Note that the specified
+ * value is a percentage but this routine returns a simple number.
+ */
+ if (pm->assume_16_bit_calculations ||
+ (pm->calculations_use_input_precision ? in_depth : out_depth) == 16)
+ return pm->maxpc16 * .01;
+ else
+ return pm->maxpc8 * .01;
+}
+
+/* Output error - the error in the encoded value. This is determined by the
+ * digitization of the output so can be +/-0.5 in the actual output value. In
+ * the expand_16 case with the current code in libpng the expand happens after
+ * all the calculations are done in 8 bit arithmetic, so even though the output
+ * depth is 16 the output error is determined by the 8 bit calculation.
+ *
+ * This limit is not determined by the bit depth of internal calculations.
+ *
+ * The specified parameter does *not* include the base .5 digitization error but
+ * it is added here.
+ */
+static double outerr(const png_modifier *pm, int in_depth, int out_depth)
+{
+ /* There is a serious error in the 2 and 4 bit grayscale transform because
+ * the gamma table value (8 bits) is simply shifted, not rounded, so the
+ * error in 4 bit grayscale gamma is up to the value below. This is a hack
+ * to allow pngvalid to succeed:
+ *
+ * TODO: fix this in libpng
+ */
+ if (out_depth == 2)
+ return .73182-.5;
+
+ if (out_depth == 4)
+ return .90644-.5;
+
+ if ((pm->calculations_use_input_precision ? in_depth : out_depth) == 16)
+ return pm->maxout16;
+
+ /* This is the case where the value was calculated at 8-bit precision then
+ * scaled to 16 bits.
+ */
+ else if (out_depth == 16)
+ return pm->maxout8 * 257;
+
+ else
+ return pm->maxout8;
+}
+
+/* This does the same thing as the above however it returns the value to log,
+ * rather than raising a warning. This is useful for debugging to track down
+ * exactly what set of parameters cause high error values.
+ */
+static double outlog(const png_modifier *pm, int in_depth, int out_depth)
+{
+ /* The command line parameters are either 8 bit (0..255) or 16 bit (0..65535)
+ * and so must be adjusted for low bit depth grayscale:
+ */
+ if (out_depth <= 8)
+ {
+ if (pm->log8 == 0) /* switched off */
+ return 256;
+
+ if (out_depth < 8)
+ return pm->log8 / 255 * ((1<<out_depth)-1);
+
+ return pm->log8;
+ }
+
+ if ((pm->calculations_use_input_precision ? in_depth : out_depth) == 16)
+ {
+ if (pm->log16 == 0)
+ return 65536;
+
+ return pm->log16;
+ }
+
+ /* This is the case where the value was calculated at 8-bit precision then
+ * scaled to 16 bits.
+ */
+ if (pm->log8 == 0)
+ return 65536;
+
+ return pm->log8 * 257;
+}
+
+/* This complements the above by providing the appropriate quantization for the
+ * final value. Normally this would just be quantization to an integral value,
+ * but in the 8 bit calculation case it's actually quantization to a multiple of
+ * 257!
+ */
+static int output_quantization_factor(const png_modifier *pm, int in_depth,
+ int out_depth)
+{
+ if (out_depth == 16 && in_depth != 16 &&
+ pm->calculations_use_input_precision)
+ return 257;
+ else
+ return 1;
+}
+#endif /* PNG_READ_GAMMA_SUPPORTED */
+
+/* One modification structure must be provided for each chunk to be modified (in
+ * fact more than one can be provided if multiple separate changes are desired
+ * for a single chunk.) Modifications include adding a new chunk when a
+ * suitable chunk does not exist.
+ *
+ * The caller of modify_fn will reset the CRC of the chunk and record 'modified'
+ * or 'added' as appropriate if the modify_fn returns 1 (true). If the
+ * modify_fn is NULL the chunk is simply removed.
+ */
+typedef struct png_modification
+{
+ struct png_modification *next;
+ png_uint_32 chunk;
+
+ /* If the following is NULL all matching chunks will be removed: */
+ int (*modify_fn)(struct png_modifier *pm,
+ struct png_modification *me, int add);
+
+ /* If the following is set to PLTE, IDAT or IEND and the chunk has not been
+ * found and modified (and there is a modify_fn) the modify_fn will be called
+ * to add the chunk before the relevant chunk.
+ */
+ png_uint_32 add;
+ unsigned int modified :1; /* Chunk was modified */
+ unsigned int added :1; /* Chunk was added */
+ unsigned int removed :1; /* Chunk was removed */
+} png_modification;
+
+static void
+modification_reset(png_modification *pmm)
+{
+ if (pmm != NULL)
+ {
+ pmm->modified = 0;
+ pmm->added = 0;
+ pmm->removed = 0;
+ modification_reset(pmm->next);
+ }
+}
+
+static void
+modification_init(png_modification *pmm)
+{
+ memset(pmm, 0, sizeof *pmm);
+ pmm->next = NULL;
+ pmm->chunk = 0;
+ pmm->modify_fn = NULL;
+ pmm->add = 0;
+ modification_reset(pmm);
+}
+
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+static void
+modifier_current_encoding(const png_modifier *pm, color_encoding *ce)
+{
+ if (pm->current_encoding != 0)
+ *ce = *pm->current_encoding;
+
+ else
+ memset(ce, 0, sizeof *ce);
+
+ ce->gamma = pm->current_gamma;
+}
+#endif
+
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
+static size_t
+safecat_current_encoding(char *buffer, size_t bufsize, size_t pos,
+ const png_modifier *pm)
+{
+ pos = safecat_color_encoding(buffer, bufsize, pos, pm->current_encoding,
+ pm->current_gamma);
+
+ if (pm->encoding_ignored)
+ pos = safecat(buffer, bufsize, pos, "[overridden]");
+
+ return pos;
+}
+#endif
+
+/* Iterate through the usefully testable color encodings. An encoding is one
+ * of:
+ *
+ * 1) Nothing (no color space, no gamma).
+ * 2) Just a gamma value from the gamma array (including 1.0)
+ * 3) A color space from the encodings array with the corresponding gamma.
+ * 4) The same, but with gamma 1.0 (only really useful with 16 bit calculations)
+ *
+ * The iterator selects these in turn, the randomizer selects one at random,
+ * which is used depends on the setting of the 'test_exhaustive' flag. Notice
+ * that this function changes the colour space encoding so it must only be
+ * called on completion of the previous test. This is what 'modifier_reset'
+ * does, below.
+ *
+ * After the function has been called the 'repeat' flag will still be set; the
+ * caller of modifier_reset must reset it at the start of each run of the test!
+ */
+static unsigned int
+modifier_total_encodings(const png_modifier *pm)
+{
+ return 1 + /* (1) nothing */
+ pm->ngammas + /* (2) gamma values to test */
+ pm->nencodings + /* (3) total number of encodings */
+ /* The following test only works after the first time through the
+ * png_modifier code because 'bit_depth' is set when the IHDR is read.
+ * modifier_reset, below, preserves the setting until after it has called
+ * the iterate function (also below.)
+ *
+ * For this reason do not rely on this function outside a call to
+ * modifier_reset.
+ */
+ ((pm->bit_depth == 16 || pm->assume_16_bit_calculations) ?
+ pm->nencodings : 0); /* (4) encodings with gamma == 1.0 */
+}
+
+static void
+modifier_encoding_iterate(png_modifier *pm)
+{
+ if (!pm->repeat && /* Else something needs the current encoding again. */
+ pm->test_uses_encoding) /* Some transform is encoding dependent */
+ {
+ if (pm->test_exhaustive)
+ {
+ if (++pm->encoding_counter >= modifier_total_encodings(pm))
+ pm->encoding_counter = 0; /* This will stop the repeat */
+ }
+
+ else
+ {
+ /* Not exhaustive - choose an encoding at random; generate a number in
+ * the range 1..(max-1), so the result is always non-zero:
+ */
+ if (pm->encoding_counter == 0)
+ pm->encoding_counter = random_mod(modifier_total_encodings(pm)-1)+1;
+ else
+ pm->encoding_counter = 0;
+ }
+
+ if (pm->encoding_counter > 0)
+ pm->repeat = 1;
+ }
+
+ else if (!pm->repeat)
+ pm->encoding_counter = 0;
+}
+
+static void
+modifier_reset(png_modifier *pm)
+{
+ store_read_reset(&pm->this);
+ pm->limit = 4E-3;
+ pm->pending_len = pm->pending_chunk = 0;
+ pm->flush = pm->buffer_count = pm->buffer_position = 0;
+ pm->modifications = NULL;
+ pm->state = modifier_start;
+ modifier_encoding_iterate(pm);
+ /* The following must be set in the next run. In particular
+ * test_uses_encodings must be set in the _ini function of each transform
+ * that looks at the encodings. (Not the 'add' function!)
+ */
+ pm->test_uses_encoding = 0;
+ pm->current_gamma = 0;
+ pm->current_encoding = 0;
+ pm->encoding_ignored = 0;
+ /* These only become value after IHDR is read: */
+ pm->bit_depth = pm->colour_type = 0;
+}
+
+/* The following must be called before anything else to get the encoding set up
+ * on the modifier. In particular it must be called before the transform init
+ * functions are called.
+ */
+static void
+modifier_set_encoding(png_modifier *pm)
+{
+ /* Set the encoding to the one specified by the current encoding counter,
+ * first clear out all the settings - this corresponds to an encoding_counter
+ * of 0.
+ */
+ pm->current_gamma = 0;
+ pm->current_encoding = 0;
+ pm->encoding_ignored = 0; /* not ignored yet - happens in _ini functions. */
+
+ /* Now, if required, set the gamma and encoding fields. */
+ if (pm->encoding_counter > 0)
+ {
+ /* The gammas[] array is an array of screen gammas, not encoding gammas,
+ * so we need the inverse:
+ */
+ if (pm->encoding_counter <= pm->ngammas)
+ pm->current_gamma = 1/pm->gammas[pm->encoding_counter-1];
+
+ else
+ {
+ unsigned int i = pm->encoding_counter - pm->ngammas;
+
+ if (i >= pm->nencodings)
+ {
+ i %= pm->nencodings;
+ pm->current_gamma = 1; /* Linear, only in the 16 bit case */
+ }
+
+ else
+ pm->current_gamma = pm->encodings[i].gamma;
+
+ pm->current_encoding = pm->encodings + i;
+ }
+ }
+}
+
+/* Enquiry functions to find out what is set. Notice that there is an implicit
+ * assumption below that the first encoding in the list is the one for sRGB.
+ */
+static int
+modifier_color_encoding_is_sRGB(const png_modifier *pm)
+{
+ return pm->current_encoding != 0 && pm->current_encoding == pm->encodings &&
+ pm->current_encoding->gamma == pm->current_gamma;
+}
+
+static int
+modifier_color_encoding_is_set(const png_modifier *pm)
+{
+ return pm->current_gamma != 0;
+}
+
+/* Convenience macros. */
+#define CHUNK(a,b,c,d) (((a)<<24)+((b)<<16)+((c)<<8)+(d))
+#define CHUNK_IHDR CHUNK(73,72,68,82)
+#define CHUNK_PLTE CHUNK(80,76,84,69)
+#define CHUNK_IDAT CHUNK(73,68,65,84)
+#define CHUNK_IEND CHUNK(73,69,78,68)
+#define CHUNK_cHRM CHUNK(99,72,82,77)
+#define CHUNK_gAMA CHUNK(103,65,77,65)
+#define CHUNK_sBIT CHUNK(115,66,73,84)
+#define CHUNK_sRGB CHUNK(115,82,71,66)
+
+/* The guts of modification are performed during a read. */
+static void
+modifier_crc(png_bytep buffer)
+{
+ /* Recalculate the chunk CRC - a complete chunk must be in
+ * the buffer, at the start.
+ */
+ uInt datalen = png_get_uint_32(buffer);
+ uLong crc = crc32(0, buffer+4, datalen+4);
+ /* The cast to png_uint_32 is safe because a crc32 is always a 32 bit value.
+ */
+ png_save_uint_32(buffer+datalen+8, (png_uint_32)crc);
+}
+
+static void
+modifier_setbuffer(png_modifier *pm)
+{
+ modifier_crc(pm->buffer);
+ pm->buffer_count = png_get_uint_32(pm->buffer)+12;
+ pm->buffer_position = 0;
+}
+
+/* Separate the callback into the actual implementation (which is passed the
+ * png_modifier explicitly) and the callback, which gets the modifier from the
+ * png_struct.
+ */
+static void
+modifier_read_imp(png_modifier *pm, png_bytep pb, png_size_t st)
+{
+ while (st > 0)
+ {
+ size_t cb;
+ png_uint_32 len, chunk;
+ png_modification *mod;
+
+ if (pm->buffer_position >= pm->buffer_count) switch (pm->state)
+ {
+ static png_byte sign[8] = { 137, 80, 78, 71, 13, 10, 26, 10 };
+ case modifier_start:
+ store_read_imp(&pm->this, pm->buffer, 8); /* size of signature. */
+ pm->buffer_count = 8;
+ pm->buffer_position = 0;
+
+ if (memcmp(pm->buffer, sign, 8) != 0)
+ png_error(pm->this.pread, "invalid PNG file signature");
+ pm->state = modifier_signature;
+ break;
+
+ case modifier_signature:
+ store_read_imp(&pm->this, pm->buffer, 13+12); /* size of IHDR */
+ pm->buffer_count = 13+12;
+ pm->buffer_position = 0;
+
+ if (png_get_uint_32(pm->buffer) != 13 ||
+ png_get_uint_32(pm->buffer+4) != CHUNK_IHDR)
+ png_error(pm->this.pread, "invalid IHDR");
+
+ /* Check the list of modifiers for modifications to the IHDR. */
+ mod = pm->modifications;
+ while (mod != NULL)
+ {
+ if (mod->chunk == CHUNK_IHDR && mod->modify_fn &&
+ (*mod->modify_fn)(pm, mod, 0))
+ {
+ mod->modified = 1;
+ modifier_setbuffer(pm);
+ }
+
+ /* Ignore removal or add if IHDR! */
+ mod = mod->next;
+ }
+
+ /* Cache information from the IHDR (the modified one.) */
+ pm->bit_depth = pm->buffer[8+8];
+ pm->colour_type = pm->buffer[8+8+1];
+
+ pm->state = modifier_IHDR;
+ pm->flush = 0;
+ break;
+
+ case modifier_IHDR:
+ default:
+ /* Read a new chunk and process it until we see PLTE, IDAT or
+ * IEND. 'flush' indicates that there is still some data to
+ * output from the preceding chunk.
+ */
+ if ((cb = pm->flush) > 0)
+ {
+ if (cb > st) cb = st;
+ pm->flush -= cb;
+ store_read_imp(&pm->this, pb, cb);
+ pb += cb;
+ st -= cb;
+ if (st == 0) return;
+ }
+
+ /* No more bytes to flush, read a header, or handle a pending
+ * chunk.
+ */
+ if (pm->pending_chunk != 0)
+ {
+ png_save_uint_32(pm->buffer, pm->pending_len);
+ png_save_uint_32(pm->buffer+4, pm->pending_chunk);
+ pm->pending_len = 0;
+ pm->pending_chunk = 0;
+ }
+ else
+ store_read_imp(&pm->this, pm->buffer, 8);
+
+ pm->buffer_count = 8;
+ pm->buffer_position = 0;
+
+ /* Check for something to modify or a terminator chunk. */
+ len = png_get_uint_32(pm->buffer);
+ chunk = png_get_uint_32(pm->buffer+4);
+
+ /* Terminators first, they may have to be delayed for added
+ * chunks
+ */
+ if (chunk == CHUNK_PLTE || chunk == CHUNK_IDAT ||
+ chunk == CHUNK_IEND)
+ {
+ mod = pm->modifications;
+
+ while (mod != NULL)
+ {
+ if ((mod->add == chunk ||
+ (mod->add == CHUNK_PLTE && chunk == CHUNK_IDAT)) &&
+ mod->modify_fn != NULL && !mod->modified && !mod->added)
+ {
+ /* Regardless of what the modify function does do not run
+ * this again.
+ */
+ mod->added = 1;
+
+ if ((*mod->modify_fn)(pm, mod, 1 /*add*/))
+ {
+ /* Reset the CRC on a new chunk */
+ if (pm->buffer_count > 0)
+ modifier_setbuffer(pm);
+
+ else
+ {
+ pm->buffer_position = 0;
+ mod->removed = 1;
+ }
+
+ /* The buffer has been filled with something (we assume)
+ * so output this. Pend the current chunk.
+ */
+ pm->pending_len = len;
+ pm->pending_chunk = chunk;
+ break; /* out of while */
+ }
+ }
+
+ mod = mod->next;
+ }
+
+ /* Don't do any further processing if the buffer was modified -
+ * otherwise the code will end up modifying a chunk that was
+ * just added.
+ */
+ if (mod != NULL)
+ break; /* out of switch */
+ }
+
+ /* If we get to here then this chunk may need to be modified. To
+ * do this it must be less than 1024 bytes in total size, otherwise
+ * it just gets flushed.
+ */
+ if (len+12 <= sizeof pm->buffer)
+ {
+ store_read_imp(&pm->this, pm->buffer+pm->buffer_count,
+ len+12-pm->buffer_count);
+ pm->buffer_count = len+12;
+
+ /* Check for a modification, else leave it be. */
+ mod = pm->modifications;
+ while (mod != NULL)
+ {
+ if (mod->chunk == chunk)
+ {
+ if (mod->modify_fn == NULL)
+ {
+ /* Remove this chunk */
+ pm->buffer_count = pm->buffer_position = 0;
+ mod->removed = 1;
+ break; /* Terminate the while loop */
+ }
+
+ else if ((*mod->modify_fn)(pm, mod, 0))
+ {
+ mod->modified = 1;
+ /* The chunk may have been removed: */
+ if (pm->buffer_count == 0)
+ {
+ pm->buffer_position = 0;
+ break;
+ }
+ modifier_setbuffer(pm);
+ }
+ }
+
+ mod = mod->next;
+ }
+ }
+
+ else
+ pm->flush = len+12 - pm->buffer_count; /* data + crc */
+
+ /* Take the data from the buffer (if there is any). */
+ break;
+ }
+
+ /* Here to read from the modifier buffer (not directly from
+ * the store, as in the flush case above.)
+ */
+ cb = pm->buffer_count - pm->buffer_position;
+
+ if (cb > st)
+ cb = st;
+
+ memcpy(pb, pm->buffer + pm->buffer_position, cb);
+ st -= cb;
+ pb += cb;
+ pm->buffer_position += cb;
+ }
+}
+
+/* The callback: */
+static void PNGCBAPI
+modifier_read(png_structp ppIn, png_bytep pb, png_size_t st)
+{
+ png_const_structp pp = ppIn;
+ png_modifier *pm = voidcast(png_modifier*, png_get_io_ptr(pp));
+
+ if (pm == NULL || pm->this.pread != pp)
+ png_error(pp, "bad modifier_read call");
+
+ modifier_read_imp(pm, pb, st);
+}
+
+/* Like store_progressive_read but the data is getting changed as we go so we
+ * need a local buffer.
+ */
+static void
+modifier_progressive_read(png_modifier *pm, png_structp pp, png_infop pi)
+{
+ if (pm->this.pread != pp || pm->this.current == NULL ||
+ pm->this.next == NULL)
+ png_error(pp, "store state damaged (progressive)");
+
+ /* This is another Horowitz and Hill random noise generator. In this case
+ * the aim is to stress the progressive reader with truly horrible variable
+ * buffer sizes in the range 1..500, so a sequence of 9 bit random numbers
+ * is generated. We could probably just count from 1 to 32767 and get as
+ * good a result.
+ */
+ for (;;)
+ {
+ static png_uint_32 noise = 1;
+ png_size_t cb, cbAvail;
+ png_byte buffer[512];
+
+ /* Generate 15 more bits of stuff: */
+ noise = (noise << 9) | ((noise ^ (noise >> (9-5))) & 0x1ff);
+ cb = noise & 0x1ff;
+
+ /* Check that this number of bytes are available (in the current buffer.)
+ * (This doesn't quite work - the modifier might delete a chunk; unlikely
+ * but possible, it doesn't happen at present because the modifier only
+ * adds chunks to standard images.)
+ */
+ cbAvail = store_read_buffer_avail(&pm->this);
+ if (pm->buffer_count > pm->buffer_position)
+ cbAvail += pm->buffer_count - pm->buffer_position;
+
+ if (cb > cbAvail)
+ {
+ /* Check for EOF: */
+ if (cbAvail == 0)
+ break;
+
+ cb = cbAvail;
+ }
+
+ modifier_read_imp(pm, buffer, cb);
+ png_process_data(pp, pi, buffer, cb);
+ }
+
+ /* Check the invariants at the end (if this fails it's a problem in this
+ * file!)
+ */
+ if (pm->buffer_count > pm->buffer_position ||
+ pm->this.next != &pm->this.current->data ||
+ pm->this.readpos < pm->this.current->datacount)
+ png_error(pp, "progressive read implementation error");
+}
+
+/* Set up a modifier. */
+static png_structp
+set_modifier_for_read(png_modifier *pm, png_infopp ppi, png_uint_32 id,
+ const char *name)
+{
+ /* Do this first so that the modifier fields are cleared even if an error
+ * happens allocating the png_struct. No allocation is done here so no
+ * cleanup is required.
+ */
+ pm->state = modifier_start;
+ pm->bit_depth = 0;
+ pm->colour_type = 255;
+
+ pm->pending_len = 0;
+ pm->pending_chunk = 0;
+ pm->flush = 0;
+ pm->buffer_count = 0;
+ pm->buffer_position = 0;
+
+ return set_store_for_read(&pm->this, ppi, id, name);
+}
+
+
+/******************************** MODIFICATIONS *******************************/
+/* Standard modifications to add chunks. These do not require the _SUPPORTED
+ * macros because the chunks can be there regardless of whether this specific
+ * libpng supports them.
+ */
+typedef struct gama_modification
+{
+ png_modification this;
+ png_fixed_point gamma;
+} gama_modification;
+
+static int
+gama_modify(png_modifier *pm, png_modification *me, int add)
+{
+ UNUSED(add)
+ /* This simply dumps the given gamma value into the buffer. */
+ png_save_uint_32(pm->buffer, 4);
+ png_save_uint_32(pm->buffer+4, CHUNK_gAMA);
+ png_save_uint_32(pm->buffer+8, ((gama_modification*)me)->gamma);
+ return 1;
+}
+
+static void
+gama_modification_init(gama_modification *me, png_modifier *pm, double gammad)
+{
+ double g;
+
+ modification_init(&me->this);
+ me->this.chunk = CHUNK_gAMA;
+ me->this.modify_fn = gama_modify;
+ me->this.add = CHUNK_PLTE;
+ g = fix(gammad);
+ me->gamma = (png_fixed_point)g;
+ me->this.next = pm->modifications;
+ pm->modifications = &me->this;
+}
+
+typedef struct chrm_modification
+{
+ png_modification this;
+ const color_encoding *encoding;
+ png_fixed_point wx, wy, rx, ry, gx, gy, bx, by;
+} chrm_modification;
+
+static int
+chrm_modify(png_modifier *pm, png_modification *me, int add)
+{
+ UNUSED(add)
+ /* As with gAMA this just adds the required cHRM chunk to the buffer. */
+ png_save_uint_32(pm->buffer , 32);
+ png_save_uint_32(pm->buffer+ 4, CHUNK_cHRM);
+ png_save_uint_32(pm->buffer+ 8, ((chrm_modification*)me)->wx);
+ png_save_uint_32(pm->buffer+12, ((chrm_modification*)me)->wy);
+ png_save_uint_32(pm->buffer+16, ((chrm_modification*)me)->rx);
+ png_save_uint_32(pm->buffer+20, ((chrm_modification*)me)->ry);
+ png_save_uint_32(pm->buffer+24, ((chrm_modification*)me)->gx);
+ png_save_uint_32(pm->buffer+28, ((chrm_modification*)me)->gy);
+ png_save_uint_32(pm->buffer+32, ((chrm_modification*)me)->bx);
+ png_save_uint_32(pm->buffer+36, ((chrm_modification*)me)->by);
+ return 1;
+}
+
+static void
+chrm_modification_init(chrm_modification *me, png_modifier *pm,
+ const color_encoding *encoding)
+{
+ CIE_color white = white_point(encoding);
+
+ /* Original end points: */
+ me->encoding = encoding;
+
+ /* Chromaticities (in fixed point): */
+ me->wx = fix(chromaticity_x(white));
+ me->wy = fix(chromaticity_y(white));
+
+ me->rx = fix(chromaticity_x(encoding->red));
+ me->ry = fix(chromaticity_y(encoding->red));
+ me->gx = fix(chromaticity_x(encoding->green));
+ me->gy = fix(chromaticity_y(encoding->green));
+ me->bx = fix(chromaticity_x(encoding->blue));
+ me->by = fix(chromaticity_y(encoding->blue));
+
+ modification_init(&me->this);
+ me->this.chunk = CHUNK_cHRM;
+ me->this.modify_fn = chrm_modify;
+ me->this.add = CHUNK_PLTE;
+ me->this.next = pm->modifications;
+ pm->modifications = &me->this;
+}
+
+typedef struct srgb_modification
+{
+ png_modification this;
+ png_byte intent;
+} srgb_modification;
+
+static int
+srgb_modify(png_modifier *pm, png_modification *me, int add)
+{
+ UNUSED(add)
+ /* As above, ignore add and just make a new chunk */
+ png_save_uint_32(pm->buffer, 1);
+ png_save_uint_32(pm->buffer+4, CHUNK_sRGB);
+ pm->buffer[8] = ((srgb_modification*)me)->intent;
+ return 1;
+}
+
+static void
+srgb_modification_init(srgb_modification *me, png_modifier *pm, png_byte intent)
+{
+ modification_init(&me->this);
+ me->this.chunk = CHUNK_sBIT;
+
+ if (intent <= 3) /* if valid, else *delete* sRGB chunks */
+ {
+ me->this.modify_fn = srgb_modify;
+ me->this.add = CHUNK_PLTE;
+ me->intent = intent;
+ }
+
+ else
+ {
+ me->this.modify_fn = 0;
+ me->this.add = 0;
+ me->intent = 0;
+ }
+
+ me->this.next = pm->modifications;
+ pm->modifications = &me->this;
+}
+
+#ifdef PNG_READ_GAMMA_SUPPORTED
+typedef struct sbit_modification
+{
+ png_modification this;
+ png_byte sbit;
+} sbit_modification;
+
+static int
+sbit_modify(png_modifier *pm, png_modification *me, int add)
+{
+ png_byte sbit = ((sbit_modification*)me)->sbit;
+ if (pm->bit_depth > sbit)
+ {
+ int cb = 0;
+ switch (pm->colour_type)
+ {
+ case 0:
+ cb = 1;
+ break;
+
+ case 2:
+ case 3:
+ cb = 3;
+ break;
+
+ case 4:
+ cb = 2;
+ break;
+
+ case 6:
+ cb = 4;
+ break;
+
+ default:
+ png_error(pm->this.pread,
+ "unexpected colour type in sBIT modification");
+ }
+
+ png_save_uint_32(pm->buffer, cb);
+ png_save_uint_32(pm->buffer+4, CHUNK_sBIT);
+
+ while (cb > 0)
+ (pm->buffer+8)[--cb] = sbit;
+
+ return 1;
+ }
+ else if (!add)
+ {
+ /* Remove the sBIT chunk */
+ pm->buffer_count = pm->buffer_position = 0;
+ return 1;
+ }
+ else
+ return 0; /* do nothing */
+}
+
+static void
+sbit_modification_init(sbit_modification *me, png_modifier *pm, png_byte sbit)
+{
+ modification_init(&me->this);
+ me->this.chunk = CHUNK_sBIT;
+ me->this.modify_fn = sbit_modify;
+ me->this.add = CHUNK_PLTE;
+ me->sbit = sbit;
+ me->this.next = pm->modifications;
+ pm->modifications = &me->this;
+}
+#endif /* PNG_READ_GAMMA_SUPPORTED */
+#endif /* PNG_READ_TRANSFORMS_SUPPORTED */
+
+/***************************** STANDARD PNG FILES *****************************/
+/* Standard files - write and save standard files. */
+/* There are two basic forms of standard images. Those which attempt to have
+ * all the possible pixel values (not possible for 16bpp images, but a range of
+ * values are produced) and those which have a range of image sizes. The former
+ * are used for testing transforms, in particular gamma correction and bit
+ * reduction and increase. The latter are reserved for testing the behavior of
+ * libpng with respect to 'odd' image sizes - particularly small images where
+ * rows become 1 byte and interlace passes disappear.
+ *
+ * The first, most useful, set are the 'transform' images, the second set of
+ * small images are the 'size' images.
+ *
+ * The transform files are constructed with rows which fit into a 1024 byte row
+ * buffer. This makes allocation easier below. Further regardless of the file
+ * format every row has 128 pixels (giving 1024 bytes for 64bpp formats).
+ *
+ * Files are stored with no gAMA or sBIT chunks, with a PLTE only when needed
+ * and with an ID derived from the colour type, bit depth and interlace type
+ * as above (FILEID). The width (128) and height (variable) are not stored in
+ * the FILEID - instead the fields are set to 0, indicating a transform file.
+ *
+ * The size files ar constructed with rows a maximum of 128 bytes wide, allowing
+ * a maximum width of 16 pixels (for the 64bpp case.) They also have a maximum
+ * height of 16 rows. The width and height are stored in the FILEID and, being
+ * non-zero, indicate a size file.
+ *
+ * Because the PNG filter code is typically the largest CPU consumer within
+ * libpng itself there is a tendency to attempt to optimize it. This results in
+ * special case code which needs to be validated. To cause this to happen the
+ * 'size' images are made to use each possible filter, in so far as this is
+ * possible for smaller images.
+ *
+ * For palette image (colour type 3) multiple transform images are stored with
+ * the same bit depth to allow testing of more colour combinations -
+ * particularly important for testing the gamma code because libpng uses a
+ * different code path for palette images. For size images a single palette is
+ * used.
+ */
+
+/* Make a 'standard' palette. Because there are only 256 entries in a palette
+ * (maximum) this actually makes a random palette in the hope that enough tests
+ * will catch enough errors. (Note that the same palette isn't produced every
+ * time for the same test - it depends on what previous tests have been run -
+ * but a given set of arguments to pngvalid will always produce the same palette
+ * at the same test! This is why pseudo-random number generators are useful for
+ * testing.)
+ *
+ * The store must be open for write when this is called, otherwise an internal
+ * error will occur. This routine contains its own magic number seed, so the
+ * palettes generated don't change if there are intervening errors (changing the
+ * calls to the store_mark seed.)
+ */
+static store_palette_entry *
+make_standard_palette(png_store* ps, int npalette, int do_tRNS)
+{
+ static png_uint_32 palette_seed[2] = { 0x87654321, 9 };
+
+ int i = 0;
+ png_byte values[256][4];
+
+ /* Always put in black and white plus the six primary and secondary colors.
+ */
+ for (; i<8; ++i)
+ {
+ values[i][1] = (png_byte)((i&1) ? 255U : 0U);
+ values[i][2] = (png_byte)((i&2) ? 255U : 0U);
+ values[i][3] = (png_byte)((i&4) ? 255U : 0U);
+ }
+
+ /* Then add 62 grays (one quarter of the remaining 256 slots). */
+ {
+ int j = 0;
+ png_byte random_bytes[4];
+ png_byte need[256];
+
+ need[0] = 0; /*got black*/
+ memset(need+1, 1, (sizeof need)-2); /*need these*/
+ need[255] = 0; /*but not white*/
+
+ while (i<70)
+ {
+ png_byte b;
+
+ if (j==0)
+ {
+ make_four_random_bytes(palette_seed, random_bytes);
+ j = 4;
+ }
+
+ b = random_bytes[--j];
+ if (need[b])
+ {
+ values[i][1] = b;
+ values[i][2] = b;
+ values[i++][3] = b;
+ }
+ }
+ }
+
+ /* Finally add 192 colors at random - don't worry about matches to things we
+ * already have, chance is less than 1/65536. Don't worry about grays,
+ * chance is the same, so we get a duplicate or extra gray less than 1 time
+ * in 170.
+ */
+ for (; i<256; ++i)
+ make_four_random_bytes(palette_seed, values[i]);
+
+ /* Fill in the alpha values in the first byte. Just use all possible values
+ * (0..255) in an apparently random order:
+ */
+ {
+ store_palette_entry *palette;
+ png_byte selector[4];
+
+ make_four_random_bytes(palette_seed, selector);
+
+ if (do_tRNS)
+ for (i=0; i<256; ++i)
+ values[i][0] = (png_byte)(i ^ selector[0]);
+
+ else
+ for (i=0; i<256; ++i)
+ values[i][0] = 255; /* no transparency/tRNS chunk */
+
+ /* 'values' contains 256 ARGB values, but we only need 'npalette'.
+ * 'npalette' will always be a power of 2: 2, 4, 16 or 256. In the low
+ * bit depth cases select colors at random, else it is difficult to have
+ * a set of low bit depth palette test with any chance of a reasonable
+ * range of colors. Do this by randomly permuting values into the low
+ * 'npalette' entries using an XOR mask generated here. This also
+ * permutes the npalette == 256 case in a potentially useful way (there is
+ * no relationship between palette index and the color value therein!)
+ */
+ palette = store_write_palette(ps, npalette);
+
+ for (i=0; i<npalette; ++i)
+ {
+ palette[i].alpha = values[i ^ selector[1]][0];
+ palette[i].red = values[i ^ selector[1]][1];
+ palette[i].green = values[i ^ selector[1]][2];
+ palette[i].blue = values[i ^ selector[1]][3];
+ }
+
+ return palette;
+ }
+}
+
+/* Initialize a standard palette on a write stream. The 'do_tRNS' argument
+ * indicates whether or not to also set the tRNS chunk.
+ */
+/* TODO: the png_structp here can probably be 'const' in the future */
+static void
+init_standard_palette(png_store *ps, png_structp pp, png_infop pi, int npalette,
+ int do_tRNS)
+{
+ store_palette_entry *ppal = make_standard_palette(ps, npalette, do_tRNS);
+
+ {
+ int i;
+ png_color palette[256];
+
+ /* Set all entries to detect overread errors. */
+ for (i=0; i<npalette; ++i)
+ {
+ palette[i].red = ppal[i].red;
+ palette[i].green = ppal[i].green;
+ palette[i].blue = ppal[i].blue;
+ }
+
+ /* Just in case fill in the rest with detectable values: */
+ for (; i<256; ++i)
+ palette[i].red = palette[i].green = palette[i].blue = 42;
+
+ png_set_PLTE(pp, pi, palette, npalette);
+ }
+
+ if (do_tRNS)
+ {
+ int i, j;
+ png_byte tRNS[256];
+
+ /* Set all the entries, but skip trailing opaque entries */
+ for (i=j=0; i<npalette; ++i)
+ if ((tRNS[i] = ppal[i].alpha) < 255)
+ j = i+1;
+
+ /* Fill in the remainder with a detectable value: */
+ for (; i<256; ++i)
+ tRNS[i] = 24;
+
+# ifdef PNG_WRITE_tRNS_SUPPORTED
+ if (j > 0)
+ png_set_tRNS(pp, pi, tRNS, j, 0/*color*/);
+# endif
+ }
+}
+
+#ifdef PNG_WRITE_tRNS_SUPPORTED
+static void
+set_random_tRNS(png_structp pp, png_infop pi, const png_byte colour_type,
+ const int bit_depth)
+{
+ /* To make this useful the tRNS color needs to match at least one pixel.
+ * Random values are fine for gray, including the 16-bit case where we know
+ * that the test image contains all the gray values. For RGB we need more
+ * method as only 65536 different RGB values are generated.
+ */
+ png_color_16 tRNS;
+ const png_uint_16 mask = (png_uint_16)((1U << bit_depth)-1);
+
+ RANDOMIZE(tRNS);
+
+ if (colour_type & 2/*RGB*/)
+ {
+ if (bit_depth == 8)
+ {
+ tRNS.blue = tRNS.red ^ tRNS.green;
+ tRNS.red &= mask;
+ tRNS.green &= mask;
+ tRNS.blue &= mask;
+ }
+
+ else /* bit_depth == 16 */
+ {
+ tRNS.green = (png_uint_16)(tRNS.red * 257);
+ tRNS.blue = (png_uint_16)(tRNS.green * 17);
+ }
+ }
+
+ else
+ tRNS.gray &= mask;
+
+ png_set_tRNS(pp, pi, NULL, 0, &tRNS);
+}
+#endif
+
+/* The number of passes is related to the interlace type. There was no libpng
+ * API to determine this prior to 1.5, so we need an inquiry function:
+ */
+static int
+npasses_from_interlace_type(png_const_structp pp, int interlace_type)
+{
+ switch (interlace_type)
+ {
+ default:
+ png_error(pp, "invalid interlace type");
+
+ case PNG_INTERLACE_NONE:
+ return 1;
+
+ case PNG_INTERLACE_ADAM7:
+ return PNG_INTERLACE_ADAM7_PASSES;
+ }
+}
+
+static unsigned int
+bit_size(png_const_structp pp, png_byte colour_type, png_byte bit_depth)
+{
+ switch (colour_type)
+ {
+ default: png_error(pp, "invalid color type");
+
+ case 0: return bit_depth;
+
+ case 2: return 3*bit_depth;
+
+ case 3: return bit_depth;
+
+ case 4: return 2*bit_depth;
+
+ case 6: return 4*bit_depth;
+ }
+}
+
+#define TRANSFORM_WIDTH 128U
+#define TRANSFORM_ROWMAX (TRANSFORM_WIDTH*8U)
+#define SIZE_ROWMAX (16*8U) /* 16 pixels, max 8 bytes each - 128 bytes */
+#define STANDARD_ROWMAX TRANSFORM_ROWMAX /* The larger of the two */
+#define SIZE_HEIGHTMAX 16 /* Maximum range of size images */
+
+static size_t
+transform_rowsize(png_const_structp pp, png_byte colour_type,
+ png_byte bit_depth)
+{
+ return (TRANSFORM_WIDTH * bit_size(pp, colour_type, bit_depth)) / 8;
+}
+
+/* transform_width(pp, colour_type, bit_depth) current returns the same number
+ * every time, so just use a macro:
+ */
+#define transform_width(pp, colour_type, bit_depth) TRANSFORM_WIDTH
+
+static png_uint_32
+transform_height(png_const_structp pp, png_byte colour_type, png_byte bit_depth)
+{
+ switch (bit_size(pp, colour_type, bit_depth))
+ {
+ case 1:
+ case 2:
+ case 4:
+ return 1; /* Total of 128 pixels */
+
+ case 8:
+ return 2; /* Total of 256 pixels/bytes */
+
+ case 16:
+ return 512; /* Total of 65536 pixels */
+
+ case 24:
+ case 32:
+ return 512; /* 65536 pixels */
+
+ case 48:
+ case 64:
+ return 2048;/* 4 x 65536 pixels. */
+# define TRANSFORM_HEIGHTMAX 2048
+
+ default:
+ return 0; /* Error, will be caught later */
+ }
+}
+
+#ifdef PNG_READ_SUPPORTED
+/* The following can only be defined here, now we have the definitions
+ * of the transform image sizes.
+ */
+static png_uint_32
+standard_width(png_const_structp pp, png_uint_32 id)
+{
+ png_uint_32 width = WIDTH_FROM_ID(id);
+ UNUSED(pp)
+
+ if (width == 0)
+ width = transform_width(pp, COL_FROM_ID(id), DEPTH_FROM_ID(id));
+
+ return width;
+}
+
+static png_uint_32
+standard_height(png_const_structp pp, png_uint_32 id)
+{
+ png_uint_32 height = HEIGHT_FROM_ID(id);
+
+ if (height == 0)
+ height = transform_height(pp, COL_FROM_ID(id), DEPTH_FROM_ID(id));
+
+ return height;
+}
+
+static png_uint_32
+standard_rowsize(png_const_structp pp, png_uint_32 id)
+{
+ png_uint_32 width = standard_width(pp, id);
+
+ /* This won't overflow: */
+ width *= bit_size(pp, COL_FROM_ID(id), DEPTH_FROM_ID(id));
+ return (width + 7) / 8;
+}
+#endif /* PNG_READ_SUPPORTED */
+
+static void
+transform_row(png_const_structp pp, png_byte buffer[TRANSFORM_ROWMAX],
+ png_byte colour_type, png_byte bit_depth, png_uint_32 y)
+{
+ png_uint_32 v = y << 7;
+ png_uint_32 i = 0;
+
+ switch (bit_size(pp, colour_type, bit_depth))
+ {
+ case 1:
+ while (i<128/8) buffer[i] = (png_byte)(v & 0xff), v += 17, ++i;
+ return;
+
+ case 2:
+ while (i<128/4) buffer[i] = (png_byte)(v & 0xff), v += 33, ++i;
+ return;
+
+ case 4:
+ while (i<128/2) buffer[i] = (png_byte)(v & 0xff), v += 65, ++i;
+ return;
+
+ case 8:
+ /* 256 bytes total, 128 bytes in each row set as follows: */
+ while (i<128) buffer[i] = (png_byte)(v & 0xff), ++v, ++i;
+ return;
+
+ case 16:
+ /* Generate all 65536 pixel values in order, which includes the 8 bit
+ * GA case as well as the 16 bit G case.
+ */
+ while (i<128)
+ {
+ buffer[2*i] = (png_byte)((v>>8) & 0xff);
+ buffer[2*i+1] = (png_byte)(v & 0xff);
+ ++v;
+ ++i;
+ }
+
+ return;
+
+ case 24:
+ /* 65535 pixels, but rotate the values. */
+ while (i<128)
+ {
+ /* Three bytes per pixel, r, g, b, make b by r^g */
+ buffer[3*i+0] = (png_byte)((v >> 8) & 0xff);
+ buffer[3*i+1] = (png_byte)(v & 0xff);
+ buffer[3*i+2] = (png_byte)(((v >> 8) ^ v) & 0xff);
+ ++v;
+ ++i;
+ }
+
+ return;
+
+ case 32:
+ /* 65535 pixels, r, g, b, a; just replicate */
+ while (i<128)
+ {
+ buffer[4*i+0] = (png_byte)((v >> 8) & 0xff);
+ buffer[4*i+1] = (png_byte)(v & 0xff);
+ buffer[4*i+2] = (png_byte)((v >> 8) & 0xff);
+ buffer[4*i+3] = (png_byte)(v & 0xff);
+ ++v;
+ ++i;
+ }
+
+ return;
+
+ case 48:
+ /* y is maximum 2047, giving 4x65536 pixels, make 'r' increase by 1 at
+ * each pixel, g increase by 257 (0x101) and 'b' by 0x1111:
+ */
+ while (i<128)
+ {
+ png_uint_32 t = v++;
+ buffer[6*i+0] = (png_byte)((t >> 8) & 0xff);
+ buffer[6*i+1] = (png_byte)(t & 0xff);
+ t *= 257;
+ buffer[6*i+2] = (png_byte)((t >> 8) & 0xff);
+ buffer[6*i+3] = (png_byte)(t & 0xff);
+ t *= 17;
+ buffer[6*i+4] = (png_byte)((t >> 8) & 0xff);
+ buffer[6*i+5] = (png_byte)(t & 0xff);
+ ++i;
+ }
+
+ return;
+
+ case 64:
+ /* As above in the 32 bit case. */
+ while (i<128)
+ {
+ png_uint_32 t = v++;
+ buffer[8*i+0] = (png_byte)((t >> 8) & 0xff);
+ buffer[8*i+1] = (png_byte)(t & 0xff);
+ buffer[8*i+4] = (png_byte)((t >> 8) & 0xff);
+ buffer[8*i+5] = (png_byte)(t & 0xff);
+ t *= 257;
+ buffer[8*i+2] = (png_byte)((t >> 8) & 0xff);
+ buffer[8*i+3] = (png_byte)(t & 0xff);
+ buffer[8*i+6] = (png_byte)((t >> 8) & 0xff);
+ buffer[8*i+7] = (png_byte)(t & 0xff);
+ ++i;
+ }
+ return;
+
+ default:
+ break;
+ }
+
+ png_error(pp, "internal error");
+}
+
+/* This is just to do the right cast - could be changed to a function to check
+ * 'bd' but there isn't much point.
+ */
+#define DEPTH(bd) ((png_byte)(1U << (bd)))
+
+/* This is just a helper for compiling on minimal systems with no write
+ * interlacing support. If there is no write interlacing we can't generate test
+ * cases with interlace:
+ */
+#ifdef PNG_WRITE_INTERLACING_SUPPORTED
+# define INTERLACE_LAST PNG_INTERLACE_LAST
+# define check_interlace_type(type) ((void)(type))
+# define set_write_interlace_handling(pp,type) png_set_interlace_handling(pp)
+# define do_own_interlace 0
+#elif PNG_LIBPNG_VER < 10700
+# define set_write_interlace_handling(pp,type) (1)
+static void
+check_interlace_type(int const interlace_type)
+{
+ /* Prior to 1.7.0 libpng does not support the write of an interlaced image
+ * unless PNG_WRITE_INTERLACING_SUPPORTED, even with do_interlace so the
+ * code here does the pixel interlace itself, so:
+ */
+ if (interlace_type != PNG_INTERLACE_NONE)
+ {
+ /* This is an internal error - --interlace tests should be skipped, not
+ * attempted.
+ */
+ fprintf(stderr, "pngvalid: no interlace support\n");
+ exit(99);
+ }
+}
+# define INTERLACE_LAST (PNG_INTERLACE_NONE+1)
+# define do_own_interlace 0
+#else /* libpng 1.7+ */
+# define set_write_interlace_handling(pp,type)\
+ npasses_from_interlace_type(pp,type)
+# define check_interlace_type(type) ((void)(type))
+# define INTERLACE_LAST PNG_INTERLACE_LAST
+# define do_own_interlace 1
+#endif /* WRITE_INTERLACING tests */
+
+#define CAN_WRITE_INTERLACE\
+ PNG_LIBPNG_VER >= 10700 || defined PNG_WRITE_INTERLACING_SUPPORTED
+
+/* Do the same thing for read interlacing; this controls whether read tests do
+ * their own de-interlace or use libpng.
+ */
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+# define do_read_interlace 0
+#else /* no libpng read interlace support */
+# define do_read_interlace 1
+#endif
+/* The following two routines use the PNG interlace support macros from
+ * png.h to interlace or deinterlace rows.
+ */
+static void
+interlace_row(png_bytep buffer, png_const_bytep imageRow,
+ unsigned int pixel_size, png_uint_32 w, int pass, int littleendian)
+{
+ png_uint_32 xin, xout, xstep;
+
+ /* Note that this can, trivially, be optimized to a memcpy on pass 7, the
+ * code is presented this way to make it easier to understand. In practice
+ * consult the code in the libpng source to see other ways of doing this.
+ *
+ * It is OK for buffer and imageRow to be identical, because 'xin' moves
+ * faster than 'xout' and we copy up.
+ */
+ xin = PNG_PASS_START_COL(pass);
+ xstep = 1U<<PNG_PASS_COL_SHIFT(pass);
+
+ for (xout=0; xin<w; xin+=xstep)
+ {
+ pixel_copy(buffer, xout, imageRow, xin, pixel_size, littleendian);
+ ++xout;
+ }
+}
+
+#ifdef PNG_READ_SUPPORTED
+static void
+deinterlace_row(png_bytep buffer, png_const_bytep row,
+ unsigned int pixel_size, png_uint_32 w, int pass, int littleendian)
+{
+ /* The inverse of the above, 'row' is part of row 'y' of the output image,
+ * in 'buffer'. The image is 'w' wide and this is pass 'pass', distribute
+ * the pixels of row into buffer and return the number written (to allow
+ * this to be checked).
+ */
+ png_uint_32 xin, xout, xstep;
+
+ xout = PNG_PASS_START_COL(pass);
+ xstep = 1U<<PNG_PASS_COL_SHIFT(pass);
+
+ for (xin=0; xout<w; xout+=xstep)
+ {
+ pixel_copy(buffer, xout, row, xin, pixel_size, littleendian);
+ ++xin;
+ }
+}
+#endif /* PNG_READ_SUPPORTED */
+
+/* Make a standardized image given an image colour type, bit depth and
+ * interlace type. The standard images have a very restricted range of
+ * rows and heights and are used for testing transforms rather than image
+ * layout details. See make_size_images below for a way to make images
+ * that test odd sizes along with the libpng interlace handling.
+ */
+static void
+make_transform_image(png_store* const ps, png_byte const colour_type,
+ png_byte const bit_depth, unsigned int palette_number,
+ int interlace_type, png_const_charp name)
+{
+ context(ps, fault);
+
+ check_interlace_type(interlace_type);
+
+ Try
+ {
+ png_infop pi;
+ png_structp pp = set_store_for_write(ps, &pi, name);
+ png_uint_32 h, w;
+
+ /* In the event of a problem return control to the Catch statement below
+ * to do the clean up - it is not possible to 'return' directly from a Try
+ * block.
+ */
+ if (pp == NULL)
+ Throw ps;
+
+ w = transform_width(pp, colour_type, bit_depth);
+ h = transform_height(pp, colour_type, bit_depth);
+
+ png_set_IHDR(pp, pi, w, h, bit_depth, colour_type, interlace_type,
+ PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+
+#ifdef PNG_TEXT_SUPPORTED
+# if defined(PNG_READ_zTXt_SUPPORTED) && defined(PNG_WRITE_zTXt_SUPPORTED)
+# define TEXT_COMPRESSION PNG_TEXT_COMPRESSION_zTXt
+# else
+# define TEXT_COMPRESSION PNG_TEXT_COMPRESSION_NONE
+# endif
+ {
+ static char key[] = "image name"; /* must be writeable */
+ size_t pos;
+ png_text text;
+ char copy[FILE_NAME_SIZE];
+
+ /* Use a compressed text string to test the correct interaction of text
+ * compression and IDAT compression.
+ */
+ text.compression = TEXT_COMPRESSION;
+ text.key = key;
+ /* Yuck: the text must be writable! */
+ pos = safecat(copy, sizeof copy, 0, ps->wname);
+ text.text = copy;
+ text.text_length = pos;
+ text.itxt_length = 0;
+ text.lang = 0;
+ text.lang_key = 0;
+
+ png_set_text(pp, pi, &text, 1);
+ }
+#endif
+
+ if (colour_type == 3) /* palette */
+ init_standard_palette(ps, pp, pi, 1U << bit_depth, 1/*do tRNS*/);
+
+# ifdef PNG_WRITE_tRNS_SUPPORTED
+ else if (palette_number)
+ set_random_tRNS(pp, pi, colour_type, bit_depth);
+# endif
+
+ png_write_info(pp, pi);
+
+ if (png_get_rowbytes(pp, pi) !=
+ transform_rowsize(pp, colour_type, bit_depth))
+ png_error(pp, "transform row size incorrect");
+
+ else
+ {
+ /* Somewhat confusingly this must be called *after* png_write_info
+ * because if it is called before, the information in *pp has not been
+ * updated to reflect the interlaced image.
+ */
+ int npasses = set_write_interlace_handling(pp, interlace_type);
+ int pass;
+
+ if (npasses != npasses_from_interlace_type(pp, interlace_type))
+ png_error(pp, "write: png_set_interlace_handling failed");
+
+ for (pass=0; pass<npasses; ++pass)
+ {
+ png_uint_32 y;
+
+ /* do_own_interlace is a pre-defined boolean (a #define) which is
+ * set if we have to work out the interlaced rows here.
+ */
+ for (y=0; y<h; ++y)
+ {
+ png_byte buffer[TRANSFORM_ROWMAX];
+
+ transform_row(pp, buffer, colour_type, bit_depth, y);
+
+# if do_own_interlace
+ /* If do_own_interlace *and* the image is interlaced we need a
+ * reduced interlace row; this may be reduced to empty.
+ */
+ if (interlace_type == PNG_INTERLACE_ADAM7)
+ {
+ /* The row must not be written if it doesn't exist, notice
+ * that there are two conditions here, either the row isn't
+ * ever in the pass or the row would be but isn't wide
+ * enough to contribute any pixels. In fact the wPass test
+ * can be used to skip the whole y loop in this case.
+ */
+ if (PNG_ROW_IN_INTERLACE_PASS(y, pass) &&
+ PNG_PASS_COLS(w, pass) > 0)
+ interlace_row(buffer, buffer,
+ bit_size(pp, colour_type, bit_depth), w, pass,
+ 0/*data always bigendian*/);
+ else
+ continue;
+ }
+# endif /* do_own_interlace */
+
+ png_write_row(pp, buffer);
+ }
+ }
+ }
+
+#ifdef PNG_TEXT_SUPPORTED
+ {
+ static char key[] = "end marker";
+ static char comment[] = "end";
+ png_text text;
+
+ /* Use a compressed text string to test the correct interaction of text
+ * compression and IDAT compression.
+ */
+ text.compression = TEXT_COMPRESSION;
+ text.key = key;
+ text.text = comment;
+ text.text_length = (sizeof comment)-1;
+ text.itxt_length = 0;
+ text.lang = 0;
+ text.lang_key = 0;
+
+ png_set_text(pp, pi, &text, 1);
+ }
+#endif
+
+ png_write_end(pp, pi);
+
+ /* And store this under the appropriate id, then clean up. */
+ store_storefile(ps, FILEID(colour_type, bit_depth, palette_number,
+ interlace_type, 0, 0, 0));
+
+ store_write_reset(ps);
+ }
+
+ Catch(fault)
+ {
+ /* Use the png_store returned by the exception. This may help the compiler
+ * because 'ps' is not used in this branch of the setjmp. Note that fault
+ * and ps will always be the same value.
+ */
+ store_write_reset(fault);
+ }
+}
+
+static void
+make_transform_images(png_modifier *pm)
+{
+ png_byte colour_type = 0;
+ png_byte bit_depth = 0;
+ unsigned int palette_number = 0;
+
+ /* This is in case of errors. */
+ safecat(pm->this.test, sizeof pm->this.test, 0, "make standard images");
+
+ /* Use next_format to enumerate all the combinations we test, including
+ * generating multiple low bit depth palette images. Non-A images (palette
+ * and direct) are created with and without tRNS chunks.
+ */
+ while (next_format(&colour_type, &bit_depth, &palette_number, 1, 1))
+ {
+ int interlace_type;
+
+ for (interlace_type = PNG_INTERLACE_NONE;
+ interlace_type < INTERLACE_LAST; ++interlace_type)
+ {
+ char name[FILE_NAME_SIZE];
+
+ standard_name(name, sizeof name, 0, colour_type, bit_depth,
+ palette_number, interlace_type, 0, 0, do_own_interlace);
+ make_transform_image(&pm->this, colour_type, bit_depth, palette_number,
+ interlace_type, name);
+ }
+ }
+}
+
+/* Build a single row for the 'size' test images; this fills in only the
+ * first bit_width bits of the sample row.
+ */
+static void
+size_row(png_byte buffer[SIZE_ROWMAX], png_uint_32 bit_width, png_uint_32 y)
+{
+ /* height is in the range 1 to 16, so: */
+ y = ((y & 1) << 7) + ((y & 2) << 6) + ((y & 4) << 5) + ((y & 8) << 4);
+ /* the following ensures bits are set in small images: */
+ y ^= 0xA5;
+
+ while (bit_width >= 8)
+ *buffer++ = (png_byte)y++, bit_width -= 8;
+
+ /* There may be up to 7 remaining bits, these go in the most significant
+ * bits of the byte.
+ */
+ if (bit_width > 0)
+ {
+ png_uint_32 mask = (1U<<(8-bit_width))-1;
+ *buffer = (png_byte)((*buffer & mask) | (y & ~mask));
+ }
+}
+
+static void
+make_size_image(png_store* const ps, png_byte const colour_type,
+ png_byte const bit_depth, int const interlace_type,
+ png_uint_32 const w, png_uint_32 const h,
+ int const do_interlace)
+{
+ context(ps, fault);
+
+ check_interlace_type(interlace_type);
+
+ Try
+ {
+ png_infop pi;
+ png_structp pp;
+ unsigned int pixel_size;
+
+ /* Make a name and get an appropriate id for the store: */
+ char name[FILE_NAME_SIZE];
+ const png_uint_32 id = FILEID(colour_type, bit_depth, 0/*palette*/,
+ interlace_type, w, h, do_interlace);
+
+ standard_name_from_id(name, sizeof name, 0, id);
+ pp = set_store_for_write(ps, &pi, name);
+
+ /* In the event of a problem return control to the Catch statement below
+ * to do the clean up - it is not possible to 'return' directly from a Try
+ * block.
+ */
+ if (pp == NULL)
+ Throw ps;
+
+ png_set_IHDR(pp, pi, w, h, bit_depth, colour_type, interlace_type,
+ PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+
+#ifdef PNG_TEXT_SUPPORTED
+ {
+ static char key[] = "image name"; /* must be writeable */
+ size_t pos;
+ png_text text;
+ char copy[FILE_NAME_SIZE];
+
+ /* Use a compressed text string to test the correct interaction of text
+ * compression and IDAT compression.
+ */
+ text.compression = TEXT_COMPRESSION;
+ text.key = key;
+ /* Yuck: the text must be writable! */
+ pos = safecat(copy, sizeof copy, 0, ps->wname);
+ text.text = copy;
+ text.text_length = pos;
+ text.itxt_length = 0;
+ text.lang = 0;
+ text.lang_key = 0;
+
+ png_set_text(pp, pi, &text, 1);
+ }
+#endif
+
+ if (colour_type == 3) /* palette */
+ init_standard_palette(ps, pp, pi, 1U << bit_depth, 0/*do tRNS*/);
+
+ png_write_info(pp, pi);
+
+ /* Calculate the bit size, divide by 8 to get the byte size - this won't
+ * overflow because we know the w values are all small enough even for
+ * a system where 'unsigned int' is only 16 bits.
+ */
+ pixel_size = bit_size(pp, colour_type, bit_depth);
+ if (png_get_rowbytes(pp, pi) != ((w * pixel_size) + 7) / 8)
+ png_error(pp, "size row size incorrect");
+
+ else
+ {
+ int npasses = npasses_from_interlace_type(pp, interlace_type);
+ png_uint_32 y;
+ int pass;
+# ifdef PNG_WRITE_FILTER_SUPPORTED
+ int nfilter = PNG_FILTER_VALUE_LAST;
+# endif
+ png_byte image[16][SIZE_ROWMAX];
+
+ /* To help consistent error detection make the parts of this buffer
+ * that aren't set below all '1':
+ */
+ memset(image, 0xff, sizeof image);
+
+ if (!do_interlace &&
+ npasses != set_write_interlace_handling(pp, interlace_type))
+ png_error(pp, "write: png_set_interlace_handling failed");
+
+ /* Prepare the whole image first to avoid making it 7 times: */
+ for (y=0; y<h; ++y)
+ size_row(image[y], w * pixel_size, y);
+
+ for (pass=0; pass<npasses; ++pass)
+ {
+ /* The following two are for checking the macros: */
+ const png_uint_32 wPass = PNG_PASS_COLS(w, pass);
+
+ /* If do_interlace is set we don't call png_write_row for every
+ * row because some of them are empty. In fact, for a 1x1 image,
+ * most of them are empty!
+ */
+ for (y=0; y<h; ++y)
+ {
+ png_const_bytep row = image[y];
+ png_byte tempRow[SIZE_ROWMAX];
+
+ /* If do_interlace *and* the image is interlaced we
+ * need a reduced interlace row; this may be reduced
+ * to empty.
+ */
+ if (do_interlace && interlace_type == PNG_INTERLACE_ADAM7)
+ {
+ /* The row must not be written if it doesn't exist, notice
+ * that there are two conditions here, either the row isn't
+ * ever in the pass or the row would be but isn't wide
+ * enough to contribute any pixels. In fact the wPass test
+ * can be used to skip the whole y loop in this case.
+ */
+ if (PNG_ROW_IN_INTERLACE_PASS(y, pass) && wPass > 0)
+ {
+ /* Set to all 1's for error detection (libpng tends to
+ * set unset things to 0).
+ */
+ memset(tempRow, 0xff, sizeof tempRow);
+ interlace_row(tempRow, row, pixel_size, w, pass,
+ 0/*data always bigendian*/);
+ row = tempRow;
+ }
+ else
+ continue;
+ }
+
+# ifdef PNG_WRITE_FILTER_SUPPORTED
+ /* Only get to here if the row has some pixels in it, set the
+ * filters to 'all' for the very first row and thereafter to a
+ * single filter. It isn't well documented, but png_set_filter
+ * does accept a filter number (per the spec) as well as a bit
+ * mask.
+ *
+ * The apparent wackiness of decrementing nfilter rather than
+ * incrementing is so that Paeth gets used in all images bigger
+ * than 1 row - it's the tricky one.
+ */
+ png_set_filter(pp, 0/*method*/,
+ nfilter >= PNG_FILTER_VALUE_LAST ? PNG_ALL_FILTERS : nfilter);
+
+ if (nfilter-- == 0)
+ nfilter = PNG_FILTER_VALUE_LAST-1;
+# endif
+
+ png_write_row(pp, row);
+ }
+ }
+ }
+
+#ifdef PNG_TEXT_SUPPORTED
+ {
+ static char key[] = "end marker";
+ static char comment[] = "end";
+ png_text text;
+
+ /* Use a compressed text string to test the correct interaction of text
+ * compression and IDAT compression.
+ */
+ text.compression = TEXT_COMPRESSION;
+ text.key = key;
+ text.text = comment;
+ text.text_length = (sizeof comment)-1;
+ text.itxt_length = 0;
+ text.lang = 0;
+ text.lang_key = 0;
+
+ png_set_text(pp, pi, &text, 1);
+ }
+#endif
+
+ png_write_end(pp, pi);
+
+ /* And store this under the appropriate id, then clean up. */
+ store_storefile(ps, id);
+
+ store_write_reset(ps);
+ }
+
+ Catch(fault)
+ {
+ /* Use the png_store returned by the exception. This may help the compiler
+ * because 'ps' is not used in this branch of the setjmp. Note that fault
+ * and ps will always be the same value.
+ */
+ store_write_reset(fault);
+ }
+}
+
+static void
+make_size(png_store* const ps, png_byte const colour_type, int bdlo,
+ int const bdhi)
+{
+ for (; bdlo <= bdhi; ++bdlo)
+ {
+ png_uint_32 width;
+
+ for (width = 1; width <= 16; ++width)
+ {
+ png_uint_32 height;
+
+ for (height = 1; height <= 16; ++height)
+ {
+ /* The four combinations of DIY interlace and interlace or not -
+ * no interlace + DIY should be identical to no interlace with
+ * libpng doing it.
+ */
+ make_size_image(ps, colour_type, DEPTH(bdlo), PNG_INTERLACE_NONE,
+ width, height, 0);
+ make_size_image(ps, colour_type, DEPTH(bdlo), PNG_INTERLACE_NONE,
+ width, height, 1);
+# ifdef PNG_WRITE_INTERLACING_SUPPORTED
+ make_size_image(ps, colour_type, DEPTH(bdlo), PNG_INTERLACE_ADAM7,
+ width, height, 0);
+# endif
+# if CAN_WRITE_INTERLACE
+ /* 1.7.0 removes the hack that prevented app write of an interlaced
+ * image if WRITE_INTERLACE was not supported
+ */
+ make_size_image(ps, colour_type, DEPTH(bdlo), PNG_INTERLACE_ADAM7,
+ width, height, 1);
+# endif
+ }
+ }
+ }
+}
+
+static void
+make_size_images(png_store *ps)
+{
+ /* This is in case of errors. */
+ safecat(ps->test, sizeof ps->test, 0, "make size images");
+
+ /* Arguments are colour_type, low bit depth, high bit depth
+ */
+ make_size(ps, 0, 0, WRITE_BDHI);
+ make_size(ps, 2, 3, WRITE_BDHI);
+ make_size(ps, 3, 0, 3 /*palette: max 8 bits*/);
+ make_size(ps, 4, 3, WRITE_BDHI);
+ make_size(ps, 6, 3, WRITE_BDHI);
+}
+
+#ifdef PNG_READ_SUPPORTED
+/* Return a row based on image id and 'y' for checking: */
+static void
+standard_row(png_const_structp pp, png_byte std[STANDARD_ROWMAX],
+ png_uint_32 id, png_uint_32 y)
+{
+ if (WIDTH_FROM_ID(id) == 0)
+ transform_row(pp, std, COL_FROM_ID(id), DEPTH_FROM_ID(id), y);
+ else
+ size_row(std, WIDTH_FROM_ID(id) * bit_size(pp, COL_FROM_ID(id),
+ DEPTH_FROM_ID(id)), y);
+}
+#endif /* PNG_READ_SUPPORTED */
+
+/* Tests - individual test cases */
+/* Like 'make_standard' but errors are deliberately introduced into the calls
+ * to ensure that they get detected - it should not be possible to write an
+ * invalid image with libpng!
+ */
+/* TODO: the 'set' functions can probably all be made to take a
+ * png_const_structp rather than a modifiable one.
+ */
+#ifdef PNG_WARNINGS_SUPPORTED
+static void
+sBIT0_error_fn(png_structp pp, png_infop pi)
+{
+ /* 0 is invalid... */
+ png_color_8 bad;
+ bad.red = bad.green = bad.blue = bad.gray = bad.alpha = 0;
+ png_set_sBIT(pp, pi, &bad);
+}
+
+static void
+sBIT_error_fn(png_structp pp, png_infop pi)
+{
+ png_byte bit_depth;
+ png_color_8 bad;
+
+ if (png_get_color_type(pp, pi) == PNG_COLOR_TYPE_PALETTE)
+ bit_depth = 8;
+
+ else
+ bit_depth = png_get_bit_depth(pp, pi);
+
+ /* Now we know the bit depth we can easily generate an invalid sBIT entry */
+ bad.red = bad.green = bad.blue = bad.gray = bad.alpha =
+ (png_byte)(bit_depth+1);
+ png_set_sBIT(pp, pi, &bad);
+}
+
+static const struct
+{
+ void (*fn)(png_structp, png_infop);
+ const char *msg;
+ unsigned int warning :1; /* the error is a warning... */
+} error_test[] =
+ {
+ /* no warnings makes these errors undetectable prior to 1.7.0 */
+ { sBIT0_error_fn, "sBIT(0): failed to detect error",
+ PNG_LIBPNG_VER < 10700 },
+
+ { sBIT_error_fn, "sBIT(too big): failed to detect error",
+ PNG_LIBPNG_VER < 10700 },
+ };
+
+static void
+make_error(png_store* const ps, png_byte const colour_type,
+ png_byte bit_depth, int interlace_type, int test, png_const_charp name)
+{
+ context(ps, fault);
+
+ check_interlace_type(interlace_type);
+
+ Try
+ {
+ png_infop pi;
+ const png_structp pp = set_store_for_write(ps, &pi, name);
+ png_uint_32 w, h;
+ gnu_volatile(pp)
+
+ if (pp == NULL)
+ Throw ps;
+
+ w = transform_width(pp, colour_type, bit_depth);
+ gnu_volatile(w)
+ h = transform_height(pp, colour_type, bit_depth);
+ gnu_volatile(h)
+ png_set_IHDR(pp, pi, w, h, bit_depth, colour_type, interlace_type,
+ PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+
+ if (colour_type == 3) /* palette */
+ init_standard_palette(ps, pp, pi, 1U << bit_depth, 0/*do tRNS*/);
+
+ /* Time for a few errors; these are in various optional chunks, the
+ * standard tests test the standard chunks pretty well.
+ */
+# define exception__prev exception_prev_1
+# define exception__env exception_env_1
+ Try
+ {
+ gnu_volatile(exception__prev)
+
+ /* Expect this to throw: */
+ ps->expect_error = !error_test[test].warning;
+ ps->expect_warning = error_test[test].warning;
+ ps->saw_warning = 0;
+ error_test[test].fn(pp, pi);
+
+ /* Normally the error is only detected here: */
+ png_write_info(pp, pi);
+
+ /* And handle the case where it was only a warning: */
+ if (ps->expect_warning && ps->saw_warning)
+ Throw ps;
+
+ /* If we get here there is a problem, we have success - no error or
+ * no warning - when we shouldn't have success. Log an error.
+ */
+ store_log(ps, pp, error_test[test].msg, 1 /*error*/);
+ }
+
+ Catch (fault)
+ { /* expected exit */
+ }
+#undef exception__prev
+#undef exception__env
+
+ /* And clear these flags */
+ ps->expect_error = 0;
+ ps->expect_warning = 0;
+
+ /* Now write the whole image, just to make sure that the detected, or
+ * undetected, errro has not created problems inside libpng.
+ */
+ if (png_get_rowbytes(pp, pi) !=
+ transform_rowsize(pp, colour_type, bit_depth))
+ png_error(pp, "row size incorrect");
+
+ else
+ {
+ int npasses = set_write_interlace_handling(pp, interlace_type);
+ int pass;
+
+ if (npasses != npasses_from_interlace_type(pp, interlace_type))
+ png_error(pp, "write: png_set_interlace_handling failed");
+
+ for (pass=0; pass<npasses; ++pass)
+ {
+ png_uint_32 y;
+
+ for (y=0; y<h; ++y)
+ {
+ png_byte buffer[TRANSFORM_ROWMAX];
+
+ transform_row(pp, buffer, colour_type, bit_depth, y);
+
+# if do_own_interlace
+ /* If do_own_interlace *and* the image is interlaced we need a
+ * reduced interlace row; this may be reduced to empty.
+ */
+ if (interlace_type == PNG_INTERLACE_ADAM7)
+ {
+ /* The row must not be written if it doesn't exist, notice
+ * that there are two conditions here, either the row isn't
+ * ever in the pass or the row would be but isn't wide
+ * enough to contribute any pixels. In fact the wPass test
+ * can be used to skip the whole y loop in this case.
+ */
+ if (PNG_ROW_IN_INTERLACE_PASS(y, pass) &&
+ PNG_PASS_COLS(w, pass) > 0)
+ interlace_row(buffer, buffer,
+ bit_size(pp, colour_type, bit_depth), w, pass,
+ 0/*data always bigendian*/);
+ else
+ continue;
+ }
+# endif /* do_own_interlace */
+
+ png_write_row(pp, buffer);
+ }
+ }
+ }
+
+ png_write_end(pp, pi);
+
+ /* The following deletes the file that was just written. */
+ store_write_reset(ps);
+ }
+
+ Catch(fault)
+ {
+ store_write_reset(fault);
+ }
+}
+
+static int
+make_errors(png_modifier* const pm, png_byte const colour_type,
+ int bdlo, int const bdhi)
+{
+ for (; bdlo <= bdhi; ++bdlo)
+ {
+ int interlace_type;
+
+ for (interlace_type = PNG_INTERLACE_NONE;
+ interlace_type < INTERLACE_LAST; ++interlace_type)
+ {
+ unsigned int test;
+ char name[FILE_NAME_SIZE];
+
+ standard_name(name, sizeof name, 0, colour_type, 1<<bdlo, 0,
+ interlace_type, 0, 0, do_own_interlace);
+
+ for (test=0; test<ARRAY_SIZE(error_test); ++test)
+ {
+ make_error(&pm->this, colour_type, DEPTH(bdlo), interlace_type,
+ test, name);
+
+ if (fail(pm))
+ return 0;
+ }
+ }
+ }
+
+ return 1; /* keep going */
+}
+#endif /* PNG_WARNINGS_SUPPORTED */
+
+static void
+perform_error_test(png_modifier *pm)
+{
+#ifdef PNG_WARNINGS_SUPPORTED /* else there are no cases that work! */
+ /* Need to do this here because we just write in this test. */
+ safecat(pm->this.test, sizeof pm->this.test, 0, "error test");
+
+ if (!make_errors(pm, 0, 0, WRITE_BDHI))
+ return;
+
+ if (!make_errors(pm, 2, 3, WRITE_BDHI))
+ return;
+
+ if (!make_errors(pm, 3, 0, 3))
+ return;
+
+ if (!make_errors(pm, 4, 3, WRITE_BDHI))
+ return;
+
+ if (!make_errors(pm, 6, 3, WRITE_BDHI))
+ return;
+#else
+ UNUSED(pm)
+#endif
+}
+
+/* This is just to validate the internal PNG formatting code - if this fails
+ * then the warning messages the library outputs will probably be garbage.
+ */
+static void
+perform_formatting_test(png_store *ps)
+{
+#ifdef PNG_TIME_RFC1123_SUPPORTED
+ /* The handle into the formatting code is the RFC1123 support; this test does
+ * nothing if that is compiled out.
+ */
+ context(ps, fault);
+
+ Try
+ {
+ png_const_charp correct = "29 Aug 2079 13:53:60 +0000";
+ png_const_charp result;
+# if PNG_LIBPNG_VER >= 10600
+ char timestring[29];
+# endif
+ png_structp pp;
+ png_time pt;
+
+ pp = set_store_for_write(ps, NULL, "libpng formatting test");
+
+ if (pp == NULL)
+ Throw ps;
+
+
+ /* Arbitrary settings: */
+ pt.year = 2079;
+ pt.month = 8;
+ pt.day = 29;
+ pt.hour = 13;
+ pt.minute = 53;
+ pt.second = 60; /* a leap second */
+
+# if PNG_LIBPNG_VER < 10600
+ result = png_convert_to_rfc1123(pp, &pt);
+# else
+ if (png_convert_to_rfc1123_buffer(timestring, &pt))
+ result = timestring;
+
+ else
+ result = NULL;
+# endif
+
+ if (result == NULL)
+ png_error(pp, "png_convert_to_rfc1123 failed");
+
+ if (strcmp(result, correct) != 0)
+ {
+ size_t pos = 0;
+ char msg[128];
+
+ pos = safecat(msg, sizeof msg, pos, "png_convert_to_rfc1123(");
+ pos = safecat(msg, sizeof msg, pos, correct);
+ pos = safecat(msg, sizeof msg, pos, ") returned: '");
+ pos = safecat(msg, sizeof msg, pos, result);
+ pos = safecat(msg, sizeof msg, pos, "'");
+
+ png_error(pp, msg);
+ }
+
+ store_write_reset(ps);
+ }
+
+ Catch(fault)
+ {
+ store_write_reset(fault);
+ }
+#else
+ UNUSED(ps)
+#endif
+}
+
+#ifdef PNG_READ_SUPPORTED
+/* Because we want to use the same code in both the progressive reader and the
+ * sequential reader it is necessary to deal with the fact that the progressive
+ * reader callbacks only have one parameter (png_get_progressive_ptr()), so this
+ * must contain all the test parameters and all the local variables directly
+ * accessible to the sequential reader implementation.
+ *
+ * The technique adopted is to reinvent part of what Dijkstra termed a
+ * 'display'; an array of pointers to the stack frames of enclosing functions so
+ * that a nested function definition can access the local (C auto) variables of
+ * the functions that contain its definition. In fact C provides the first
+ * pointer (the local variables - the stack frame pointer) and the last (the
+ * global variables - the BCPL global vector typically implemented as global
+ * addresses), this code requires one more pointer to make the display - the
+ * local variables (and function call parameters) of the function that actually
+ * invokes either the progressive or sequential reader.
+ *
+ * Perhaps confusingly this technique is confounded with classes - the
+ * 'standard_display' defined here is sub-classed as the 'gamma_display' below.
+ * A gamma_display is a standard_display, taking advantage of the ANSI-C
+ * requirement that the pointer to the first member of a structure must be the
+ * same as the pointer to the structure. This allows us to reuse standard_
+ * functions in the gamma test code; something that could not be done with
+ * nested functions!
+ */
+typedef struct standard_display
+{
+ png_store* ps; /* Test parameters (passed to the function) */
+ png_byte colour_type;
+ png_byte bit_depth;
+ png_byte red_sBIT; /* Input data sBIT values. */
+ png_byte green_sBIT;
+ png_byte blue_sBIT;
+ png_byte alpha_sBIT;
+ png_byte interlace_type;
+ png_byte filler; /* Output has a filler */
+ png_uint_32 id; /* Calculated file ID */
+ png_uint_32 w; /* Width of image */
+ png_uint_32 h; /* Height of image */
+ int npasses; /* Number of interlaced passes */
+ png_uint_32 pixel_size; /* Width of one pixel in bits */
+ png_uint_32 bit_width; /* Width of output row in bits */
+ size_t cbRow; /* Bytes in a row of the output image */
+ int do_interlace; /* Do interlacing internally */
+ int littleendian; /* App (row) data is little endian */
+ int is_transparent; /* Transparency information was present. */
+ int has_tRNS; /* color type GRAY or RGB with a tRNS chunk. */
+ int speed; /* Doing a speed test */
+ int use_update_info;/* Call update_info, not start_image */
+ struct
+ {
+ png_uint_16 red;
+ png_uint_16 green;
+ png_uint_16 blue;
+ } transparent; /* The transparent color, if set. */
+ int npalette; /* Number of entries in the palette. */
+ store_palette
+ palette;
+} standard_display;
+
+static void
+standard_display_init(standard_display *dp, png_store* ps, png_uint_32 id,
+ int do_interlace, int use_update_info)
+{
+ memset(dp, 0, sizeof *dp);
+
+ dp->ps = ps;
+ dp->colour_type = COL_FROM_ID(id);
+ dp->bit_depth = DEPTH_FROM_ID(id);
+ if (dp->bit_depth < 1 || dp->bit_depth > 16)
+ internal_error(ps, "internal: bad bit depth");
+ if (dp->colour_type == 3)
+ dp->red_sBIT = dp->blue_sBIT = dp->green_sBIT = dp->alpha_sBIT = 8;
+ else
+ dp->red_sBIT = dp->blue_sBIT = dp->green_sBIT = dp->alpha_sBIT =
+ dp->bit_depth;
+ dp->interlace_type = INTERLACE_FROM_ID(id);
+ check_interlace_type(dp->interlace_type);
+ dp->id = id;
+ /* All the rest are filled in after the read_info: */
+ dp->w = 0;
+ dp->h = 0;
+ dp->npasses = 0;
+ dp->pixel_size = 0;
+ dp->bit_width = 0;
+ dp->cbRow = 0;
+ dp->do_interlace = do_interlace;
+ dp->littleendian = 0;
+ dp->is_transparent = 0;
+ dp->speed = ps->speed;
+ dp->use_update_info = use_update_info;
+ dp->npalette = 0;
+ /* Preset the transparent color to black: */
+ memset(&dp->transparent, 0, sizeof dp->transparent);
+ /* Preset the palette to full intensity/opaque througout: */
+ memset(dp->palette, 0xff, sizeof dp->palette);
+}
+
+/* Initialize the palette fields - this must be done later because the palette
+ * comes from the particular png_store_file that is selected.
+ */
+static void
+standard_palette_init(standard_display *dp)
+{
+ store_palette_entry *palette = store_current_palette(dp->ps, &dp->npalette);
+
+ /* The remaining entries remain white/opaque. */
+ if (dp->npalette > 0)
+ {
+ int i = dp->npalette;
+ memcpy(dp->palette, palette, i * sizeof *palette);
+
+ /* Check for a non-opaque palette entry: */
+ while (--i >= 0)
+ if (palette[i].alpha < 255)
+ break;
+
+# ifdef __GNUC__
+ /* GCC can't handle the more obviously optimizable version. */
+ if (i >= 0)
+ dp->is_transparent = 1;
+ else
+ dp->is_transparent = 0;
+# else
+ dp->is_transparent = (i >= 0);
+# endif
+ }
+}
+
+/* Utility to read the palette from the PNG file and convert it into
+ * store_palette format. This returns 1 if there is any transparency in the
+ * palette (it does not check for a transparent colour in the non-palette case.)
+ */
+static int
+read_palette(store_palette palette, int *npalette, png_const_structp pp,
+ png_infop pi)
+{
+ png_colorp pal;
+ png_bytep trans_alpha;
+ int num;
+
+ pal = 0;
+ *npalette = -1;
+
+ if (png_get_PLTE(pp, pi, &pal, npalette) & PNG_INFO_PLTE)
+ {
+ int i = *npalette;
+
+ if (i <= 0 || i > 256)
+ png_error(pp, "validate: invalid PLTE count");
+
+ while (--i >= 0)
+ {
+ palette[i].red = pal[i].red;
+ palette[i].green = pal[i].green;
+ palette[i].blue = pal[i].blue;
+ }
+
+ /* Mark the remainder of the entries with a flag value (other than
+ * white/opaque which is the flag value stored above.)
+ */
+ memset(palette + *npalette, 126, (256-*npalette) * sizeof *palette);
+ }
+
+ else /* !png_get_PLTE */
+ {
+ if (*npalette != (-1))
+ png_error(pp, "validate: invalid PLTE result");
+ /* But there is no palette, so record this: */
+ *npalette = 0;
+ memset(palette, 113, sizeof (store_palette));
+ }
+
+ trans_alpha = 0;
+ num = 2; /* force error below */
+ if ((png_get_tRNS(pp, pi, &trans_alpha, &num, 0) & PNG_INFO_tRNS) != 0 &&
+ (trans_alpha != NULL || num != 1/*returns 1 for a transparent color*/) &&
+ /* Oops, if a palette tRNS gets expanded png_read_update_info (at least so
+ * far as 1.5.4) does not remove the trans_alpha pointer, only num_trans,
+ * so in the above call we get a success, we get a pointer (who knows what
+ * to) and we get num_trans == 0:
+ */
+ !(trans_alpha != NULL && num == 0)) /* TODO: fix this in libpng. */
+ {
+ int i;
+
+ /* Any of these are crash-worthy - given the implementation of
+ * png_get_tRNS up to 1.5 an app won't crash if it just checks the
+ * result above and fails to check that the variables it passed have
+ * actually been filled in! Note that if the app were to pass the
+ * last, png_color_16p, variable too it couldn't rely on this.
+ */
+ if (trans_alpha == NULL || num <= 0 || num > 256 || num > *npalette)
+ png_error(pp, "validate: unexpected png_get_tRNS (palette) result");
+
+ for (i=0; i<num; ++i)
+ palette[i].alpha = trans_alpha[i];
+
+ for (num=*npalette; i<num; ++i)
+ palette[i].alpha = 255;
+
+ for (; i<256; ++i)
+ palette[i].alpha = 33; /* flag value */
+
+ return 1; /* transparency */
+ }
+
+ else
+ {
+ /* No palette transparency - just set the alpha channel to opaque. */
+ int i;
+
+ for (i=0, num=*npalette; i<num; ++i)
+ palette[i].alpha = 255;
+
+ for (; i<256; ++i)
+ palette[i].alpha = 55; /* flag value */
+
+ return 0; /* no transparency */
+ }
+}
+
+/* Utility to validate the palette if it should not have changed (the
+ * non-transform case).
+ */
+static void
+standard_palette_validate(standard_display *dp, png_const_structp pp,
+ png_infop pi)
+{
+ int npalette;
+ store_palette palette;
+
+ if (read_palette(palette, &npalette, pp, pi) != dp->is_transparent)
+ png_error(pp, "validate: palette transparency changed");
+
+ if (npalette != dp->npalette)
+ {
+ size_t pos = 0;
+ char msg[64];
+
+ pos = safecat(msg, sizeof msg, pos, "validate: palette size changed: ");
+ pos = safecatn(msg, sizeof msg, pos, dp->npalette);
+ pos = safecat(msg, sizeof msg, pos, " -> ");
+ pos = safecatn(msg, sizeof msg, pos, npalette);
+ png_error(pp, msg);
+ }
+
+ {
+ int i = npalette; /* npalette is aliased */
+
+ while (--i >= 0)
+ if (palette[i].red != dp->palette[i].red ||
+ palette[i].green != dp->palette[i].green ||
+ palette[i].blue != dp->palette[i].blue ||
+ palette[i].alpha != dp->palette[i].alpha)
+ png_error(pp, "validate: PLTE or tRNS chunk changed");
+ }
+}
+
+/* By passing a 'standard_display' the progressive callbacks can be used
+ * directly by the sequential code, the functions suffixed "_imp" are the
+ * implementations, the functions without the suffix are the callbacks.
+ *
+ * The code for the info callback is split into two because this callback calls
+ * png_read_update_info or png_start_read_image and what gets called depends on
+ * whether the info needs updating (we want to test both calls in pngvalid.)
+ */
+static void
+standard_info_part1(standard_display *dp, png_structp pp, png_infop pi)
+{
+ if (png_get_bit_depth(pp, pi) != dp->bit_depth)
+ png_error(pp, "validate: bit depth changed");
+
+ if (png_get_color_type(pp, pi) != dp->colour_type)
+ png_error(pp, "validate: color type changed");
+
+ if (png_get_filter_type(pp, pi) != PNG_FILTER_TYPE_BASE)
+ png_error(pp, "validate: filter type changed");
+
+ if (png_get_interlace_type(pp, pi) != dp->interlace_type)
+ png_error(pp, "validate: interlacing changed");
+
+ if (png_get_compression_type(pp, pi) != PNG_COMPRESSION_TYPE_BASE)
+ png_error(pp, "validate: compression type changed");
+
+ dp->w = png_get_image_width(pp, pi);
+
+ if (dp->w != standard_width(pp, dp->id))
+ png_error(pp, "validate: image width changed");
+
+ dp->h = png_get_image_height(pp, pi);
+
+ if (dp->h != standard_height(pp, dp->id))
+ png_error(pp, "validate: image height changed");
+
+ /* Record (but don't check at present) the input sBIT according to the colour
+ * type information.
+ */
+ {
+ png_color_8p sBIT = 0;
+
+ if (png_get_sBIT(pp, pi, &sBIT) & PNG_INFO_sBIT)
+ {
+ int sBIT_invalid = 0;
+
+ if (sBIT == 0)
+ png_error(pp, "validate: unexpected png_get_sBIT result");
+
+ if (dp->colour_type & PNG_COLOR_MASK_COLOR)
+ {
+ if (sBIT->red == 0 || sBIT->red > dp->bit_depth)
+ sBIT_invalid = 1;
+ else
+ dp->red_sBIT = sBIT->red;
+
+ if (sBIT->green == 0 || sBIT->green > dp->bit_depth)
+ sBIT_invalid = 1;
+ else
+ dp->green_sBIT = sBIT->green;
+
+ if (sBIT->blue == 0 || sBIT->blue > dp->bit_depth)
+ sBIT_invalid = 1;
+ else
+ dp->blue_sBIT = sBIT->blue;
+ }
+
+ else /* !COLOR */
+ {
+ if (sBIT->gray == 0 || sBIT->gray > dp->bit_depth)
+ sBIT_invalid = 1;
+ else
+ dp->blue_sBIT = dp->green_sBIT = dp->red_sBIT = sBIT->gray;
+ }
+
+ /* All 8 bits in tRNS for a palette image are significant - see the
+ * spec.
+ */
+ if (dp->colour_type & PNG_COLOR_MASK_ALPHA)
+ {
+ if (sBIT->alpha == 0 || sBIT->alpha > dp->bit_depth)
+ sBIT_invalid = 1;
+ else
+ dp->alpha_sBIT = sBIT->alpha;
+ }
+
+ if (sBIT_invalid)
+ png_error(pp, "validate: sBIT value out of range");
+ }
+ }
+
+ /* Important: this is validating the value *before* any transforms have been
+ * put in place. It doesn't matter for the standard tests, where there are
+ * no transforms, but it does for other tests where rowbytes may change after
+ * png_read_update_info.
+ */
+ if (png_get_rowbytes(pp, pi) != standard_rowsize(pp, dp->id))
+ png_error(pp, "validate: row size changed");
+
+ /* Validate the colour type 3 palette (this can be present on other color
+ * types.)
+ */
+ standard_palette_validate(dp, pp, pi);
+
+ /* In any case always check for a tranparent color (notice that the
+ * colour type 3 case must not give a successful return on the get_tRNS call
+ * with these arguments!)
+ */
+ {
+ png_color_16p trans_color = 0;
+
+ if (png_get_tRNS(pp, pi, 0, 0, &trans_color) & PNG_INFO_tRNS)
+ {
+ if (trans_color == 0)
+ png_error(pp, "validate: unexpected png_get_tRNS (color) result");
+
+ switch (dp->colour_type)
+ {
+ case 0:
+ dp->transparent.red = dp->transparent.green = dp->transparent.blue =
+ trans_color->gray;
+ dp->has_tRNS = 1;
+ break;
+
+ case 2:
+ dp->transparent.red = trans_color->red;
+ dp->transparent.green = trans_color->green;
+ dp->transparent.blue = trans_color->blue;
+ dp->has_tRNS = 1;
+ break;
+
+ case 3:
+ /* Not expected because it should result in the array case
+ * above.
+ */
+ png_error(pp, "validate: unexpected png_get_tRNS result");
+ break;
+
+ default:
+ png_error(pp, "validate: invalid tRNS chunk with alpha image");
+ }
+ }
+ }
+
+ /* Read the number of passes - expected to match the value used when
+ * creating the image (interlaced or not). This has the side effect of
+ * turning on interlace handling (if do_interlace is not set.)
+ */
+ dp->npasses = npasses_from_interlace_type(pp, dp->interlace_type);
+ if (!dp->do_interlace)
+ {
+# ifdef PNG_READ_INTERLACING_SUPPORTED
+ if (dp->npasses != png_set_interlace_handling(pp))
+ png_error(pp, "validate: file changed interlace type");
+# else /* !READ_INTERLACING */
+ /* This should never happen: the relevant tests (!do_interlace) should
+ * not be run.
+ */
+ if (dp->npasses > 1)
+ png_error(pp, "validate: no libpng interlace support");
+# endif /* !READ_INTERLACING */
+ }
+
+ /* Caller calls png_read_update_info or png_start_read_image now, then calls
+ * part2.
+ */
+}
+
+/* This must be called *after* the png_read_update_info call to get the correct
+ * 'rowbytes' value, otherwise png_get_rowbytes will refer to the untransformed
+ * image.
+ */
+static void
+standard_info_part2(standard_display *dp, png_const_structp pp,
+ png_const_infop pi, int nImages)
+{
+ /* Record cbRow now that it can be found. */
+ {
+ png_byte ct = png_get_color_type(pp, pi);
+ png_byte bd = png_get_bit_depth(pp, pi);
+
+ if (bd >= 8 && (ct == PNG_COLOR_TYPE_RGB || ct == PNG_COLOR_TYPE_GRAY) &&
+ dp->filler)
+ ct |= 4; /* handle filler as faked alpha channel */
+
+ dp->pixel_size = bit_size(pp, ct, bd);
+ }
+ dp->bit_width = png_get_image_width(pp, pi) * dp->pixel_size;
+ dp->cbRow = png_get_rowbytes(pp, pi);
+
+ /* Validate the rowbytes here again. */
+ if (dp->cbRow != (dp->bit_width+7)/8)
+ png_error(pp, "bad png_get_rowbytes calculation");
+
+ /* Then ensure there is enough space for the output image(s). */
+ store_ensure_image(dp->ps, pp, nImages, dp->cbRow, dp->h);
+}
+
+static void
+standard_info_imp(standard_display *dp, png_structp pp, png_infop pi,
+ int nImages)
+{
+ /* Note that the validation routine has the side effect of turning on
+ * interlace handling in the subsequent code.
+ */
+ standard_info_part1(dp, pp, pi);
+
+ /* And the info callback has to call this (or png_read_update_info - see
+ * below in the png_modifier code for that variant.
+ */
+ if (dp->use_update_info)
+ {
+ /* For debugging the effect of multiple calls: */
+ int i = dp->use_update_info;
+ while (i-- > 0)
+ png_read_update_info(pp, pi);
+ }
+
+ else
+ png_start_read_image(pp);
+
+ /* Validate the height, width and rowbytes plus ensure that sufficient buffer
+ * exists for decoding the image.
+ */
+ standard_info_part2(dp, pp, pi, nImages);
+}
+
+static void PNGCBAPI
+standard_info(png_structp pp, png_infop pi)
+{
+ standard_display *dp = voidcast(standard_display*,
+ png_get_progressive_ptr(pp));
+
+ /* Call with nImages==1 because the progressive reader can only produce one
+ * image.
+ */
+ standard_info_imp(dp, pp, pi, 1 /*only one image*/);
+}
+
+static void PNGCBAPI
+progressive_row(png_structp ppIn, png_bytep new_row, png_uint_32 y, int pass)
+{
+ png_const_structp pp = ppIn;
+ const standard_display *dp = voidcast(standard_display*,
+ png_get_progressive_ptr(pp));
+
+ /* When handling interlacing some rows will be absent in each pass, the
+ * callback still gets called, but with a NULL pointer. This is checked
+ * in the 'else' clause below. We need our own 'cbRow', but we can't call
+ * png_get_rowbytes because we got no info structure.
+ */
+ if (new_row != NULL)
+ {
+ png_bytep row;
+
+ /* In the case where the reader doesn't do the interlace it gives
+ * us the y in the sub-image:
+ */
+ if (dp->do_interlace && dp->interlace_type == PNG_INTERLACE_ADAM7)
+ {
+#ifdef PNG_USER_TRANSFORM_INFO_SUPPORTED
+ /* Use this opportunity to validate the png 'current' APIs: */
+ if (y != png_get_current_row_number(pp))
+ png_error(pp, "png_get_current_row_number is broken");
+
+ if (pass != png_get_current_pass_number(pp))
+ png_error(pp, "png_get_current_pass_number is broken");
+#endif /* USER_TRANSFORM_INFO */
+
+ y = PNG_ROW_FROM_PASS_ROW(y, pass);
+ }
+
+ /* Validate this just in case. */
+ if (y >= dp->h)
+ png_error(pp, "invalid y to progressive row callback");
+
+ row = store_image_row(dp->ps, pp, 0, y);
+
+ /* Combine the new row into the old: */
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+ if (dp->do_interlace)
+#endif /* READ_INTERLACING */
+ {
+ if (dp->interlace_type == PNG_INTERLACE_ADAM7)
+ deinterlace_row(row, new_row, dp->pixel_size, dp->w, pass,
+ dp->littleendian);
+ else
+ row_copy(row, new_row, dp->pixel_size * dp->w, dp->littleendian);
+ }
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+ else
+ png_progressive_combine_row(pp, row, new_row);
+#endif /* PNG_READ_INTERLACING_SUPPORTED */
+ }
+
+ else if (dp->interlace_type == PNG_INTERLACE_ADAM7 &&
+ PNG_ROW_IN_INTERLACE_PASS(y, pass) &&
+ PNG_PASS_COLS(dp->w, pass) > 0)
+ png_error(pp, "missing row in progressive de-interlacing");
+}
+
+static void
+sequential_row(standard_display *dp, png_structp pp, png_infop pi,
+ const int iImage, const int iDisplay)
+{
+ const int npasses = dp->npasses;
+ const int do_interlace = dp->do_interlace &&
+ dp->interlace_type == PNG_INTERLACE_ADAM7;
+ const png_uint_32 height = standard_height(pp, dp->id);
+ const png_uint_32 width = standard_width(pp, dp->id);
+ const png_store* ps = dp->ps;
+ int pass;
+
+ for (pass=0; pass<npasses; ++pass)
+ {
+ png_uint_32 y;
+ png_uint_32 wPass = PNG_PASS_COLS(width, pass);
+
+ for (y=0; y<height; ++y)
+ {
+ if (do_interlace)
+ {
+ /* wPass may be zero or this row may not be in this pass.
+ * png_read_row must not be called in either case.
+ */
+ if (wPass > 0 && PNG_ROW_IN_INTERLACE_PASS(y, pass))
+ {
+ /* Read the row into a pair of temporary buffers, then do the
+ * merge here into the output rows.
+ */
+ png_byte row[STANDARD_ROWMAX], display[STANDARD_ROWMAX];
+
+ /* The following aids (to some extent) error detection - we can
+ * see where png_read_row wrote. Use opposite values in row and
+ * display to make this easier. Don't use 0xff (which is used in
+ * the image write code to fill unused bits) or 0 (which is a
+ * likely value to overwrite unused bits with).
+ */
+ memset(row, 0xc5, sizeof row);
+ memset(display, 0x5c, sizeof display);
+
+ png_read_row(pp, row, display);
+
+ if (iImage >= 0)
+ deinterlace_row(store_image_row(ps, pp, iImage, y), row,
+ dp->pixel_size, dp->w, pass, dp->littleendian);
+
+ if (iDisplay >= 0)
+ deinterlace_row(store_image_row(ps, pp, iDisplay, y), display,
+ dp->pixel_size, dp->w, pass, dp->littleendian);
+ }
+ }
+ else
+ png_read_row(pp,
+ iImage >= 0 ? store_image_row(ps, pp, iImage, y) : NULL,
+ iDisplay >= 0 ? store_image_row(ps, pp, iDisplay, y) : NULL);
+ }
+ }
+
+ /* And finish the read operation (only really necessary if the caller wants
+ * to find additional data in png_info from chunks after the last IDAT.)
+ */
+ png_read_end(pp, pi);
+}
+
+#ifdef PNG_TEXT_SUPPORTED
+static void
+standard_check_text(png_const_structp pp, png_const_textp tp,
+ png_const_charp keyword, png_const_charp text)
+{
+ char msg[1024];
+ size_t pos = safecat(msg, sizeof msg, 0, "text: ");
+ size_t ok;
+
+ pos = safecat(msg, sizeof msg, pos, keyword);
+ pos = safecat(msg, sizeof msg, pos, ": ");
+ ok = pos;
+
+ if (tp->compression != TEXT_COMPRESSION)
+ {
+ char buf[64];
+
+ sprintf(buf, "compression [%d->%d], ", TEXT_COMPRESSION,
+ tp->compression);
+ pos = safecat(msg, sizeof msg, pos, buf);
+ }
+
+ if (tp->key == NULL || strcmp(tp->key, keyword) != 0)
+ {
+ pos = safecat(msg, sizeof msg, pos, "keyword \"");
+ if (tp->key != NULL)
+ {
+ pos = safecat(msg, sizeof msg, pos, tp->key);
+ pos = safecat(msg, sizeof msg, pos, "\", ");
+ }
+
+ else
+ pos = safecat(msg, sizeof msg, pos, "null, ");
+ }
+
+ if (tp->text == NULL)
+ pos = safecat(msg, sizeof msg, pos, "text lost, ");
+
+ else
+ {
+ if (tp->text_length != strlen(text))
+ {
+ char buf[64];
+ sprintf(buf, "text length changed[%lu->%lu], ",
+ (unsigned long)strlen(text), (unsigned long)tp->text_length);
+ pos = safecat(msg, sizeof msg, pos, buf);
+ }
+
+ if (strcmp(tp->text, text) != 0)
+ {
+ pos = safecat(msg, sizeof msg, pos, "text becomes \"");
+ pos = safecat(msg, sizeof msg, pos, tp->text);
+ pos = safecat(msg, sizeof msg, pos, "\" (was \"");
+ pos = safecat(msg, sizeof msg, pos, text);
+ pos = safecat(msg, sizeof msg, pos, "\"), ");
+ }
+ }
+
+ if (tp->itxt_length != 0)
+ pos = safecat(msg, sizeof msg, pos, "iTXt length set, ");
+
+ if (tp->lang != NULL)
+ {
+ pos = safecat(msg, sizeof msg, pos, "iTXt language \"");
+ pos = safecat(msg, sizeof msg, pos, tp->lang);
+ pos = safecat(msg, sizeof msg, pos, "\", ");
+ }
+
+ if (tp->lang_key != NULL)
+ {
+ pos = safecat(msg, sizeof msg, pos, "iTXt keyword \"");
+ pos = safecat(msg, sizeof msg, pos, tp->lang_key);
+ pos = safecat(msg, sizeof msg, pos, "\", ");
+ }
+
+ if (pos > ok)
+ {
+ msg[pos-2] = '\0'; /* Remove the ", " at the end */
+ png_error(pp, msg);
+ }
+}
+
+static void
+standard_text_validate(standard_display *dp, png_const_structp pp,
+ png_infop pi, int check_end)
+{
+ png_textp tp = NULL;
+ png_uint_32 num_text = png_get_text(pp, pi, &tp, NULL);
+
+ if (num_text == 2 && tp != NULL)
+ {
+ standard_check_text(pp, tp, "image name", dp->ps->current->name);
+
+ /* This exists because prior to 1.5.18 the progressive reader left the
+ * png_struct z_stream unreset at the end of the image, so subsequent
+ * attempts to use it simply returns Z_STREAM_END.
+ */
+ if (check_end)
+ standard_check_text(pp, tp+1, "end marker", "end");
+ }
+
+ else
+ {
+ char msg[64];
+
+ sprintf(msg, "expected two text items, got %lu",
+ (unsigned long)num_text);
+ png_error(pp, msg);
+ }
+}
+#else
+# define standard_text_validate(dp,pp,pi,check_end) ((void)0)
+#endif
+
+static void
+standard_row_validate(standard_display *dp, png_const_structp pp,
+ int iImage, int iDisplay, png_uint_32 y)
+{
+ int where;
+ png_byte std[STANDARD_ROWMAX];
+
+ /* The row must be pre-initialized to the magic number here for the size
+ * tests to pass:
+ */
+ memset(std, 178, sizeof std);
+ standard_row(pp, std, dp->id, y);
+
+ /* At the end both the 'row' and 'display' arrays should end up identical.
+ * In earlier passes 'row' will be partially filled in, with only the pixels
+ * that have been read so far, but 'display' will have those pixels
+ * replicated to fill the unread pixels while reading an interlaced image.
+ */
+ if (iImage >= 0 &&
+ (where = pixel_cmp(std, store_image_row(dp->ps, pp, iImage, y),
+ dp->bit_width)) != 0)
+ {
+ char msg[64];
+ sprintf(msg, "PNG image row[%lu][%d] changed from %.2x to %.2x",
+ (unsigned long)y, where-1, std[where-1],
+ store_image_row(dp->ps, pp, iImage, y)[where-1]);
+ png_error(pp, msg);
+ }
+
+ if (iDisplay >= 0 &&
+ (where = pixel_cmp(std, store_image_row(dp->ps, pp, iDisplay, y),
+ dp->bit_width)) != 0)
+ {
+ char msg[64];
+ sprintf(msg, "display row[%lu][%d] changed from %.2x to %.2x",
+ (unsigned long)y, where-1, std[where-1],
+ store_image_row(dp->ps, pp, iDisplay, y)[where-1]);
+ png_error(pp, msg);
+ }
+}
+
+static void
+standard_image_validate(standard_display *dp, png_const_structp pp, int iImage,
+ int iDisplay)
+{
+ png_uint_32 y;
+
+ if (iImage >= 0)
+ store_image_check(dp->ps, pp, iImage);
+
+ if (iDisplay >= 0)
+ store_image_check(dp->ps, pp, iDisplay);
+
+ for (y=0; y<dp->h; ++y)
+ standard_row_validate(dp, pp, iImage, iDisplay, y);
+
+ /* This avoids false positives if the validation code is never called! */
+ dp->ps->validated = 1;
+}
+
+static void PNGCBAPI
+standard_end(png_structp ppIn, png_infop pi)
+{
+ png_const_structp pp = ppIn;
+ standard_display *dp = voidcast(standard_display*,
+ png_get_progressive_ptr(pp));
+
+ UNUSED(pi)
+
+ /* Validate the image - progressive reading only produces one variant for
+ * interlaced images.
+ */
+ standard_text_validate(dp, pp, pi,
+ PNG_LIBPNG_VER >= 10518/*check_end: see comments above*/);
+ standard_image_validate(dp, pp, 0, -1);
+}
+
+/* A single test run checking the standard image to ensure it is not damaged. */
+static void
+standard_test(png_store* const psIn, png_uint_32 const id,
+ int do_interlace, int use_update_info)
+{
+ standard_display d;
+ context(psIn, fault);
+
+ /* Set up the display (stack frame) variables from the arguments to the
+ * function and initialize the locals that are filled in later.
+ */
+ standard_display_init(&d, psIn, id, do_interlace, use_update_info);
+
+ /* Everything is protected by a Try/Catch. The functions called also
+ * typically have local Try/Catch blocks.
+ */
+ Try
+ {
+ png_structp pp;
+ png_infop pi;
+
+ /* Get a png_struct for reading the image. This will throw an error if it
+ * fails, so we don't need to check the result.
+ */
+ pp = set_store_for_read(d.ps, &pi, d.id,
+ d.do_interlace ? (d.ps->progressive ?
+ "pngvalid progressive deinterlacer" :
+ "pngvalid sequential deinterlacer") : (d.ps->progressive ?
+ "progressive reader" : "sequential reader"));
+
+ /* Initialize the palette correctly from the png_store_file. */
+ standard_palette_init(&d);
+
+ /* Introduce the correct read function. */
+ if (d.ps->progressive)
+ {
+ png_set_progressive_read_fn(pp, &d, standard_info, progressive_row,
+ standard_end);
+
+ /* Now feed data into the reader until we reach the end: */
+ store_progressive_read(d.ps, pp, pi);
+ }
+ else
+ {
+ /* Note that this takes the store, not the display. */
+ png_set_read_fn(pp, d.ps, store_read);
+
+ /* Check the header values: */
+ png_read_info(pp, pi);
+
+ /* The code tests both versions of the images that the sequential
+ * reader can produce.
+ */
+ standard_info_imp(&d, pp, pi, 2 /*images*/);
+
+ /* Need the total bytes in the image below; we can't get to this point
+ * unless the PNG file values have been checked against the expected
+ * values.
+ */
+ {
+ sequential_row(&d, pp, pi, 0, 1);
+
+ /* After the last pass loop over the rows again to check that the
+ * image is correct.
+ */
+ if (!d.speed)
+ {
+ standard_text_validate(&d, pp, pi, 1/*check_end*/);
+ standard_image_validate(&d, pp, 0, 1);
+ }
+ else
+ d.ps->validated = 1;
+ }
+ }
+
+ /* Check for validation. */
+ if (!d.ps->validated)
+ png_error(pp, "image read failed silently");
+
+ /* Successful completion. */
+ }
+
+ Catch(fault)
+ d.ps = fault; /* make sure this hasn't been clobbered. */
+
+ /* In either case clean up the store. */
+ store_read_reset(d.ps);
+}
+
+static int
+test_standard(png_modifier* const pm, png_byte const colour_type,
+ int bdlo, int const bdhi)
+{
+ for (; bdlo <= bdhi; ++bdlo)
+ {
+ int interlace_type;
+
+ for (interlace_type = PNG_INTERLACE_NONE;
+ interlace_type < INTERLACE_LAST; ++interlace_type)
+ {
+ standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
+ interlace_type, 0, 0, 0), do_read_interlace, pm->use_update_info);
+
+ if (fail(pm))
+ return 0;
+ }
+ }
+
+ return 1; /* keep going */
+}
+
+static void
+perform_standard_test(png_modifier *pm)
+{
+ /* Test each colour type over the valid range of bit depths (expressed as
+ * log2(bit_depth) in turn, stop as soon as any error is detected.
+ */
+ if (!test_standard(pm, 0, 0, READ_BDHI))
+ return;
+
+ if (!test_standard(pm, 2, 3, READ_BDHI))
+ return;
+
+ if (!test_standard(pm, 3, 0, 3))
+ return;
+
+ if (!test_standard(pm, 4, 3, READ_BDHI))
+ return;
+
+ if (!test_standard(pm, 6, 3, READ_BDHI))
+ return;
+}
+
+
+/********************************** SIZE TESTS ********************************/
+static int
+test_size(png_modifier* const pm, png_byte const colour_type,
+ int bdlo, int const bdhi)
+{
+ /* Run the tests on each combination.
+ *
+ * NOTE: on my 32 bit x86 each of the following blocks takes
+ * a total of 3.5 seconds if done across every combo of bit depth
+ * width and height. This is a waste of time in practice, hence the
+ * hinc and winc stuff:
+ */
+ static const png_byte hinc[] = {1, 3, 11, 1, 5};
+ static const png_byte winc[] = {1, 9, 5, 7, 1};
+ const int save_bdlo = bdlo;
+
+ for (; bdlo <= bdhi; ++bdlo)
+ {
+ png_uint_32 h, w;
+
+ for (h=1; h<=16; h+=hinc[bdlo]) for (w=1; w<=16; w+=winc[bdlo])
+ {
+ /* First test all the 'size' images against the sequential
+ * reader using libpng to deinterlace (where required.) This
+ * validates the write side of libpng. There are four possibilities
+ * to validate.
+ */
+ standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
+ PNG_INTERLACE_NONE, w, h, 0), 0/*do_interlace*/,
+ pm->use_update_info);
+
+ if (fail(pm))
+ return 0;
+
+ standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
+ PNG_INTERLACE_NONE, w, h, 1), 0/*do_interlace*/,
+ pm->use_update_info);
+
+ if (fail(pm))
+ return 0;
+
+ /* Now validate the interlaced read side - do_interlace true,
+ * in the progressive case this does actually make a difference
+ * to the code used in the non-interlaced case too.
+ */
+ standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
+ PNG_INTERLACE_NONE, w, h, 0), 1/*do_interlace*/,
+ pm->use_update_info);
+
+ if (fail(pm))
+ return 0;
+
+# if CAN_WRITE_INTERLACE
+ /* Validate the pngvalid code itself: */
+ standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
+ PNG_INTERLACE_ADAM7, w, h, 1), 1/*do_interlace*/,
+ pm->use_update_info);
+
+ if (fail(pm))
+ return 0;
+# endif
+ }
+ }
+
+ /* Now do the tests of libpng interlace handling, after we have made sure
+ * that the pngvalid version works:
+ */
+ for (bdlo = save_bdlo; bdlo <= bdhi; ++bdlo)
+ {
+ png_uint_32 h, w;
+
+ for (h=1; h<=16; h+=hinc[bdlo]) for (w=1; w<=16; w+=winc[bdlo])
+ {
+# ifdef PNG_READ_INTERLACING_SUPPORTED
+ /* Test with pngvalid generated interlaced images first; we have
+ * already verify these are ok (unless pngvalid has self-consistent
+ * read/write errors, which is unlikely), so this detects errors in the
+ * read side first:
+ */
+# if CAN_WRITE_INTERLACE
+ standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
+ PNG_INTERLACE_ADAM7, w, h, 1), 0/*do_interlace*/,
+ pm->use_update_info);
+
+ if (fail(pm))
+ return 0;
+# endif
+# endif /* READ_INTERLACING */
+
+# ifdef PNG_WRITE_INTERLACING_SUPPORTED
+ /* Test the libpng write side against the pngvalid read side: */
+ standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
+ PNG_INTERLACE_ADAM7, w, h, 0), 1/*do_interlace*/,
+ pm->use_update_info);
+
+ if (fail(pm))
+ return 0;
+# endif
+
+# ifdef PNG_READ_INTERLACING_SUPPORTED
+# ifdef PNG_WRITE_INTERLACING_SUPPORTED
+ /* Test both together: */
+ standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
+ PNG_INTERLACE_ADAM7, w, h, 0), 0/*do_interlace*/,
+ pm->use_update_info);
+
+ if (fail(pm))
+ return 0;
+# endif
+# endif /* READ_INTERLACING */
+ }
+ }
+
+ return 1; /* keep going */
+}
+
+static void
+perform_size_test(png_modifier *pm)
+{
+ /* Test each colour type over the valid range of bit depths (expressed as
+ * log2(bit_depth) in turn, stop as soon as any error is detected.
+ */
+ if (!test_size(pm, 0, 0, READ_BDHI))
+ return;
+
+ if (!test_size(pm, 2, 3, READ_BDHI))
+ return;
+
+ /* For the moment don't do the palette test - it's a waste of time when
+ * compared to the grayscale test.
+ */
+#if 0
+ if (!test_size(pm, 3, 0, 3))
+ return;
+#endif
+
+ if (!test_size(pm, 4, 3, READ_BDHI))
+ return;
+
+ if (!test_size(pm, 6, 3, READ_BDHI))
+ return;
+}
+
+
+/******************************* TRANSFORM TESTS ******************************/
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
+/* A set of tests to validate libpng image transforms. The possibilities here
+ * are legion because the transforms can be combined in a combinatorial
+ * fashion. To deal with this some measure of restraint is required, otherwise
+ * the tests would take forever.
+ */
+typedef struct image_pixel
+{
+ /* A local (pngvalid) representation of a PNG pixel, in all its
+ * various forms.
+ */
+ unsigned int red, green, blue, alpha; /* For non-palette images. */
+ unsigned int palette_index; /* For a palette image. */
+ png_byte colour_type; /* As in the spec. */
+ png_byte bit_depth; /* Defines bit size in row */
+ png_byte sample_depth; /* Scale of samples */
+ unsigned int have_tRNS :1; /* tRNS chunk may need processing */
+ unsigned int swap_rgb :1; /* RGB swapped to BGR */
+ unsigned int alpha_first :1; /* Alpha at start, not end */
+ unsigned int alpha_inverted :1; /* Alpha channel inverted */
+ unsigned int mono_inverted :1; /* Gray channel inverted */
+ unsigned int swap16 :1; /* Byte swap 16-bit components */
+ unsigned int littleendian :1; /* High bits on right */
+ unsigned int sig_bits :1; /* Pixel shifted (sig bits only) */
+
+ /* For checking the code calculates double precision floating point values
+ * along with an error value, accumulated from the transforms. Because an
+ * sBIT setting allows larger error bounds (indeed, by the spec, apparently
+ * up to just less than +/-1 in the scaled value) the *lowest* sBIT for each
+ * channel is stored. This sBIT value is folded in to the stored error value
+ * at the end of the application of the transforms to the pixel.
+ *
+ * If sig_bits is set above the red, green, blue and alpha values have been
+ * scaled so they only contain the significant bits of the component values.
+ */
+ double redf, greenf, bluef, alphaf;
+ double rede, greene, bluee, alphae;
+ png_byte red_sBIT, green_sBIT, blue_sBIT, alpha_sBIT;
+} image_pixel;
+
+/* Shared utility function, see below. */
+static void
+image_pixel_setf(image_pixel *this, unsigned int rMax, unsigned int gMax,
+ unsigned int bMax, unsigned int aMax)
+{
+ this->redf = this->red / (double)rMax;
+ this->greenf = this->green / (double)gMax;
+ this->bluef = this->blue / (double)bMax;
+ this->alphaf = this->alpha / (double)aMax;
+
+ if (this->red < rMax)
+ this->rede = this->redf * DBL_EPSILON;
+ else
+ this->rede = 0;
+ if (this->green < gMax)
+ this->greene = this->greenf * DBL_EPSILON;
+ else
+ this->greene = 0;
+ if (this->blue < bMax)
+ this->bluee = this->bluef * DBL_EPSILON;
+ else
+ this->bluee = 0;
+ if (this->alpha < aMax)
+ this->alphae = this->alphaf * DBL_EPSILON;
+ else
+ this->alphae = 0;
+}
+
+/* Initialize the structure for the next pixel - call this before doing any
+ * transforms and call it for each pixel since all the fields may need to be
+ * reset.
+ */
+static void
+image_pixel_init(image_pixel *this, png_const_bytep row, png_byte colour_type,
+ png_byte bit_depth, png_uint_32 x, store_palette palette,
+ const image_pixel *format /*from pngvalid transform of input*/)
+{
+ const png_byte sample_depth = (png_byte)(colour_type ==
+ PNG_COLOR_TYPE_PALETTE ? 8 : bit_depth);
+ const unsigned int max = (1U<<sample_depth)-1;
+ const int swap16 = (format != 0 && format->swap16);
+ const int littleendian = (format != 0 && format->littleendian);
+ const int sig_bits = (format != 0 && format->sig_bits);
+
+ /* Initially just set everything to the same number and the alpha to opaque.
+ * Note that this currently assumes a simple palette where entry x has colour
+ * rgb(x,x,x)!
+ */
+ this->palette_index = this->red = this->green = this->blue =
+ sample(row, colour_type, bit_depth, x, 0, swap16, littleendian);
+ this->alpha = max;
+ this->red_sBIT = this->green_sBIT = this->blue_sBIT = this->alpha_sBIT =
+ sample_depth;
+
+ /* Then override as appropriate: */
+ if (colour_type == 3) /* palette */
+ {
+ /* This permits the caller to default to the sample value. */
+ if (palette != 0)
+ {
+ const unsigned int i = this->palette_index;
+
+ this->red = palette[i].red;
+ this->green = palette[i].green;
+ this->blue = palette[i].blue;
+ this->alpha = palette[i].alpha;
+ }
+ }
+
+ else /* not palette */
+ {
+ unsigned int i = 0;
+
+ if ((colour_type & 4) != 0 && format != 0 && format->alpha_first)
+ {
+ this->alpha = this->red;
+ /* This handles the gray case for 'AG' pixels */
+ this->palette_index = this->red = this->green = this->blue =
+ sample(row, colour_type, bit_depth, x, 1, swap16, littleendian);
+ i = 1;
+ }
+
+ if (colour_type & 2)
+ {
+ /* Green is second for both BGR and RGB: */
+ this->green = sample(row, colour_type, bit_depth, x, ++i, swap16,
+ littleendian);
+
+ if (format != 0 && format->swap_rgb) /* BGR */
+ this->red = sample(row, colour_type, bit_depth, x, ++i, swap16,
+ littleendian);
+ else
+ this->blue = sample(row, colour_type, bit_depth, x, ++i, swap16,
+ littleendian);
+ }
+
+ else /* grayscale */ if (format != 0 && format->mono_inverted)
+ this->red = this->green = this->blue = this->red ^ max;
+
+ if ((colour_type & 4) != 0) /* alpha */
+ {
+ if (format == 0 || !format->alpha_first)
+ this->alpha = sample(row, colour_type, bit_depth, x, ++i, swap16,
+ littleendian);
+
+ if (format != 0 && format->alpha_inverted)
+ this->alpha ^= max;
+ }
+ }
+
+ /* Calculate the scaled values, these are simply the values divided by
+ * 'max' and the error is initialized to the double precision epsilon value
+ * from the header file.
+ */
+ image_pixel_setf(this,
+ sig_bits ? (1U << format->red_sBIT)-1 : max,
+ sig_bits ? (1U << format->green_sBIT)-1 : max,
+ sig_bits ? (1U << format->blue_sBIT)-1 : max,
+ sig_bits ? (1U << format->alpha_sBIT)-1 : max);
+
+ /* Store the input information for use in the transforms - these will
+ * modify the information.
+ */
+ this->colour_type = colour_type;
+ this->bit_depth = bit_depth;
+ this->sample_depth = sample_depth;
+ this->have_tRNS = 0;
+ this->swap_rgb = 0;
+ this->alpha_first = 0;
+ this->alpha_inverted = 0;
+ this->mono_inverted = 0;
+ this->swap16 = 0;
+ this->littleendian = 0;
+ this->sig_bits = 0;
+}
+
+#if defined PNG_READ_EXPAND_SUPPORTED || defined PNG_READ_GRAY_TO_RGB_SUPPORTED\
+ || defined PNG_READ_EXPAND_SUPPORTED || defined PNG_READ_EXPAND_16_SUPPORTED\
+ || defined PNG_READ_BACKGROUND_SUPPORTED
+/* Convert a palette image to an rgb image. This necessarily converts the tRNS
+ * chunk at the same time, because the tRNS will be in palette form. The way
+ * palette validation works means that the original palette is never updated,
+ * instead the image_pixel value from the row contains the RGB of the
+ * corresponding palette entry and *this* is updated. Consequently this routine
+ * only needs to change the colour type information.
+ */
+static void
+image_pixel_convert_PLTE(image_pixel *this)
+{
+ if (this->colour_type == PNG_COLOR_TYPE_PALETTE)
+ {
+ if (this->have_tRNS)
+ {
+ this->colour_type = PNG_COLOR_TYPE_RGB_ALPHA;
+ this->have_tRNS = 0;
+ }
+ else
+ this->colour_type = PNG_COLOR_TYPE_RGB;
+
+ /* The bit depth of the row changes at this point too (notice that this is
+ * the row format, not the sample depth, which is separate.)
+ */
+ this->bit_depth = 8;
+ }
+}
+
+/* Add an alpha channel; this will import the tRNS information because tRNS is
+ * not valid in an alpha image. The bit depth will invariably be set to at
+ * least 8 prior to 1.7.0. Palette images will be converted to alpha (using
+ * the above API). With png_set_background the alpha channel is never expanded
+ * but this routine is used by pngvalid to simplify code; 'for_background'
+ * records this.
+ */
+static void
+image_pixel_add_alpha(image_pixel *this, const standard_display *display,
+ int for_background)
+{
+ if (this->colour_type == PNG_COLOR_TYPE_PALETTE)
+ image_pixel_convert_PLTE(this);
+
+ if ((this->colour_type & PNG_COLOR_MASK_ALPHA) == 0)
+ {
+ if (this->colour_type == PNG_COLOR_TYPE_GRAY)
+ {
+# if PNG_LIBPNG_VER < 10700
+ if (!for_background && this->bit_depth < 8)
+ this->bit_depth = this->sample_depth = 8;
+# endif
+
+ if (this->have_tRNS)
+ {
+ /* After 1.7 the expansion of bit depth only happens if there is a
+ * tRNS chunk to expand at this point.
+ */
+# if PNG_LIBPNG_VER >= 10700
+ if (!for_background && this->bit_depth < 8)
+ this->bit_depth = this->sample_depth = 8;
+# endif
+
+ this->have_tRNS = 0;
+
+ /* Check the input, original, channel value here against the
+ * original tRNS gray chunk valie.
+ */
+ if (this->red == display->transparent.red)
+ this->alphaf = 0;
+ else
+ this->alphaf = 1;
+ }
+ else
+ this->alphaf = 1;
+
+ this->colour_type = PNG_COLOR_TYPE_GRAY_ALPHA;
+ }
+
+ else if (this->colour_type == PNG_COLOR_TYPE_RGB)
+ {
+ if (this->have_tRNS)
+ {
+ this->have_tRNS = 0;
+
+ /* Again, check the exact input values, not the current transformed
+ * value!
+ */
+ if (this->red == display->transparent.red &&
+ this->green == display->transparent.green &&
+ this->blue == display->transparent.blue)
+ this->alphaf = 0;
+ else
+ this->alphaf = 1;
+ }
+ else
+ this->alphaf = 1;
+
+ this->colour_type = PNG_COLOR_TYPE_RGB_ALPHA;
+ }
+
+ /* The error in the alpha is zero and the sBIT value comes from the
+ * original sBIT data (actually it will always be the original bit depth).
+ */
+ this->alphae = 0;
+ this->alpha_sBIT = display->alpha_sBIT;
+ }
+}
+#endif /* transforms that need image_pixel_add_alpha */
+
+struct transform_display;
+typedef struct image_transform
+{
+ /* The name of this transform: a string. */
+ const char *name;
+
+ /* Each transform can be disabled from the command line: */
+ int enable;
+
+ /* The global list of transforms; read only. */
+ struct image_transform *const list;
+
+ /* The global count of the number of times this transform has been set on an
+ * image.
+ */
+ unsigned int global_use;
+
+ /* The local count of the number of times this transform has been set. */
+ unsigned int local_use;
+
+ /* The next transform in the list, each transform must call its own next
+ * transform after it has processed the pixel successfully.
+ */
+ const struct image_transform *next;
+
+ /* A single transform for the image, expressed as a series of function
+ * callbacks and some space for values.
+ *
+ * First a callback to add any required modifications to the png_modifier;
+ * this gets called just before the modifier is set up for read.
+ */
+ void (*ini)(const struct image_transform *this,
+ struct transform_display *that);
+
+ /* And a callback to set the transform on the current png_read_struct:
+ */
+ void (*set)(const struct image_transform *this,
+ struct transform_display *that, png_structp pp, png_infop pi);
+
+ /* Then a transform that takes an input pixel in one PNG format or another
+ * and modifies it by a pngvalid implementation of the transform (thus
+ * duplicating the libpng intent without, we hope, duplicating the bugs
+ * in the libpng implementation!) The png_structp is solely to allow error
+ * reporting via png_error and png_warning.
+ */
+ void (*mod)(const struct image_transform *this, image_pixel *that,
+ png_const_structp pp, const struct transform_display *display);
+
+ /* Add this transform to the list and return true if the transform is
+ * meaningful for this colour type and bit depth - if false then the
+ * transform should have no effect on the image so there's not a lot of
+ * point running it.
+ */
+ int (*add)(struct image_transform *this,
+ const struct image_transform **that, png_byte colour_type,
+ png_byte bit_depth);
+} image_transform;
+
+typedef struct transform_display
+{
+ standard_display this;
+
+ /* Parameters */
+ png_modifier* pm;
+ const image_transform* transform_list;
+ unsigned int max_gamma_8;
+
+ /* Local variables */
+ png_byte output_colour_type;
+ png_byte output_bit_depth;
+ png_byte unpacked;
+
+ /* Modifications (not necessarily used.) */
+ gama_modification gama_mod;
+ chrm_modification chrm_mod;
+ srgb_modification srgb_mod;
+} transform_display;
+
+/* Set sRGB, cHRM and gAMA transforms as required by the current encoding. */
+static void
+transform_set_encoding(transform_display *this)
+{
+ /* Set up the png_modifier '_current' fields then use these to determine how
+ * to add appropriate chunks.
+ */
+ png_modifier *pm = this->pm;
+
+ modifier_set_encoding(pm);
+
+ if (modifier_color_encoding_is_set(pm))
+ {
+ if (modifier_color_encoding_is_sRGB(pm))
+ srgb_modification_init(&this->srgb_mod, pm, PNG_sRGB_INTENT_ABSOLUTE);
+
+ else
+ {
+ /* Set gAMA and cHRM separately. */
+ gama_modification_init(&this->gama_mod, pm, pm->current_gamma);
+
+ if (pm->current_encoding != 0)
+ chrm_modification_init(&this->chrm_mod, pm, pm->current_encoding);
+ }
+ }
+}
+
+/* Three functions to end the list: */
+static void
+image_transform_ini_end(const image_transform *this,
+ transform_display *that)
+{
+ UNUSED(this)
+ UNUSED(that)
+}
+
+static void
+image_transform_set_end(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ UNUSED(this)
+ UNUSED(that)
+ UNUSED(pp)
+ UNUSED(pi)
+}
+
+/* At the end of the list recalculate the output image pixel value from the
+ * double precision values set up by the preceding 'mod' calls:
+ */
+static unsigned int
+sample_scale(double sample_value, unsigned int scale)
+{
+ sample_value = floor(sample_value * scale + .5);
+
+ /* Return NaN as 0: */
+ if (!(sample_value > 0))
+ sample_value = 0;
+ else if (sample_value > scale)
+ sample_value = scale;
+
+ return (unsigned int)sample_value;
+}
+
+static void
+image_transform_mod_end(const image_transform *this, image_pixel *that,
+ png_const_structp pp, const transform_display *display)
+{
+ const unsigned int scale = (1U<<that->sample_depth)-1;
+ const int sig_bits = that->sig_bits;
+
+ UNUSED(this)
+ UNUSED(pp)
+ UNUSED(display)
+
+ /* At the end recalculate the digitized red green and blue values according
+ * to the current sample_depth of the pixel.
+ *
+ * The sample value is simply scaled to the maximum, checking for over
+ * and underflow (which can both happen for some image transforms,
+ * including simple size scaling, though libpng doesn't do that at present.
+ */
+ that->red = sample_scale(that->redf, scale);
+
+ /* This is a bit bogus; really the above calculation should use the red_sBIT
+ * value, not sample_depth, but because libpng does png_set_shift by just
+ * shifting the bits we get errors if we don't do it the same way.
+ */
+ if (sig_bits && that->red_sBIT < that->sample_depth)
+ that->red >>= that->sample_depth - that->red_sBIT;
+
+ /* The error value is increased, at the end, according to the lowest sBIT
+ * value seen. Common sense tells us that the intermediate integer
+ * representations are no more accurate than +/- 0.5 in the integral values,
+ * the sBIT allows the implementation to be worse than this. In addition the
+ * PNG specification actually permits any error within the range (-1..+1),
+ * but that is ignored here. Instead the final digitized value is compared,
+ * below to the digitized value of the error limits - this has the net effect
+ * of allowing (almost) +/-1 in the output value. It's difficult to see how
+ * any algorithm that digitizes intermediate results can be more accurate.
+ */
+ that->rede += 1./(2*((1U<<that->red_sBIT)-1));
+
+ if (that->colour_type & PNG_COLOR_MASK_COLOR)
+ {
+ that->green = sample_scale(that->greenf, scale);
+ if (sig_bits && that->green_sBIT < that->sample_depth)
+ that->green >>= that->sample_depth - that->green_sBIT;
+
+ that->blue = sample_scale(that->bluef, scale);
+ if (sig_bits && that->blue_sBIT < that->sample_depth)
+ that->blue >>= that->sample_depth - that->blue_sBIT;
+
+ that->greene += 1./(2*((1U<<that->green_sBIT)-1));
+ that->bluee += 1./(2*((1U<<that->blue_sBIT)-1));
+ }
+ else
+ {
+ that->blue = that->green = that->red;
+ that->bluef = that->greenf = that->redf;
+ that->bluee = that->greene = that->rede;
+ }
+
+ if ((that->colour_type & PNG_COLOR_MASK_ALPHA) ||
+ that->colour_type == PNG_COLOR_TYPE_PALETTE)
+ {
+ that->alpha = sample_scale(that->alphaf, scale);
+ that->alphae += 1./(2*((1U<<that->alpha_sBIT)-1));
+ }
+ else
+ {
+ that->alpha = scale; /* opaque */
+ that->alphaf = 1; /* Override this. */
+ that->alphae = 0; /* It's exact ;-) */
+ }
+
+ if (sig_bits && that->alpha_sBIT < that->sample_depth)
+ that->alpha >>= that->sample_depth - that->alpha_sBIT;
+}
+
+/* Static 'end' structure: */
+static image_transform image_transform_end =
+{
+ "(end)", /* name */
+ 1, /* enable */
+ 0, /* list */
+ 0, /* global_use */
+ 0, /* local_use */
+ 0, /* next */
+ image_transform_ini_end,
+ image_transform_set_end,
+ image_transform_mod_end,
+ 0 /* never called, I want it to crash if it is! */
+};
+
+/* Reader callbacks and implementations, where they differ from the standard
+ * ones.
+ */
+static void
+transform_display_init(transform_display *dp, png_modifier *pm, png_uint_32 id,
+ const image_transform *transform_list)
+{
+ memset(dp, 0, sizeof *dp);
+
+ /* Standard fields */
+ standard_display_init(&dp->this, &pm->this, id, do_read_interlace,
+ pm->use_update_info);
+
+ /* Parameter fields */
+ dp->pm = pm;
+ dp->transform_list = transform_list;
+ dp->max_gamma_8 = 16;
+
+ /* Local variable fields */
+ dp->output_colour_type = 255; /* invalid */
+ dp->output_bit_depth = 255; /* invalid */
+ dp->unpacked = 0; /* not unpacked */
+}
+
+static void
+transform_info_imp(transform_display *dp, png_structp pp, png_infop pi)
+{
+ /* Reuse the standard stuff as appropriate. */
+ standard_info_part1(&dp->this, pp, pi);
+
+ /* Now set the list of transforms. */
+ dp->transform_list->set(dp->transform_list, dp, pp, pi);
+
+ /* Update the info structure for these transforms: */
+ {
+ int i = dp->this.use_update_info;
+ /* Always do one call, even if use_update_info is 0. */
+ do
+ png_read_update_info(pp, pi);
+ while (--i > 0);
+ }
+
+ /* And get the output information into the standard_display */
+ standard_info_part2(&dp->this, pp, pi, 1/*images*/);
+
+ /* Plus the extra stuff we need for the transform tests: */
+ dp->output_colour_type = png_get_color_type(pp, pi);
+ dp->output_bit_depth = png_get_bit_depth(pp, pi);
+
+ /* If png_set_filler is in action then fake the output color type to include
+ * an alpha channel where appropriate.
+ */
+ if (dp->output_bit_depth >= 8 &&
+ (dp->output_colour_type == PNG_COLOR_TYPE_RGB ||
+ dp->output_colour_type == PNG_COLOR_TYPE_GRAY) && dp->this.filler)
+ dp->output_colour_type |= 4;
+
+ /* Validate the combination of colour type and bit depth that we are getting
+ * out of libpng; the semantics of something not in the PNG spec are, at
+ * best, unclear.
+ */
+ switch (dp->output_colour_type)
+ {
+ case PNG_COLOR_TYPE_PALETTE:
+ if (dp->output_bit_depth > 8) goto error;
+ /*FALL THROUGH*/
+ case PNG_COLOR_TYPE_GRAY:
+ if (dp->output_bit_depth == 1 || dp->output_bit_depth == 2 ||
+ dp->output_bit_depth == 4)
+ break;
+ /*FALL THROUGH*/
+ default:
+ if (dp->output_bit_depth == 8 || dp->output_bit_depth == 16)
+ break;
+ /*FALL THROUGH*/
+ error:
+ {
+ char message[128];
+ size_t pos;
+
+ pos = safecat(message, sizeof message, 0,
+ "invalid final bit depth: colour type(");
+ pos = safecatn(message, sizeof message, pos, dp->output_colour_type);
+ pos = safecat(message, sizeof message, pos, ") with bit depth: ");
+ pos = safecatn(message, sizeof message, pos, dp->output_bit_depth);
+
+ png_error(pp, message);
+ }
+ }
+
+ /* Use a test pixel to check that the output agrees with what we expect -
+ * this avoids running the whole test if the output is unexpected. This also
+ * checks for internal errors.
+ */
+ {
+ image_pixel test_pixel;
+
+ memset(&test_pixel, 0, sizeof test_pixel);
+ test_pixel.colour_type = dp->this.colour_type; /* input */
+ test_pixel.bit_depth = dp->this.bit_depth;
+ if (test_pixel.colour_type == PNG_COLOR_TYPE_PALETTE)
+ test_pixel.sample_depth = 8;
+ else
+ test_pixel.sample_depth = test_pixel.bit_depth;
+ /* Don't need sBIT here, but it must be set to non-zero to avoid
+ * arithmetic overflows.
+ */
+ test_pixel.have_tRNS = dp->this.is_transparent != 0;
+ test_pixel.red_sBIT = test_pixel.green_sBIT = test_pixel.blue_sBIT =
+ test_pixel.alpha_sBIT = test_pixel.sample_depth;
+
+ dp->transform_list->mod(dp->transform_list, &test_pixel, pp, dp);
+
+ if (test_pixel.colour_type != dp->output_colour_type)
+ {
+ char message[128];
+ size_t pos = safecat(message, sizeof message, 0, "colour type ");
+
+ pos = safecatn(message, sizeof message, pos, dp->output_colour_type);
+ pos = safecat(message, sizeof message, pos, " expected ");
+ pos = safecatn(message, sizeof message, pos, test_pixel.colour_type);
+
+ png_error(pp, message);
+ }
+
+ if (test_pixel.bit_depth != dp->output_bit_depth)
+ {
+ char message[128];
+ size_t pos = safecat(message, sizeof message, 0, "bit depth ");
+
+ pos = safecatn(message, sizeof message, pos, dp->output_bit_depth);
+ pos = safecat(message, sizeof message, pos, " expected ");
+ pos = safecatn(message, sizeof message, pos, test_pixel.bit_depth);
+
+ png_error(pp, message);
+ }
+
+ /* If both bit depth and colour type are correct check the sample depth.
+ */
+ if (test_pixel.colour_type == PNG_COLOR_TYPE_PALETTE &&
+ test_pixel.sample_depth != 8) /* oops - internal error! */
+ png_error(pp, "pngvalid: internal: palette sample depth not 8");
+ else if (dp->unpacked && test_pixel.bit_depth != 8)
+ png_error(pp, "pngvalid: internal: bad unpacked pixel depth");
+ else if (!dp->unpacked && test_pixel.colour_type != PNG_COLOR_TYPE_PALETTE
+ && test_pixel.bit_depth != test_pixel.sample_depth)
+ {
+ char message[128];
+ size_t pos = safecat(message, sizeof message, 0,
+ "internal: sample depth ");
+
+ /* Because unless something has set 'unpacked' or the image is palette
+ * mapped we expect the transform to keep sample depth and bit depth
+ * the same.
+ */
+ pos = safecatn(message, sizeof message, pos, test_pixel.sample_depth);
+ pos = safecat(message, sizeof message, pos, " expected ");
+ pos = safecatn(message, sizeof message, pos, test_pixel.bit_depth);
+
+ png_error(pp, message);
+ }
+ else if (test_pixel.bit_depth != dp->output_bit_depth)
+ {
+ /* This could be a libpng error too; libpng has not produced what we
+ * expect for the output bit depth.
+ */
+ char message[128];
+ size_t pos = safecat(message, sizeof message, 0,
+ "internal: bit depth ");
+
+ pos = safecatn(message, sizeof message, pos, dp->output_bit_depth);
+ pos = safecat(message, sizeof message, pos, " expected ");
+ pos = safecatn(message, sizeof message, pos, test_pixel.bit_depth);
+
+ png_error(pp, message);
+ }
+ }
+}
+
+static void PNGCBAPI
+transform_info(png_structp pp, png_infop pi)
+{
+ transform_info_imp(voidcast(transform_display*, png_get_progressive_ptr(pp)),
+ pp, pi);
+}
+
+static void
+transform_range_check(png_const_structp pp, unsigned int r, unsigned int g,
+ unsigned int b, unsigned int a, unsigned int in_digitized, double in,
+ unsigned int out, png_byte sample_depth, double err, double limit,
+ const char *name, double digitization_error)
+{
+ /* Compare the scaled, digitzed, values of our local calculation (in+-err)
+ * with the digitized values libpng produced; 'sample_depth' is the actual
+ * digitization depth of the libpng output colors (the bit depth except for
+ * palette images where it is always 8.) The check on 'err' is to detect
+ * internal errors in pngvalid itself.
+ */
+ unsigned int max = (1U<<sample_depth)-1;
+ double in_min = ceil((in-err)*max - digitization_error);
+ double in_max = floor((in+err)*max + digitization_error);
+ if (err > limit || !(out >= in_min && out <= in_max))
+ {
+ char message[256];
+ size_t pos;
+
+ pos = safecat(message, sizeof message, 0, name);
+ pos = safecat(message, sizeof message, pos, " output value error: rgba(");
+ pos = safecatn(message, sizeof message, pos, r);
+ pos = safecat(message, sizeof message, pos, ",");
+ pos = safecatn(message, sizeof message, pos, g);
+ pos = safecat(message, sizeof message, pos, ",");
+ pos = safecatn(message, sizeof message, pos, b);
+ pos = safecat(message, sizeof message, pos, ",");
+ pos = safecatn(message, sizeof message, pos, a);
+ pos = safecat(message, sizeof message, pos, "): ");
+ pos = safecatn(message, sizeof message, pos, out);
+ pos = safecat(message, sizeof message, pos, " expected: ");
+ pos = safecatn(message, sizeof message, pos, in_digitized);
+ pos = safecat(message, sizeof message, pos, " (");
+ pos = safecatd(message, sizeof message, pos, (in-err)*max, 3);
+ pos = safecat(message, sizeof message, pos, "..");
+ pos = safecatd(message, sizeof message, pos, (in+err)*max, 3);
+ pos = safecat(message, sizeof message, pos, ")");
+
+ png_error(pp, message);
+ }
+}
+
+static void
+transform_image_validate(transform_display *dp, png_const_structp pp,
+ png_infop pi)
+{
+ /* Constants for the loop below: */
+ const png_store* const ps = dp->this.ps;
+ const png_byte in_ct = dp->this.colour_type;
+ const png_byte in_bd = dp->this.bit_depth;
+ const png_uint_32 w = dp->this.w;
+ const png_uint_32 h = dp->this.h;
+ const png_byte out_ct = dp->output_colour_type;
+ const png_byte out_bd = dp->output_bit_depth;
+ const png_byte sample_depth = (png_byte)(out_ct ==
+ PNG_COLOR_TYPE_PALETTE ? 8 : out_bd);
+ const png_byte red_sBIT = dp->this.red_sBIT;
+ const png_byte green_sBIT = dp->this.green_sBIT;
+ const png_byte blue_sBIT = dp->this.blue_sBIT;
+ const png_byte alpha_sBIT = dp->this.alpha_sBIT;
+ const int have_tRNS = dp->this.is_transparent;
+ double digitization_error;
+
+ store_palette out_palette;
+ png_uint_32 y;
+
+ UNUSED(pi)
+
+ /* Check for row overwrite errors */
+ store_image_check(dp->this.ps, pp, 0);
+
+ /* Read the palette corresponding to the output if the output colour type
+ * indicates a palette, othewise set out_palette to garbage.
+ */
+ if (out_ct == PNG_COLOR_TYPE_PALETTE)
+ {
+ /* Validate that the palette count itself has not changed - this is not
+ * expected.
+ */
+ int npalette = (-1);
+
+ (void)read_palette(out_palette, &npalette, pp, pi);
+ if (npalette != dp->this.npalette)
+ png_error(pp, "unexpected change in palette size");
+
+ digitization_error = .5;
+ }
+ else
+ {
+ png_byte in_sample_depth;
+
+ memset(out_palette, 0x5e, sizeof out_palette);
+
+ /* use-input-precision means assume that if the input has 8 bit (or less)
+ * samples and the output has 16 bit samples the calculations will be done
+ * with 8 bit precision, not 16.
+ */
+ if (in_ct == PNG_COLOR_TYPE_PALETTE || in_bd < 16)
+ in_sample_depth = 8;
+ else
+ in_sample_depth = in_bd;
+
+ if (sample_depth != 16 || in_sample_depth > 8 ||
+ !dp->pm->calculations_use_input_precision)
+ digitization_error = .5;
+
+ /* Else calculations are at 8 bit precision, and the output actually
+ * consists of scaled 8-bit values, so scale .5 in 8 bits to the 16 bits:
+ */
+ else
+ digitization_error = .5 * 257;
+ }
+
+ for (y=0; y<h; ++y)
+ {
+ png_const_bytep const pRow = store_image_row(ps, pp, 0, y);
+ png_uint_32 x;
+
+ /* The original, standard, row pre-transforms. */
+ png_byte std[STANDARD_ROWMAX];
+
+ transform_row(pp, std, in_ct, in_bd, y);
+
+ /* Go through each original pixel transforming it and comparing with what
+ * libpng did to the same pixel.
+ */
+ for (x=0; x<w; ++x)
+ {
+ image_pixel in_pixel, out_pixel;
+ unsigned int r, g, b, a;
+
+ /* Find out what we think the pixel should be: */
+ image_pixel_init(&in_pixel, std, in_ct, in_bd, x, dp->this.palette,
+ NULL);
+
+ in_pixel.red_sBIT = red_sBIT;
+ in_pixel.green_sBIT = green_sBIT;
+ in_pixel.blue_sBIT = blue_sBIT;
+ in_pixel.alpha_sBIT = alpha_sBIT;
+ in_pixel.have_tRNS = have_tRNS != 0;
+
+ /* For error detection, below. */
+ r = in_pixel.red;
+ g = in_pixel.green;
+ b = in_pixel.blue;
+ a = in_pixel.alpha;
+
+ /* This applies the transforms to the input data, including output
+ * format operations which must be used when reading the output
+ * pixel that libpng produces.
+ */
+ dp->transform_list->mod(dp->transform_list, &in_pixel, pp, dp);
+
+ /* Read the output pixel and compare it to what we got, we don't
+ * use the error field here, so no need to update sBIT. in_pixel
+ * says whether we expect libpng to change the output format.
+ */
+ image_pixel_init(&out_pixel, pRow, out_ct, out_bd, x, out_palette,
+ &in_pixel);
+
+ /* We don't expect changes to the index here even if the bit depth is
+ * changed.
+ */
+ if (in_ct == PNG_COLOR_TYPE_PALETTE &&
+ out_ct == PNG_COLOR_TYPE_PALETTE)
+ {
+ if (in_pixel.palette_index != out_pixel.palette_index)
+ png_error(pp, "unexpected transformed palette index");
+ }
+
+ /* Check the colours for palette images too - in fact the palette could
+ * be separately verified itself in most cases.
+ */
+ if (in_pixel.red != out_pixel.red)
+ transform_range_check(pp, r, g, b, a, in_pixel.red, in_pixel.redf,
+ out_pixel.red, sample_depth, in_pixel.rede,
+ dp->pm->limit + 1./(2*((1U<<in_pixel.red_sBIT)-1)), "red/gray",
+ digitization_error);
+
+ if ((out_ct & PNG_COLOR_MASK_COLOR) != 0 &&
+ in_pixel.green != out_pixel.green)
+ transform_range_check(pp, r, g, b, a, in_pixel.green,
+ in_pixel.greenf, out_pixel.green, sample_depth, in_pixel.greene,
+ dp->pm->limit + 1./(2*((1U<<in_pixel.green_sBIT)-1)), "green",
+ digitization_error);
+
+ if ((out_ct & PNG_COLOR_MASK_COLOR) != 0 &&
+ in_pixel.blue != out_pixel.blue)
+ transform_range_check(pp, r, g, b, a, in_pixel.blue, in_pixel.bluef,
+ out_pixel.blue, sample_depth, in_pixel.bluee,
+ dp->pm->limit + 1./(2*((1U<<in_pixel.blue_sBIT)-1)), "blue",
+ digitization_error);
+
+ if ((out_ct & PNG_COLOR_MASK_ALPHA) != 0 &&
+ in_pixel.alpha != out_pixel.alpha)
+ transform_range_check(pp, r, g, b, a, in_pixel.alpha,
+ in_pixel.alphaf, out_pixel.alpha, sample_depth, in_pixel.alphae,
+ dp->pm->limit + 1./(2*((1U<<in_pixel.alpha_sBIT)-1)), "alpha",
+ digitization_error);
+ } /* pixel (x) loop */
+ } /* row (y) loop */
+
+ /* Record that something was actually checked to avoid a false positive. */
+ dp->this.ps->validated = 1;
+}
+
+static void PNGCBAPI
+transform_end(png_structp ppIn, png_infop pi)
+{
+ png_const_structp pp = ppIn;
+ transform_display *dp = voidcast(transform_display*,
+ png_get_progressive_ptr(pp));
+
+ if (!dp->this.speed)
+ transform_image_validate(dp, pp, pi);
+ else
+ dp->this.ps->validated = 1;
+}
+
+/* A single test run. */
+static void
+transform_test(png_modifier *pmIn, const png_uint_32 idIn,
+ const image_transform* transform_listIn, const char * const name)
+{
+ transform_display d;
+ context(&pmIn->this, fault);
+
+ transform_display_init(&d, pmIn, idIn, transform_listIn);
+
+ Try
+ {
+ size_t pos = 0;
+ png_structp pp;
+ png_infop pi;
+ char full_name[256];
+
+ /* Make sure the encoding fields are correct and enter the required
+ * modifications.
+ */
+ transform_set_encoding(&d);
+
+ /* Add any modifications required by the transform list. */
+ d.transform_list->ini(d.transform_list, &d);
+
+ /* Add the color space information, if any, to the name. */
+ pos = safecat(full_name, sizeof full_name, pos, name);
+ pos = safecat_current_encoding(full_name, sizeof full_name, pos, d.pm);
+
+ /* Get a png_struct for reading the image. */
+ pp = set_modifier_for_read(d.pm, &pi, d.this.id, full_name);
+ standard_palette_init(&d.this);
+
+# if 0
+ /* Logging (debugging only) */
+ {
+ char buffer[256];
+
+ (void)store_message(&d.pm->this, pp, buffer, sizeof buffer, 0,
+ "running test");
+
+ fprintf(stderr, "%s\n", buffer);
+ }
+# endif
+
+ /* Introduce the correct read function. */
+ if (d.pm->this.progressive)
+ {
+ /* Share the row function with the standard implementation. */
+ png_set_progressive_read_fn(pp, &d, transform_info, progressive_row,
+ transform_end);
+
+ /* Now feed data into the reader until we reach the end: */
+ modifier_progressive_read(d.pm, pp, pi);
+ }
+ else
+ {
+ /* modifier_read expects a png_modifier* */
+ png_set_read_fn(pp, d.pm, modifier_read);
+
+ /* Check the header values: */
+ png_read_info(pp, pi);
+
+ /* Process the 'info' requirements. Only one image is generated */
+ transform_info_imp(&d, pp, pi);
+
+ sequential_row(&d.this, pp, pi, -1, 0);
+
+ if (!d.this.speed)
+ transform_image_validate(&d, pp, pi);
+ else
+ d.this.ps->validated = 1;
+ }
+
+ modifier_reset(d.pm);
+ }
+
+ Catch(fault)
+ {
+ modifier_reset(voidcast(png_modifier*,(void*)fault));
+ }
+}
+
+/* The transforms: */
+#define ITSTRUCT(name) image_transform_##name
+#define ITDATA(name) image_transform_data_##name
+#define image_transform_ini image_transform_default_ini
+#define IT(name)\
+static image_transform ITSTRUCT(name) =\
+{\
+ #name,\
+ 1, /*enable*/\
+ &PT, /*list*/\
+ 0, /*global_use*/\
+ 0, /*local_use*/\
+ 0, /*next*/\
+ image_transform_ini,\
+ image_transform_png_set_##name##_set,\
+ image_transform_png_set_##name##_mod,\
+ image_transform_png_set_##name##_add\
+}
+#define PT ITSTRUCT(end) /* stores the previous transform */
+
+/* To save code: */
+extern void image_transform_default_ini(const image_transform *this,
+ transform_display *that); /* silence GCC warnings */
+
+void /* private, but almost always needed */
+image_transform_default_ini(const image_transform *this,
+ transform_display *that)
+{
+ this->next->ini(this->next, that);
+}
+
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
+static int
+image_transform_default_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ UNUSED(colour_type)
+ UNUSED(bit_depth)
+
+ this->next = *that;
+ *that = this;
+
+ return 1;
+}
+#endif
+
+#ifdef PNG_READ_EXPAND_SUPPORTED
+/* png_set_palette_to_rgb */
+static void
+image_transform_png_set_palette_to_rgb_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ png_set_palette_to_rgb(pp);
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_palette_to_rgb_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
+ image_pixel_convert_PLTE(that);
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_palette_to_rgb_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ UNUSED(bit_depth)
+
+ this->next = *that;
+ *that = this;
+
+ return colour_type == PNG_COLOR_TYPE_PALETTE;
+}
+
+IT(palette_to_rgb);
+#undef PT
+#define PT ITSTRUCT(palette_to_rgb)
+#endif /* PNG_READ_EXPAND_SUPPORTED */
+
+#ifdef PNG_READ_EXPAND_SUPPORTED
+/* png_set_tRNS_to_alpha */
+static void
+image_transform_png_set_tRNS_to_alpha_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ png_set_tRNS_to_alpha(pp);
+
+ /* If there was a tRNS chunk that would get expanded and add an alpha
+ * channel is_transparent must be updated:
+ */
+ if (that->this.has_tRNS)
+ that->this.is_transparent = 1;
+
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_tRNS_to_alpha_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+#if PNG_LIBPNG_VER < 10700
+ /* LIBPNG BUG: this always forces palette images to RGB. */
+ if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
+ image_pixel_convert_PLTE(that);
+#endif
+
+ /* This effectively does an 'expand' only if there is some transparency to
+ * convert to an alpha channel.
+ */
+ if (that->have_tRNS)
+# if PNG_LIBPNG_VER >= 10700
+ if (that->colour_type != PNG_COLOR_TYPE_PALETTE &&
+ (that->colour_type & PNG_COLOR_MASK_ALPHA) == 0)
+# endif
+ image_pixel_add_alpha(that, &display->this, 0/*!for background*/);
+
+#if PNG_LIBPNG_VER < 10700
+ /* LIBPNG BUG: otherwise libpng still expands to 8 bits! */
+ else
+ {
+ if (that->bit_depth < 8)
+ that->bit_depth =8;
+ if (that->sample_depth < 8)
+ that->sample_depth = 8;
+ }
+#endif
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_tRNS_to_alpha_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ UNUSED(bit_depth)
+
+ this->next = *that;
+ *that = this;
+
+ /* We don't know yet whether there will be a tRNS chunk, but we know that
+ * this transformation should do nothing if there already is an alpha
+ * channel. In addition, after the bug fix in 1.7.0, there is no longer
+ * any action on a palette image.
+ */
+ return
+# if PNG_LIBPNG_VER >= 10700
+ colour_type != PNG_COLOR_TYPE_PALETTE &&
+# endif
+ (colour_type & PNG_COLOR_MASK_ALPHA) == 0;
+}
+
+IT(tRNS_to_alpha);
+#undef PT
+#define PT ITSTRUCT(tRNS_to_alpha)
+#endif /* PNG_READ_EXPAND_SUPPORTED */
+
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
+/* png_set_gray_to_rgb */
+static void
+image_transform_png_set_gray_to_rgb_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ png_set_gray_to_rgb(pp);
+ /* NOTE: this doesn't result in tRNS expansion. */
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_gray_to_rgb_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ /* NOTE: we can actually pend the tRNS processing at this point because we
+ * can correctly recognize the original pixel value even though we have
+ * mapped the one gray channel to the three RGB ones, but in fact libpng
+ * doesn't do this, so we don't either.
+ */
+ if ((that->colour_type & PNG_COLOR_MASK_COLOR) == 0 && that->have_tRNS)
+ image_pixel_add_alpha(that, &display->this, 0/*!for background*/);
+
+ /* Simply expand the bit depth and alter the colour type as required. */
+ if (that->colour_type == PNG_COLOR_TYPE_GRAY)
+ {
+ /* RGB images have a bit depth at least equal to '8' */
+ if (that->bit_depth < 8)
+ that->sample_depth = that->bit_depth = 8;
+
+ /* And just changing the colour type works here because the green and blue
+ * channels are being maintained in lock-step with the red/gray:
+ */
+ that->colour_type = PNG_COLOR_TYPE_RGB;
+ }
+
+ else if (that->colour_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+ that->colour_type = PNG_COLOR_TYPE_RGB_ALPHA;
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_gray_to_rgb_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ UNUSED(bit_depth)
+
+ this->next = *that;
+ *that = this;
+
+ return (colour_type & PNG_COLOR_MASK_COLOR) == 0;
+}
+
+IT(gray_to_rgb);
+#undef PT
+#define PT ITSTRUCT(gray_to_rgb)
+#endif /* PNG_READ_GRAY_TO_RGB_SUPPORTED */
+
+#ifdef PNG_READ_EXPAND_SUPPORTED
+/* png_set_expand */
+static void
+image_transform_png_set_expand_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ png_set_expand(pp);
+
+ if (that->this.has_tRNS)
+ that->this.is_transparent = 1;
+
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_expand_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ /* The general expand case depends on what the colour type is: */
+ if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
+ image_pixel_convert_PLTE(that);
+ else if (that->bit_depth < 8) /* grayscale */
+ that->sample_depth = that->bit_depth = 8;
+
+ if (that->have_tRNS)
+ image_pixel_add_alpha(that, &display->this, 0/*!for background*/);
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_expand_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ UNUSED(bit_depth)
+
+ this->next = *that;
+ *that = this;
+
+ /* 'expand' should do nothing for RGBA or GA input - no tRNS and the bit
+ * depth is at least 8 already.
+ */
+ return (colour_type & PNG_COLOR_MASK_ALPHA) == 0;
+}
+
+IT(expand);
+#undef PT
+#define PT ITSTRUCT(expand)
+#endif /* PNG_READ_EXPAND_SUPPORTED */
+
+#ifdef PNG_READ_EXPAND_SUPPORTED
+/* png_set_expand_gray_1_2_4_to_8
+ * Pre 1.7.0 LIBPNG BUG: this just does an 'expand'
+ */
+static void
+image_transform_png_set_expand_gray_1_2_4_to_8_set(
+ const image_transform *this, transform_display *that, png_structp pp,
+ png_infop pi)
+{
+ png_set_expand_gray_1_2_4_to_8(pp);
+ /* NOTE: don't expect this to expand tRNS */
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_expand_gray_1_2_4_to_8_mod(
+ const image_transform *this, image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+#if PNG_LIBPNG_VER < 10700
+ image_transform_png_set_expand_mod(this, that, pp, display);
+#else
+ /* Only expand grayscale of bit depth less than 8: */
+ if (that->colour_type == PNG_COLOR_TYPE_GRAY &&
+ that->bit_depth < 8)
+ that->sample_depth = that->bit_depth = 8;
+
+ this->next->mod(this->next, that, pp, display);
+#endif /* 1.7 or later */
+}
+
+static int
+image_transform_png_set_expand_gray_1_2_4_to_8_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+#if PNG_LIBPNG_VER < 10700
+ return image_transform_png_set_expand_add(this, that, colour_type,
+ bit_depth);
+#else
+ UNUSED(bit_depth)
+
+ this->next = *that;
+ *that = this;
+
+ /* This should do nothing unless the color type is gray and the bit depth is
+ * less than 8:
+ */
+ return colour_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8;
+#endif /* 1.7 or later */
+}
+
+IT(expand_gray_1_2_4_to_8);
+#undef PT
+#define PT ITSTRUCT(expand_gray_1_2_4_to_8)
+#endif /* PNG_READ_EXPAND_SUPPORTED */
+
+#ifdef PNG_READ_EXPAND_16_SUPPORTED
+/* png_set_expand_16 */
+static void
+image_transform_png_set_expand_16_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ png_set_expand_16(pp);
+
+ /* NOTE: prior to 1.7 libpng does SET_EXPAND as well, so tRNS is expanded. */
+# if PNG_LIBPNG_VER < 10700
+ if (that->this.has_tRNS)
+ that->this.is_transparent = 1;
+# endif
+
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_expand_16_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ /* Expect expand_16 to expand everything to 16 bits as a result of also
+ * causing 'expand' to happen.
+ */
+ if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
+ image_pixel_convert_PLTE(that);
+
+ if (that->have_tRNS)
+ image_pixel_add_alpha(that, &display->this, 0/*!for background*/);
+
+ if (that->bit_depth < 16)
+ that->sample_depth = that->bit_depth = 16;
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_expand_16_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ UNUSED(colour_type)
+
+ this->next = *that;
+ *that = this;
+
+ /* expand_16 does something unless the bit depth is already 16. */
+ return bit_depth < 16;
+}
+
+IT(expand_16);
+#undef PT
+#define PT ITSTRUCT(expand_16)
+#endif /* PNG_READ_EXPAND_16_SUPPORTED */
+
+#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED /* API added in 1.5.4 */
+/* png_set_scale_16 */
+static void
+image_transform_png_set_scale_16_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ png_set_scale_16(pp);
+# if PNG_LIBPNG_VER < 10700
+ /* libpng will limit the gamma table size: */
+ that->max_gamma_8 = PNG_MAX_GAMMA_8;
+# endif
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_scale_16_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ if (that->bit_depth == 16)
+ {
+ that->sample_depth = that->bit_depth = 8;
+ if (that->red_sBIT > 8) that->red_sBIT = 8;
+ if (that->green_sBIT > 8) that->green_sBIT = 8;
+ if (that->blue_sBIT > 8) that->blue_sBIT = 8;
+ if (that->alpha_sBIT > 8) that->alpha_sBIT = 8;
+ }
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_scale_16_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ UNUSED(colour_type)
+
+ this->next = *that;
+ *that = this;
+
+ return bit_depth > 8;
+}
+
+IT(scale_16);
+#undef PT
+#define PT ITSTRUCT(scale_16)
+#endif /* PNG_READ_SCALE_16_TO_8_SUPPORTED (1.5.4 on) */
+
+#ifdef PNG_READ_16_TO_8_SUPPORTED /* the default before 1.5.4 */
+/* png_set_strip_16 */
+static void
+image_transform_png_set_strip_16_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ png_set_strip_16(pp);
+# if PNG_LIBPNG_VER < 10700
+ /* libpng will limit the gamma table size: */
+ that->max_gamma_8 = PNG_MAX_GAMMA_8;
+# endif
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_strip_16_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ if (that->bit_depth == 16)
+ {
+ that->sample_depth = that->bit_depth = 8;
+ if (that->red_sBIT > 8) that->red_sBIT = 8;
+ if (that->green_sBIT > 8) that->green_sBIT = 8;
+ if (that->blue_sBIT > 8) that->blue_sBIT = 8;
+ if (that->alpha_sBIT > 8) that->alpha_sBIT = 8;
+
+ /* Prior to 1.5.4 png_set_strip_16 would use an 'accurate' method if this
+ * configuration option is set. From 1.5.4 the flag is never set and the
+ * 'scale' API (above) must be used.
+ */
+# ifdef PNG_READ_ACCURATE_SCALE_SUPPORTED
+# if PNG_LIBPNG_VER >= 10504
+# error PNG_READ_ACCURATE_SCALE should not be set
+# endif
+
+ /* The strip 16 algorithm drops the low 8 bits rather than calculating
+ * 1/257, so we need to adjust the permitted errors appropriately:
+ * Notice that this is only relevant prior to the addition of the
+ * png_set_scale_16 API in 1.5.4 (but 1.5.4+ always defines the above!)
+ */
+ {
+ const double d = (255-128.5)/65535;
+ that->rede += d;
+ that->greene += d;
+ that->bluee += d;
+ that->alphae += d;
+ }
+# endif
+ }
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_strip_16_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ UNUSED(colour_type)
+
+ this->next = *that;
+ *that = this;
+
+ return bit_depth > 8;
+}
+
+IT(strip_16);
+#undef PT
+#define PT ITSTRUCT(strip_16)
+#endif /* PNG_READ_16_TO_8_SUPPORTED */
+
+#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
+/* png_set_strip_alpha */
+static void
+image_transform_png_set_strip_alpha_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ png_set_strip_alpha(pp);
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_strip_alpha_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ if (that->colour_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+ that->colour_type = PNG_COLOR_TYPE_GRAY;
+ else if (that->colour_type == PNG_COLOR_TYPE_RGB_ALPHA)
+ that->colour_type = PNG_COLOR_TYPE_RGB;
+
+ that->have_tRNS = 0;
+ that->alphaf = 1;
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_strip_alpha_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ UNUSED(bit_depth)
+
+ this->next = *that;
+ *that = this;
+
+ return (colour_type & PNG_COLOR_MASK_ALPHA) != 0;
+}
+
+IT(strip_alpha);
+#undef PT
+#define PT ITSTRUCT(strip_alpha)
+#endif /* PNG_READ_STRIP_ALPHA_SUPPORTED */
+
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+/* png_set_rgb_to_gray(png_structp, int err_action, double red, double green)
+ * png_set_rgb_to_gray_fixed(png_structp, int err_action, png_fixed_point red,
+ * png_fixed_point green)
+ * png_get_rgb_to_gray_status
+ *
+ * The 'default' test here uses values known to be used inside libpng prior to
+ * 1.7.0:
+ *
+ * red: 6968
+ * green: 23434
+ * blue: 2366
+ *
+ * These values are being retained for compatibility, along with the somewhat
+ * broken truncation calculation in the fast-and-inaccurate code path. Older
+ * versions of libpng will fail the accuracy tests below because they use the
+ * truncation algorithm everywhere.
+ */
+#define data ITDATA(rgb_to_gray)
+static struct
+{
+ double gamma; /* File gamma to use in processing */
+
+ /* The following are the parameters for png_set_rgb_to_gray: */
+# ifdef PNG_FLOATING_POINT_SUPPORTED
+ double red_to_set;
+ double green_to_set;
+# else
+ png_fixed_point red_to_set;
+ png_fixed_point green_to_set;
+# endif
+
+ /* The actual coefficients: */
+ double red_coefficient;
+ double green_coefficient;
+ double blue_coefficient;
+
+ /* Set if the coeefficients have been overridden. */
+ int coefficients_overridden;
+} data;
+
+#undef image_transform_ini
+#define image_transform_ini image_transform_png_set_rgb_to_gray_ini
+static void
+image_transform_png_set_rgb_to_gray_ini(const image_transform *this,
+ transform_display *that)
+{
+ png_modifier *pm = that->pm;
+ const color_encoding *e = pm->current_encoding;
+
+ UNUSED(this)
+
+ /* Since we check the encoding this flag must be set: */
+ pm->test_uses_encoding = 1;
+
+ /* If 'e' is not NULL chromaticity information is present and either a cHRM
+ * or an sRGB chunk will be inserted.
+ */
+ if (e != 0)
+ {
+ /* Coefficients come from the encoding, but may need to be normalized to a
+ * white point Y of 1.0
+ */
+ const double whiteY = e->red.Y + e->green.Y + e->blue.Y;
+
+ data.red_coefficient = e->red.Y;
+ data.green_coefficient = e->green.Y;
+ data.blue_coefficient = e->blue.Y;
+
+ if (whiteY != 1)
+ {
+ data.red_coefficient /= whiteY;
+ data.green_coefficient /= whiteY;
+ data.blue_coefficient /= whiteY;
+ }
+ }
+
+ else
+ {
+ /* The default (built in) coeffcients, as above: */
+# if PNG_LIBPNG_VER < 10700
+ data.red_coefficient = 6968 / 32768.;
+ data.green_coefficient = 23434 / 32768.;
+ data.blue_coefficient = 2366 / 32768.;
+# else
+ data.red_coefficient = .2126;
+ data.green_coefficient = .7152;
+ data.blue_coefficient = .0722;
+# endif
+ }
+
+ data.gamma = pm->current_gamma;
+
+ /* If not set then the calculations assume linear encoding (implicitly): */
+ if (data.gamma == 0)
+ data.gamma = 1;
+
+ /* The arguments to png_set_rgb_to_gray can override the coefficients implied
+ * by the color space encoding. If doing exhaustive checks do the override
+ * in each case, otherwise do it randomly.
+ */
+ if (pm->test_exhaustive)
+ {
+ /* First time in coefficients_overridden is 0, the following sets it to 1,
+ * so repeat if it is set. If a test fails this may mean we subsequently
+ * skip a non-override test, ignore that.
+ */
+ data.coefficients_overridden = !data.coefficients_overridden;
+ pm->repeat = data.coefficients_overridden != 0;
+ }
+
+ else
+ data.coefficients_overridden = random_choice();
+
+ if (data.coefficients_overridden)
+ {
+ /* These values override the color encoding defaults, simply use random
+ * numbers.
+ */
+ png_uint_32 ru;
+ double total;
+
+ RANDOMIZE(ru);
+ data.green_coefficient = total = (ru & 0xffff) / 65535.;
+ ru >>= 16;
+ data.red_coefficient = (1 - total) * (ru & 0xffff) / 65535.;
+ total += data.red_coefficient;
+ data.blue_coefficient = 1 - total;
+
+# ifdef PNG_FLOATING_POINT_SUPPORTED
+ data.red_to_set = data.red_coefficient;
+ data.green_to_set = data.green_coefficient;
+# else
+ data.red_to_set = fix(data.red_coefficient);
+ data.green_to_set = fix(data.green_coefficient);
+# endif
+
+ /* The following just changes the error messages: */
+ pm->encoding_ignored = 1;
+ }
+
+ else
+ {
+ data.red_to_set = -1;
+ data.green_to_set = -1;
+ }
+
+ /* Adjust the error limit in the png_modifier because of the larger errors
+ * produced in the digitization during the gamma handling.
+ */
+ if (data.gamma != 1) /* Use gamma tables */
+ {
+ if (that->this.bit_depth == 16 || pm->assume_16_bit_calculations)
+ {
+ /* The computations have the form:
+ *
+ * r * rc + g * gc + b * bc
+ *
+ * Each component of which is +/-1/65535 from the gamma_to_1 table
+ * lookup, resulting in a base error of +/-6. The gamma_from_1
+ * conversion adds another +/-2 in the 16-bit case and
+ * +/-(1<<(15-PNG_MAX_GAMMA_8)) in the 8-bit case.
+ */
+# if PNG_LIBPNG_VER < 10700
+ if (that->this.bit_depth < 16)
+ that->max_gamma_8 = PNG_MAX_GAMMA_8;
+# endif
+ that->pm->limit += pow(
+ (that->this.bit_depth == 16 || that->max_gamma_8 > 14 ?
+ 8. :
+ 6. + (1<<(15-that->max_gamma_8))
+ )/65535, data.gamma);
+ }
+
+ else
+ {
+ /* Rounding to 8 bits in the linear space causes massive errors which
+ * will trigger the error check in transform_range_check. Fix that
+ * here by taking the gamma encoding into account.
+ *
+ * When DIGITIZE is set because a pre-1.7 version of libpng is being
+ * tested allow a bigger slack.
+ *
+ * NOTE: this magic number was determined by experiment to be about
+ * 1.263. There's no great merit to the value below, however it only
+ * affects the limit used for checking for internal calculation errors,
+ * not the actual limit imposed by pngvalid on the output errors.
+ */
+ that->pm->limit += pow(
+# if DIGITIZE
+ 1.3
+# else
+ 1.0
+# endif
+ /255, data.gamma);
+ }
+ }
+
+ else
+ {
+ /* With no gamma correction a large error comes from the truncation of the
+ * calculation in the 8 bit case, allow for that here.
+ */
+ if (that->this.bit_depth != 16 && !pm->assume_16_bit_calculations)
+ that->pm->limit += 4E-3;
+ }
+}
+
+static void
+image_transform_png_set_rgb_to_gray_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ const int error_action = 1; /* no error, no defines in png.h */
+
+# ifdef PNG_FLOATING_POINT_SUPPORTED
+ png_set_rgb_to_gray(pp, error_action, data.red_to_set, data.green_to_set);
+# else
+ png_set_rgb_to_gray_fixed(pp, error_action, data.red_to_set,
+ data.green_to_set);
+# endif
+
+# ifdef PNG_READ_cHRM_SUPPORTED
+ if (that->pm->current_encoding != 0)
+ {
+ /* We have an encoding so a cHRM chunk may have been set; if so then
+ * check that the libpng APIs give the correct (X,Y,Z) values within
+ * some margin of error for the round trip through the chromaticity
+ * form.
+ */
+# ifdef PNG_FLOATING_POINT_SUPPORTED
+# define API_function png_get_cHRM_XYZ
+# define API_form "FP"
+# define API_type double
+# define API_cvt(x) (x)
+# else
+# define API_function png_get_cHRM_XYZ_fixed
+# define API_form "fixed"
+# define API_type png_fixed_point
+# define API_cvt(x) ((double)(x)/PNG_FP_1)
+# endif
+
+ API_type rX, gX, bX;
+ API_type rY, gY, bY;
+ API_type rZ, gZ, bZ;
+
+ if ((API_function(pp, pi, &rX, &rY, &rZ, &gX, &gY, &gZ, &bX, &bY, &bZ)
+ & PNG_INFO_cHRM) != 0)
+ {
+ double maxe;
+ const char *el;
+ color_encoding e, o;
+
+ /* Expect libpng to return a normalized result, but the original
+ * color space encoding may not be normalized.
+ */
+ modifier_current_encoding(that->pm, &o);
+ normalize_color_encoding(&o);
+
+ /* Sanity check the pngvalid code - the coefficients should match
+ * the normalized Y values of the encoding unless they were
+ * overridden.
+ */
+ if (data.red_to_set == -1 && data.green_to_set == -1 &&
+ (fabs(o.red.Y - data.red_coefficient) > DBL_EPSILON ||
+ fabs(o.green.Y - data.green_coefficient) > DBL_EPSILON ||
+ fabs(o.blue.Y - data.blue_coefficient) > DBL_EPSILON))
+ png_error(pp, "internal pngvalid cHRM coefficient error");
+
+ /* Generate a colour space encoding. */
+ e.gamma = o.gamma; /* not used */
+ e.red.X = API_cvt(rX);
+ e.red.Y = API_cvt(rY);
+ e.red.Z = API_cvt(rZ);
+ e.green.X = API_cvt(gX);
+ e.green.Y = API_cvt(gY);
+ e.green.Z = API_cvt(gZ);
+ e.blue.X = API_cvt(bX);
+ e.blue.Y = API_cvt(bY);
+ e.blue.Z = API_cvt(bZ);
+
+ /* This should match the original one from the png_modifier, within
+ * the range permitted by the libpng fixed point representation.
+ */
+ maxe = 0;
+ el = "-"; /* Set to element name with error */
+
+# define CHECK(col,x)\
+ {\
+ double err = fabs(o.col.x - e.col.x);\
+ if (err > maxe)\
+ {\
+ maxe = err;\
+ el = #col "(" #x ")";\
+ }\
+ }
+
+ CHECK(red,X)
+ CHECK(red,Y)
+ CHECK(red,Z)
+ CHECK(green,X)
+ CHECK(green,Y)
+ CHECK(green,Z)
+ CHECK(blue,X)
+ CHECK(blue,Y)
+ CHECK(blue,Z)
+
+ /* Here in both fixed and floating cases to check the values read
+ * from the cHRm chunk. PNG uses fixed point in the cHRM chunk, so
+ * we can't expect better than +/-.5E-5 on the result, allow 1E-5.
+ */
+ if (maxe >= 1E-5)
+ {
+ size_t pos = 0;
+ char buffer[256];
+
+ pos = safecat(buffer, sizeof buffer, pos, API_form);
+ pos = safecat(buffer, sizeof buffer, pos, " cHRM ");
+ pos = safecat(buffer, sizeof buffer, pos, el);
+ pos = safecat(buffer, sizeof buffer, pos, " error: ");
+ pos = safecatd(buffer, sizeof buffer, pos, maxe, 7);
+ pos = safecat(buffer, sizeof buffer, pos, " ");
+ /* Print the color space without the gamma value: */
+ pos = safecat_color_encoding(buffer, sizeof buffer, pos, &o, 0);
+ pos = safecat(buffer, sizeof buffer, pos, " -> ");
+ pos = safecat_color_encoding(buffer, sizeof buffer, pos, &e, 0);
+
+ png_error(pp, buffer);
+ }
+ }
+ }
+# endif /* READ_cHRM */
+
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_rgb_to_gray_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ if ((that->colour_type & PNG_COLOR_MASK_COLOR) != 0)
+ {
+ double gray, err;
+
+# if PNG_LIBPNG_VER < 10700
+ if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
+ image_pixel_convert_PLTE(that);
+# endif
+
+ /* Image now has RGB channels... */
+# if DIGITIZE
+ {
+ const png_modifier *pm = display->pm;
+ const unsigned int sample_depth = that->sample_depth;
+ const unsigned int calc_depth = (pm->assume_16_bit_calculations ? 16 :
+ sample_depth);
+ const unsigned int gamma_depth =
+ (sample_depth == 16 ?
+ display->max_gamma_8 :
+ (pm->assume_16_bit_calculations ?
+ display->max_gamma_8 :
+ sample_depth));
+ int isgray;
+ double r, g, b;
+ double rlo, rhi, glo, ghi, blo, bhi, graylo, grayhi;
+
+ /* Do this using interval arithmetic, otherwise it is too difficult to
+ * handle the errors correctly.
+ *
+ * To handle the gamma correction work out the upper and lower bounds
+ * of the digitized value. Assume rounding here - normally the values
+ * will be identical after this operation if there is only one
+ * transform, feel free to delete the png_error checks on this below in
+ * the future (this is just me trying to ensure it works!)
+ *
+ * Interval arithmetic is exact, but to implement it it must be
+ * possible to control the floating point implementation rounding mode.
+ * This cannot be done in ANSI-C, so instead I reduce the 'lo' values
+ * by DBL_EPSILON and increase the 'hi' values by the same.
+ */
+# define DD(v,d,r) (digitize(v*(1-DBL_EPSILON), d, r) * (1-DBL_EPSILON))
+# define DU(v,d,r) (digitize(v*(1+DBL_EPSILON), d, r) * (1+DBL_EPSILON))
+
+ r = rlo = rhi = that->redf;
+ rlo -= that->rede;
+ rlo = DD(rlo, calc_depth, 1/*round*/);
+ rhi += that->rede;
+ rhi = DU(rhi, calc_depth, 1/*round*/);
+
+ g = glo = ghi = that->greenf;
+ glo -= that->greene;
+ glo = DD(glo, calc_depth, 1/*round*/);
+ ghi += that->greene;
+ ghi = DU(ghi, calc_depth, 1/*round*/);
+
+ b = blo = bhi = that->bluef;
+ blo -= that->bluee;
+ blo = DD(blo, calc_depth, 1/*round*/);
+ bhi += that->bluee;
+ bhi = DU(bhi, calc_depth, 1/*round*/);
+
+ isgray = r==g && g==b;
+
+ if (data.gamma != 1)
+ {
+ const double power = 1/data.gamma;
+ const double abse = .5/(sample_depth == 16 ? 65535 : 255);
+
+ /* If a gamma calculation is done it is done using lookup tables of
+ * precision gamma_depth, so the already digitized value above may
+ * need to be further digitized here.
+ */
+ if (gamma_depth != calc_depth)
+ {
+ rlo = DD(rlo, gamma_depth, 0/*truncate*/);
+ rhi = DU(rhi, gamma_depth, 0/*truncate*/);
+ glo = DD(glo, gamma_depth, 0/*truncate*/);
+ ghi = DU(ghi, gamma_depth, 0/*truncate*/);
+ blo = DD(blo, gamma_depth, 0/*truncate*/);
+ bhi = DU(bhi, gamma_depth, 0/*truncate*/);
+ }
+
+ /* 'abse' is the error in the gamma table calculation itself. */
+ r = pow(r, power);
+ rlo = DD(pow(rlo, power)-abse, calc_depth, 1);
+ rhi = DU(pow(rhi, power)+abse, calc_depth, 1);
+
+ g = pow(g, power);
+ glo = DD(pow(glo, power)-abse, calc_depth, 1);
+ ghi = DU(pow(ghi, power)+abse, calc_depth, 1);
+
+ b = pow(b, power);
+ blo = DD(pow(blo, power)-abse, calc_depth, 1);
+ bhi = DU(pow(bhi, power)+abse, calc_depth, 1);
+ }
+
+ /* Now calculate the actual gray values. Although the error in the
+ * coefficients depends on whether they were specified on the command
+ * line (in which case truncation to 15 bits happened) or not (rounding
+ * was used) the maxium error in an individual coefficient is always
+ * 2/32768, because even in the rounding case the requirement that
+ * coefficients add up to 32768 can cause a larger rounding error.
+ *
+ * The only time when rounding doesn't occur in 1.5.5 and later is when
+ * the non-gamma code path is used for less than 16 bit data.
+ */
+ gray = r * data.red_coefficient + g * data.green_coefficient +
+ b * data.blue_coefficient;
+
+ {
+ const int do_round = data.gamma != 1 || calc_depth == 16;
+ const double ce = 2. / 32768;
+
+ graylo = DD(rlo * (data.red_coefficient-ce) +
+ glo * (data.green_coefficient-ce) +
+ blo * (data.blue_coefficient-ce), calc_depth, do_round);
+ if (graylo > gray) /* always accept the right answer */
+ graylo = gray;
+
+ grayhi = DU(rhi * (data.red_coefficient+ce) +
+ ghi * (data.green_coefficient+ce) +
+ bhi * (data.blue_coefficient+ce), calc_depth, do_round);
+ if (grayhi < gray)
+ grayhi = gray;
+ }
+
+ /* And invert the gamma. */
+ if (data.gamma != 1)
+ {
+ const double power = data.gamma;
+
+ /* And this happens yet again, shifting the values once more. */
+ if (gamma_depth != sample_depth)
+ {
+ rlo = DD(rlo, gamma_depth, 0/*truncate*/);
+ rhi = DU(rhi, gamma_depth, 0/*truncate*/);
+ glo = DD(glo, gamma_depth, 0/*truncate*/);
+ ghi = DU(ghi, gamma_depth, 0/*truncate*/);
+ blo = DD(blo, gamma_depth, 0/*truncate*/);
+ bhi = DU(bhi, gamma_depth, 0/*truncate*/);
+ }
+
+ gray = pow(gray, power);
+ graylo = DD(pow(graylo, power), sample_depth, 1);
+ grayhi = DU(pow(grayhi, power), sample_depth, 1);
+ }
+
+# undef DD
+# undef DU
+
+ /* Now the error can be calculated.
+ *
+ * If r==g==b because there is no overall gamma correction libpng
+ * currently preserves the original value.
+ */
+ if (isgray)
+ err = (that->rede + that->greene + that->bluee)/3;
+
+ else
+ {
+ err = fabs(grayhi-gray);
+ if (fabs(gray - graylo) > err)
+ err = fabs(graylo-gray);
+
+ /* Check that this worked: */
+ if (err > pm->limit)
+ {
+ size_t pos = 0;
+ char buffer[128];
+
+ pos = safecat(buffer, sizeof buffer, pos, "rgb_to_gray error ");
+ pos = safecatd(buffer, sizeof buffer, pos, err, 6);
+ pos = safecat(buffer, sizeof buffer, pos, " exceeds limit ");
+ pos = safecatd(buffer, sizeof buffer, pos, pm->limit, 6);
+ png_error(pp, buffer);
+ }
+ }
+ }
+# else /* DIGITIZE */
+ {
+ double r = that->redf;
+ double re = that->rede;
+ double g = that->greenf;
+ double ge = that->greene;
+ double b = that->bluef;
+ double be = that->bluee;
+
+# if PNG_LIBPNG_VER < 10700
+ /* The true gray case involves no math in earlier versions (not
+ * true, there was some if gamma correction was happening too.)
+ */
+ if (r == g && r == b)
+ {
+ gray = r;
+ err = re;
+ if (err < ge) err = ge;
+ if (err < be) err = be;
+ }
+
+ else
+# endif /* before 1.7 */
+ if (data.gamma == 1)
+ {
+ /* There is no need to do the conversions to and from linear space,
+ * so the calculation should be a lot more accurate. There is a
+ * built in error in the coefficients because they only have 15 bits
+ * and are adjusted to make sure they add up to 32768. This
+ * involves a integer calculation with truncation of the form:
+ *
+ * ((int)(coefficient * 100000) * 32768)/100000
+ *
+ * This is done to the red and green coefficients (the ones
+ * provided to the API) then blue is calculated from them so the
+ * result adds up to 32768. In the worst case this can result in
+ * a -1 error in red and green and a +2 error in blue. Consequently
+ * the worst case in the calculation below is 2/32768 error.
+ *
+ * TODO: consider fixing this in libpng by rounding the calculation
+ * limiting the error to 1/32768.
+ *
+ * Handling this by adding 2/32768 here avoids needing to increase
+ * the global error limits to take this into account.)
+ */
+ gray = r * data.red_coefficient + g * data.green_coefficient +
+ b * data.blue_coefficient;
+ err = re * data.red_coefficient + ge * data.green_coefficient +
+ be * data.blue_coefficient + 2./32768 + gray * 5 * DBL_EPSILON;
+ }
+
+ else
+ {
+ /* The calculation happens in linear space, and this produces much
+ * wider errors in the encoded space. These are handled here by
+ * factoring the errors in to the calculation. There are two table
+ * lookups in the calculation and each introduces a quantization
+ * error defined by the table size.
+ */
+ const png_modifier *pm = display->pm;
+ double in_qe = (that->sample_depth > 8 ? .5/65535 : .5/255);
+ double out_qe = (that->sample_depth > 8 ? .5/65535 :
+ (pm->assume_16_bit_calculations ? .5/(1<<display->max_gamma_8) :
+ .5/255));
+ double rhi, ghi, bhi, grayhi;
+ double g1 = 1/data.gamma;
+
+ rhi = r + re + in_qe; if (rhi > 1) rhi = 1;
+ r -= re + in_qe; if (r < 0) r = 0;
+ ghi = g + ge + in_qe; if (ghi > 1) ghi = 1;
+ g -= ge + in_qe; if (g < 0) g = 0;
+ bhi = b + be + in_qe; if (bhi > 1) bhi = 1;
+ b -= be + in_qe; if (b < 0) b = 0;
+
+ r = pow(r, g1)*(1-DBL_EPSILON); rhi = pow(rhi, g1)*(1+DBL_EPSILON);
+ g = pow(g, g1)*(1-DBL_EPSILON); ghi = pow(ghi, g1)*(1+DBL_EPSILON);
+ b = pow(b, g1)*(1-DBL_EPSILON); bhi = pow(bhi, g1)*(1+DBL_EPSILON);
+
+ /* Work out the lower and upper bounds for the gray value in the
+ * encoded space, then work out an average and error. Remove the
+ * previously added input quantization error at this point.
+ */
+ gray = r * data.red_coefficient + g * data.green_coefficient +
+ b * data.blue_coefficient - 2./32768 - out_qe;
+ if (gray <= 0)
+ gray = 0;
+ else
+ {
+ gray *= (1 - 6 * DBL_EPSILON);
+ gray = pow(gray, data.gamma) * (1-DBL_EPSILON);
+ }
+
+ grayhi = rhi * data.red_coefficient + ghi * data.green_coefficient +
+ bhi * data.blue_coefficient + 2./32768 + out_qe;
+ grayhi *= (1 + 6 * DBL_EPSILON);
+ if (grayhi >= 1)
+ grayhi = 1;
+ else
+ grayhi = pow(grayhi, data.gamma) * (1+DBL_EPSILON);
+
+ err = (grayhi - gray) / 2;
+ gray = (grayhi + gray) / 2;
+
+ if (err <= in_qe)
+ err = gray * DBL_EPSILON;
+
+ else
+ err -= in_qe;
+
+ /* Validate that the error is within limits (this has caused
+ * problems before, it's much easier to detect them here.)
+ */
+ if (err > pm->limit)
+ {
+ size_t pos = 0;
+ char buffer[128];
+
+ pos = safecat(buffer, sizeof buffer, pos, "rgb_to_gray error ");
+ pos = safecatd(buffer, sizeof buffer, pos, err, 6);
+ pos = safecat(buffer, sizeof buffer, pos, " exceeds limit ");
+ pos = safecatd(buffer, sizeof buffer, pos, pm->limit, 6);
+ png_error(pp, buffer);
+ }
+ }
+ }
+# endif /* !DIGITIZE */
+
+ that->bluef = that->greenf = that->redf = gray;
+ that->bluee = that->greene = that->rede = err;
+
+ /* The sBIT is the minium of the three colour channel sBITs. */
+ if (that->red_sBIT > that->green_sBIT)
+ that->red_sBIT = that->green_sBIT;
+ if (that->red_sBIT > that->blue_sBIT)
+ that->red_sBIT = that->blue_sBIT;
+ that->blue_sBIT = that->green_sBIT = that->red_sBIT;
+
+ /* And remove the colour bit in the type: */
+ if (that->colour_type == PNG_COLOR_TYPE_RGB)
+ that->colour_type = PNG_COLOR_TYPE_GRAY;
+ else if (that->colour_type == PNG_COLOR_TYPE_RGB_ALPHA)
+ that->colour_type = PNG_COLOR_TYPE_GRAY_ALPHA;
+ }
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_rgb_to_gray_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ UNUSED(bit_depth)
+
+ this->next = *that;
+ *that = this;
+
+ return (colour_type & PNG_COLOR_MASK_COLOR) != 0;
+}
+
+#undef data
+IT(rgb_to_gray);
+#undef PT
+#define PT ITSTRUCT(rgb_to_gray)
+#undef image_transform_ini
+#define image_transform_ini image_transform_default_ini
+#endif /* PNG_READ_RGB_TO_GRAY_SUPPORTED */
+
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
+/* png_set_background(png_structp, png_const_color_16p background_color,
+ * int background_gamma_code, int need_expand, double background_gamma)
+ * png_set_background_fixed(png_structp, png_const_color_16p background_color,
+ * int background_gamma_code, int need_expand,
+ * png_fixed_point background_gamma)
+ *
+ * This ignores the gamma (at present.)
+*/
+#define data ITDATA(background)
+static image_pixel data;
+
+static void
+image_transform_png_set_background_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ png_byte colour_type, bit_depth;
+ png_byte random_bytes[8]; /* 8 bytes - 64 bits - the biggest pixel */
+ int expand;
+ png_color_16 back;
+
+ /* We need a background colour, because we don't know exactly what transforms
+ * have been set we have to supply the colour in the original file format and
+ * so we need to know what that is! The background colour is stored in the
+ * transform_display.
+ */
+ RANDOMIZE(random_bytes);
+
+ /* Read the random value, for colour type 3 the background colour is actually
+ * expressed as a 24bit rgb, not an index.
+ */
+ colour_type = that->this.colour_type;
+ if (colour_type == 3)
+ {
+ colour_type = PNG_COLOR_TYPE_RGB;
+ bit_depth = 8;
+ expand = 0; /* passing in an RGB not a pixel index */
+ }
+
+ else
+ {
+ if (that->this.has_tRNS)
+ that->this.is_transparent = 1;
+
+ bit_depth = that->this.bit_depth;
+ expand = 1;
+ }
+
+ image_pixel_init(&data, random_bytes, colour_type,
+ bit_depth, 0/*x*/, 0/*unused: palette*/, NULL/*format*/);
+
+ /* Extract the background colour from this image_pixel, but make sure the
+ * unused fields of 'back' are garbage.
+ */
+ RANDOMIZE(back);
+
+ if (colour_type & PNG_COLOR_MASK_COLOR)
+ {
+ back.red = (png_uint_16)data.red;
+ back.green = (png_uint_16)data.green;
+ back.blue = (png_uint_16)data.blue;
+ }
+
+ else
+ back.gray = (png_uint_16)data.red;
+
+# ifdef PNG_FLOATING_POINT_SUPPORTED
+ png_set_background(pp, &back, PNG_BACKGROUND_GAMMA_FILE, expand, 0);
+# else
+ png_set_background_fixed(pp, &back, PNG_BACKGROUND_GAMMA_FILE, expand, 0);
+# endif
+
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_background_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ /* Check for tRNS first: */
+ if (that->have_tRNS && that->colour_type != PNG_COLOR_TYPE_PALETTE)
+ image_pixel_add_alpha(that, &display->this, 1/*for background*/);
+
+ /* This is only necessary if the alpha value is less than 1. */
+ if (that->alphaf < 1)
+ {
+ /* Now we do the background calculation without any gamma correction. */
+ if (that->alphaf <= 0)
+ {
+ that->redf = data.redf;
+ that->greenf = data.greenf;
+ that->bluef = data.bluef;
+
+ that->rede = data.rede;
+ that->greene = data.greene;
+ that->bluee = data.bluee;
+
+ that->red_sBIT= data.red_sBIT;
+ that->green_sBIT= data.green_sBIT;
+ that->blue_sBIT= data.blue_sBIT;
+ }
+
+ else /* 0 < alpha < 1 */
+ {
+ double alf = 1 - that->alphaf;
+
+ that->redf = that->redf * that->alphaf + data.redf * alf;
+ that->rede = that->rede * that->alphaf + data.rede * alf +
+ DBL_EPSILON;
+ that->greenf = that->greenf * that->alphaf + data.greenf * alf;
+ that->greene = that->greene * that->alphaf + data.greene * alf +
+ DBL_EPSILON;
+ that->bluef = that->bluef * that->alphaf + data.bluef * alf;
+ that->bluee = that->bluee * that->alphaf + data.bluee * alf +
+ DBL_EPSILON;
+ }
+
+ /* Remove the alpha type and set the alpha (not in that order.) */
+ that->alphaf = 1;
+ that->alphae = 0;
+ }
+
+ if (that->colour_type == PNG_COLOR_TYPE_RGB_ALPHA)
+ that->colour_type = PNG_COLOR_TYPE_RGB;
+ else if (that->colour_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+ that->colour_type = PNG_COLOR_TYPE_GRAY;
+ /* PNG_COLOR_TYPE_PALETTE is not changed */
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+#define image_transform_png_set_background_add image_transform_default_add
+
+#undef data
+IT(background);
+#undef PT
+#define PT ITSTRUCT(background)
+#endif /* PNG_READ_BACKGROUND_SUPPORTED */
+
+/* png_set_quantize(png_structp, png_colorp palette, int num_palette,
+ * int maximum_colors, png_const_uint_16p histogram, int full_quantize)
+ *
+ * Very difficult to validate this!
+ */
+/*NOTE: TBD NYI */
+
+/* The data layout transforms are handled by swapping our own channel data,
+ * necessarily these need to happen at the end of the transform list because the
+ * semantic of the channels changes after these are executed. Some of these,
+ * like set_shift and set_packing, can't be done at present because they change
+ * the layout of the data at the sub-sample level so sample() won't get the
+ * right answer.
+ */
+/* png_set_invert_alpha */
+#ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
+/* Invert the alpha channel
+ *
+ * png_set_invert_alpha(png_structrp png_ptr)
+ */
+static void
+image_transform_png_set_invert_alpha_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ png_set_invert_alpha(pp);
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_invert_alpha_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ if (that->colour_type & 4)
+ that->alpha_inverted = 1;
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_invert_alpha_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ UNUSED(bit_depth)
+
+ this->next = *that;
+ *that = this;
+
+ /* Only has an effect on pixels with alpha: */
+ return (colour_type & 4) != 0;
+}
+
+IT(invert_alpha);
+#undef PT
+#define PT ITSTRUCT(invert_alpha)
+
+#endif /* PNG_READ_INVERT_ALPHA_SUPPORTED */
+
+/* png_set_bgr */
+#ifdef PNG_READ_BGR_SUPPORTED
+/* Swap R,G,B channels to order B,G,R.
+ *
+ * png_set_bgr(png_structrp png_ptr)
+ *
+ * This only has an effect on RGB and RGBA pixels.
+ */
+static void
+image_transform_png_set_bgr_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ png_set_bgr(pp);
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_bgr_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ if (that->colour_type == PNG_COLOR_TYPE_RGB ||
+ that->colour_type == PNG_COLOR_TYPE_RGBA)
+ that->swap_rgb = 1;
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_bgr_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ UNUSED(bit_depth)
+
+ this->next = *that;
+ *that = this;
+
+ return colour_type == PNG_COLOR_TYPE_RGB ||
+ colour_type == PNG_COLOR_TYPE_RGBA;
+}
+
+IT(bgr);
+#undef PT
+#define PT ITSTRUCT(bgr)
+
+#endif /* PNG_READ_BGR_SUPPORTED */
+
+/* png_set_swap_alpha */
+#ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
+/* Put the alpha channel first.
+ *
+ * png_set_swap_alpha(png_structrp png_ptr)
+ *
+ * This only has an effect on GA and RGBA pixels.
+ */
+static void
+image_transform_png_set_swap_alpha_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ png_set_swap_alpha(pp);
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_swap_alpha_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ if (that->colour_type == PNG_COLOR_TYPE_GA ||
+ that->colour_type == PNG_COLOR_TYPE_RGBA)
+ that->alpha_first = 1;
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_swap_alpha_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ UNUSED(bit_depth)
+
+ this->next = *that;
+ *that = this;
+
+ return colour_type == PNG_COLOR_TYPE_GA ||
+ colour_type == PNG_COLOR_TYPE_RGBA;
+}
+
+IT(swap_alpha);
+#undef PT
+#define PT ITSTRUCT(swap_alpha)
+
+#endif /* PNG_READ_SWAP_ALPHA_SUPPORTED */
+
+/* png_set_swap */
+#ifdef PNG_READ_SWAP_SUPPORTED
+/* Byte swap 16-bit components.
+ *
+ * png_set_swap(png_structrp png_ptr)
+ */
+static void
+image_transform_png_set_swap_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ png_set_swap(pp);
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_swap_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ if (that->bit_depth == 16)
+ that->swap16 = 1;
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_swap_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ UNUSED(colour_type)
+
+ this->next = *that;
+ *that = this;
+
+ return bit_depth == 16;
+}
+
+IT(swap);
+#undef PT
+#define PT ITSTRUCT(swap)
+
+#endif /* PNG_READ_SWAP_SUPPORTED */
+
+#ifdef PNG_READ_FILLER_SUPPORTED
+/* Add a filler byte to 8-bit Gray or 24-bit RGB images.
+ *
+ * png_set_filler, (png_structp png_ptr, png_uint_32 filler, int flags));
+ *
+ * Flags:
+ *
+ * PNG_FILLER_BEFORE
+ * PNG_FILLER_AFTER
+ */
+#define data ITDATA(filler)
+static struct
+{
+ png_uint_32 filler;
+ int flags;
+} data;
+
+static void
+image_transform_png_set_filler_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ /* Need a random choice for 'before' and 'after' as well as for the
+ * filler. The 'filler' value has all 32 bits set, but only bit_depth
+ * will be used. At this point we don't know bit_depth.
+ */
+ RANDOMIZE(data.filler);
+ data.flags = random_choice();
+
+ png_set_filler(pp, data.filler, data.flags);
+
+ /* The standard display handling stuff also needs to know that
+ * there is a filler, so set that here.
+ */
+ that->this.filler = 1;
+
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_filler_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ if (that->bit_depth >= 8 &&
+ (that->colour_type == PNG_COLOR_TYPE_RGB ||
+ that->colour_type == PNG_COLOR_TYPE_GRAY))
+ {
+ const unsigned int max = (1U << that->bit_depth)-1;
+ that->alpha = data.filler & max;
+ that->alphaf = ((double)that->alpha) / max;
+ that->alphae = 0;
+
+ /* The filler has been stored in the alpha channel, we must record
+ * that this has been done for the checking later on, the color
+ * type is faked to have an alpha channel, but libpng won't report
+ * this; the app has to know the extra channel is there and this
+ * was recording in standard_display::filler above.
+ */
+ that->colour_type |= 4; /* alpha added */
+ that->alpha_first = data.flags == PNG_FILLER_BEFORE;
+ }
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_filler_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ this->next = *that;
+ *that = this;
+
+ return bit_depth >= 8 && (colour_type == PNG_COLOR_TYPE_RGB ||
+ colour_type == PNG_COLOR_TYPE_GRAY);
+}
+
+#undef data
+IT(filler);
+#undef PT
+#define PT ITSTRUCT(filler)
+
+/* png_set_add_alpha, (png_structp png_ptr, png_uint_32 filler, int flags)); */
+/* Add an alpha byte to 8-bit Gray or 24-bit RGB images. */
+#define data ITDATA(add_alpha)
+static struct
+{
+ png_uint_32 filler;
+ int flags;
+} data;
+
+static void
+image_transform_png_set_add_alpha_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ /* Need a random choice for 'before' and 'after' as well as for the
+ * filler. The 'filler' value has all 32 bits set, but only bit_depth
+ * will be used. At this point we don't know bit_depth.
+ */
+ RANDOMIZE(data.filler);
+ data.flags = random_choice();
+
+ png_set_add_alpha(pp, data.filler, data.flags);
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_add_alpha_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ if (that->bit_depth >= 8 &&
+ (that->colour_type == PNG_COLOR_TYPE_RGB ||
+ that->colour_type == PNG_COLOR_TYPE_GRAY))
+ {
+ const unsigned int max = (1U << that->bit_depth)-1;
+ that->alpha = data.filler & max;
+ that->alphaf = ((double)that->alpha) / max;
+ that->alphae = 0;
+
+ that->colour_type |= 4; /* alpha added */
+ that->alpha_first = data.flags == PNG_FILLER_BEFORE;
+ }
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_add_alpha_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ this->next = *that;
+ *that = this;
+
+ return bit_depth >= 8 && (colour_type == PNG_COLOR_TYPE_RGB ||
+ colour_type == PNG_COLOR_TYPE_GRAY);
+}
+
+#undef data
+IT(add_alpha);
+#undef PT
+#define PT ITSTRUCT(add_alpha)
+
+#endif /* PNG_READ_FILLER_SUPPORTED */
+
+/* png_set_packing */
+#ifdef PNG_READ_PACK_SUPPORTED
+/* Use 1 byte per pixel in 1, 2, or 4-bit depth files.
+ *
+ * png_set_packing(png_structrp png_ptr)
+ *
+ * This should only affect grayscale and palette images with less than 8 bits
+ * per pixel.
+ */
+static void
+image_transform_png_set_packing_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ png_set_packing(pp);
+ that->unpacked = 1;
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_packing_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ /* The general expand case depends on what the colour type is,
+ * low bit-depth pixel values are unpacked into bytes without
+ * scaling, so sample_depth is not changed.
+ */
+ if (that->bit_depth < 8) /* grayscale or palette */
+ that->bit_depth = 8;
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_packing_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ UNUSED(colour_type)
+
+ this->next = *that;
+ *that = this;
+
+ /* Nothing should happen unless the bit depth is less than 8: */
+ return bit_depth < 8;
+}
+
+IT(packing);
+#undef PT
+#define PT ITSTRUCT(packing)
+
+#endif /* PNG_READ_PACK_SUPPORTED */
+
+/* png_set_packswap */
+#ifdef PNG_READ_PACKSWAP_SUPPORTED
+/* Swap pixels packed into bytes; reverses the order on screen so that
+ * the high order bits correspond to the rightmost pixels.
+ *
+ * png_set_packswap(png_structrp png_ptr)
+ */
+static void
+image_transform_png_set_packswap_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ png_set_packswap(pp);
+ that->this.littleendian = 1;
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_packswap_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ if (that->bit_depth < 8)
+ that->littleendian = 1;
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_packswap_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ UNUSED(colour_type)
+
+ this->next = *that;
+ *that = this;
+
+ return bit_depth < 8;
+}
+
+IT(packswap);
+#undef PT
+#define PT ITSTRUCT(packswap)
+
+#endif /* PNG_READ_PACKSWAP_SUPPORTED */
+
+
+/* png_set_invert_mono */
+#ifdef PNG_READ_INVERT_MONO_SUPPORTED
+/* Invert the gray channel
+ *
+ * png_set_invert_mono(png_structrp png_ptr)
+ */
+static void
+image_transform_png_set_invert_mono_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ png_set_invert_mono(pp);
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_invert_mono_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ if (that->colour_type & 4)
+ that->mono_inverted = 1;
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_invert_mono_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ UNUSED(bit_depth)
+
+ this->next = *that;
+ *that = this;
+
+ /* Only has an effect on pixels with no colour: */
+ return (colour_type & 2) == 0;
+}
+
+IT(invert_mono);
+#undef PT
+#define PT ITSTRUCT(invert_mono)
+
+#endif /* PNG_READ_INVERT_MONO_SUPPORTED */
+
+#ifdef PNG_READ_SHIFT_SUPPORTED
+/* png_set_shift(png_structp, png_const_color_8p true_bits)
+ *
+ * The output pixels will be shifted by the given true_bits
+ * values.
+ */
+#define data ITDATA(shift)
+static png_color_8 data;
+
+static void
+image_transform_png_set_shift_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ /* Get a random set of shifts. The shifts need to do something
+ * to test the transform, so they are limited to the bit depth
+ * of the input image. Notice that in the following the 'gray'
+ * field is randomized independently. This acts as a check that
+ * libpng does use the correct field.
+ */
+ const unsigned int depth = that->this.bit_depth;
+
+ data.red = (png_byte)/*SAFE*/(random_mod(depth)+1);
+ data.green = (png_byte)/*SAFE*/(random_mod(depth)+1);
+ data.blue = (png_byte)/*SAFE*/(random_mod(depth)+1);
+ data.gray = (png_byte)/*SAFE*/(random_mod(depth)+1);
+ data.alpha = (png_byte)/*SAFE*/(random_mod(depth)+1);
+
+ png_set_shift(pp, &data);
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_shift_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ /* Copy the correct values into the sBIT fields, libpng does not do
+ * anything to palette data:
+ */
+ if (that->colour_type != PNG_COLOR_TYPE_PALETTE)
+ {
+ that->sig_bits = 1;
+
+ /* The sBIT fields are reset to the values previously sent to
+ * png_set_shift according to the colour type.
+ * does.
+ */
+ if (that->colour_type & 2) /* RGB channels */
+ {
+ that->red_sBIT = data.red;
+ that->green_sBIT = data.green;
+ that->blue_sBIT = data.blue;
+ }
+
+ else /* One grey channel */
+ that->red_sBIT = that->green_sBIT = that->blue_sBIT = data.gray;
+
+ that->alpha_sBIT = data.alpha;
+ }
+
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_shift_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ UNUSED(bit_depth)
+
+ this->next = *that;
+ *that = this;
+
+ return colour_type != PNG_COLOR_TYPE_PALETTE;
+}
+
+IT(shift);
+#undef PT
+#define PT ITSTRUCT(shift)
+
+#endif /* PNG_READ_SHIFT_SUPPORTED */
+
+#ifdef THIS_IS_THE_PROFORMA
+static void
+image_transform_png_set_@_set(const image_transform *this,
+ transform_display *that, png_structp pp, png_infop pi)
+{
+ png_set_@(pp);
+ this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_@_mod(const image_transform *this,
+ image_pixel *that, png_const_structp pp,
+ const transform_display *display)
+{
+ this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_@_add(image_transform *this,
+ const image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+ this->next = *that;
+ *that = this;
+
+ return 1;
+}
+
+IT(@);
+#endif
+
+
+/* This may just be 'end' if all the transforms are disabled! */
+static image_transform *const image_transform_first = &PT;
+
+static void
+transform_enable(const char *name)
+{
+ /* Everything starts out enabled, so if we see an 'enable' disabled
+ * everything else the first time round.
+ */
+ static int all_disabled = 0;
+ int found_it = 0;
+ image_transform *list = image_transform_first;
+
+ while (list != &image_transform_end)
+ {
+ if (strcmp(list->name, name) == 0)
+ {
+ list->enable = 1;
+ found_it = 1;
+ }
+ else if (!all_disabled)
+ list->enable = 0;
+
+ list = list->list;
+ }
+
+ all_disabled = 1;
+
+ if (!found_it)
+ {
+ fprintf(stderr, "pngvalid: --transform-enable=%s: unknown transform\n",
+ name);
+ exit(99);
+ }
+}
+
+static void
+transform_disable(const char *name)
+{
+ image_transform *list = image_transform_first;
+
+ while (list != &image_transform_end)
+ {
+ if (strcmp(list->name, name) == 0)
+ {
+ list->enable = 0;
+ return;
+ }
+
+ list = list->list;
+ }
+
+ fprintf(stderr, "pngvalid: --transform-disable=%s: unknown transform\n",
+ name);
+ exit(99);
+}
+
+static void
+image_transform_reset_count(void)
+{
+ image_transform *next = image_transform_first;
+ int count = 0;
+
+ while (next != &image_transform_end)
+ {
+ next->local_use = 0;
+ next->next = 0;
+ next = next->list;
+ ++count;
+ }
+
+ /* This can only happen if we every have more than 32 transforms (excluding
+ * the end) in the list.
+ */
+ if (count > 32) abort();
+}
+
+static int
+image_transform_test_counter(png_uint_32 counter, unsigned int max)
+{
+ /* Test the list to see if there is any point contining, given a current
+ * counter and a 'max' value.
+ */
+ image_transform *next = image_transform_first;
+
+ while (next != &image_transform_end)
+ {
+ /* For max 0 or 1 continue until the counter overflows: */
+ counter >>= 1;
+
+ /* Continue if any entry hasn't reacked the max. */
+ if (max > 1 && next->local_use < max)
+ return 1;
+ next = next->list;
+ }
+
+ return max <= 1 && counter == 0;
+}
+
+static png_uint_32
+image_transform_add(const image_transform **this, unsigned int max,
+ png_uint_32 counter, char *name, size_t sizeof_name, size_t *pos,
+ png_byte colour_type, png_byte bit_depth)
+{
+ for (;;) /* until we manage to add something */
+ {
+ png_uint_32 mask;
+ image_transform *list;
+
+ /* Find the next counter value, if the counter is zero this is the start
+ * of the list. This routine always returns the current counter (not the
+ * next) so it returns 0 at the end and expects 0 at the beginning.
+ */
+ if (counter == 0) /* first time */
+ {
+ image_transform_reset_count();
+ if (max <= 1)
+ counter = 1;
+ else
+ counter = random_32();
+ }
+ else /* advance the counter */
+ {
+ switch (max)
+ {
+ case 0: ++counter; break;
+ case 1: counter <<= 1; break;
+ default: counter = random_32(); break;
+ }
+ }
+
+ /* Now add all these items, if possible */
+ *this = &image_transform_end;
+ list = image_transform_first;
+ mask = 1;
+
+ /* Go through the whole list adding anything that the counter selects: */
+ while (list != &image_transform_end)
+ {
+ if ((counter & mask) != 0 && list->enable &&
+ (max == 0 || list->local_use < max))
+ {
+ /* Candidate to add: */
+ if (list->add(list, this, colour_type, bit_depth) || max == 0)
+ {
+ /* Added, so add to the name too. */
+ *pos = safecat(name, sizeof_name, *pos, " +");
+ *pos = safecat(name, sizeof_name, *pos, list->name);
+ }
+
+ else
+ {
+ /* Not useful and max>0, so remove it from *this: */
+ *this = list->next;
+ list->next = 0;
+
+ /* And, since we know it isn't useful, stop it being added again
+ * in this run:
+ */
+ list->local_use = max;
+ }
+ }
+
+ mask <<= 1;
+ list = list->list;
+ }
+
+ /* Now if anything was added we have something to do. */
+ if (*this != &image_transform_end)
+ return counter;
+
+ /* Nothing added, but was there anything in there to add? */
+ if (!image_transform_test_counter(counter, max))
+ return 0;
+ }
+}
+
+static void
+perform_transform_test(png_modifier *pm)
+{
+ png_byte colour_type = 0;
+ png_byte bit_depth = 0;
+ unsigned int palette_number = 0;
+
+ while (next_format(&colour_type, &bit_depth, &palette_number, pm->test_lbg,
+ pm->test_tRNS))
+ {
+ png_uint_32 counter = 0;
+ size_t base_pos;
+ char name[64];
+
+ base_pos = safecat(name, sizeof name, 0, "transform:");
+
+ for (;;)
+ {
+ size_t pos = base_pos;
+ const image_transform *list = 0;
+
+ /* 'max' is currently hardwired to '1'; this should be settable on the
+ * command line.
+ */
+ counter = image_transform_add(&list, 1/*max*/, counter,
+ name, sizeof name, &pos, colour_type, bit_depth);
+
+ if (counter == 0)
+ break;
+
+ /* The command line can change this to checking interlaced images. */
+ do
+ {
+ pm->repeat = 0;
+ transform_test(pm, FILEID(colour_type, bit_depth, palette_number,
+ pm->interlace_type, 0, 0, 0), list, name);
+
+ if (fail(pm))
+ return;
+ }
+ while (pm->repeat);
+ }
+ }
+}
+#endif /* PNG_READ_TRANSFORMS_SUPPORTED */
+
+/********************************* GAMMA TESTS ********************************/
+#ifdef PNG_READ_GAMMA_SUPPORTED
+/* Reader callbacks and implementations, where they differ from the standard
+ * ones.
+ */
+typedef struct gamma_display
+{
+ standard_display this;
+
+ /* Parameters */
+ png_modifier* pm;
+ double file_gamma;
+ double screen_gamma;
+ double background_gamma;
+ png_byte sbit;
+ int threshold_test;
+ int use_input_precision;
+ int scale16;
+ int expand16;
+ int do_background;
+ png_color_16 background_color;
+
+ /* Local variables */
+ double maxerrout;
+ double maxerrpc;
+ double maxerrabs;
+} gamma_display;
+
+#define ALPHA_MODE_OFFSET 4
+
+static void
+gamma_display_init(gamma_display *dp, png_modifier *pm, png_uint_32 id,
+ double file_gamma, double screen_gamma, png_byte sbit, int threshold_test,
+ int use_input_precision, int scale16, int expand16,
+ int do_background, const png_color_16 *pointer_to_the_background_color,
+ double background_gamma)
+{
+ /* Standard fields */
+ standard_display_init(&dp->this, &pm->this, id, do_read_interlace,
+ pm->use_update_info);
+
+ /* Parameter fields */
+ dp->pm = pm;
+ dp->file_gamma = file_gamma;
+ dp->screen_gamma = screen_gamma;
+ dp->background_gamma = background_gamma;
+ dp->sbit = sbit;
+ dp->threshold_test = threshold_test;
+ dp->use_input_precision = use_input_precision;
+ dp->scale16 = scale16;
+ dp->expand16 = expand16;
+ dp->do_background = do_background;
+ if (do_background && pointer_to_the_background_color != 0)
+ dp->background_color = *pointer_to_the_background_color;
+ else
+ memset(&dp->background_color, 0, sizeof dp->background_color);
+
+ /* Local variable fields */
+ dp->maxerrout = dp->maxerrpc = dp->maxerrabs = 0;
+}
+
+static void
+gamma_info_imp(gamma_display *dp, png_structp pp, png_infop pi)
+{
+ /* Reuse the standard stuff as appropriate. */
+ standard_info_part1(&dp->this, pp, pi);
+
+ /* If requested strip 16 to 8 bits - this is handled automagically below
+ * because the output bit depth is read from the library. Note that there
+ * are interactions with sBIT but, internally, libpng makes sbit at most
+ * PNG_MAX_GAMMA_8 prior to 1.7 when doing the following.
+ */
+ if (dp->scale16)
+# ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
+ png_set_scale_16(pp);
+# else
+ /* The following works both in 1.5.4 and earlier versions: */
+# ifdef PNG_READ_16_TO_8_SUPPORTED
+ png_set_strip_16(pp);
+# else
+ png_error(pp, "scale16 (16 to 8 bit conversion) not supported");
+# endif
+# endif
+
+ if (dp->expand16)
+# ifdef PNG_READ_EXPAND_16_SUPPORTED
+ png_set_expand_16(pp);
+# else
+ png_error(pp, "expand16 (8 to 16 bit conversion) not supported");
+# endif
+
+ if (dp->do_background >= ALPHA_MODE_OFFSET)
+ {
+# ifdef PNG_READ_ALPHA_MODE_SUPPORTED
+ {
+ /* This tests the alpha mode handling, if supported. */
+ int mode = dp->do_background - ALPHA_MODE_OFFSET;
+
+ /* The gamma value is the output gamma, and is in the standard,
+ * non-inverted, represenation. It provides a default for the PNG file
+ * gamma, but since the file has a gAMA chunk this does not matter.
+ */
+ const double sg = dp->screen_gamma;
+# ifndef PNG_FLOATING_POINT_SUPPORTED
+ const png_fixed_point g = fix(sg);
+# endif
+
+# ifdef PNG_FLOATING_POINT_SUPPORTED
+ png_set_alpha_mode(pp, mode, sg);
+# else
+ png_set_alpha_mode_fixed(pp, mode, g);
+# endif
+
+ /* However, for the standard Porter-Duff algorithm the output defaults
+ * to be linear, so if the test requires non-linear output it must be
+ * corrected here.
+ */
+ if (mode == PNG_ALPHA_STANDARD && sg != 1)
+ {
+# ifdef PNG_FLOATING_POINT_SUPPORTED
+ png_set_gamma(pp, sg, dp->file_gamma);
+# else
+ png_fixed_point f = fix(dp->file_gamma);
+ png_set_gamma_fixed(pp, g, f);
+# endif
+ }
+ }
+# else
+ png_error(pp, "alpha mode handling not supported");
+# endif
+ }
+
+ else
+ {
+ /* Set up gamma processing. */
+# ifdef PNG_FLOATING_POINT_SUPPORTED
+ png_set_gamma(pp, dp->screen_gamma, dp->file_gamma);
+# else
+ {
+ png_fixed_point s = fix(dp->screen_gamma);
+ png_fixed_point f = fix(dp->file_gamma);
+ png_set_gamma_fixed(pp, s, f);
+ }
+# endif
+
+ if (dp->do_background)
+ {
+# ifdef PNG_READ_BACKGROUND_SUPPORTED
+ /* NOTE: this assumes the caller provided the correct background gamma!
+ */
+ const double bg = dp->background_gamma;
+# ifndef PNG_FLOATING_POINT_SUPPORTED
+ const png_fixed_point g = fix(bg);
+# endif
+
+# ifdef PNG_FLOATING_POINT_SUPPORTED
+ png_set_background(pp, &dp->background_color, dp->do_background,
+ 0/*need_expand*/, bg);
+# else
+ png_set_background_fixed(pp, &dp->background_color,
+ dp->do_background, 0/*need_expand*/, g);
+# endif
+# else
+ png_error(pp, "png_set_background not supported");
+# endif
+ }
+ }
+
+ {
+ int i = dp->this.use_update_info;
+ /* Always do one call, even if use_update_info is 0. */
+ do
+ png_read_update_info(pp, pi);
+ while (--i > 0);
+ }
+
+ /* Now we may get a different cbRow: */
+ standard_info_part2(&dp->this, pp, pi, 1 /*images*/);
+}
+
+static void PNGCBAPI
+gamma_info(png_structp pp, png_infop pi)
+{
+ gamma_info_imp(voidcast(gamma_display*, png_get_progressive_ptr(pp)), pp,
+ pi);
+}
+
+/* Validate a single component value - the routine gets the input and output
+ * sample values as unscaled PNG component values along with a cache of all the
+ * information required to validate the values.
+ */
+typedef struct validate_info
+{
+ png_const_structp pp;
+ gamma_display *dp;
+ png_byte sbit;
+ int use_input_precision;
+ int do_background;
+ int scale16;
+ unsigned int sbit_max;
+ unsigned int isbit_shift;
+ unsigned int outmax;
+
+ double gamma_correction; /* Overall correction required. */
+ double file_inverse; /* Inverse of file gamma. */
+ double screen_gamma;
+ double screen_inverse; /* Inverse of screen gamma. */
+
+ double background_red; /* Linear background value, red or gray. */
+ double background_green;
+ double background_blue;
+
+ double maxabs;
+ double maxpc;
+ double maxcalc;
+ double maxout;
+ double maxout_total; /* Total including quantization error */
+ double outlog;
+ int outquant;
+}
+validate_info;
+
+static void
+init_validate_info(validate_info *vi, gamma_display *dp, png_const_structp pp,
+ int in_depth, int out_depth)
+{
+ const unsigned int outmax = (1U<<out_depth)-1;
+
+ vi->pp = pp;
+ vi->dp = dp;
+
+ if (dp->sbit > 0 && dp->sbit < in_depth)
+ {
+ vi->sbit = dp->sbit;
+ vi->isbit_shift = in_depth - dp->sbit;
+ }
+
+ else
+ {
+ vi->sbit = (png_byte)in_depth;
+ vi->isbit_shift = 0;
+ }
+
+ vi->sbit_max = (1U << vi->sbit)-1;
+
+ /* This mimics the libpng threshold test, '0' is used to prevent gamma
+ * correction in the validation test.
+ */
+ vi->screen_gamma = dp->screen_gamma;
+ if (fabs(vi->screen_gamma-1) < PNG_GAMMA_THRESHOLD)
+ vi->screen_gamma = vi->screen_inverse = 0;
+ else
+ vi->screen_inverse = 1/vi->screen_gamma;
+
+ vi->use_input_precision = dp->use_input_precision;
+ vi->outmax = outmax;
+ vi->maxabs = abserr(dp->pm, in_depth, out_depth);
+ vi->maxpc = pcerr(dp->pm, in_depth, out_depth);
+ vi->maxcalc = calcerr(dp->pm, in_depth, out_depth);
+ vi->maxout = outerr(dp->pm, in_depth, out_depth);
+ vi->outquant = output_quantization_factor(dp->pm, in_depth, out_depth);
+ vi->maxout_total = vi->maxout + vi->outquant * .5;
+ vi->outlog = outlog(dp->pm, in_depth, out_depth);
+
+ if ((dp->this.colour_type & PNG_COLOR_MASK_ALPHA) != 0 ||
+ (dp->this.colour_type == 3 && dp->this.is_transparent) ||
+ ((dp->this.colour_type == 0 || dp->this.colour_type == 2) &&
+ dp->this.has_tRNS))
+ {
+ vi->do_background = dp->do_background;
+
+ if (vi->do_background != 0)
+ {
+ const double bg_inverse = 1/dp->background_gamma;
+ double r, g, b;
+
+ /* Caller must at least put the gray value into the red channel */
+ r = dp->background_color.red; r /= outmax;
+ g = dp->background_color.green; g /= outmax;
+ b = dp->background_color.blue; b /= outmax;
+
+# if 0
+ /* libpng doesn't do this optimization, if we do pngvalid will fail.
+ */
+ if (fabs(bg_inverse-1) >= PNG_GAMMA_THRESHOLD)
+# endif
+ {
+ r = pow(r, bg_inverse);
+ g = pow(g, bg_inverse);
+ b = pow(b, bg_inverse);
+ }
+
+ vi->background_red = r;
+ vi->background_green = g;
+ vi->background_blue = b;
+ }
+ }
+ else /* Do not expect any background processing */
+ vi->do_background = 0;
+
+ if (vi->do_background == 0)
+ vi->background_red = vi->background_green = vi->background_blue = 0;
+
+ vi->gamma_correction = 1/(dp->file_gamma*dp->screen_gamma);
+ if (fabs(vi->gamma_correction-1) < PNG_GAMMA_THRESHOLD)
+ vi->gamma_correction = 0;
+
+ vi->file_inverse = 1/dp->file_gamma;
+ if (fabs(vi->file_inverse-1) < PNG_GAMMA_THRESHOLD)
+ vi->file_inverse = 0;
+
+ vi->scale16 = dp->scale16;
+}
+
+/* This function handles composition of a single non-alpha component. The
+ * argument is the input sample value, in the range 0..1, and the alpha value.
+ * The result is the composed, linear, input sample. If alpha is less than zero
+ * this is the alpha component and the function should not be called!
+ */
+static double
+gamma_component_compose(int do_background, double input_sample, double alpha,
+ double background, int *compose)
+{
+ switch (do_background)
+ {
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
+ case PNG_BACKGROUND_GAMMA_SCREEN:
+ case PNG_BACKGROUND_GAMMA_FILE:
+ case PNG_BACKGROUND_GAMMA_UNIQUE:
+ /* Standard PNG background processing. */
+ if (alpha < 1)
+ {
+ if (alpha > 0)
+ {
+ input_sample = input_sample * alpha + background * (1-alpha);
+ if (compose != NULL)
+ *compose = 1;
+ }
+
+ else
+ input_sample = background;
+ }
+ break;
+#endif
+
+#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
+ case ALPHA_MODE_OFFSET + PNG_ALPHA_STANDARD:
+ case ALPHA_MODE_OFFSET + PNG_ALPHA_BROKEN:
+ /* The components are premultiplied in either case and the output is
+ * gamma encoded (to get standard Porter-Duff we expect the output
+ * gamma to be set to 1.0!)
+ */
+ case ALPHA_MODE_OFFSET + PNG_ALPHA_OPTIMIZED:
+ /* The optimization is that the partial-alpha entries are linear
+ * while the opaque pixels are gamma encoded, but this only affects the
+ * output encoding.
+ */
+ if (alpha < 1)
+ {
+ if (alpha > 0)
+ {
+ input_sample *= alpha;
+ if (compose != NULL)
+ *compose = 1;
+ }
+
+ else
+ input_sample = 0;
+ }
+ break;
+#endif
+
+ default:
+ /* Standard cases where no compositing is done (so the component
+ * value is already correct.)
+ */
+ UNUSED(alpha)
+ UNUSED(background)
+ UNUSED(compose)
+ break;
+ }
+
+ return input_sample;
+}
+
+/* This API returns the encoded *input* component, in the range 0..1 */
+static double
+gamma_component_validate(const char *name, const validate_info *vi,
+ const unsigned int id, const unsigned int od,
+ const double alpha /* <0 for the alpha channel itself */,
+ const double background /* component background value */)
+{
+ const unsigned int isbit = id >> vi->isbit_shift;
+ const unsigned int sbit_max = vi->sbit_max;
+ const unsigned int outmax = vi->outmax;
+ const int do_background = vi->do_background;
+
+ double i;
+
+ /* First check on the 'perfect' result obtained from the digitized input
+ * value, id, and compare this against the actual digitized result, 'od'.
+ * 'i' is the input result in the range 0..1:
+ */
+ i = isbit; i /= sbit_max;
+
+ /* Check for the fast route: if we don't do any background composition or if
+ * this is the alpha channel ('alpha' < 0) or if the pixel is opaque then
+ * just use the gamma_correction field to correct to the final output gamma.
+ */
+ if (alpha == 1 /* opaque pixel component */ || !do_background
+#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
+ || do_background == ALPHA_MODE_OFFSET + PNG_ALPHA_PNG
+#endif
+ || (alpha < 0 /* alpha channel */
+#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
+ && do_background != ALPHA_MODE_OFFSET + PNG_ALPHA_BROKEN
+#endif
+ ))
+ {
+ /* Then get the gamma corrected version of 'i' and compare to 'od', any
+ * error less than .5 is insignificant - just quantization of the output
+ * value to the nearest digital value (nevertheless the error is still
+ * recorded - it's interesting ;-)
+ */
+ double encoded_sample = i;
+ double encoded_error;
+
+ /* alpha less than 0 indicates the alpha channel, which is always linear
+ */
+ if (alpha >= 0 && vi->gamma_correction > 0)
+ encoded_sample = pow(encoded_sample, vi->gamma_correction);
+ encoded_sample *= outmax;
+
+ encoded_error = fabs(od-encoded_sample);
+
+ if (encoded_error > vi->dp->maxerrout)
+ vi->dp->maxerrout = encoded_error;
+
+ if (encoded_error < vi->maxout_total && encoded_error < vi->outlog)
+ return i;
+ }
+
+ /* The slow route - attempt to do linear calculations. */
+ /* There may be an error, or background processing is required, so calculate
+ * the actual sample values - unencoded light intensity values. Note that in
+ * practice these are not completely unencoded because they include a
+ * 'viewing correction' to decrease or (normally) increase the perceptual
+ * contrast of the image. There's nothing we can do about this - we don't
+ * know what it is - so assume the unencoded value is perceptually linear.
+ */
+ {
+ double input_sample = i; /* In range 0..1 */
+ double output, error, encoded_sample, encoded_error;
+ double es_lo, es_hi;
+ int compose = 0; /* Set to one if composition done */
+ int output_is_encoded; /* Set if encoded to screen gamma */
+ int log_max_error = 1; /* Check maximum error values */
+ png_const_charp pass = 0; /* Reason test passes (or 0 for fail) */
+
+ /* Convert to linear light (with the above caveat.) The alpha channel is
+ * already linear.
+ */
+ if (alpha >= 0)
+ {
+ int tcompose;
+
+ if (vi->file_inverse > 0)
+ input_sample = pow(input_sample, vi->file_inverse);
+
+ /* Handle the compose processing: */
+ tcompose = 0;
+ input_sample = gamma_component_compose(do_background, input_sample,
+ alpha, background, &tcompose);
+
+ if (tcompose)
+ compose = 1;
+ }
+
+ /* And similarly for the output value, but we need to check the background
+ * handling to linearize it correctly.
+ */
+ output = od;
+ output /= outmax;
+
+ output_is_encoded = vi->screen_gamma > 0;
+
+ if (alpha < 0) /* The alpha channel */
+ {
+#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
+ if (do_background != ALPHA_MODE_OFFSET + PNG_ALPHA_BROKEN)
+#endif
+ {
+ /* In all other cases the output alpha channel is linear already,
+ * don't log errors here, they are much larger in linear data.
+ */
+ output_is_encoded = 0;
+ log_max_error = 0;
+ }
+ }
+
+#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
+ else /* A component */
+ {
+ if (do_background == ALPHA_MODE_OFFSET + PNG_ALPHA_OPTIMIZED &&
+ alpha < 1) /* the optimized case - linear output */
+ {
+ if (alpha > 0) log_max_error = 0;
+ output_is_encoded = 0;
+ }
+ }
+#endif
+
+ if (output_is_encoded)
+ output = pow(output, vi->screen_gamma);
+
+ /* Calculate (or recalculate) the encoded_sample value and repeat the
+ * check above (unnecessary if we took the fast route, but harmless.)
+ */
+ encoded_sample = input_sample;
+ if (output_is_encoded)
+ encoded_sample = pow(encoded_sample, vi->screen_inverse);
+ encoded_sample *= outmax;
+
+ encoded_error = fabs(od-encoded_sample);
+
+ /* Don't log errors in the alpha channel, or the 'optimized' case,
+ * neither are significant to the overall perception.
+ */
+ if (log_max_error && encoded_error > vi->dp->maxerrout)
+ vi->dp->maxerrout = encoded_error;
+
+ if (encoded_error < vi->maxout_total)
+ {
+ if (encoded_error < vi->outlog)
+ return i;
+
+ /* Test passed but error is bigger than the log limit, record why the
+ * test passed:
+ */
+ pass = "less than maxout:\n";
+ }
+
+ /* i: the original input value in the range 0..1
+ *
+ * pngvalid calculations:
+ * input_sample: linear result; i linearized and composed, range 0..1
+ * encoded_sample: encoded result; input_sample scaled to ouput bit depth
+ *
+ * libpng calculations:
+ * output: linear result; od scaled to 0..1 and linearized
+ * od: encoded result from libpng
+ */
+
+ /* Now we have the numbers for real errors, both absolute values as as a
+ * percentage of the correct value (output):
+ */
+ error = fabs(input_sample-output);
+
+ if (log_max_error && error > vi->dp->maxerrabs)
+ vi->dp->maxerrabs = error;
+
+ /* The following is an attempt to ignore the tendency of quantization to
+ * dominate the percentage errors for lower result values:
+ */
+ if (log_max_error && input_sample > .5)
+ {
+ double percentage_error = error/input_sample;
+ if (percentage_error > vi->dp->maxerrpc)
+ vi->dp->maxerrpc = percentage_error;
+ }
+
+ /* Now calculate the digitization limits for 'encoded_sample' using the
+ * 'max' values. Note that maxout is in the encoded space but maxpc and
+ * maxabs are in linear light space.
+ *
+ * First find the maximum error in linear light space, range 0..1:
+ */
+ {
+ double tmp = input_sample * vi->maxpc;
+ if (tmp < vi->maxabs) tmp = vi->maxabs;
+ /* If 'compose' is true the composition was done in linear space using
+ * integer arithmetic. This introduces an extra error of +/- 0.5 (at
+ * least) in the integer space used. 'maxcalc' records this, taking
+ * into account the possibility that even for 16 bit output 8 bit space
+ * may have been used.
+ */
+ if (compose && tmp < vi->maxcalc) tmp = vi->maxcalc;
+
+ /* The 'maxout' value refers to the encoded result, to compare with
+ * this encode input_sample adjusted by the maximum error (tmp) above.
+ */
+ es_lo = encoded_sample - vi->maxout;
+
+ if (es_lo > 0 && input_sample-tmp > 0)
+ {
+ double low_value = input_sample-tmp;
+ if (output_is_encoded)
+ low_value = pow(low_value, vi->screen_inverse);
+ low_value *= outmax;
+ if (low_value < es_lo) es_lo = low_value;
+
+ /* Quantize this appropriately: */
+ es_lo = ceil(es_lo / vi->outquant - .5) * vi->outquant;
+ }
+
+ else
+ es_lo = 0;
+
+ es_hi = encoded_sample + vi->maxout;
+
+ if (es_hi < outmax && input_sample+tmp < 1)
+ {
+ double high_value = input_sample+tmp;
+ if (output_is_encoded)
+ high_value = pow(high_value, vi->screen_inverse);
+ high_value *= outmax;
+ if (high_value > es_hi) es_hi = high_value;
+
+ es_hi = floor(es_hi / vi->outquant + .5) * vi->outquant;
+ }
+
+ else
+ es_hi = outmax;
+ }
+
+ /* The primary test is that the final encoded value returned by the
+ * library should be between the two limits (inclusive) that were
+ * calculated above.
+ */
+ if (od >= es_lo && od <= es_hi)
+ {
+ /* The value passes, but we may need to log the information anyway. */
+ if (encoded_error < vi->outlog)
+ return i;
+
+ if (pass == 0)
+ pass = "within digitization limits:\n";
+ }
+
+ {
+ /* There has been an error in processing, or we need to log this
+ * value.
+ */
+ double is_lo, is_hi;
+
+ /* pass is set at this point if either of the tests above would have
+ * passed. Don't do these additional tests here - just log the
+ * original [es_lo..es_hi] values.
+ */
+ if (pass == 0 && vi->use_input_precision && vi->dp->sbit)
+ {
+ /* Ok, something is wrong - this actually happens in current libpng
+ * 16-to-8 processing. Assume that the input value (id, adjusted
+ * for sbit) can be anywhere between value-.5 and value+.5 - quite a
+ * large range if sbit is low.
+ *
+ * NOTE: at present because the libpng gamma table stuff has been
+ * changed to use a rounding algorithm to correct errors in 8-bit
+ * calculations the precise sbit calculation (a shift) has been
+ * lost. This can result in up to a +/-1 error in the presence of
+ * an sbit less than the bit depth.
+ */
+# if PNG_LIBPNG_VER < 10700
+# define SBIT_ERROR .5
+# else
+# define SBIT_ERROR 1.
+# endif
+ double tmp = (isbit - SBIT_ERROR)/sbit_max;
+
+ if (tmp <= 0)
+ tmp = 0;
+
+ else if (alpha >= 0 && vi->file_inverse > 0 && tmp < 1)
+ tmp = pow(tmp, vi->file_inverse);
+
+ tmp = gamma_component_compose(do_background, tmp, alpha, background,
+ NULL);
+
+ if (output_is_encoded && tmp > 0 && tmp < 1)
+ tmp = pow(tmp, vi->screen_inverse);
+
+ is_lo = ceil(outmax * tmp - vi->maxout_total);
+
+ if (is_lo < 0)
+ is_lo = 0;
+
+ tmp = (isbit + SBIT_ERROR)/sbit_max;
+
+ if (tmp >= 1)
+ tmp = 1;
+
+ else if (alpha >= 0 && vi->file_inverse > 0 && tmp < 1)
+ tmp = pow(tmp, vi->file_inverse);
+
+ tmp = gamma_component_compose(do_background, tmp, alpha, background,
+ NULL);
+
+ if (output_is_encoded && tmp > 0 && tmp < 1)
+ tmp = pow(tmp, vi->screen_inverse);
+
+ is_hi = floor(outmax * tmp + vi->maxout_total);
+
+ if (is_hi > outmax)
+ is_hi = outmax;
+
+ if (!(od < is_lo || od > is_hi))
+ {
+ if (encoded_error < vi->outlog)
+ return i;
+
+ pass = "within input precision limits:\n";
+ }
+
+ /* One last chance. If this is an alpha channel and the 16to8
+ * option has been used and 'inaccurate' scaling is used then the
+ * bit reduction is obtained by simply using the top 8 bits of the
+ * value.
+ *
+ * This is only done for older libpng versions when the 'inaccurate'
+ * (chop) method of scaling was used.
+ */
+# ifndef PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
+# if PNG_LIBPNG_VER < 10504
+ /* This may be required for other components in the future,
+ * but at present the presence of gamma correction effectively
+ * prevents the errors in the component scaling (I don't quite
+ * understand why, but since it's better this way I care not
+ * to ask, JB 20110419.)
+ */
+ if (pass == 0 && alpha < 0 && vi->scale16 && vi->sbit > 8 &&
+ vi->sbit + vi->isbit_shift == 16)
+ {
+ tmp = ((id >> 8) - .5)/255;
+
+ if (tmp > 0)
+ {
+ is_lo = ceil(outmax * tmp - vi->maxout_total);
+ if (is_lo < 0) is_lo = 0;
+ }
+
+ else
+ is_lo = 0;
+
+ tmp = ((id >> 8) + .5)/255;
+
+ if (tmp < 1)
+ {
+ is_hi = floor(outmax * tmp + vi->maxout_total);
+ if (is_hi > outmax) is_hi = outmax;
+ }
+
+ else
+ is_hi = outmax;
+
+ if (!(od < is_lo || od > is_hi))
+ {
+ if (encoded_error < vi->outlog)
+ return i;
+
+ pass = "within 8 bit limits:\n";
+ }
+ }
+# endif
+# endif
+ }
+ else /* !use_input_precision */
+ is_lo = es_lo, is_hi = es_hi;
+
+ /* Attempt to output a meaningful error/warning message: the message
+ * output depends on the background/composite operation being performed
+ * because this changes what parameters were actually used above.
+ */
+ {
+ size_t pos = 0;
+ /* Need either 1/255 or 1/65535 precision here; 3 or 6 decimal
+ * places. Just use outmax to work out which.
+ */
+ int precision = (outmax >= 1000 ? 6 : 3);
+ int use_input=1, use_background=0, do_compose=0;
+ char msg[256];
+
+ if (pass != 0)
+ pos = safecat(msg, sizeof msg, pos, "\n\t");
+
+ /* Set up the various flags, the output_is_encoded flag above
+ * is also used below. do_compose is just a double check.
+ */
+ switch (do_background)
+ {
+# ifdef PNG_READ_BACKGROUND_SUPPORTED
+ case PNG_BACKGROUND_GAMMA_SCREEN:
+ case PNG_BACKGROUND_GAMMA_FILE:
+ case PNG_BACKGROUND_GAMMA_UNIQUE:
+ use_background = (alpha >= 0 && alpha < 1);
+ /*FALL THROUGH*/
+# endif
+# ifdef PNG_READ_ALPHA_MODE_SUPPORTED
+ case ALPHA_MODE_OFFSET + PNG_ALPHA_STANDARD:
+ case ALPHA_MODE_OFFSET + PNG_ALPHA_BROKEN:
+ case ALPHA_MODE_OFFSET + PNG_ALPHA_OPTIMIZED:
+# endif /* ALPHA_MODE_SUPPORTED */
+ do_compose = (alpha > 0 && alpha < 1);
+ use_input = (alpha != 0);
+ break;
+
+ default:
+ break;
+ }
+
+ /* Check the 'compose' flag */
+ if (compose != do_compose)
+ png_error(vi->pp, "internal error (compose)");
+
+ /* 'name' is the component name */
+ pos = safecat(msg, sizeof msg, pos, name);
+ pos = safecat(msg, sizeof msg, pos, "(");
+ pos = safecatn(msg, sizeof msg, pos, id);
+ if (use_input || pass != 0/*logging*/)
+ {
+ if (isbit != id)
+ {
+ /* sBIT has reduced the precision of the input: */
+ pos = safecat(msg, sizeof msg, pos, ", sbit(");
+ pos = safecatn(msg, sizeof msg, pos, vi->sbit);
+ pos = safecat(msg, sizeof msg, pos, "): ");
+ pos = safecatn(msg, sizeof msg, pos, isbit);
+ }
+ pos = safecat(msg, sizeof msg, pos, "/");
+ /* The output is either "id/max" or "id sbit(sbit): isbit/max" */
+ pos = safecatn(msg, sizeof msg, pos, vi->sbit_max);
+ }
+ pos = safecat(msg, sizeof msg, pos, ")");
+
+ /* A component may have been multiplied (in linear space) by the
+ * alpha value, 'compose' says whether this is relevant.
+ */
+ if (compose || pass != 0)
+ {
+ /* If any form of composition is being done report our
+ * calculated linear value here (the code above doesn't record
+ * the input value before composition is performed, so what
+ * gets reported is the value after composition.)
+ */
+ if (use_input || pass != 0)
+ {
+ if (vi->file_inverse > 0)
+ {
+ pos = safecat(msg, sizeof msg, pos, "^");
+ pos = safecatd(msg, sizeof msg, pos, vi->file_inverse, 2);
+ }
+
+ else
+ pos = safecat(msg, sizeof msg, pos, "[linear]");
+
+ pos = safecat(msg, sizeof msg, pos, "*(alpha)");
+ pos = safecatd(msg, sizeof msg, pos, alpha, precision);
+ }
+
+ /* Now record the *linear* background value if it was used
+ * (this function is not passed the original, non-linear,
+ * value but it is contained in the test name.)
+ */
+ if (use_background)
+ {
+ pos = safecat(msg, sizeof msg, pos, use_input ? "+" : " ");
+ pos = safecat(msg, sizeof msg, pos, "(background)");
+ pos = safecatd(msg, sizeof msg, pos, background, precision);
+ pos = safecat(msg, sizeof msg, pos, "*");
+ pos = safecatd(msg, sizeof msg, pos, 1-alpha, precision);
+ }
+ }
+
+ /* Report the calculated value (input_sample) and the linearized
+ * libpng value (output) unless this is just a component gamma
+ * correction.
+ */
+ if (compose || alpha < 0 || pass != 0)
+ {
+ pos = safecat(msg, sizeof msg, pos,
+ pass != 0 ? " =\n\t" : " = ");
+ pos = safecatd(msg, sizeof msg, pos, input_sample, precision);
+ pos = safecat(msg, sizeof msg, pos, " (libpng: ");
+ pos = safecatd(msg, sizeof msg, pos, output, precision);
+ pos = safecat(msg, sizeof msg, pos, ")");
+
+ /* Finally report the output gamma encoding, if any. */
+ if (output_is_encoded)
+ {
+ pos = safecat(msg, sizeof msg, pos, " ^");
+ pos = safecatd(msg, sizeof msg, pos, vi->screen_inverse, 2);
+ pos = safecat(msg, sizeof msg, pos, "(to screen) =");
+ }
+
+ else
+ pos = safecat(msg, sizeof msg, pos, " [screen is linear] =");
+ }
+
+ if ((!compose && alpha >= 0) || pass != 0)
+ {
+ if (pass != 0) /* logging */
+ pos = safecat(msg, sizeof msg, pos, "\n\t[overall:");
+
+ /* This is the non-composition case, the internal linear
+ * values are irrelevant (though the log below will reveal
+ * them.) Output a much shorter warning/error message and report
+ * the overall gamma correction.
+ */
+ if (vi->gamma_correction > 0)
+ {
+ pos = safecat(msg, sizeof msg, pos, " ^");
+ pos = safecatd(msg, sizeof msg, pos, vi->gamma_correction, 2);
+ pos = safecat(msg, sizeof msg, pos, "(gamma correction) =");
+ }
+
+ else
+ pos = safecat(msg, sizeof msg, pos,
+ " [no gamma correction] =");
+
+ if (pass != 0)
+ pos = safecat(msg, sizeof msg, pos, "]");
+ }
+
+ /* This is our calculated encoded_sample which should (but does
+ * not) match od:
+ */
+ pos = safecat(msg, sizeof msg, pos, pass != 0 ? "\n\t" : " ");
+ pos = safecatd(msg, sizeof msg, pos, is_lo, 1);
+ pos = safecat(msg, sizeof msg, pos, " < ");
+ pos = safecatd(msg, sizeof msg, pos, encoded_sample, 1);
+ pos = safecat(msg, sizeof msg, pos, " (libpng: ");
+ pos = safecatn(msg, sizeof msg, pos, od);
+ pos = safecat(msg, sizeof msg, pos, ")");
+ pos = safecat(msg, sizeof msg, pos, "/");
+ pos = safecatn(msg, sizeof msg, pos, outmax);
+ pos = safecat(msg, sizeof msg, pos, " < ");
+ pos = safecatd(msg, sizeof msg, pos, is_hi, 1);
+
+ if (pass == 0) /* The error condition */
+ {
+# ifdef PNG_WARNINGS_SUPPORTED
+ png_warning(vi->pp, msg);
+# else
+ store_warning(vi->pp, msg);
+# endif
+ }
+
+ else /* logging this value */
+ store_verbose(&vi->dp->pm->this, vi->pp, pass, msg);
+ }
+ }
+ }
+
+ return i;
+}
+
+static void
+gamma_image_validate(gamma_display *dp, png_const_structp pp,
+ png_infop pi)
+{
+ /* Get some constants derived from the input and output file formats: */
+ const png_store* const ps = dp->this.ps;
+ const png_byte in_ct = dp->this.colour_type;
+ const png_byte in_bd = dp->this.bit_depth;
+ const png_uint_32 w = dp->this.w;
+ const png_uint_32 h = dp->this.h;
+ const size_t cbRow = dp->this.cbRow;
+ const png_byte out_ct = png_get_color_type(pp, pi);
+ const png_byte out_bd = png_get_bit_depth(pp, pi);
+
+ /* There are three sources of error, firstly the quantization in the
+ * file encoding, determined by sbit and/or the file depth, secondly
+ * the output (screen) gamma and thirdly the output file encoding.
+ *
+ * Since this API receives the screen and file gamma in double
+ * precision it is possible to calculate an exact answer given an input
+ * pixel value. Therefore we assume that the *input* value is exact -
+ * sample/maxsample - calculate the corresponding gamma corrected
+ * output to the limits of double precision arithmetic and compare with
+ * what libpng returns.
+ *
+ * Since the library must quantize the output to 8 or 16 bits there is
+ * a fundamental limit on the accuracy of the output of +/-.5 - this
+ * quantization limit is included in addition to the other limits
+ * specified by the paramaters to the API. (Effectively, add .5
+ * everywhere.)
+ *
+ * The behavior of the 'sbit' paramter is defined by section 12.5
+ * (sample depth scaling) of the PNG spec. That section forces the
+ * decoder to assume that the PNG values have been scaled if sBIT is
+ * present:
+ *
+ * png-sample = floor( input-sample * (max-out/max-in) + .5);
+ *
+ * This means that only a subset of the possible PNG values should
+ * appear in the input. However, the spec allows the encoder to use a
+ * variety of approximations to the above and doesn't require any
+ * restriction of the values produced.
+ *
+ * Nevertheless the spec requires that the upper 'sBIT' bits of the
+ * value stored in a PNG file be the original sample bits.
+ * Consequently the code below simply scales the top sbit bits by
+ * (1<<sbit)-1 to obtain an original sample value.
+ *
+ * Because there is limited precision in the input it is arguable that
+ * an acceptable result is any valid result from input-.5 to input+.5.
+ * The basic tests below do not do this, however if 'use_input_precision'
+ * is set a subsequent test is performed above.
+ */
+ const unsigned int samples_per_pixel = (out_ct & 2U) ? 3U : 1U;
+ int processing;
+ png_uint_32 y;
+ const store_palette_entry *in_palette = dp->this.palette;
+ const int in_is_transparent = dp->this.is_transparent;
+ int process_tRNS;
+ int out_npalette = -1;
+ int out_is_transparent = 0; /* Just refers to the palette case */
+ store_palette out_palette;
+ validate_info vi;
+
+ /* Check for row overwrite errors */
+ store_image_check(dp->this.ps, pp, 0);
+
+ /* Supply the input and output sample depths here - 8 for an indexed image,
+ * otherwise the bit depth.
+ */
+ init_validate_info(&vi, dp, pp, in_ct==3?8:in_bd, out_ct==3?8:out_bd);
+
+ processing = (vi.gamma_correction > 0 && !dp->threshold_test)
+ || in_bd != out_bd || in_ct != out_ct || vi.do_background;
+ process_tRNS = dp->this.has_tRNS && vi.do_background;
+
+ /* TODO: FIX THIS: MAJOR BUG! If the transformations all happen inside
+ * the palette there is no way of finding out, because libpng fails to
+ * update the palette on png_read_update_info. Indeed, libpng doesn't
+ * even do the required work until much later, when it doesn't have any
+ * info pointer. Oops. For the moment 'processing' is turned off if
+ * out_ct is palette.
+ */
+ if (in_ct == 3 && out_ct == 3)
+ processing = 0;
+
+ if (processing && out_ct == 3)
+ out_is_transparent = read_palette(out_palette, &out_npalette, pp, pi);
+
+ for (y=0; y<h; ++y)
+ {
+ png_const_bytep pRow = store_image_row(ps, pp, 0, y);
+ png_byte std[STANDARD_ROWMAX];
+
+ transform_row(pp, std, in_ct, in_bd, y);
+
+ if (processing)
+ {
+ unsigned int x;
+
+ for (x=0; x<w; ++x)
+ {
+ double alpha = 1; /* serves as a flag value */
+
+ /* Record the palette index for index images. */
+ const unsigned int in_index =
+ in_ct == 3 ? sample(std, 3, in_bd, x, 0, 0, 0) : 256;
+ const unsigned int out_index =
+ out_ct == 3 ? sample(std, 3, out_bd, x, 0, 0, 0) : 256;
+
+ /* Handle input alpha - png_set_background will cause the output
+ * alpha to disappear so there is nothing to check.
+ */
+ if ((in_ct & PNG_COLOR_MASK_ALPHA) != 0 ||
+ (in_ct == 3 && in_is_transparent))
+ {
+ const unsigned int input_alpha = in_ct == 3 ?
+ dp->this.palette[in_index].alpha :
+ sample(std, in_ct, in_bd, x, samples_per_pixel, 0, 0);
+
+ unsigned int output_alpha = 65536 /* as a flag value */;
+
+ if (out_ct == 3)
+ {
+ if (out_is_transparent)
+ output_alpha = out_palette[out_index].alpha;
+ }
+
+ else if ((out_ct & PNG_COLOR_MASK_ALPHA) != 0)
+ output_alpha = sample(pRow, out_ct, out_bd, x,
+ samples_per_pixel, 0, 0);
+
+ if (output_alpha != 65536)
+ alpha = gamma_component_validate("alpha", &vi, input_alpha,
+ output_alpha, -1/*alpha*/, 0/*background*/);
+
+ else /* no alpha in output */
+ {
+ /* This is a copy of the calculation of 'i' above in order to
+ * have the alpha value to use in the background calculation.
+ */
+ alpha = input_alpha >> vi.isbit_shift;
+ alpha /= vi.sbit_max;
+ }
+ }
+
+ else if (process_tRNS)
+ {
+ /* alpha needs to be set appropriately for this pixel, it is
+ * currently 1 and needs to be 0 for an input pixel which matches
+ * the values in tRNS.
+ */
+ switch (in_ct)
+ {
+ case 0: /* gray */
+ if (sample(std, in_ct, in_bd, x, 0, 0, 0) ==
+ dp->this.transparent.red)
+ alpha = 0;
+ break;
+
+ case 2: /* RGB */
+ if (sample(std, in_ct, in_bd, x, 0, 0, 0) ==
+ dp->this.transparent.red &&
+ sample(std, in_ct, in_bd, x, 1, 0, 0) ==
+ dp->this.transparent.green &&
+ sample(std, in_ct, in_bd, x, 2, 0, 0) ==
+ dp->this.transparent.blue)
+ alpha = 0;
+ break;
+
+ default:
+ break;
+ }
+ }
+
+ /* Handle grayscale or RGB components. */
+ if ((in_ct & PNG_COLOR_MASK_COLOR) == 0) /* grayscale */
+ (void)gamma_component_validate("gray", &vi,
+ sample(std, in_ct, in_bd, x, 0, 0, 0),
+ sample(pRow, out_ct, out_bd, x, 0, 0, 0),
+ alpha/*component*/, vi.background_red);
+ else /* RGB or palette */
+ {
+ (void)gamma_component_validate("red", &vi,
+ in_ct == 3 ? in_palette[in_index].red :
+ sample(std, in_ct, in_bd, x, 0, 0, 0),
+ out_ct == 3 ? out_palette[out_index].red :
+ sample(pRow, out_ct, out_bd, x, 0, 0, 0),
+ alpha/*component*/, vi.background_red);
+
+ (void)gamma_component_validate("green", &vi,
+ in_ct == 3 ? in_palette[in_index].green :
+ sample(std, in_ct, in_bd, x, 1, 0, 0),
+ out_ct == 3 ? out_palette[out_index].green :
+ sample(pRow, out_ct, out_bd, x, 1, 0, 0),
+ alpha/*component*/, vi.background_green);
+
+ (void)gamma_component_validate("blue", &vi,
+ in_ct == 3 ? in_palette[in_index].blue :
+ sample(std, in_ct, in_bd, x, 2, 0, 0),
+ out_ct == 3 ? out_palette[out_index].blue :
+ sample(pRow, out_ct, out_bd, x, 2, 0, 0),
+ alpha/*component*/, vi.background_blue);
+ }
+ }
+ }
+
+ else if (memcmp(std, pRow, cbRow) != 0)
+ {
+ char msg[64];
+
+ /* No transform is expected on the threshold tests. */
+ sprintf(msg, "gamma: below threshold row %lu changed",
+ (unsigned long)y);
+
+ png_error(pp, msg);
+ }
+ } /* row (y) loop */
+
+ dp->this.ps->validated = 1;
+}
+
+static void PNGCBAPI
+gamma_end(png_structp ppIn, png_infop pi)
+{
+ png_const_structp pp = ppIn;
+ gamma_display *dp = voidcast(gamma_display*, png_get_progressive_ptr(pp));
+
+ if (!dp->this.speed)
+ gamma_image_validate(dp, pp, pi);
+ else
+ dp->this.ps->validated = 1;
+}
+
+/* A single test run checking a gamma transformation.
+ *
+ * maxabs: maximum absolute error as a fraction
+ * maxout: maximum output error in the output units
+ * maxpc: maximum percentage error (as a percentage)
+ */
+static void
+gamma_test(png_modifier *pmIn, const png_byte colour_typeIn,
+ const png_byte bit_depthIn, const int palette_numberIn,
+ const int interlace_typeIn,
+ const double file_gammaIn, const double screen_gammaIn,
+ const png_byte sbitIn, const int threshold_testIn,
+ const char *name,
+ const int use_input_precisionIn, const int scale16In,
+ const int expand16In, const int do_backgroundIn,
+ const png_color_16 *bkgd_colorIn, double bkgd_gammaIn)
+{
+ gamma_display d;
+ context(&pmIn->this, fault);
+
+ gamma_display_init(&d, pmIn, FILEID(colour_typeIn, bit_depthIn,
+ palette_numberIn, interlace_typeIn, 0, 0, 0),
+ file_gammaIn, screen_gammaIn, sbitIn,
+ threshold_testIn, use_input_precisionIn, scale16In,
+ expand16In, do_backgroundIn, bkgd_colorIn, bkgd_gammaIn);
+
+ Try
+ {
+ png_structp pp;
+ png_infop pi;
+ gama_modification gama_mod;
+ srgb_modification srgb_mod;
+ sbit_modification sbit_mod;
+
+ /* For the moment don't use the png_modifier support here. */
+ d.pm->encoding_counter = 0;
+ modifier_set_encoding(d.pm); /* Just resets everything */
+ d.pm->current_gamma = d.file_gamma;
+
+ /* Make an appropriate modifier to set the PNG file gamma to the
+ * given gamma value and the sBIT chunk to the given precision.
+ */
+ d.pm->modifications = NULL;
+ gama_modification_init(&gama_mod, d.pm, d.file_gamma);
+ srgb_modification_init(&srgb_mod, d.pm, 127 /*delete*/);
+ if (d.sbit > 0)
+ sbit_modification_init(&sbit_mod, d.pm, d.sbit);
+
+ modification_reset(d.pm->modifications);
+
+ /* Get a png_struct for reading the image. */
+ pp = set_modifier_for_read(d.pm, &pi, d.this.id, name);
+ standard_palette_init(&d.this);
+
+ /* Introduce the correct read function. */
+ if (d.pm->this.progressive)
+ {
+ /* Share the row function with the standard implementation. */
+ png_set_progressive_read_fn(pp, &d, gamma_info, progressive_row,
+ gamma_end);
+
+ /* Now feed data into the reader until we reach the end: */
+ modifier_progressive_read(d.pm, pp, pi);
+ }
+ else
+ {
+ /* modifier_read expects a png_modifier* */
+ png_set_read_fn(pp, d.pm, modifier_read);
+
+ /* Check the header values: */
+ png_read_info(pp, pi);
+
+ /* Process the 'info' requirements. Only one image is generated */
+ gamma_info_imp(&d, pp, pi);
+
+ sequential_row(&d.this, pp, pi, -1, 0);
+
+ if (!d.this.speed)
+ gamma_image_validate(&d, pp, pi);
+ else
+ d.this.ps->validated = 1;
+ }
+
+ modifier_reset(d.pm);
+
+ if (d.pm->log && !d.threshold_test && !d.this.speed)
+ fprintf(stderr, "%d bit %s %s: max error %f (%.2g, %2g%%)\n",
+ d.this.bit_depth, colour_types[d.this.colour_type], name,
+ d.maxerrout, d.maxerrabs, 100*d.maxerrpc);
+
+ /* Log the summary values too. */
+ if (d.this.colour_type == 0 || d.this.colour_type == 4)
+ {
+ switch (d.this.bit_depth)
+ {
+ case 1:
+ break;
+
+ case 2:
+ if (d.maxerrout > d.pm->error_gray_2)
+ d.pm->error_gray_2 = d.maxerrout;
+
+ break;
+
+ case 4:
+ if (d.maxerrout > d.pm->error_gray_4)
+ d.pm->error_gray_4 = d.maxerrout;
+
+ break;
+
+ case 8:
+ if (d.maxerrout > d.pm->error_gray_8)
+ d.pm->error_gray_8 = d.maxerrout;
+
+ break;
+
+ case 16:
+ if (d.maxerrout > d.pm->error_gray_16)
+ d.pm->error_gray_16 = d.maxerrout;
+
+ break;
+
+ default:
+ png_error(pp, "bad bit depth (internal: 1)");
+ }
+ }
+
+ else if (d.this.colour_type == 2 || d.this.colour_type == 6)
+ {
+ switch (d.this.bit_depth)
+ {
+ case 8:
+
+ if (d.maxerrout > d.pm->error_color_8)
+ d.pm->error_color_8 = d.maxerrout;
+
+ break;
+
+ case 16:
+
+ if (d.maxerrout > d.pm->error_color_16)
+ d.pm->error_color_16 = d.maxerrout;
+
+ break;
+
+ default:
+ png_error(pp, "bad bit depth (internal: 2)");
+ }
+ }
+
+ else if (d.this.colour_type == 3)
+ {
+ if (d.maxerrout > d.pm->error_indexed)
+ d.pm->error_indexed = d.maxerrout;
+ }
+ }
+
+ Catch(fault)
+ modifier_reset(voidcast(png_modifier*,(void*)fault));
+}
+
+static void gamma_threshold_test(png_modifier *pm, png_byte colour_type,
+ png_byte bit_depth, int interlace_type, double file_gamma,
+ double screen_gamma)
+{
+ size_t pos = 0;
+ char name[64];
+ pos = safecat(name, sizeof name, pos, "threshold ");
+ pos = safecatd(name, sizeof name, pos, file_gamma, 3);
+ pos = safecat(name, sizeof name, pos, "/");
+ pos = safecatd(name, sizeof name, pos, screen_gamma, 3);
+
+ (void)gamma_test(pm, colour_type, bit_depth, 0/*palette*/, interlace_type,
+ file_gamma, screen_gamma, 0/*sBIT*/, 1/*threshold test*/, name,
+ 0 /*no input precision*/,
+ 0 /*no scale16*/, 0 /*no expand16*/, 0 /*no background*/, 0 /*hence*/,
+ 0 /*no background gamma*/);
+}
+
+static void
+perform_gamma_threshold_tests(png_modifier *pm)
+{
+ png_byte colour_type = 0;
+ png_byte bit_depth = 0;
+ unsigned int palette_number = 0;
+
+ /* Don't test more than one instance of each palette - it's pointless, in
+ * fact this test is somewhat excessive since libpng doesn't make this
+ * decision based on colour type or bit depth!
+ *
+ * CHANGED: now test two palettes and, as a side effect, images with and
+ * without tRNS.
+ */
+ while (next_format(&colour_type, &bit_depth, &palette_number,
+ pm->test_lbg_gamma_threshold, pm->test_tRNS))
+ if (palette_number < 2)
+ {
+ double test_gamma = 1.0;
+ while (test_gamma >= .4)
+ {
+ /* There's little point testing the interlacing vs non-interlacing,
+ * but this can be set from the command line.
+ */
+ gamma_threshold_test(pm, colour_type, bit_depth, pm->interlace_type,
+ test_gamma, 1/test_gamma);
+ test_gamma *= .95;
+ }
+
+ /* And a special test for sRGB */
+ gamma_threshold_test(pm, colour_type, bit_depth, pm->interlace_type,
+ .45455, 2.2);
+
+ if (fail(pm))
+ return;
+ }
+}
+
+static void gamma_transform_test(png_modifier *pm,
+ const png_byte colour_type, const png_byte bit_depth,
+ const int palette_number,
+ const int interlace_type, const double file_gamma,
+ const double screen_gamma, const png_byte sbit,
+ const int use_input_precision, const int scale16)
+{
+ size_t pos = 0;
+ char name[64];
+
+ if (sbit != bit_depth && sbit != 0)
+ {
+ pos = safecat(name, sizeof name, pos, "sbit(");
+ pos = safecatn(name, sizeof name, pos, sbit);
+ pos = safecat(name, sizeof name, pos, ") ");
+ }
+
+ else
+ pos = safecat(name, sizeof name, pos, "gamma ");
+
+ if (scale16)
+ pos = safecat(name, sizeof name, pos, "16to8 ");
+
+ pos = safecatd(name, sizeof name, pos, file_gamma, 3);
+ pos = safecat(name, sizeof name, pos, "->");
+ pos = safecatd(name, sizeof name, pos, screen_gamma, 3);
+
+ gamma_test(pm, colour_type, bit_depth, palette_number, interlace_type,
+ file_gamma, screen_gamma, sbit, 0, name, use_input_precision,
+ scale16, pm->test_gamma_expand16, 0 , 0, 0);
+}
+
+static void perform_gamma_transform_tests(png_modifier *pm)
+{
+ png_byte colour_type = 0;
+ png_byte bit_depth = 0;
+ unsigned int palette_number = 0;
+
+ while (next_format(&colour_type, &bit_depth, &palette_number,
+ pm->test_lbg_gamma_transform, pm->test_tRNS))
+ {
+ unsigned int i, j;
+
+ for (i=0; i<pm->ngamma_tests; ++i) for (j=0; j<pm->ngamma_tests; ++j)
+ if (i != j)
+ {
+ gamma_transform_test(pm, colour_type, bit_depth, palette_number,
+ pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], 0/*sBIT*/,
+ pm->use_input_precision, 0 /*do not scale16*/);
+
+ if (fail(pm))
+ return;
+ }
+ }
+}
+
+static void perform_gamma_sbit_tests(png_modifier *pm)
+{
+ png_byte sbit;
+
+ /* The only interesting cases are colour and grayscale, alpha is ignored here
+ * for overall speed. Only bit depths where sbit is less than the bit depth
+ * are tested.
+ */
+ for (sbit=pm->sbitlow; sbit<(1<<READ_BDHI); ++sbit)
+ {
+ png_byte colour_type = 0, bit_depth = 0;
+ unsigned int npalette = 0;
+
+ while (next_format(&colour_type, &bit_depth, &npalette,
+ pm->test_lbg_gamma_sbit, pm->test_tRNS))
+ if ((colour_type & PNG_COLOR_MASK_ALPHA) == 0 &&
+ ((colour_type == 3 && sbit < 8) ||
+ (colour_type != 3 && sbit < bit_depth)))
+ {
+ unsigned int i;
+
+ for (i=0; i<pm->ngamma_tests; ++i)
+ {
+ unsigned int j;
+
+ for (j=0; j<pm->ngamma_tests; ++j) if (i != j)
+ {
+ gamma_transform_test(pm, colour_type, bit_depth, npalette,
+ pm->interlace_type, 1/pm->gammas[i], pm->gammas[j],
+ sbit, pm->use_input_precision_sbit, 0 /*scale16*/);
+
+ if (fail(pm))
+ return;
+ }
+ }
+ }
+ }
+}
+
+/* Note that this requires a 16 bit source image but produces 8 bit output, so
+ * we only need the 16bit write support, but the 16 bit images are only
+ * generated if DO_16BIT is defined.
+ */
+#ifdef DO_16BIT
+static void perform_gamma_scale16_tests(png_modifier *pm)
+{
+# ifndef PNG_MAX_GAMMA_8
+# define PNG_MAX_GAMMA_8 11
+# endif
+# if defined PNG_MAX_GAMMA_8 || PNG_LIBPNG_VER < 10700
+# define SBIT_16_TO_8 PNG_MAX_GAMMA_8
+# else
+# define SBIT_16_TO_8 16
+# endif
+ /* Include the alpha cases here. Note that sbit matches the internal value
+ * used by the library - otherwise we will get spurious errors from the
+ * internal sbit style approximation.
+ *
+ * The threshold test is here because otherwise the 16 to 8 conversion will
+ * proceed *without* gamma correction, and the tests above will fail (but not
+ * by much) - this could be fixed, it only appears with the -g option.
+ */
+ unsigned int i, j;
+ for (i=0; i<pm->ngamma_tests; ++i)
+ {
+ for (j=0; j<pm->ngamma_tests; ++j)
+ {
+ if (i != j &&
+ fabs(pm->gammas[j]/pm->gammas[i]-1) >= PNG_GAMMA_THRESHOLD)
+ {
+ gamma_transform_test(pm, 0, 16, 0, pm->interlace_type,
+ 1/pm->gammas[i], pm->gammas[j], SBIT_16_TO_8,
+ pm->use_input_precision_16to8, 1 /*scale16*/);
+
+ if (fail(pm))
+ return;
+
+ gamma_transform_test(pm, 2, 16, 0, pm->interlace_type,
+ 1/pm->gammas[i], pm->gammas[j], SBIT_16_TO_8,
+ pm->use_input_precision_16to8, 1 /*scale16*/);
+
+ if (fail(pm))
+ return;
+
+ gamma_transform_test(pm, 4, 16, 0, pm->interlace_type,
+ 1/pm->gammas[i], pm->gammas[j], SBIT_16_TO_8,
+ pm->use_input_precision_16to8, 1 /*scale16*/);
+
+ if (fail(pm))
+ return;
+
+ gamma_transform_test(pm, 6, 16, 0, pm->interlace_type,
+ 1/pm->gammas[i], pm->gammas[j], SBIT_16_TO_8,
+ pm->use_input_precision_16to8, 1 /*scale16*/);
+
+ if (fail(pm))
+ return;
+ }
+ }
+ }
+}
+#endif /* 16 to 8 bit conversion */
+
+#if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
+ defined(PNG_READ_ALPHA_MODE_SUPPORTED)
+static void gamma_composition_test(png_modifier *pm,
+ const png_byte colour_type, const png_byte bit_depth,
+ const int palette_number,
+ const int interlace_type, const double file_gamma,
+ const double screen_gamma,
+ const int use_input_precision, const int do_background,
+ const int expand_16)
+{
+ size_t pos = 0;
+ png_const_charp base;
+ double bg;
+ char name[128];
+ png_color_16 background;
+
+ /* Make up a name and get an appropriate background gamma value. */
+ switch (do_background)
+ {
+ default:
+ base = "";
+ bg = 4; /* should not be used */
+ break;
+ case PNG_BACKGROUND_GAMMA_SCREEN:
+ base = " bckg(Screen):";
+ bg = 1/screen_gamma;
+ break;
+ case PNG_BACKGROUND_GAMMA_FILE:
+ base = " bckg(File):";
+ bg = file_gamma;
+ break;
+ case PNG_BACKGROUND_GAMMA_UNIQUE:
+ base = " bckg(Unique):";
+ /* This tests the handling of a unique value, the math is such that the
+ * value tends to be <1, but is neither screen nor file (even if they
+ * match!)
+ */
+ bg = (file_gamma + screen_gamma) / 3;
+ break;
+#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
+ case ALPHA_MODE_OFFSET + PNG_ALPHA_PNG:
+ base = " alpha(PNG)";
+ bg = 4; /* should not be used */
+ break;
+ case ALPHA_MODE_OFFSET + PNG_ALPHA_STANDARD:
+ base = " alpha(Porter-Duff)";
+ bg = 4; /* should not be used */
+ break;
+ case ALPHA_MODE_OFFSET + PNG_ALPHA_OPTIMIZED:
+ base = " alpha(Optimized)";
+ bg = 4; /* should not be used */
+ break;
+ case ALPHA_MODE_OFFSET + PNG_ALPHA_BROKEN:
+ base = " alpha(Broken)";
+ bg = 4; /* should not be used */
+ break;
+#endif
+ }
+
+ /* Use random background values - the background is always presented in the
+ * output space (8 or 16 bit components).
+ */
+ if (expand_16 || bit_depth == 16)
+ {
+ png_uint_32 r = random_32();
+
+ background.red = (png_uint_16)r;
+ background.green = (png_uint_16)(r >> 16);
+ r = random_32();
+ background.blue = (png_uint_16)r;
+ background.gray = (png_uint_16)(r >> 16);
+
+ /* In earlier libpng versions, those where DIGITIZE is set, any background
+ * gamma correction in the expand16 case was done using 8-bit gamma
+ * correction tables, resulting in larger errors. To cope with those
+ * cases use a 16-bit background value which will handle this gamma
+ * correction.
+ */
+# if DIGITIZE
+ if (expand_16 && (do_background == PNG_BACKGROUND_GAMMA_UNIQUE ||
+ do_background == PNG_BACKGROUND_GAMMA_FILE) &&
+ fabs(bg*screen_gamma-1) > PNG_GAMMA_THRESHOLD)
+ {
+ /* The background values will be looked up in an 8-bit table to do
+ * the gamma correction, so only select values which are an exact
+ * match for the 8-bit table entries:
+ */
+ background.red = (png_uint_16)((background.red >> 8) * 257);
+ background.green = (png_uint_16)((background.green >> 8) * 257);
+ background.blue = (png_uint_16)((background.blue >> 8) * 257);
+ background.gray = (png_uint_16)((background.gray >> 8) * 257);
+ }
+# endif
+ }
+
+ else /* 8 bit colors */
+ {
+ png_uint_32 r = random_32();
+
+ background.red = (png_byte)r;
+ background.green = (png_byte)(r >> 8);
+ background.blue = (png_byte)(r >> 16);
+ background.gray = (png_byte)(r >> 24);
+ }
+
+ background.index = 193; /* rgb(193,193,193) to detect errors */
+
+ if (!(colour_type & PNG_COLOR_MASK_COLOR))
+ {
+ /* Because, currently, png_set_background is always called with
+ * 'need_expand' false in this case and because the gamma test itself
+ * doesn't cause an expand to 8-bit for lower bit depths the colour must
+ * be reduced to the correct range.
+ */
+ if (bit_depth < 8)
+ background.gray &= (png_uint_16)((1U << bit_depth)-1);
+
+ /* Grayscale input, we do not convert to RGB (TBD), so we must set the
+ * background to gray - else libpng seems to fail.
+ */
+ background.red = background.green = background.blue = background.gray;
+ }
+
+ pos = safecat(name, sizeof name, pos, "gamma ");
+ pos = safecatd(name, sizeof name, pos, file_gamma, 3);
+ pos = safecat(name, sizeof name, pos, "->");
+ pos = safecatd(name, sizeof name, pos, screen_gamma, 3);
+
+ pos = safecat(name, sizeof name, pos, base);
+ if (do_background < ALPHA_MODE_OFFSET)
+ {
+ /* Include the background color and gamma in the name: */
+ pos = safecat(name, sizeof name, pos, "(");
+ /* This assumes no expand gray->rgb - the current code won't handle that!
+ */
+ if (colour_type & PNG_COLOR_MASK_COLOR)
+ {
+ pos = safecatn(name, sizeof name, pos, background.red);
+ pos = safecat(name, sizeof name, pos, ",");
+ pos = safecatn(name, sizeof name, pos, background.green);
+ pos = safecat(name, sizeof name, pos, ",");
+ pos = safecatn(name, sizeof name, pos, background.blue);
+ }
+ else
+ pos = safecatn(name, sizeof name, pos, background.gray);
+ pos = safecat(name, sizeof name, pos, ")^");
+ pos = safecatd(name, sizeof name, pos, bg, 3);
+ }
+
+ gamma_test(pm, colour_type, bit_depth, palette_number, interlace_type,
+ file_gamma, screen_gamma, 0/*sBIT*/, 0, name, use_input_precision,
+ 0/*strip 16*/, expand_16, do_background, &background, bg);
+}
+
+
+static void
+perform_gamma_composition_tests(png_modifier *pm, int do_background,
+ int expand_16)
+{
+ png_byte colour_type = 0;
+ png_byte bit_depth = 0;
+ unsigned int palette_number = 0;
+
+ /* Skip the non-alpha cases - there is no setting of a transparency colour at
+ * present.
+ *
+ * TODO: incorrect; the palette case sets tRNS and, now RGB and gray do,
+ * however the palette case fails miserably so is commented out below.
+ */
+ while (next_format(&colour_type, &bit_depth, &palette_number,
+ pm->test_lbg_gamma_composition, pm->test_tRNS))
+ if ((colour_type & PNG_COLOR_MASK_ALPHA) != 0
+#if 0 /* TODO: FIXME */
+ /*TODO: FIXME: this should work */
+ || colour_type == 3
+#endif
+ || (colour_type != 3 && palette_number != 0))
+ {
+ unsigned int i, j;
+
+ /* Don't skip the i==j case here - it's relevant. */
+ for (i=0; i<pm->ngamma_tests; ++i) for (j=0; j<pm->ngamma_tests; ++j)
+ {
+ gamma_composition_test(pm, colour_type, bit_depth, palette_number,
+ pm->interlace_type, 1/pm->gammas[i], pm->gammas[j],
+ pm->use_input_precision, do_background, expand_16);
+
+ if (fail(pm))
+ return;
+ }
+ }
+}
+#endif /* READ_BACKGROUND || READ_ALPHA_MODE */
+
+static void
+init_gamma_errors(png_modifier *pm)
+{
+ /* Use -1 to catch tests that were not actually run */
+ pm->error_gray_2 = pm->error_gray_4 = pm->error_gray_8 = -1.;
+ pm->error_color_8 = -1.;
+ pm->error_indexed = -1.;
+ pm->error_gray_16 = pm->error_color_16 = -1.;
+}
+
+static void
+print_one(const char *leader, double err)
+{
+ if (err != -1.)
+ printf(" %s %.5f\n", leader, err);
+}
+
+static void
+summarize_gamma_errors(png_modifier *pm, png_const_charp who, int low_bit_depth,
+ int indexed)
+{
+ fflush(stderr);
+
+ if (who)
+ printf("\nGamma correction with %s:\n", who);
+
+ else
+ printf("\nBasic gamma correction:\n");
+
+ if (low_bit_depth)
+ {
+ print_one(" 2 bit gray: ", pm->error_gray_2);
+ print_one(" 4 bit gray: ", pm->error_gray_4);
+ print_one(" 8 bit gray: ", pm->error_gray_8);
+ print_one(" 8 bit color:", pm->error_color_8);
+ if (indexed)
+ print_one(" indexed: ", pm->error_indexed);
+ }
+
+ print_one("16 bit gray: ", pm->error_gray_16);
+ print_one("16 bit color:", pm->error_color_16);
+
+ fflush(stdout);
+}
+
+static void
+perform_gamma_test(png_modifier *pm, int summary)
+{
+ /*TODO: remove this*/
+ /* Save certain values for the temporary overrides below. */
+ unsigned int calculations_use_input_precision =
+ pm->calculations_use_input_precision;
+# ifdef PNG_READ_BACKGROUND_SUPPORTED
+ double maxout8 = pm->maxout8;
+# endif
+
+ /* First some arbitrary no-transform tests: */
+ if (!pm->this.speed && pm->test_gamma_threshold)
+ {
+ perform_gamma_threshold_tests(pm);
+
+ if (fail(pm))
+ return;
+ }
+
+ /* Now some real transforms. */
+ if (pm->test_gamma_transform)
+ {
+ if (summary)
+ {
+ fflush(stderr);
+ printf("Gamma correction error summary\n\n");
+ printf("The printed value is the maximum error in the pixel values\n");
+ printf("calculated by the libpng gamma correction code. The error\n");
+ printf("is calculated as the difference between the output pixel\n");
+ printf("value (always an integer) and the ideal value from the\n");
+ printf("libpng specification (typically not an integer).\n\n");
+
+ printf("Expect this value to be less than .5 for 8 bit formats,\n");
+ printf("less than 1 for formats with fewer than 8 bits and a small\n");
+ printf("number (typically less than 5) for the 16 bit formats.\n");
+ printf("For performance reasons the value for 16 bit formats\n");
+ printf("increases when the image file includes an sBIT chunk.\n");
+ fflush(stdout);
+ }
+
+ init_gamma_errors(pm);
+ /*TODO: remove this. Necessary because the current libpng
+ * implementation works in 8 bits:
+ */
+ if (pm->test_gamma_expand16)
+ pm->calculations_use_input_precision = 1;
+ perform_gamma_transform_tests(pm);
+ if (!calculations_use_input_precision)
+ pm->calculations_use_input_precision = 0;
+
+ if (summary)
+ summarize_gamma_errors(pm, 0/*who*/, 1/*low bit depth*/, 1/*indexed*/);
+
+ if (fail(pm))
+ return;
+ }
+
+ /* The sbit tests produce much larger errors: */
+ if (pm->test_gamma_sbit)
+ {
+ init_gamma_errors(pm);
+ perform_gamma_sbit_tests(pm);
+
+ if (summary)
+ summarize_gamma_errors(pm, "sBIT", pm->sbitlow < 8U, 1/*indexed*/);
+
+ if (fail(pm))
+ return;
+ }
+
+#ifdef DO_16BIT /* Should be READ_16BIT_SUPPORTED */
+ if (pm->test_gamma_scale16)
+ {
+ /* The 16 to 8 bit strip operations: */
+ init_gamma_errors(pm);
+ perform_gamma_scale16_tests(pm);
+
+ if (summary)
+ {
+ fflush(stderr);
+ printf("\nGamma correction with 16 to 8 bit reduction:\n");
+ printf(" 16 bit gray: %.5f\n", pm->error_gray_16);
+ printf(" 16 bit color: %.5f\n", pm->error_color_16);
+ fflush(stdout);
+ }
+
+ if (fail(pm))
+ return;
+ }
+#endif
+
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
+ if (pm->test_gamma_background)
+ {
+ init_gamma_errors(pm);
+
+ /*TODO: remove this. Necessary because the current libpng
+ * implementation works in 8 bits:
+ */
+ if (pm->test_gamma_expand16)
+ {
+ pm->calculations_use_input_precision = 1;
+ pm->maxout8 = .499; /* because the 16 bit background is smashed */
+ }
+ perform_gamma_composition_tests(pm, PNG_BACKGROUND_GAMMA_UNIQUE,
+ pm->test_gamma_expand16);
+ if (!calculations_use_input_precision)
+ pm->calculations_use_input_precision = 0;
+ pm->maxout8 = maxout8;
+
+ if (summary)
+ summarize_gamma_errors(pm, "background", 1, 0/*indexed*/);
+
+ if (fail(pm))
+ return;
+ }
+#endif
+
+#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
+ if (pm->test_gamma_alpha_mode)
+ {
+ int do_background;
+
+ init_gamma_errors(pm);
+
+ /*TODO: remove this. Necessary because the current libpng
+ * implementation works in 8 bits:
+ */
+ if (pm->test_gamma_expand16)
+ pm->calculations_use_input_precision = 1;
+ for (do_background = ALPHA_MODE_OFFSET + PNG_ALPHA_STANDARD;
+ do_background <= ALPHA_MODE_OFFSET + PNG_ALPHA_BROKEN && !fail(pm);
+ ++do_background)
+ perform_gamma_composition_tests(pm, do_background,
+ pm->test_gamma_expand16);
+ if (!calculations_use_input_precision)
+ pm->calculations_use_input_precision = 0;
+
+ if (summary)
+ summarize_gamma_errors(pm, "alpha mode", 1, 0/*indexed*/);
+
+ if (fail(pm))
+ return;
+ }
+#endif
+}
+#endif /* PNG_READ_GAMMA_SUPPORTED */
+#endif /* PNG_READ_SUPPORTED */
+
+/* INTERLACE MACRO VALIDATION */
+/* This is copied verbatim from the specification, it is simply the pass
+ * number in which each pixel in each 8x8 tile appears. The array must
+ * be indexed adam7[y][x] and notice that the pass numbers are based at
+ * 1, not 0 - the base libpng uses.
+ */
+static const
+png_byte adam7[8][8] =
+{
+ { 1,6,4,6,2,6,4,6 },
+ { 7,7,7,7,7,7,7,7 },
+ { 5,6,5,6,5,6,5,6 },
+ { 7,7,7,7,7,7,7,7 },
+ { 3,6,4,6,3,6,4,6 },
+ { 7,7,7,7,7,7,7,7 },
+ { 5,6,5,6,5,6,5,6 },
+ { 7,7,7,7,7,7,7,7 }
+};
+
+/* This routine validates all the interlace support macros in png.h for
+ * a variety of valid PNG widths and heights. It uses a number of similarly
+ * named internal routines that feed off the above array.
+ */
+static png_uint_32
+png_pass_start_row(int pass)
+{
+ int x, y;
+ ++pass;
+ for (y=0; y<8; ++y) for (x=0; x<8; ++x) if (adam7[y][x] == pass)
+ return y;
+ return 0xf;
+}
+
+static png_uint_32
+png_pass_start_col(int pass)
+{
+ int x, y;
+ ++pass;
+ for (x=0; x<8; ++x) for (y=0; y<8; ++y) if (adam7[y][x] == pass)
+ return x;
+ return 0xf;
+}
+
+static int
+png_pass_row_shift(int pass)
+{
+ int x, y, base=(-1), inc=8;
+ ++pass;
+ for (y=0; y<8; ++y) for (x=0; x<8; ++x) if (adam7[y][x] == pass)
+ {
+ if (base == (-1))
+ base = y;
+ else if (base == y)
+ {}
+ else if (inc == y-base)
+ base=y;
+ else if (inc == 8)
+ inc = y-base, base=y;
+ else if (inc != y-base)
+ return 0xff; /* error - more than one 'inc' value! */
+ }
+
+ if (base == (-1)) return 0xfe; /* error - no row in pass! */
+
+ /* The shift is always 1, 2 or 3 - no pass has all the rows! */
+ switch (inc)
+ {
+case 2: return 1;
+case 4: return 2;
+case 8: return 3;
+default: break;
+ }
+
+ /* error - unrecognized 'inc' */
+ return (inc << 8) + 0xfd;
+}
+
+static int
+png_pass_col_shift(int pass)
+{
+ int x, y, base=(-1), inc=8;
+ ++pass;
+ for (x=0; x<8; ++x) for (y=0; y<8; ++y) if (adam7[y][x] == pass)
+ {
+ if (base == (-1))
+ base = x;
+ else if (base == x)
+ {}
+ else if (inc == x-base)
+ base=x;
+ else if (inc == 8)
+ inc = x-base, base=x;
+ else if (inc != x-base)
+ return 0xff; /* error - more than one 'inc' value! */
+ }
+
+ if (base == (-1)) return 0xfe; /* error - no row in pass! */
+
+ /* The shift is always 1, 2 or 3 - no pass has all the rows! */
+ switch (inc)
+ {
+case 1: return 0; /* pass 7 has all the columns */
+case 2: return 1;
+case 4: return 2;
+case 8: return 3;
+default: break;
+ }
+
+ /* error - unrecognized 'inc' */
+ return (inc << 8) + 0xfd;
+}
+
+static png_uint_32
+png_row_from_pass_row(png_uint_32 yIn, int pass)
+{
+ /* By examination of the array: */
+ switch (pass)
+ {
+case 0: return yIn * 8;
+case 1: return yIn * 8;
+case 2: return yIn * 8 + 4;
+case 3: return yIn * 4;
+case 4: return yIn * 4 + 2;
+case 5: return yIn * 2;
+case 6: return yIn * 2 + 1;
+default: break;
+ }
+
+ return 0xff; /* bad pass number */
+}
+
+static png_uint_32
+png_col_from_pass_col(png_uint_32 xIn, int pass)
+{
+ /* By examination of the array: */
+ switch (pass)
+ {
+case 0: return xIn * 8;
+case 1: return xIn * 8 + 4;
+case 2: return xIn * 4;
+case 3: return xIn * 4 + 2;
+case 4: return xIn * 2;
+case 5: return xIn * 2 + 1;
+case 6: return xIn;
+default: break;
+ }
+
+ return 0xff; /* bad pass number */
+}
+
+static int
+png_row_in_interlace_pass(png_uint_32 y, int pass)
+{
+ /* Is row 'y' in pass 'pass'? */
+ int x;
+ y &= 7;
+ ++pass;
+ for (x=0; x<8; ++x) if (adam7[y][x] == pass)
+ return 1;
+
+ return 0;
+}
+
+static int
+png_col_in_interlace_pass(png_uint_32 x, int pass)
+{
+ /* Is column 'x' in pass 'pass'? */
+ int y;
+ x &= 7;
+ ++pass;
+ for (y=0; y<8; ++y) if (adam7[y][x] == pass)
+ return 1;
+
+ return 0;
+}
+
+static png_uint_32
+png_pass_rows(png_uint_32 height, int pass)
+{
+ png_uint_32 tiles = height>>3;
+ png_uint_32 rows = 0;
+ unsigned int x, y;
+
+ height &= 7;
+ ++pass;
+ for (y=0; y<8; ++y) for (x=0; x<8; ++x) if (adam7[y][x] == pass)
+ {
+ rows += tiles;
+ if (y < height) ++rows;
+ break; /* i.e. break the 'x', column, loop. */
+ }
+
+ return rows;
+}
+
+static png_uint_32
+png_pass_cols(png_uint_32 width, int pass)
+{
+ png_uint_32 tiles = width>>3;
+ png_uint_32 cols = 0;
+ unsigned int x, y;
+
+ width &= 7;
+ ++pass;
+ for (x=0; x<8; ++x) for (y=0; y<8; ++y) if (adam7[y][x] == pass)
+ {
+ cols += tiles;
+ if (x < width) ++cols;
+ break; /* i.e. break the 'y', row, loop. */
+ }
+
+ return cols;
+}
+
+static void
+perform_interlace_macro_validation(void)
+{
+ /* The macros to validate, first those that depend only on pass:
+ *
+ * PNG_PASS_START_ROW(pass)
+ * PNG_PASS_START_COL(pass)
+ * PNG_PASS_ROW_SHIFT(pass)
+ * PNG_PASS_COL_SHIFT(pass)
+ */
+ int pass;
+
+ for (pass=0; pass<7; ++pass)
+ {
+ png_uint_32 m, f, v;
+
+ m = PNG_PASS_START_ROW(pass);
+ f = png_pass_start_row(pass);
+ if (m != f)
+ {
+ fprintf(stderr, "PNG_PASS_START_ROW(%d) = %u != %x\n", pass, m, f);
+ exit(99);
+ }
+
+ m = PNG_PASS_START_COL(pass);
+ f = png_pass_start_col(pass);
+ if (m != f)
+ {
+ fprintf(stderr, "PNG_PASS_START_COL(%d) = %u != %x\n", pass, m, f);
+ exit(99);
+ }
+
+ m = PNG_PASS_ROW_SHIFT(pass);
+ f = png_pass_row_shift(pass);
+ if (m != f)
+ {
+ fprintf(stderr, "PNG_PASS_ROW_SHIFT(%d) = %u != %x\n", pass, m, f);
+ exit(99);
+ }
+
+ m = PNG_PASS_COL_SHIFT(pass);
+ f = png_pass_col_shift(pass);
+ if (m != f)
+ {
+ fprintf(stderr, "PNG_PASS_COL_SHIFT(%d) = %u != %x\n", pass, m, f);
+ exit(99);
+ }
+
+ /* Macros that depend on the image or sub-image height too:
+ *
+ * PNG_PASS_ROWS(height, pass)
+ * PNG_PASS_COLS(width, pass)
+ * PNG_ROW_FROM_PASS_ROW(yIn, pass)
+ * PNG_COL_FROM_PASS_COL(xIn, pass)
+ * PNG_ROW_IN_INTERLACE_PASS(y, pass)
+ * PNG_COL_IN_INTERLACE_PASS(x, pass)
+ */
+ for (v=0;;)
+ {
+ /* First the base 0 stuff: */
+ m = PNG_ROW_FROM_PASS_ROW(v, pass);
+ f = png_row_from_pass_row(v, pass);
+ if (m != f)
+ {
+ fprintf(stderr, "PNG_ROW_FROM_PASS_ROW(%u, %d) = %u != %x\n",
+ v, pass, m, f);
+ exit(99);
+ }
+
+ m = PNG_COL_FROM_PASS_COL(v, pass);
+ f = png_col_from_pass_col(v, pass);
+ if (m != f)
+ {
+ fprintf(stderr, "PNG_COL_FROM_PASS_COL(%u, %d) = %u != %x\n",
+ v, pass, m, f);
+ exit(99);
+ }
+
+ m = PNG_ROW_IN_INTERLACE_PASS(v, pass);
+ f = png_row_in_interlace_pass(v, pass);
+ if (m != f)
+ {
+ fprintf(stderr, "PNG_ROW_IN_INTERLACE_PASS(%u, %d) = %u != %x\n",
+ v, pass, m, f);
+ exit(99);
+ }
+
+ m = PNG_COL_IN_INTERLACE_PASS(v, pass);
+ f = png_col_in_interlace_pass(v, pass);
+ if (m != f)
+ {
+ fprintf(stderr, "PNG_COL_IN_INTERLACE_PASS(%u, %d) = %u != %x\n",
+ v, pass, m, f);
+ exit(99);
+ }
+
+ /* Then the base 1 stuff: */
+ ++v;
+ m = PNG_PASS_ROWS(v, pass);
+ f = png_pass_rows(v, pass);
+ if (m != f)
+ {
+ fprintf(stderr, "PNG_PASS_ROWS(%u, %d) = %u != %x\n",
+ v, pass, m, f);
+ exit(99);
+ }
+
+ m = PNG_PASS_COLS(v, pass);
+ f = png_pass_cols(v, pass);
+ if (m != f)
+ {
+ fprintf(stderr, "PNG_PASS_COLS(%u, %d) = %u != %x\n",
+ v, pass, m, f);
+ exit(99);
+ }
+
+ /* Move to the next v - the stepping algorithm starts skipping
+ * values above 1024.
+ */
+ if (v > 1024)
+ {
+ if (v == PNG_UINT_31_MAX)
+ break;
+
+ v = (v << 1) ^ v;
+ if (v >= PNG_UINT_31_MAX)
+ v = PNG_UINT_31_MAX-1;
+ }
+ }
+ }
+}
+
+/* Test color encodings. These values are back-calculated from the published
+ * chromaticities. The values are accurate to about 14 decimal places; 15 are
+ * given. These values are much more accurate than the ones given in the spec,
+ * which typically don't exceed 4 decimal places. This allows testing of the
+ * libpng code to its theoretical accuracy of 4 decimal places. (If pngvalid
+ * used the published errors the 'slack' permitted would have to be +/-.5E-4 or
+ * more.)
+ *
+ * The png_modifier code assumes that encodings[0] is sRGB and treats it
+ * specially: do not change the first entry in this list!
+ */
+static const color_encoding test_encodings[] =
+{
+/* sRGB: must be first in this list! */
+/*gamma:*/ { 1/2.2,
+/*red: */ { 0.412390799265959, 0.212639005871510, 0.019330818715592 },
+/*green:*/ { 0.357584339383878, 0.715168678767756, 0.119194779794626 },
+/*blue: */ { 0.180480788401834, 0.072192315360734, 0.950532152249660} },
+/* Kodak ProPhoto (wide gamut) */
+/*gamma:*/ { 1/1.6 /*approximate: uses 1.8 power law compared to sRGB 2.4*/,
+/*red: */ { 0.797760489672303, 0.288071128229293, 0.000000000000000 },
+/*green:*/ { 0.135185837175740, 0.711843217810102, 0.000000000000000 },
+/*blue: */ { 0.031349349581525, 0.000085653960605, 0.825104602510460} },
+/* Adobe RGB (1998) */
+/*gamma:*/ { 1/(2+51./256),
+/*red: */ { 0.576669042910131, 0.297344975250536, 0.027031361386412 },
+/*green:*/ { 0.185558237906546, 0.627363566255466, 0.070688852535827 },
+/*blue: */ { 0.188228646234995, 0.075291458493998, 0.991337536837639} },
+/* Adobe Wide Gamut RGB */
+/*gamma:*/ { 1/(2+51./256),
+/*red: */ { 0.716500716779386, 0.258728243040113, 0.000000000000000 },
+/*green:*/ { 0.101020574397477, 0.724682314948566, 0.051211818965388 },
+/*blue: */ { 0.146774385252705, 0.016589442011321, 0.773892783545073} },
+/* Fake encoding which selects just the green channel */
+/*gamma:*/ { 1.45/2.2, /* the 'Mac' gamma */
+/*red: */ { 0.716500716779386, 0.000000000000000, 0.000000000000000 },
+/*green:*/ { 0.101020574397477, 1.000000000000000, 0.051211818965388 },
+/*blue: */ { 0.146774385252705, 0.000000000000000, 0.773892783545073} },
+};
+
+/* signal handler
+ *
+ * This attempts to trap signals and escape without crashing. It needs a
+ * context pointer so that it can throw an exception (call longjmp) to recover
+ * from the condition; this is handled by making the png_modifier used by 'main'
+ * into a global variable.
+ */
+static png_modifier pm;
+
+static void signal_handler(int signum)
+{
+
+ size_t pos = 0;
+ char msg[64];
+
+ pos = safecat(msg, sizeof msg, pos, "caught signal: ");
+
+ switch (signum)
+ {
+ case SIGABRT:
+ pos = safecat(msg, sizeof msg, pos, "abort");
+ break;
+
+ case SIGFPE:
+ pos = safecat(msg, sizeof msg, pos, "floating point exception");
+ break;
+
+ case SIGILL:
+ pos = safecat(msg, sizeof msg, pos, "illegal instruction");
+ break;
+
+ case SIGINT:
+ pos = safecat(msg, sizeof msg, pos, "interrupt");
+ break;
+
+ case SIGSEGV:
+ pos = safecat(msg, sizeof msg, pos, "invalid memory access");
+ break;
+
+ case SIGTERM:
+ pos = safecat(msg, sizeof msg, pos, "termination request");
+ break;
+
+ default:
+ pos = safecat(msg, sizeof msg, pos, "unknown ");
+ pos = safecatn(msg, sizeof msg, pos, signum);
+ break;
+ }
+
+ store_log(&pm.this, NULL/*png_structp*/, msg, 1/*error*/);
+
+ /* And finally throw an exception so we can keep going, unless this is
+ * SIGTERM in which case stop now.
+ */
+ if (signum != SIGTERM)
+ {
+ struct exception_context *the_exception_context =
+ &pm.this.exception_context;
+
+ Throw &pm.this;
+ }
+
+ else
+ exit(1);
+}
+
+/* main program */
+int main(int argc, char **argv)
+{
+ int summary = 1; /* Print the error summary at the end */
+ int memstats = 0; /* Print memory statistics at the end */
+
+ /* Create the given output file on success: */
+ const char *touch = NULL;
+
+ /* This is an array of standard gamma values (believe it or not I've seen
+ * every one of these mentioned somewhere.)
+ *
+ * In the following list the most useful values are first!
+ */
+ static double
+ gammas[]={2.2, 1.0, 2.2/1.45, 1.8, 1.5, 2.4, 2.5, 2.62, 2.9};
+
+ /* This records the command and arguments: */
+ size_t cp = 0;
+ char command[1024];
+
+ anon_context(&pm.this);
+
+ gnu_volatile(summary)
+ gnu_volatile(memstats)
+ gnu_volatile(touch)
+
+ /* Add appropriate signal handlers, just the ANSI specified ones: */
+ signal(SIGABRT, signal_handler);
+ signal(SIGFPE, signal_handler);
+ signal(SIGILL, signal_handler);
+ signal(SIGINT, signal_handler);
+ signal(SIGSEGV, signal_handler);
+ signal(SIGTERM, signal_handler);
+
+#ifdef HAVE_FEENABLEEXCEPT
+ /* Only required to enable FP exceptions on platforms where they start off
+ * disabled; this is not necessary but if it is not done pngvalid will likely
+ * end up ignoring FP conditions that other platforms fault.
+ */
+ feenableexcept(FE_DIVBYZERO | FE_INVALID | FE_OVERFLOW);
+#endif
+
+ modifier_init(&pm);
+
+ /* Preallocate the image buffer, because we know how big it needs to be,
+ * note that, for testing purposes, it is deliberately mis-aligned by tag
+ * bytes either side. All rows have an additional five bytes of padding for
+ * overwrite checking.
+ */
+ store_ensure_image(&pm.this, NULL, 2, TRANSFORM_ROWMAX, TRANSFORM_HEIGHTMAX);
+
+ /* Don't give argv[0], it's normally some horrible libtool string: */
+ cp = safecat(command, sizeof command, cp, "pngvalid");
+
+ /* Default to error on warning: */
+ pm.this.treat_warnings_as_errors = 1;
+
+ /* Default assume_16_bit_calculations appropriately; this tells the checking
+ * code that 16-bit arithmetic is used for 8-bit samples when it would make a
+ * difference.
+ */
+ pm.assume_16_bit_calculations = PNG_LIBPNG_VER >= 10700;
+
+ /* Currently 16 bit expansion happens at the end of the pipeline, so the
+ * calculations are done in the input bit depth not the output.
+ *
+ * TODO: fix this
+ */
+ pm.calculations_use_input_precision = 1U;
+
+ /* Store the test gammas */
+ pm.gammas = gammas;
+ pm.ngammas = ARRAY_SIZE(gammas);
+ pm.ngamma_tests = 0; /* default to off */
+
+ /* Low bit depth gray images don't do well in the gamma tests, until
+ * this is fixed turn them off for some gamma cases:
+ */
+# ifdef PNG_WRITE_tRNS_SUPPORTED
+ pm.test_tRNS = 1;
+# endif
+ pm.test_lbg = PNG_LIBPNG_VER >= 10600;
+ pm.test_lbg_gamma_threshold = 1;
+ pm.test_lbg_gamma_transform = PNG_LIBPNG_VER >= 10600;
+ pm.test_lbg_gamma_sbit = 1;
+ pm.test_lbg_gamma_composition = PNG_LIBPNG_VER >= 10700;
+
+ /* And the test encodings */
+ pm.encodings = test_encodings;
+ pm.nencodings = ARRAY_SIZE(test_encodings);
+
+# if PNG_LIBPNG_VER < 10700
+ pm.sbitlow = 8U; /* because libpng doesn't do sBIT below 8! */
+# else
+ pm.sbitlow = 1U;
+# endif
+
+ /* The following allows results to pass if they correspond to anything in the
+ * transformed range [input-.5,input+.5]; this is is required because of the
+ * way libpng treates the 16_TO_8 flag when building the gamma tables in
+ * releases up to 1.6.0.
+ *
+ * TODO: review this
+ */
+ pm.use_input_precision_16to8 = 1U;
+ pm.use_input_precision_sbit = 1U; /* because libpng now rounds sBIT */
+
+ /* Some default values (set the behavior for 'make check' here).
+ * These values simply control the maximum error permitted in the gamma
+ * transformations. The practial limits for human perception are described
+ * below (the setting for maxpc16), however for 8 bit encodings it isn't
+ * possible to meet the accepted capabilities of human vision - i.e. 8 bit
+ * images can never be good enough, regardless of encoding.
+ */
+ pm.maxout8 = .1; /* Arithmetic error in *encoded* value */
+ pm.maxabs8 = .00005; /* 1/20000 */
+ pm.maxcalc8 = 1./255; /* +/-1 in 8 bits for compose errors */
+ pm.maxpc8 = .499; /* I.e., .499% fractional error */
+ pm.maxout16 = .499; /* Error in *encoded* value */
+ pm.maxabs16 = .00005;/* 1/20000 */
+ pm.maxcalc16 =1./65535;/* +/-1 in 16 bits for compose errors */
+# if PNG_LIBPNG_VER < 10700
+ pm.maxcalcG = 1./((1<<PNG_MAX_GAMMA_8)-1);
+# else
+ pm.maxcalcG = 1./((1<<16)-1);
+# endif
+
+ /* NOTE: this is a reasonable perceptual limit. We assume that humans can
+ * perceive light level differences of 1% over a 100:1 range, so we need to
+ * maintain 1 in 10000 accuracy (in linear light space), which is what the
+ * following guarantees. It also allows significantly higher errors at
+ * higher 16 bit values, which is important for performance. The actual
+ * maximum 16 bit error is about +/-1.9 in the fixed point implementation but
+ * this is only allowed for values >38149 by the following:
+ */
+ pm.maxpc16 = .005; /* I.e., 1/200% - 1/20000 */
+
+ /* Now parse the command line options. */
+ while (--argc >= 1)
+ {
+ int catmore = 0; /* Set if the argument has an argument. */
+
+ /* Record each argument for posterity: */
+ cp = safecat(command, sizeof command, cp, " ");
+ cp = safecat(command, sizeof command, cp, *++argv);
+
+ if (strcmp(*argv, "-v") == 0)
+ pm.this.verbose = 1;
+
+ else if (strcmp(*argv, "-l") == 0)
+ pm.log = 1;
+
+ else if (strcmp(*argv, "-q") == 0)
+ summary = pm.this.verbose = pm.log = 0;
+
+ else if (strcmp(*argv, "-w") == 0 ||
+ strcmp(*argv, "--strict") == 0)
+ pm.this.treat_warnings_as_errors = 0;
+
+ else if (strcmp(*argv, "--speed") == 0)
+ pm.this.speed = 1, pm.ngamma_tests = pm.ngammas, pm.test_standard = 0,
+ summary = 0;
+
+ else if (strcmp(*argv, "--memory") == 0)
+ memstats = 1;
+
+ else if (strcmp(*argv, "--size") == 0)
+ pm.test_size = 1;
+
+ else if (strcmp(*argv, "--nosize") == 0)
+ pm.test_size = 0;
+
+ else if (strcmp(*argv, "--standard") == 0)
+ pm.test_standard = 1;
+
+ else if (strcmp(*argv, "--nostandard") == 0)
+ pm.test_standard = 0;
+
+ else if (strcmp(*argv, "--transform") == 0)
+ pm.test_transform = 1;
+
+ else if (strcmp(*argv, "--notransform") == 0)
+ pm.test_transform = 0;
+
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
+ else if (strncmp(*argv, "--transform-disable=",
+ sizeof "--transform-disable") == 0)
+ {
+ pm.test_transform = 1;
+ transform_disable(*argv + sizeof "--transform-disable");
+ }
+
+ else if (strncmp(*argv, "--transform-enable=",
+ sizeof "--transform-enable") == 0)
+ {
+ pm.test_transform = 1;
+ transform_enable(*argv + sizeof "--transform-enable");
+ }
+#endif /* PNG_READ_TRANSFORMS_SUPPORTED */
+
+ else if (strcmp(*argv, "--gamma") == 0)
+ {
+ /* Just do two gamma tests here (2.2 and linear) for speed: */
+ pm.ngamma_tests = 2U;
+ pm.test_gamma_threshold = 1;
+ pm.test_gamma_transform = 1;
+ pm.test_gamma_sbit = 1;
+ pm.test_gamma_scale16 = 1;
+ pm.test_gamma_background = 1; /* composition */
+ pm.test_gamma_alpha_mode = 1;
+ }
+
+ else if (strcmp(*argv, "--nogamma") == 0)
+ pm.ngamma_tests = 0;
+
+ else if (strcmp(*argv, "--gamma-threshold") == 0)
+ pm.ngamma_tests = 2U, pm.test_gamma_threshold = 1;
+
+ else if (strcmp(*argv, "--nogamma-threshold") == 0)
+ pm.test_gamma_threshold = 0;
+
+ else if (strcmp(*argv, "--gamma-transform") == 0)
+ pm.ngamma_tests = 2U, pm.test_gamma_transform = 1;
+
+ else if (strcmp(*argv, "--nogamma-transform") == 0)
+ pm.test_gamma_transform = 0;
+
+ else if (strcmp(*argv, "--gamma-sbit") == 0)
+ pm.ngamma_tests = 2U, pm.test_gamma_sbit = 1;
+
+ else if (strcmp(*argv, "--nogamma-sbit") == 0)
+ pm.test_gamma_sbit = 0;
+
+ else if (strcmp(*argv, "--gamma-16-to-8") == 0)
+ pm.ngamma_tests = 2U, pm.test_gamma_scale16 = 1;
+
+ else if (strcmp(*argv, "--nogamma-16-to-8") == 0)
+ pm.test_gamma_scale16 = 0;
+
+ else if (strcmp(*argv, "--gamma-background") == 0)
+ pm.ngamma_tests = 2U, pm.test_gamma_background = 1;
+
+ else if (strcmp(*argv, "--nogamma-background") == 0)
+ pm.test_gamma_background = 0;
+
+ else if (strcmp(*argv, "--gamma-alpha-mode") == 0)
+ pm.ngamma_tests = 2U, pm.test_gamma_alpha_mode = 1;
+
+ else if (strcmp(*argv, "--nogamma-alpha-mode") == 0)
+ pm.test_gamma_alpha_mode = 0;
+
+ else if (strcmp(*argv, "--expand16") == 0)
+ pm.test_gamma_expand16 = 1;
+
+ else if (strcmp(*argv, "--noexpand16") == 0)
+ pm.test_gamma_expand16 = 0;
+
+ else if (strcmp(*argv, "--low-depth-gray") == 0)
+ pm.test_lbg = pm.test_lbg_gamma_threshold =
+ pm.test_lbg_gamma_transform = pm.test_lbg_gamma_sbit =
+ pm.test_lbg_gamma_composition = 1;
+
+ else if (strcmp(*argv, "--nolow-depth-gray") == 0)
+ pm.test_lbg = pm.test_lbg_gamma_threshold =
+ pm.test_lbg_gamma_transform = pm.test_lbg_gamma_sbit =
+ pm.test_lbg_gamma_composition = 0;
+
+# ifdef PNG_WRITE_tRNS_SUPPORTED
+ else if (strcmp(*argv, "--tRNS") == 0)
+ pm.test_tRNS = 1;
+# endif
+
+ else if (strcmp(*argv, "--notRNS") == 0)
+ pm.test_tRNS = 0;
+
+ else if (strcmp(*argv, "--more-gammas") == 0)
+ pm.ngamma_tests = 3U;
+
+ else if (strcmp(*argv, "--all-gammas") == 0)
+ pm.ngamma_tests = pm.ngammas;
+
+ else if (strcmp(*argv, "--progressive-read") == 0)
+ pm.this.progressive = 1;
+
+ else if (strcmp(*argv, "--use-update-info") == 0)
+ ++pm.use_update_info; /* Can call multiple times */
+
+ else if (strcmp(*argv, "--interlace") == 0)
+ {
+# if CAN_WRITE_INTERLACE
+ pm.interlace_type = PNG_INTERLACE_ADAM7;
+# else /* !CAN_WRITE_INTERLACE */
+ fprintf(stderr, "pngvalid: no write interlace support\n");
+ return SKIP;
+# endif /* !CAN_WRITE_INTERLACE */
+ }
+
+ else if (strcmp(*argv, "--use-input-precision") == 0)
+ pm.use_input_precision = 1U;
+
+ else if (strcmp(*argv, "--use-calculation-precision") == 0)
+ pm.use_input_precision = 0;
+
+ else if (strcmp(*argv, "--calculations-use-input-precision") == 0)
+ pm.calculations_use_input_precision = 1U;
+
+ else if (strcmp(*argv, "--assume-16-bit-calculations") == 0)
+ pm.assume_16_bit_calculations = 1U;
+
+ else if (strcmp(*argv, "--calculations-follow-bit-depth") == 0)
+ pm.calculations_use_input_precision =
+ pm.assume_16_bit_calculations = 0;
+
+ else if (strcmp(*argv, "--exhaustive") == 0)
+ pm.test_exhaustive = 1;
+
+ else if (argc > 1 && strcmp(*argv, "--sbitlow") == 0)
+ --argc, pm.sbitlow = (png_byte)atoi(*++argv), catmore = 1;
+
+ else if (argc > 1 && strcmp(*argv, "--touch") == 0)
+ --argc, touch = *++argv, catmore = 1;
+
+ else if (argc > 1 && strncmp(*argv, "--max", 5) == 0)
+ {
+ --argc;
+
+ if (strcmp(5+*argv, "abs8") == 0)
+ pm.maxabs8 = atof(*++argv);
+
+ else if (strcmp(5+*argv, "abs16") == 0)
+ pm.maxabs16 = atof(*++argv);
+
+ else if (strcmp(5+*argv, "calc8") == 0)
+ pm.maxcalc8 = atof(*++argv);
+
+ else if (strcmp(5+*argv, "calc16") == 0)
+ pm.maxcalc16 = atof(*++argv);
+
+ else if (strcmp(5+*argv, "out8") == 0)
+ pm.maxout8 = atof(*++argv);
+
+ else if (strcmp(5+*argv, "out16") == 0)
+ pm.maxout16 = atof(*++argv);
+
+ else if (strcmp(5+*argv, "pc8") == 0)
+ pm.maxpc8 = atof(*++argv);
+
+ else if (strcmp(5+*argv, "pc16") == 0)
+ pm.maxpc16 = atof(*++argv);
+
+ else
+ {
+ fprintf(stderr, "pngvalid: %s: unknown 'max' option\n", *argv);
+ exit(99);
+ }
+
+ catmore = 1;
+ }
+
+ else if (strcmp(*argv, "--log8") == 0)
+ --argc, pm.log8 = atof(*++argv), catmore = 1;
+
+ else if (strcmp(*argv, "--log16") == 0)
+ --argc, pm.log16 = atof(*++argv), catmore = 1;
+
+#ifdef PNG_SET_OPTION_SUPPORTED
+ else if (strncmp(*argv, "--option=", 9) == 0)
+ {
+ /* Syntax of the argument is <option>:{on|off} */
+ const char *arg = 9+*argv;
+ unsigned char option=0, setting=0;
+
+#ifdef PNG_ARM_NEON
+ if (strncmp(arg, "arm-neon:", 9) == 0)
+ option = PNG_ARM_NEON, arg += 9;
+
+ else
+#endif
+#ifdef PNG_EXTENSIONS
+ if (strncmp(arg, "extensions:", 11) == 0)
+ option = PNG_EXTENSIONS, arg += 11;
+
+ else
+#endif
+#ifdef PNG_MAXIMUM_INFLATE_WINDOW
+ if (strncmp(arg, "max-inflate-window:", 19) == 0)
+ option = PNG_MAXIMUM_INFLATE_WINDOW, arg += 19;
+
+ else
+#endif
+ {
+ fprintf(stderr, "pngvalid: %s: %s: unknown option\n", *argv, arg);
+ exit(99);
+ }
+
+ if (strcmp(arg, "off") == 0)
+ setting = PNG_OPTION_OFF;
+
+ else if (strcmp(arg, "on") == 0)
+ setting = PNG_OPTION_ON;
+
+ else
+ {
+ fprintf(stderr,
+ "pngvalid: %s: %s: unknown setting (use 'on' or 'off')\n",
+ *argv, arg);
+ exit(99);
+ }
+
+ pm.this.options[pm.this.noptions].option = option;
+ pm.this.options[pm.this.noptions++].setting = setting;
+ }
+#endif /* PNG_SET_OPTION_SUPPORTED */
+
+ else
+ {
+ fprintf(stderr, "pngvalid: %s: unknown argument\n", *argv);
+ exit(99);
+ }
+
+ if (catmore) /* consumed an extra *argv */
+ {
+ cp = safecat(command, sizeof command, cp, " ");
+ cp = safecat(command, sizeof command, cp, *argv);
+ }
+ }
+
+ /* If pngvalid is run with no arguments default to a reasonable set of the
+ * tests.
+ */
+ if (pm.test_standard == 0 && pm.test_size == 0 && pm.test_transform == 0 &&
+ pm.ngamma_tests == 0)
+ {
+ /* Make this do all the tests done in the test shell scripts with the same
+ * parameters, where possible. The limitation is that all the progressive
+ * read and interlace stuff has to be done in separate runs, so only the
+ * basic 'standard' and 'size' tests are done.
+ */
+ pm.test_standard = 1;
+ pm.test_size = 1;
+ pm.test_transform = 1;
+ pm.ngamma_tests = 2U;
+ }
+
+ if (pm.ngamma_tests > 0 &&
+ pm.test_gamma_threshold == 0 && pm.test_gamma_transform == 0 &&
+ pm.test_gamma_sbit == 0 && pm.test_gamma_scale16 == 0 &&
+ pm.test_gamma_background == 0 && pm.test_gamma_alpha_mode == 0)
+ {
+ pm.test_gamma_threshold = 1;
+ pm.test_gamma_transform = 1;
+ pm.test_gamma_sbit = 1;
+ pm.test_gamma_scale16 = 1;
+ pm.test_gamma_background = 1;
+ pm.test_gamma_alpha_mode = 1;
+ }
+
+ else if (pm.ngamma_tests == 0)
+ {
+ /* Nothing to test so turn everything off: */
+ pm.test_gamma_threshold = 0;
+ pm.test_gamma_transform = 0;
+ pm.test_gamma_sbit = 0;
+ pm.test_gamma_scale16 = 0;
+ pm.test_gamma_background = 0;
+ pm.test_gamma_alpha_mode = 0;
+ }
+
+ Try
+ {
+ /* Make useful base images */
+ make_transform_images(&pm);
+
+ /* Perform the standard and gamma tests. */
+ if (pm.test_standard)
+ {
+ perform_interlace_macro_validation();
+ perform_formatting_test(&pm.this);
+# ifdef PNG_READ_SUPPORTED
+ perform_standard_test(&pm);
+# endif
+ perform_error_test(&pm);
+ }
+
+ /* Various oddly sized images: */
+ if (pm.test_size)
+ {
+ make_size_images(&pm.this);
+# ifdef PNG_READ_SUPPORTED
+ perform_size_test(&pm);
+# endif
+ }
+
+#ifdef PNG_READ_TRANSFORMS_SUPPORTED
+ /* Combinatorial transforms: */
+ if (pm.test_transform)
+ perform_transform_test(&pm);
+#endif /* PNG_READ_TRANSFORMS_SUPPORTED */
+
+#ifdef PNG_READ_GAMMA_SUPPORTED
+ if (pm.ngamma_tests > 0)
+ perform_gamma_test(&pm, summary);
+#endif
+ }
+
+ Catch_anonymous
+ {
+ fprintf(stderr, "pngvalid: test aborted (probably failed in cleanup)\n");
+ if (!pm.this.verbose)
+ {
+ if (pm.this.error[0] != 0)
+ fprintf(stderr, "pngvalid: first error: %s\n", pm.this.error);
+
+ fprintf(stderr, "pngvalid: run with -v to see what happened\n");
+ }
+ exit(1);
+ }
+
+ if (summary)
+ {
+ printf("%s: %s (%s point arithmetic)\n",
+ (pm.this.nerrors || (pm.this.treat_warnings_as_errors &&
+ pm.this.nwarnings)) ? "FAIL" : "PASS",
+ command,
+#if defined(PNG_FLOATING_ARITHMETIC_SUPPORTED) || PNG_LIBPNG_VER < 10500
+ "floating"
+#else
+ "fixed"
+#endif
+ );
+ }
+
+ if (memstats)
+ {
+ printf("Allocated memory statistics (in bytes):\n"
+ "\tread %lu maximum single, %lu peak, %lu total\n"
+ "\twrite %lu maximum single, %lu peak, %lu total\n",
+ (unsigned long)pm.this.read_memory_pool.max_max,
+ (unsigned long)pm.this.read_memory_pool.max_limit,
+ (unsigned long)pm.this.read_memory_pool.max_total,
+ (unsigned long)pm.this.write_memory_pool.max_max,
+ (unsigned long)pm.this.write_memory_pool.max_limit,
+ (unsigned long)pm.this.write_memory_pool.max_total);
+ }
+
+ /* Do this here to provoke memory corruption errors in memory not directly
+ * allocated by libpng - not a complete test, but better than nothing.
+ */
+ store_delete(&pm.this);
+
+ /* Error exit if there are any errors, and maybe if there are any
+ * warnings.
+ */
+ if (pm.this.nerrors || (pm.this.treat_warnings_as_errors &&
+ pm.this.nwarnings))
+ {
+ if (!pm.this.verbose)
+ fprintf(stderr, "pngvalid: %s\n", pm.this.error);
+
+ fprintf(stderr, "pngvalid: %d errors, %d warnings\n", pm.this.nerrors,
+ pm.this.nwarnings);
+
+ exit(1);
+ }
+
+ /* Success case. */
+ if (touch != NULL)
+ {
+ FILE *fsuccess = fopen(touch, "wt");
+
+ if (fsuccess != NULL)
+ {
+ int error = 0;
+ fprintf(fsuccess, "PNG validation succeeded\n");
+ fflush(fsuccess);
+ error = ferror(fsuccess);
+
+ if (fclose(fsuccess) || error)
+ {
+ fprintf(stderr, "%s: write failed\n", touch);
+ exit(1);
+ }
+ }
+
+ else
+ {
+ fprintf(stderr, "%s: open failed\n", touch);
+ exit(1);
+ }
+ }
+
+ /* This is required because some very minimal configurations do not use it:
+ */
+ UNUSED(fail)
+ return 0;
+}
+#else /* write or low level APIs not supported */
+int main(void)
+{
+ fprintf(stderr,
+ "pngvalid: no low level write support in libpng, all tests skipped\n");
+ /* So the test is skipped: */
+ return SKIP;
+}
+#endif
diff --git a/libpng/contrib/libtests/readpng.c b/libpng/contrib/libtests/readpng.c
new file mode 100644
index 0000000..3336d4e
--- /dev/null
+++ b/libpng/contrib/libtests/readpng.c
@@ -0,0 +1,115 @@
+/* readpng.c
+ *
+ * Copyright (c) 2013 John Cunningham Bowler
+ *
+ * Last changed in libpng 1.6.1 [March 28, 2013]
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * Load an arbitrary number of PNG files (from the command line, or, if there
+ * are no arguments on the command line, from stdin) then run a time test by
+ * reading each file by row. The test does nothing with the read result and
+ * does no transforms. The only output is a time as a floating point number of
+ * seconds with 9 decimal digits.
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H)
+# include <config.h>
+#endif
+
+/* Define the following to use this test against your installed libpng, rather
+ * than the one being built here:
+ */
+#ifdef PNG_FREESTANDING_TESTS
+# include <png.h>
+#else
+# include "../../png.h"
+#endif
+
+static int
+read_png(FILE *fp)
+{
+ png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,0,0,0);
+ png_infop info_ptr = NULL;
+ png_bytep row = NULL, display = NULL;
+
+ if (png_ptr == NULL)
+ return 0;
+
+ if (setjmp(png_jmpbuf(png_ptr)))
+ {
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+ if (row != NULL) free(row);
+ if (display != NULL) free(display);
+ return 0;
+ }
+
+ png_init_io(png_ptr, fp);
+
+ info_ptr = png_create_info_struct(png_ptr);
+ if (info_ptr == NULL)
+ png_error(png_ptr, "OOM allocating info structure");
+
+ png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_ALWAYS, NULL, 0);
+
+ png_read_info(png_ptr, info_ptr);
+
+ {
+ png_size_t rowbytes = png_get_rowbytes(png_ptr, info_ptr);
+
+ /* Failure to initialize these is harmless */
+ row = malloc(rowbytes);
+ display = malloc(rowbytes);
+
+ if (row == NULL || display == NULL)
+ png_error(png_ptr, "OOM allocating row buffers");
+
+ {
+ png_uint_32 height = png_get_image_height(png_ptr, info_ptr);
+# ifdef PNG_READ_INTERLACING_SUPPORTED
+ int passes = png_set_interlace_handling(png_ptr);
+# else /* !READ_INTERLACING */
+ int passes = png_get_interlace_type(png_ptr, info_ptr) ==
+ PNG_INTERLACE_ADAM7 ? PNG_INTERLACE_ADAM7_PASSES : 1;
+# endif /* !READ_INTERLACING */
+ int pass;
+
+ png_start_read_image(png_ptr);
+
+ for (pass = 0; pass < passes; ++pass)
+ {
+ png_uint_32 y = height;
+
+# ifndef PNG_READ_INTERLACING_SUPPORTED
+ if (passes == PNG_INTERLACE_ADAM7_PASSES)
+ y = PNG_PASS_ROWS(y, pass);
+# endif /* READ_INTERLACING */
+
+ /* NOTE: this trashes the row each time; interlace handling won't
+ * work, but this avoids memory thrashing for speed testing.
+ */
+ while (y-- > 0)
+ png_read_row(png_ptr, row, display);
+ }
+ }
+ }
+
+ /* Make sure to read to the end of the file: */
+ png_read_end(png_ptr, info_ptr);
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+ free(row);
+ free(display);
+ return 1;
+}
+
+int
+main(void)
+{
+ /* Exit code 0 on success. */
+ return !read_png(stdin);
+}
diff --git a/libpng/contrib/libtests/tarith.c b/libpng/contrib/libtests/tarith.c
new file mode 100644
index 0000000..cb17ffa
--- /dev/null
+++ b/libpng/contrib/libtests/tarith.c
@@ -0,0 +1,999 @@
+
+/* tarith.c
+ *
+ * Copyright (c) 2011-2013 John Cunningham Bowler
+ *
+ * Last changed in libpng 1.6.0 [February 14, 2013]
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * Test internal arithmetic functions of libpng.
+ *
+ * This code must be linked against a math library (-lm), but does not require
+ * libpng or zlib to work. Because it includes the complete source of 'png.c'
+ * it tests the code with whatever compiler options are used to build it.
+ * Changing these options can substantially change the errors in the
+ * calculations that the compiler chooses!
+ */
+#define _POSIX_SOURCE 1
+#define _ISOC99_SOURCE 1
+
+/* Obtain a copy of the code to be tested (plus other things), disabling
+ * stuff that is not required.
+ */
+#include <math.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <string.h>
+#include <assert.h>
+
+#include "../../pngpriv.h"
+
+#define png_error png_warning
+
+void png_warning(png_const_structrp png_ptr, png_const_charp msg)
+{
+ fprintf(stderr, "validation: %s\n", msg);
+}
+
+#define png_fixed_error png_fixed_warning
+
+void png_fixed_warning(png_const_structrp png_ptr, png_const_charp msg)
+{
+ fprintf(stderr, "overflow in: %s\n", msg);
+}
+
+#define png_set_error_fn(pp, ep, efp, wfp) ((void)0)
+#define png_malloc(pp, s) malloc(s)
+#define png_malloc_warn(pp, s) malloc(s)
+#define png_malloc_base(pp, s) malloc(s)
+#define png_calloc(pp, s) calloc(1, (s))
+#define png_free(pp, s) free(s)
+
+#define png_safecat(b, sb, pos, str) (pos)
+#define png_format_number(start, end, format, number) (start)
+
+#define crc32(crc, pp, s) (crc)
+#define inflateReset(zs) Z_OK
+
+#define png_create_struct(type) (0)
+#define png_destroy_struct(pp) ((void)0)
+#define png_create_struct_2(type, m, mm) (0)
+#define png_destroy_struct_2(pp, f, mm) ((void)0)
+
+#undef PNG_SIMPLIFIED_READ_SUPPORTED
+#undef PNG_SIMPLIFIED_WRITE_SUPPORTED
+#undef PNG_USER_MEM_SUPPORTED
+
+#include "../../png.c"
+
+/* Validate ASCII to fp routines. */
+static int verbose = 0;
+
+int validation_ascii_to_fp(int count, int argc, char **argv)
+{
+ int showall = 0;
+ double max_error=2; /* As a percentage error-in-last-digit/.5 */
+ double max_error_abs=17; /* Used when precision is DBL_DIG */
+ double max = 0;
+ double max_abs = 0;
+ double test = 0; /* Important to test this. */
+ int precision = 5;
+ int nonfinite = 0;
+ int finite = 0;
+ int ok = 0;
+ int failcount = 0;
+ int minorarith = 0;
+
+ while (--argc > 0)
+ if (strcmp(*++argv, "-a") == 0)
+ showall = 1;
+ else if (strcmp(*argv, "-e") == 0 && argc > 0)
+ {
+ --argc;
+ max_error = atof(*++argv);
+ }
+ else if (strcmp(*argv, "-E") == 0 && argc > 0)
+ {
+ --argc;
+ max_error_abs = atof(*++argv);
+ }
+ else
+ {
+ fprintf(stderr, "unknown argument %s\n", *argv);
+ return 1;
+ }
+
+ do
+ {
+ png_size_t index;
+ int state, failed = 0;
+ char buffer[64];
+
+ if (isfinite(test))
+ ++finite;
+ else
+ ++nonfinite;
+
+ if (verbose)
+ fprintf(stderr, "%.*g %d\n", DBL_DIG, test, precision);
+
+ /* Check for overflow in the buffer by setting a marker. */
+ memset(buffer, 71, sizeof buffer);
+
+ png_ascii_from_fp(0, buffer, precision+10, test, precision);
+
+ /* Allow for a three digit exponent, this stuff will fail if
+ * the exponent is bigger than this!
+ */
+ if (buffer[precision+7] != 71)
+ {
+ fprintf(stderr, "%g[%d] -> '%s'[%lu] buffer overflow\n", test,
+ precision, buffer, (unsigned long)strlen(buffer));
+ failed = 1;
+ }
+
+ /* Following are used for the number parser below and must be
+ * initialized to zero.
+ */
+ state = 0;
+ index = 0;
+ if (!isfinite(test))
+ {
+ /* Expect 'inf' */
+ if (test >= 0 && strcmp(buffer, "inf") ||
+ test < 0 && strcmp(buffer, "-inf"))
+ {
+ fprintf(stderr, "%g[%d] -> '%s' but expected 'inf'\n", test,
+ precision, buffer);
+ failed = 1;
+ }
+ }
+ else if (!png_check_fp_number(buffer, precision+10, &state, &index) ||
+ buffer[index] != 0)
+ {
+ fprintf(stderr, "%g[%d] -> '%s' but has bad format ('%c')\n", test,
+ precision, buffer, buffer[index]);
+ failed = 1;
+ }
+ else if (PNG_FP_IS_NEGATIVE(state) && !(test < 0))
+ {
+ fprintf(stderr, "%g[%d] -> '%s' but negative value not so reported\n",
+ test, precision, buffer);
+ failed = 1;
+ assert(!PNG_FP_IS_ZERO(state));
+ assert(!PNG_FP_IS_POSITIVE(state));
+ }
+ else if (PNG_FP_IS_ZERO(state) && !(test == 0))
+ {
+ fprintf(stderr, "%g[%d] -> '%s' but zero value not so reported\n",
+ test, precision, buffer);
+ failed = 1;
+ assert(!PNG_FP_IS_NEGATIVE(state));
+ assert(!PNG_FP_IS_POSITIVE(state));
+ }
+ else if (PNG_FP_IS_POSITIVE(state) && !(test > 0))
+ {
+ fprintf(stderr, "%g[%d] -> '%s' but postive value not so reported\n",
+ test, precision, buffer);
+ failed = 1;
+ assert(!PNG_FP_IS_NEGATIVE(state));
+ assert(!PNG_FP_IS_ZERO(state));
+ }
+ else
+ {
+ /* Check the result against the original. */
+ double out = atof(buffer);
+ double change = fabs((out - test)/test);
+ double allow = .5/pow(10,
+ (precision >= DBL_DIG) ? DBL_DIG-1 : precision-1);
+
+ /* NOTE: if you hit this error case are you compiling with gcc
+ * and -O0? Try -O2 - the errors can accumulate if the FP
+ * code above is not optimized and may drift outside the .5 in
+ * DBL_DIG allowed. In any case a small number of errors may
+ * occur (very small ones - 1 or 2%) because of rounding in the
+ * calculations, either in the conversion API or in atof.
+ */
+ if (change >= allow && (isfinite(out) ||
+ fabs(test/DBL_MAX) <= 1-allow))
+ {
+ double percent = (precision >= DBL_DIG) ? max_error_abs : max_error;
+ double allowp = (change-allow)*100/allow;
+
+ if (precision >= DBL_DIG)
+ {
+ if (max_abs < allowp) max_abs = allowp;
+ }
+
+ else
+ {
+ if (max < allowp) max = allowp;
+ }
+
+ if (showall || allowp >= percent)
+ {
+ fprintf(stderr,
+ "%.*g[%d] -> '%s' -> %.*g number changed (%g > %g (%d%%))\n",
+ DBL_DIG, test, precision, buffer, DBL_DIG, out, change, allow,
+ (int)round(allowp));
+ failed = 1;
+ }
+ else
+ ++minorarith;
+ }
+ }
+
+ if (failed)
+ ++failcount;
+ else
+ ++ok;
+
+skip:
+ /* Generate a new number and precision. */
+ precision = rand();
+ if (precision & 1) test = -test;
+ precision >>= 1;
+
+ /* Generate random numbers. */
+ if (test == 0 || !isfinite(test))
+ test = precision+1;
+ else
+ {
+ /* Derive the exponent from the previous rand() value. */
+ int exponent = precision % (DBL_MAX_EXP - DBL_MIN_EXP) + DBL_MIN_EXP;
+ int tmp;
+ test = frexp(test * rand(), &tmp);
+ test = ldexp(test, exponent);
+ precision >>= 8; /* arbitrary */
+ }
+
+ /* This limits the precision to 32 digits, enough for standard
+ * IEEE implementations which have at most 15 digits.
+ */
+ precision = (precision & 0x1f) + 1;
+ }
+ while (--count);
+
+ printf("Tested %d finite values, %d non-finite, %d OK (%d failed) %d minor "
+ "arithmetic errors\n", finite, nonfinite, ok, failcount, minorarith);
+ printf(" Error with >=%d digit precision %.2f%%\n", DBL_DIG, max_abs);
+ printf(" Error with < %d digit precision %.2f%%\n", DBL_DIG, max);
+
+ return 0;
+}
+
+/* Observe that valid FP numbers have the forms listed in the PNG extensions
+ * specification:
+ *
+ * [+,-]{integer,integer.fraction,.fraction}[{e,E}[+,-]integer]
+ *
+ * Test each of these in turn, including invalid cases.
+ */
+typedef enum checkfp_state
+{
+ start, fraction, exponent, states
+} checkfp_state;
+
+/* The characters (other than digits) that characterize the states: */
+static const char none[] = "";
+static const char hexdigits[16] = "0123456789ABCDEF";
+
+static const struct
+{
+ const char *start; /* Characters valid at the start */
+ const char *end; /* Valid characters that end the state */
+ const char *tests; /* Characters to test after 2 digits seen */
+}
+state_characters[states] =
+{
+ /* start: */ { "+-.", ".eE", "+-.e*0369" },
+ /* fraction: */ { none, "eE", "+-.E#0147" },
+ /* exponent: */ { "+-", none, "+-.eE^0258" }
+};
+
+typedef struct
+{
+ char number[1024]; /* Buffer for number being tested */
+ int limit; /* Command line limit */
+ int verbose; /* Shadows global variable */
+ int ctimes; /* Number of numbers tested */
+ int cmillions; /* Count of millions of numbers */
+ int cinvalid; /* Invalid strings checked */
+ int cnoaccept; /* Characters not accepted */
+}
+checkfp_command;
+
+typedef struct
+{
+ int cnumber; /* Index into number string */
+ checkfp_state check_state; /* Current number state */
+ int at_start; /* At start (first character) of state */
+ int cdigits_in_state; /* Digits seen in that state */
+ int limit; /* Limit on same for checking all chars */
+ int state; /* Current parser state */
+ int is_negative; /* Number is negative */
+ int is_zero; /* Number is (still) zero */
+ int number_was_valid; /* Previous character validity */
+}
+checkfp_control;
+
+static int check_all_characters(checkfp_command *co, checkfp_control c);
+
+static int check_some_characters(checkfp_command *co, checkfp_control c,
+ const char *tests);
+
+static int check_one_character(checkfp_command *co, checkfp_control c, int ch)
+{
+ /* Test this character (ch) to ensure the parser does the correct thing.
+ */
+ png_size_t index = 0;
+ const char test = (char)ch;
+ const int number_is_valid = png_check_fp_number(&test, 1, &c.state, &index);
+ const int character_accepted = (index == 1);
+
+ if (c.check_state != exponent && isdigit(ch) && ch != '0')
+ c.is_zero = 0;
+
+ if (c.check_state == start && c.at_start && ch == '-')
+ c.is_negative = 1;
+
+ if (isprint(ch))
+ co->number[c.cnumber++] = (char)ch;
+ else
+ {
+ co->number[c.cnumber++] = '<';
+ co->number[c.cnumber++] = hexdigits[(ch >> 4) & 0xf];
+ co->number[c.cnumber++] = hexdigits[ch & 0xf];
+ co->number[c.cnumber++] = '>';
+ }
+ co->number[c.cnumber] = 0;
+
+ if (co->verbose > 1)
+ fprintf(stderr, "%s\n", co->number);
+
+ if (++(co->ctimes) == 1000000)
+ {
+ if (co->verbose == 1)
+ fputc('.', stderr);
+ co->ctimes = 0;
+ ++(co->cmillions);
+ }
+
+ if (!number_is_valid)
+ ++(co->cinvalid);
+
+ if (!character_accepted)
+ ++(co->cnoaccept);
+
+ /* This should never fail (it's a serious bug if it does): */
+ if (index != 0 && index != 1)
+ {
+ fprintf(stderr, "%s: read beyond end of string (%lu)\n", co->number,
+ (unsigned long)index);
+ return 0;
+ }
+
+ /* Validate the new state, note that the PNG_FP_IS_ macros all return
+ * false unless the number is valid.
+ */
+ if (PNG_FP_IS_NEGATIVE(c.state) !=
+ (number_is_valid && !c.is_zero && c.is_negative))
+ {
+ fprintf(stderr, "%s: negative when it is not\n", co->number);
+ return 0;
+ }
+
+ if (PNG_FP_IS_ZERO(c.state) != (number_is_valid && c.is_zero))
+ {
+ fprintf(stderr, "%s: zero when it is not\n", co->number);
+ return 0;
+ }
+
+ if (PNG_FP_IS_POSITIVE(c.state) !=
+ (number_is_valid && !c.is_zero && !c.is_negative))
+ {
+ fprintf(stderr, "%s: positive when it is not\n", co->number);
+ return 0;
+ }
+
+ /* Testing a digit */
+ if (isdigit(ch))
+ {
+ if (!character_accepted)
+ {
+ fprintf(stderr, "%s: digit '%c' not accepted\n", co->number, ch);
+ return 0;
+ }
+
+ if (!number_is_valid)
+ {
+ fprintf(stderr, "%s: saw a digit (%c) but number not valid\n",
+ co->number, ch);
+ return 0;
+ }
+
+ ++c.cdigits_in_state;
+ c.at_start = 0;
+ c.number_was_valid = 1;
+
+ /* Continue testing characters in this state. Either test all of
+ * them or, if we have already seen one digit in this state, just test a
+ * limited set.
+ */
+ if (c.cdigits_in_state < 1)
+ return check_all_characters(co, c);
+
+ else
+ return check_some_characters(co, c,
+ state_characters[c.check_state].tests);
+ }
+
+ /* A non-digit; is it allowed here? */
+ else if (((ch == '+' || ch == '-') && c.check_state != fraction &&
+ c.at_start) ||
+ (ch == '.' && c.check_state == start) ||
+ ((ch == 'e' || ch == 'E') && c.number_was_valid &&
+ c.check_state != exponent))
+ {
+ if (!character_accepted)
+ {
+ fprintf(stderr, "%s: character '%c' not accepted\n", co->number, ch);
+ return 0;
+ }
+
+ /* The number remains valid after start of fraction but nowhere else. */
+ if (number_is_valid && (c.check_state != start || ch != '.'))
+ {
+ fprintf(stderr, "%s: saw a non-digit (%c) but number valid\n",
+ co->number, ch);
+ return 0;
+ }
+
+ c.number_was_valid = number_is_valid;
+
+ /* Check for a state change. When changing to 'fraction' if the number
+ * is valid at this point set the at_start to false to allow an exponent
+ * 'e' to come next.
+ */
+ if (c.check_state == start && ch == '.')
+ {
+ c.check_state = fraction;
+ c.at_start = !number_is_valid;
+ c.cdigits_in_state = 0;
+ c.limit = co->limit;
+ return check_all_characters(co, c);
+ }
+
+ else if (c.check_state < exponent && (ch == 'e' || ch == 'E'))
+ {
+ c.check_state = exponent;
+ c.at_start = 1;
+ c.cdigits_in_state = 0;
+ c.limit = co->limit;
+ return check_all_characters(co, c);
+ }
+
+ /* Else it was a sign, and the state doesn't change. */
+ else
+ {
+ if (ch != '-' && ch != '+')
+ {
+ fprintf(stderr, "checkfp: internal error (1)\n");
+ return 0;
+ }
+
+ c.at_start = 0;
+ return check_all_characters(co, c);
+ }
+ }
+
+ /* Testing an invalid character */
+ else
+ {
+ if (character_accepted)
+ {
+ fprintf(stderr, "%s: character '%c' [0x%.2x] accepted\n", co->number,
+ ch, ch);
+ return 0;
+ }
+
+ if (number_is_valid != c.number_was_valid)
+ {
+ fprintf(stderr,
+ "%s: character '%c' [0x%.2x] changed number validity\n", co->number,
+ ch, ch);
+ return 0;
+ }
+
+ /* Do nothing - the parser has stuck; return success and keep going with
+ * the next character.
+ */
+ }
+
+ /* Successful return (the caller will try the next character.) */
+ return 1;
+}
+
+static int check_all_characters(checkfp_command *co, checkfp_control c)
+{
+ int ch;
+
+ if (c.cnumber+4 < sizeof co->number) for (ch=0; ch<256; ++ch)
+ {
+ if (!check_one_character(co, c, ch))
+ return 0;
+ }
+
+ return 1;
+}
+
+static int check_some_characters(checkfp_command *co, checkfp_control c,
+ const char *tests)
+{
+ int i;
+
+ --(c.limit);
+
+ if (c.cnumber+4 < sizeof co->number && c.limit >= 0)
+ {
+ if (c.limit > 0) for (i=0; tests[i]; ++i)
+ {
+ if (!check_one_character(co, c, tests[i]))
+ return 0;
+ }
+
+ /* At the end check all the characters. */
+ else
+ return check_all_characters(co, c);
+ }
+
+ return 1;
+}
+
+int validation_checkfp(int count, int argc, char **argv)
+{
+ int result;
+ checkfp_command command;
+ checkfp_control control;
+
+ command.number[0] = 0;
+ command.limit = 3;
+ command.verbose = verbose;
+ command.ctimes = 0;
+ command.cmillions = 0;
+ command.cinvalid = 0;
+ command.cnoaccept = 0;
+
+ while (--argc > 0)
+ {
+ ++argv;
+ if (argc > 1 && strcmp(*argv, "-l") == 0)
+ {
+ --argc;
+ command.limit = atoi(*++argv);
+ }
+
+ else
+ {
+ fprintf(stderr, "unknown argument %s\n", *argv);
+ return 1;
+ }
+ }
+
+ control.cnumber = 0;
+ control.check_state = start;
+ control.at_start = 1;
+ control.cdigits_in_state = 0;
+ control.limit = command.limit;
+ control.state = 0;
+ control.is_negative = 0;
+ control.is_zero = 1;
+ control.number_was_valid = 0;
+
+ result = check_all_characters(&command, control);
+
+ printf("checkfp: %s: checked %d,%.3d,%.3d,%.3d strings (%d invalid)\n",
+ result ? "pass" : "FAIL", command.cmillions / 1000,
+ command.cmillions % 1000, command.ctimes / 1000, command.ctimes % 1000,
+ command.cinvalid);
+
+ return result;
+}
+
+int validation_muldiv(int count, int argc, char **argv)
+{
+ int tested = 0;
+ int overflow = 0;
+ int error = 0;
+ int error64 = 0;
+ int passed = 0;
+ int randbits = 0;
+ png_uint_32 randbuffer;
+ png_fixed_point a;
+ png_int_32 times, div;
+
+ while (--argc > 0)
+ {
+ fprintf(stderr, "unknown argument %s\n", *++argv);
+ return 1;
+ }
+
+ /* Find out about the random number generator. */
+ randbuffer = RAND_MAX;
+ while (randbuffer != 0) ++randbits, randbuffer >>= 1;
+ printf("Using random number generator that makes %d bits\n", randbits);
+ for (div=0; div<32; div += randbits)
+ randbuffer = (randbuffer << randbits) ^ rand();
+
+ a = 0;
+ times = div = 0;
+ do
+ {
+ png_fixed_point result;
+ /* NOTE: your mileage may vary, a type is required below that can
+ * hold 64 bits or more, if floating point is used a 64-bit or
+ * better mantissa is required.
+ */
+ long long int fp, fpround;
+ unsigned long hi, lo;
+ int ok;
+
+ /* Check the values, png_64bit_product can only handle positive
+ * numbers, so correct for that here.
+ */
+ {
+ long u1, u2;
+ int n = 0;
+ if (a < 0) u1 = -a, n = 1; else u1 = a;
+ if (times < 0) u2 = -times, n = !n; else u2 = times;
+ png_64bit_product(u1, u2, &hi, &lo);
+ if (n)
+ {
+ /* -x = ~x+1 */
+ lo = ((~lo) + 1) & 0xffffffff;
+ hi = ~hi;
+ if (lo == 0) ++hi;
+ }
+ }
+
+ fp = a;
+ fp *= times;
+ if ((fp & 0xffffffff) != lo || ((fp >> 32) & 0xffffffff) != hi)
+ {
+ fprintf(stderr, "png_64bit_product %d * %d -> %lx|%.8lx not %llx\n",
+ a, times, hi, lo, fp);
+ ++error64;
+ }
+
+ if (div != 0)
+ {
+ /* Round - this is C round to zero. */
+ if ((fp < 0) != (div < 0))
+ fp -= div/2;
+ else
+ fp += div/2;
+
+ fp /= div;
+ fpround = fp;
+ /* Assume 2's complement here: */
+ ok = fpround <= PNG_UINT_31_MAX &&
+ fpround >= -1-(long long int)PNG_UINT_31_MAX;
+ if (!ok) ++overflow;
+ }
+ else
+ ok = 0, ++overflow, fpround = fp/*misleading*/;
+
+ if (verbose)
+ fprintf(stderr, "TEST %d * %d / %d -> %lld (%s)\n", a, times, div,
+ fp, ok ? "ok" : "overflow");
+
+ ++tested;
+ if (png_muldiv(&result, a, times, div) != ok)
+ {
+ ++error;
+ if (ok)
+ fprintf(stderr, "%d * %d / %d -> overflow (expected %lld)\n", a,
+ times, div, fp);
+ else
+ fprintf(stderr, "%d * %d / %d -> %d (expected overflow %lld)\n", a,
+ times, div, result, fp);
+ }
+ else if (ok && result != fpround)
+ {
+ ++error;
+ fprintf(stderr, "%d * %d / %d -> %d not %lld\n", a, times, div, result,
+ fp);
+ }
+ else
+ ++passed;
+
+ /* Generate three new values, this uses rand() and rand() only returns
+ * up to RAND_MAX.
+ */
+ /* CRUDE */
+ a += times;
+ times += div;
+ div = randbuffer;
+ randbuffer = (randbuffer << randbits) ^ rand();
+ }
+ while (--count > 0);
+
+ printf("%d tests including %d overflows, %d passed, %d failed (%d 64-bit "
+ "errors)\n", tested, overflow, passed, error, error64);
+ return 0;
+}
+
+/* When FP is on this just becomes a speed test - compile without FP to get real
+ * validation.
+ */
+#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+#define LN2 .000010576586617430806112933839 /* log(2)/65536 */
+#define L2INV 94548.46219969910586572651 /* 65536/log(2) */
+
+/* For speed testing, need the internal functions too: */
+static png_uint_32 png_log8bit(unsigned x)
+{
+ if (x > 0)
+ return (png_uint_32)floor(.5-log(x/255.)*L2INV);
+
+ return 0xffffffff;
+}
+
+static png_uint_32 png_log16bit(png_uint_32 x)
+{
+ if (x > 0)
+ return (png_uint_32)floor(.5-log(x/65535.)*L2INV);
+
+ return 0xffffffff;
+}
+
+static png_uint_32 png_exp(png_uint_32 x)
+{
+ return (png_uint_32)floor(.5 + exp(x * -LN2) * 0xffffffffU);
+}
+
+static png_byte png_exp8bit(png_uint_32 log)
+{
+ return (png_byte)floor(.5 + exp(log * -LN2) * 255);
+}
+
+static png_uint_16 png_exp16bit(png_uint_32 log)
+{
+ return (png_uint_16)floor(.5 + exp(log * -LN2) * 65535);
+}
+#endif /* FLOATING_ARITHMETIC */
+
+int validation_gamma(int argc, char **argv)
+{
+ double gamma[9] = { 2.2, 1.8, 1.52, 1.45, 1., 1/1.45, 1/1.52, 1/1.8, 1/2.2 };
+ double maxerr;
+ int i, silent=0, onlygamma=0;
+
+ /* Silence the output with -s, just test the gamma functions with -g: */
+ while (--argc > 0)
+ if (strcmp(*++argv, "-s") == 0)
+ silent = 1;
+ else if (strcmp(*argv, "-g") == 0)
+ onlygamma = 1;
+ else
+ {
+ fprintf(stderr, "unknown argument %s\n", *argv);
+ return 1;
+ }
+
+ if (!onlygamma)
+ {
+ /* First validate the log functions: */
+ maxerr = 0;
+ for (i=0; i<256; ++i)
+ {
+ double correct = -log(i/255.)/log(2.)*65536;
+ double error = png_log8bit(i) - correct;
+
+ if (i != 0 && fabs(error) > maxerr)
+ maxerr = fabs(error);
+
+ if (i == 0 && png_log8bit(i) != 0xffffffff ||
+ i != 0 && png_log8bit(i) != floor(correct+.5))
+ {
+ fprintf(stderr, "8-bit log error: %d: got %u, expected %f\n",
+ i, png_log8bit(i), correct);
+ }
+ }
+
+ if (!silent)
+ printf("maximum 8-bit log error = %f\n", maxerr);
+
+ maxerr = 0;
+ for (i=0; i<65536; ++i)
+ {
+ double correct = -log(i/65535.)/log(2.)*65536;
+ double error = png_log16bit(i) - correct;
+
+ if (i != 0 && fabs(error) > maxerr)
+ maxerr = fabs(error);
+
+ if (i == 0 && png_log16bit(i) != 0xffffffff ||
+ i != 0 && png_log16bit(i) != floor(correct+.5))
+ {
+ if (error > .68) /* By experiment error is less than .68 */
+ {
+ fprintf(stderr, "16-bit log error: %d: got %u, expected %f"
+ " error: %f\n", i, png_log16bit(i), correct, error);
+ }
+ }
+ }
+
+ if (!silent)
+ printf("maximum 16-bit log error = %f\n", maxerr);
+
+ /* Now exponentiations. */
+ maxerr = 0;
+ for (i=0; i<=0xfffff; ++i)
+ {
+ double correct = exp(-i/65536. * log(2.)) * (65536. * 65536);
+ double error = png_exp(i) - correct;
+
+ if (fabs(error) > maxerr)
+ maxerr = fabs(error);
+ if (fabs(error) > 1883) /* By experiment. */
+ {
+ fprintf(stderr, "32-bit exp error: %d: got %u, expected %f"
+ " error: %f\n", i, png_exp(i), correct, error);
+ }
+ }
+
+ if (!silent)
+ printf("maximum 32-bit exp error = %f\n", maxerr);
+
+ maxerr = 0;
+ for (i=0; i<=0xfffff; ++i)
+ {
+ double correct = exp(-i/65536. * log(2.)) * 255;
+ double error = png_exp8bit(i) - correct;
+
+ if (fabs(error) > maxerr)
+ maxerr = fabs(error);
+ if (fabs(error) > .50002) /* By experiment */
+ {
+ fprintf(stderr, "8-bit exp error: %d: got %u, expected %f"
+ " error: %f\n", i, png_exp8bit(i), correct, error);
+ }
+ }
+
+ if (!silent)
+ printf("maximum 8-bit exp error = %f\n", maxerr);
+
+ maxerr = 0;
+ for (i=0; i<=0xfffff; ++i)
+ {
+ double correct = exp(-i/65536. * log(2.)) * 65535;
+ double error = png_exp16bit(i) - correct;
+
+ if (fabs(error) > maxerr)
+ maxerr = fabs(error);
+ if (fabs(error) > .524) /* By experiment */
+ {
+ fprintf(stderr, "16-bit exp error: %d: got %u, expected %f"
+ " error: %f\n", i, png_exp16bit(i), correct, error);
+ }
+ }
+
+ if (!silent)
+ printf("maximum 16-bit exp error = %f\n", maxerr);
+ } /* !onlygamma */
+
+ /* Test the overall gamma correction. */
+ for (i=0; i<9; ++i)
+ {
+ unsigned j;
+ double g = gamma[i];
+ png_fixed_point gfp = floor(g * PNG_FP_1 + .5);
+
+ if (!silent)
+ printf("Test gamma %f\n", g);
+
+ maxerr = 0;
+ for (j=0; j<256; ++j)
+ {
+ double correct = pow(j/255., g) * 255;
+ png_byte out = png_gamma_8bit_correct(j, gfp);
+ double error = out - correct;
+
+ if (fabs(error) > maxerr)
+ maxerr = fabs(error);
+ if (out != floor(correct+.5))
+ {
+ fprintf(stderr, "8bit %d ^ %f: got %d expected %f error %f\n",
+ j, g, out, correct, error);
+ }
+ }
+
+ if (!silent)
+ printf("gamma %f: maximum 8-bit error %f\n", g, maxerr);
+
+ maxerr = 0;
+ for (j=0; j<65536; ++j)
+ {
+ double correct = pow(j/65535., g) * 65535;
+ png_uint_16 out = png_gamma_16bit_correct(j, gfp);
+ double error = out - correct;
+
+ if (fabs(error) > maxerr)
+ maxerr = fabs(error);
+ if (fabs(error) > 1.62)
+ {
+ fprintf(stderr, "16bit %d ^ %f: got %d expected %f error %f\n",
+ j, g, out, correct, error);
+ }
+ }
+
+ if (!silent)
+ printf("gamma %f: maximum 16-bit error %f\n", g, maxerr);
+ }
+
+ return 0;
+}
+
+/**************************** VALIDATION TESTS ********************************/
+/* Various validation routines are included herein, they require some
+ * definition for png_warning and png_error, seetings of VALIDATION:
+ *
+ * 1: validates the ASCII to floating point conversions
+ * 2: validates png_muldiv
+ * 3: accuracy test of fixed point gamma tables
+ */
+
+/* The following COUNT (10^8) takes about 1 hour on a 1GHz Pentium IV
+ * processor.
+ */
+#define COUNT 1000000000
+
+int main(int argc, char **argv)
+{
+ int count = COUNT;
+
+ while (argc > 1)
+ {
+ if (argc > 2 && strcmp(argv[1], "-c") == 0)
+ {
+ count = atoi(argv[2]);
+ argc -= 2;
+ argv += 2;
+ }
+
+ else if (strcmp(argv[1], "-v") == 0)
+ {
+ ++verbose;
+ --argc;
+ ++argv;
+ }
+
+ else
+ break;
+ }
+
+ if (count > 0 && argc > 1)
+ {
+ if (strcmp(argv[1], "ascii") == 0)
+ return validation_ascii_to_fp(count, argc-1, argv+1);
+ else if (strcmp(argv[1], "checkfp") == 0)
+ return validation_checkfp(count, argc-1, argv+1);
+ else if (strcmp(argv[1], "muldiv") == 0)
+ return validation_muldiv(count, argc-1, argv+1);
+ else if (strcmp(argv[1], "gamma") == 0)
+ return validation_gamma(argc-1, argv+1);
+ }
+
+ /* Bad argument: */
+ fprintf(stderr,
+ "usage: tarith [-v] [-c count] {ascii,muldiv,gamma} [args]\n");
+ fprintf(stderr, " arguments: ascii [-a (all results)] [-e error%%]\n");
+ fprintf(stderr, " checkfp [-l max-number-chars]\n");
+ fprintf(stderr, " muldiv\n");
+ fprintf(stderr, " gamma -s (silent) -g (only gamma; no log)\n");
+ return 1;
+}
diff --git a/libpng/contrib/libtests/timepng.c b/libpng/contrib/libtests/timepng.c
new file mode 100644
index 0000000..7c93797
--- /dev/null
+++ b/libpng/contrib/libtests/timepng.c
@@ -0,0 +1,303 @@
+/* timepng.c
+ *
+ * Copyright (c) 2013 John Cunningham Bowler
+ *
+ * Last changed in libpng 1.6.1 [March 28, 2013]
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * Load an arbitrary number of PNG files (from the command line, or, if there
+ * are no arguments on the command line, from stdin) then run a time test by
+ * reading each file by row. The test does nothing with the read result and
+ * does no transforms. The only output is a time as a floating point number of
+ * seconds with 9 decimal digits.
+ */
+#define _POSIX_C_SOURCE 199309L /* for clock_gettime */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <time.h>
+
+#if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H)
+# include <config.h>
+#endif
+
+/* Define the following to use this test against your installed libpng, rather
+ * than the one being built here:
+ */
+#ifdef PNG_FREESTANDING_TESTS
+# include <png.h>
+#else
+# include "../../png.h"
+#endif
+
+static int read_png(FILE *fp)
+{
+ png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,0,0,0);
+ png_infop info_ptr = NULL;
+ png_bytep row = NULL, display = NULL;
+
+ if (png_ptr == NULL)
+ return 0;
+
+ if (setjmp(png_jmpbuf(png_ptr)))
+ {
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+ if (row != NULL) free(row);
+ if (display != NULL) free(display);
+ return 0;
+ }
+
+ png_init_io(png_ptr, fp);
+
+ info_ptr = png_create_info_struct(png_ptr);
+ if (info_ptr == NULL)
+ png_error(png_ptr, "OOM allocating info structure");
+
+ png_read_info(png_ptr, info_ptr);
+
+ {
+ png_size_t rowbytes = png_get_rowbytes(png_ptr, info_ptr);
+
+ row = malloc(rowbytes);
+ display = malloc(rowbytes);
+
+ if (row == NULL || display == NULL)
+ png_error(png_ptr, "OOM allocating row buffers");
+
+ {
+ png_uint_32 height = png_get_image_height(png_ptr, info_ptr);
+ int passes = png_set_interlace_handling(png_ptr);
+ int pass;
+
+ png_start_read_image(png_ptr);
+
+ for (pass = 0; pass < passes; ++pass)
+ {
+ png_uint_32 y = height;
+
+ /* NOTE: this trashes the row each time; interlace handling won't
+ * work, but this avoids memory thrashing for speed testing.
+ */
+ while (y-- > 0)
+ png_read_row(png_ptr, row, display);
+ }
+ }
+ }
+
+ /* Make sure to read to the end of the file: */
+ png_read_end(png_ptr, info_ptr);
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+ free(row);
+ free(display);
+ return 1;
+}
+
+static int mytime(struct timespec *t)
+{
+ /* Do the timing using clock_gettime and the per-process timer. */
+ if (!clock_gettime(CLOCK_PROCESS_CPUTIME_ID, t))
+ return 1;
+
+ perror("CLOCK_PROCESS_CPUTIME_ID");
+ fprintf(stderr, "timepng: could not get the time\n");
+ return 0;
+}
+
+static int perform_one_test(FILE *fp, int nfiles)
+{
+ int i;
+ struct timespec before, after;
+
+ /* Clear out all errors: */
+ rewind(fp);
+
+ if (mytime(&before))
+ {
+ for (i=0; i<nfiles; ++i)
+ {
+ if (read_png(fp))
+ {
+ if (ferror(fp))
+ {
+ perror("temporary file");
+ fprintf(stderr, "file %d: error reading PNG data\n", i);
+ return 0;
+ }
+ }
+
+ else
+ {
+ perror("temporary file");
+ fprintf(stderr, "file %d: error from libpng\n", i);
+ return 0;
+ }
+ }
+ }
+
+ else
+ return 0;
+
+ if (mytime(&after))
+ {
+ /* Work out the time difference and print it - this is the only output,
+ * so flush it immediately.
+ */
+ unsigned long s = after.tv_sec - before.tv_sec;
+ long ns = after.tv_nsec - before.tv_nsec;
+
+ if (ns < 0)
+ {
+ --s;
+ ns += 1000000000;
+
+ if (ns < 0)
+ {
+ fprintf(stderr, "timepng: bad clock from kernel\n");
+ return 0;
+ }
+ }
+
+ printf("%lu.%.9ld\n", s, ns);
+ fflush(stdout);
+ if (ferror(stdout))
+ {
+ fprintf(stderr, "timepng: error writing output\n");
+ return 0;
+ }
+
+ /* Successful return */
+ return 1;
+ }
+
+ else
+ return 0;
+}
+
+static int add_one_file(FILE *fp, char *name)
+{
+ FILE *ip = fopen(name, "rb");
+
+ if (ip != NULL)
+ {
+ int ch;
+ for (;;)
+ {
+ ch = getc(ip);
+ if (ch == EOF) break;
+ putc(ch, fp);
+ }
+
+ if (ferror(ip))
+ {
+ perror(name);
+ fprintf(stderr, "%s: read error\n", name);
+ return 0;
+ }
+
+ (void)fclose(ip);
+
+ if (ferror(fp))
+ {
+ perror("temporary file");
+ fprintf(stderr, "temporary file write error\n");
+ return 0;
+ }
+ }
+
+ else
+ {
+ perror(name);
+ fprintf(stderr, "%s: open failed\n", name);
+ return 0;
+ }
+
+ return 1;
+}
+
+int main(int argc, char **argv)
+{
+ int ok = 0;
+ FILE *fp = tmpfile();
+
+ if (fp != NULL)
+ {
+ int err = 0;
+ int nfiles = 0;
+
+ if (argc > 1)
+ {
+ int i;
+
+ for (i=1; i<argc; ++i)
+ {
+ if (add_one_file(fp, argv[i]))
+ ++nfiles;
+
+ else
+ {
+ err = 1;
+ break;
+ }
+ }
+ }
+
+ else
+ {
+ char filename[FILENAME_MAX+1];
+
+ while (fgets(filename, FILENAME_MAX+1, stdin))
+ {
+ size_t len = strlen(filename);
+
+ if (filename[len-1] == '\n')
+ {
+ filename[len-1] = 0;
+ if (add_one_file(fp, filename))
+ ++nfiles;
+
+ else
+ {
+ err = 1;
+ break;
+ }
+ }
+
+ else
+ {
+ fprintf(stderr, "timepng: truncated file name ...%s\n",
+ filename+len-32);
+ err = 1;
+ break;
+ }
+ }
+
+ if (ferror(stdin))
+ {
+ fprintf(stderr, "timepng: stdin: read error\n");
+ err = 1;
+ }
+ }
+
+ if (!err)
+ {
+ if (nfiles > 0)
+ ok = perform_one_test(fp, nfiles);
+
+ else
+ fprintf(stderr, "usage: timepng {files} or ls files | timepng\n");
+ }
+
+ (void)fclose(fp);
+ }
+
+ else
+ fprintf(stderr, "timepng: could not open temporary file\n");
+
+ /* Exit code 0 on success. */
+ return ok == 0;
+}
diff --git a/libpng/contrib/pngminim/README b/libpng/contrib/pngminim/README
new file mode 100644
index 0000000..e17fe35
--- /dev/null
+++ b/libpng/contrib/pngminim/README
@@ -0,0 +1,5 @@
+
+This demonstrates the use of PNG_USER_CONFIG, pngusr.h and pngusr.dfa
+to build minimal decoder, encoder, and progressive reader applications.
+
+See the individual README and pngusr.dfa files for more explanation.
diff --git a/libpng/contrib/pngminim/decoder/README b/libpng/contrib/pngminim/decoder/README
new file mode 100644
index 0000000..fa979fc
--- /dev/null
+++ b/libpng/contrib/pngminim/decoder/README
@@ -0,0 +1,10 @@
+This demonstrates the use of PNG_USER_CONFIG, pngusr.h and pngusr.dfa
+
+The makefile builds a minimal read-only decoder with embedded libpng
+and zlib.
+
+Specify the location of the zlib source (1.2.1 or later) as ZLIBSRC
+on the make command line.
+
+If you prefer to use the shared libraries, go to contrib/pngminus
+and build the png2pnm application there.
diff --git a/libpng/contrib/pngminim/decoder/makefile b/libpng/contrib/pngminim/decoder/makefile
new file mode 100644
index 0000000..4acf3c1
--- /dev/null
+++ b/libpng/contrib/pngminim/decoder/makefile
@@ -0,0 +1,151 @@
+# Makefile for PngMinus (pngm2pnm)
+# Linux / Unix
+
+#CC=cc
+CC=gcc
+LD=$(CC)
+
+# If awk fails try
+# make AWK=nawk
+
+# If cpp fails try
+# make CPP=/lib/cpp
+
+RM=rm -f
+COPY=cp
+
+CPPFLAGS=-I. -DPNG_USER_CONFIG -DNO_GZCOMPRESS -DZ_SOLO -DNO_GZIP
+CFLAGS=-O1 -Wall
+
+C=.c
+O=.o
+L=.a
+E=
+
+# Where to find the source code:
+PNGSRC =../../..
+ZLIBSRC=$(PNGSRC)/../zlib
+PROGSRC=$(PNGSRC)/contrib/pngminus
+
+# Zlib (minimal inflate requirements - crc32 is used by libpng)
+# zutil can be eliminated if you provide your own zcalloc and zcfree
+ZSRCS = adler32$(C) crc32$(C) \
+ inffast$(C) inflate$(C) inftrees$(C) \
+ zutil$(C)
+
+# Standard headers
+ZH = zlib.h crc32.h inffast.h inffixed.h \
+ inflate.h inftrees.h zutil.h
+
+# Machine generated headers
+ZCONF = zconf.h
+
+# Headers callers use
+ZINC = zlib.h $(ZCONF)
+
+# Headers the Zlib source uses
+ZHDRS = $(ZH) $(ZCONF)
+
+ZOBJS = adler32$(O) crc32$(O) \
+ inffast$(O) inflate$(O) inftrees$(O) \
+ zutil$(O)
+
+# libpng
+PNGSRCS=png$(C) pngerror$(C) pngget$(C) pngmem$(C) \
+ pngread$(C) pngrio$(C) pngrtran$(C) pngrutil$(C) \
+ pngset$(C) pngtrans$(C)
+
+# Standard headers
+PNGH =png.h pngconf.h pngdebug.h pnginfo.h pngpriv.h pngstruct.h
+
+# Machine generated headers
+PNGCONF=pnglibconf.h
+
+# Headers callers use
+PNGINC= png.h pngconf.h pngusr.h $(PNGCONF)
+
+# Headers the PNG library uses
+PNGHDRS=$(PNGH) $(PNGCONF) pngusr.h
+
+PNGOBJS=png$(O) pngerror$(O) pngget$(O) pngmem$(O) \
+ pngread$(O) pngrio$(O) pngrtran$(O) pngrutil$(O) \
+ pngset$(O) pngtrans$(O)
+
+PROGSRCS= pngm2pnm$(C)
+PROGHDRS=
+PROGDOCS=
+PROGOBJS= pngm2pnm$(O)
+
+OBJS = $(PROGOBJS) $(PNGOBJS) $(ZOBJS)
+
+# implicit make rules -------------------------------------------------------
+
+# note: dependencies do not work on implicit rule lines
+.c$(O):
+ $(CC) -c $(CPPFLAGS) $(CFLAGS) $<
+
+# dependencies
+
+all: pngm2pnm$(E)
+
+pngm2pnm$(E): $(OBJS)
+ $(LD) -o pngm2pnm$(E) $(OBJS)
+
+# The DFA_XTRA setting turns all libpng options off then
+# turns on those required for this minimal build.
+# The CPP_FLAGS setting causes pngusr.h to be included in
+# both the build of pnglibconf.h and, subsequently, when
+# building libpng itself.
+$(PNGCONF): $(PNGSRC)/scripts/pnglibconf.mak $(ZH)\
+ $(PNGSRC)/scripts/pnglibconf.dfa \
+ $(PNGSRC)/scripts/options.awk pngusr.h pngusr.dfa
+ $(RM) pnglibconf.h pnglibconf.dfn
+ $(MAKE) -f $(PNGSRC)/scripts/pnglibconf.mak $(MAKEFLAGS)\
+ srcdir=$(PNGSRC) CPPFLAGS="-DPNG_USER_CONFIG -I."\
+ DFA_XTRA="pngusr.dfa" $@
+
+clean:
+ $(MAKE) -f $(PNGSRC)/scripts/pnglibconf.mak $(MAKEFLAGS)\
+ srcdir=$(PNGSRC) clean
+ $(RM) pngm2pnm$(O)
+ $(RM) pngm2pnm$(E)
+ $(RM) $(OBJS)
+
+# distclean also removes the copied source and headers
+distclean: clean
+ $(RM) -r scripts # historical reasons
+ $(RM) $(PNGSRCS) $(PNGH)
+ $(RM) $(ZSRCS) $(ZH) $(ZCONF)
+ $(RM) $(PROGSRCS) $(PROGHDRS) $(PROGDOCS)
+
+# Header file dependencies:
+$(PROGOBJS): $(PROGHDRS) $(PNGINC) $(ZINC)
+$(PNGOBJS): $(PNGHDRS) $(ZINC)
+$(ZOBJS): $(ZHDRS)
+
+# Gather the source code from the respective directories
+$(PNGSRCS) $(PNGH): $(PNGSRC)/$@
+ $(RM) $@
+ $(COPY) $(PNGSRC)/$@ $@
+
+# No dependency on the ZLIBSRC target so that it only needs
+# to be specified once.
+$(ZSRCS) $(ZH):
+ $(RM) $@
+ $(COPY) $(ZLIBSRC)/$@ $@
+
+# The unconfigured zconf.h varies in name according to the
+# zlib release
+$(ZCONF):
+ $(RM) $@
+ @for f in zconf.h.in zconf.in.h zconf.h; do\
+ test -r $(ZLIBSRC)/$$f &&\
+ echo $(COPY) $(ZLIBSRC)/$$f $@ &&\
+ $(COPY) $(ZLIBSRC)/$$f $@ && exit 0;\
+ done; echo copy: $(ZLIBSRC)/zconf.h not found; exit 1
+
+pngm2pnm.c: $(PROGSRC)/png2pnm.c
+ $(RM) $@
+ $(COPY) $(PROGSRC)/png2pnm.c $@
+
+# End of makefile for pngm2pnm
diff --git a/libpng/contrib/pngminim/decoder/pngusr.dfa b/libpng/contrib/pngminim/decoder/pngusr.dfa
new file mode 100644
index 0000000..4f40272
--- /dev/null
+++ b/libpng/contrib/pngminim/decoder/pngusr.dfa
@@ -0,0 +1,40 @@
+# pngminim/decoder/pngusr.dfa
+#
+# Copyright (c) 2010-2013 Glenn Randers-Pehrson
+#
+# This code is released under the libpng license.
+# For conditions of distribution and use, see the disclaimer
+# and license in png.h
+
+# First all the build options off:
+
+everything = off
+
+# All that is required is some read code. This example switches
+# on the sequential read code (see ../preader for a progressive
+# read example).
+
+option SEQUENTIAL_READ on
+
+# You must choose fixed or floating point arithmetic:
+# option FLOATING_POINT on
+
+option FIXED_POINT on
+
+# You must chose the internal fixed point implementation or to
+# use the system floating point. The latter is considerably
+# smaller (by about 1kbyte on an x86 system):
+# option FLOATING_ARITHMETIC on
+
+option FLOATING_ARITHMETIC off
+
+# Your program will probably need other options. The example
+# program here, pngm2pnm, requires the following. Take a look
+# at pnglibconf.h to find out the full set of what has to be
+# enabled to make the following work.
+
+option SETJMP on
+option STDIO on
+option READ_EXPAND on
+option READ_STRIP_16_TO_8 on
+option USER_LIMITS on
diff --git a/libpng/contrib/pngminim/decoder/pngusr.h b/libpng/contrib/pngminim/decoder/pngusr.h
new file mode 100644
index 0000000..cbd7890
--- /dev/null
+++ b/libpng/contrib/pngminim/decoder/pngusr.h
@@ -0,0 +1,23 @@
+/* minrdpngconf.h: headers to make a minimal png-read-only library
+ *
+ * Copyright (c) 2007, 2010-2013 Glenn Randers-Pehrson
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * Derived from pngcrush.h, Copyright 1998-2007, Glenn Randers-Pehrson
+ */
+
+#ifndef MINRDPNGCONF_H
+#define MINRDPNGCONF_H
+
+/* To include pngusr.h set -DPNG_USER_CONFIG in CPPFLAGS */
+
+/* List options to turn off features of the build that do not
+ * affect the API (so are not recorded in pnglibconf.h)
+ */
+
+#define PNG_ALIGN_TYPE PNG_ALIGN_NONE
+
+#endif /* MINRDPNGCONF_H */
diff --git a/libpng/contrib/pngminim/encoder/README b/libpng/contrib/pngminim/encoder/README
new file mode 100644
index 0000000..d8d9a64
--- /dev/null
+++ b/libpng/contrib/pngminim/encoder/README
@@ -0,0 +1,10 @@
+This demonstrates the use of PNG_USER_CONFIG and pngusr.h
+
+The makefile builds a minimal write-only encoder with embedded libpng
+and zlib.
+
+Specify the location of the zlib source (1.2.1 or later) as ZLIBSRC
+on the make command line.
+
+If you prefer to use the shared libraries, go to contrib/pngminus
+and build the pnm2png application there.
diff --git a/libpng/contrib/pngminim/encoder/makefile b/libpng/contrib/pngminim/encoder/makefile
new file mode 100644
index 0000000..41b205c
--- /dev/null
+++ b/libpng/contrib/pngminim/encoder/makefile
@@ -0,0 +1,150 @@
+# Makefile for PngMinus (pnm2pngm)
+# Linux / Unix
+
+#CC=cc
+CC=gcc
+LD=$(CC)
+
+# If awk fails try
+# make AWK=nawk
+
+# If cpp fails try
+# make CPP=/lib/cpp
+
+RM=rm -f
+COPY=cp
+
+CPPFLAGS=-I. -DPNG_USER_CONFIG -DNO_GZCOMPRESS -DZ_SOLO -DNO_GZIP
+CFLAGS=-O1 -Wall
+
+C=.c
+O=.o
+L=.a
+E=
+
+# Where to find the source code:
+PNGSRC =../../..
+ZLIBSRC=$(PNGSRC)/../zlib
+PROGSRC=$(PNGSRC)/contrib/pngminus
+
+# Zlib
+ZSRCS = adler32$(C) compress$(C) crc32$(C) deflate$(C) \
+ trees$(C) zutil$(C)
+
+# Standard headers
+#ZH = zlib.h crc32.h deflate.h trees.h zutil.h
+ZH = zlib.h crc32.h deflate.h trees.h zutil.h
+
+# Machine generated headers
+ZCONF = zconf.h
+
+# Headers callers use
+ZINC = zlib.h $(ZCONF)
+
+# Headers the Zlib source uses
+ZHDRS = $(ZH) $(ZCONF)
+
+# compress is not required; it is needed to link the zlib
+# code because deflate defines an unused API function deflateBound
+# which itself calls compressBound from compress.
+ZOBJS = adler32$(O) compress$(O) crc32$(O) deflate$(O) \
+ trees$(O) zutil$(O)
+
+# libpng
+PNGSRCS=png$(C) pngerror$(C) pngget$(C) pngmem$(C) \
+ pngset$(C) pngtrans$(C) pngwio$(C) pngwrite$(C) \
+ pngwtran$(C) pngwutil$(C)
+
+# Standard headers
+PNGH =png.h pngconf.h pngdebug.h pnginfo.h pngpriv.h pngstruct.h
+
+# Machine generated headers
+PNGCONF=pnglibconf.h
+
+# Headers callers use
+PNGINC= png.h pngconf.h pngusr.h $(PNGCONF)
+
+# Headers the PNG library uses
+PNGHDRS=$(PNGH) $(PNGCONF) pngusr.h
+
+PNGOBJS=png$(O) pngerror$(O) pngget$(O) pngmem$(O) \
+ pngset$(O) pngtrans$(O) pngwio$(O) pngwrite$(O) \
+ pngwtran$(O) pngwutil$(O)
+
+PROGSRCS= pnm2pngm$(C)
+PROGHDRS=
+PROGDOCS=
+PROGOBJS= pnm2pngm$(O)
+
+OBJS = $(PROGOBJS) $(PNGOBJS) $(ZOBJS)
+
+# implicit make rules -------------------------------------------------------
+
+.c$(O):
+ $(CC) -c $(CPPFLAGS) $(CFLAGS) $<
+
+# dependencies
+
+all: pnm2pngm$(E)
+
+pnm2pngm$(E): $(OBJS)
+ $(LD) -o pnm2pngm$(E) $(OBJS)
+
+# The DFA_XTRA setting turns all libpng options off then
+# turns on those required for this minimal build.
+# The CPP_FLAGS setting causes pngusr.h to be included in
+# both the build of pnglibconf.h and, subsequently, when
+# building libpng itself.
+$(PNGCONF): $(PNGSRC)/scripts/pnglibconf.mak $(ZH)\
+ $(PNGSRC)/scripts/pnglibconf.dfa \
+ $(PNGSRC)/scripts/options.awk pngusr.h pngusr.dfa
+ $(RM) pnglibconf.h pnglibconf.dfn
+ $(MAKE) -f $(PNGSRC)/scripts/pnglibconf.mak $(MAKEFLAGS)\
+ srcdir=$(PNGSRC) CPPFLAGS="-DPNG_USER_CONFIG -I."\
+ DFA_XTRA="pngusr.dfa" $@
+
+clean:
+ $(MAKE) -f $(PNGSRC)/scripts/pnglibconf.mak $(MAKEFLAGS)\
+ srcdir=$(PNGSRC) clean
+ $(RM) pnm2pngm$(O)
+ $(RM) pnm2pngm$(E)
+ $(RM) $(OBJS)
+
+# distclean also removes the copied source and headers
+distclean: clean
+ $(RM) -r scripts # historical reasons
+ $(RM) $(PNGSRCS) $(PNGH)
+ $(RM) $(ZSRCS) $(ZH) $(ZCONF)
+ $(RM) $(PROGSRCS) $(PROGHDRS) $(PROGDOCS)
+
+# Header file dependencies:
+$(PROGOBJS): $(PROGHDRS) $(PNGINC) $(ZINC)
+$(PNGOBJS): $(PNGHDRS) $(ZINC)
+$(ZOBJS): $(ZHDRS)
+
+# Gather the source code from the respective directories
+$(PNGSRCS) $(PNGH): $(PNGSRC)/$@
+ $(RM) $@
+ $(COPY) $(PNGSRC)/$@ $@
+
+# No dependency on the ZLIBSRC target so that it only needs
+# to be specified once.
+$(ZSRCS) $(ZH):
+ $(RM) $@
+ $(COPY) $(ZLIBSRC)/$@ $@
+
+# The unconfigured zconf.h varies in name according to the
+# zlib release
+$(ZCONF):
+ $(RM) $@
+ @for f in zconf.h.in zconf.in.h zconf.h; do\
+ test -r $(ZLIBSRC)/$$f &&\
+ echo $(COPY) $(ZLIBSRC)/$$f $@ &&\
+ $(COPY) $(ZLIBSRC)/$$f $@ && exit 0;\
+ done; echo copy: $(ZLIBSRC)/zconf.h not found; exit 1
+
+pnm2pngm.c: $(PROGSRC)/pnm2png.c
+ $(RM) $@
+ $(COPY) $(PROGSRC)/pnm2png.c $@
+
+# End of makefile for pnm2pngm
diff --git a/libpng/contrib/pngminim/encoder/pngusr.dfa b/libpng/contrib/pngminim/encoder/pngusr.dfa
new file mode 100644
index 0000000..1fc24f3
--- /dev/null
+++ b/libpng/contrib/pngminim/encoder/pngusr.dfa
@@ -0,0 +1,39 @@
+# pngminim/encoder/pngusr.dfa
+#
+# Copyright (c) 2010-2013 Glenn Randers-Pehrson
+#
+# This code is released under the libpng license.
+# For conditions of distribution and use, see the disclaimer
+# and license in png.h
+
+# First all the build options off:
+
+everything = off
+
+# Switch on the write code - this makes a minimalist encoder
+
+option WRITE on
+
+# These 2 options are required if you need to read PBM (P1 or P4) files.
+option WRITE_INVERT on
+option WRITE_PACK on
+
+# You must choose fixed or floating point arithmetic:
+# option FLOATING_POINT on
+
+option FIXED_POINT on
+
+# You must chose the internal fixed point implementation or to
+# use the system floating point. The latter is considerably
+# smaller (by about 1kbyte on an x86 system):
+# option FLOATING_ARITHMETIC on
+
+option FLOATING_ARITHMETIC off
+
+# Your program will probably need other options. The example
+# program here, pnm2pngm, requires the following. Take a look
+# at pnglibconf.h to find out the full set of what has to be
+# enabled to make the following work.
+
+option SETJMP on
+option STDIO on
diff --git a/libpng/contrib/pngminim/encoder/pngusr.h b/libpng/contrib/pngminim/encoder/pngusr.h
new file mode 100644
index 0000000..997d44f
--- /dev/null
+++ b/libpng/contrib/pngminim/encoder/pngusr.h
@@ -0,0 +1,23 @@
+/* minwrpngconf.h: headers to make a minimal png-write-only library
+ *
+ * Copyright (c) 2007, 2010-2013 Glenn Randers-Pehrson
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * Derived from pngcrush.h, Copyright 1998-2007, Glenn Randers-Pehrson
+ */
+
+#ifndef MINWRPNGCONF_H
+#define MINWRPNGCONF_H
+
+/* To include pngusr.h set -DPNG_USER_CONFIG in CPPFLAGS */
+
+/* List options to turn off features of the build that do not
+ * affect the API (so are not recorded in pnglibconf.h)
+ */
+
+#define PNG_ALIGN_TYPE PNG_ALIGN_NONE
+
+#endif /* MINWRPNGCONF_H */
diff --git a/libpng/contrib/pngminim/preader/README b/libpng/contrib/pngminim/preader/README
new file mode 100644
index 0000000..faa8356
--- /dev/null
+++ b/libpng/contrib/pngminim/preader/README
@@ -0,0 +1,15 @@
+This demonstrates the use of PNG_USER_CONFIG and pngusr.h
+
+The makefile builds a minimal read-only progressive decoder with
+embedded libpng, zlib and your system's X library.
+
+Specify the location of the zlib source (1.2.1 or later) as ZLIBSRC
+on the make command line.
+
+Edit makefile if required, to find your X library and include files,
+then
+
+ make ZLIBSRC=directory
+
+If you prefer to use the shared libraries, go to contrib/gregbook
+and build the rpng2-x application there.
diff --git a/libpng/contrib/pngminim/preader/makefile b/libpng/contrib/pngminim/preader/makefile
new file mode 100644
index 0000000..b625199
--- /dev/null
+++ b/libpng/contrib/pngminim/preader/makefile
@@ -0,0 +1,166 @@
+# Makefile for PngMinus (rpng2)
+# Linux / Unix
+
+#CC=cc
+CC=gcc
+LD=$(CC)
+
+# If awk fails try
+# make AWK=nawk
+
+# If cpp fails try
+# make CPP=/lib/cpp
+
+RM=rm -f
+COPY=cp
+
+#XINC = -I/usr/include # old-style, stock X distributions
+#XLIB = -L/usr/lib/X11 -lX11 # (including SGI IRIX)
+
+#XINC = -I/usr/openwin/include # Sun workstations (OpenWindows)
+#XLIB = -L/usr/openwin/lib -lX11
+
+XINC = -I/usr/X11R6/include # new X distributions (X.org, etc.)
+XLIB = -L/usr/X11R6/lib -lX11
+#XLIB = -L/usr/X11R6/lib64 -lX11 # e.g., Red Hat on AMD64
+
+#XINC = -I/usr/local/include # FreeBSD
+#XLIB = -L/usr/local/lib -lX11
+
+#LIBS = $(XLIB)
+LIBS = $(XLIB) -lm #platforms that need libm
+
+CPPFLAGS=-I. $(XINC) -DPNG_USER_CONFIG -DNO_GZCOMPRESS -DZ_SOLO -DNO_GZIP
+CFLAGS=-O1 -Wall
+
+C=.c
+O=.o
+L=.a
+E=
+
+# Where to find the source code:
+PNGSRC =../../..
+ZLIBSRC=$(PNGSRC)/../zlib
+PROGSRC=$(PNGSRC)/contrib/gregbook
+
+# Zlib (minimal inflate requirements - crc32 is used by libpng)
+# zutil can be eliminated if you provide your own zcalloc and zcfree
+ZSRCS = adler32$(C) crc32$(C) \
+ inffast$(C) inflate$(C) inftrees$(C) \
+ zutil$(C)
+
+# Standard headers
+ZH = zlib.h crc32.h inffast.h inffixed.h \
+ inflate.h inftrees.h zutil.h
+
+# Machine generated headers
+ZCONF = zconf.h
+
+# Headers callers use
+ZINC = zlib.h $(ZCONF)
+
+# Headers the Zlib source uses
+ZHDRS = $(ZH) $(ZCONF)
+
+ZOBJS = adler32$(O) crc32$(O) \
+ inffast$(O) inflate$(O) inftrees$(O) \
+ zutil$(O)
+
+# libpng
+PNGSRCS=png$(C) pngerror$(C) pngget$(C) pngmem$(C) \
+ pngpread$(C) pngread$(C) pngrio$(C) pngrtran$(C) pngrutil$(C) \
+ pngset$(C) pngtrans$(C)
+
+# Standard headers
+PNGH =png.h pngconf.h pngdebug.h pnginfo.h pngpriv.h pngstruct.h
+
+# Machine generated headers
+PNGCONF=pnglibconf.h
+
+# Headers callers use
+PNGINC= png.h pngconf.h pngusr.h $(PNGCONF)
+
+# Headers the PNG library uses
+PNGHDRS=$(PNGH) $(PNGCONF) pngusr.h
+
+PNGOBJS=png$(O) pngerror$(O) pngget$(O) pngmem$(O) \
+ pngpread$(O) pngread$(O) pngrio$(O) pngrtran$(O) pngrutil$(O) \
+ pngset$(O) pngtrans$(O)
+
+PROGSRCS= rpng2-x$(C) readpng2$(C)
+PROGHDRS= readpng2.h
+PROGDOCS= COPYING LICENSE
+PROGOBJS= rpng2-x$(O) readpng2$(O)
+
+OBJS = $(PROGOBJS) $(PNGOBJS) $(ZOBJS)
+
+# implicit make rules -------------------------------------------------------
+
+.c$(O):
+ $(CC) -c $(CPPFLAGS) $(CFLAGS) $<
+
+# dependencies
+
+all: $(PROGDOCS) rpng2-x$(E)
+
+rpng2-x$(E): $(OBJS)
+ $(LD) -o rpng2-x$(E) $(OBJS) $(LIBS)
+
+# The DFA_XTRA setting turns all libpng options off then
+# turns on those required for this minimal build.
+# The CPP_FLAGS setting causes pngusr.h to be included in
+# both the build of pnglibconf.h and, subsequently, when
+# building libpng itself.
+$(PNGCONF): $(PNGSRC)/scripts/pnglibconf.mak $(ZH)\
+ $(PNGSRC)/scripts/pnglibconf.dfa \
+ $(PNGSRC)/scripts/options.awk pngusr.h pngusr.dfa
+ $(RM) pnglibconf.h pnglibconf.dfn
+ $(MAKE) -f $(PNGSRC)/scripts/pnglibconf.mak $(MAKEFLAGS)\
+ srcdir=$(PNGSRC) CPPFLAGS="-DPNG_USER_CONFIG -I."\
+ DFA_XTRA="pngusr.dfa" $@
+
+clean:
+ $(MAKE) -f $(PNGSRC)/scripts/pnglibconf.mak $(MAKEFLAGS)\
+ srcdir=$(PNGSRC) clean
+ $(RM) rpng2-x$(O)
+ $(RM) rpng2-x$(E)
+ $(RM) $(OBJS)
+
+# distclean also removes the copied source and headers
+distclean: clean
+ $(RM) -r scripts # historical reasons
+ $(RM) $(PNGSRCS) $(PNGH)
+ $(RM) $(ZSRCS) $(ZH) $(ZCONF)
+ $(RM) $(PROGSRCS) $(PROGHDRS) $(PROGDOCS)
+
+# Header file dependencies:
+$(PROGOBJS): $(PROGHDRS) $(PNGINC) $(ZINC)
+$(PNGOBJS): $(PNGHDRS) $(ZINC)
+$(ZOBJS): $(ZHDRS)
+
+# Gather the source code from the respective directories
+$(PNGSRCS) $(PNGH): $(PNGSRC)/$@
+ $(RM) $@
+ $(COPY) $(PNGSRC)/$@ $@
+
+# No dependency on the ZLIBSRC target so that it only needs
+# to be specified once.
+$(ZSRCS) $(ZH):
+ $(RM) $@
+ $(COPY) $(ZLIBSRC)/$@ $@
+
+# The unconfigured zconf.h varies in name according to the
+# zlib release
+$(ZCONF):
+ $(RM) $@
+ @for f in zconf.h.in zconf.in.h zconf.h; do\
+ test -r $(ZLIBSRC)/$$f &&\
+ echo $(COPY) $(ZLIBSRC)/$$f $@ &&\
+ $(COPY) $(ZLIBSRC)/$$f $@ && exit 0;\
+ done; echo copy: $(ZLIBSRC)/zconf.h not found; exit 1
+
+$(PROGSRCS) $(PROGHDRS) $(PROGDOCS): $(PROGSRC)/$@
+ $(RM) $@
+ $(COPY) $(PROGSRC)/$@ $@
+
+# End of makefile for rpng2-x
diff --git a/libpng/contrib/pngminim/preader/pngusr.dfa b/libpng/contrib/pngminim/preader/pngusr.dfa
new file mode 100644
index 0000000..ac297f4
--- /dev/null
+++ b/libpng/contrib/pngminim/preader/pngusr.dfa
@@ -0,0 +1,40 @@
+# pngminim/preader/pngusr.dfa
+#
+# Copyright (c) 2010-2013 Glenn Randers-Pehrson
+#
+# This code is released under the libpng license.
+# For conditions of distribution and use, see the disclaimer
+# and license in png.h
+
+# First all the build options off:
+
+everything = off
+
+# Just switch on the progressive read code
+
+option PROGRESSIVE_READ on
+
+# You may choose fixed or floating point APIs:
+# option FLOATING_POINT on
+
+option FIXED_POINT on
+
+# You must chose the internal fixed point implementation or to
+# use the system floating point. The latter is considerably
+# smaller (by about 1kbyte on an x86 system):
+
+option FLOATING_ARITHMETIC on
+# option FLOATING_ARITHMETIC off
+
+# Your program will probably need other options. The example
+# program here, rpng2-x, requires the following. Take a look
+# at pnglibconf.h to find out the full set of what has to be
+# enabled to make the following work.
+
+option SETJMP on
+option STDIO on
+option READ_bKGD on
+option READ_GAMMA on
+option READ_EXPAND on
+option READ_STRIP_16_TO_8 on
+option READ_GRAY_TO_RGB on
diff --git a/libpng/contrib/pngminim/preader/pngusr.h b/libpng/contrib/pngminim/preader/pngusr.h
new file mode 100644
index 0000000..80db3bb
--- /dev/null
+++ b/libpng/contrib/pngminim/preader/pngusr.h
@@ -0,0 +1,23 @@
+/* minrdpngconf.h: headers to make a minimal png-read-only library
+ *
+ * Copyright (c) 2009, 2010-2013 Glenn Randers-Pehrson
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * Derived from pngcrush.h, Copyright 1998-2007, Glenn Randers-Pehrson
+ */
+
+#ifndef MINPRDPNGCONF_H
+#define MINPRDPNGCONF_H
+
+/* To include pngusr.h set -DPNG_USER_CONFIG in CPPFLAGS */
+
+/* List options to turn off features of the build that do not
+ * affect the API (so are not recorded in pnglibconf.h)
+ */
+
+#define PNG_ALIGN_TYPE PNG_ALIGN_NONE
+
+#endif /* MINPRDPNGCONF_H */
diff --git a/libpng/contrib/pngminus/README b/libpng/contrib/pngminus/README
new file mode 100644
index 0000000..bbe7407
--- /dev/null
+++ b/libpng/contrib/pngminus/README
@@ -0,0 +1,153 @@
+PngMinus
+--------
+(copyright Willem van Schaik, 1999)
+
+
+License
+-------
+
+Permission to use, copy, modify, and distribute this software and
+its documentation for any purpose and without fee is hereby granted,
+provided that the above copyright notice appear in all copies and
+that both that copyright notice and this permission notice appear in
+supporting documentation. This software is provided "as is" without
+express or implied warranty.
+
+
+Some history
+------------
+Soon after the creation of PNG in 1995, the need was felt for a set of
+pnmtopng / pngtopnm utilities. Independantly Alexander Lehmann and I
+(Willem van Schaik) started such a project. Luckily we discovered this
+and merged the two together into pnmtopng.tar.gz, which is available
+from a/o ftp://ftp.simplesystems.org/pub/libpng/png/.
+
+These two utilities have many, many options and make use of most of the
+features of PNG, like gamma, alpha, sbit, text-chunks, etc. This makes
+the utilities quite complex and by now not anymore very maintainable.
+When we wrote these programs, libpng was still in an early stage.
+Therefore, lots of the functionality that we put in our software can now
+be done using transform-functions in libpng.
+
+Finally, to compile these programs, you need to have installed and
+compiled three libraries: libpng, zlib and netpbm. Especially the latter
+makes the whole setup a bit bulky. But that's unavoidable given the many
+features of pnmtopng.
+
+
+What now
+--------
+At this moment libpng is in a very stable state and can do much of the
+work done in pnmtopng. Also, pnmtopng needs to be upgraded to the new
+interface of libpng. Hence, it is time for a rewrite from the ground up
+of pnmtopng and pngtopnm. This will happen in the near future (stay
+tuned). The new package will get a different name to distinguish it from
+the old one: PngPlus.
+
+To experiment a bit with the new interface of libpng, I started off with
+a small prototype that contains only the basic functionality. It doesn't
+have any of the options to read or write special chunks and it will do
+no gamma correction. But this makes it also a simple program that is
+quite easy to understand and can serve well as a template for other
+software developments. (By now there are of course a couple of programs,
+like Greg Roelofs' rpng/wpng, that can be used just as good.)
+
+
+Can and can not
+---------------
+As this is the small brother of the future PngPlus, I called this fellow
+PngMinus. Because I started this development in good-old Turbo-C, I
+avoided the use the netpbm library, which requires DOS extenders. Again,
+another reason to call it PngMinus (minus netpbm :-). So, part of the
+program are some elementary routines to read / write pgm- and ppm-files.
+It does not read b&w pbm-files.
+
+The downside of this approach is that you can not use them on images
+that require blocks of memory bigger than 64k (the DOS version). For
+larger images you will get an out-of-memory error.
+
+As said before, PngMinus doesn't correct for gamma. When reading
+png-files you can do this just as well by piping the output of png2pnm
+to pnmgamma, one of the standard PbmPlus tools. This same scenario will
+most probably also be followed in the full-blown future PngPlus, with
+the addition of course of the possibility to create gamma-chunks when
+writing png-files.
+
+On the other hand it supports alpha-channels. When reading a png-image
+you can write the alpha-channel into a pgm-file. And when creating an
+RGB+A png-image, you just combine a ppm-file with a corresponding
+pgm-file containing the alpha-channel. When reading, transparency chunks
+are converted into an alpha-channel and from there on treated the same
+way.
+
+Finally you can opt for writing ascii or binary pgm- and ppm-files. When
+the bit-depth is 16, the format will always be ascii.
+
+
+Using it
+--------
+To distinguish them from pnmtopng and PngPlus, the utilities are named
+png2pnm and pnm2png (2 instead of to). The input- and output-files can
+be given as parameters or through redirection. Therefore the programs
+can be part of a pipe.
+
+To list the options type "png2pnm -h" or "pnm2png -h".
+
+
+Just like Scandinavian furniture
+--------------------------------
+You have to put it together yourself. I did test the software under
+MS-DOS with Turbo-C 3.0 and under RedHat Linux 4.2 with gcc. In both
+cases I used libpng-1.0.4 and zlib-1.1.3. Later versions should be OK,
+however some older libpng versions have a bug in pngmem.c when using
+Turbo-C 3.0 (see below).
+
+You can build it using one of the two makefiles (make -f makefile.###)
+or use the batch/script files pngminus.bat / pngminus.sh. This assumes
+that you have built the libraries in ../libpng and ../zlib. Using Linux,
+make sure that you have built libpng with makefile.std and not
+makefile.linux (also called .lnx in earlier versions of libpng). The
+latter creates a .so shared-library, while the PngMinus makefile assumes
+a normal .a static library.
+
+If you create a ../pngsuite directory and then store the basn####.png
+files from PngSuite (http://www.schaik.com/pngsuite/) in there, you can
+test in one go the proper functioning of PngMinus, see png2pnm.bat and
+pnm2png.bat (or the .sh versions).
+
+
+Warranty
+-------
+Please, remember that this was just a small experiment to learn a few
+things. It will have many unforeseen features <vbg>. Who said bugs? Use
+it when you are in need for something simple or when you want to start
+developing your own stuff.
+
+
+The Turbo bug
+-------------
+** pngmem.old
+ hptr = (png_byte huge *)((long)(hptr) & 0xfffffff0L);
+ hptr += 16L;
+** pngmem.c
+ hptr = (png_byte huge *)((long)(hptr) & 0xfffffff0L);
+ hptr = hptr + 16L;
+**
+
+** pngmem.old
+ png_ptr->offset_table_ptr[i] = (png_bytep)hptr;
+ hptr += (png_uint_32)65536L;
+** pngmem.c
+ png_ptr->offset_table_ptr[i] = (png_bytep)hptr;
+ hptr = hptr + 65536L;
+**
+
+
+The end
+-------
+Willem van Schaik
+mailto:willem@schaik.com
+http://www.schaik.com/png/
+-------
+Oct 1999
+
diff --git a/libpng/contrib/pngminus/makefile.std b/libpng/contrib/pngminus/makefile.std
new file mode 100644
index 0000000..14e25cd
--- /dev/null
+++ b/libpng/contrib/pngminus/makefile.std
@@ -0,0 +1,66 @@
+# Makefile for PngMinus (png2pnm and pnm2png)
+# Linux / Unix
+
+#CC=cc
+CC=gcc
+LD=$(CC)
+
+RM=rm -f
+
+#PNGPATH = /usr/local
+#PNGINC = -I$(PNGPATH)/include/libpng16
+#PNGLIB = -L$(PNGPATH)/lib -lpng16
+#PNGLIBS = $(PNGPATH)/lib/libpng16.a
+PNGINC = -I../..
+PNGLIB = -L../.. -lpng
+PNGLIBS = ../../libpng.a
+
+#ZPATH = /usr/local
+#ZINC = -I$(ZPATH)/include
+#ZLIB = -L$(ZPATH)/lib -lz
+#ZLIBS = $(ZPATH)/lib/libz.a
+ZINC = -I../../../zlib
+ZLIB = -L../../../zlib -lz
+ZLIBS = ../../../zlib/libz.a
+
+CPPFLAGS=$(PNGINC) $(ZINC)
+CFLAGS=
+LDLIBS=$(PNGLIB) $(ZLIB)
+LDLIBSS=$(PNGLIBS) $(ZLIBS)
+C=.c
+O=.o
+L=.a
+E=
+
+# dependencies
+
+#all: png2pnm$(E) pnm2png$(E)
+all: png2pnm$(E) pnm2png$(E) png2pnm-static$(E) pnm2png-static$(E)
+
+png2pnm$(O): png2pnm$(C)
+ $(CC) -c $(CPPFLAGS) $(CFLAGS) png2pnm$(C)
+
+png2pnm$(E): png2pnm$(O)
+ $(LD) $(LDFLAGS) -o png2pnm$(E) png2pnm$(O) $(LDLIBS) -lm
+
+png2pnm-static$(E): png2pnm$(O)
+ $(LD) $(LDFLAGS) -o png2pnm-static$(E) png2pnm$(O) $(LDLIBSS) -lm
+
+pnm2png$(O): pnm2png$(C)
+ $(CC) -c $(CPPFLAGS) $(CFLAGS) pnm2png$(C)
+
+pnm2png$(E): pnm2png$(O)
+ $(LD) $(LDFLAGS) -o pnm2png$(E) pnm2png$(O) $(LDLIBS) -lm
+
+pnm2png-static$(E): pnm2png$(O)
+ $(LD) $(LDFLAGS) -o pnm2png-static$(E) pnm2png$(O) $(LDLIBSS) -lm
+
+clean:
+ $(RM) png2pnm$(O)
+ $(RM) pnm2png$(O)
+ $(RM) png2pnm$(E)
+ $(RM) pnm2png$(E)
+ $(RM) png2pnm-static$(E)
+ $(RM) pnm2png-static$(E)
+
+# End of makefile for png2pnm / pnm2png
diff --git a/libpng/contrib/pngminus/makefile.tc3 b/libpng/contrib/pngminus/makefile.tc3
new file mode 100644
index 0000000..6a2f4b9
--- /dev/null
+++ b/libpng/contrib/pngminus/makefile.tc3
@@ -0,0 +1,38 @@
+# Makefile for PngMinus (png2pnm and pnm2png)
+# TurboC++ 3.0
+
+CC=tcc -Ic:\tc3\inc
+LD=tcc -Lc:\tc3\lib
+LB=tlib
+RM=del
+CP=copy
+MODEL=l
+CPPFLAGS=-I..\libpng -I..\zlib
+CFLAGS=-O -m$(MODEL)
+LDFLAGS=-m$(MODEL) -L..\libpng -L..\zlib
+C=.c
+O=.obj
+L=.lib
+E=.exe
+
+# dependencies
+
+all: png2pnm$(E) pnm2png$(E)
+
+png2pnm$(O): png2pnm$(C)
+ $(CC) -c $(CPPFLAGS) $(CFLAGS) png2pnm$(C)
+
+png2pnm$(E): png2pnm$(O)
+ $(LD) $(LDFLAGS) png2pnm$(O) libpng$(L) zlib$(L)
+
+pnm2png$(O): pnm2png$(C)
+ $(CC) -c $(CPPFLAGS) $(CFLAGS) pnm2png$(C)
+
+pnm2png$(E): pnm2png$(O)
+ $(LD) $(LDFLAGS) pnm2png$(O) libpng$(L) zlib$(L)
+
+clean:
+ $(RM) *$(O)
+ $(RM) *$(E)
+
+# End of makefile for png2pnm / pnm2png
diff --git a/libpng/contrib/pngminus/makevms.com b/libpng/contrib/pngminus/makevms.com
new file mode 100644
index 0000000..00561bc
--- /dev/null
+++ b/libpng/contrib/pngminus/makevms.com
@@ -0,0 +1,92 @@
+$!------------------------------------------------------------------------------
+$! make Contrib programs of libpng under OpenVMS
+$!
+$!
+$! Look for the compiler used
+$!
+$ zlibsrc = "[---.zlib]"
+$ ccopt="/include=(''zlibsrc',[--])"
+$ if f$getsyi("HW_MODEL").ge.1024
+$ then
+$ ccopt = "/prefix=all"+ccopt
+$ comp = "__decc__=1"
+$ if f$trnlnm("SYS").eqs."" then define sys sys$library:
+$ else
+$ if f$search("SYS$SYSTEM:DECC$COMPILER.EXE").eqs.""
+$ then
+$ if f$trnlnm("SYS").eqs."" then define sys sys$library:
+$ if f$search("SYS$SYSTEM:VAXC.EXE").eqs.""
+$ then
+$ comp = "__gcc__=1"
+$ CC :== GCC
+$ else
+$ comp = "__vaxc__=1"
+$ endif
+$ else
+$ if f$trnlnm("SYS").eqs."" then define sys decc$library_include:
+$ ccopt = "/decc/prefix=all"+ccopt
+$ comp = "__decc__=1"
+$ endif
+$ endif
+$ open/write lopt lib.opt
+$ write lopt "[--]libpng.olb/lib"
+$ write lopt "''zlibsrc'libz.olb/lib"
+$ close lopt
+$ open/write xopt x11.opt
+$ write xopt "sys$library:decw$xlibshr.exe/share"
+$ close xopt
+$ write sys$output "Compiling PNG contrib programs ..."
+$ write sys$output "Building pnm2png..."
+$ CALL MAKE pnm2png.OBJ "cc ''CCOPT' pnm2png" -
+ pnm2png.c
+$ call make pnm2png.exe -
+ "LINK pnm2png,lib.opt/opt" -
+ pnm2png.obj
+$ write sys$output "Building png2pnm..."
+$ CALL MAKE png2pnm.OBJ "cc ''CCOPT' png2pnm" -
+ png2pnm.c
+$ call make png2pnm.exe -
+ "LINK png2pnm,lib.opt/opt" -
+ png2pnm.obj
+$ exit
+$!
+$!
+$MAKE: SUBROUTINE !SUBROUTINE TO CHECK DEPENDENCIES
+$ V = 'F$Verify(0)
+$! P1 = What we are trying to make
+$! P2 = Command to make it
+$! P3 - P8 What it depends on
+$
+$ If F$Search(P1) .Eqs. "" Then Goto Makeit
+$ Time = F$CvTime(F$File(P1,"RDT"))
+$arg=3
+$Loop:
+$ Argument = P'arg
+$ If Argument .Eqs. "" Then Goto Exit
+$ El=0
+$Loop2:
+$ File = F$Element(El," ",Argument)
+$ If File .Eqs. " " Then Goto Endl
+$ AFile = ""
+$Loop3:
+$ OFile = AFile
+$ AFile = F$Search(File)
+$ If AFile .Eqs. "" .Or. AFile .Eqs. OFile Then Goto NextEl
+$ If F$CvTime(F$File(AFile,"RDT")) .Ges. Time Then Goto Makeit
+$ Goto Loop3
+$NextEL:
+$ El = El + 1
+$ Goto Loop2
+$EndL:
+$ arg=arg+1
+$ If arg .Le. 8 Then Goto Loop
+$ Goto Exit
+$
+$Makeit:
+$ VV=F$VERIFY(0)
+$ write sys$output P2
+$ 'P2
+$ VV='F$Verify(VV)
+$Exit:
+$ If V Then Set Verify
+$ENDSUBROUTINE
diff --git a/libpng/contrib/pngminus/png2pnm.bat b/libpng/contrib/pngminus/png2pnm.bat
new file mode 100755
index 0000000..449cf36
--- /dev/null
+++ b/libpng/contrib/pngminus/png2pnm.bat
@@ -0,0 +1,41 @@
+REM -- grayscale
+png2pnm.exe -noraw ..\pngsuite\basn0g01.png basn0g01.pgm
+png2pnm.exe -noraw ..\pngsuite\basn0g02.png basn0g02.pgm
+png2pnm.exe -noraw ..\pngsuite\basn0g04.png basn0g04.pgm
+png2pnm.exe -noraw ..\pngsuite\basn0g08.png basn0g08.pgm
+png2pnm.exe -noraw ..\pngsuite\basn0g16.png basn0g16.pgm
+REM -- full-color
+png2pnm.exe -noraw ..\pngsuite\basn2c08.png basn2c08.ppm
+png2pnm.exe -noraw ..\pngsuite\basn2c16.png basn2c16.ppm
+REM -- palletted
+png2pnm.exe -noraw ..\pngsuite\basn3p01.png basn3p01.ppm
+png2pnm.exe -noraw ..\pngsuite\basn3p02.png basn3p02.ppm
+png2pnm.exe -noraw ..\pngsuite\basn3p04.png basn3p04.ppm
+png2pnm.exe -noraw ..\pngsuite\basn3p08.png basn3p08.ppm
+REM -- gray with alpha-channel
+png2pnm.exe -noraw ..\pngsuite\basn4a08.png basn4a08.pgm
+png2pnm.exe -noraw ..\pngsuite\basn4a16.png basn4a16.pgm
+REM -- color with alpha-channel
+png2pnm.exe -noraw -alpha basn6a08.pgm ..\pngsuite\basn6a08.png basn6a08.ppm
+png2pnm.exe -noraw -alpha basn6a16.pgm ..\pngsuite\basn6a16.png basn6a16.ppm
+REM -- grayscale
+png2pnm.exe -raw ..\pngsuite\basn0g01.png rawn0g01.pgm
+png2pnm.exe -raw ..\pngsuite\basn0g02.png rawn0g02.pgm
+png2pnm.exe -raw ..\pngsuite\basn0g04.png rawn0g04.pgm
+png2pnm.exe -raw ..\pngsuite\basn0g08.png rawn0g08.pgm
+png2pnm.exe -raw ..\pngsuite\basn0g16.png rawn0g16.pgm
+REM -- full-color
+png2pnm.exe -raw ..\pngsuite\basn2c08.png rawn2c08.ppm
+png2pnm.exe -raw ..\pngsuite\basn2c16.png rawn2c16.ppm
+REM -- palletted
+png2pnm.exe -raw ..\pngsuite\basn3p01.png rawn3p01.ppm
+png2pnm.exe -raw ..\pngsuite\basn3p02.png rawn3p02.ppm
+png2pnm.exe -raw ..\pngsuite\basn3p04.png rawn3p04.ppm
+png2pnm.exe -raw ..\pngsuite\basn3p08.png rawn3p08.ppm
+REM -- gray with alpha-channel
+png2pnm.exe -raw ..\pngsuite\basn4a08.png rawn4a08.pgm
+png2pnm.exe -raw ..\pngsuite\basn4a16.png rawn4a16.pgm
+REM -- color with alpha-channel
+png2pnm.exe -noraw -alpha rawn6a08.pgm ..\pngsuite\basn6a08.png rawn6a08.ppm
+png2pnm.exe -noraw -alpha rawn6a16.pgm ..\pngsuite\basn6a16.png rawn6a16.ppm
+
diff --git a/libpng/contrib/pngminus/png2pnm.c b/libpng/contrib/pngminus/png2pnm.c
new file mode 100644
index 0000000..f68d7ff
--- /dev/null
+++ b/libpng/contrib/pngminus/png2pnm.c
@@ -0,0 +1,438 @@
+/*
+ * png2pnm.c --- conversion from PNG-file to PGM/PPM-file
+ * copyright (C) 1999 by Willem van Schaik <willem@schaik.com>
+ *
+ * version 1.0 - 1999.10.15 - First version.
+ *
+ * Permission to use, copy, modify, and distribute this software and
+ * its documentation for any purpose and without fee is hereby granted,
+ * provided that the above copyright notice appear in all copies and
+ * that both that copyright notice and this permission notice appear in
+ * supporting documentation. This software is provided "as is" without
+ * express or implied warranty.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#ifdef __TURBOC__
+#include <mem.h>
+#include <fcntl.h>
+#endif
+#include <zlib.h>
+
+#ifndef BOOL
+#define BOOL unsigned char
+#endif
+#ifndef TRUE
+#define TRUE (BOOL) 1
+#endif
+#ifndef FALSE
+#define FALSE (BOOL) 0
+#endif
+
+#ifdef __TURBOC__
+#define STDIN 0
+#define STDOUT 1
+#define STDERR 2
+#endif
+
+/* to make png2pnm verbose so we can find problems (needs to be before png.h) */
+#ifndef PNG_DEBUG
+#define PNG_DEBUG 0
+#endif
+
+#include "png.h"
+
+/* Define png_jmpbuf() in case we are using a pre-1.0.6 version of libpng */
+#ifndef png_jmpbuf
+# define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
+#endif
+
+/* function prototypes */
+
+int main (int argc, char *argv[]);
+void usage ();
+BOOL png2pnm (FILE *png_file, FILE *pnm_file, FILE *alpha_file, BOOL raw,
+ BOOL alpha);
+
+/*
+ * main
+ */
+
+int main(int argc, char *argv[])
+{
+ FILE *fp_rd = stdin;
+ FILE *fp_wr = stdout;
+ FILE *fp_al = NULL;
+ BOOL raw = TRUE;
+ BOOL alpha = FALSE;
+ int argi;
+
+ for (argi = 1; argi < argc; argi++)
+ {
+ if (argv[argi][0] == '-')
+ {
+ switch (argv[argi][1])
+ {
+ case 'n':
+ raw = FALSE;
+ break;
+ case 'r':
+ raw = TRUE;
+ break;
+ case 'a':
+ alpha = TRUE;
+ argi++;
+ if ((fp_al = fopen (argv[argi], "wb")) == NULL)
+ {
+ fprintf (stderr, "PNM2PNG\n");
+ fprintf (stderr, "Error: can not create alpha-channel file %s\n",
+ argv[argi]);
+ exit (1);
+ }
+ break;
+ case 'h':
+ case '?':
+ usage();
+ exit(0);
+ break;
+ default:
+ fprintf (stderr, "PNG2PNM\n");
+ fprintf (stderr, "Error: unknown option %s\n", argv[argi]);
+ usage();
+ exit(1);
+ break;
+ } /* end switch */
+ }
+ else if (fp_rd == stdin)
+ {
+ if ((fp_rd = fopen (argv[argi], "rb")) == NULL)
+ {
+ fprintf (stderr, "PNG2PNM\n");
+ fprintf (stderr, "Error: file %s does not exist\n", argv[argi]);
+ exit (1);
+ }
+ }
+ else if (fp_wr == stdout)
+ {
+ if ((fp_wr = fopen (argv[argi], "wb")) == NULL)
+ {
+ fprintf (stderr, "PNG2PNM\n");
+ fprintf (stderr, "Error: can not create file %s\n", argv[argi]);
+ exit (1);
+ }
+ }
+ else
+ {
+ fprintf (stderr, "PNG2PNM\n");
+ fprintf (stderr, "Error: too many parameters\n");
+ usage();
+ exit(1);
+ }
+ } /* end for */
+
+#ifdef __TURBOC__
+ /* set stdin/stdout if required to binary */
+ if (fp_rd == stdin)
+ {
+ setmode (STDIN, O_BINARY);
+ }
+ if ((raw) && (fp_wr == stdout))
+ {
+ setmode (STDOUT, O_BINARY);
+ }
+#endif
+
+ /* call the conversion program itself */
+ if (png2pnm (fp_rd, fp_wr, fp_al, raw, alpha) == FALSE)
+ {
+ fprintf (stderr, "PNG2PNM\n");
+ fprintf (stderr, "Error: unsuccessful conversion of PNG-image\n");
+ exit(1);
+ }
+
+ /* close input file */
+ fclose (fp_rd);
+ /* close output file */
+ fclose (fp_wr);
+ /* close alpha file */
+ if (alpha)
+ fclose (fp_al);
+
+ return 0;
+}
+
+/*
+ * usage
+ */
+
+void usage()
+{
+ fprintf (stderr, "PNG2PNM\n");
+ fprintf (stderr, " by Willem van Schaik, 1999\n");
+#ifdef __TURBOC__
+ fprintf (stderr, " for Turbo-C and Borland-C compilers\n");
+#else
+ fprintf (stderr, " for Linux (and Unix) compilers\n");
+#endif
+ fprintf (stderr, "Usage: png2pnm [options] <file>.png [<file>.pnm]\n");
+ fprintf (stderr, " or: ... | png2pnm [options]\n");
+ fprintf (stderr, "Options:\n");
+ fprintf (stderr,
+ " -r[aw] write pnm-file in binary format (P4/P5/P6) (default)\n");
+ fprintf (stderr, " -n[oraw] write pnm-file in ascii format (P1/P2/P3)\n");
+ fprintf (stderr,
+ " -a[lpha] <file>.pgm write PNG alpha channel as pgm-file\n");
+ fprintf (stderr, " -h | -? print this help-information\n");
+}
+
+/*
+ * png2pnm
+ */
+
+BOOL png2pnm (FILE *png_file, FILE *pnm_file, FILE *alpha_file,
+ volatile BOOL raw, BOOL alpha)
+{
+ png_struct *png_ptr = NULL;
+ png_info *info_ptr = NULL;
+ png_byte buf[8];
+ png_byte *png_pixels = NULL;
+ png_byte **row_pointers = NULL;
+ png_byte *pix_ptr = NULL;
+ png_uint_32 row_bytes;
+
+ png_uint_32 width;
+ png_uint_32 height;
+ int bit_depth;
+ int channels;
+ int color_type;
+ int alpha_present;
+ int row, col;
+ int ret;
+ int i;
+ long dep_16;
+
+ /* read and check signature in PNG file */
+ ret = fread (buf, 1, 8, png_file);
+ if (ret != 8)
+ return FALSE;
+
+ ret = png_sig_cmp (buf, 0, 8);
+ if (ret)
+ return FALSE;
+
+ /* create png and info structures */
+
+ png_ptr = png_create_read_struct (png_get_libpng_ver(NULL),
+ NULL, NULL, NULL);
+ if (!png_ptr)
+ return FALSE; /* out of memory */
+
+ info_ptr = png_create_info_struct (png_ptr);
+ if (!info_ptr)
+ {
+ png_destroy_read_struct (&png_ptr, NULL, NULL);
+ return FALSE; /* out of memory */
+ }
+
+ if (setjmp (png_jmpbuf(png_ptr)))
+ {
+ png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
+ return FALSE;
+ }
+
+ /* set up the input control for C streams */
+ png_init_io (png_ptr, png_file);
+ png_set_sig_bytes (png_ptr, 8); /* we already read the 8 signature bytes */
+
+ /* read the file information */
+ png_read_info (png_ptr, info_ptr);
+
+ /* get size and bit-depth of the PNG-image */
+ png_get_IHDR (png_ptr, info_ptr,
+ &width, &height, &bit_depth, &color_type,
+ NULL, NULL, NULL);
+
+ /* set-up the transformations */
+
+ /* transform paletted images into full-color rgb */
+ if (color_type == PNG_COLOR_TYPE_PALETTE)
+ png_set_expand (png_ptr);
+ /* expand images to bit-depth 8 (only applicable for grayscale images) */
+ if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
+ png_set_expand (png_ptr);
+ /* transform transparency maps into full alpha-channel */
+ if (png_get_valid (png_ptr, info_ptr, PNG_INFO_tRNS))
+ png_set_expand (png_ptr);
+
+#ifdef NJET
+ /* downgrade 16-bit images to 8-bit */
+ if (bit_depth == 16)
+ png_set_strip_16 (png_ptr);
+ /* transform grayscale images into full-color */
+ if (color_type == PNG_COLOR_TYPE_GRAY ||
+ color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+ png_set_gray_to_rgb (png_ptr);
+ /* only if file has a file gamma, we do a correction */
+ if (png_get_gAMA (png_ptr, info_ptr, &file_gamma))
+ png_set_gamma (png_ptr, (double) 2.2, file_gamma);
+#endif
+
+ /* all transformations have been registered; now update info_ptr data,
+ * get rowbytes and channels, and allocate image memory */
+
+ png_read_update_info (png_ptr, info_ptr);
+
+ /* get the new color-type and bit-depth (after expansion/stripping) */
+ png_get_IHDR (png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
+ NULL, NULL, NULL);
+
+ /* check for 16-bit files */
+ if (bit_depth == 16)
+ {
+ raw = FALSE;
+#ifdef __TURBOC__
+ pnm_file->flags &= ~((unsigned) _F_BIN);
+#endif
+ }
+
+ /* calculate new number of channels and store alpha-presence */
+ if (color_type == PNG_COLOR_TYPE_GRAY)
+ channels = 1;
+ else if (color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+ channels = 2;
+ else if (color_type == PNG_COLOR_TYPE_RGB)
+ channels = 3;
+ else if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+ channels = 4;
+ else
+ channels = 0; /* should never happen */
+ alpha_present = (channels - 1) % 2;
+
+ /* check if alpha is expected to be present in file */
+ if (alpha && !alpha_present)
+ {
+ fprintf (stderr, "PNG2PNM\n");
+ fprintf (stderr, "Error: PNG-file doesn't contain alpha channel\n");
+ exit (1);
+ }
+
+ /* row_bytes is the width x number of channels x (bit-depth / 8) */
+ row_bytes = png_get_rowbytes (png_ptr, info_ptr);
+
+ if ((png_pixels = (png_byte *)
+ malloc (row_bytes * height * sizeof (png_byte))) == NULL) {
+ png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
+ return FALSE;
+ }
+
+ if ((row_pointers = (png_byte **)
+ malloc (height * sizeof (png_bytep))) == NULL)
+ {
+ png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
+ free (png_pixels);
+ png_pixels = NULL;
+ return FALSE;
+ }
+
+ /* set the individual row_pointers to point at the correct offsets */
+ for (i = 0; i < ((int) height); i++)
+ row_pointers[i] = png_pixels + i * row_bytes;
+
+ /* now we can go ahead and just read the whole image */
+ png_read_image (png_ptr, row_pointers);
+
+ /* read rest of file, and get additional chunks in info_ptr - REQUIRED */
+ png_read_end (png_ptr, info_ptr);
+
+ /* clean up after the read, and free any memory allocated - REQUIRED */
+ png_destroy_read_struct (&png_ptr, &info_ptr, (png_infopp) NULL);
+
+ /* write header of PNM file */
+
+ if ((color_type == PNG_COLOR_TYPE_GRAY) ||
+ (color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
+ {
+ fprintf (pnm_file, "%s\n", (raw) ? "P5" : "P2");
+ fprintf (pnm_file, "%d %d\n", (int) width, (int) height);
+ fprintf (pnm_file, "%ld\n", ((1L << (int) bit_depth) - 1L));
+ }
+ else if ((color_type == PNG_COLOR_TYPE_RGB) ||
+ (color_type == PNG_COLOR_TYPE_RGB_ALPHA))
+ {
+ fprintf (pnm_file, "%s\n", (raw) ? "P6" : "P3");
+ fprintf (pnm_file, "%d %d\n", (int) width, (int) height);
+ fprintf (pnm_file, "%ld\n", ((1L << (int) bit_depth) - 1L));
+ }
+
+ /* write header of PGM file with alpha channel */
+
+ if ((alpha) &&
+ ((color_type == PNG_COLOR_TYPE_GRAY_ALPHA) ||
+ (color_type == PNG_COLOR_TYPE_RGB_ALPHA)))
+ {
+ fprintf (alpha_file, "%s\n", (raw) ? "P5" : "P2");
+ fprintf (alpha_file, "%d %d\n", (int) width, (int) height);
+ fprintf (alpha_file, "%ld\n", ((1L << (int) bit_depth) - 1L));
+ }
+
+ /* write data to PNM file */
+ pix_ptr = png_pixels;
+
+ for (row = 0; row < (int) height; row++)
+ {
+ for (col = 0; col < (int) width; col++)
+ {
+ for (i = 0; i < (channels - alpha_present); i++)
+ {
+ if (raw)
+ fputc ((int) *pix_ptr++ , pnm_file);
+ else
+ if (bit_depth == 16){
+ dep_16 = (long) *pix_ptr++;
+ fprintf (pnm_file, "%ld ", (dep_16 << 8) + ((long) *pix_ptr++));
+ }
+ else
+ fprintf (pnm_file, "%ld ", (long) *pix_ptr++);
+ }
+ if (alpha_present)
+ {
+ if (!alpha)
+ {
+ pix_ptr++; /* alpha */
+ if (bit_depth == 16)
+ pix_ptr++;
+ }
+ else /* output alpha-channel as pgm file */
+ {
+ if (raw)
+ fputc ((int) *pix_ptr++ , alpha_file);
+ else
+ if (bit_depth == 16){
+ dep_16 = (long) *pix_ptr++;
+ fprintf (alpha_file, "%ld ", (dep_16 << 8) + (long) *pix_ptr++);
+ }
+ else
+ fprintf (alpha_file, "%ld ", (long) *pix_ptr++);
+ }
+ } /* if alpha_present */
+
+ if (!raw)
+ if (col % 4 == 3)
+ fprintf (pnm_file, "\n");
+ } /* end for col */
+
+ if (!raw)
+ if (col % 4 != 0)
+ fprintf (pnm_file, "\n");
+ } /* end for row */
+
+ if (row_pointers != (unsigned char**) NULL)
+ free (row_pointers);
+ if (png_pixels != (unsigned char*) NULL)
+ free (png_pixels);
+
+ return TRUE;
+
+} /* end of source */
+
diff --git a/libpng/contrib/pngminus/png2pnm.sh b/libpng/contrib/pngminus/png2pnm.sh
new file mode 100755
index 0000000..b1c0537
--- /dev/null
+++ b/libpng/contrib/pngminus/png2pnm.sh
@@ -0,0 +1,42 @@
+#!/bin/sh
+# -- grayscale
+./png2pnm -noraw ../pngsuite/basn0g01.png basn0g01.pgm
+./png2pnm -noraw ../pngsuite/basn0g02.png basn0g02.pgm
+./png2pnm -noraw ../pngsuite/basn0g04.png basn0g04.pgm
+./png2pnm -noraw ../pngsuite/basn0g08.png basn0g08.pgm
+./png2pnm -noraw ../pngsuite/basn0g16.png basn0g16.pgm
+# -- full-color
+./png2pnm -noraw ../pngsuite/basn2c08.png basn2c08.ppm
+./png2pnm -noraw ../pngsuite/basn2c16.png basn2c16.ppm
+# -- palletted
+./png2pnm -noraw ../pngsuite/basn3p01.png basn3p01.ppm
+./png2pnm -noraw ../pngsuite/basn3p02.png basn3p02.ppm
+./png2pnm -noraw ../pngsuite/basn3p04.png basn3p04.ppm
+./png2pnm -noraw ../pngsuite/basn3p08.png basn3p08.ppm
+# -- gray with alpha-channel
+./png2pnm -noraw ../pngsuite/basn4a08.png basn4a08.pgm
+./png2pnm -noraw ../pngsuite/basn4a16.png basn4a16.pgm
+# -- color with alpha-channel
+./png2pnm -noraw -alpha basn6a08.pgm ../pngsuite/basn6a08.png basn6a08.ppm
+./png2pnm -noraw -alpha basn6a16.pgm ../pngsuite/basn6a16.png basn6a16.ppm
+# -- grayscale
+./png2pnm -raw ../pngsuite/basn0g01.png rawn0g01.pgm
+./png2pnm -raw ../pngsuite/basn0g02.png rawn0g02.pgm
+./png2pnm -raw ../pngsuite/basn0g04.png rawn0g04.pgm
+./png2pnm -raw ../pngsuite/basn0g08.png rawn0g08.pgm
+./png2pnm -raw ../pngsuite/basn0g16.png rawn0g16.pgm
+# -- full-color
+./png2pnm -raw ../pngsuite/basn2c08.png rawn2c08.ppm
+./png2pnm -raw ../pngsuite/basn2c16.png rawn2c16.ppm
+# -- palletted
+./png2pnm -raw ../pngsuite/basn3p01.png rawn3p01.ppm
+./png2pnm -raw ../pngsuite/basn3p02.png rawn3p02.ppm
+./png2pnm -raw ../pngsuite/basn3p04.png rawn3p04.ppm
+./png2pnm -raw ../pngsuite/basn3p08.png rawn3p08.ppm
+# -- gray with alpha-channel
+./png2pnm -raw ../pngsuite/basn4a08.png rawn4a08.pgm
+./png2pnm -raw ../pngsuite/basn4a16.png rawn4a16.pgm
+# -- color with alpha-channel
+./png2pnm -noraw -alpha rawn6a08.pgm ../pngsuite/basn6a08.png rawn6a08.ppm
+./png2pnm -noraw -alpha rawn6a16.pgm ../pngsuite/basn6a16.png rawn6a16.ppm
+
diff --git a/libpng/contrib/pngminus/pngminus.bat b/libpng/contrib/pngminus/pngminus.bat
new file mode 100755
index 0000000..911bb8d
--- /dev/null
+++ b/libpng/contrib/pngminus/pngminus.bat
@@ -0,0 +1,4 @@
+make -f makefile.tc3
+call png2pnm.bat
+call pnm2png.bat
+
diff --git a/libpng/contrib/pngminus/pngminus.sh b/libpng/contrib/pngminus/pngminus.sh
new file mode 100755
index 0000000..2a0a9d8
--- /dev/null
+++ b/libpng/contrib/pngminus/pngminus.sh
@@ -0,0 +1,5 @@
+#!/bin/sh
+make -f makefile.std
+sh png2pnm.sh
+sh pnm2png.sh
+
diff --git a/libpng/contrib/pngminus/pnm2png.bat b/libpng/contrib/pngminus/pnm2png.bat
new file mode 100755
index 0000000..f756cb8
--- /dev/null
+++ b/libpng/contrib/pngminus/pnm2png.bat
@@ -0,0 +1,41 @@
+REM -- grayscale
+pnm2png.exe basn0g01.pgm basn0g01.png
+pnm2png.exe basn0g02.pgm basn0g02.png
+pnm2png.exe basn0g04.pgm basn0g04.png
+pnm2png.exe basn0g08.pgm basn0g08.png
+pnm2png.exe basn0g16.pgm basn0g16.png
+REM -- full-color
+pnm2png.exe basn2c08.ppm basn2c08.png
+pnm2png.exe basn2c16.ppm basn2c16.png
+REM -- palletted
+pnm2png.exe basn3p01.ppm basn3p01.png
+pnm2png.exe basn3p02.ppm basn3p02.png
+pnm2png.exe basn3p04.ppm basn3p04.png
+pnm2png.exe basn3p08.ppm basn3p08.png
+REM -- gray with alpha-channel
+pnm2png.exe -alpha basn6a08.pgm basn4a08.pgm basn4a08.png
+pnm2png.exe -alpha basn6a16.pgm basn4a16.pgm basn4a16.png
+REM -- color with alpha-channel
+pnm2png.exe -alpha basn6a08.pgm basn6a08.ppm basn6a08.png
+pnm2png.exe -alpha basn6a16.pgm basn6a16.ppm basn6a16.png
+REM -- grayscale
+pnm2png.exe rawn0g01.pgm rawn0g01.png
+pnm2png.exe rawn0g02.pgm rawn0g02.png
+pnm2png.exe rawn0g04.pgm rawn0g04.png
+pnm2png.exe rawn0g08.pgm rawn0g08.png
+pnm2png.exe rawn0g16.pgm rawn0g16.png
+REM -- full-color
+pnm2png.exe rawn2c08.ppm rawn2c08.png
+pnm2png.exe rawn2c16.ppm rawn2c16.png
+REM -- palletted
+pnm2png.exe rawn3p01.ppm rawn3p01.png
+pnm2png.exe rawn3p02.ppm rawn3p02.png
+pnm2png.exe rawn3p04.ppm rawn3p04.png
+pnm2png.exe rawn3p08.ppm rawn3p08.png
+REM -- gray with alpha-channel
+pnm2png.exe -alpha rawn6a08.pgm rawn4a08.pgm rawn4a08.png
+pnm2png.exe -alpha rawn6a16.pgm rawn4a16.pgm rawn4a16.png
+REM -- color with alpha-channel
+pnm2png.exe -alpha rawn6a08.pgm rawn6a08.ppm rawn6a08.png
+pnm2png.exe -alpha rawn6a16.pgm rawn6a16.ppm rawn6a16.png
+
diff --git a/libpng/contrib/pngminus/pnm2png.c b/libpng/contrib/pngminus/pnm2png.c
new file mode 100644
index 0000000..8fa64cd
--- /dev/null
+++ b/libpng/contrib/pngminus/pnm2png.c
@@ -0,0 +1,616 @@
+/*
+ * pnm2png.c --- conversion from PBM/PGM/PPM-file to PNG-file
+ * copyright (C) 1999 by Willem van Schaik <willem@schaik.com>
+ *
+ * version 1.0 - 1999.10.15 - First version.
+ * version 1.1 - 2015.07.29 - Fixed leaks (Glenn Randers-Pehrson)
+ *
+ * Permission to use, copy, modify, and distribute this software and
+ * its documentation for any purpose and without fee is hereby granted,
+ * provided that the above copyright notice appear in all copies and
+ * that both that copyright notice and this permission notice appear in
+ * supporting documentation. This software is provided "as is" without
+ * express or implied warranty.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#ifdef __TURBOC__
+#include <mem.h>
+#include <fcntl.h>
+#endif
+#include <zlib.h>
+
+#ifndef BOOL
+#define BOOL unsigned char
+#endif
+#ifndef TRUE
+#define TRUE (BOOL) 1
+#endif
+#ifndef FALSE
+#define FALSE (BOOL) 0
+#endif
+
+#define STDIN 0
+#define STDOUT 1
+#define STDERR 2
+
+/* to make pnm2png verbose so we can find problems (needs to be before png.h) */
+#ifndef PNG_DEBUG
+#define PNG_DEBUG 0
+#endif
+
+#include "png.h"
+
+/* Define png_jmpbuf() in case we are using a pre-1.0.6 version of libpng */
+#ifndef png_jmpbuf
+# define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
+#endif
+
+/* function prototypes */
+
+int main (int argc, char *argv[]);
+void usage ();
+BOOL pnm2png (FILE *pnm_file, FILE *png_file, FILE *alpha_file, BOOL interlace,
+ BOOL alpha);
+void get_token(FILE *pnm_file, char *token);
+png_uint_32 get_data (FILE *pnm_file, int depth);
+png_uint_32 get_value (FILE *pnm_file, int depth);
+
+/*
+ * main
+ */
+
+int main(int argc, char *argv[])
+{
+ FILE *fp_rd = stdin;
+ FILE *fp_al = NULL;
+ FILE *fp_wr = stdout;
+ BOOL interlace = FALSE;
+ BOOL alpha = FALSE;
+ int argi;
+
+ for (argi = 1; argi < argc; argi++)
+ {
+ if (argv[argi][0] == '-')
+ {
+ switch (argv[argi][1])
+ {
+ case 'i':
+ interlace = TRUE;
+ break;
+ case 'a':
+ alpha = TRUE;
+ argi++;
+ if ((fp_al = fopen (argv[argi], "rb")) == NULL)
+ {
+ fprintf (stderr, "PNM2PNG\n");
+ fprintf (stderr, "Error: alpha-channel file %s does not exist\n",
+ argv[argi]);
+ exit (1);
+ }
+ break;
+ case 'h':
+ case '?':
+ usage();
+ exit(0);
+ break;
+ default:
+ fprintf (stderr, "PNM2PNG\n");
+ fprintf (stderr, "Error: unknown option %s\n", argv[argi]);
+ usage();
+ exit(1);
+ break;
+ } /* end switch */
+ }
+ else if (fp_rd == stdin)
+ {
+ if ((fp_rd = fopen (argv[argi], "rb")) == NULL)
+ {
+ fprintf (stderr, "PNM2PNG\n");
+ fprintf (stderr, "Error: file %s does not exist\n", argv[argi]);
+ exit (1);
+ }
+ }
+ else if (fp_wr == stdout)
+ {
+ if ((fp_wr = fopen (argv[argi], "wb")) == NULL)
+ {
+ fprintf (stderr, "PNM2PNG\n");
+ fprintf (stderr, "Error: can not create PNG-file %s\n", argv[argi]);
+ exit (1);
+ }
+ }
+ else
+ {
+ fprintf (stderr, "PNM2PNG\n");
+ fprintf (stderr, "Error: too many parameters\n");
+ usage();
+ exit (1);
+ }
+ } /* end for */
+
+#ifdef __TURBOC__
+ /* set stdin/stdout to binary, we're reading the PNM always! in binary format */
+ if (fp_rd == stdin)
+ {
+ setmode (STDIN, O_BINARY);
+ }
+ if (fp_wr == stdout)
+ {
+ setmode (STDOUT, O_BINARY);
+ }
+#endif
+
+ /* call the conversion program itself */
+ if (pnm2png (fp_rd, fp_wr, fp_al, interlace, alpha) == FALSE)
+ {
+ fprintf (stderr, "PNM2PNG\n");
+ fprintf (stderr, "Error: unsuccessful converting to PNG-image\n");
+ exit (1);
+ }
+
+ /* close input file */
+ fclose (fp_rd);
+ /* close output file */
+ fclose (fp_wr);
+ /* close alpha file */
+ if (alpha)
+ fclose (fp_al);
+
+ return 0;
+}
+
+/*
+ * usage
+ */
+
+void usage()
+{
+ fprintf (stderr, "PNM2PNG\n");
+ fprintf (stderr, " by Willem van Schaik, 1999\n");
+#ifdef __TURBOC__
+ fprintf (stderr, " for Turbo-C and Borland-C compilers\n");
+#else
+ fprintf (stderr, " for Linux (and Unix) compilers\n");
+#endif
+ fprintf (stderr, "Usage: pnm2png [options] <file>.<pnm> [<file>.png]\n");
+ fprintf (stderr, " or: ... | pnm2png [options]\n");
+ fprintf (stderr, "Options:\n");
+ fprintf (stderr, " -i[nterlace] write png-file with interlacing on\n");
+ fprintf (stderr,
+ " -a[lpha] <file>.pgm read PNG alpha channel as pgm-file\n");
+ fprintf (stderr, " -h | -? print this help-information\n");
+}
+
+/*
+ * pnm2png
+ */
+
+BOOL pnm2png (FILE *pnm_file, FILE *png_file, FILE *alpha_file, BOOL interlace,
+ BOOL alpha)
+{
+ png_struct *png_ptr = NULL;
+ png_info *info_ptr = NULL;
+ png_byte *png_pixels = NULL;
+ png_byte **row_pointers = NULL;
+ png_byte *pix_ptr = NULL;
+ volatile png_uint_32 row_bytes;
+
+ char type_token[16];
+ char width_token[16];
+ char height_token[16];
+ char maxval_token[16];
+ volatile int color_type=1;
+ unsigned long ul_width=0, ul_alpha_width=0;
+ unsigned long ul_height=0, ul_alpha_height=0;
+ unsigned long ul_maxval=0;
+ volatile png_uint_32 width=0, height=0;
+ volatile png_uint_32 alpha_width=0, alpha_height=0;
+ png_uint_32 maxval;
+ volatile int bit_depth = 0;
+ int channels=0;
+ int alpha_depth = 0;
+ int alpha_present=0;
+ int row, col;
+ BOOL raw, alpha_raw = FALSE;
+#if defined(PNG_WRITE_INVERT_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
+ BOOL packed_bitmap = FALSE;
+#endif
+ png_uint_32 tmp16;
+ int i;
+
+ /* read header of PNM file */
+
+ get_token(pnm_file, type_token);
+ if (type_token[0] != 'P')
+ {
+ return FALSE;
+ }
+ else if ((type_token[1] == '1') || (type_token[1] == '4'))
+ {
+#if defined(PNG_WRITE_INVERT_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
+ raw = (type_token[1] == '4');
+ color_type = PNG_COLOR_TYPE_GRAY;
+ get_token(pnm_file, width_token);
+ sscanf (width_token, "%lu", &ul_width);
+ width = (png_uint_32) ul_width;
+ get_token(pnm_file, height_token);
+ sscanf (height_token, "%lu", &ul_height);
+ height = (png_uint_32) ul_height;
+ bit_depth = 1;
+ packed_bitmap = TRUE;
+#else
+ fprintf (stderr, "PNM2PNG built without PNG_WRITE_INVERT_SUPPORTED and \n");
+ fprintf (stderr, "PNG_WRITE_PACK_SUPPORTED can't read PBM (P1,P4) files\n");
+#endif
+ }
+ else if ((type_token[1] == '2') || (type_token[1] == '5'))
+ {
+ raw = (type_token[1] == '5');
+ color_type = PNG_COLOR_TYPE_GRAY;
+ get_token(pnm_file, width_token);
+ sscanf (width_token, "%lu", &ul_width);
+ width = (png_uint_32) ul_width;
+ get_token(pnm_file, height_token);
+ sscanf (height_token, "%lu", &ul_height);
+ height = (png_uint_32) ul_height;
+ get_token(pnm_file, maxval_token);
+ sscanf (maxval_token, "%lu", &ul_maxval);
+ maxval = (png_uint_32) ul_maxval;
+
+ if (maxval <= 1)
+ bit_depth = 1;
+ else if (maxval <= 3)
+ bit_depth = 2;
+ else if (maxval <= 15)
+ bit_depth = 4;
+ else if (maxval <= 255)
+ bit_depth = 8;
+ else /* if (maxval <= 65535) */
+ bit_depth = 16;
+ }
+ else if ((type_token[1] == '3') || (type_token[1] == '6'))
+ {
+ raw = (type_token[1] == '6');
+ color_type = PNG_COLOR_TYPE_RGB;
+ get_token(pnm_file, width_token);
+ sscanf (width_token, "%lu", &ul_width);
+ width = (png_uint_32) ul_width;
+ get_token(pnm_file, height_token);
+ sscanf (height_token, "%lu", &ul_height);
+ height = (png_uint_32) ul_height;
+ get_token(pnm_file, maxval_token);
+ sscanf (maxval_token, "%lu", &ul_maxval);
+ maxval = (png_uint_32) ul_maxval;
+ if (maxval <= 1)
+ bit_depth = 1;
+ else if (maxval <= 3)
+ bit_depth = 2;
+ else if (maxval <= 15)
+ bit_depth = 4;
+ else if (maxval <= 255)
+ bit_depth = 8;
+ else /* if (maxval <= 65535) */
+ bit_depth = 16;
+ }
+ else
+ {
+ return FALSE;
+ }
+
+ /* read header of PGM file with alpha channel */
+
+ if (alpha)
+ {
+ if (color_type == PNG_COLOR_TYPE_GRAY)
+ color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
+ if (color_type == PNG_COLOR_TYPE_RGB)
+ color_type = PNG_COLOR_TYPE_RGB_ALPHA;
+
+ get_token(alpha_file, type_token);
+ if (type_token[0] != 'P')
+ {
+ return FALSE;
+ }
+ else if ((type_token[1] == '2') || (type_token[1] == '5'))
+ {
+ alpha_raw = (type_token[1] == '5');
+ get_token(alpha_file, width_token);
+ sscanf (width_token, "%lu", &ul_alpha_width);
+ alpha_width=(png_uint_32) ul_alpha_width;
+ if (alpha_width != width)
+ return FALSE;
+ get_token(alpha_file, height_token);
+ sscanf (height_token, "%lu", &ul_alpha_height);
+ alpha_height = (png_uint_32) ul_alpha_height;
+ if (alpha_height != height)
+ return FALSE;
+ get_token(alpha_file, maxval_token);
+ sscanf (maxval_token, "%lu", &ul_maxval);
+ maxval = (png_uint_32) ul_maxval;
+ if (maxval <= 1)
+ alpha_depth = 1;
+ else if (maxval <= 3)
+ alpha_depth = 2;
+ else if (maxval <= 15)
+ alpha_depth = 4;
+ else if (maxval <= 255)
+ alpha_depth = 8;
+ else /* if (maxval <= 65535) */
+ alpha_depth = 16;
+ if (alpha_depth != bit_depth)
+ return FALSE;
+ }
+ else
+ {
+ return FALSE;
+ }
+ } /* end if alpha */
+
+ /* calculate the number of channels and store alpha-presence */
+ if (color_type == PNG_COLOR_TYPE_GRAY)
+ channels = 1;
+ else if (color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+ channels = 2;
+ else if (color_type == PNG_COLOR_TYPE_RGB)
+ channels = 3;
+ else if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+ channels = 4;
+#if 0
+ else
+ channels = 0; /* cannot happen */
+#endif
+
+ alpha_present = (channels - 1) % 2;
+
+#if defined(PNG_WRITE_INVERT_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
+ if (packed_bitmap)
+ /* row data is as many bytes as can fit width x channels x bit_depth */
+ row_bytes = (width * channels * bit_depth + 7) / 8;
+ else
+#endif
+ /* row_bytes is the width x number of channels x (bit-depth / 8) */
+ row_bytes = width * channels * ((bit_depth <= 8) ? 1 : 2);
+
+ if ((png_pixels = (png_byte *)
+ malloc (row_bytes * height * sizeof (png_byte))) == NULL)
+ return FALSE;
+
+ /* read data from PNM file */
+ pix_ptr = png_pixels;
+
+ for (row = 0; row < (int) height; row++)
+ {
+#if defined(PNG_WRITE_INVERT_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
+ if (packed_bitmap) {
+ for (i = 0; i < (int) row_bytes; i++)
+ /* png supports this format natively so no conversion is needed */
+ *pix_ptr++ = get_data (pnm_file, 8);
+ } else
+#endif
+ {
+ for (col = 0; col < (int) width; col++)
+ {
+ for (i = 0; i < (channels - alpha_present); i++)
+ {
+ if (raw)
+ *pix_ptr++ = get_data (pnm_file, bit_depth);
+ else
+ if (bit_depth <= 8)
+ *pix_ptr++ = get_value (pnm_file, bit_depth);
+ else
+ {
+ tmp16 = get_value (pnm_file, bit_depth);
+ *pix_ptr = (png_byte) ((tmp16 >> 8) & 0xFF);
+ pix_ptr++;
+ *pix_ptr = (png_byte) (tmp16 & 0xFF);
+ pix_ptr++;
+ }
+ }
+
+ if (alpha) /* read alpha-channel from pgm file */
+ {
+ if (alpha_raw)
+ *pix_ptr++ = get_data (alpha_file, alpha_depth);
+ else
+ if (alpha_depth <= 8)
+ *pix_ptr++ = get_value (alpha_file, bit_depth);
+ else
+ {
+ tmp16 = get_value (alpha_file, bit_depth);
+ *pix_ptr++ = (png_byte) ((tmp16 >> 8) & 0xFF);
+ *pix_ptr++ = (png_byte) (tmp16 & 0xFF);
+ }
+ } /* if alpha */
+ } /* if packed_bitmap */
+ } /* end for col */
+ } /* end for row */
+
+ /* prepare the standard PNG structures */
+ png_ptr = png_create_write_struct (png_get_libpng_ver(NULL), NULL, NULL,
+ NULL);
+ if (!png_ptr)
+ {
+ free (png_pixels);
+ png_pixels = NULL;
+ return FALSE;
+ }
+ info_ptr = png_create_info_struct (png_ptr);
+ if (!info_ptr)
+ {
+ png_destroy_write_struct (&png_ptr, (png_infopp) NULL);
+ free (png_pixels);
+ png_pixels = NULL;
+ return FALSE;
+ }
+
+#if defined(PNG_WRITE_INVERT_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
+ if (packed_bitmap == TRUE)
+ {
+ png_set_packing (png_ptr);
+ png_set_invert_mono (png_ptr);
+ }
+#endif
+
+ /* setjmp() must be called in every function that calls a PNG-reading libpng function */
+ if (setjmp (png_jmpbuf(png_ptr)))
+ {
+ png_destroy_write_struct (&png_ptr, &info_ptr);
+ free (png_pixels);
+ png_pixels = NULL;
+ return FALSE;
+ }
+
+ /* initialize the png structure */
+ png_init_io (png_ptr, png_file);
+
+ /* we're going to write more or less the same PNG as the input file */
+ png_set_IHDR (png_ptr, info_ptr, width, height, bit_depth, color_type,
+ (!interlace) ? PNG_INTERLACE_NONE : PNG_INTERLACE_ADAM7,
+ PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+
+ /* write the file header information */
+ png_write_info (png_ptr, info_ptr);
+
+ /* if needed we will allocate memory for an new array of row-pointers */
+ if (row_pointers == (unsigned char**) NULL)
+ {
+ if ((row_pointers = (png_byte **)
+ malloc (height * sizeof (png_bytep))) == NULL)
+ {
+ png_destroy_write_struct (&png_ptr, &info_ptr);
+ free (png_pixels);
+ png_pixels = NULL;
+ return FALSE;
+ }
+ }
+
+ /* set the individual row_pointers to point at the correct offsets */
+ for (i = 0; i < (int) height; i++)
+ row_pointers[i] = png_pixels + i * row_bytes;
+
+ /* write out the entire image data in one call */
+ png_write_image (png_ptr, row_pointers);
+
+ /* write the additional chunks to the PNG file (not really needed) */
+ png_write_end (png_ptr, info_ptr);
+
+ /* clean up after the write, and free any memory allocated */
+ png_destroy_write_struct (&png_ptr, &info_ptr);
+
+ if (row_pointers != (unsigned char**) NULL)
+ free (row_pointers);
+ if (png_pixels != (unsigned char*) NULL)
+ free (png_pixels);
+
+ return TRUE;
+} /* end of pnm2png */
+
+/*
+ * get_token() - gets the first string after whitespace
+ */
+
+void get_token(FILE *pnm_file, char *token)
+{
+ int i = 0;
+ int ret;
+
+ /* remove white-space and comment lines */
+ do
+ {
+ ret = fgetc(pnm_file);
+ if (ret == '#') {
+ /* the rest of this line is a comment */
+ do
+ {
+ ret = fgetc(pnm_file);
+ }
+ while ((ret != '\n') && (ret != '\r') && (ret != EOF));
+ }
+ if (ret == EOF) break;
+ token[i] = (unsigned char) ret;
+ }
+ while ((token[i] == '\n') || (token[i] == '\r') || (token[i] == ' '));
+
+ /* read string */
+ do
+ {
+ ret = fgetc(pnm_file);
+ if (ret == EOF) break;
+ i++;
+ token[i] = (unsigned char) ret;
+ }
+ while ((token[i] != '\n') && (token[i] != '\r') && (token[i] != ' '));
+
+ token[i] = '\0';
+
+ return;
+}
+
+/*
+ * get_data() - takes first byte and converts into next pixel value,
+ * taking as much bits as defined by bit-depth and
+ * using the bit-depth to fill up a byte (0Ah -> AAh)
+ */
+
+png_uint_32 get_data (FILE *pnm_file, int depth)
+{
+ static int bits_left = 0;
+ static int old_value = 0;
+ static int mask = 0;
+ int i;
+ png_uint_32 ret_value;
+
+ if (mask == 0)
+ for (i = 0; i < depth; i++)
+ mask = (mask >> 1) | 0x80;
+
+ if (bits_left <= 0)
+ {
+ old_value = fgetc (pnm_file);
+ bits_left = 8;
+ }
+
+ ret_value = old_value & mask;
+ for (i = 1; i < (8 / depth); i++)
+ ret_value = ret_value || (ret_value >> depth);
+
+ old_value = (old_value << depth) & 0xFF;
+ bits_left -= depth;
+
+ return ret_value;
+}
+
+/*
+ * get_value() - takes first (numeric) string and converts into number,
+ * using the bit-depth to fill up a byte (0Ah -> AAh)
+ */
+
+png_uint_32 get_value (FILE *pnm_file, int depth)
+{
+ static png_uint_32 mask = 0;
+ png_byte token[16];
+ unsigned long ul_ret_value;
+ png_uint_32 ret_value;
+ int i = 0;
+
+ if (mask == 0)
+ for (i = 0; i < depth; i++)
+ mask = (mask << 1) | 0x01;
+
+ get_token (pnm_file, (char *) token);
+ sscanf ((const char *) token, "%lu", &ul_ret_value);
+ ret_value = (png_uint_32) ul_ret_value;
+
+ ret_value &= mask;
+
+ if (depth < 8)
+ for (i = 0; i < (8 / depth); i++)
+ ret_value = (ret_value << depth) || ret_value;
+
+ return ret_value;
+}
+
+/* end of source */
+
diff --git a/libpng/contrib/pngminus/pnm2png.sh b/libpng/contrib/pngminus/pnm2png.sh
new file mode 100755
index 0000000..d79df2f
--- /dev/null
+++ b/libpng/contrib/pngminus/pnm2png.sh
@@ -0,0 +1,42 @@
+#!/bin/sh
+# -- grayscale
+./pnm2png basn0g01.pgm basn0g01.png
+./pnm2png basn0g02.pgm basn0g02.png
+./pnm2png basn0g04.pgm basn0g04.png
+./pnm2png basn0g08.pgm basn0g08.png
+./pnm2png basn0g16.pgm basn0g16.png
+# -- full-color
+./pnm2png basn2c08.ppm basn2c08.png
+./pnm2png basn2c16.ppm basn2c16.png
+# -- palletted
+./pnm2png basn3p01.ppm basn3p01.png
+./pnm2png basn3p02.ppm basn3p02.png
+./pnm2png basn3p04.ppm basn3p04.png
+./pnm2png basn3p08.ppm basn3p08.png
+# -- gray with alpha-channel
+./pnm2png -alpha basn6a08.pgm basn4a08.pgm basn4a08.png
+./pnm2png -alpha basn6a16.pgm basn4a16.pgm basn4a16.png
+# -- color with alpha-channel
+./pnm2png -alpha basn6a08.pgm basn6a08.ppm basn6a08.png
+./pnm2png -alpha basn6a16.pgm basn6a16.ppm basn6a16.png
+# -- grayscale
+./pnm2png rawn0g01.pgm rawn0g01.png
+./pnm2png rawn0g02.pgm rawn0g02.png
+./pnm2png rawn0g04.pgm rawn0g04.png
+./pnm2png rawn0g08.pgm rawn0g08.png
+./pnm2png rawn0g16.pgm rawn0g16.png
+# -- full-color
+./pnm2png rawn2c08.ppm rawn2c08.png
+./pnm2png rawn2c16.ppm rawn2c16.png
+# -- palletted
+./pnm2png rawn3p01.ppm rawn3p01.png
+./pnm2png rawn3p02.ppm rawn3p02.png
+./pnm2png rawn3p04.ppm rawn3p04.png
+./pnm2png rawn3p08.ppm rawn3p08.png
+# -- gray with alpha-channel
+./pnm2png -alpha rawn6a08.pgm rawn4a08.pgm rawn4a08.png
+./pnm2png -alpha rawn6a16.pgm rawn4a16.pgm rawn4a16.png
+# -- color with alpha-channel
+./pnm2png -alpha rawn6a08.pgm rawn6a08.ppm rawn6a08.png
+./pnm2png -alpha rawn6a16.pgm rawn6a16.ppm rawn6a16.png
+
diff --git a/libpng/contrib/pngsuite/README b/libpng/contrib/pngsuite/README
new file mode 100644
index 0000000..a7fde8f
--- /dev/null
+++ b/libpng/contrib/pngsuite/README
@@ -0,0 +1,105 @@
+
+pngsuite
+--------
+Copyright (c) Willem van Schaik, 1999, 2011, 2012
+Two images (ftbbn0g01.png and ftbbn0g02.png) are by Glenn Randers-Pehrson, 2012
+
+Permission to use, copy, modify, and distribute these images for any
+purpose and without fee is hereby granted.
+
+The 15 "bas*.png" images are part of the much larger PngSuite test-set of
+images, available for developers of PNG supporting software. The
+complete set, available at http:/www.schaik.com/pngsuite/, contains
+a variety of images to test interlacing, gamma settings, ancillary
+chunks, etc.
+
+The "ft*.png" images are "free/libre" replacements for the transparent
+corresponding t*.png images in the PngSuite.
+
+The images in this directory represent the basic PNG color-types:
+grayscale (1-16 bit deep), full color (8 or 16 bit), paletted
+(1-8 bit) and grayscale or color images with alpha channel. You
+can use them to test the proper functioning of PNG software.
+
+ filename depth type
+ ------------ ------ --------------
+ basn0g01.png 1-bit grayscale
+ basn0g02.png 2-bit grayscale
+ basn0g04.png 4-bit grayscale
+ basn0g08.png 8-bit grayscale
+ basn0g16.png 16-bit grayscale
+ basn2c08.png 8-bit truecolor
+ basn2c16.png 16-bit truecolor
+ basn3p01.png 1-bit paletted
+ basn3p02.png 2-bit paletted
+ basn3p04.png 4-bit paletted
+ basn3p08.png 8-bit paletted
+ basn4a08.png 8-bit gray with alpha
+ basn4a16.png 16-bit gray with alpha
+ basn6a08.png 8-bit RGBA
+ basn6a16.png 16-bit RGBA
+
+ ftbbn0g01.png 1-bit grayscale, black bKGD
+ ftbbn0g02.png 2-bit grayscale, black bKGD
+ ftbbn0g04.png 4-bit grayscale, black bKGD
+ ftbbn2c16.png 16-bit truecolor, black bKGD
+ ftbbn3p08.png 8-bit paletted, black bKGD
+ ftbgn2c16.png 16-bit truecolor, gray bKGD
+ ftbgn3p08.png 8-bit paletted, gray bKGD
+ ftbrn2c08.png 8-bit truecolor, red bKGD
+ ftbwn0g16.png 16-bit gray, white bKGD
+ ftbwn3p08.png 8-bit paletted, white bKGD
+ ftbyn3p08.png 8-bit paletted, yellow bKGD
+ ftp0n0g08.png 8-bit grayscale, opaque
+ ftp0n2c08.png 8-bit truecolor, opaque
+ ftp0n3p08.png 8-bit paletted, opaque
+ ftp1n3p08.png 8-bit paletted, no bKGD
+
+Here is the correct result of typing "pngtest -m bas*.png" in
+this directory:
+
+Testing basn0g01.png: PASS (524 zero samples)
+ Filter 0 was used 32 times
+Testing basn0g02.png: PASS (448 zero samples)
+ Filter 0 was used 32 times
+Testing basn0g04.png: PASS (520 zero samples)
+ Filter 0 was used 32 times
+Testing basn0g08.png: PASS (3 zero samples)
+ Filter 1 was used 9 times
+ Filter 4 was used 23 times
+Testing basn0g16.png: PASS (1 zero samples)
+ Filter 1 was used 1 times
+ Filter 2 was used 31 times
+Testing basn2c08.png: PASS (6 zero samples)
+ Filter 1 was used 5 times
+ Filter 4 was used 27 times
+Testing basn2c16.png: PASS (592 zero samples)
+ Filter 1 was used 1 times
+ Filter 4 was used 31 times
+Testing basn3p01.png: PASS (512 zero samples)
+ Filter 0 was used 32 times
+Testing basn3p02.png: PASS (448 zero samples)
+ Filter 0 was used 32 times
+Testing basn3p04.png: PASS (544 zero samples)
+ Filter 0 was used 32 times
+Testing basn3p08.png: PASS (4 zero samples)
+ Filter 0 was used 32 times
+Testing basn4a08.png: PASS (32 zero samples)
+ Filter 1 was used 1 times
+ Filter 4 was used 31 times
+Testing basn4a16.png: PASS (64 zero samples)
+ Filter 0 was used 1 times
+ Filter 1 was used 2 times
+ Filter 2 was used 1 times
+ Filter 4 was used 28 times
+Testing basn6a08.png: PASS (160 zero samples)
+ Filter 1 was used 1 times
+ Filter 4 was used 31 times
+Testing basn6a16.png: PASS (1072 zero samples)
+ Filter 1 was used 4 times
+ Filter 4 was used 28 times
+libpng passes test
+
+Willem van Schaik
+<willem@schaik.com>
+October 1999
diff --git a/libpng/contrib/pngsuite/basn0g01.png b/libpng/contrib/pngsuite/basn0g01.png
new file mode 100644
index 0000000..e31e1c7
--- /dev/null
+++ b/libpng/contrib/pngsuite/basn0g01.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/basn0g02.png b/libpng/contrib/pngsuite/basn0g02.png
new file mode 100644
index 0000000..68809dd
--- /dev/null
+++ b/libpng/contrib/pngsuite/basn0g02.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/basn0g04.png b/libpng/contrib/pngsuite/basn0g04.png
new file mode 100644
index 0000000..6fa089c
--- /dev/null
+++ b/libpng/contrib/pngsuite/basn0g04.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/basn0g08.png b/libpng/contrib/pngsuite/basn0g08.png
new file mode 100644
index 0000000..bf522ee
--- /dev/null
+++ b/libpng/contrib/pngsuite/basn0g08.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/basn0g16.png b/libpng/contrib/pngsuite/basn0g16.png
new file mode 100644
index 0000000..318ebca
--- /dev/null
+++ b/libpng/contrib/pngsuite/basn0g16.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/basn2c08.png b/libpng/contrib/pngsuite/basn2c08.png
new file mode 100644
index 0000000..21d2f91
--- /dev/null
+++ b/libpng/contrib/pngsuite/basn2c08.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/basn2c16.png b/libpng/contrib/pngsuite/basn2c16.png
new file mode 100644
index 0000000..1bd4a4d
--- /dev/null
+++ b/libpng/contrib/pngsuite/basn2c16.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/basn3p01.png b/libpng/contrib/pngsuite/basn3p01.png
new file mode 100644
index 0000000..a21db59
--- /dev/null
+++ b/libpng/contrib/pngsuite/basn3p01.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/basn3p02.png b/libpng/contrib/pngsuite/basn3p02.png
new file mode 100644
index 0000000..1d0ab61
--- /dev/null
+++ b/libpng/contrib/pngsuite/basn3p02.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/basn3p04.png b/libpng/contrib/pngsuite/basn3p04.png
new file mode 100644
index 0000000..6dc6eac
--- /dev/null
+++ b/libpng/contrib/pngsuite/basn3p04.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/basn3p08.png b/libpng/contrib/pngsuite/basn3p08.png
new file mode 100644
index 0000000..0e07f48
--- /dev/null
+++ b/libpng/contrib/pngsuite/basn3p08.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/basn4a08.png b/libpng/contrib/pngsuite/basn4a08.png
new file mode 100644
index 0000000..3bb0dd0
--- /dev/null
+++ b/libpng/contrib/pngsuite/basn4a08.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/basn4a16.png b/libpng/contrib/pngsuite/basn4a16.png
new file mode 100644
index 0000000..6dbee9f
--- /dev/null
+++ b/libpng/contrib/pngsuite/basn4a16.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/basn6a08.png b/libpng/contrib/pngsuite/basn6a08.png
new file mode 100644
index 0000000..6106230
--- /dev/null
+++ b/libpng/contrib/pngsuite/basn6a08.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/basn6a16.png b/libpng/contrib/pngsuite/basn6a16.png
new file mode 100644
index 0000000..a9bf3cb
--- /dev/null
+++ b/libpng/contrib/pngsuite/basn6a16.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/ftbbn0g01.png b/libpng/contrib/pngsuite/ftbbn0g01.png
new file mode 100644
index 0000000..ba746ff
--- /dev/null
+++ b/libpng/contrib/pngsuite/ftbbn0g01.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/ftbbn0g02.png b/libpng/contrib/pngsuite/ftbbn0g02.png
new file mode 100644
index 0000000..3d83bd6
--- /dev/null
+++ b/libpng/contrib/pngsuite/ftbbn0g02.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/ftbbn0g04.png b/libpng/contrib/pngsuite/ftbbn0g04.png
new file mode 100644
index 0000000..39a7050
--- /dev/null
+++ b/libpng/contrib/pngsuite/ftbbn0g04.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/ftbbn2c16.png b/libpng/contrib/pngsuite/ftbbn2c16.png
new file mode 100644
index 0000000..dd3168e
--- /dev/null
+++ b/libpng/contrib/pngsuite/ftbbn2c16.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/ftbbn3p08.png b/libpng/contrib/pngsuite/ftbbn3p08.png
new file mode 100644
index 0000000..0ede357
--- /dev/null
+++ b/libpng/contrib/pngsuite/ftbbn3p08.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/ftbgn2c16.png b/libpng/contrib/pngsuite/ftbgn2c16.png
new file mode 100644
index 0000000..85cec39
--- /dev/null
+++ b/libpng/contrib/pngsuite/ftbgn2c16.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/ftbgn3p08.png b/libpng/contrib/pngsuite/ftbgn3p08.png
new file mode 100644
index 0000000..8cf2e6f
--- /dev/null
+++ b/libpng/contrib/pngsuite/ftbgn3p08.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/ftbrn2c08.png b/libpng/contrib/pngsuite/ftbrn2c08.png
new file mode 100644
index 0000000..5cca0d6
--- /dev/null
+++ b/libpng/contrib/pngsuite/ftbrn2c08.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/ftbwn0g16.png b/libpng/contrib/pngsuite/ftbwn0g16.png
new file mode 100644
index 0000000..99bdeed
--- /dev/null
+++ b/libpng/contrib/pngsuite/ftbwn0g16.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/ftbwn3p08.png b/libpng/contrib/pngsuite/ftbwn3p08.png
new file mode 100644
index 0000000..eacab7a
--- /dev/null
+++ b/libpng/contrib/pngsuite/ftbwn3p08.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/ftbyn3p08.png b/libpng/contrib/pngsuite/ftbyn3p08.png
new file mode 100644
index 0000000..656db09
--- /dev/null
+++ b/libpng/contrib/pngsuite/ftbyn3p08.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/ftp0n0g08.png b/libpng/contrib/pngsuite/ftp0n0g08.png
new file mode 100644
index 0000000..333465f
--- /dev/null
+++ b/libpng/contrib/pngsuite/ftp0n0g08.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/ftp0n2c08.png b/libpng/contrib/pngsuite/ftp0n2c08.png
new file mode 100644
index 0000000..fc6e42c
--- /dev/null
+++ b/libpng/contrib/pngsuite/ftp0n2c08.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/ftp0n3p08.png b/libpng/contrib/pngsuite/ftp0n3p08.png
new file mode 100644
index 0000000..69a69e5
--- /dev/null
+++ b/libpng/contrib/pngsuite/ftp0n3p08.png
Binary files differ
diff --git a/libpng/contrib/pngsuite/ftp1n3p08.png b/libpng/contrib/pngsuite/ftp1n3p08.png
new file mode 100644
index 0000000..a6c9f35
--- /dev/null
+++ b/libpng/contrib/pngsuite/ftp1n3p08.png
Binary files differ
diff --git a/libpng/contrib/tools/README.txt b/libpng/contrib/tools/README.txt
new file mode 100644
index 0000000..5ddae02
--- /dev/null
+++ b/libpng/contrib/tools/README.txt
@@ -0,0 +1,26 @@
+This directory (contrib/tools) contains tools used by the authors of libpng.
+
+Code and data placed in this directory is not required to build libpng,
+however the code in this directory has been used to generate data or code in
+the body of the libpng source. The source code identifies where this has
+been done. Code in this directory may not compile on all operating systems
+that libpng supports.
+
+NO COPYRIGHT RIGHTS ARE CLAIMED TO ANY OF THE FILES IN THIS DIRECTORY.
+
+To the extent possible under law, the authors have waived all copyright and
+related or neighboring rights to this work. This work is published from:
+United States.
+
+The files may be used freely in any way.
+
+The source code and comments in this directory are the original work of the
+people named below. No other person or organization has made contributions to
+the work in this directory.
+
+ORIGINAL AUTHORS
+ The following people have contributed to the code in this directory. None
+ of the people below claim any rights with regard to the contents of this
+ directory.
+
+ John Bowler <jbowler@acm.org>
diff --git a/libpng/contrib/tools/checksum-icc.c b/libpng/contrib/tools/checksum-icc.c
new file mode 100644
index 0000000..581e708
--- /dev/null
+++ b/libpng/contrib/tools/checksum-icc.c
@@ -0,0 +1,102 @@
+/* checksum-icc.c
+ *
+ * Copyright (c) 2013 John Cunningham Bowler
+ *
+ * Last changed in libpng 1.6.0 [February 14, 2013]
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * Generate crc32 and adler32 checksums of the given input files, used to
+ * generate check-codes for use when matching ICC profiles within libpng.
+ */
+#include <stdio.h>
+
+#include <zlib.h>
+
+static int
+read_one_file(FILE *ip, const char *name)
+{
+ uLong length = 0;
+ uLong a32 = adler32(0, NULL, 0);
+ uLong c32 = crc32(0, NULL, 0);
+ Byte header[132];
+
+ for (;;)
+ {
+ int ch = getc(ip);
+ Byte b;
+
+ if (ch == EOF) break;
+
+ b = (Byte)ch;
+
+ if (length < sizeof header)
+ header[length] = b;
+
+ ++length;
+ a32 = adler32(a32, &b, 1);
+ c32 = crc32(c32, &b, 1);
+ }
+
+ if (ferror(ip))
+ return 0;
+
+ /* Success */
+ printf("PNG_ICC_CHECKSUM(0x%8.8lx, 0x%8.8lx,\n PNG_MD5("
+ "0x%2.2x%2.2x%2.2x%2.2x, 0x%2.2x%2.2x%2.2x%2.2x, 0x%2.2x%2.2x%2.2x%2.2x,"
+ " 0x%2.2x%2.2x%2.2x%2.2x), %d,\n"
+ " \"%4.4d/%2.2d/%2.2d %2.2d:%2.2d:%2.2d\", %lu, \"%s\")\n",
+ (unsigned long)a32, (unsigned long)c32,
+ header[84], header[85], header[86], header[87],
+ header[88], header[89], header[90], header[91],
+ header[92], header[93], header[94], header[95],
+ header[96], header[97], header[98], header[99],
+# define u16(x) (header[x] * 256 + header[x+1])
+# define u32(x) (u16(x) * 65536 + u16(x+2))
+ u32(64), u16(24), u16(26), u16(28), u16(30), u16(32), u16(34),
+ (unsigned long)length, name);
+
+ return 1;
+}
+
+int main(int argc, char **argv)
+{
+ int err = 0;
+
+ printf("/* adler32, crc32, MD5[16], intent, date, length, file-name */\n");
+
+ if (argc > 1)
+ {
+ int i;
+
+ for (i=1; i<argc; ++i)
+ {
+ FILE *ip = fopen(argv[i], "rb");
+
+ if (ip == NULL || !read_one_file(ip, argv[i]))
+ {
+ err = 1;
+ perror(argv[i]);
+ fprintf(stderr, "%s: read error\n", argv[i]);
+ printf("/* ERROR: %s */\n", argv[i]);
+ }
+
+ (void)fclose(ip);
+ }
+ }
+
+ else
+ {
+ if (!read_one_file(stdin, "-"))
+ {
+ err = 1;
+ perror("stdin");
+ fprintf(stderr, "stdin: read error\n");
+ printf("/* ERROR: stdin */\n");
+ }
+ }
+
+ return err;
+}
diff --git a/libpng/contrib/tools/chkfmt b/libpng/contrib/tools/chkfmt
new file mode 100755
index 0000000..9da6475
--- /dev/null
+++ b/libpng/contrib/tools/chkfmt
@@ -0,0 +1,137 @@
+#!/bin/sh
+#
+# Check the format of the source files in the current directory - checks for a
+# line length of 80 characters max and no tab characters.
+#
+# Optionally arguments are files or directories to check.
+#
+# -v: output the long lines (makes fixing them easier)
+# -e: spawn an editor for each file that needs a change ($EDITOR must be
+# defined). When using -e the script MUST be run from an interactive
+# command line.
+verbose=
+edit=
+vers=
+test "$1" = "-v" && {
+ shift
+ verbose=yes
+}
+test "$1" = "-e" && {
+ shift
+ if test -n "$EDITOR"
+ then
+ edit=yes
+
+ # Copy the standard streams for the editor
+ exec 3>&0 4>&1 5>&2
+ else
+ echo "chkfmt -e: EDITOR must be defined" >&2
+ exit 1
+ fi
+}
+
+# Function to edit a single file - if the file isn't changed ask the user
+# whether or not to continue. This stuff only works if the script is run from
+# the command line (otherwise, don't specify -e or you will be sorry).
+doed(){
+ cp "$file" "$file".orig
+ "$EDITOR" "$file" 0>&3 1>&4 2>&5 3>&- 4>&- 5>&- || exit 1
+ if cmp -s "$file".orig "$file"
+ then
+ rm "$file".orig
+ echo -n "$file: file not changed, type anything to continue: " >&5
+ read ans 0>&3
+ test -n "$ans" || return 1
+ fi
+ return 0
+}
+
+# In beta versions the version string which appears in files can be a little
+# long and cause spuriously overlong lines. To avoid this subtitute the version
+# string with a 'standard' version a.b.cc before checking for long lines.
+if test -r png.h
+then
+ vers="`sed -n -e \
+ 's/^#define PNG_LIBPNG_VER_STRING .\([0-9]\.[0-9]\.[0-9][0-9a-z]*\).$/\1/p' \
+ png.h`"
+ echo "chkfmt: checking version $vers"
+fi
+if test -z "$vers"
+then
+ echo "chkfmt: png.h not found, ignoring version number" >&2
+fi
+
+test -n "$1" || set -- .
+find "$@" \( -type d \( -name '.git' -o -name '.libs' -o -name 'projects' \) \
+ -prune \) -o \( -type f \
+ ! -name '*.[oa]' ! -name '*.l[oa]' ! -name '*.png' ! -name '*.out' \
+ ! -name '*.jpg' ! -name '*.patch' ! -name '*.obj' ! -name '*.exe' \
+ ! -name '*.com' ! -name '*.tar.*' ! -name '*.zip' ! -name '*.ico' \
+ ! -name '*.res' ! -name '*.rc' ! -name '*.mms' ! -name '*.rej' \
+ ! -name '*.dsp' ! -name '*.orig' ! -name '*.dfn' ! -name '*.swp' \
+ ! -name '~*' ! -name '*.3' \
+ ! -name 'missing' ! -name 'mkinstalldirs' ! -name 'depcomp' \
+ ! -name 'aclocal.m4' ! -name 'install-sh' ! -name 'Makefile.in' \
+ ! -name 'ltmain.sh' ! -name 'config*' -print \) | {
+ st=0
+ while read file
+ do
+ case "$file" in
+ *.mak|*[Mm]akefile.*|*[Mm]akefile)
+ # Makefiles require tabs, dependency lines can be this long.
+ check_tabs=
+ line_length=100;;
+ *.awk)
+ # Includes literal tabs
+ check_tabs=
+ # The following is arbitrary
+ line_length=132;;
+ *contrib/*/*.[ch])
+ check_tabs=yes
+ line_length=96;;
+ *)
+ check_tabs=yes
+ line_length=80;;
+ esac
+
+ # Note that vers can only contain 0-9, . and a-z
+ if test -n "$vers"
+ then
+ sed -e "s/$vers/a.b.cc/g" "$file" >"$file".$$
+ else
+ cp "$file" "$file".$$
+ fi
+ splt="`fold -$line_length "$file".$$ | diff -c "$file".$$ -`"
+ rm "$file".$$
+
+ if test -n "$splt"
+ then
+ echo "$file: lines too long"
+ st=1
+ if test -n "$EDITOR" -a -n "$edit"
+ then
+ doed "$file" || exit 1
+ elif test -n "$verbose"
+ then
+ echo "$splt"
+ fi
+ fi
+ if test -n "$check_tabs"
+ then
+ tab="`tr -c -d '\t' <"$file"`"
+ if test -n "$tab"
+ then
+ echo "$file: file contains tab characters"
+ st=1
+ if test -n "$EDITOR" -a -n "$edit"
+ then
+ doed "$file" || exit 1
+ elif test -n "$verbose"
+ then
+ echo "$splt"
+ fi
+ fi
+ fi
+ done
+ exit $st
+}
diff --git a/libpng/contrib/tools/cvtcolor.c b/libpng/contrib/tools/cvtcolor.c
new file mode 100644
index 0000000..e6793c7
--- /dev/null
+++ b/libpng/contrib/tools/cvtcolor.c
@@ -0,0 +1,188 @@
+/*-
+ * convert.c
+ *
+ * Last changed in libpng 1.6.0 [February 14, 2013]
+ *
+ * COPYRIGHT: Written by John Cunningham Bowler, 2013.
+ * To the extent possible under law, the author has waived all copyright and
+ * related or neighboring rights to this work. This work is published from:
+ * United States.
+ *
+ * Convert 8-bit sRGB or 16-bit linear values to another format.
+ */
+#define _ISOC99_SOURCE 1
+
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include <stdio.h>
+
+#include <fenv.h>
+
+#include "sRGB.h"
+
+static void
+usage(const char *prog)
+{
+ fprintf(stderr,
+ "%s: usage: %s [-linear|-sRGB] [-gray|-color] component{1,4}\n",
+ prog, prog);
+ exit(1);
+}
+
+unsigned long
+component(const char *prog, const char *arg, int issRGB)
+{
+ char *ep;
+ unsigned long c = strtoul(arg, &ep, 0);
+
+ if (ep <= arg || *ep || c > 65535 || (issRGB && c > 255))
+ {
+ fprintf(stderr, "%s: %s: invalid component value (%lu)\n", prog, arg, c);
+ usage(prog);
+ }
+
+ return c;
+}
+
+int
+main(int argc, const char **argv)
+{
+ const char *prog = *argv++;
+ int to_linear = 0, to_gray = 0, to_color = 0;
+ int channels = 0;
+ double c[4];
+
+ /* FE_TONEAREST is the IEEE754 round to nearest, preferring even, mode; i.e.
+ * everything rounds to the nearest value except that '.5' rounds to the
+ * nearest even value.
+ */
+ fesetround(FE_TONEAREST);
+
+ c[3] = c[2] = c[1] = c[0] = 0;
+
+ while (--argc > 0 && **argv == '-')
+ {
+ const char *arg = 1+*argv++;
+
+ if (strcmp(arg, "sRGB") == 0)
+ to_linear = 0;
+
+ else if (strcmp(arg, "linear") == 0)
+ to_linear = 1;
+
+ else if (strcmp(arg, "gray") == 0)
+ to_gray = 1, to_color = 0;
+
+ else if (strcmp(arg, "color") == 0)
+ to_gray = 0, to_color = 1;
+
+ else
+ usage(prog);
+ }
+
+ switch (argc)
+ {
+ default:
+ usage(prog);
+ break;
+
+ case 4:
+ c[3] = component(prog, argv[3], to_linear);
+ ++channels;
+ case 3:
+ c[2] = component(prog, argv[2], to_linear);
+ ++channels;
+ case 2:
+ c[1] = component(prog, argv[1], to_linear);
+ ++channels;
+ case 1:
+ c[0] = component(prog, argv[0], to_linear);
+ ++channels;
+ break;
+ }
+
+ if (to_linear)
+ {
+ int i;
+ int components = channels;
+
+ if ((components & 1) == 0)
+ --components;
+
+ for (i=0; i<components; ++i) c[i] = linear_from_sRGB(c[i] / 255);
+ if (components < channels)
+ c[components] = c[components] / 255;
+ }
+
+ else
+ {
+ int i;
+ for (i=0; i<4; ++i) c[i] /= 65535;
+
+ if ((channels & 1) == 0)
+ {
+ double alpha = c[channels-1];
+
+ if (alpha > 0)
+ for (i=0; i<channels-1; ++i) c[i] /= alpha;
+ else
+ for (i=0; i<channels-1; ++i) c[i] = 1;
+ }
+ }
+
+ if (to_gray)
+ {
+ if (channels < 3)
+ {
+ fprintf(stderr, "%s: too few channels (%d) for -gray\n",
+ prog, channels);
+ usage(prog);
+ }
+
+ c[0] = YfromRGB(c[0], c[1], c[2]);
+ channels -= 2;
+ }
+
+ if (to_color)
+ {
+ if (channels > 2)
+ {
+ fprintf(stderr, "%s: too many channels (%d) for -color\n",
+ prog, channels);
+ usage(prog);
+ }
+
+ c[3] = c[1]; /* alpha, if present */
+ c[2] = c[1] = c[0];
+ }
+
+ if (to_linear)
+ {
+ int i;
+ if ((channels & 1) == 0)
+ {
+ double alpha = c[channels-1];
+ for (i=0; i<channels-1; ++i) c[i] *= alpha;
+ }
+
+ for (i=0; i<channels; ++i) c[i] = nearbyint(c[i] * 65535);
+ }
+
+ else /* to sRGB */
+ {
+ int i = (channels+1)&~1;
+ while (--i >= 0)
+ c[i] = sRGB_from_linear(c[i]);
+
+ for (i=0; i<channels; ++i) c[i] = nearbyint(c[i] * 255);
+ }
+
+ {
+ int i;
+ for (i=0; i<channels; ++i) printf(" %g", c[i]);
+ }
+ printf("\n");
+
+ return 0;
+}
diff --git a/libpng/contrib/tools/genpng.c b/libpng/contrib/tools/genpng.c
new file mode 100644
index 0000000..ce43260
--- /dev/null
+++ b/libpng/contrib/tools/genpng.c
@@ -0,0 +1,867 @@
+/*- genpng
+ *
+ * COPYRIGHT: Written by John Cunningham Bowler, 2015.
+ * To the extent possible under law, the author has waived all copyright and
+ * related or neighboring rights to this work. This work is published from:
+ * United States.
+ *
+ * Generate a PNG with an alpha channel, correctly.
+ *
+ * This is a test case generator; the resultant PNG files are only of interest
+ * to those of us who care about whether the edges of circles are green, red,
+ * or yellow.
+ *
+ * The program generates an RGB+Alpha PNG of a given size containing the given
+ * shapes on a transparent background:
+ *
+ * genpng width height { shape }
+ * shape ::= color width shape x1 y1 x2 y2
+ *
+ * 'color' is:
+ *
+ * black white red green yellow blue brown purple pink orange gray cyan
+ *
+ * The point is to have colors that are linguistically meaningful plus that old
+ * bugbear of the department store dress murders, Cyan, the only color we argue
+ * about.
+ *
+ * 'shape' is:
+ *
+ * circle: an ellipse
+ * square: a rectangle
+ * line: a straight line
+ *
+ * Each shape is followed by four numbers, these are two points in the output
+ * coordinate space (as real numbers) which describe the circle, square, or
+ * line. The shape is filled if it is preceded by 'filled' (not valid for
+ * 'line') or is drawn with a line, in which case the width of the line must
+ * precede the shape.
+ *
+ * The whole set of information can be repeated as many times as desired:
+ *
+ * shape ::= color width shape x1 y1 x2 y2
+ *
+ * color ::= black|white|red|green|yellow|blue
+ * color ::= brown|purple|pink|orange|gray|cyan
+ * width ::= filled
+ * width ::= <number>
+ * shape ::= circle|square|line
+ * x1 ::= <number>
+ * x2 ::= <number>
+ * y1 ::= <number>
+ * y2 ::= <number>
+ *
+ * The output PNG is generated by down-sampling a 4x supersampled image using
+ * a bi-cubic filter. The bi-cubic has a 2 (output) pixel width, so an 8x8
+ * array of super-sampled points contribute to each output pixel. The value of
+ * a super-sampled point is found using an unfiltered, aliased, infinite
+ * precision image: Each shape from the last to the first is checked to see if
+ * the point is in the drawn area and, if it is, the color of the point is the
+ * color of the shape and the alpha is 1, if not the previous shape is checked.
+ *
+ * This is an aliased algorithm because no filtering is done; a point is either
+ * inside or outside each shape and 'close' points do not contribute to the
+ * sample. The down-sampling is relied on to correct the error of not using
+ * a filter.
+ *
+ * The line end-caps are 'flat'; they go through the points. The square line
+ * joins are mitres; the outside of the lines are continued to the point of
+ * intersection.
+ */
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <math.h>
+
+/* Normally use <png.h> here to get the installed libpng, but this is done to
+ * ensure the code picks up the local libpng implementation:
+ */
+#include "../../png.h"
+
+#if defined(PNG_SIMPLIFIED_WRITE_SUPPORTED) && defined(PNG_STDIO_SUPPORTED)
+
+static const struct color
+{
+ const char *name;
+ double red;
+ double green;
+ double blue;
+} colors[] =
+/* color ::= black|white|red|green|yellow|blue
+ * color ::= brown|purple|pink|orange|gray|cyan
+ */
+{
+ { "black", 0, 0, 0 },
+ { "white", 1, 1, 1 },
+ { "red", 1, 0, 0 },
+ { "green", 0, 1, 0 },
+ { "yellow", 1, 1, 0 },
+ { "blue", 0, 0, 1 },
+ { "brown", .5, .125, 0 },
+ { "purple", 1, 0, 1 },
+ { "pink", 1, .5, .5 },
+ { "orange", 1, .5, 0 },
+ { "gray", 0, .5, .5 },
+ { "cyan", 0, 1, 1 }
+};
+#define color_count ((sizeof colors)/(sizeof colors[0]))
+
+static const struct color *
+color_of(const char *arg)
+{
+ int icolor = color_count;
+
+ while (--icolor >= 0)
+ {
+ if (strcmp(colors[icolor].name, arg) == 0)
+ return colors+icolor;
+ }
+
+ fprintf(stderr, "genpng: invalid color %s\n", arg);
+ exit(1);
+}
+
+static double
+width_of(const char *arg)
+{
+ if (strcmp(arg, "filled") == 0)
+ return 0;
+
+ else
+ {
+ char *ep = NULL;
+ double w = strtod(arg, &ep);
+
+ if (ep != NULL && *ep == 0 && w > 0)
+ return w;
+ }
+
+ fprintf(stderr, "genpng: invalid line width %s\n", arg);
+ exit(1);
+}
+
+static double
+coordinate_of(const char *arg)
+{
+ char *ep = NULL;
+ double w = strtod(arg, &ep);
+
+ if (ep != NULL && *ep == 0)
+ return w;
+
+ fprintf(stderr, "genpng: invalid coordinate value %s\n", arg);
+ exit(1);
+}
+
+struct arg; /* forward declaration */
+
+typedef int (*shape_fn_ptr)(const struct arg *arg, double x, double y);
+ /* A function to determine if (x,y) is inside the shape.
+ *
+ * There are two implementations:
+ *
+ * inside_fn: returns true if the point is inside
+ * check_fn: returns;
+ * -1: the point is outside the shape by more than the filter width (2)
+ * 0: the point may be inside the shape
+ * +1: the point is inside the shape by more than the filter width
+ */
+#define OUTSIDE (-1)
+#define INSIDE (1)
+
+struct arg
+{
+ const struct color *color;
+ shape_fn_ptr inside_fn;
+ shape_fn_ptr check_fn;
+ double width; /* line width, 0 for 'filled' */
+ double x1, y1, x2, y2;
+};
+
+/* IMPLEMENTATION NOTE:
+ *
+ * We want the contribution of each shape to the sample corresponding to each
+ * pixel. This could be obtained by super sampling the image to infinite
+ * dimensions, finding each point within the shape and assigning that a value
+ * '1' while leaving every point outside the shape with value '0' then
+ * downsampling to the image size with sinc; computationally very expensive.
+ *
+ * Approximations are as follows:
+ *
+ * 1) If the pixel coordinate is within the shape assume the sample has the
+ * shape color and is opaque, else assume there is no contribution from
+ * the shape.
+ *
+ * This is the equivalent of aliased rendering or resampling an image with
+ * a block filter. The maximum error in the calculated alpha (which will
+ * always be 0 or 1) is 0.5.
+ *
+ * 2) If the shape is within a square of size 1x1 centered on the pixel assume
+ * that the shape obscures an amount of the pixel equal to its area within
+ * that square.
+ *
+ * This is the equivalent of 'pixel coverage' alpha calculation or resampling
+ * an image with a bi-linear filter. The maximum error is over 0.2, but the
+ * results are often acceptable.
+ *
+ * This can be approximated by applying (1) to a super-sampled image then
+ * downsampling with a bi-linear filter. The error in the super-sampled
+ * image is 0.5 per sample, but the resampling reduces this.
+ *
+ * 3) Use a better filter with a super-sampled image; in the limit this is the
+ * sinc() approach.
+ *
+ * 4) Do the geometric calculation; a bivariate definite integral across the
+ * shape, unfortunately this means evaluating Si(x), the integral of sinc(x),
+ * which is still a lot of math.
+ *
+ * This code uses approach (3) with a bi-cubic filter and 8x super-sampling
+ * and method (1) for the super-samples. This means that the sample is either
+ * 0 or 1, depending on whether the sub-pixel is within or outside the shape.
+ * The bi-cubic weights are also fixed and the 16 required weights are
+ * pre-computed here (note that the 'scale' setting will need to be changed if
+ * 'super' is increased).
+ *
+ * The code also calculates a sum to the edge of the filter. This is not
+ * currently used by could be used to optimize the calculation.
+ */
+#if 0 /* bc code */
+scale=10
+super=8
+define bicubic(x) {
+ if (x <= 1) return (1.5*x - 2.5)*x*x + 1;
+ if (x < 2) return (((2.5 - 0.5*x)*x - 4)*x + 2);
+ return 0;
+}
+define sum(x) {
+ auto s;
+ s = 0;
+ while (x < 2*super) {
+ s = s + bicubic(x/super);
+ x = x + 1;
+ }
+ return s;
+}
+define results(x) {
+ auto b, s;
+ b = bicubic(x/super);
+ s = sum(x);
+
+ print " /*", x, "*/ { ", b, ", ", s, " }";
+ return 1;
+}
+x=0
+while (x<2*super) {
+ x = x + results(x)
+ if (x < 2*super) print ","
+ print "\n"
+}
+quit
+#endif
+
+#define BICUBIC1(x) /* |x| <= 1 */ ((1.5*(x)* - 2.5)*(x)*(x) + 1)
+#define BICUBIC2(x) /* 1 < |x| < 2 */ (((2.5 - 0.5*(x))*(x) - 4)*(x) + 2)
+#define FILTER_WEIGHT 9 /* Twice the first sum below */
+#define FILTER_WIDTH 2 /* Actually half the width; -2..+2 */
+#define FILTER_STEPS 8 /* steps per filter unit */
+static const double
+bicubic[16][2] =
+{
+ /* These numbers are exact; the weight for the filter is 1/9, but this
+ * would make the numbers inexact, so it is not included here.
+ */
+ /* bicubic sum */
+ /* 0*/ { 1.0000000000, 4.5000000000 },
+ /* 1*/ { .9638671875, 3.5000000000 },
+ /* 2*/ { .8671875000, 2.5361328125 },
+ /* 3*/ { .7275390625, 1.6689453125 },
+ /* 4*/ { .5625000000, .9414062500 },
+ /* 5*/ { .3896484375, .3789062500 },
+ /* 6*/ { .2265625000, -.0107421875 },
+ /* 7*/ { .0908203125, -.2373046875 },
+ /* 8*/ { 0, -.3281250000 },
+ /* 9*/ { -.0478515625, -.3281250000 },
+ /*10*/ { -.0703125000, -.2802734375 },
+ /*11*/ { -.0732421875, -.2099609375 },
+ /*12*/ { -.0625000000, -.1367187500 },
+ /*13*/ { -.0439453125, -.0742187500 },
+ /*14*/ { -.0234375000, -.0302734375 },
+ /*15*/ { -.0068359375, -.0068359375 }
+};
+
+static double
+alpha_calc(const struct arg *arg, double x, double y)
+{
+ /* For [x-2..x+2],[y-2,y+2] calculate the weighted bicubic given a function
+ * which tells us whether a point is inside or outside the shape. First
+ * check if we need to do this at all:
+ */
+ switch (arg->check_fn(arg, x, y))
+ {
+ case OUTSIDE:
+ return 0; /* all samples outside the shape */
+
+ case INSIDE:
+ return 1; /* all samples inside the shape */
+
+ default:
+ {
+ int dy;
+ double alpha = 0;
+
+# define FILTER_D (FILTER_WIDTH*FILTER_STEPS-1)
+ for (dy=-FILTER_D; dy<=FILTER_D; ++dy)
+ {
+ double wy = bicubic[abs(dy)][0];
+
+ if (wy != 0)
+ {
+ double alphay = 0;
+ int dx;
+
+ for (dx=-FILTER_D; dx<=FILTER_D; ++dx)
+ {
+ double wx = bicubic[abs(dx)][0];
+
+ if (wx != 0 && arg->inside_fn(arg, x+dx/16, y+dy/16))
+ alphay += wx;
+ }
+
+ alpha += wy * alphay;
+ }
+ }
+
+ /* This needs to be weighted for each dimension: */
+ return alpha / (FILTER_WEIGHT*FILTER_WEIGHT);
+ }
+ }
+}
+
+/* These are the shape functions. */
+/* "square",
+ * { inside_square_filled, check_square_filled },
+ * { inside_square, check_square }
+ */
+static int
+square_check(double x, double y, double x1, double y1, double x2, double y2)
+ /* Is x,y inside the square (x1,y1)..(x2,y2)? */
+{
+ /* Do a modified Cohen-Sutherland on one point, bit patterns that indicate
+ * 'outside' are:
+ *
+ * x<x1 | x<y1 | x<x2 | x<y2
+ * 0 x 0 x To the right
+ * 1 x 1 x To the left
+ * x 0 x 0 Below
+ * x 1 x 1 Above
+ *
+ * So 'inside' is (x<x1) != (x<x2) && (y<y1) != (y<y2);
+ */
+ return ((x<x1) ^ (x<x2)) & ((y<y1) ^ (y<y2));
+}
+
+static int
+inside_square_filled(const struct arg *arg, double x, double y)
+{
+ return square_check(x, y, arg->x1, arg->y1, arg->x2, arg->y2);
+}
+
+static int
+square_check_line(const struct arg *arg, double x, double y, double w)
+ /* Check for a point being inside the boundaries implied by the given arg
+ * and assuming a width 2*w each side of the boundaries. This returns the
+ * 'check' INSIDE/OUTSIDE/0 result but note the semantics:
+ *
+ * +--------------+
+ * | | OUTSIDE
+ * | INSIDE |
+ * | |
+ * +--------------+
+ *
+ * And '0' means within the line boundaries.
+ */
+{
+ double cx = (arg->x1+arg->x2)/2;
+ double wx = fabs(arg->x1-arg->x2)/2;
+ double cy = (arg->y1+arg->y2)/2;
+ double wy = fabs(arg->y1-arg->y2)/2;
+
+ if (square_check(x, y, cx-wx-w, cy-wy-w, cx+wx+w, cy+wy+w))
+ {
+ /* Inside, but maybe too far; check for the redundant case where
+ * the lines overlap:
+ */
+ wx -= w;
+ wy -= w;
+ if (wx > 0 && wy > 0 && square_check(x, y, cx-wx, cy-wy, cx+wx, cy+wy))
+ return INSIDE; /* between (inside) the boundary lines. */
+
+ return 0; /* inside the lines themselves. */
+ }
+
+ return OUTSIDE; /* outside the boundary lines. */
+}
+
+static int
+check_square_filled(const struct arg *arg, double x, double y)
+{
+ /* The filter extends +/-FILTER_WIDTH each side of each output point, so
+ * the check has to expand and contract the square by that amount; '0'
+ * means close enough to the edge of the square that the bicubic filter has
+ * to be run, OUTSIDE means alpha==0, INSIDE means alpha==1.
+ */
+ return square_check_line(arg, x, y, FILTER_WIDTH);
+}
+
+static int
+inside_square(const struct arg *arg, double x, double y)
+{
+ /* Return true if within the drawn lines, else false, no need to distinguish
+ * INSIDE vs OUTSIDE here:
+ */
+ return square_check_line(arg, x, y, arg->width/2) == 0;
+}
+
+static int
+check_square(const struct arg *arg, double x, double y)
+{
+ /* So for this function a result of 'INSIDE' means inside the actual lines.
+ */
+ double w = arg->width/2;
+
+ if (square_check_line(arg, x, y, w+FILTER_WIDTH) == 0)
+ {
+ /* Somewhere close to the boundary lines. If far enough inside one of
+ * them then we can return INSIDE:
+ */
+ w -= FILTER_WIDTH;
+
+ if (w > 0 && square_check_line(arg, x, y, w) == 0)
+ return INSIDE;
+
+ /* Point is somewhere in the filter region: */
+ return 0;
+ }
+
+ else /* Inside or outside the square by more than w+FILTER_WIDTH. */
+ return OUTSIDE;
+}
+
+/* "circle",
+ * { inside_circle_filled, check_circle_filled },
+ * { inside_circle, check_circle }
+ *
+ * The functions here are analoguous to the square ones; however, they check
+ * the corresponding ellipse as opposed to the rectangle.
+ */
+static int
+circle_check(double x, double y, double x1, double y1, double x2, double y2)
+{
+ if (square_check(x, y, x1, y1, x2, y2))
+ {
+ /* Inside the square, so maybe inside the circle too: */
+ const double cx = (x1 + x2)/2;
+ const double cy = (y1 + y2)/2;
+ const double dx = x1 - x2;
+ const double dy = y1 - y2;
+
+ x = (x - cx)/dx;
+ y = (y - cy)/dy;
+
+ /* It is outside if the distance from the center is more than half the
+ * diameter:
+ */
+ return x*x+y*y < .25;
+ }
+
+ return 0; /* outside */
+}
+
+static int
+inside_circle_filled(const struct arg *arg, double x, double y)
+{
+ return circle_check(x, y, arg->x1, arg->y1, arg->x2, arg->y2);
+}
+
+static int
+circle_check_line(const struct arg *arg, double x, double y, double w)
+ /* Check for a point being inside the boundaries implied by the given arg
+ * and assuming a width 2*w each side of the boundaries. This function has
+ * the same semantic as square_check_line but tests the circle.
+ */
+{
+ double cx = (arg->x1+arg->x2)/2;
+ double wx = fabs(arg->x1-arg->x2)/2;
+ double cy = (arg->y1+arg->y2)/2;
+ double wy = fabs(arg->y1-arg->y2)/2;
+
+ if (circle_check(x, y, cx-wx-w, cy-wy-w, cx+wx+w, cy+wy+w))
+ {
+ /* Inside, but maybe too far; check for the redundant case where
+ * the lines overlap:
+ */
+ wx -= w;
+ wy -= w;
+ if (wx > 0 && wy > 0 && circle_check(x, y, cx-wx, cy-wy, cx+wx, cy+wy))
+ return INSIDE; /* between (inside) the boundary lines. */
+
+ return 0; /* inside the lines themselves. */
+ }
+
+ return OUTSIDE; /* outside the boundary lines. */
+}
+
+static int
+check_circle_filled(const struct arg *arg, double x, double y)
+{
+ return circle_check_line(arg, x, y, FILTER_WIDTH);
+}
+
+static int
+inside_circle(const struct arg *arg, double x, double y)
+{
+ return circle_check_line(arg, x, y, arg->width/2) == 0;
+}
+
+static int
+check_circle(const struct arg *arg, double x, double y)
+{
+ /* Exactly as the 'square' code. */
+ double w = arg->width/2;
+
+ if (circle_check_line(arg, x, y, w+FILTER_WIDTH) == 0)
+ {
+ w -= FILTER_WIDTH;
+
+ if (w > 0 && circle_check_line(arg, x, y, w) == 0)
+ return INSIDE;
+
+ /* Point is somewhere in the filter region: */
+ return 0;
+ }
+
+ else /* Inside or outside the square by more than w+FILTER_WIDTH. */
+ return OUTSIDE;
+}
+
+/* "line",
+ * { NULL, NULL }, There is no 'filled' line.
+ * { inside_line, check_line }
+ */
+static int
+line_check(double x, double y, double x1, double y1, double x2, double y2,
+ double w, double expand)
+{
+ /* Shift all the points to (arg->x1, arg->y1) */
+ double lx = x2 - x1;
+ double ly = y2 - y1;
+ double len2 = lx*lx + ly*ly;
+ double cross, dot;
+
+ x -= x1;
+ y -= y1;
+
+ /* The dot product is the distance down the line, the cross product is
+ * the distance away from the line:
+ *
+ * distance = |cross| / sqrt(len2)
+ */
+ cross = x * ly - y * lx;
+
+ /* If 'distance' is more than w the point is definitely outside the line:
+ *
+ * distance >= w
+ * |cross| >= w * sqrt(len2)
+ * cross^2 >= w^2 * len2:
+ */
+ if (cross*cross >= (w+expand)*(w+expand)*len2)
+ return 0; /* outside */
+
+ /* Now find the distance *along* the line; this comes from the dot product
+ * lx.x+ly.y. The actual distance (in pixels) is:
+ *
+ * distance = dot / sqrt(len2)
+ */
+ dot = lx * x + ly * y;
+
+ /* The test for 'outside' is:
+ *
+ * distance < 0 || distance > sqrt(len2)
+ * -> dot / sqrt(len2) > sqrt(len2)
+ * -> dot > len2
+ *
+ * But 'expand' is used for the filter width and needs to be handled too:
+ */
+ return dot > -expand && dot < len2+expand;
+}
+
+static int
+inside_line(const struct arg *arg, double x, double y)
+{
+ return line_check(x, y, arg->x1, arg->y1, arg->x2, arg->y2, arg->width/2, 0);
+}
+
+static int
+check_line(const struct arg *arg, double x, double y)
+{
+ /* The end caps of the line must be checked too; it's not enough just to
+ * widen the line by FILTER_WIDTH; 'expand' exists for this purpose:
+ */
+ if (line_check(x, y, arg->x1, arg->y1, arg->x2, arg->y2, arg->width/2,
+ FILTER_WIDTH))
+ {
+ /* Inside the line+filter; far enough inside that the filter isn't
+ * required?
+ */
+ if (arg->width > 2*FILTER_WIDTH &&
+ line_check(x, y, arg->x1, arg->y1, arg->x2, arg->y2, arg->width/2,
+ -FILTER_WIDTH))
+ return INSIDE;
+
+ return 0;
+ }
+
+ return OUTSIDE;
+}
+
+static const struct
+{
+ const char *name;
+ shape_fn_ptr function[2/*fill,line*/][2];
+# define FN_INSIDE 0
+# define FN_CHECK 1
+} shape_defs[] =
+{
+ { "square",
+ { { inside_square_filled, check_square_filled },
+ { inside_square, check_square } }
+ },
+ { "circle",
+ { { inside_circle_filled, check_circle_filled },
+ { inside_circle, check_circle } }
+ },
+ { "line",
+ { { NULL, NULL },
+ { inside_line, check_line } }
+ }
+};
+
+#define shape_count ((sizeof shape_defs)/(sizeof shape_defs[0]))
+
+static shape_fn_ptr
+shape_of(const char *arg, double width, int f)
+{
+ unsigned int i;
+
+ for (i=0; i<shape_count; ++i) if (strcmp(shape_defs[i].name, arg) == 0)
+ {
+ shape_fn_ptr fn = shape_defs[i].function[width != 0][f];
+
+ if (fn != NULL)
+ return fn;
+
+ fprintf(stderr, "genpng: %s %s not supported\n",
+ width == 0 ? "filled" : "unfilled", arg);
+ exit(1);
+ }
+
+ fprintf(stderr, "genpng: %s: not a valid shape name\n", arg);
+ exit(1);
+}
+
+static void
+parse_arg(struct arg *arg, const char **argv/*7 arguments*/)
+{
+ /* shape ::= color width shape x1 y1 x2 y2 */
+ arg->color = color_of(argv[0]);
+ arg->width = width_of(argv[1]);
+ arg->inside_fn = shape_of(argv[2], arg->width, FN_INSIDE);
+ arg->check_fn = shape_of(argv[2], arg->width, FN_CHECK);
+ arg->x1 = coordinate_of(argv[3]);
+ arg->y1 = coordinate_of(argv[4]);
+ arg->x2 = coordinate_of(argv[5]);
+ arg->y2 = coordinate_of(argv[6]);
+}
+
+static png_uint_32
+read_wh(const char *name, const char *str)
+ /* read a PNG width or height */
+{
+ char *ep = NULL;
+ unsigned long ul = strtoul(str, &ep, 10);
+
+ if (ep != NULL && *ep == 0 && ul > 0 && ul <= 0x7fffffff)
+ return (png_uint_32)/*SAFE*/ul;
+
+ fprintf(stderr, "genpng: %s: invalid number %s\n", name, str);
+ exit(1);
+}
+
+static void
+pixel(png_uint_16p p, struct arg *args, int nargs, double x, double y)
+{
+ /* Fill in the pixel by checking each shape (args[nargs]) for effects on
+ * the corresponding sample:
+ */
+ double r=0, g=0, b=0, a=0;
+
+ while (--nargs >= 0 && a != 1)
+ {
+ /* NOTE: alpha_calc can return a value outside the range 0..1 with the
+ * bicubic filter.
+ */
+ const double alpha = alpha_calc(args+nargs, x, y) * (1-a);
+
+ r += alpha * args[nargs].color->red;
+ g += alpha * args[nargs].color->green;
+ b += alpha * args[nargs].color->blue;
+ a += alpha;
+ }
+
+ /* 'a' may be negative or greater than 1; if it is, negative clamp the
+ * pixel to 0 if >1 clamp r/g/b:
+ */
+ if (a > 0)
+ {
+ if (a > 1)
+ {
+ if (r > 1) r = 1;
+ if (g > 1) g = 1;
+ if (b > 1) b = 1;
+ a = 1;
+ }
+
+ /* And fill in the pixel: */
+ p[0] = (png_uint_16)/*SAFE*/round(r * 65535);
+ p[1] = (png_uint_16)/*SAFE*/round(g * 65535);
+ p[2] = (png_uint_16)/*SAFE*/round(b * 65535);
+ p[3] = (png_uint_16)/*SAFE*/round(a * 65535);
+ }
+
+ else
+ p[3] = p[2] = p[1] = p[0] = 0;
+}
+
+int
+main(int argc, const char **argv)
+{
+ int convert_to_8bit = 0;
+
+ /* There is one option: --8bit: */
+ if (argc > 1 && strcmp(argv[1], "--8bit") == 0)
+ --argc, ++argv, convert_to_8bit = 1;
+
+ if (argc >= 3)
+ {
+ png_uint_16p buffer;
+ int nshapes;
+ png_image image;
+# define max_shapes 256
+ struct arg arg_list[max_shapes];
+
+ /* The libpng Simplified API write code requires a fully initialized
+ * structure.
+ */
+ memset(&image, 0, sizeof image);
+ image.version = PNG_IMAGE_VERSION;
+ image.opaque = NULL;
+ image.width = read_wh("width", argv[1]);
+ image.height = read_wh("height", argv[2]);
+ image.format = PNG_FORMAT_LINEAR_RGB_ALPHA;
+ image.flags = 0;
+ image.colormap_entries = 0;
+
+ /* Check the remainder of the arguments */
+ for (nshapes=0; 3+7*(nshapes+1) <= argc && nshapes < max_shapes;
+ ++nshapes)
+ parse_arg(arg_list+nshapes, argv+3+7*nshapes);
+
+ if (3+7*nshapes != argc)
+ {
+ fprintf(stderr, "genpng: %s: too many arguments\n", argv[3+7*nshapes]);
+ return 1;
+ }
+
+ /* Create the buffer: */
+ buffer = malloc(PNG_IMAGE_SIZE(image));
+
+ if (buffer != NULL)
+ {
+ png_uint_32 y;
+
+ /* Write each row... */
+ for (y=0; y<image.height; ++y)
+ {
+ png_uint_32 x;
+
+ /* Each pixel in each row: */
+ for (x=0; x<image.width; ++x)
+ pixel(buffer + 4*(x + y*image.width), arg_list, nshapes, x, y);
+ }
+
+ /* Write the result (to stdout) */
+ if (png_image_write_to_stdio(&image, stdout, convert_to_8bit,
+ buffer, 0/*row_stride*/, NULL/*colormap*/))
+ {
+ free(buffer);
+ return 0; /* success */
+ }
+
+ else
+ fprintf(stderr, "genpng: write stdout: %s\n", image.message);
+
+ free(buffer);
+ }
+
+ else
+ fprintf(stderr, "genpng: out of memory: %lu bytes\n",
+ (unsigned long)PNG_IMAGE_SIZE(image));
+ }
+
+ else
+ {
+ /* Wrong number of arguments */
+ fprintf(stderr, "genpng: usage: genpng [--8bit] width height {shape}\n"
+ " Generate a transparent PNG in RGBA (truecolor+alpha) format\n"
+ " containing the given shape or shapes. Shapes are defined:\n"
+ "\n"
+ " shape ::= color width shape x1 y1 x2 y2\n"
+ " color ::= black|white|red|green|yellow|blue\n"
+ " color ::= brown|purple|pink|orange|gray|cyan\n"
+ " width ::= filled|<number>\n"
+ " shape ::= circle|square|line\n"
+ " x1,x2 ::= <number>\n"
+ " y1,y2 ::= <number>\n"
+ "\n"
+ " Numbers are floating point numbers describing points relative to\n"
+ " the top left of the output PNG as pixel coordinates. The 'width'\n"
+ " parameter is either the width of the line (in output pixels) used\n"
+ " to draw the shape or 'filled' to indicate that the shape should\n"
+ " be filled with the color.\n"
+ "\n"
+ " Colors are interpreted loosely to give access to the eight full\n"
+ " intensity RGB values:\n"
+ "\n"
+ " black, red, green, blue, yellow, cyan, purple, white,\n"
+ "\n"
+ " Cyan is full intensity blue+green; RGB(0,1,1), plus the following\n"
+ " lower intensity values:\n"
+ "\n"
+ " brown: red+orange: RGB(0.5, 0.125, 0) (dark red+orange)\n"
+ " pink: red+white: RGB(1.0, 0.5, 0.5)\n"
+ " orange: red+yellow: RGB(1.0, 0.5, 0)\n"
+ " gray: black+white: RGB(0.5, 0.5, 0.5)\n"
+ "\n"
+ " The RGB values are selected to make detection of aliasing errors\n"
+ " easy. The names are selected to make the description of errors\n"
+ " easy.\n"
+ "\n"
+ " The PNG is written to stdout, if --8bit is given a 32bpp RGBA sRGB\n"
+ " file is produced, otherwise a 64bpp RGBA linear encoded file is\n"
+ " written.\n");
+ }
+
+ return 1;
+}
+#endif /* SIMPLIFIED_WRITE && STDIO */
diff --git a/libpng/contrib/tools/intgamma.sh b/libpng/contrib/tools/intgamma.sh
new file mode 100755
index 0000000..41c5d6d
--- /dev/null
+++ b/libpng/contrib/tools/intgamma.sh
@@ -0,0 +1,110 @@
+#!/bin/sh
+#
+# intgamma.sh
+#
+# Last changed in libpng 1.6.0 [February 14, 2013]
+#
+# COPYRIGHT: Written by John Cunningham Bowler, 2013.
+# To the extent possible under law, the author has waived all copyright and
+# related or neighboring rights to this work. This work is published from:
+# United States.
+#
+# Shell script to generate png.c 8-bit and 16-bit log tables (see the code in
+# png.c for details).
+#
+# This script uses the "bc" arbitrary precision calculator to calculate 32-bit
+# fixed point values of logarithms appropriate to finding the log of an 8-bit
+# (0..255) value and a similar table for the exponent calculation.
+#
+# "bc" must be on the path when the script is executed, and the math library
+# (-lm) must be available
+#
+# function to print out a list of numbers as integers; the function truncates
+# the integers which must be one-per-line
+function print(){
+ awk 'BEGIN{
+ str = ""
+ }
+ {
+ sub("\\.[0-9]*$", "")
+ if ($0 == "")
+ $0 = "0"
+
+ if (str == "")
+ t = " " $0 "U"
+ else
+ t = str ", " $0 "U"
+
+ if (length(t) >= 80) {
+ print str ","
+ str = " " $0 "U"
+ } else
+ str = t
+ }
+ END{
+ print str
+ }'
+}
+#
+# The logarithm table.
+cat <<END
+/* 8-bit log table: png_8bit_l2[128]
+ * This is a table of -log(value/255)/log(2) for 'value' in the range 128 to
+ * 255, so it's the base 2 logarithm of a normalized 8-bit floating point
+ * mantissa. The numbers are 32-bit fractions.
+ */
+static const png_uint_32
+png_8bit_l2[128] =
+{
+END
+#
+bc -lqws <<END | print
+f=65536*65536/l(2)
+for (i=128;i<256;++i) { .5 - l(i/255)*f; }
+END
+echo '};'
+echo
+#
+# The exponent table.
+cat <<END
+/* The 'exp()' case must invert the above, taking a 20-bit fixed point
+ * logarithmic value and returning a 16 or 8-bit number as appropriate. In
+ * each case only the low 16 bits are relevant - the fraction - since the
+ * integer bits (the top 4) simply determine a shift.
+ *
+ * The worst case is the 16-bit distinction between 65535 and 65534; this
+ * requires perhaps spurious accuracy in the decoding of the logarithm to
+ * distinguish log2(65535/65534.5) - 10^-5 or 17 bits. There is little chance
+ * of getting this accuracy in practice.
+ *
+ * To deal with this the following exp() function works out the exponent of the
+ * frational part of the logarithm by using an accurate 32-bit value from the
+ * top four fractional bits then multiplying in the remaining bits.
+ */
+static const png_uint_32
+png_32bit_exp[16] =
+{
+END
+#
+bc -lqws <<END | print
+f=l(2)/16
+for (i=0;i<16;++i) {
+ x = .5 + e(-i*f)*2^32;
+ if (x >= 2^32) x = 2^32-1;
+ x;
+}
+END
+echo '};'
+echo
+#
+# And the table of adjustment values.
+cat <<END
+/* Adjustment table; provided to explain the numbers in the code below. */
+#if 0
+END
+bc -lqws <<END | awk '{ printf "%5d %s\n", 12-NR, $0 }'
+for (i=11;i>=0;--i){
+ (1 - e(-(2^i)/65536*l(2))) * 2^(32-i)
+}
+END
+echo '#endif'
diff --git a/libpng/contrib/tools/makesRGB.c b/libpng/contrib/tools/makesRGB.c
new file mode 100644
index 0000000..e66c9f1
--- /dev/null
+++ b/libpng/contrib/tools/makesRGB.c
@@ -0,0 +1,430 @@
+/* makesRGB.c -- build sRGB-to-linear and linear-to-sRGB conversion tables
+ *
+ * Last changed in libpng 1.6.0 [February 14, 2013]
+ *
+ * COPYRIGHT: Written by John Cunningham Bowler, 2013.
+ * To the extent possible under law, the author has waived all copyright and
+ * related or neighboring rights to this work. This work is published from:
+ * United States.
+ *
+ * Make a table to convert 8-bit sRGB encoding values into the closest 16-bit
+ * linear value.
+ *
+ * Make two tables to take a linear value scaled to 255*65535 and return an
+ * approximation to the 8-bit sRGB encoded value. Calculate the error in these
+ * tables and display it.
+ */
+#define _C99_SOURCE 1
+#include <stdio.h>
+#include <math.h>
+#include <stdlib.h>
+
+/* pngpriv.h includes the definition of 'PNG_sRGB_FROM_LINEAR' which is required
+ * to verify the actual code.
+ */
+#include "../../pngpriv.h"
+
+#include "sRGB.h"
+
+/* The tables are declared 'const' in pngpriv.h, so this redefines the tables to
+ * be used.
+ */
+#define png_sRGB_table sRGB_table
+#define png_sRGB_base sRGB_base
+#define png_sRGB_delta sRGB_delta
+
+static png_uint_16 png_sRGB_table[256];
+static png_uint_16 png_sRGB_base[512];
+static png_byte png_sRGB_delta[512];
+
+static const unsigned int max_input = 255*65535;
+
+double
+fsRGB(double l)
+{
+ return sRGB_from_linear(l/max_input);
+}
+
+double
+sRGB(unsigned int i)
+{
+ return fsRGB(i);
+}
+
+double
+finvsRGB(unsigned int i)
+{
+ return 65535 * linear_from_sRGB(i/255.);
+}
+
+png_uint_16
+invsRGB(unsigned int i)
+{
+ unsigned int x = nearbyint(finvsRGB(i));
+
+ if (x > 65535)
+ {
+ fprintf(stderr, "invsRGB(%u) overflows to %u\n", i, x);
+ exit(1);
+ }
+
+ return (png_uint_16)x;
+}
+
+int
+main(int argc, char **argv)
+{
+ unsigned int i, i16, ibase;
+ double min_error = 0;
+ double max_error = 0;
+ double min_error16 = 0;
+ double max_error16 = 0;
+ double adjust;
+ double adjust_lo = 0.4, adjust_hi = 0.6, adjust_mid = 0.5;
+ unsigned int ec_lo = 0, ec_hi = 0, ec_mid = 0;
+ unsigned int error_count = 0;
+ unsigned int error_count16 = 0;
+ int test_only = 0;
+
+ if (argc > 1)
+ test_only = strcmp("--test", argv[1]) == 0;
+
+ /* Initialize the encoding table first. */
+ for (i=0; i<256; ++i)
+ {
+ png_sRGB_table[i] = invsRGB(i);
+ }
+
+ /* Now work out the decoding tables (this is where the error comes in because
+ * there are 512 set points and 512 straight lines between them.)
+ */
+ for (;;)
+ {
+ if (ec_lo == 0)
+ adjust = adjust_lo;
+
+ else if (ec_hi == 0)
+ adjust = adjust_hi;
+
+ else if (ec_mid == 0)
+ adjust = adjust_mid;
+
+ else if (ec_mid < ec_hi)
+ adjust = (adjust_mid + adjust_hi)/2;
+
+ else if (ec_mid < ec_lo)
+ adjust = (adjust_mid + adjust_lo)/2;
+
+ else
+ {
+ fprintf(stderr, "not reached: %u .. %u .. %u\n", ec_lo, ec_mid, ec_hi);
+ exit(1);
+ }
+
+ /* Calculate the table using the current 'adjust' */
+ for (i=0; i<=511; ++i)
+ {
+ double lo = 255 * sRGB(i << 15);
+ double hi = 255 * sRGB((i+1) << 15);
+ unsigned int calc;
+
+ calc = nearbyint((lo+adjust) * 256);
+ if (calc > 65535)
+ {
+ fprintf(stderr, "table[%d][0]: overflow %08x (%d)\n", i, calc,
+ calc);
+ exit(1);
+ }
+ png_sRGB_base[i] = calc;
+
+ calc = nearbyint((hi-lo) * 32);
+ if (calc > 255)
+ {
+ fprintf(stderr, "table[%d][1]: overflow %08x (%d)\n", i, calc,
+ calc);
+ exit(1);
+ }
+ png_sRGB_delta[i] = calc;
+ }
+
+ /* Check the 16-bit linear values alone: */
+ error_count16 = 0;
+ for (i16=0; i16 <= 65535; ++i16)
+ {
+ unsigned int i = 255*i16;
+ unsigned int iexact = nearbyint(255*sRGB(i));
+ unsigned int icalc = PNG_sRGB_FROM_LINEAR(i);
+
+ if (icalc != iexact)
+ ++error_count16;
+ }
+
+ /* Now try changing the adjustment. */
+ if (ec_lo == 0)
+ ec_lo = error_count16;
+
+ else if (ec_hi == 0)
+ ec_hi = error_count16;
+
+ else if (ec_mid == 0)
+ {
+ ec_mid = error_count16;
+ printf("/* initial error counts: %u .. %u .. %u */\n", ec_lo, ec_mid,
+ ec_hi);
+ }
+
+ else if (error_count16 < ec_mid)
+ {
+ printf("/* adjust (mid ): %f: %u -> %u */\n", adjust, ec_mid,
+ error_count16);
+ ec_mid = error_count16;
+ adjust_mid = adjust;
+ }
+
+ else if (adjust < adjust_mid && error_count16 < ec_lo)
+ {
+ printf("/* adjust (low ): %f: %u -> %u */\n", adjust, ec_lo,
+ error_count16);
+ ec_lo = error_count16;
+ adjust_lo = adjust;
+ }
+
+ else if (adjust > adjust_mid && error_count16 < ec_hi)
+ {
+ printf("/* adjust (high): %f: %u -> %u */\n", adjust, ec_hi,
+ error_count16);
+ ec_hi = error_count16;
+ adjust_hi = adjust;
+ }
+
+ else
+ {
+ adjust = adjust_mid;
+ printf("/* adjust: %f: %u */\n", adjust, ec_mid);
+ break;
+ }
+ }
+
+ /* For each entry in the table try to adjust it to minimize the error count
+ * in that entry. Each entry corresponds to 128 input values.
+ */
+ for (ibase=0; ibase<65536; ibase+=128)
+ {
+ png_uint_16 base = png_sRGB_base[ibase >> 7], trybase = base, ob=base;
+ png_byte delta = png_sRGB_delta[ibase >> 7], trydelta = delta, od=delta;
+ unsigned int ecbase = 0, eco;
+
+ for (;;)
+ {
+ png_sRGB_base[ibase >> 7] = trybase;
+ png_sRGB_delta[ibase >> 7] = trydelta;
+
+ /* Check the 16-bit linear values alone: */
+ error_count16 = 0;
+ for (i16=ibase; i16 < ibase+128; ++i16)
+ {
+ unsigned int i = 255*i16;
+ unsigned int iexact = nearbyint(255*sRGB(i));
+ unsigned int icalc = PNG_sRGB_FROM_LINEAR(i);
+
+ if (icalc != iexact)
+ ++error_count16;
+ }
+
+ if (error_count16 == 0)
+ break;
+
+ if (ecbase == 0)
+ {
+ eco = ecbase = error_count16;
+ ++trybase; /* First test */
+ }
+
+ else if (error_count16 < ecbase)
+ {
+ if (trybase > base)
+ {
+ base = trybase;
+ ++trybase;
+ }
+ else if (trybase < base)
+ {
+ base = trybase;
+ --trybase;
+ }
+ else if (trydelta > delta)
+ {
+ delta = trydelta;
+ ++trydelta;
+ }
+ else if (trydelta < delta)
+ {
+ delta = trydelta;
+ --trydelta;
+ }
+ else
+ {
+ fprintf(stderr, "makesRGB: impossible\n");
+ exit(1);
+ }
+ ecbase = error_count16;
+ }
+
+ else
+ {
+ if (trybase > base)
+ trybase = base-1;
+ else if (trybase < base)
+ {
+ trybase = base;
+ ++trydelta;
+ }
+ else if (trydelta > delta)
+ trydelta = delta-1;
+ else if (trydelta < delta)
+ break; /* end of tests */
+ }
+ }
+
+ png_sRGB_base[ibase >> 7] = base;
+ png_sRGB_delta[ibase >> 7] = delta;
+ if (base != ob || delta != od)
+ {
+ printf("/* table[%u]={%u,%u} -> {%u,%u} %u -> %u errors */\n",
+ ibase>>7, ob, od, base, delta, eco, ecbase);
+ }
+ else if (0)
+ printf("/* table[%u]={%u,%u} %u errors */\n", ibase>>7, ob, od,
+ ecbase);
+ }
+
+ /* Only do the full (slow) test at the end: */
+ min_error = -.4999;
+ max_error = .4999;
+ error_count = 0;
+
+ for (i=0; i <= max_input; ++i)
+ {
+ unsigned int iexact = nearbyint(255*sRGB(i));
+ unsigned int icalc = PNG_sRGB_FROM_LINEAR(i);
+
+ if (icalc != iexact)
+ {
+ double err = 255*sRGB(i) - icalc;
+
+ if (err > (max_error+.001) || err < (min_error-.001))
+ {
+ printf(
+ "/* 0x%08x: exact: %3d, got: %3d [tables: %08x, %08x] (%f) */\n",
+ i, iexact, icalc, png_sRGB_base[i>>15],
+ png_sRGB_delta[i>>15], err);
+ }
+
+ ++error_count;
+ if (err > max_error)
+ max_error = err;
+ else if (err < min_error)
+ min_error = err;
+ }
+ }
+
+ /* Re-check the 16-bit cases too, including the warning if there is an error
+ * bigger than 1.
+ */
+ error_count16 = 0;
+ max_error16 = 0;
+ min_error16 = 0;
+ for (i16=0; i16 <= 65535; ++i16)
+ {
+ unsigned int i = 255*i16;
+ unsigned int iexact = nearbyint(255*sRGB(i));
+ unsigned int icalc = PNG_sRGB_FROM_LINEAR(i);
+
+ if (icalc != iexact)
+ {
+ double err = 255*sRGB(i) - icalc;
+
+ ++error_count16;
+ if (err > max_error16)
+ max_error16 = err;
+ else if (err < min_error16)
+ min_error16 = err;
+
+ if (abs(icalc - iexact) > 1)
+ printf(
+ "/* 0x%04x: exact: %3d, got: %3d [tables: %08x, %08x] (%f) */\n",
+ i16, iexact, icalc, png_sRGB_base[i>>15],
+ png_sRGB_delta[i>>15], err);
+ }
+ }
+
+ /* Check the round trip for each 8-bit sRGB value. */
+ for (i16=0; i16 <= 255; ++i16)
+ {
+ unsigned int i = 255 * png_sRGB_table[i16];
+ unsigned int iexact = nearbyint(255*sRGB(i));
+ unsigned int icalc = PNG_sRGB_FROM_LINEAR(i);
+
+ if (i16 != iexact)
+ {
+ fprintf(stderr, "8-bit rounding error: %d -> %d\n", i16, iexact);
+ exit(1);
+ }
+
+ if (icalc != i16)
+ {
+ double finv = finvsRGB(i16);
+
+ printf("/* 8-bit roundtrip error: %d -> %f -> %d(%f) */\n",
+ i16, finv, icalc, fsRGB(255*finv));
+ }
+ }
+
+
+ printf("/* error: %g - %g, %u (%g%%) of readings inexact */\n",
+ min_error, max_error, error_count, (100.*error_count)/max_input);
+ printf("/* 16-bit error: %g - %g, %u (%g%%) of readings inexact */\n",
+ min_error16, max_error16, error_count16, (100.*error_count16)/65535);
+
+ if (!test_only)
+ {
+ printf("PNG_CONST png_uint_16 png_sRGB_table[256] =\n{\n ");
+ for (i=0; i<255; )
+ {
+ do
+ {
+ printf("%d,", png_sRGB_table[i++]);
+ }
+ while ((i & 0x7) != 0 && i<255);
+ if (i<255) printf("\n ");
+ }
+ printf("%d\n};\n\n", png_sRGB_table[i]);
+
+
+ printf("PNG_CONST png_uint_16 png_sRGB_base[512] =\n{\n ");
+ for (i=0; i<511; )
+ {
+ do
+ {
+ printf("%d,", png_sRGB_base[i++]);
+ }
+ while ((i & 0x7) != 0 && i<511);
+ if (i<511) printf("\n ");
+ }
+ printf("%d\n};\n\n", png_sRGB_base[i]);
+
+ printf("PNG_CONST png_byte png_sRGB_delta[512] =\n{\n ");
+ for (i=0; i<511; )
+ {
+ do
+ {
+ printf("%d,", png_sRGB_delta[i++]);
+ }
+ while ((i & 0xf) != 0 && i<511);
+ if (i<511) printf("\n ");
+ }
+ printf("%d\n};\n\n", png_sRGB_delta[i]);
+ }
+
+ return 0;
+}
diff --git a/libpng/contrib/tools/png-fix-itxt.c b/libpng/contrib/tools/png-fix-itxt.c
new file mode 100644
index 0000000..c7654c1
--- /dev/null
+++ b/libpng/contrib/tools/png-fix-itxt.c
@@ -0,0 +1,164 @@
+
+/* png-fix-itxt version 1.0.0
+ *
+ * Copyright 2015 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.18 [July 23, 2015]
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * Usage:
+ *
+ * png-fix-itxt.exe < bad.png > good.png
+ *
+ * Fixes a PNG file written with libpng-1.6.0 or 1.6.1 that has one or more
+ * uncompressed iTXt chunks. Assumes that the actual length is greater
+ * than or equal to the value in the length byte, and that the CRC is
+ * correct for the actual length. This program hunts for the CRC and
+ * adjusts the length byte accordingly. It is not an error to process a
+ * PNG file that has no iTXt chunks or one that has valid iTXt chunks;
+ * such files will simply be copied.
+ *
+ * Requires zlib (for crc32 and Z_NULL); build with
+ *
+ * gcc -O -o png-fix-itxt png-fix-itxt.c -lz
+ *
+ * If you need to handle iTXt chunks larger than 500000 kbytes you must
+ * rebuild png-fix-itxt with a larger values of MAX_LENGTH (or a smaller value
+ * if you know you will never encounter such huge iTXt chunks).
+ */
+
+#include <stdio.h>
+#include <zlib.h>
+
+#define MAX_LENGTH 500000
+
+/* Read one character (inchar), also return octet (c), break if EOF */
+#define GETBREAK inchar=getchar(); \
+ c=(inchar & 0xffU);\
+ if (inchar != c) break
+int
+main(void)
+{
+ unsigned int i;
+ unsigned char buf[MAX_LENGTH];
+ unsigned long crc;
+ unsigned char c;
+ int inchar;
+
+/* Skip 8-byte signature */
+ for (i=8; i; i--)
+ {
+ GETBREAK;
+ putchar(c);
+ }
+
+if (inchar == c) /* !EOF */
+for (;;)
+ {
+ /* Read the length */
+ unsigned long length; /* must be 32 bits! */
+ GETBREAK; buf[0] = c; length = c; length <<= 8;
+ GETBREAK; buf[1] = c; length += c; length <<= 8;
+ GETBREAK; buf[2] = c; length += c; length <<= 8;
+ GETBREAK; buf[3] = c; length += c;
+
+ /* Read the chunkname */
+ GETBREAK; buf[4] = c;
+ GETBREAK; buf[5] = c;
+ GETBREAK; buf[6] = c;
+ GETBREAK; buf[7] = c;
+
+
+ /* The iTXt chunk type expressed as integers is (105, 84, 88, 116) */
+ if (buf[4] == 105 && buf[5] == 84 && buf[6] == 88 && buf[7] == 116)
+ {
+ if (length >= MAX_LENGTH-12)
+ break; /* To do: handle this more gracefully */
+
+ /* Initialize the CRC */
+ crc = crc32(0, Z_NULL, 0);
+
+ /* Copy the data bytes */
+ for (i=8; i < length + 12; i++)
+ {
+ GETBREAK; buf[i] = c;
+ }
+
+ if (inchar != c) /* EOF */
+ break;
+
+ /* Calculate the CRC */
+ crc = crc32(crc, buf+4, (uInt)length+4);
+
+ for (;;)
+ {
+ /* Check the CRC */
+ if (((crc >> 24) & 0xffU) == buf[length+8] &&
+ ((crc >> 16) & 0xffU) == buf[length+9] &&
+ ((crc >> 8) & 0xffU) == buf[length+10] &&
+ ((crc ) & 0xffU) == buf[length+11])
+ break;
+
+ length++;
+
+ if (length >= MAX_LENGTH-12)
+ break;
+
+ GETBREAK;
+ buf[length+11] = c;
+
+ /* Update the CRC */
+ crc = crc32(crc, buf+7+length, 1);
+ }
+
+ if (inchar != c) /* EOF */
+ break;
+
+ /* Update length bytes */
+ buf[0] = (unsigned char)((length >> 24) & 0xffU);
+ buf[1] = (unsigned char)((length >> 16) & 0xffU);
+ buf[2] = (unsigned char)((length >> 8) & 0xffU);
+ buf[3] = (unsigned char)((length ) & 0xffU);
+
+ /* Write the fixed iTXt chunk (length, name, data, crc) */
+ for (i=0; i<length+12; i++)
+ putchar(buf[i]);
+ }
+
+ else
+ {
+ if (inchar != c) /* EOF */
+ break;
+
+ /* Copy bytes that were already read (length and chunk name) */
+ for (i=0; i<8; i++)
+ putchar(buf[i]);
+
+ /* Copy data bytes and CRC */
+ for (i=8; i< length+12; i++)
+ {
+ GETBREAK;
+ putchar(c);
+ }
+
+ if (inchar != c) /* EOF */
+ {
+ break;
+ }
+
+ /* The IEND chunk type expressed as integers is (73, 69, 78, 68) */
+ if (buf[4] == 73 && buf[5] == 69 && buf[6] == 78 && buf[7] == 68)
+ break;
+ }
+
+ if (inchar != c) /* EOF */
+ break;
+
+ if (buf[4] == 73 && buf[5] == 69 && buf[6] == 78 && buf[7] == 68)
+ break;
+ }
+
+ return 0;
+}
diff --git a/libpng/contrib/tools/pngfix.c b/libpng/contrib/tools/pngfix.c
new file mode 100644
index 0000000..7fde31c
--- /dev/null
+++ b/libpng/contrib/tools/pngfix.c
@@ -0,0 +1,4049 @@
+/* pngfix.c
+ *
+ * Copyright (c) 2014-2015 John Cunningham Bowler
+ *
+ * Last changed in libpng 1.6.20 [December 3, 2015]
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * Tool to check and fix the zlib inflate 'too far back' problem.
+ * See the usage message for more information.
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+#include <limits.h>
+#include <errno.h>
+#include <assert.h>
+
+#define implies(x,y) assert(!(x) || (y))
+
+#ifdef __GNUC__
+ /* This is used to fix the error:
+ *
+ * pngfix.c:
+ * In function 'zlib_advance':
+ * pngfix.c:181:13: error: assuming signed overflow does not
+ * occur when simplifying conditional to constant [-Werror=strict-overflow]
+ */
+# define FIX_GCC volatile
+#else
+# define FIX_GCC
+#endif
+
+#define PROGRAM_NAME "pngfix"
+
+/* Define the following to use this program against your installed libpng,
+ * rather than the one being built here:
+ */
+#ifdef PNG_FREESTANDING_TESTS
+# include <png.h>
+#else
+# include "../../png.h"
+#endif
+
+#if PNG_LIBPNG_VER < 10603 /* 1.6.3 */
+# error "pngfix will not work with libpng prior to 1.6.3"
+#endif
+
+#ifdef PNG_SETJMP_SUPPORTED
+#include <setjmp.h>
+
+#if defined(PNG_READ_SUPPORTED) && defined(PNG_EASY_ACCESS_SUPPORTED) &&\
+ (defined(PNG_READ_DEINTERLACE_SUPPORTED) ||\
+ defined(PNG_READ_INTERLACING_SUPPORTED))
+
+/* zlib.h defines the structure z_stream, an instance of which is included
+ * in this structure and is required for decompressing the LZ compressed
+ * data in PNG files.
+ */
+#ifndef ZLIB_CONST
+ /* We must ensure that zlib uses 'const' in declarations. */
+# define ZLIB_CONST
+#endif
+#include <zlib.h>
+#ifdef const
+ /* zlib.h sometimes #defines const to nothing, undo this. */
+# undef const
+#endif
+
+/* zlib.h has mediocre z_const use before 1.2.6, this stuff is for compatibility
+ * with older builds.
+ */
+#if ZLIB_VERNUM < 0x1260
+# define PNGZ_MSG_CAST(s) constcast(char*,s)
+# define PNGZ_INPUT_CAST(b) constcast(png_bytep,b)
+#else
+# define PNGZ_MSG_CAST(s) (s)
+# define PNGZ_INPUT_CAST(b) (b)
+#endif
+
+#ifndef PNG_MAXIMUM_INFLATE_WINDOW
+# error "pngfix not supported in this libpng version"
+#endif
+
+#if ZLIB_VERNUM >= 0x1240
+
+/* Copied from pngpriv.h */
+#ifdef __cplusplus
+# define voidcast(type, value) static_cast<type>(value)
+# define constcast(type, value) const_cast<type>(value)
+# define aligncast(type, value) \
+ static_cast<type>(static_cast<void*>(value))
+# define aligncastconst(type, value) \
+ static_cast<type>(static_cast<const void*>(value))
+#else
+# define voidcast(type, value) (value)
+# define constcast(type, value) ((type)(value))
+# define aligncast(type, value) ((void*)(value))
+# define aligncastconst(type, value) ((const void*)(value))
+#endif /* __cplusplus */
+
+#if PNG_LIBPNG_VER < 10700
+/* Chunk tags (copied from pngpriv.h) */
+#define PNG_32b(b,s) ((png_uint_32)(b) << (s))
+#define PNG_U32(b1,b2,b3,b4) \
+ (PNG_32b(b1,24) | PNG_32b(b2,16) | PNG_32b(b3,8) | PNG_32b(b4,0))
+
+/* Constants for known chunk types. */
+#define png_IDAT PNG_U32( 73, 68, 65, 84)
+#define png_IEND PNG_U32( 73, 69, 78, 68)
+#define png_IHDR PNG_U32( 73, 72, 68, 82)
+#define png_PLTE PNG_U32( 80, 76, 84, 69)
+#define png_bKGD PNG_U32( 98, 75, 71, 68)
+#define png_cHRM PNG_U32( 99, 72, 82, 77)
+#define png_fRAc PNG_U32(102, 82, 65, 99) /* registered, not defined */
+#define png_gAMA PNG_U32(103, 65, 77, 65)
+#define png_gIFg PNG_U32(103, 73, 70, 103)
+#define png_gIFt PNG_U32(103, 73, 70, 116) /* deprecated */
+#define png_gIFx PNG_U32(103, 73, 70, 120)
+#define png_hIST PNG_U32(104, 73, 83, 84)
+#define png_iCCP PNG_U32(105, 67, 67, 80)
+#define png_iTXt PNG_U32(105, 84, 88, 116)
+#define png_oFFs PNG_U32(111, 70, 70, 115)
+#define png_pCAL PNG_U32(112, 67, 65, 76)
+#define png_pHYs PNG_U32(112, 72, 89, 115)
+#define png_sBIT PNG_U32(115, 66, 73, 84)
+#define png_sCAL PNG_U32(115, 67, 65, 76)
+#define png_sPLT PNG_U32(115, 80, 76, 84)
+#define png_sRGB PNG_U32(115, 82, 71, 66)
+#define png_sTER PNG_U32(115, 84, 69, 82)
+#define png_tEXt PNG_U32(116, 69, 88, 116)
+#define png_tIME PNG_U32(116, 73, 77, 69)
+#define png_tRNS PNG_U32(116, 82, 78, 83)
+#define png_zTXt PNG_U32(122, 84, 88, 116)
+#endif
+
+/* The 8-byte signature as a pair of 32-bit quantities */
+#define sig1 PNG_U32(137, 80, 78, 71)
+#define sig2 PNG_U32( 13, 10, 26, 10)
+
+/* Is the chunk critical? */
+#define CRITICAL(chunk) (((chunk) & PNG_U32(32,0,0,0)) == 0)
+
+/* Is it safe to copy? */
+#define SAFE_TO_COPY(chunk) (((chunk) & PNG_U32(0,0,0,32)) != 0)
+
+/* Fix ups for builds with limited read support */
+#ifndef PNG_ERROR_TEXT_SUPPORTED
+# define png_error(a,b) png_err(a)
+#endif
+
+/********************************* UTILITIES **********************************/
+/* UNREACHED is a value to cause an assert to fail. Because of the way the
+ * assert macro is written the string "UNREACHED" is produced in the error
+ * message.
+ */
+#define UNREACHED 0
+
+/* 80-bit number handling - a PNG image can be up to (2^31-1)x(2^31-1) 8-byte
+ * (16-bit RGBA) pixels in size; that's less than 2^65 bytes or 2^68 bits, so
+ * arithmetic of 80-bit numbers is sufficient. This representation uses an
+ * arbitrary length array of png_uint_16 digits (0..65535). The representation
+ * is little endian.
+ *
+ * The arithmetic functions take zero to two uarb values together with the
+ * number of digits in those values and write the result to the given uarb
+ * (always the first argument) returning the number of digits in the result.
+ * If the result is negative the return value is also negative (this would
+ * normally be an error).
+ */
+typedef png_uint_16 udigit; /* A 'unum' is an array of these */
+typedef png_uint_16p uarb;
+typedef png_const_uint_16p uarbc;
+
+#define UDIGITS(unum) ((sizeof unum)/(sizeof (udigit))
+ /* IMPORTANT: only apply this to an array, applied to a pointer the result
+ * will typically be '2', which is not useful.
+ */
+
+static int
+uarb_set(uarb result, png_alloc_size_t val)
+ /* Set (initialize) 'result' to 'val'. The size required for 'result' must
+ * be determined by the caller from a knowledge of the maximum for 'val'.
+ */
+{
+ int ndigits = 0;
+
+ while (val > 0)
+ {
+ result[ndigits++] = (png_uint_16)(val & 0xffff);
+ val >>= 16;
+ }
+
+ return ndigits;
+}
+
+static int
+uarb_copy(uarb to, uarb from, int idigits)
+ /* Copy a uarb, may reduce the digit count */
+{
+ int d, odigits;
+
+ for (d=odigits=0; d<idigits; ++d)
+ if ((to[d] = from[d]) != 0)
+ odigits = d+1;
+
+ return odigits;
+}
+
+static int
+uarb_inc(uarb num, int in_digits, png_int_32 add)
+ /* This is a signed 32-bit add, except that to avoid overflow the value added
+ * or subtracted must be no more than 2^31-65536. A negative result
+ * indicates a negative number (which is an error below). The size of
+ * 'num' should be max(in_digits+1,2) for arbitrary 'add' but can be just
+ * in_digits+1 if add is known to be in the range -65535..65535.
+ */
+{
+ FIX_GCC int out_digits = 0;
+
+ while (out_digits < in_digits)
+ {
+ add += num[out_digits];
+ num[out_digits++] = (png_uint_16)(add & 0xffff);
+ add >>= 16;
+ }
+
+ while (add != 0 && add != (-1))
+ {
+ num[out_digits++] = (png_uint_16)(add & 0xffff);
+ add >>= 16;
+ }
+
+ if (add == 0)
+ {
+ while (out_digits > 0 && num[out_digits-1] == 0)
+ --out_digits;
+ return out_digits; /* may be 0 */
+ }
+
+ else /* negative result */
+ {
+ while (out_digits > 1 && num[out_digits-1] == 0xffff)
+ --out_digits;
+
+ return -out_digits;
+ }
+}
+
+static int
+uarb_add32(uarb num, int in_digits, png_uint_32 add)
+ /* As above but this works with any 32-bit value and only does 'add' */
+{
+ if (in_digits > 0)
+ {
+ in_digits = uarb_inc(num, in_digits, add & 0xffff);
+ return uarb_inc(num+1, in_digits-1, add >> 16)+1;
+ }
+
+ return uarb_set(num, add);
+}
+
+static int
+uarb_mult_digit(uarb acc, int a_digits, uarb num, FIX_GCC int n_digits,
+ png_uint_16 val)
+ /* Primitive one-digit multiply - 'val' must be 0..65535. Note that this
+ * primitive is a multiply and accumulate - the result of *num * val is added
+ * to *acc.
+ *
+ * This is a one-digit multiply, so the product may be up to one digit longer
+ * than 'num', however the add to 'acc' means that the caller must ensure
+ * that 'acc' is at least one digit longer than this *and* at least one digit
+ * longer than the current length of 'acc'. (Or the caller must otherwise
+ * ensure 'adigits' is adequate from knowledge of the values.)
+ */
+{
+ /* The digits in *acc, *num and val are in the range 0..65535, so the
+ * result below is at most (65535*65535)+2*65635 = 65535*(65535+2), which is
+ * exactly 0xffffffff.
+ */
+ if (val > 0 && n_digits > 0) /* Else the product is 0 */
+ {
+ png_uint_32 carry = 0;
+ int out_digits = 0;
+
+ while (out_digits < n_digits || carry > 0)
+ {
+ if (out_digits < a_digits)
+ carry += acc[out_digits];
+
+ if (out_digits < n_digits)
+ carry += (png_uint_32)num[out_digits] * val;
+
+ acc[out_digits++] = (png_uint_16)(carry & 0xffff);
+ carry >>= 16;
+ }
+
+ /* So carry is 0 and all the input digits have been consumed. This means
+ * that it is possible to skip any remaining digits in acc.
+ */
+ if (out_digits > a_digits)
+ return out_digits;
+ }
+
+ return a_digits;
+}
+
+static int
+uarb_mult32(uarb acc, int a_digits, uarb num, int n_digits, png_uint_32 val)
+ /* calculate acc += num * val, 'val' may be any 32-bit value, 'acc' and 'num'
+ * may be any value, returns the number of digits in 'acc'.
+ */
+{
+ if (n_digits > 0 && val > 0)
+ {
+ a_digits = uarb_mult_digit(acc, a_digits, num, n_digits,
+ (png_uint_16)(val & 0xffff));
+
+ /* Because n_digits and val are >0 the following must be true: */
+ assert(a_digits > 0);
+
+ val >>= 16;
+ if (val > 0)
+ a_digits = uarb_mult_digit(acc+1, a_digits-1, num, n_digits,
+ (png_uint_16)val) + 1;
+ }
+
+ return a_digits;
+}
+
+static int
+uarb_shift(uarb inout, int ndigits, unsigned int right_shift)
+ /* Shift inout right by right_shift bits, right_shift must be in the range
+ * 1..15
+ */
+{
+ FIX_GCC int i = ndigits;
+ png_uint_16 carry = 0;
+
+ assert(right_shift >= 1 && right_shift <= 15);
+
+ while (--i >= 0)
+ {
+ png_uint_16 temp = (png_uint_16)(carry | (inout[i] >> right_shift));
+
+ /* Bottom bits to top bits of carry */
+ carry = (png_uint_16)((inout[i] << (16-right_shift)) & 0xffff);
+
+ inout[i] = temp;
+
+ /* The shift may reduce ndigits */
+ if (i == ndigits-1 && temp == 0)
+ ndigits = i;
+ }
+
+ return ndigits;
+}
+
+static int
+uarb_cmp(uarb a, int adigits, uarb b, int bdigits)
+ /* Return -1/0/+1 according as a<b/a==b/a>b */
+{
+ if (adigits < bdigits)
+ return -1;
+
+ if (adigits > bdigits)
+ return 1;
+
+ while (adigits-- > 0)
+ if (a[adigits] < b[adigits])
+ return -1;
+
+ else if (a[adigits] > b[adigits])
+ return 1;
+
+ return 0;
+}
+
+#if 0 /*UNUSED*/
+static int
+uarb_eq32(uarb num, int digits, png_uint_32 val)
+ /* Return true if the uarb is equal to 'val' */
+{
+ switch (digits)
+ {
+ case 0: return val == 0;
+ case 1: return val == num[0];
+ case 2: return (val & 0xffff) == num[0] && (val >> 16) == num[1];
+ default: return 0;
+ }
+}
+#endif
+
+static void
+uarb_printx(uarb num, int digits, FILE *out)
+ /* Print 'num' as a hexadecimal number (easier than decimal!) */
+{
+ while (digits > 0)
+ if (num[--digits] > 0)
+ {
+ fprintf(out, "0x%x", num[digits]);
+
+ while (digits > 0)
+ fprintf(out, "%.4x", num[--digits]);
+ }
+
+ else if (digits == 0) /* the number is 0 */
+ fputs("0x0", out);
+}
+
+static void
+uarb_print(uarb num, int digits, FILE *out)
+ /* Prints 'num' as a decimal if it will fit in an unsigned long, else as a
+ * hexadecimal number. Notice that the results vary for images over 4GByte
+ * in a system dependent way, and the hexadecimal form doesn't work very well
+ * in awk script input.
+ *
+ *
+ * TODO: write uarb_div10
+ */
+{
+ if (digits * sizeof (udigit) > sizeof (unsigned long))
+ uarb_printx(num, digits, out);
+
+ else
+ {
+ unsigned long n = 0;
+
+ while (digits > 0)
+ n = (n << 16) + num[--digits];
+
+ fprintf(out, "%lu", n);
+ }
+}
+
+/* Generate random bytes. This uses a boring repeatable algorithm and it
+ * is implemented here so that it gives the same set of numbers on every
+ * architecture. It's a linear congruential generator (Knuth or Sedgewick
+ * "Algorithms") but it comes from the 'feedback taps' table in Horowitz and
+ * Hill, "The Art of Electronics" (Pseudo-Random Bit Sequences and Noise
+ * Generation.)
+ *
+ * (Copied from contrib/libtests/pngvalid.c)
+ */
+static void
+make_random_bytes(png_uint_32* seed, void* pv, size_t size)
+{
+ png_uint_32 u0 = seed[0], u1 = seed[1];
+ png_bytep bytes = voidcast(png_bytep, pv);
+
+ /* There are thirty-three bits; the next bit in the sequence is bit-33 XOR
+ * bit-20. The top 1 bit is in u1, the bottom 32 are in u0.
+ */
+ size_t i;
+ for (i=0; i<size; ++i)
+ {
+ /* First generate 8 new bits then shift them in at the end. */
+ png_uint_32 u = ((u0 >> (20-8)) ^ ((u1 << 7) | (u0 >> (32-7)))) & 0xff;
+ u1 <<= 8;
+ u1 |= u0 >> 24;
+ u0 <<= 8;
+ u0 |= u;
+ *bytes++ = (png_byte)u;
+ }
+
+ seed[0] = u0;
+ seed[1] = u1;
+}
+
+/* Clear an object to a random value. */
+static void
+clear(void *pv, size_t size)
+{
+ static png_uint_32 clear_seed[2] = { 0x12345678, 0x9abcdef0 };
+ make_random_bytes(clear_seed, pv, size);
+}
+
+#define CLEAR(object) clear(&(object), sizeof (object))
+
+/* Copied from unreleased 1.7 code.
+ *
+ * CRC checking uses a local pre-built implementation of the Ethernet CRC32.
+ * This is to avoid a function call to the zlib DLL and to optimize the
+ * byte-by-byte case.
+ */
+static png_uint_32 crc_table[256] =
+{
+ 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,
+ 0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,
+ 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,
+ 0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
+ 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,
+ 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
+ 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,
+ 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
+ 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,
+ 0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,
+ 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,
+ 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
+ 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,
+ 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,
+ 0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,
+ 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
+ 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,
+ 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
+ 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,
+ 0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
+ 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,
+ 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,
+ 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,
+ 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
+ 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,
+ 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,
+ 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,
+ 0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
+ 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,
+ 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
+ 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,
+ 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
+ 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,
+ 0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,
+ 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,
+ 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
+ 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,
+ 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,
+ 0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,
+ 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
+ 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,
+ 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
+ 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,
+ 0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
+ 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,
+ 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,
+ 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,
+ 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
+ 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,
+ 0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,
+ 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,
+ 0x2d02ef8d
+};
+
+/* The CRC calculated here *IS* conditioned, the corresponding value used by
+ * zlib and the result value is obtained by XORing with CRC_INIT, which is also
+ * the first value that must be passed in (for the first byte) to crc_one_byte.
+ */
+#define CRC_INIT 0xffffffff
+
+static png_uint_32
+crc_one_byte(png_uint_32 crc, int b)
+{
+ return crc_table[(crc ^ b) & 0xff] ^ (crc >> 8);
+}
+
+static png_uint_32
+crc_init_4(png_uint_32 value)
+{
+ /* This is an alternative to the algorithm used in zlib, which requires four
+ * separate tables to parallelize the four byte operations, it only works for
+ * a CRC of the first four bytes of the stream, but this is what happens in
+ * the parser below where length+chunk-name is read and chunk-name used to
+ * initialize the CRC. Notice that the calculation here avoids repeated
+ * conditioning (xor with 0xffffffff) by storing the conditioned value.
+ */
+ png_uint_32 crc = crc_table[(~value >> 24)] ^ 0xffffff;
+
+ crc = crc_table[(crc ^ (value >> 16)) & 0xff] ^ (crc >> 8);
+ crc = crc_table[(crc ^ (value >> 8)) & 0xff] ^ (crc >> 8);
+ return crc_table[(crc ^ value) & 0xff] ^ (crc >> 8);
+}
+
+static int
+chunk_type_valid(png_uint_32 c)
+ /* Bit whacking approach to chunk name validation that is intended to avoid
+ * branches. The cost is that it uses a lot of 32-bit constants, which might
+ * be bad on some architectures.
+ */
+{
+ png_uint_32 t;
+
+ /* Remove bit 5 from all but the reserved byte; this means every
+ * 8-bit unit must be in the range 65-90 to be valid. So bit 5
+ * must be zero, bit 6 must be set and bit 7 zero.
+ */
+ c &= ~PNG_U32(32,32,0,32);
+ t = (c & ~0x1f1f1f1f) ^ 0x40404040;
+
+ /* Subtract 65 for each 8-bit quantity, this must not overflow
+ * and each byte must then be in the range 0-25.
+ */
+ c -= PNG_U32(65,65,65,65);
+ t |=c ;
+
+ /* Subtract 26, handling the overflow which should set the top
+ * three bits of each byte.
+ */
+ c -= PNG_U32(25,25,25,26);
+ t |= ~c;
+
+ return (t & 0xe0e0e0e0) == 0;
+}
+
+/**************************** CONTROL INFORMATION *****************************/
+
+/* Information about a sequence of IDAT chunks, the chunks have been re-synced
+ * using sync_stream below and the new lengths are recorded here. Because the
+ * number of chunks is unlimited this is handled using a linked list of these
+ * structures.
+ */
+struct IDAT_list
+{
+ struct IDAT_list *next; /* Linked list */
+ unsigned int length; /* Actual length of the array below */
+ unsigned int count; /* Number of entries that are valid */
+# define IDAT_INIT_LENGTH 16
+ png_uint_32 lengths[IDAT_INIT_LENGTH];
+};
+
+static void
+IDAT_list_init(struct IDAT_list *list)
+{
+ CLEAR(*list);
+
+ list->next = NULL;
+ list->length = IDAT_INIT_LENGTH;
+}
+
+static size_t
+IDAT_list_size(struct IDAT_list *list, unsigned int length)
+ /* Return the size in bytes of an IDAT_list of the given length. */
+{
+ if (list != NULL)
+ length = list->length;
+
+ return sizeof *list - sizeof list->lengths +
+ length * sizeof list->lengths[0];
+}
+
+static void
+IDAT_list_end(struct IDAT_list *IDAT_list)
+{
+ struct IDAT_list *list = IDAT_list->next;
+
+ CLEAR(*IDAT_list);
+
+ while (list != NULL)
+ {
+ struct IDAT_list *next = list->next;
+
+ clear(list, IDAT_list_size(list, 0));
+ free(list);
+ list = next;
+ }
+}
+
+static struct IDAT_list *
+IDAT_list_extend(struct IDAT_list *tail)
+{
+ /* Use the previous cached value if available. */
+ struct IDAT_list *next = tail->next;
+
+ if (next == NULL)
+ {
+ /* Insert a new, malloc'ed, block of IDAT information buffers, this
+ * one twice as large as the previous one:
+ */
+ unsigned int length = 2 * tail->length;
+
+ if (length < tail->length) /* arithmetic overflow */
+ length = tail->length;
+
+ next = voidcast(IDAT_list*, malloc(IDAT_list_size(NULL, length)));
+ CLEAR(*next);
+
+ /* The caller must handle this: */
+ if (next == NULL)
+ return NULL;
+
+ next->next = NULL;
+ next->length = length;
+ tail->next = next;
+ }
+
+ return next;
+}
+
+/* GLOBAL CONTROL STRUCTURE */
+struct global
+{
+ /* PUBLIC GLOBAL VARIABLES: OWNER INITIALIZE */
+ unsigned int errors :1; /* print file errors to stderr */
+ unsigned int warnings :1; /* print libpng warnings to stderr */
+ unsigned int optimize_zlib :1; /* Run optimization search */
+ unsigned int quiet :2; /* don't output summaries */
+ unsigned int verbose :3; /* various internal tracking */
+ unsigned int skip :3; /* Non-critical chunks to skip */
+# define SKIP_NONE 0
+# define SKIP_BAD_CRC 1 /* Chunks with a bad CRC */
+# define SKIP_UNSAFE 2 /* Chunks not safe to copy */
+# define SKIP_UNUSED 3 /* Chunks not used by libpng */
+# define SKIP_TRANSFORM 4 /* Chunks only used in transforms */
+# define SKIP_COLOR 5 /* Everything but tRNS, sBIT, gAMA and sRGB */
+# define SKIP_ALL 6 /* Everything but tRNS and sBIT */
+
+ png_uint_32 idat_max; /* 0 to perform no re-chunking */
+
+ int status_code; /* Accumulated status code */
+# define TOO_FAR_BACK 0x01 /* found a too-far-back error */
+# define CRC_ERROR 0x02 /* fixed an invalid CRC */
+# define STREAM_ERROR 0x04 /* damaged PNG stream (may be fixable) */
+# define TRUNCATED 0x08 /* truncated but still readable */
+# define FILE_ERROR 0x10 /* could not read the file */
+# define WRITE_ERROR 0x20 /* write error (this terminates the read) */
+# define INTERNAL_ERROR 0x40 /* internal limits/errors encountered */
+
+ /* PUBLIC GLOBAL VARIABLES: USED INTERNALLY BY IDAT READ CODE */
+ struct IDAT_list idat_cache; /* Cache of file IDAT information buffers */
+ /* The structure is shared across all uses of this global control
+ * structure to avoid reallocation between IDAT streams.
+ */
+};
+
+static int
+global_end(struct global *global)
+{
+
+ int rc;
+
+ IDAT_list_end(&global->idat_cache);
+ rc = global->status_code;
+ CLEAR(*global);
+ return rc;
+}
+
+static void
+global_init(struct global *global)
+ /* Call this once (and only once) to initialize the control */
+{
+ CLEAR(*global);
+
+ /* Globals */
+ global->errors = 0;
+ global->warnings = 0;
+ global->quiet = 0;
+ global->verbose = 0;
+ global->idat_max = 0; /* no re-chunking of IDAT */
+ global->optimize_zlib = 0;
+ global->skip = SKIP_NONE;
+ global->status_code = 0;
+
+ IDAT_list_init(&global->idat_cache);
+}
+
+static int
+skip_chunk_type(const struct global *global, png_uint_32 type)
+ /* Return true if this chunk is to be skipped according to the --strip
+ * option. This code needs to recognize all known ancillary chunks in order
+ * to handle the --strip=unsafe option.
+ */
+{
+ /* Never strip critical chunks: */
+ if (CRITICAL(type))
+ return 0;
+
+ switch (type)
+ {
+ /* Chunks that are treated as, effectively, critical because they affect
+ * correct interpretation of the pixel values:
+ */
+ case png_tRNS: case png_sBIT:
+ return 0;
+
+ /* Chunks that specify gamma encoding which should therefore only be
+ * removed the the user insists:
+ */
+ case png_gAMA: case png_sRGB:
+ if (global->skip >= SKIP_ALL)
+ return 1;
+ return 0;
+
+ /* Chunks that affect color interpretation - not used by libpng and rarely
+ * used by applications, but technically still required for correct
+ * interpretation of the image data:
+ */
+ case png_cHRM: case png_iCCP:
+ if (global->skip >= SKIP_COLOR)
+ return 1;
+ return 0;
+
+ /* Other chunks that are used by libpng in image transformations (as
+ * opposed to known chunks that have get/set APIs but are not otherwise
+ * used.)
+ */
+ case png_bKGD:
+ if (global->skip >= SKIP_TRANSFORM)
+ return 1;
+ return 0;
+
+ /* All other chunks that libpng knows about and affect neither image
+ * interpretation nor libpng transforms - chunks that are effectively
+ * unused by libpng even though libpng might recognize and store them.
+ */
+ case png_fRAc: case png_gIFg: case png_gIFt: case png_gIFx: case png_hIST:
+ case png_iTXt: case png_oFFs: case png_pCAL: case png_pHYs: case png_sCAL:
+ case png_sPLT: case png_sTER: case png_tEXt: case png_tIME: case png_zTXt:
+ if (global->skip >= SKIP_UNUSED)
+ return 1;
+ return 0;
+
+ /* Chunks that libpng does not know about (notice that this depends on the
+ * list above including all known chunks!) The decision here depends on
+ * whether the safe-to-copy bit is set in the chunk type.
+ */
+ default:
+ if (SAFE_TO_COPY(type))
+ {
+ if (global->skip >= SKIP_UNUSED) /* as above */
+ return 1;
+ }
+
+ else if (global->skip >= SKIP_UNSAFE)
+ return 1;
+
+ return 0;
+ }
+}
+
+/* PER-FILE CONTROL STRUCTURE */
+struct chunk;
+struct IDAT;
+struct file
+{
+ /* ANCESTORS */
+ struct global *global;
+
+ /* PUBLIC PER-FILE VARIABLES: CALLER INITIALIZE */
+ const char * file_name;
+ const char * out_name; /* Name of output file (if required) */
+
+ /* PUBLIC PER-FILE VARIABLES: SET BY PNG READ CODE */
+ /* File specific result codes */
+ int status_code; /* Set to a bit mask of the following: */
+ int read_errno; /* Records a read error errno */
+ int write_errno; /* Records a write error errno */
+
+ /* IHDR information */
+ png_uint_32 width;
+ png_uint_32 height;
+ png_byte bit_depth;
+ png_byte color_type;
+ png_byte compression_method;
+ png_byte filter_method;
+ png_byte interlace_method;
+
+ udigit image_bytes[5];
+ int image_digits;
+
+ /* PROTECTED PER-FILE VARIABLES: USED BY THE READ CODE */
+ FILE * file; /* Original PNG file */
+ FILE * out; /* If a new one is being written */
+ jmp_buf jmpbuf; /* Set while reading a PNG */
+
+ /* PROTECTED CHUNK SPECIFIC VARIABLES: USED BY CHUNK CODE */
+ /* The following variables are used during reading to record the length, type
+ * and data position of the *next* chunk or, right at the start, the
+ * signature (in length,type).
+ *
+ * When a chunk control structure is instantiated these values are copied
+ * into the structure and can then be overritten with the data for the next
+ * chunk.
+ */
+ fpos_t data_pos; /* Position of first byte of chunk data */
+ png_uint_32 length; /* First word (length or signature start) */
+ png_uint_32 type; /* Second word (type or signature end) */
+ png_uint_32 crc; /* Running chunk CRC (used by read_chunk) */
+
+ /* These counts are maintained by the read and write routines below and are
+ * reset by the chunk handling code. They record the total number of bytes
+ * read or written for the chunk, including the header (length,type) bytes.
+ */
+ png_uint_32 read_count; /* Count of bytes read (in the chunk) */
+ png_uint_32 write_count; /* Count of bytes written (in the chunk) */
+ int state; /* As defined here: */
+# define STATE_SIGNATURE 0 /* The signature is being written */
+# define STATE_CHUNKS 1 /* Non-IDAT chunks are being written */
+# define STATE_IDAT 2 /* An IDAT stream is being written */
+
+ /* Two pointers used to enable clean-up in the event of fatal errors and to
+ * hold state about the parser process (only one of each at present.)
+ */
+ struct chunk * chunk;
+ struct IDAT * idat;
+
+ /* Interface to allocate a new chunk or IDAT control structure. The result
+ * is returned by setting one or other of the above variables. Note that the
+ * relevant initializer is called by the allocator function. The alloc_ptr
+ * is used only by the implementation of the allocate function.
+ */
+ void * alloc_ptr;
+ void (*alloc)(struct file*,int idat);
+ /* idat: allocate IDAT not chunk */
+};
+
+/* Valid longjmp (stop) codes are: */
+#define LIBPNG_WARNING_CODE 1 /* generic png_error */
+#define LIBPNG_ERROR_CODE 2 /* generic png_error */
+#define ZLIB_ERROR_CODE 3 /* generic zlib error */
+#define INVALID_ERROR_CODE 4 /* detected an invalid PNG */
+#define READ_ERROR_CODE 5 /* read failed */
+#define WRITE_ERROR_CODE 6 /* error in write */
+#define UNEXPECTED_ERROR_CODE 7 /* unexpected (internal?) error */
+
+static void
+emit_string(const char *str, FILE *out)
+ /* Print a string with spaces replaced by '_' and non-printing characters by
+ * an octal escape.
+ */
+{
+ for (; *str; ++str)
+ if (isgraph(UCHAR_MAX & *str))
+ putc(*str, out);
+
+ else if (isspace(UCHAR_MAX & *str))
+ putc('_', out);
+
+ else
+ fprintf(out, "\\%.3o", *str);
+}
+
+static const char *
+strcode(int code)
+{
+ switch (code)
+ {
+ case LIBPNG_WARNING_CODE: return "warning";
+ case LIBPNG_ERROR_CODE: return "libpng";
+ case ZLIB_ERROR_CODE: return "zlib";
+ case INVALID_ERROR_CODE: return "invalid";
+ case READ_ERROR_CODE: return "read";
+ case WRITE_ERROR_CODE: return "write";
+ case UNEXPECTED_ERROR_CODE: return "unexpected";
+ default: return "INVALID";
+ }
+}
+
+static void
+emit_error(struct file *file, int code, const char *what)
+ /* Generic error message routine, takes a 'stop' code but can be used
+ * elsewhere. Always outputs a message.
+ */
+{
+ const char *reason;
+ int err = 0;
+
+ switch (code)
+ {
+ case LIBPNG_WARNING_CODE: reason = "libpng warning:"; break;
+ case LIBPNG_ERROR_CODE: reason = "libpng error:"; break;
+ case ZLIB_ERROR_CODE: reason = "zlib error:"; break;
+ case INVALID_ERROR_CODE: reason = "invalid"; break;
+ case READ_ERROR_CODE: reason = "read failure:";
+ err = file->read_errno;
+ break;
+ case WRITE_ERROR_CODE: reason = "write error";
+ err = file->write_errno;
+ break;
+ case UNEXPECTED_ERROR_CODE: reason = "unexpected error:";
+ err = file->read_errno;
+ if (err == 0)
+ err = file->write_errno;
+ break;
+ default: reason = "INVALID (internal error):"; break;
+ }
+
+ if (err != 0)
+ fprintf(stderr, "%s: %s %s [%s]\n", file->file_name, reason, what,
+ strerror(err));
+
+ else
+ fprintf(stderr, "%s: %s %s\n", file->file_name, reason, what);
+}
+
+static void chunk_end(struct chunk **);
+static void IDAT_end(struct IDAT **);
+
+static int
+file_end(struct file *file)
+{
+ int rc;
+
+ /* If either of the chunk pointers are set end them here, the IDAT structure
+ * must be deallocated first as it may deallocate the chunk structure.
+ */
+ if (file->idat != NULL)
+ IDAT_end(&file->idat);
+
+ if (file->chunk != NULL)
+ chunk_end(&file->chunk);
+
+ rc = file->status_code;
+
+ if (file->file != NULL)
+ (void)fclose(file->file);
+
+ if (file->out != NULL)
+ {
+ /* NOTE: this is bitwise |, all the following functions must execute and
+ * must succeed.
+ */
+ if (ferror(file->out) | fflush(file->out) | fclose(file->out))
+ {
+ perror(file->out_name);
+ emit_error(file, READ_ERROR_CODE, "output write error");
+ rc |= WRITE_ERROR;
+ }
+ }
+
+ /* Accumulate the result codes */
+ file->global->status_code |= rc;
+
+ CLEAR(*file);
+
+ return rc; /* status code: non-zero on read or write error */
+}
+
+static int
+file_init(struct file *file, struct global *global, const char *file_name,
+ const char *out_name, void *alloc_ptr, void (*alloc)(struct file*,int))
+ /* Initialize a file control structure. This will open the given files as
+ * well. The status code returned is 0 on success, non zero (using the flags
+ * above) on a file open error.
+ */
+{
+ CLEAR(*file);
+ file->global = global;
+
+ file->file_name = file_name;
+ file->out_name = out_name;
+ file->status_code = 0;
+ file->read_errno = 0;
+ file->write_errno = 0;
+
+ file->file = NULL;
+ file->out = NULL;
+ /* jmpbuf is garbage: must be set by read_png */
+
+ file->read_count = 0;
+ file->state = STATE_SIGNATURE;
+
+ file->chunk = NULL;
+ file->idat = NULL;
+
+ file->alloc_ptr = alloc_ptr;
+ file->alloc = alloc;
+
+ /* Open the files: */
+ assert(file_name != NULL);
+ file->file = fopen(file_name, "rb");
+
+ if (file->file == NULL)
+ {
+ file->read_errno = errno;
+ file->status_code |= FILE_ERROR;
+ /* Always output: please give a readable file! */
+ perror(file_name);
+ return FILE_ERROR;
+ }
+
+ if (out_name != NULL)
+ {
+ file->out = fopen(out_name, "wb");
+
+ if (file->out == NULL)
+ {
+ file->write_errno = errno;
+ file->status_code |= WRITE_ERROR;
+ perror(out_name);
+ return WRITE_ERROR;
+ }
+ }
+
+ return 0;
+}
+
+static void
+log_error(struct file *file, int code, const char *what)
+ /* Like emit_error but checks the global 'errors' flag */
+{
+ if (file->global->errors)
+ emit_error(file, code, what);
+}
+
+static char
+type_char(png_uint_32 v)
+{
+ /* In fact because chunk::chunk_type is validated prior to any call to this
+ * function it will always return a-zA-Z, but the extra codes are just there
+ * to help in finding internal (programming) errors. Note that the code only
+ * ever considers the low 7 bits of the value (so it is not necessary for the
+ * type_name function to mask of the byte.)
+ */
+ if (v & 32)
+ return "!abcdefghijklmnopqrstuvwxyz56789"[(v-96)&31];
+
+ else
+ return "@ABCDEFGHIJKLMNOPQRSTUVWXYZ01234"[(v-64)&31];
+}
+
+static void
+type_name(png_uint_32 type, FILE *out)
+{
+ putc(type_char(type >> 24), out);
+ putc(type_char(type >> 16), out);
+ putc(type_char(type >> 8), out);
+ putc(type_char(type ), out);
+}
+
+static void
+type_sep(FILE *out)
+{
+ putc(':', out);
+ putc(' ', out);
+}
+
+static png_uint_32 current_type(struct file *file, int code);
+
+PNG_NORETURN static void
+stop(struct file *file, int code, const char *what)
+ /* Return control when a PNG file cannot be read. This outputs an 'ERR'
+ * summary line too.
+ */
+{
+ log_error(file, code, what);
+
+ /* The chunk being read is typically identified by file->chunk or, if this is
+ * NULL, by file->type. This may be wrong if libpng reads ahead, but this
+ * only happens with IDAT where libpng reads the header then jumps around
+ * finding errors in the previous chunks. We know that is happening because
+ * we are at the start of the IDAT (i.e. no IDAT data has yet been written.)
+ *
+ * SUMMARY FORMAT (stop):
+ *
+ * IDAT ERR status code read-errno write-errno message file
+ *
+ * 'uncompressed' will be 0 if there was a problem in the IHDR. The errno
+ * values are emit_string(strerror(errno)).
+ */
+ if (file->global->quiet < 2) /* need two quiets to stop this. */
+ {
+ png_uint_32 type;
+
+ if (file->chunk != NULL)
+ type = current_type(file, code); /* Gropes in struct chunk and IDAT */
+
+ else
+ type = file->type;
+
+ if (type)
+ type_name(type, stdout);
+
+ else /* magic: an IDAT header, produces bogons for too many IDATs */
+ fputs("HEAD", stdout); /* not a registered chunk! */
+
+ printf(" ERR %.2x %s ", file->status_code, strcode(code));
+ /* This only works one strerror at a time, because of the way strerror is
+ * implemented.
+ */
+ emit_string(strerror(file->read_errno), stdout);
+ putc(' ', stdout);
+ emit_string(strerror(file->write_errno), stdout);
+ putc(' ', stdout);
+ emit_string(what, stdout);
+ putc(' ', stdout);
+ fputs(file->file_name, stdout);
+ putc('\n', stdout);
+ }
+
+ file->status_code |= FILE_ERROR;
+ longjmp(file->jmpbuf, code);
+}
+
+PNG_NORETURN static void
+stop_invalid(struct file *file, const char *what)
+{
+ stop(file, INVALID_ERROR_CODE, what);
+}
+
+static void
+type_message(struct file *file, png_uint_32 type, const char *what)
+ /* Error message for a chunk; the chunk name comes from 'type' */
+{
+ if (file->global->errors)
+ {
+ fputs(file->file_name, stderr);
+ type_sep(stderr);
+ type_name(type, stderr);
+ type_sep(stderr);
+ fputs(what, stderr);
+ putc('\n', stderr);
+ }
+}
+
+/* Input file positioning - we jump around in the input file while reading
+ * stuff, these wrappers deal with the error handling.
+ */
+static void
+file_getpos(struct file *file, fpos_t *pos)
+{
+ if (fgetpos(file->file, pos))
+ {
+ /* This is unexpected, so perror it */
+ perror(file->file_name);
+ stop(file, READ_ERROR_CODE, "fgetpos");
+ }
+}
+
+static void
+file_setpos(struct file *file, const fpos_t *pos)
+{
+ if (fsetpos(file->file, pos))
+ {
+ perror(file->file_name);
+ stop(file, READ_ERROR_CODE, "fsetpos");
+ }
+}
+
+static void
+getpos(struct file *file)
+ /* Get the current position and store it in 'data_pos'. The corresponding
+ * setpos() function is chunk specific because it uses the copy of the
+ * position for the specific chunk.
+ */
+{
+ file_getpos(file, &file->data_pos);
+}
+
+
+/* Read utility - read a single byte, returns a value in the range 0..255 or EOF
+ * on a read error. In the latter case status_code and read_errno are updated
+ * appropriately.
+ */
+static int
+read_byte(struct file *file)
+{
+ int ch = getc(file->file);
+
+ if (ch >= 0 && ch <= 255)
+ {
+ ++(file->read_count);
+ return ch;
+ }
+
+ else if (ch != EOF)
+ {
+ file->status_code |= INTERNAL_ERROR;
+ file->read_errno = ERANGE; /* out of range character */
+
+ /* This is very unexpected; an error message is always output: */
+ emit_error(file, UNEXPECTED_ERROR_CODE, "file read");
+ }
+
+# ifdef EINTR
+ else if (errno == EINTR) /* Interrupted, try again */
+ {
+ errno = 0;
+ return read_byte(file);
+ }
+# endif
+
+ else
+ {
+ /* An error, it doesn't really matter what the error is but it gets
+ * recorded anyway.
+ */
+ if (ferror(file->file))
+ file->read_errno = errno;
+
+ else if (feof(file->file))
+ file->read_errno = 0; /* I.e. a regular EOF, no error */
+
+ else /* unexpected */
+ file->read_errno = EDOM;
+ }
+
+ /* 'TRUNCATED' is used for all cases of failure to read a byte, because of
+ * the way libpng works a byte read is never attempted unless the byte is
+ * expected to be there, so EOF should not occur.
+ */
+ file->status_code |= TRUNCATED;
+ return EOF;
+}
+
+static png_byte
+reread_byte(struct file *file)
+ /* Read a byte when an error is not expected to happen because the byte has
+ * been read before without error.
+ */
+{
+ int ch = getc(file->file);
+
+ if (errno != 0)
+ file->read_errno = errno;
+
+ if (ch < 0 || ch > 255)
+ stop(file, UNEXPECTED_ERROR_CODE, "reread");
+
+ return (png_byte)ch;
+}
+
+static png_uint_32
+reread_4(struct file *file)
+ /* The same but for a four byte quantity */
+{
+ png_uint_32 result = 0;
+ int i = 0;
+
+ while (++i <= 4)
+ result = (result << 8) + reread_byte(file);
+
+ return result;
+}
+
+static void
+skip_12(struct file *file)
+ /* Skip exactly 12 bytes in the input stream - used to skip a CRC and chunk
+ * header that has been read before.
+ */
+{
+ /* Since the chunks were read before this shouldn't fail: */
+ if (fseek(file->file, 12, SEEK_CUR) != 0)
+ {
+ if (errno != 0)
+ file->read_errno = errno;
+
+ stop(file, UNEXPECTED_ERROR_CODE, "reskip");
+ }
+}
+
+static void
+write_byte(struct file *file, int b)
+ /* Write one byte to the output - this causes a fatal error if the write
+ * fails and the read of this PNG file immediately terminates. Just
+ * increments the write count if there is no output file.
+ */
+{
+ if (file->out != NULL)
+ {
+ if (putc(b, file->out) != b)
+ {
+ file->write_errno = errno;
+ file->status_code |= WRITE_ERROR;
+ stop(file, WRITE_ERROR_CODE, "write byte");
+ }
+ }
+
+ ++(file->write_count);
+}
+
+/* Derivatives of the read/write functions. */
+static unsigned int
+read_4(struct file *file, png_uint_32 *pu)
+ /* Read four bytes, returns the number of bytes read successfully and, if all
+ * four bytes are read, assigns the result to *pu.
+ */
+{
+ unsigned int i = 0;
+ png_uint_32 val = 0;
+
+ do
+ {
+ int ch = read_byte(file);
+
+ if (ch == EOF)
+ return i;
+
+ val = (val << 8) + ch;
+ } while (++i < 4);
+
+ *pu = val;
+ return i;
+}
+
+/* CRC handling - read but calculate the CRC while doing so. */
+static int
+crc_read_many(struct file *file, png_uint_32 length)
+ /* Reads 'length' bytes and updates the CRC, returns true on success, false
+ * if the input is truncated.
+ */
+{
+ if (length > 0)
+ {
+ png_uint_32 crc = file->crc;
+
+ do
+ {
+ int ch = read_byte(file);
+
+ if (ch == EOF)
+ return 0; /* Truncated */
+
+ crc = crc_one_byte(crc, ch);
+ }
+ while (--length > 0);
+
+ file->crc = crc;
+ }
+
+ return 1; /* OK */
+}
+
+static int
+calc_image_size(struct file *file)
+ /* Fill in the image_bytes field given the IHDR information, calls stop on
+ * error.
+ */
+{
+ png_uint_16 pd = file->bit_depth;
+
+ switch (file->color_type)
+ {
+ default:
+ stop_invalid(file, "IHDR: colour type");
+
+ invalid_bit_depth:
+ stop_invalid(file, "IHDR: bit depth");
+
+ case 0: /* g */
+ if (pd != 1 && pd != 2 && pd != 4 && pd != 8 && pd != 16)
+ goto invalid_bit_depth;
+ break;
+
+ case 3:
+ if (pd != 1 && pd != 2 && pd != 4 && pd != 8)
+ goto invalid_bit_depth;
+ break;
+
+ case 2: /* rgb */
+ if (pd != 8 && pd != 16)
+ goto invalid_bit_depth;
+
+ pd = (png_uint_16)(pd * 3);
+ break;
+
+ case 4: /* ga */
+ if (pd != 8 && pd != 16)
+ goto invalid_bit_depth;
+
+ pd = (png_uint_16)(pd * 2);
+ break;
+
+ case 6: /* rgba */
+ if (pd != 8 && pd != 16)
+ goto invalid_bit_depth;
+
+ pd = (png_uint_16)(pd * 4);
+ break;
+ }
+
+ if (file->width < 1 || file->width > 0x7fffffff)
+ stop_invalid(file, "IHDR: width");
+
+ else if (file->height < 1 || file->height > 0x7fffffff)
+ stop_invalid(file, "IHDR: height");
+
+ else if (file->compression_method != 0)
+ stop_invalid(file, "IHDR: compression method");
+
+ else if (file->filter_method != 0)
+ stop_invalid(file, "IHDR: filter method");
+
+ else switch (file->interlace_method)
+ {
+ case PNG_INTERLACE_ADAM7:
+ /* Interlacing makes the image larger because of the replication of
+ * both the filter byte and the padding to a byte boundary.
+ */
+ {
+ int pass;
+ int image_digits = 0;
+ udigit row_width[2], row_bytes[3];
+
+ for (pass=0; pass<=6; ++pass)
+ {
+ png_uint_32 pw = PNG_PASS_COLS(file->width, pass);
+
+ if (pw > 0)
+ {
+ int digits;
+
+ /* calculate 1+((pw*pd+7)>>3) in row_bytes */
+ digits = uarb_mult_digit(row_bytes, uarb_set(row_bytes, 7),
+ row_width, uarb_set(row_width, pw), pd);
+ digits = uarb_shift(row_bytes, digits, 3);
+ digits = uarb_inc(row_bytes, digits, 1);
+
+ /* Add row_bytes * pass-height to the file image_bytes field
+ */
+ image_digits = uarb_mult32(file->image_bytes, image_digits,
+ row_bytes, digits,
+ PNG_PASS_ROWS(file->height, pass));
+ }
+ }
+
+ file->image_digits = image_digits;
+ }
+ break;
+
+ case PNG_INTERLACE_NONE:
+ {
+ int digits;
+ udigit row_width[2], row_bytes[3];
+
+ /* As above, but use image_width in place of the pass width: */
+ digits = uarb_mult_digit(row_bytes, uarb_set(row_bytes, 7),
+ row_width, uarb_set(row_width, file->width), pd);
+ digits = uarb_shift(row_bytes, digits, 3);
+ digits = uarb_inc(row_bytes, digits, 1);
+
+ /* Set row_bytes * image-height to the file image_bytes field */
+ file->image_digits = uarb_mult32(file->image_bytes, 0,
+ row_bytes, digits, file->height);
+ }
+ break;
+
+ default:
+ stop_invalid(file, "IHDR: interlace method");
+ }
+
+ assert(file->image_digits >= 1 && file->image_digits <= 5);
+ return 1;
+}
+
+/* PER-CHUNK CONTROL STRUCTURE
+ * This structure is instantiated for each chunk, except for the IDAT chunks
+ * where one chunk control structure is used for the whole of a single stream of
+ * IDAT chunks (see the IDAT control structure below).
+ */
+struct chunk
+{
+ /* ANCESTORS */
+ struct file * file;
+ struct global * global;
+
+ /* PUBLIC IDAT INFORMATION: SET BY THE ZLIB CODE */
+ udigit uncompressed_bytes[5];
+ int uncompressed_digits;
+ udigit compressed_bytes[5];
+ int compressed_digits;
+
+ /* PUBLIC PER-CHUNK INFORMATION: USED BY CHUNK READ CODE */
+ /* This information is filled in by chunk_init from the data in the file
+ * control structure, but chunk_length may be changed later.
+ */
+ fpos_t chunk_data_pos; /* Position of first byte of chunk data */
+ png_uint_32 chunk_length; /* From header (or modified below) */
+ png_uint_32 chunk_type; /* From header */
+
+ /* PUBLIC PER-CHUNK INFORMATION: FOR THE CHUNK WRITE CODE */
+ png_uint_32 write_crc; /* Output CRC (may differ from read_crc) */
+ png_uint_32 rewrite_offset; /* Count of bytes before rewrite. */
+ int rewrite_length; /* Number of bytes left to change */
+ png_byte rewrite_buffer[2]; /* Buffer of new byte values */
+};
+
+static void
+chunk_message(struct chunk *chunk, const char *message)
+{
+ type_message(chunk->file, chunk->chunk_type, message);
+}
+
+static void
+chunk_end(struct chunk **chunk_var)
+{
+ struct chunk *chunk = *chunk_var;
+
+ *chunk_var = NULL;
+ CLEAR(*chunk);
+}
+
+static void
+chunk_init(struct chunk * const chunk, struct file * const file)
+ /* When a chunk is initialized the file length/type/pos are copied into the
+ * corresponding chunk fields and the new chunk is registered in the file
+ * structure. There can only be one chunk at a time.
+ *
+ * NOTE: this routine must onely be called from the file alloc routine!
+ */
+{
+ assert(file->chunk == NULL);
+
+ CLEAR(*chunk);
+
+ chunk->file = file;
+ chunk->global = file->global;
+
+ chunk->chunk_data_pos = file->data_pos;
+ chunk->chunk_length = file->length;
+ chunk->chunk_type = file->type;
+
+ /* Compresssed/uncompressed size information (from the zlib control structure
+ * that is used to check the compressed data in a chunk.)
+ */
+ chunk->uncompressed_digits = 0;
+ chunk->compressed_digits = 0;
+
+ file->chunk = chunk;
+}
+
+static png_uint_32
+current_type(struct file *file, int code)
+ /* Guess the actual chunk type that causes a stop() */
+{
+ /* This may return png_IDAT for errors detected (late) in the header; that
+ * includes any inter-chunk consistency check that libpng performs. Assume
+ * that if the chunk_type is png_IDAT and the file write count is 8 this is
+ * what is happening.
+ */
+ if (file->chunk != NULL)
+ {
+ png_uint_32 type = file->chunk->chunk_type;
+
+ /* This is probably wrong for the excess IDATs case, because then libpng
+ * whines about too many of them (apparently in some cases erroneously)
+ * when the header is read.
+ */
+ if (code <= LIBPNG_ERROR_CODE && type == png_IDAT &&
+ file->write_count == 8)
+ type = 0; /* magic */
+
+ return type;
+ }
+
+ else
+ return file->type;
+}
+
+static void
+setpos(struct chunk *chunk)
+ /* Reset the position to 'chunk_data_pos' - the start of the data for this
+ * chunk. As a side effect the read_count in the file is reset to 8, just
+ * after the length/type header.
+ */
+{
+ chunk->file->read_count = 8;
+ file_setpos(chunk->file, &chunk->chunk_data_pos);
+}
+
+/* Specific chunk handling - called for each chunk header, all special chunk
+ * processing is initiated in these functions.
+ */
+/* The next functions handle special processing for those chunks with LZ data,
+ * the data is identified and checked for validity. If there are problems which
+ * cannot be corrected the routines return false, otherwise true (although
+ * modification to the zlib header may be required.)
+ *
+ * The compressed data is in zlib format (RFC1950) and consequently has a
+ * minimum length of 7 bytes.
+ */
+static int zlib_check(struct file *file, png_uint_32 offset);
+
+static int
+process_zTXt_iCCP(struct file *file)
+ /* zTXt and iCCP have exactly the same form - keyword, null, compression
+ * method then compressed data.
+ */
+{
+ struct chunk *chunk = file->chunk;
+ png_uint_32 length;
+ png_uint_32 index = 0;
+
+ assert(chunk != NULL && file->idat == NULL);
+ length = chunk->chunk_length;
+ setpos(chunk);
+
+ while (length >= 9)
+ {
+ --length;
+ ++index;
+ if (reread_byte(file) == 0) /* keyword null terminator */
+ {
+ --length;
+ ++index;
+ (void)reread_byte(file); /* compression method */
+ return zlib_check(file, index);
+ }
+ }
+
+ chunk_message(chunk, "too short");
+ return 0; /* skip */
+}
+
+static int
+process_iTXt(struct file *file)
+{
+ /* Like zTXt but more fields. */
+ struct chunk *chunk = file->chunk;
+ png_uint_32 length;
+ png_uint_32 index = 0;
+
+ assert(chunk != NULL && file->idat == NULL);
+ length = chunk->chunk_length;
+ setpos(chunk);
+
+ while (length >= 5)
+ {
+ --length;
+ ++index;
+ if (reread_byte(file) == 0) /* keyword null terminator */
+ {
+ --length;
+ ++index;
+ if (reread_byte(file) == 0) /* uncompressed text */
+ return 1; /* nothing to check */
+
+ --length;
+ ++index;
+ (void)reread_byte(file); /* compression method */
+
+ /* Skip the language tag (null terminated). */
+ while (length >= 9)
+ {
+ --length;
+ ++index;
+ if (reread_byte(file) == 0) /* terminator */
+ {
+ /* Skip the translated keyword */
+ while (length >= 8)
+ {
+ --length;
+ ++index;
+ if (reread_byte(file) == 0) /* terminator */
+ return zlib_check(file, index);
+ }
+ }
+ }
+
+ /* Ran out of bytes in the compressed case. */
+ break;
+ }
+ }
+
+ log_error(file, INVALID_ERROR_CODE, "iTXt chunk length");
+
+ return 0; /* skip */
+}
+
+/* IDAT READ/WRITE CONTROL STRUCTURE */
+struct IDAT
+{
+ /* ANCESTORS */
+ struct file * file;
+ struct global * global;
+
+ /* PROTECTED IDAT INFORMATION: SET BY THE IDAT READ CODE */
+ struct IDAT_list *idat_list_head; /* START of the list of IDAT information */
+ struct IDAT_list *idat_list_tail; /* *END* of the list of IDAT information */
+
+ /* PROTECTED IDAT INFORMATION: USED BY THE IDAT WRITE CODE */
+ struct IDAT_list *idat_cur; /* Current list entry */
+ unsigned int idat_count; /* And the *current* index into the list */
+ png_uint_32 idat_index; /* Index of *next* input byte to write */
+ png_uint_32 idat_length; /* Cache of current chunk length */
+};
+
+/* NOTE: there is currently no IDAT_reset, so a stream cannot contain more than
+ * one IDAT sequence (i.e. MNG is not supported).
+ */
+
+static void
+IDAT_end(struct IDAT **idat_var)
+{
+ struct IDAT *idat = *idat_var;
+ struct file *file = idat->file;
+
+ *idat_var = NULL;
+
+ CLEAR(*idat);
+
+ assert(file->chunk != NULL);
+ chunk_end(&file->chunk);
+
+ /* Regardless of why the IDAT was killed set the state back to CHUNKS (it may
+ * already be CHUNKS because the state isn't changed until process_IDAT
+ * returns; a stop will cause IDAT_end to be entered in state CHUNKS!)
+ */
+ file->state = STATE_CHUNKS;
+}
+
+static void
+IDAT_init(struct IDAT * const idat, struct file * const file)
+ /* When the chunk is png_IDAT instantiate an IDAT control structure in place
+ * of a chunk control structure. The IDAT will instantiate a chunk control
+ * structure using the file alloc routine.
+ *
+ * NOTE: this routine must only be called from the file alloc routine!
+ */
+{
+ assert(file->chunk == NULL);
+ assert(file->idat == NULL);
+
+ CLEAR(*idat);
+
+ idat->file = file;
+ idat->global = file->global;
+
+ /* Initialize the tail to the pre-allocated buffer and set the count to 0
+ * (empty.)
+ */
+ idat->global->idat_cache.count = 0;
+ idat->idat_list_head = idat->idat_list_tail = &idat->global->idat_cache;
+
+ /* Now the chunk. The allocator calls the initializer of the new chunk and
+ * stores the result in file->chunk:
+ */
+ file->alloc(file, 0/*chunk*/);
+ assert(file->chunk != NULL);
+
+ /* And store this for cleanup (and to check for double alloc or failure to
+ * free.)
+ */
+ file->idat = idat;
+}
+
+static png_uint_32
+rechunk_length(struct IDAT *idat)
+ /* Return the length for the next IDAT chunk, taking into account
+ * rechunking.
+ */
+{
+ png_uint_32 len = idat->global->idat_max;
+
+ if (len == 0) /* use original chunk lengths */
+ {
+ const struct IDAT_list *cur;
+ unsigned int count;
+
+ if (idat->idat_index == 0) /* at the new chunk (first time) */
+ return idat->idat_length; /* use the cache */
+
+ /* Otherwise rechunk_length is called at the end of a chunk for the length
+ * of the next one.
+ */
+ cur = idat->idat_cur;
+ count = idat->idat_count;
+
+ assert(idat->idat_index == idat->idat_length &&
+ idat->idat_length == cur->lengths[count]);
+
+ /* Return length of the *next* chunk */
+ if (++count < cur->count)
+ return cur->lengths[count];
+
+ /* End of this list */
+ assert(cur != idat->idat_list_tail);
+ cur = cur->next;
+ assert(cur != NULL && cur->count > 0);
+ return cur->lengths[0];
+ }
+
+ else /* rechunking */
+ {
+ /* The chunk size is the lesser of file->idat_max and the number
+ * of remaining bytes.
+ */
+ png_uint_32 have = idat->idat_length - idat->idat_index;
+
+ if (len > have)
+ {
+ struct IDAT_list *cur = idat->idat_cur;
+ unsigned int j = idat->idat_count+1; /* the next IDAT in the list */
+
+ do
+ {
+ /* Add up the remaining bytes. This can't overflow because the
+ * individual lengths are always <= 0x7fffffff, so when we add two
+ * of them overflow is not possible.
+ */
+ assert(cur != NULL);
+
+ for (;;)
+ {
+ /* NOTE: IDAT_list::count here, not IDAT_list::length */
+ for (; j < cur->count; ++j)
+ {
+ have += cur->lengths[j];
+ if (len <= have)
+ return len;
+ }
+
+ /* If this was the end return the count of the available bytes */
+ if (cur == idat->idat_list_tail)
+ return have;
+
+ cur = cur->next;
+ j = 0;
+ }
+ }
+ while (len > have);
+ }
+
+ return len;
+ }
+}
+
+static int
+process_IDAT(struct file *file)
+ /* Process the IDAT stream, this is the more complex than the preceding
+ * cases because the compressed data is spread across multiple IDAT chunks
+ * (typically). Rechunking of the data is not handled here; all this
+ * function does is establish whether the zlib header needs to be modified.
+ *
+ * Initially the function returns false, indicating that the chunk should not
+ * be written. It does this until the last IDAT chunk is passed in, then it
+ * checks the zlib data and returns true.
+ *
+ * It does not return false on a fatal error; it calls stop instead.
+ *
+ * The caller must have an instantiated (IDAT) control structure and it must
+ * have extent over the whole read of the IDAT stream. For a PNG this means
+ * the whole PNG read, for MNG it could have lesser extent.
+ */
+{
+ struct IDAT_list *list;
+
+ assert(file->idat != NULL && file->chunk != NULL);
+
+ /* We need to first check the entire sequence of IDAT chunks to ensure the
+ * stream is in sync. Do this by building a list of all the chunks and
+ * recording the length of each because the length may have been fixed up by
+ * sync_stream below.
+ *
+ * At the end of the list of chunks, where the type of the next chunk is not
+ * png_IDAT, process the whole stream using the list data to check validity
+ * then return control to the start and rewrite everything.
+ */
+ list = file->idat->idat_list_tail;
+
+ if (list->count == list->length)
+ {
+ list = IDAT_list_extend(list);
+
+ if (list == NULL)
+ stop(file, READ_ERROR_CODE, "out of memory");
+
+ /* Move to the next block */
+ list->count = 0;
+ file->idat->idat_list_tail = list;
+ }
+
+ /* And fill in the next IDAT information buffer. */
+ list->lengths[(list->count)++] = file->chunk->chunk_length;
+
+ /* The type of the next chunk was recorded in the file control structure by
+ * the caller, if this is png_IDAT return 'skip' to the caller.
+ */
+ if (file->type == png_IDAT)
+ return 0; /* skip this for the moment */
+
+ /* This is the final IDAT chunk, so run the tests to check for the too far
+ * back error and possibly optimize the window bits. This means going back
+ * to the start of the first chunk data, which is stored in the original
+ * chunk allocation.
+ */
+ setpos(file->chunk);
+
+ if (zlib_check(file, 0))
+ {
+ struct IDAT *idat;
+ int cmp;
+
+ /* The IDAT stream was successfully uncompressed; see whether it
+ * contained the correct number of bytes of image data.
+ */
+ cmp = uarb_cmp(file->image_bytes, file->image_digits,
+ file->chunk->uncompressed_bytes, file->chunk->uncompressed_digits);
+
+ if (cmp < 0)
+ type_message(file, png_IDAT, "extra uncompressed data");
+
+ else if (cmp > 0)
+ stop(file, LIBPNG_ERROR_CODE, "IDAT: uncompressed data too small");
+
+ /* Return the stream to the start of the first IDAT chunk; the length
+ * is set in the write case below but the input chunk variables must be
+ * set (once) here:
+ */
+ setpos(file->chunk);
+
+ idat = file->idat;
+ idat->idat_cur = idat->idat_list_head;
+ idat->idat_length = idat->idat_cur->lengths[0];
+ idat->idat_count = 0; /* Count of chunks read in current list */
+ idat->idat_index = 0; /* Index into chunk data */
+
+ /* Update the chunk length to the correct value for the IDAT chunk: */
+ file->chunk->chunk_length = rechunk_length(idat);
+
+ /* Change the state to writing IDAT chunks */
+ file->state = STATE_IDAT;
+
+ return 1;
+ }
+
+ else /* Failure to decompress the IDAT stream; give up. */
+ stop(file, ZLIB_ERROR_CODE, "could not uncompress IDAT");
+}
+
+/* ZLIB CONTROL STRUCTURE */
+struct zlib
+{
+ /* ANCESTORS */
+ struct IDAT * idat; /* NOTE: May be NULL */
+ struct chunk * chunk;
+ struct file * file;
+ struct global *global;
+
+ /* GLOBAL ZLIB INFORMATION: SET BY THE CALLER */
+ png_uint_32 rewrite_offset;
+
+ /* GLOBAL ZLIB INFORMATION: SET BY THE ZLIB READ CODE */
+ udigit compressed_bytes[5];
+ int compressed_digits;
+ udigit uncompressed_bytes[5];
+ int uncompressed_digits;
+ int file_bits; /* window bits from the file */
+ int ok_bits; /* Set <16 on a successful read */
+ int cksum; /* Set on a checksum error */
+
+ /* PROTECTED ZLIB INFORMATION: USED BY THE ZLIB ROUTINES */
+ z_stream z;
+ png_uint_32 extra_bytes; /* Count of extra compressed bytes */
+ int state;
+ int rc; /* Last return code */
+ int window_bits; /* 0 if no change */
+ png_byte header[2];
+};
+
+static const char *
+zlib_flevel(struct zlib *zlib)
+{
+ switch (zlib->header[1] >> 6)
+ {
+ case 0: return "supfast";
+ case 1: return "stdfast";
+ case 2: return "default";
+ case 3: return "maximum";
+ default: assert(UNREACHED);
+ }
+
+ return "COMPILER BUG";
+}
+
+static const char *
+zlib_rc(struct zlib *zlib)
+ /* Return a string for the zlib return code */
+{
+ switch (zlib->rc)
+ {
+ case Z_OK: return "Z_OK";
+ case Z_STREAM_END: return "Z_STREAM_END";
+ case Z_NEED_DICT: return "Z_NEED_DICT";
+ case Z_ERRNO: return "Z_ERRNO";
+ case Z_STREAM_ERROR: return "Z_STREAM_ERROR";
+ case Z_DATA_ERROR: return "Z_DATA_ERROR";
+ case Z_MEM_ERROR: return "Z_MEM_ERROR";
+ case Z_BUF_ERROR: return "Z_BUF_ERROR";
+ case Z_VERSION_ERROR: return "Z_VERSION_ERROR";
+ default: return "Z_*INVALID_RC*";
+ }
+}
+
+static void
+zlib_message(struct zlib *zlib, int unexpected)
+ /* Output a message given a zlib rc */
+{
+ if (zlib->global->errors)
+ {
+ const char *reason = zlib->z.msg;
+
+ if (reason == NULL)
+ reason = "[no message]";
+
+ fputs(zlib->file->file_name, stderr);
+ type_sep(stderr);
+ type_name(zlib->chunk->chunk_type, stderr);
+ fprintf(stderr, ": %szlib error: %d (%s) (%s)\n",
+ unexpected ? "unexpected " : "", zlib->rc, zlib_rc(zlib), reason);
+ }
+}
+
+static void
+zlib_end(struct zlib *zlib)
+{
+ /* Output the summary line now; this ensures a summary line always gets
+ * output regardless of the manner of exit.
+ */
+ if (!zlib->global->quiet)
+ {
+ if (zlib->ok_bits < 16) /* stream was read ok */
+ {
+ const char *reason;
+
+ if (zlib->cksum)
+ reason = "CHK"; /* checksum error */
+
+ else if (zlib->ok_bits > zlib->file_bits)
+ reason = "TFB"; /* fixing a too-far-back error */
+
+ else if (zlib->ok_bits == zlib->file_bits)
+ reason = "OK ";
+
+ else
+ reason = "OPT"; /* optimizing window bits */
+
+ /* SUMMARY FORMAT (for a successful zlib inflate):
+ *
+ * IDAT reason flevel file-bits ok-bits compressed uncompressed file
+ */
+ type_name(zlib->chunk->chunk_type, stdout);
+ printf(" %s %s %d %d ", reason, zlib_flevel(zlib), zlib->file_bits,
+ zlib->ok_bits);
+ uarb_print(zlib->compressed_bytes, zlib->compressed_digits, stdout);
+ putc(' ', stdout);
+ uarb_print(zlib->uncompressed_bytes, zlib->uncompressed_digits,
+ stdout);
+ putc(' ', stdout);
+ fputs(zlib->file->file_name, stdout);
+ putc('\n', stdout);
+ }
+
+ else
+ {
+ /* This is a zlib read error; the chunk will be skipped. For an IDAT
+ * stream this will also cause a fatal read error (via stop()).
+ *
+ * SUMMARY FORMAT:
+ *
+ * IDAT SKP flevel file-bits z-rc compressed message file
+ *
+ * z-rc is the zlib failure code; message is the error message with
+ * spaces replaced by '-'. The compressed byte count indicates where
+ * in the zlib stream the error occurred.
+ */
+ type_name(zlib->chunk->chunk_type, stdout);
+ printf(" SKP %s %d %s ", zlib_flevel(zlib), zlib->file_bits,
+ zlib_rc(zlib));
+ uarb_print(zlib->compressed_bytes, zlib->compressed_digits, stdout);
+ putc(' ', stdout);
+ emit_string(zlib->z.msg ? zlib->z.msg : "[no_message]", stdout);
+ putc(' ', stdout);
+ fputs(zlib->file->file_name, stdout);
+ putc('\n', stdout);
+ }
+ }
+
+ if (zlib->state >= 0)
+ {
+ zlib->rc = inflateEnd(&zlib->z);
+
+ if (zlib->rc != Z_OK)
+ zlib_message(zlib, 1/*unexpected*/);
+ }
+
+ CLEAR(*zlib);
+}
+
+static int
+zlib_reset(struct zlib *zlib, int window_bits)
+ /* Reinitializes a zlib with a different window_bits */
+{
+ assert(zlib->state >= 0); /* initialized by zlib_init */
+
+ zlib->z.next_in = Z_NULL;
+ zlib->z.avail_in = 0;
+ zlib->z.next_out = Z_NULL;
+ zlib->z.avail_out = 0;
+
+ zlib->window_bits = window_bits;
+ zlib->compressed_digits = 0;
+ zlib->uncompressed_digits = 0;
+
+ zlib->state = 0; /* initialized, once */
+ zlib->rc = inflateReset2(&zlib->z, 0);
+ if (zlib->rc != Z_OK)
+ {
+ zlib_message(zlib, 1/*unexpected*/);
+ return 0;
+ }
+
+ return 1;
+}
+
+static int
+zlib_init(struct zlib *zlib, struct IDAT *idat, struct chunk *chunk,
+ int window_bits, png_uint_32 offset)
+ /* Initialize a zlib_control; the result is true/false */
+{
+ CLEAR(*zlib);
+
+ zlib->idat = idat;
+ zlib->chunk = chunk;
+ zlib->file = chunk->file;
+ zlib->global = chunk->global;
+ zlib->rewrite_offset = offset; /* never changed for this zlib */
+
+ /* *_out does not need to be set: */
+ zlib->z.next_in = Z_NULL;
+ zlib->z.avail_in = 0;
+ zlib->z.zalloc = Z_NULL;
+ zlib->z.zfree = Z_NULL;
+ zlib->z.opaque = Z_NULL;
+
+ zlib->state = -1;
+ zlib->window_bits = window_bits;
+
+ zlib->compressed_digits = 0;
+ zlib->uncompressed_digits = 0;
+
+ /* These values are sticky across reset (in addition to the stuff in the
+ * first block, which is actually constant.)
+ */
+ zlib->file_bits = 24;
+ zlib->ok_bits = 16; /* unset */
+ zlib->cksum = 0; /* set when a checksum error is detected */
+
+ /* '0' means use the header; inflateInit2 should always succeed because it
+ * does nothing apart from allocating the internal zstate.
+ */
+ zlib->rc = inflateInit2(&zlib->z, 0);
+ if (zlib->rc != Z_OK)
+ {
+ zlib_message(zlib, 1/*unexpected*/);
+ return 0;
+ }
+
+ else
+ {
+ zlib->state = 0; /* initialized */
+ return 1;
+ }
+}
+
+static int
+max_window_bits(uarbc size, int ndigits)
+ /* Return the zlib stream window bits required for data of the given size. */
+{
+ png_uint_16 cb;
+
+ if (ndigits > 1)
+ return 15;
+
+ cb = size[0];
+
+ if (cb > 16384) return 15;
+ if (cb > 8192) return 14;
+ if (cb > 4096) return 13;
+ if (cb > 2048) return 12;
+ if (cb > 1024) return 11;
+ if (cb > 512) return 10;
+ if (cb > 256) return 9;
+ return 8;
+}
+
+static int
+zlib_advance(struct zlib *zlib, png_uint_32 nbytes)
+ /* Read nbytes compressed bytes; the stream will be initialized if required.
+ * Bytes are always being reread and errors are fatal. The return code is as
+ * follows:
+ *
+ * -1: saw the "too far back" error
+ * 0: ok, keep going
+ * 1: saw Z_STREAM_END (zlib->extra_bytes indicates too much data)
+ * 2: a zlib error that cannot be corrected (error message already
+ * output if required.)
+ */
+# define ZLIB_TOO_FAR_BACK (-1)
+# define ZLIB_OK 0
+# define ZLIB_STREAM_END 1
+# define ZLIB_FATAL 2
+{
+ int state = zlib->state;
+ int endrc = ZLIB_OK;
+ png_uint_32 in_bytes = 0;
+ struct file *file = zlib->file;
+
+ assert(state >= 0);
+
+ while (in_bytes < nbytes && endrc == ZLIB_OK)
+ {
+ png_uint_32 out_bytes;
+ int flush;
+ png_byte bIn = reread_byte(file);
+ png_byte bOut;
+
+ switch (state)
+ {
+ case 0: /* first header byte */
+ {
+ int file_bits = 8+(bIn >> 4);
+ int new_bits = zlib->window_bits;
+
+ zlib->file_bits = file_bits;
+
+ /* Check against the existing value - it may not need to be
+ * changed. Note that a bogus file_bits is allowed through once,
+ * to see if it works, but the window_bits value is set to 15,
+ * the maximum.
+ */
+ if (new_bits == 0) /* no change */
+ zlib->window_bits = ((file_bits > 15) ? 15 : file_bits);
+
+ else if (new_bits != file_bits) /* rewrite required */
+ bIn = (png_byte)((bIn & 0xf) + ((new_bits-8) << 4));
+ }
+
+ zlib->header[0] = bIn;
+ zlib->state = state = 1;
+ break;
+
+ case 1: /* second header byte */
+ {
+ int b2 = bIn & 0xe0; /* top 3 bits */
+
+ /* The checksum calculation, on the first 11 bits: */
+ b2 += 0x1f - ((zlib->header[0] << 8) + b2) % 0x1f;
+
+ /* Update the checksum byte if required: */
+ if (bIn != b2)
+ {
+ /* If the first byte wasn't changed this indicates an error in
+ * the checksum calculation; signal this by setting 'cksum'.
+ */
+ if (zlib->file_bits == zlib->window_bits)
+ zlib->cksum = 1;
+
+ bIn = (png_byte)b2;
+ }
+ }
+
+ zlib->header[1] = bIn;
+ zlib->state = state = 2;
+ break;
+
+ default: /* After the header bytes */
+ break;
+ }
+
+ /* For some streams, perhaps only those compressed with 'superfast
+ * compression' (which results in a lot of copying) Z_BUF_ERROR can happen
+ * immediately after all output has been flushed on the next input byte.
+ * This is handled below when Z_BUF_ERROR is detected by adding an output
+ * byte.
+ */
+ zlib->z.next_in = &bIn;
+ zlib->z.avail_in = 1;
+ zlib->z.next_out = &bOut;
+ zlib->z.avail_out = 0; /* Initially */
+
+ /* Initially use Z_NO_FLUSH in an attempt to persuade zlib to look at this
+ * byte without confusing what is going on with output.
+ */
+ flush = Z_NO_FLUSH;
+ out_bytes = 0;
+
+ /* NOTE: expression 3 is only evaluted on 'continue', because of the
+ * 'break' at the end of this loop below.
+ */
+ for (;endrc == ZLIB_OK;
+ flush = Z_SYNC_FLUSH,
+ zlib->z.next_out = &bOut,
+ zlib->z.avail_out = 1,
+ ++out_bytes)
+ {
+ zlib->rc = inflate(&zlib->z, flush);
+ out_bytes -= zlib->z.avail_out;
+
+ switch (zlib->rc)
+ {
+ case Z_BUF_ERROR:
+ if (zlib->z.avail_out == 0)
+ continue; /* Try another output byte. */
+
+ if (zlib->z.avail_in == 0)
+ break; /* Try another input byte */
+
+ /* Both avail_out and avail_in are 1 yet zlib returned a code
+ * indicating no progress was possible. This is unexpected.
+ */
+ zlib_message(zlib, 1/*unexpected*/);
+ endrc = ZLIB_FATAL; /* stop processing */
+ break;
+
+ case Z_OK:
+ /* Zlib is supposed to have made progress: */
+ assert(zlib->z.avail_out == 0 || zlib->z.avail_in == 0);
+ continue;
+
+ case Z_STREAM_END:
+ /* This is the successful end. */
+ zlib->state = 3; /* end of stream */
+ endrc = ZLIB_STREAM_END;
+ break;
+
+ case Z_NEED_DICT:
+ zlib_message(zlib, 0/*stream error*/);
+ endrc = ZLIB_FATAL;
+ break;
+
+ case Z_DATA_ERROR:
+ /* The too far back error can be corrected, others cannot: */
+ if (zlib->z.msg != NULL &&
+ strcmp(zlib->z.msg, "invalid distance too far back") == 0)
+ {
+ endrc = ZLIB_TOO_FAR_BACK;
+ break;
+ }
+ /* FALL THROUGH */
+
+ default:
+ zlib_message(zlib, 0/*stream error*/);
+ endrc = ZLIB_FATAL;
+ break;
+ } /* switch (inflate rc) */
+
+ /* Control gets here when further output is not possible; endrc may
+ * still be ZLIB_OK if more input is required.
+ */
+ break;
+ } /* for (output bytes) */
+
+ /* Keep a running count of output byte produced: */
+ zlib->uncompressed_digits = uarb_add32(zlib->uncompressed_bytes,
+ zlib->uncompressed_digits, out_bytes);
+
+ /* Keep going, the loop will terminate when endrc is no longer set to
+ * ZLIB_OK or all the input bytes have been consumed; meanwhile keep
+ * adding input bytes.
+ */
+ assert(zlib->z.avail_in == 0 || endrc != ZLIB_OK);
+
+ in_bytes += 1 - zlib->z.avail_in;
+ } /* while (input bytes) */
+
+ assert(in_bytes == nbytes || endrc != ZLIB_OK);
+
+ /* Update the running total of input bytes consumed */
+ zlib->compressed_digits = uarb_add32(zlib->compressed_bytes,
+ zlib->compressed_digits, in_bytes - zlib->z.avail_in);
+
+ /* At the end of the stream update the chunk with the accumulated
+ * information if it is an improvement:
+ */
+ if (endrc == ZLIB_STREAM_END && zlib->window_bits < zlib->ok_bits)
+ {
+ struct chunk *chunk = zlib->chunk;
+
+ chunk->uncompressed_digits = uarb_copy(chunk->uncompressed_bytes,
+ zlib->uncompressed_bytes, zlib->uncompressed_digits);
+ chunk->compressed_digits = uarb_copy(chunk->compressed_bytes,
+ zlib->compressed_bytes, zlib->compressed_digits);
+ chunk->rewrite_buffer[0] = zlib->header[0];
+ chunk->rewrite_buffer[1] = zlib->header[1];
+
+ if (zlib->window_bits != zlib->file_bits || zlib->cksum)
+ {
+ /* A rewrite is required */
+ chunk->rewrite_offset = zlib->rewrite_offset;
+ chunk->rewrite_length = 2;
+ }
+
+ else
+ {
+ chunk->rewrite_offset = 0;
+ chunk->rewrite_length = 0;
+ }
+
+ if (in_bytes < nbytes)
+ chunk_message(chunk, "extra compressed data");
+
+ zlib->extra_bytes = nbytes - in_bytes;
+ zlib->ok_bits = zlib->window_bits;
+ }
+
+ return endrc;
+}
+
+static int
+zlib_run(struct zlib *zlib)
+ /* Like zlib_advance but also handles a stream of IDAT chunks. */
+{
+ /* The 'extra_bytes' field is set by zlib_advance if there is extra
+ * compressed data in the chunk it handles (if it sees Z_STREAM_END before
+ * all the input data has been used.) This function uses the value to update
+ * the correct chunk length, so the problem should only ever be detected once
+ * for each chunk. zlib_advance outputs the error message, though see the
+ * IDAT specific check below.
+ */
+ zlib->extra_bytes = 0;
+
+ if (zlib->idat != NULL)
+ {
+ struct IDAT_list *list = zlib->idat->idat_list_head;
+ struct IDAT_list *last = zlib->idat->idat_list_tail;
+ int skip = 0;
+
+ /* 'rewrite_offset' is the offset of the LZ data within the chunk, for
+ * IDAT it should be 0:
+ */
+ assert(zlib->rewrite_offset == 0);
+
+ /* Process each IDAT_list in turn; the caller has left the stream
+ * positioned at the start of the first IDAT chunk data.
+ */
+ for (;;)
+ {
+ const unsigned int count = list->count;
+ unsigned int i;
+
+ for (i = 0; i<count; ++i)
+ {
+ int rc;
+
+ if (skip > 0) /* Skip CRC and next IDAT header */
+ skip_12(zlib->file);
+
+ skip = 12; /* for the next time */
+
+ rc = zlib_advance(zlib, list->lengths[i]);
+
+ switch (rc)
+ {
+ case ZLIB_OK: /* keep going */
+ break;
+
+ case ZLIB_STREAM_END: /* stop */
+ /* There may be extra chunks; if there are and one of them is
+ * not zero length output the 'extra data' message. Only do
+ * this check if errors are being output.
+ */
+ if (zlib->global->errors && zlib->extra_bytes == 0)
+ {
+ struct IDAT_list *check = list;
+ int j = i+1, jcount = count;
+
+ for (;;)
+ {
+ for (; j<jcount; ++j)
+ if (check->lengths[j] > 0)
+ {
+ chunk_message(zlib->chunk,
+ "extra compressed data");
+ goto end_check;
+ }
+
+ if (check == last)
+ break;
+
+ check = check->next;
+ jcount = check->count;
+ j = 0;
+ }
+ }
+
+ end_check:
+ /* Terminate the list at the current position, reducing the
+ * length of the last IDAT too if required.
+ */
+ list->lengths[i] -= zlib->extra_bytes;
+ list->count = i+1;
+ zlib->idat->idat_list_tail = list;
+ /* FALL THROUGH */
+
+ default:
+ return rc;
+ }
+ }
+
+ /* At the end of the compressed data and Z_STREAM_END was not seen. */
+ if (list == last)
+ return ZLIB_OK;
+
+ list = list->next;
+ }
+ }
+
+ else
+ {
+ struct chunk *chunk = zlib->chunk;
+ int rc;
+
+ assert(zlib->rewrite_offset < chunk->chunk_length);
+
+ rc = zlib_advance(zlib, chunk->chunk_length - zlib->rewrite_offset);
+
+ /* The extra bytes in the chunk are handled now by adjusting the chunk
+ * length to exclude them; the zlib data is always stored at the end of
+ * the PNG chunk (although clearly this is not necessary.) zlib_advance
+ * has already output a warning message.
+ */
+ chunk->chunk_length -= zlib->extra_bytes;
+ return rc;
+ }
+}
+
+static int /* global function; not a member function */
+zlib_check(struct file *file, png_uint_32 offset)
+ /* Check the stream of zlib compressed data in either idat (if given) or (if
+ * not) chunk. In fact it is zlib_run that handles the difference in reading
+ * a single chunk and a list of IDAT chunks.
+ *
+ * In either case the input file must be positioned at the first byte of zlib
+ * compressed data (the first header byte).
+ *
+ * The return value is true on success, including the case where the zlib
+ * header may need to be rewritten, and false on an unrecoverable error.
+ *
+ * In the case of IDAT chunks 'offset' should be 0.
+ */
+{
+ fpos_t start_pos;
+ struct zlib zlib;
+
+ /* Record the start of the LZ data to allow a re-read. */
+ file_getpos(file, &start_pos);
+
+ /* First test the existing (file) window bits: */
+ if (zlib_init(&zlib, file->idat, file->chunk, 0/*window bits*/, offset))
+ {
+ int min_bits, max_bits, rc;
+
+ /* The first run using the existing window bits. */
+ rc = zlib_run(&zlib);
+
+ switch (rc)
+ {
+ case ZLIB_TOO_FAR_BACK:
+ /* too far back error */
+ file->status_code |= TOO_FAR_BACK;
+ min_bits = zlib.window_bits + 1;
+ max_bits = 15;
+ break;
+
+ case ZLIB_STREAM_END:
+ if (!zlib.global->optimize_zlib &&
+ zlib.window_bits == zlib.file_bits && !zlib.cksum)
+ {
+ /* The trivial case where the stream is ok and optimization was
+ * not requested.
+ */
+ zlib_end(&zlib);
+ return 1;
+ }
+
+ max_bits = max_window_bits(zlib.uncompressed_bytes,
+ zlib.uncompressed_digits);
+ if (zlib.ok_bits < max_bits)
+ max_bits = zlib.ok_bits;
+ min_bits = 8;
+
+ /* cksum is set if there is an error in the zlib header checksum
+ * calculation in the original file (and this may be the only reason
+ * a rewrite is required). We can't rely on the file window bits in
+ * this case, so do the optimization anyway.
+ */
+ if (zlib.cksum)
+ chunk_message(zlib.chunk, "zlib checkum");
+ break;
+
+
+ case ZLIB_OK:
+ /* Truncated stream; unrecoverable, gets converted to ZLIB_FATAL */
+ zlib.z.msg = PNGZ_MSG_CAST("[truncated]");
+ zlib_message(&zlib, 0/*expected*/);
+ /* FALL THROUGH */
+
+ default:
+ /* Unrecoverable error; skip the chunk; a zlib_message has already
+ * been output.
+ */
+ zlib_end(&zlib);
+ return 0;
+ }
+
+ /* Optimize window bits or fix a too-far-back error. min_bits and
+ * max_bits have been set appropriately, ok_bits records the bit value
+ * known to work.
+ */
+ while (min_bits < max_bits || max_bits < zlib.ok_bits/*if 16*/)
+ {
+ int test_bits = (min_bits + max_bits) >> 1;
+
+ if (zlib_reset(&zlib, test_bits))
+ {
+ file_setpos(file, &start_pos);
+ rc = zlib_run(&zlib);
+
+ switch (rc)
+ {
+ case ZLIB_TOO_FAR_BACK:
+ min_bits = test_bits+1;
+ if (min_bits > max_bits)
+ {
+ /* This happens when the stream really is damaged and it
+ * contains a distance code that addresses bytes before
+ * the start of the uncompressed data.
+ */
+ assert(test_bits == 15);
+
+ /* Output the error that wasn't output before: */
+ if (zlib.z.msg == NULL)
+ zlib.z.msg = PNGZ_MSG_CAST(
+ "invalid distance too far back");
+ zlib_message(&zlib, 0/*stream error*/);
+ zlib_end(&zlib);
+ return 0;
+ }
+ break;
+
+ case ZLIB_STREAM_END: /* success */
+ max_bits = test_bits;
+ break;
+
+ default:
+ /* A fatal error; this happens if a too-far-back error was
+ * hiding a more serious error, zlib_advance has already
+ * output a zlib_message.
+ */
+ zlib_end(&zlib);
+ return 0;
+ }
+ }
+
+ else /* inflateReset2 failed */
+ {
+ zlib_end(&zlib);
+ return 0;
+ }
+ }
+
+ /* The loop guarantees this */
+ assert(zlib.ok_bits == max_bits);
+ zlib_end(&zlib);
+ return 1;
+ }
+
+ else /* zlib initialization failed - skip the chunk */
+ {
+ zlib_end(&zlib);
+ return 0;
+ }
+}
+
+/***************************** LIBPNG CALLBACKS *******************************/
+/* The strategy here is to run a regular libpng PNG file read but examine the
+ * input data (from the file) before passing it to libpng so as to be aware of
+ * the state we expect libpng to be in. Warning and error callbacks are also
+ * intercepted so that they can be quieted and interpreted. Interpretation
+ * depends on a somewhat risky string match for known error messages; let us
+ * hope that this can be fixed in the next version of libpng.
+ *
+ * The control structure is pointed to by the libpng error pointer. It contains
+ * that set of structures which must persist across multiple read callbacks,
+ * which is pretty much everything except the 'zlib' control structure.
+ *
+ * The file structure is instantiated in the caller of the per-file routine, but
+ * the per-file routine contains the chunk and IDAT control structures.
+ */
+/* The three routines read_chunk, process_chunk and sync_stream can only be
+ * called via a call to read_chunk and only exit at a return from process_chunk.
+ * These routines could have been written as one confusing large routine,
+ * instead this code relies on the compiler to do tail call elimination. The
+ * possible calls are as follows:
+ *
+ * read_chunk
+ * -> sync_stream
+ * -> process_chunk
+ * -> process_chunk
+ * -> read_chunk
+ * returns
+ */
+static void read_chunk(struct file *file);
+static void
+process_chunk(struct file *file, png_uint_32 file_crc, png_uint_32 next_length,
+ png_uint_32 next_type)
+ /* Called when the chunk data has been read, next_length and next_type
+ * will be set for the next chunk (or 0 if this is IEND).
+ *
+ * When this routine returns, chunk_length and chunk_type will be set for the
+ * next chunk to write because if a chunk is skipped this return calls back
+ * to read_chunk.
+ */
+{
+ const png_uint_32 type = file->type;
+
+ if (file->global->verbose > 1)
+ {
+ fputs(" ", stderr);
+ type_name(file->type, stderr);
+ fprintf(stderr, " %lu 0x%.8x 0x%.8x\n", (unsigned long)file->length,
+ file->crc ^ 0xffffffff, file_crc);
+ }
+
+ /* The basic structure seems correct but the CRC may not match, in this
+ * case assume that it is simply a bad CRC, either wrongly calculated or
+ * because of damaged stream data.
+ */
+ if ((file->crc ^ 0xffffffff) != file_crc)
+ {
+ /* The behavior is set by the 'skip' setting; if it is anything other
+ * than SKIP_BAD_CRC ignore the bad CRC and return the chunk, with a
+ * corrected CRC and possibly processed, to libpng. Otherwise skip the
+ * chunk, which will result in a fatal error if the chunk is critical.
+ */
+ file->status_code |= CRC_ERROR;
+
+ /* Ignore the bad CRC */
+ if (file->global->skip != SKIP_BAD_CRC)
+ type_message(file, type, "bad CRC");
+
+ /* This will cause an IEND with a bad CRC to stop */
+ else if (CRITICAL(type))
+ stop(file, READ_ERROR_CODE, "bad CRC in critical chunk");
+
+ else
+ {
+ type_message(file, type, "skipped: bad CRC");
+
+ /* NOTE: this cannot be reached for IEND because it is critical. */
+ goto skip_chunk;
+ }
+ }
+
+ /* Check for other 'skip' cases and handle these; these only apply to
+ * ancillary chunks (and not tRNS, which should probably have been a critical
+ * chunk.)
+ */
+ if (skip_chunk_type(file->global, type))
+ goto skip_chunk;
+
+ /* The chunk may still be skipped if problems are detected in the LZ data,
+ * however the LZ data check requires a chunk. Handle this by instantiating
+ * a chunk unless an IDAT is already instantiated (IDAT control structures
+ * instantiate their own chunk.)
+ */
+ if (type != png_IDAT)
+ file->alloc(file, 0/*chunk*/);
+
+ else if (file->idat == NULL)
+ file->alloc(file, 1/*IDAT*/);
+
+ else
+ {
+ /* The chunk length must be updated for process_IDAT */
+ assert(file->chunk != NULL);
+ assert(file->chunk->chunk_type == png_IDAT);
+ file->chunk->chunk_length = file->length;
+ }
+
+ /* Record the 'next' information too, now that the original values for
+ * this chunk have been copied. Notice that the IDAT chunks only make a
+ * copy of the position of the first chunk, this is fine - process_IDAT does
+ * not need the position of this chunk.
+ */
+ file->length = next_length;
+ file->type = next_type;
+ getpos(file);
+
+ /* Do per-type processing, note that if this code does not return from the
+ * function the chunk will be skipped. The rewrite is cancelled here so that
+ * it can be set in the per-chunk processing.
+ */
+ file->chunk->rewrite_length = 0;
+ file->chunk->rewrite_offset = 0;
+ switch (type)
+ {
+ default:
+ return;
+
+ case png_IHDR:
+ /* Read this now and update the control structure with the information
+ * it contains. The header is validated completely to ensure this is a
+ * PNG.
+ */
+ {
+ struct chunk *chunk = file->chunk;
+
+ if (chunk->chunk_length != 13)
+ stop_invalid(file, "IHDR length");
+
+ /* Read all the IHDR information and validate it. */
+ setpos(chunk);
+ file->width = reread_4(file);
+ file->height = reread_4(file);
+ file->bit_depth = reread_byte(file);
+ file->color_type = reread_byte(file);
+ file->compression_method = reread_byte(file);
+ file->filter_method = reread_byte(file);
+ file->interlace_method = reread_byte(file);
+
+ /* This validates all the fields, and calls stop_invalid if
+ * there is a problem.
+ */
+ calc_image_size(file);
+ }
+ return;
+
+ /* Ancillary chunks that require further processing: */
+ case png_zTXt: case png_iCCP:
+ if (process_zTXt_iCCP(file))
+ return;
+ chunk_end(&file->chunk);
+ file_setpos(file, &file->data_pos);
+ break;
+
+ case png_iTXt:
+ if (process_iTXt(file))
+ return;
+ chunk_end(&file->chunk);
+ file_setpos(file, &file->data_pos);
+ break;
+
+ case png_IDAT:
+ if (process_IDAT(file))
+ return;
+ /* First pass: */
+ assert(next_type == png_IDAT);
+ break;
+ }
+
+ /* Control reaches this point if the chunk must be skipped. For chunks other
+ * than IDAT this means that the zlib compressed data is fatally damanged and
+ * the chunk will not be passed to libpng. For IDAT it means that the end of
+ * the IDAT stream has not yet been reached and we must handle the next
+ * (IDAT) chunk. If the LZ data in an IDAT stream cannot be read 'stop' must
+ * be used to halt parsing of the PNG.
+ */
+ read_chunk(file);
+ return;
+
+ /* This is the generic code to skip the current chunk; simply jump to the
+ * next one.
+ */
+skip_chunk:
+ file->length = next_length;
+ file->type = next_type;
+ getpos(file);
+ read_chunk(file);
+}
+
+static png_uint_32
+get32(png_bytep buffer, int offset)
+ /* Read a 32-bit value from an 8-byte circular buffer (used only below).
+ */
+{
+ return
+ (buffer[ offset & 7] << 24) +
+ (buffer[(offset+1) & 7] << 16) +
+ (buffer[(offset+2) & 7] << 8) +
+ (buffer[(offset+3) & 7] );
+}
+
+static void
+sync_stream(struct file *file)
+ /* The stream seems to be messed up, attempt to resync from the current chunk
+ * header. Executes stop on a fatal error, otherwise calls process_chunk.
+ */
+{
+ png_uint_32 file_crc;
+
+ file->status_code |= STREAM_ERROR;
+
+ if (file->global->verbose)
+ {
+ fputs(" SYNC ", stderr);
+ type_name(file->type, stderr);
+ putc('\n', stderr);
+ }
+
+ /* Return to the start of the chunk data */
+ file_setpos(file, &file->data_pos);
+ file->read_count = 8;
+
+ if (read_4(file, &file_crc) == 4) /* else completely truncated */
+ {
+ /* Ignore the recorded chunk length, proceed through the data looking for
+ * a leading sequence of bytes that match the CRC in the following four
+ * bytes. Each time a match is found check the next 8 bytes for a valid
+ * length, chunk-type pair.
+ */
+ png_uint_32 length;
+ png_uint_32 type = file->type;
+ png_uint_32 crc = crc_init_4(type);
+ png_byte buffer[8];
+ unsigned int nread = 0, nused = 0;
+
+ for (length=0; length <= 0x7fffffff; ++length)
+ {
+ int ch;
+
+ if ((crc ^ 0xffffffff) == file_crc)
+ {
+ /* A match on the CRC; for IEND this is sufficient, but for anything
+ * else expect a following chunk header.
+ */
+ if (type == png_IEND)
+ {
+ file->length = length;
+ process_chunk(file, file_crc, 0, 0);
+ return;
+ }
+
+ else
+ {
+ /* Need 8 bytes */
+ while (nread < 8+nused)
+ {
+ ch = read_byte(file);
+ if (ch == EOF)
+ goto truncated;
+ buffer[(nread++) & 7] = (png_byte)ch;
+ }
+
+ /* Prevent overflow */
+ nread -= nused & ~7;
+ nused -= nused & ~7; /* or, nused &= 7 ;-) */
+
+ /* Examine the 8 bytes for a valid chunk header. */
+ {
+ png_uint_32 next_length = get32(buffer, nused);
+
+ if (next_length < 0x7fffffff)
+ {
+ png_uint_32 next_type = get32(buffer, nused+4);
+
+ if (chunk_type_valid(next_type))
+ {
+ file->read_count -= 8;
+ process_chunk(file, file_crc, next_length, next_type);
+ return;
+ }
+ }
+
+ /* Not valid, keep going. */
+ }
+ }
+ }
+
+ /* This catches up with the circular buffer which gets filled above
+ * while checking a chunk header. This code is slightly tricky - if
+ * the chunk_type is IEND the buffer will never be used, if it is not
+ * the code will always read ahead exactly 8 bytes and pass this on to
+ * process_chunk. So the invariant that IEND leaves the file position
+ * after the IEND CRC and other chunk leave it after the *next* chunk
+ * header is not broken.
+ */
+ if (nread <= nused)
+ {
+ ch = read_byte(file);
+
+ if (ch == EOF)
+ goto truncated;
+ }
+
+ else
+ ch = buffer[(++nused) & 7];
+
+ crc = crc_one_byte(crc, file_crc >> 24);
+ file_crc = (file_crc << 8) + ch;
+ }
+
+ /* Control gets to here if when 0x7fffffff bytes (plus 8) have been read,
+ * ok, treat this as a damaged stream too:
+ */
+ }
+
+truncated:
+ stop(file, READ_ERROR_CODE, "damaged PNG stream");
+}
+
+static void
+read_chunk(struct file *file)
+ /* On entry file::data_pos must be set to the position of the first byte
+ * of the chunk data *and* the input file must be at this position. This
+ * routine (via process_chunk) instantiates a chunk or IDAT control structure
+ * based on file::length and file::type and also resets these fields and
+ * file::data_pos for the chunk after this one. For an IDAT chunk the whole
+ * stream of IDATs will be read, until something other than an IDAT is
+ * encountered, and the file fields will be set for the chunk after the end
+ * of the stream of IDATs.
+ *
+ * For IEND the file::type field will be set to 0, and nothing beyond the end
+ * of the IEND chunk will have been read.
+ */
+{
+ png_uint_32 length = file->length;
+ png_uint_32 type = file->type;
+
+ /* After IEND file::type is set to 0, if libpng attempts to read
+ * more data at this point this is a bug in libpng.
+ */
+ if (type == 0)
+ stop(file, UNEXPECTED_ERROR_CODE, "read beyond IEND");
+
+ if (file->global->verbose > 2)
+ {
+ fputs(" ", stderr);
+ type_name(type, stderr);
+ fprintf(stderr, " %lu\n", (unsigned long)length);
+ }
+
+ /* Start the read_crc calculation with the chunk type, then read to the end
+ * of the chunk data (without processing it in any way) to check that it is
+ * all there and calculate the CRC.
+ */
+ file->crc = crc_init_4(type);
+ if (crc_read_many(file, length)) /* else it was truncated */
+ {
+ png_uint_32 file_crc; /* CRC read from file */
+ unsigned int nread = read_4(file, &file_crc);
+
+ if (nread == 4)
+ {
+ if (type != png_IEND) /* do not read beyond IEND */
+ {
+ png_uint_32 next_length;
+
+ nread += read_4(file, &next_length);
+ if (nread == 8 && next_length <= 0x7fffffff)
+ {
+ png_uint_32 next_type;
+
+ nread += read_4(file, &next_type);
+
+ if (nread == 12 && chunk_type_valid(next_type))
+ {
+ /* Adjust the read count back to the correct value for this
+ * chunk.
+ */
+ file->read_count -= 8;
+ process_chunk(file, file_crc, next_length, next_type);
+ return;
+ }
+ }
+ }
+
+ else /* IEND */
+ {
+ process_chunk(file, file_crc, 0, 0);
+ return;
+ }
+ }
+ }
+
+ /* Control gets to here if the the stream seems invalid or damaged in some
+ * way. Either there was a problem reading all the expected data (this
+ * chunk's data, its CRC and the length and type of the next chunk) or the
+ * next chunk length/type are invalid. Notice that the cases that end up
+ * here all correspond to cases that would otherwise terminate the read of
+ * the PNG file.
+ */
+ sync_stream(file);
+}
+
+/* This returns a file* from a png_struct in an implementation specific way. */
+static struct file *get_control(png_const_structrp png_ptr);
+
+static void PNGCBAPI
+error_handler(png_structp png_ptr, png_const_charp message)
+{
+ stop(get_control(png_ptr), LIBPNG_ERROR_CODE, message);
+}
+
+static void PNGCBAPI
+warning_handler(png_structp png_ptr, png_const_charp message)
+{
+ struct file *file = get_control(png_ptr);
+
+ if (file->global->warnings)
+ emit_error(file, LIBPNG_WARNING_CODE, message);
+}
+
+/* Read callback - this is where the work gets done to check the stream before
+ * passing it to libpng
+ */
+static void PNGCBAPI
+read_callback(png_structp png_ptr, png_bytep buffer, size_t count)
+ /* Return 'count' bytes to libpng in 'buffer' */
+{
+ struct file *file = get_control(png_ptr);
+ png_uint_32 type, length; /* For the chunk be *WRITTEN* */
+ struct chunk *chunk;
+
+ /* libpng should always ask for at least one byte */
+ if (count == 0)
+ stop(file, UNEXPECTED_ERROR_CODE, "read callback for 0 bytes");
+
+ /* The callback always reads ahead by 8 bytes - the signature or chunk header
+ * - these bytes are stored in chunk_length and chunk_type. This block is
+ * executed once for the signature and once for the first chunk right at the
+ * start.
+ */
+ if (file->read_count < 8)
+ {
+ assert(file->read_count == 0);
+ assert((file->status_code & TRUNCATED) == 0);
+
+ (void)read_4(file, &file->length);
+
+ if (file->read_count == 4)
+ (void)read_4(file, &file->type);
+
+ if (file->read_count < 8)
+ {
+ assert((file->status_code & TRUNCATED) != 0);
+ stop(file, READ_ERROR_CODE, "not a PNG (too short)");
+ }
+
+ if (file->state == STATE_SIGNATURE)
+ {
+ if (file->length != sig1 || file->type != sig2)
+ stop(file, LIBPNG_ERROR_CODE, "not a PNG (signature)");
+
+ /* Else write it (this is the initialization of write_count, prior to
+ * this it contains CLEAR garbage.)
+ */
+ file->write_count = 0;
+ }
+
+ else
+ {
+ assert(file->state == STATE_CHUNKS);
+
+ /* The first chunk must be a well formed IHDR (this could be relaxed to
+ * use the checks in process_chunk, but that seems unnecessary.)
+ */
+ if (file->length != 13 || file->type != png_IHDR)
+ stop(file, LIBPNG_ERROR_CODE, "not a PNG (IHDR)");
+
+ /* The position of the data must be stored too */
+ getpos(file);
+ }
+ }
+
+ /* Retrieve previous state (because the read callbacks are made pretty much
+ * byte-by-byte in the sequential reader prior to 1.7).
+ */
+ chunk = file->chunk;
+
+ if (chunk != NULL)
+ {
+ length = chunk->chunk_length;
+ type = chunk->chunk_type;
+ }
+
+ else
+ {
+ /* This is the signature case; for IDAT and other chunks these values will
+ * be overwritten when read_chunk is called below.
+ */
+ length = file->length;
+ type = file->type;
+ }
+
+ do
+ {
+ png_uint_32 b;
+
+ /* Complete the read of a chunk; as a side effect this also instantiates
+ * a chunk control structure and sets the file length/type/data_pos fields
+ * for the *NEXT* chunk header.
+ *
+ * NOTE: at an IDAT any following IDAT chunks will also be read and the
+ * next_ fields will refer to the chunk after the last IDAT.
+ *
+ * NOTE: read_chunk only returns when it has read a chunk that must now be
+ * written.
+ */
+ if (file->state != STATE_SIGNATURE && chunk == NULL)
+ {
+ assert(file->read_count == 8);
+ assert(file->idat == NULL);
+ read_chunk(file);
+ chunk = file->chunk;
+ assert(chunk != NULL);
+
+ /* Do the initialization that was not done before. */
+ length = chunk->chunk_length;
+ type = chunk->chunk_type;
+
+ /* And start writing the new chunk. */
+ file->write_count = 0;
+ }
+
+ /* The chunk_ fields describe a chunk that must be written, or hold the
+ * signature. Write the header first. In the signature case this
+ * rewrites the signature.
+ */
+ switch (file->write_count)
+ {
+ case 0: b = length >> 24; break;
+ case 1: b = length >> 16; break;
+ case 2: b = length >> 8; break;
+ case 3: b = length ; break;
+
+ case 4: b = type >> 24; break;
+ case 5: b = type >> 16; break;
+ case 6: b = type >> 8; break;
+ case 7: b = type ; break;
+
+ case 8:
+ /* The header has been written. If this is really the signature
+ * that's all that is required and we can go to normal chunk
+ * processing.
+ */
+ if (file->state == STATE_SIGNATURE)
+ {
+ /* The signature has been written, the tail call to read_callback
+ * below (it's just a goto to the start with a decent compiler)
+ * will read the IHDR header ahead and validate it.
+ */
+ assert(length == sig1 && type == sig2);
+ file->read_count = 0; /* Forces a header read */
+ file->state = STATE_CHUNKS; /* IHDR: checked above */
+ read_callback(png_ptr, buffer, count);
+ return;
+ }
+
+ else
+ {
+ assert(chunk != NULL);
+
+ /* Set up for write, notice that repositioning the input stream
+ * is only necessary if something is to be read from it. Also
+ * notice that for the IDAT stream this must only happen once -
+ * on the first IDAT - to get back to the start of the list and
+ * this is done inside process_IDAT:
+ */
+ chunk->write_crc = crc_init_4(type);
+ if (file->state != STATE_IDAT && length > 0)
+ setpos(chunk);
+ }
+ /* FALL THROUGH */
+
+ default:
+ assert(chunk != NULL);
+
+ /* NOTE: the arithmetic below overflows and gives a large positive
+ * png_uint_32 value until the whole chunk data has been written.
+ */
+ switch (file->write_count - length)
+ {
+ /* Write the chunk data, normally this just comes from
+ * the file. The only exception is for that part of a
+ * chunk which is zlib data and which must be rewritten,
+ * and IDAT chunks which can be completely
+ * reconstructed.
+ */
+ default:
+ if (file->state == STATE_IDAT)
+ {
+ struct IDAT *idat = file->idat;
+
+ assert(idat != NULL);
+
+ /* Read an IDAT byte from the input stream of IDAT chunks.
+ * Because the IDAT stream can be re-chunked this stream is
+ * held in the struct IDAT members. The chunk members, in
+ * particular chunk_length (and therefore the length local)
+ * refer to the output chunk.
+ */
+ while (idat->idat_index >= idat->idat_length)
+ {
+ /* Advance one chunk */
+ struct IDAT_list *cur = idat->idat_cur;
+
+ assert(idat->idat_index == idat->idat_length);
+ assert(cur != NULL && cur->count > 0);
+
+ /* NOTE: IDAT_list::count here, not IDAT_list::length */
+ if (++(idat->idat_count) >= cur->count)
+ {
+ assert(idat->idat_count == cur->count);
+
+ /* Move on to the next IDAT_list: */
+ cur = cur->next;
+
+ /* This is an internal error - read beyond the end of
+ * the pre-calculated stream.
+ */
+ if (cur == NULL || cur->count == 0)
+ stop(file, UNEXPECTED_ERROR_CODE,
+ "read beyond end of IDAT");
+
+ idat->idat_count = 0;
+ idat->idat_cur = cur;
+ }
+
+ idat->idat_index = 0;
+ /* Zero length IDAT chunks are permitted, so the length
+ * here may be 0.
+ */
+ idat->idat_length = cur->lengths[idat->idat_count];
+
+ /* And skip 12 bytes to the next chunk data */
+ skip_12(file);
+ }
+
+ /* The index is always that of the next byte, the rest of
+ * the information is always the current IDAT chunk and the
+ * current list.
+ */
+ ++(idat->idat_index);
+ }
+
+ /* Read the byte from the stream. */
+ b = reread_byte(file);
+
+ /* If the byte must be rewritten handle that here */
+ if (chunk->rewrite_length > 0)
+ {
+ if (chunk->rewrite_offset > 0)
+ --(chunk->rewrite_offset);
+
+ else
+ {
+ b = chunk->rewrite_buffer[0];
+ memmove(chunk->rewrite_buffer, chunk->rewrite_buffer+1,
+ (sizeof chunk->rewrite_buffer)-
+ (sizeof chunk->rewrite_buffer[0]));
+
+ --(chunk->rewrite_length);
+ }
+ }
+
+ chunk->write_crc = crc_one_byte(chunk->write_crc, b);
+ break;
+
+ /* The CRC is written at:
+ *
+ * chunk_write == chunk_length+8..chunk_length+11
+ *
+ * so 8 to 11. The CRC is not (yet) conditioned.
+ */
+ case 8: b = chunk->write_crc >> 24; goto write_crc;
+ case 9: b = chunk->write_crc >> 16; goto write_crc;
+ case 10: b = chunk->write_crc >> 8; goto write_crc;
+ case 11:
+ /* This must happen before the chunk_end below: */
+ b = chunk->write_crc;
+
+ if (file->global->verbose > 2)
+ {
+ fputs(" ", stderr);
+ type_name(type, stderr);
+ fprintf(stderr, " %lu 0x%.8x\n", (unsigned long)length,
+ chunk->write_crc ^ 0xffffffff);
+ }
+
+ /* The IDAT stream is written without a call to read_chunk
+ * until the end is reached. rechunk_length() calculates the
+ * length of the output chunks. Control gets to this point at
+ * the end of an *output* chunk - the length calculated by
+ * rechunk_length. If this corresponds to the end of the
+ * input stream stop writing IDAT chunks, otherwise continue.
+ */
+ if (file->state == STATE_IDAT &&
+ (file->idat->idat_index < file->idat->idat_length ||
+ 1+file->idat->idat_count < file->idat->idat_cur->count ||
+ file->idat->idat_cur != file->idat->idat_list_tail))
+ {
+ /* Write another IDAT chunk. Call rechunk_length to
+ * calculate the length required.
+ */
+ length = chunk->chunk_length = rechunk_length(file->idat);
+ assert(type == png_IDAT);
+ file->write_count = 0; /* for the new chunk */
+ --(file->write_count); /* fake out the increment below */
+ }
+
+ else
+ {
+ /* Entered at the end of a non-IDAT chunk and at the end of
+ * the IDAT stream. The rewrite should have been cleared.
+ */
+ if (chunk->rewrite_length > 0 || chunk->rewrite_offset > 0)
+ stop(file, UNEXPECTED_ERROR_CODE, "pending rewrite");
+
+ /* This is the last byte so reset chunk_read for the next
+ * chunk and move the input file to the position after the
+ * *next* chunk header if required.
+ */
+ file->read_count = 8;
+ file_setpos(file, &file->data_pos);
+
+ if (file->idat == NULL)
+ chunk_end(&file->chunk);
+
+ else
+ IDAT_end(&file->idat);
+ }
+
+ write_crc:
+ b ^= 0xff; /* conditioning */
+ break;
+ }
+ break;
+ }
+
+ /* Write one byte */
+ b &= 0xff;
+ *buffer++ = (png_byte)b;
+ --count;
+ write_byte(file, (png_byte)b); /* increments chunk_write */
+ }
+ while (count > 0);
+}
+
+/* Bundle the file and an uninitialized chunk and IDAT control structure
+ * together to allow implementation of the chunk/IDAT allocate routine.
+ */
+struct control
+{
+ struct file file;
+ struct chunk chunk;
+ struct IDAT idat;
+};
+
+static int
+control_end(struct control *control)
+{
+ return file_end(&control->file);
+}
+
+static struct file *
+get_control(png_const_structrp png_ptr)
+{
+ /* This just returns the (file*). The chunk and idat control structures
+ * don't always exist.
+ */
+ struct control *control = voidcast(struct control*,
+ png_get_error_ptr(png_ptr));
+ return &control->file;
+}
+
+static void
+allocate(struct file *file, int allocate_idat)
+{
+ struct control *control = voidcast(struct control*, file->alloc_ptr);
+
+ if (allocate_idat)
+ {
+ assert(file->idat == NULL);
+ IDAT_init(&control->idat, file);
+ }
+
+ else /* chunk */
+ {
+ assert(file->chunk == NULL);
+ chunk_init(&control->chunk, file);
+ }
+}
+
+static int
+control_init(struct control *control, struct global *global,
+ const char *file_name, const char *out_name)
+ /* This wraps file_init(&control::file) and simply returns the result from
+ * file_init.
+ */
+{
+ return file_init(&control->file, global, file_name, out_name, control,
+ allocate);
+}
+
+static int
+read_png(struct control *control)
+ /* Read a PNG, return 0 on success else an error (status) code; a bit mask as
+ * defined for file::status_code as above.
+ */
+{
+ png_structp png_ptr;
+ png_infop info_ptr = NULL;
+ volatile int rc;
+
+ png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, control,
+ error_handler, warning_handler);
+
+ if (png_ptr == NULL)
+ {
+ /* This is not really expected. */
+ log_error(&control->file, LIBPNG_ERROR_CODE, "OOM allocating png_struct");
+ control->file.status_code |= INTERNAL_ERROR;
+ return LIBPNG_ERROR_CODE;
+ }
+
+ rc = setjmp(control->file.jmpbuf);
+ if (rc == 0)
+ {
+# ifdef PNG_SET_USER_LIMITS_SUPPORTED
+ /* Remove any limits on the size of PNG files that can be read,
+ * without this we may reject files based on built-in safety
+ * limits.
+ */
+ png_set_user_limits(png_ptr, 0x7fffffff, 0x7fffffff);
+ png_set_chunk_cache_max(png_ptr, 0);
+ png_set_chunk_malloc_max(png_ptr, 0);
+# endif
+
+ png_set_read_fn(png_ptr, control, read_callback);
+
+ info_ptr = png_create_info_struct(png_ptr);
+ if (info_ptr == NULL)
+ png_error(png_ptr, "OOM allocating info structure");
+
+ if (control->file.global->verbose)
+ fprintf(stderr, " INFO\n");
+
+ png_read_info(png_ptr, info_ptr);
+
+ {
+ png_uint_32 height = png_get_image_height(png_ptr, info_ptr);
+ int passes = png_set_interlace_handling(png_ptr);
+ int pass;
+
+ png_start_read_image(png_ptr);
+
+ for (pass = 0; pass < passes; ++pass)
+ {
+ png_uint_32 y = height;
+
+ /* NOTE: this skips asking libpng to return either version of
+ * the image row, but libpng still reads the rows.
+ */
+ while (y-- > 0)
+ png_read_row(png_ptr, NULL, NULL);
+ }
+ }
+
+ if (control->file.global->verbose)
+ fprintf(stderr, " END\n");
+
+ /* Make sure to read to the end of the file: */
+ png_read_end(png_ptr, info_ptr);
+ }
+
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+ return rc;
+}
+
+static int
+one_file(struct global *global, const char *file_name, const char *out_name)
+{
+ int rc;
+ struct control control;
+
+ if (global->verbose)
+ fprintf(stderr, "FILE %s -> %s\n", file_name,
+ out_name ? out_name : "<none>");
+
+ /* Although control_init can return a failure code the structure is always
+ * initialized, so control_end can be used to accumulate any status codes.
+ */
+ rc = control_init(&control, global, file_name, out_name);
+
+ if (rc == 0)
+ rc = read_png(&control);
+
+ rc |= control_end(&control);
+
+ return rc;
+}
+
+static void
+usage(const char *prog)
+{
+ /* ANSI C-90 limits strings to 509 characters, so use a string array: */
+ size_t i;
+ static const char *usage_string[] = {
+" Tests, optimizes and optionally fixes the zlib header in PNG files.",
+" Optionally, when fixing, strips ancilliary chunks from the file.",
+0,
+"OPTIONS",
+" OPERATION",
+" By default files are just checked for readability with a summary of the",
+" of zlib issues founds for each compressed chunk and the IDAT stream in",
+" the file.",
+" --optimize (-o):",
+" Find the smallest deflate window size for the compressed data.",
+" --strip=[none|crc|unsafe|unused|transform|color|all]:",
+" none (default): Retain all chunks.",
+" crc: Remove chunks with a bad CRC.",
+" unsafe: Remove chunks that may be unsafe to retain if the image data",
+" is modified. This is set automatically if --max is given but",
+" may be cancelled by a later --strip=none.",
+" unused: Remove chunks not used by libpng when decoding an image.",
+" This retains any chunks that might be used by libpng image",
+" transformations.",
+" transform: unused+bKGD.",
+" color: transform+iCCP and cHRM.",
+" all: color+gAMA and sRGB.",
+" Only ancillary chunks are ever removed. In addition the tRNS and sBIT",
+" chunks are never removed as they affect exact interpretation of the",
+" image pixel values. The following known chunks are treated specially",
+" by the above options:",
+" gAMA, sRGB [all]: These specify the gamma encoding used for the pixel",
+" values.",
+" cHRM, iCCP [color]: These specify how colors are encoded. iCCP also",
+" specifies the exact encoding of a pixel value; however, in",
+" practice most programs will ignore it.",
+" bKGD [transform]: This is used by libpng transforms."
+" --max=<number>:",
+" Use IDAT chunks sized <number>. If no number is given the the IDAT",
+" chunks will be the maximum size permitted; 2^31-1 bytes. If the option",
+" is omitted the original chunk sizes will not be changed. When the",
+" option is given --strip=unsafe is set automatically. This may be",
+" cancelled if you know that all unknown unsafe-to-copy chunks really are",
+" safe to copy across an IDAT size change. This is true of all chunks",
+" that have ever been formally proposed as PNG extensions.",
+" MESSAGES",
+" By default the program only outputs summaries for each file.",
+" --quiet (-q):",
+" Do not output the summaries except for files that cannot be read. With",
+" two --quiets these are not output either.",
+" --errors (-e):",
+" Output errors from libpng and the program (except too-far-back).",
+" --warnings (-w):",
+" Output warnings from libpng.",
+" OUTPUT",
+" By default nothing is written.",
+" --out=<file>:",
+" Write the optimized/corrected version of the next PNG to <file>. This",
+" overrides the following two options",
+" --suffix=<suffix>:",
+" Set --out=<name><suffix> for all following files unless overridden on",
+" a per-file basis by explicit --out.",
+" --prefix=<prefix>:",
+" Set --out=<prefix><name> for all the following files unless overridden",
+" on a per-file basis by explicit --out.",
+" These two options can be used together to produce a suffix and prefix.",
+" INTERNAL OPTIONS",
+#if 0 /*NYI*/
+#ifdef PNG_MAXIMUM_INFLATE_WINDOW
+" --test:",
+" Test the PNG_MAXIMUM_INFLATE_WINDOW option. Setting this disables",
+" output as this would produce a broken file.",
+#endif
+#endif
+0,
+"EXIT CODES",
+" *** SUBJECT TO CHANGE ***",
+" The program exit code is value in the range 0..127 holding a bit mask of",
+" the following codes. Notice that the results for each file are combined",
+" together - check one file at a time to get a meaningful error code!",
+" 0x01: The zlib too-far-back error existed in at least one chunk.",
+" 0x02: At least one chunk had a CRC error.",
+" 0x04: A chunk length was incorrect.",
+" 0x08: The file was truncated.",
+" Errors less than 16 are potentially recoverable, for a single file if the",
+" exit code is less than 16 the file could be read (with corrections if a",
+" non-zero code is returned).",
+" 0x10: The file could not be read, even with corrections.",
+" 0x20: The output file could not be written.",
+" 0x40: An unexpected, potentially internal, error occurred.",
+" If the command line arguments are incorrect the program exits with exit",
+" 255. Some older operating systems only support 7-bit exit codes, on those",
+" systems it is suggested that this program is first tested by supplying",
+" invalid arguments.",
+0,
+"DESCRIPTION",
+" " PROGRAM_NAME ":",
+" checks each PNG file on the command line for errors. By default errors are",
+" not output and the program just returns an exit code and prints a summary.",
+" With the --quiet (-q) option the summaries are suppressed too and the",
+" program only outputs unexpected errors (internal errors and file open",
+" errors).",
+" Various known problems in PNG files are fixed while the file is being read",
+" The exit code says what problems were fixed. In particular the zlib error:",
+0,
+" \"invalid distance too far back\"",
+0,
+" caused by an incorrect optimization of a zlib stream is fixed in any",
+" compressed chunk in which it is encountered. An integrity problem of the",
+" PNG stream caused by a bug in libpng which wrote an incorrect chunk length",
+" is also fixed. Chunk CRC errors are automatically fixed up.",
+0,
+" Setting one of the \"OUTPUT\" options causes the possibly modified file to",
+" be written to a new file.",
+0,
+" Notice that some PNG files with the zlib optimization problem can still be",
+" read by libpng under some circumstances. This program will still detect",
+" and, if requested, correct the error.",
+0,
+" The program will reliably process all files on the command line unless",
+" either an invalid argument causes the usage message (this message) to be",
+" produced or the program crashes.",
+0,
+" The summary lines describe issues encountered with the zlib compressed",
+" stream of a chunk. They have the following format, which is SUBJECT TO",
+" CHANGE in the future:",
+0,
+" chunk reason comp-level p1 p2 p3 p4 file",
+0,
+" p1 through p4 vary according to the 'reason'. There are always 8 space",
+" separated fields. Reasons specific formats are:",
+0,
+" chunk ERR status code read-errno write-errno message file",
+" chunk SKP comp-level file-bits zlib-rc compressed message file",
+" chunk ??? comp-level file-bits ok-bits compressed uncompress file",
+0,
+" The various fields are",
+0,
+"$1 chunk: The chunk type of a chunk in the file or 'HEAD' if a problem",
+" is reported by libpng at the start of the IDAT stream.",
+"$2 reason: One of:",
+" CHK: A zlib header checksum was detected and fixed.",
+" TFB: The zlib too far back error was detected and fixed.",
+" OK : No errors were detected in the zlib stream and optimization",
+" was not requested, or was not possible.",
+" OPT: The zlib stream window bits value could be improved (and was).",
+" SKP: The chunk was skipped because of a zlib issue (zlib-rc) with",
+" explanation 'message'",
+" ERR: The read of the file was aborted. The parameters explain why.",
+"$3 status: For 'ERR' the accumulated status code from 'EXIT CODES' above.",
+" This is printed as a 2 digit hexadecimal value",
+" comp-level: The recorded compression level (FLEVEL) of a zlib stream",
+" expressed as a string {supfast,stdfast,default,maximum}",
+"$4 code: The file exit code; where stop was called, as a fairly terse",
+" string {warning,libpng,zlib,invalid,read,write,unexpected}.",
+" file-bits: The zlib window bits recorded in the file.",
+"$5 read-errno: A system errno value from a read translated by strerror(3).",
+" zlib-rc: A zlib return code as a string (see zlib.h).",
+" ok-bits: The smallest zlib window bits value that works.",
+"$6 write-errno:A system errno value from a write translated by strerror(3).",
+" compressed: The count of compressed bytes in the zlib stream, when the",
+" reason is 'SKP'; this is a count of the bytes read from the",
+" stream when the fatal error was encountered.",
+"$7 message: An error message (spaces replaced by _, as in all parameters),",
+" uncompress: The count of bytes from uncompressing the zlib stream; this",
+" may not be the same as the number of bytes in the image.",
+"$8 file: The name of the file (this may contain spaces).",
+};
+
+ fprintf(stderr, "Usage: %s {[options] png-file}\n", prog);
+
+ for (i=0; i < (sizeof usage_string)/(sizeof usage_string[0]); ++i)
+ {
+ if (usage_string[i] != 0)
+ fputs(usage_string[i], stderr);
+
+ fputc('\n', stderr);
+ }
+
+ exit(255);
+}
+
+int
+main(int argc, const char **argv)
+{
+ char temp_name[FILENAME_MAX+1];
+ const char * prog = *argv;
+ const char * outfile = NULL;
+ const char * suffix = NULL;
+ const char * prefix = NULL;
+ int done = 0; /* if at least one file is processed */
+ struct global global;
+
+ global_init(&global);
+
+ while (--argc > 0)
+ {
+ ++argv;
+
+ if (strcmp(*argv, "--debug") == 0)
+ {
+ /* To help debugging problems: */
+ global.errors = global.warnings = 1;
+ global.quiet = 0;
+ global.verbose = 7;
+ }
+
+ else if (strncmp(*argv, "--max=", 6) == 0)
+ {
+ global.idat_max = (png_uint_32)atol(6+*argv);
+
+ if (global.skip < SKIP_UNSAFE)
+ global.skip = SKIP_UNSAFE;
+ }
+
+ else if (strcmp(*argv, "--max") == 0)
+ {
+ global.idat_max = 0x7fffffff;
+
+ if (global.skip < SKIP_UNSAFE)
+ global.skip = SKIP_UNSAFE;
+ }
+
+ else if (strcmp(*argv, "--optimize") == 0 || strcmp(*argv, "-o") == 0)
+ global.optimize_zlib = 1;
+
+ else if (strncmp(*argv, "--out=", 6) == 0)
+ outfile = 6+*argv;
+
+ else if (strncmp(*argv, "--suffix=", 9) == 0)
+ suffix = 9+*argv;
+
+ else if (strncmp(*argv, "--prefix=", 9) == 0)
+ prefix = 9+*argv;
+
+ else if (strcmp(*argv, "--strip=none") == 0)
+ global.skip = SKIP_NONE;
+
+ else if (strcmp(*argv, "--strip=crc") == 0)
+ global.skip = SKIP_BAD_CRC;
+
+ else if (strcmp(*argv, "--strip=unsafe") == 0)
+ global.skip = SKIP_UNSAFE;
+
+ else if (strcmp(*argv, "--strip=unused") == 0)
+ global.skip = SKIP_UNUSED;
+
+ else if (strcmp(*argv, "--strip=transform") == 0)
+ global.skip = SKIP_TRANSFORM;
+
+ else if (strcmp(*argv, "--strip=color") == 0)
+ global.skip = SKIP_COLOR;
+
+ else if (strcmp(*argv, "--strip=all") == 0)
+ global.skip = SKIP_ALL;
+
+ else if (strcmp(*argv, "--errors") == 0 || strcmp(*argv, "-e") == 0)
+ global.errors = 1;
+
+ else if (strcmp(*argv, "--warnings") == 0 || strcmp(*argv, "-w") == 0)
+ global.warnings = 1;
+
+ else if (strcmp(*argv, "--quiet") == 0 || strcmp(*argv, "-q") == 0)
+ {
+ if (global.quiet)
+ global.quiet = 2;
+
+ else
+ global.quiet = 1;
+ }
+
+ else if (strcmp(*argv, "--verbose") == 0 || strcmp(*argv, "-v") == 0)
+ ++global.verbose;
+
+#if 0
+ /* NYI */
+# ifdef PNG_MAXIMUM_INFLATE_WINDOW
+ else if (strcmp(*argv, "--test") == 0)
+ ++set_option;
+# endif
+#endif
+
+ else if ((*argv)[0] == '-')
+ usage(prog);
+
+ else
+ {
+ size_t outlen = strlen(*argv);
+
+ if (outfile == NULL) /* else this takes precedence */
+ {
+ /* Consider the prefix/suffix options */
+ if (prefix != NULL)
+ {
+ size_t prefixlen = strlen(prefix);
+
+ if (prefixlen+outlen > FILENAME_MAX)
+ {
+ fprintf(stderr, "%s: output file name too long: %s%s%s\n",
+ prog, prefix, *argv, suffix ? suffix : "");
+ global.status_code |= WRITE_ERROR;
+ continue;
+ }
+
+ memcpy(temp_name, prefix, prefixlen);
+ memcpy(temp_name+prefixlen, *argv, outlen);
+ outlen += prefixlen;
+ outfile = temp_name;
+ }
+
+ else if (suffix != NULL)
+ memcpy(temp_name, *argv, outlen);
+
+ temp_name[outlen] = 0;
+
+ if (suffix != NULL)
+ {
+ size_t suffixlen = strlen(suffix);
+
+ if (outlen+suffixlen > FILENAME_MAX)
+ {
+ fprintf(stderr, "%s: output file name too long: %s%s\n",
+ prog, *argv, suffix);
+ global.status_code |= WRITE_ERROR;
+ continue;
+ }
+
+ memcpy(temp_name+outlen, suffix, suffixlen);
+ outlen += suffixlen;
+ temp_name[outlen] = 0;
+ outfile = temp_name;
+ }
+ }
+
+ (void)one_file(&global, *argv, outfile);
+ ++done;
+ outfile = NULL;
+ }
+ }
+
+ if (!done)
+ usage(prog);
+
+ return global_end(&global);
+}
+
+#else /* ZLIB_VERNUM < 0x1240 */
+int
+main(void)
+{
+ fprintf(stderr,
+ "pngfix needs libpng with a zlib >=1.2.4 (not 0x%x)\n",
+ ZLIB_VERNUM);
+ return 77;
+}
+#endif /* ZLIB_VERNUM */
+
+#else /* No read support */
+
+int
+main(void)
+{
+ fprintf(stderr, "pngfix does not work without read deinterlace support\n");
+ return 77;
+}
+#endif /* PNG_READ_SUPPORTED && PNG_EASY_ACCESS_SUPPORTED */
+#else /* No setjmp support */
+int
+main(void)
+{
+ fprintf(stderr, "pngfix does not work without setjmp support\n");
+ return 77;
+}
+#endif /* PNG_SETJMP_SUPPORTED */
+
diff --git a/libpng/contrib/tools/sRGB.h b/libpng/contrib/tools/sRGB.h
new file mode 100644
index 0000000..22c8f7c
--- /dev/null
+++ b/libpng/contrib/tools/sRGB.h
@@ -0,0 +1,48 @@
+/*-
+ * sRGB.h
+ *
+ * Last changed in libpng 1.6.0 [February 14, 2013]
+ *
+ * COPYRIGHT: Written by John Cunningham Bowler, 2013.
+ * To the extent possible under law, the author has waived all copyright and
+ * related or neighboring rights to this work. This work is published from:
+ * United States.
+ *
+ * Utility file; not actually a header, this contains definitions of sRGB
+ * calculation functions for inclusion in those test programs that need them.
+ *
+ * All routines take and return a floating point value in the range
+ * 0 to 1.0, doing a calculation according to the sRGB specification
+ * (in fact the source of the numbers is the wikipedia article at
+ * http://en.wikipedia.org/wiki/SRGB).
+ */
+static double
+sRGB_from_linear(double l)
+{
+ if (l <= 0.0031308)
+ l *= 12.92;
+
+ else
+ l = 1.055 * pow(l, 1/2.4) - 0.055;
+
+ return l;
+}
+
+static double
+linear_from_sRGB(double s)
+{
+ if (s <= 0.04045)
+ return s / 12.92;
+
+ else
+ return pow((s+0.055)/1.055, 2.4);
+}
+
+static double
+YfromRGB(double r, double g, double b)
+{
+ /* Use the sRGB (rounded) coefficients for Rlinear, Glinear, Blinear to get
+ * the CIE Y value (also linear).
+ */
+ return 0.2126 * r + 0.7152 * g + 0.0722 * b;
+}
diff --git a/libpng/contrib/visupng/PngFile.c b/libpng/contrib/visupng/PngFile.c
new file mode 100644
index 0000000..dcde18a
--- /dev/null
+++ b/libpng/contrib/visupng/PngFile.c
@@ -0,0 +1,451 @@
+/*-------------------------------------
+ * PNGFILE.C -- Image File Functions
+ *-------------------------------------
+ *
+ * Copyright 2000, Willem van Schaik.
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ */
+
+#include <windows.h>
+#include <commdlg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <zlib.h>
+
+#include "png.h"
+#include "pngfile.h"
+#include "cexcept.h"
+
+define_exception_type(const char *);
+extern struct exception_context the_exception_context[1];
+struct exception_context the_exception_context[1];
+png_const_charp msg;
+
+static OPENFILENAME ofn;
+
+static png_structp png_ptr = NULL;
+static png_infop info_ptr = NULL;
+
+
+/* cexcept interface */
+
+static void
+png_cexcept_error(png_structp png_ptr, png_const_charp msg)
+{
+ if(png_ptr)
+ ;
+#ifdef PNG_CONSOLE_IO_SUPPORTED
+ fprintf(stderr, "libpng error: %s\n", msg);
+#endif
+ {
+ Throw msg;
+ }
+}
+
+/* Windows open-file functions */
+
+void PngFileInitialize (HWND hwnd)
+{
+ static TCHAR szFilter[] = TEXT ("PNG Files (*.PNG)\0*.png\0")
+ TEXT ("All Files (*.*)\0*.*\0\0");
+
+ ofn.lStructSize = sizeof (OPENFILENAME);
+ ofn.hwndOwner = hwnd;
+ ofn.hInstance = NULL;
+ ofn.lpstrFilter = szFilter;
+ ofn.lpstrCustomFilter = NULL;
+ ofn.nMaxCustFilter = 0;
+ ofn.nFilterIndex = 0;
+ ofn.lpstrFile = NULL; /* Set in Open and Close functions */
+ ofn.nMaxFile = MAX_PATH;
+ ofn.lpstrFileTitle = NULL; /* Set in Open and Close functions */
+ ofn.nMaxFileTitle = MAX_PATH;
+ ofn.lpstrInitialDir = NULL;
+ ofn.lpstrTitle = NULL;
+ ofn.Flags = 0; /* Set in Open and Close functions */
+ ofn.nFileOffset = 0;
+ ofn.nFileExtension = 0;
+ ofn.lpstrDefExt = TEXT ("png");
+ ofn.lCustData = 0;
+ ofn.lpfnHook = NULL;
+ ofn.lpTemplateName = NULL;
+}
+
+BOOL PngFileOpenDlg (HWND hwnd, PTSTR pstrFileName, PTSTR pstrTitleName)
+{
+ ofn.hwndOwner = hwnd;
+ ofn.lpstrFile = pstrFileName;
+ ofn.lpstrFileTitle = pstrTitleName;
+ ofn.Flags = OFN_HIDEREADONLY;
+
+ return GetOpenFileName (&ofn);
+}
+
+BOOL PngFileSaveDlg (HWND hwnd, PTSTR pstrFileName, PTSTR pstrTitleName)
+{
+ ofn.hwndOwner = hwnd;
+ ofn.lpstrFile = pstrFileName;
+ ofn.lpstrFileTitle = pstrTitleName;
+ ofn.Flags = OFN_HIDEREADONLY | OFN_OVERWRITEPROMPT;
+
+ return GetSaveFileName (&ofn);
+}
+
+/* PNG image handler functions */
+
+BOOL PngLoadImage (PTSTR pstrFileName, png_byte **ppbImageData,
+ int *piWidth, int *piHeight, int *piChannels, png_color *pBkgColor)
+{
+ static FILE *pfFile;
+ png_byte pbSig[8];
+ int iBitDepth;
+ int iColorType;
+ double dGamma;
+ png_color_16 *pBackground;
+ png_uint_32 ulChannels;
+ png_uint_32 ulRowBytes;
+ png_byte *pbImageData = *ppbImageData;
+ static png_byte **ppbRowPointers = NULL;
+ int i;
+
+ /* open the PNG input file */
+
+ if (!pstrFileName)
+ {
+ *ppbImageData = pbImageData = NULL;
+ return FALSE;
+ }
+
+ if (!(pfFile = fopen(pstrFileName, "rb")))
+ {
+ *ppbImageData = pbImageData = NULL;
+ return FALSE;
+ }
+
+ /* first check the eight byte PNG signature */
+
+ fread(pbSig, 1, 8, pfFile);
+ if (png_sig_cmp(pbSig, 0, 8))
+ {
+ *ppbImageData = pbImageData = NULL;
+ return FALSE;
+ }
+
+ /* create the two png(-info) structures */
+
+ png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL,
+ (png_error_ptr)png_cexcept_error, (png_error_ptr)NULL);
+ if (!png_ptr)
+ {
+ *ppbImageData = pbImageData = NULL;
+ return FALSE;
+ }
+
+ info_ptr = png_create_info_struct(png_ptr);
+ if (!info_ptr)
+ {
+ png_destroy_read_struct(&png_ptr, NULL, NULL);
+ *ppbImageData = pbImageData = NULL;
+ return FALSE;
+ }
+
+ Try
+ {
+
+ /* initialize the png structure */
+
+#ifdef PNG_STDIO_SUPPORTED
+ png_init_io(png_ptr, pfFile);
+#else
+ png_set_read_fn(png_ptr, (png_voidp)pfFile, png_read_data);
+#endif
+
+ png_set_sig_bytes(png_ptr, 8);
+
+ /* read all PNG info up to image data */
+
+ png_read_info(png_ptr, info_ptr);
+
+ /* get width, height, bit-depth and color-type */
+
+ png_get_IHDR(png_ptr, info_ptr, piWidth, piHeight, &iBitDepth,
+ &iColorType, NULL, NULL, NULL);
+
+ /* expand images of all color-type and bit-depth to 3x8-bit RGB */
+ /* let the library process alpha, transparency, background, etc. */
+
+#ifdef PNG_READ_16_TO_8_SUPPORTED
+ if (iBitDepth == 16)
+# ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
+ png_set_scale_16(png_ptr);
+# else
+ png_set_strip_16(png_ptr);
+# endif
+#endif
+ if (iColorType == PNG_COLOR_TYPE_PALETTE)
+ png_set_expand(png_ptr);
+ if (iBitDepth < 8)
+ png_set_expand(png_ptr);
+ if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
+ png_set_expand(png_ptr);
+ if (iColorType == PNG_COLOR_TYPE_GRAY ||
+ iColorType == PNG_COLOR_TYPE_GRAY_ALPHA)
+ png_set_gray_to_rgb(png_ptr);
+
+ /* set the background color to draw transparent and alpha images over */
+ if (png_get_bKGD(png_ptr, info_ptr, &pBackground))
+ {
+ png_set_background(png_ptr, pBackground, PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
+ pBkgColor->red = (byte) pBackground->red;
+ pBkgColor->green = (byte) pBackground->green;
+ pBkgColor->blue = (byte) pBackground->blue;
+ }
+ else
+ {
+ pBkgColor = NULL;
+ }
+
+ /* if required set gamma conversion */
+ if (png_get_gAMA(png_ptr, info_ptr, &dGamma))
+ png_set_gamma(png_ptr, (double) 2.2, dGamma);
+
+ /* after the transformations are registered, update info_ptr data */
+
+ png_read_update_info(png_ptr, info_ptr);
+
+ /* get again width, height and the new bit-depth and color-type */
+
+ png_get_IHDR(png_ptr, info_ptr, piWidth, piHeight, &iBitDepth,
+ &iColorType, NULL, NULL, NULL);
+
+
+ /* row_bytes is the width x number of channels */
+
+ ulRowBytes = png_get_rowbytes(png_ptr, info_ptr);
+ ulChannels = png_get_channels(png_ptr, info_ptr);
+
+ *piChannels = ulChannels;
+
+ /* now we can allocate memory to store the image */
+
+ if (pbImageData)
+ {
+ free (pbImageData);
+ pbImageData = NULL;
+ }
+ if ((pbImageData = (png_byte *) malloc(ulRowBytes * (*piHeight)
+ * sizeof(png_byte))) == NULL)
+ {
+ png_error(png_ptr, "Visual PNG: out of memory");
+ }
+ *ppbImageData = pbImageData;
+
+ /* and allocate memory for an array of row-pointers */
+
+ if ((ppbRowPointers = (png_bytepp) malloc((*piHeight)
+ * sizeof(png_bytep))) == NULL)
+ {
+ png_error(png_ptr, "Visual PNG: out of memory");
+ }
+
+ /* set the individual row-pointers to point at the correct offsets */
+
+ for (i = 0; i < (*piHeight); i++)
+ ppbRowPointers[i] = pbImageData + i * ulRowBytes;
+
+ /* now we can go ahead and just read the whole image */
+
+ png_read_image(png_ptr, ppbRowPointers);
+
+ /* read the additional chunks in the PNG file (not really needed) */
+
+ png_read_end(png_ptr, NULL);
+
+ /* and we're done */
+
+ free (ppbRowPointers);
+ ppbRowPointers = NULL;
+
+ /* yepp, done */
+ }
+
+ Catch (msg)
+ {
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+
+ *ppbImageData = pbImageData = NULL;
+
+ if(ppbRowPointers)
+ free (ppbRowPointers);
+
+ fclose(pfFile);
+
+ return FALSE;
+ }
+
+ fclose (pfFile);
+
+ return TRUE;
+}
+
+
+BOOL PngSaveImage (PTSTR pstrFileName, png_byte *pDiData,
+ int iWidth, int iHeight, png_color bkgColor)
+{
+ const int ciBitDepth = 8;
+ const int ciChannels = 3;
+
+ static FILE *pfFile;
+ png_uint_32 ulRowBytes;
+ static png_byte **ppbRowPointers = NULL;
+ int i;
+
+ /* open the PNG output file */
+
+ if (!pstrFileName)
+ return FALSE;
+
+ if (!(pfFile = fopen(pstrFileName, "wb")))
+ return FALSE;
+
+ /* prepare the standard PNG structures */
+
+ png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL,
+ (png_error_ptr)png_cexcept_error, (png_error_ptr)NULL);
+ if (!png_ptr)
+ {
+ fclose(pfFile);
+ return FALSE;
+ }
+
+ info_ptr = png_create_info_struct(png_ptr);
+ if (!info_ptr) {
+ fclose(pfFile);
+ png_destroy_write_struct(&png_ptr, (png_infopp) NULL);
+ return FALSE;
+ }
+
+ Try
+ {
+ /* initialize the png structure */
+
+#ifdef PNG_STDIO_SUPPORTED
+ png_init_io(png_ptr, pfFile);
+#else
+ png_set_write_fn(png_ptr, (png_voidp)pfFile, png_write_data, png_flush);
+#endif
+
+ /* we're going to write a very simple 3x8-bit RGB image */
+
+ png_set_IHDR(png_ptr, info_ptr, iWidth, iHeight, ciBitDepth,
+ PNG_COLOR_TYPE_RGB, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE,
+ PNG_FILTER_TYPE_BASE);
+
+ /* write the file header information */
+
+ png_write_info(png_ptr, info_ptr);
+
+ /* swap the BGR pixels in the DiData structure to RGB */
+
+ png_set_bgr(png_ptr);
+
+ /* row_bytes is the width x number of channels */
+
+ ulRowBytes = iWidth * ciChannels;
+
+ /* we can allocate memory for an array of row-pointers */
+
+ if ((ppbRowPointers = (png_bytepp) malloc(iHeight * sizeof(png_bytep))) == NULL)
+ Throw "Visualpng: Out of memory";
+
+ /* set the individual row-pointers to point at the correct offsets */
+
+ for (i = 0; i < iHeight; i++)
+ ppbRowPointers[i] = pDiData + i * (((ulRowBytes + 3) >> 2) << 2);
+
+ /* write out the entire image data in one call */
+
+ png_write_image (png_ptr, ppbRowPointers);
+
+ /* write the additional chunks to the PNG file (not really needed) */
+
+ png_write_end(png_ptr, info_ptr);
+
+ /* and we're done */
+
+ free (ppbRowPointers);
+ ppbRowPointers = NULL;
+
+ /* clean up after the write, and free any memory allocated */
+
+ png_destroy_write_struct(&png_ptr, (png_infopp) NULL);
+
+ /* yepp, done */
+ }
+
+ Catch (msg)
+ {
+ png_destroy_write_struct(&png_ptr, (png_infopp) NULL);
+
+ if(ppbRowPointers)
+ free (ppbRowPointers);
+
+ fclose(pfFile);
+
+ return FALSE;
+ }
+
+ fclose (pfFile);
+
+ return TRUE;
+}
+
+#ifndef PNG_STDIO_SUPPORTED
+
+static void
+png_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
+{
+ png_size_t check;
+
+ /* fread() returns 0 on error, so it is OK to store this in a png_size_t
+ * instead of an int, which is what fread() actually returns.
+ */
+ check = (png_size_t)fread(data, (png_size_t)1, length,
+ (FILE *)png_ptr->io_ptr);
+
+ if (check != length)
+ {
+ png_error(png_ptr, "Read Error");
+ }
+}
+
+static void
+png_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
+{
+ png_uint_32 check;
+
+ check = fwrite(data, 1, length, (FILE *)(png_ptr->io_ptr));
+ if (check != length)
+ {
+ png_error(png_ptr, "Write Error");
+ }
+}
+
+static void
+png_flush(png_structp png_ptr)
+{
+ FILE *io_ptr;
+ io_ptr = (FILE *)CVT_PTR((png_ptr->io_ptr));
+ if (io_ptr != NULL)
+ fflush(io_ptr);
+}
+
+#endif
+
+/*-----------------
+ * end of source
+ *-----------------
+ */
diff --git a/libpng/contrib/visupng/PngFile.h b/libpng/contrib/visupng/PngFile.h
new file mode 100644
index 0000000..474426c
--- /dev/null
+++ b/libpng/contrib/visupng/PngFile.h
@@ -0,0 +1,30 @@
+/*------------------------------------------*/
+/* PNGFILE.H -- Header File for pngfile.c*/
+/*------------------------------------------*/
+
+/* Copyright 2000, Willem van Schaik.*/
+
+/* This code is released under the libpng license.*/
+/* For conditions of distribution and use, see the disclaimer*/
+/* and license in png.h*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <windows.h>
+
+void PngFileInitialize (HWND hwnd) ;
+BOOL PngFileOpenDlg (HWND hwnd, PTSTR pstrFileName, PTSTR pstrTitleName) ;
+BOOL PngFileSaveDlg (HWND hwnd, PTSTR pstrFileName, PTSTR pstrTitleName) ;
+
+BOOL PngLoadImage (PTSTR pstrFileName, png_byte **ppbImageData,
+ int *piWidth, int *piHeight, int *piChannels, png_color *pBkgColor);
+BOOL PngSaveImage (PTSTR pstrFileName, png_byte *pDiData,
+ int iWidth, int iHeight, png_color BkgColor);
+
+#ifndef PNG_STDIO_SUPPORTED
+static void png_read_data(png_structp png_ptr, png_bytep data, png_size_t length);
+static void png_write_data(png_structp png_ptr, png_bytep data, png_size_t length);
+static void png_flush(png_structp png_ptr);
+#endif
+
diff --git a/libpng/contrib/visupng/README.txt b/libpng/contrib/visupng/README.txt
new file mode 100644
index 0000000..72c5cba
--- /dev/null
+++ b/libpng/contrib/visupng/README.txt
@@ -0,0 +1,61 @@
+Microsoft Developer Studio Build File, Format Version 6.00 for VisualPng
+------------------------------------------------------------------------
+
+Copyright 2000, Willem van Schaik.
+
+This code is released under the libpng license.
+For conditions of distribution and use, see the disclaimer
+and license in png.h
+
+As a PNG .dll demo VisualPng is finished. More features would only hinder
+the program's objective. However, further extensions (like support for other
+graphics formats) are in development. To get these, or for pre-compiled
+binaries, go to "http://www.schaik.com/png/visualpng.html".
+
+------------------------------------------------------------------------
+
+Assumes that
+
+ libpng DLLs and LIBs are in ..\..\projects\msvc\win32\libpng
+ zlib DLLs and LIBs are in ..\..\projects\msvc\win32\zlib
+ libpng header files are in ..\..\..\libpng
+ zlib header files are in ..\..\..\zlib
+ the pngsuite images are in ..\pngsuite
+
+To build:
+
+1) On the main menu Select "Build|Set Active configuration".
+ Choose the configuration that corresponds to the library you want to test.
+ This library must have been built using the libpng MS project located in
+ the "..\..\mscv" subdirectory.
+
+2) Select "Build|Clean"
+
+3) Select "Build|Rebuild All"
+
+4) After compiling and linking VisualPng will be started to view an image
+ from the PngSuite directory. Press Ctrl-N (and Ctrl-V) for other images.
+
+
+To install:
+
+When distributing VisualPng (or a further development) the following options
+are available:
+
+1) Build the program with the configuration "Win32 LIB" and you only need to
+ include the executable from the ./lib directory in your distribution.
+
+2) Build the program with the configuration "Win32 DLL" and you need to put
+ in your distribution the executable from the ./dll directory and the dll's
+ libpng1.dll, zlib.dll and msvcrt.dll. These need to be in the user's PATH.
+
+
+Willem van Schaik
+Calgary, June 6th 2000
+
+P.S. VisualPng was written based on preliminary work of:
+
+ - Simon-Pierre Cadieux
+ - Glenn Randers-Pehrson
+ - Greg Roelofs
+
diff --git a/libpng/contrib/visupng/VisualPng.c b/libpng/contrib/visupng/VisualPng.c
new file mode 100644
index 0000000..236525a
--- /dev/null
+++ b/libpng/contrib/visupng/VisualPng.c
@@ -0,0 +1,970 @@
+/*------------------------------------
+ * VisualPng.C -- Shows a PNG image
+ *------------------------------------
+ *
+ * Copyright 2000, Willem van Schaik.
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ */
+
+/* switches */
+
+/* defines */
+
+#define PROGNAME "VisualPng"
+#define LONGNAME "Win32 Viewer for PNG-files"
+#define VERSION "1.0 of 2000 June 07"
+
+/* constants */
+
+#define MARGIN 8
+
+/* standard includes */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <windows.h>
+#include <zlib.h>
+
+/* application includes */
+
+#include "png.h"
+#include "pngfile.h"
+#include "resource.h"
+
+/* macros */
+
+/* function prototypes */
+
+LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM);
+BOOL CALLBACK AboutDlgProc (HWND, UINT, WPARAM, LPARAM) ;
+
+BOOL CenterAbout (HWND hwndChild, HWND hwndParent);
+
+BOOL BuildPngList (PTSTR pstrPathName, TCHAR **ppFileList, int *pFileCount,
+ int *pFileIndex);
+
+BOOL SearchPngList (TCHAR *pFileList, int FileCount, int *pFileIndex,
+ PTSTR pstrPrevName, PTSTR pstrNextName);
+
+BOOL LoadImageFile(HWND hwnd, PTSTR pstrPathName,
+ png_byte **ppbImage, int *pxImgSize, int *pyImgSize, int *piChannels,
+ png_color *pBkgColor);
+
+BOOL DisplayImage (HWND hwnd, BYTE **ppDib,
+ BYTE **ppDiData, int cxWinSize, int cyWinSize,
+ BYTE *pbImage, int cxImgSize, int cyImgSize, int cImgChannels,
+ BOOL bStretched);
+
+BOOL InitBitmap (
+ BYTE *pDiData, int cxWinSize, int cyWinSize);
+
+BOOL FillBitmap (
+ BYTE *pDiData, int cxWinSize, int cyWinSize,
+ BYTE *pbImage, int cxImgSize, int cyImgSize, int cImgChannels,
+ BOOL bStretched);
+
+/* a few global variables */
+
+static char *szProgName = PROGNAME;
+static char *szAppName = LONGNAME;
+static char *szIconName = PROGNAME;
+static char szCmdFileName [MAX_PATH];
+
+/* MAIN routine */
+
+int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
+ PSTR szCmdLine, int iCmdShow)
+{
+ HACCEL hAccel;
+ HWND hwnd;
+ MSG msg;
+ WNDCLASS wndclass;
+ int ixBorders, iyBorders;
+
+ wndclass.style = CS_HREDRAW | CS_VREDRAW;
+ wndclass.lpfnWndProc = WndProc;
+ wndclass.cbClsExtra = 0;
+ wndclass.cbWndExtra = 0;
+ wndclass.hInstance = hInstance;
+ wndclass.hIcon = LoadIcon (hInstance, szIconName) ;
+ wndclass.hCursor = LoadCursor (NULL, IDC_ARROW);
+ wndclass.hbrBackground = NULL; /* (HBRUSH) GetStockObject (GRAY_BRUSH); */
+ wndclass.lpszMenuName = szProgName;
+ wndclass.lpszClassName = szProgName;
+
+ if (!RegisterClass (&wndclass))
+ {
+ MessageBox (NULL, TEXT ("Error: this program requires Windows NT!"),
+ szProgName, MB_ICONERROR);
+ return 0;
+ }
+
+ /* if filename given on commandline, store it */
+ if ((szCmdLine != NULL) && (*szCmdLine != '\0'))
+ if (szCmdLine[0] == '"')
+ strncpy (szCmdFileName, szCmdLine + 1, strlen(szCmdLine) - 2);
+ else
+ strcpy (szCmdFileName, szCmdLine);
+ else
+ strcpy (szCmdFileName, "");
+
+ /* calculate size of window-borders */
+ ixBorders = 2 * (GetSystemMetrics (SM_CXBORDER) +
+ GetSystemMetrics (SM_CXDLGFRAME));
+ iyBorders = 2 * (GetSystemMetrics (SM_CYBORDER) +
+ GetSystemMetrics (SM_CYDLGFRAME)) +
+ GetSystemMetrics (SM_CYCAPTION) +
+ GetSystemMetrics (SM_CYMENUSIZE) +
+ 1; /* WvS: don't ask me why? */
+
+ hwnd = CreateWindow (szProgName, szAppName,
+ WS_OVERLAPPEDWINDOW,
+ CW_USEDEFAULT, CW_USEDEFAULT,
+ 512 + 2 * MARGIN + ixBorders, 384 + 2 * MARGIN + iyBorders,
+/* CW_USEDEFAULT, CW_USEDEFAULT, */
+ NULL, NULL, hInstance, NULL);
+
+ ShowWindow (hwnd, iCmdShow);
+ UpdateWindow (hwnd);
+
+ hAccel = LoadAccelerators (hInstance, szProgName);
+
+ while (GetMessage (&msg, NULL, 0, 0))
+ {
+ if (!TranslateAccelerator (hwnd, hAccel, &msg))
+ {
+ TranslateMessage (&msg);
+ DispatchMessage (&msg);
+ }
+ }
+ return msg.wParam;
+}
+
+LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam,
+ LPARAM lParam)
+{
+ static HINSTANCE hInstance ;
+ static HDC hdc;
+ static PAINTSTRUCT ps;
+ static HMENU hMenu;
+
+ static BITMAPFILEHEADER *pbmfh;
+ static BITMAPINFOHEADER *pbmih;
+ static BYTE *pbImage;
+ static int cxWinSize, cyWinSize;
+ static int cxImgSize, cyImgSize;
+ static int cImgChannels;
+ static png_color bkgColor = {127, 127, 127};
+
+ static BOOL bStretched = TRUE;
+
+ static BYTE *pDib = NULL;
+ static BYTE *pDiData = NULL;
+
+ static TCHAR szImgPathName [MAX_PATH];
+ static TCHAR szTitleName [MAX_PATH];
+
+ static TCHAR *pPngFileList = NULL;
+ static int iPngFileCount;
+ static int iPngFileIndex;
+
+ BOOL bOk;
+
+ switch (message)
+ {
+ case WM_CREATE:
+ hInstance = ((LPCREATESTRUCT) lParam)->hInstance ;
+ PngFileInitialize (hwnd);
+
+ strcpy (szImgPathName, "");
+
+ /* in case we process file given on command-line */
+
+ if (szCmdFileName[0] != '\0')
+ {
+ strcpy (szImgPathName, szCmdFileName);
+
+ /* read the other png-files in the directory for later */
+ /* next/previous commands */
+
+ BuildPngList (szImgPathName, &pPngFileList, &iPngFileCount,
+ &iPngFileIndex);
+
+ /* load the image from file */
+
+ if (!LoadImageFile (hwnd, szImgPathName,
+ &pbImage, &cxImgSize, &cyImgSize, &cImgChannels, &bkgColor))
+ return 0;
+
+ /* invalidate the client area for later update */
+
+ InvalidateRect (hwnd, NULL, TRUE);
+
+ /* display the PNG into the DIBitmap */
+
+ DisplayImage (hwnd, &pDib, &pDiData, cxWinSize, cyWinSize,
+ pbImage, cxImgSize, cyImgSize, cImgChannels, bStretched);
+ }
+
+ return 0;
+
+ case WM_SIZE:
+ cxWinSize = LOWORD (lParam);
+ cyWinSize = HIWORD (lParam);
+
+ /* invalidate the client area for later update */
+
+ InvalidateRect (hwnd, NULL, TRUE);
+
+ /* display the PNG into the DIBitmap */
+
+ DisplayImage (hwnd, &pDib, &pDiData, cxWinSize, cyWinSize,
+ pbImage, cxImgSize, cyImgSize, cImgChannels, bStretched);
+
+ return 0;
+
+ case WM_INITMENUPOPUP:
+ hMenu = GetMenu (hwnd);
+
+ if (pbImage)
+ EnableMenuItem (hMenu, IDM_FILE_SAVE, MF_ENABLED);
+ else
+ EnableMenuItem (hMenu, IDM_FILE_SAVE, MF_GRAYED);
+
+ return 0;
+
+ case WM_COMMAND:
+ hMenu = GetMenu (hwnd);
+
+ switch (LOWORD (wParam))
+ {
+ case IDM_FILE_OPEN:
+
+ /* show the File Open dialog box */
+
+ if (!PngFileOpenDlg (hwnd, szImgPathName, szTitleName))
+ return 0;
+
+ /* read the other png-files in the directory for later */
+ /* next/previous commands */
+
+ BuildPngList (szImgPathName, &pPngFileList, &iPngFileCount,
+ &iPngFileIndex);
+
+ /* load the image from file */
+
+ if (!LoadImageFile (hwnd, szImgPathName,
+ &pbImage, &cxImgSize, &cyImgSize, &cImgChannels, &bkgColor))
+ return 0;
+
+ /* invalidate the client area for later update */
+
+ InvalidateRect (hwnd, NULL, TRUE);
+
+ /* display the PNG into the DIBitmap */
+
+ DisplayImage (hwnd, &pDib, &pDiData, cxWinSize, cyWinSize,
+ pbImage, cxImgSize, cyImgSize, cImgChannels, bStretched);
+
+ return 0;
+
+ case IDM_FILE_SAVE:
+
+ /* show the File Save dialog box */
+
+ if (!PngFileSaveDlg (hwnd, szImgPathName, szTitleName))
+ return 0;
+
+ /* save the PNG to a disk file */
+
+ SetCursor (LoadCursor (NULL, IDC_WAIT));
+ ShowCursor (TRUE);
+
+ bOk = PngSaveImage (szImgPathName, pDiData, cxWinSize, cyWinSize,
+ bkgColor);
+
+ ShowCursor (FALSE);
+ SetCursor (LoadCursor (NULL, IDC_ARROW));
+
+ if (!bOk)
+ MessageBox (hwnd, TEXT ("Error in saving the PNG image"),
+ szProgName, MB_ICONEXCLAMATION | MB_OK);
+ return 0;
+
+ case IDM_FILE_NEXT:
+
+ /* read next entry in the directory */
+
+ if (SearchPngList (pPngFileList, iPngFileCount, &iPngFileIndex,
+ NULL, szImgPathName))
+ {
+ if (strcmp (szImgPathName, "") == 0)
+ return 0;
+
+ /* load the image from file */
+
+ if (!LoadImageFile (hwnd, szImgPathName, &pbImage,
+ &cxImgSize, &cyImgSize, &cImgChannels, &bkgColor))
+ return 0;
+
+ /* invalidate the client area for later update */
+
+ InvalidateRect (hwnd, NULL, TRUE);
+
+ /* display the PNG into the DIBitmap */
+
+ DisplayImage (hwnd, &pDib, &pDiData, cxWinSize, cyWinSize,
+ pbImage, cxImgSize, cyImgSize, cImgChannels, bStretched);
+ }
+
+ return 0;
+
+ case IDM_FILE_PREVIOUS:
+
+ /* read previous entry in the directory */
+
+ if (SearchPngList (pPngFileList, iPngFileCount, &iPngFileIndex,
+ szImgPathName, NULL))
+ {
+
+ if (strcmp (szImgPathName, "") == 0)
+ return 0;
+
+ /* load the image from file */
+
+ if (!LoadImageFile (hwnd, szImgPathName, &pbImage, &cxImgSize,
+ &cyImgSize, &cImgChannels, &bkgColor))
+ return 0;
+
+ /* invalidate the client area for later update */
+
+ InvalidateRect (hwnd, NULL, TRUE);
+
+ /* display the PNG into the DIBitmap */
+
+ DisplayImage (hwnd, &pDib, &pDiData, cxWinSize, cyWinSize,
+ pbImage, cxImgSize, cyImgSize, cImgChannels, bStretched);
+ }
+
+ return 0;
+
+ case IDM_FILE_EXIT:
+
+ /* more cleanup needed... */
+
+ /* free image buffer */
+
+ if (pDib != NULL)
+ {
+ free (pDib);
+ pDib = NULL;
+ }
+
+ /* free file-list */
+
+ if (pPngFileList != NULL)
+ {
+ free (pPngFileList);
+ pPngFileList = NULL;
+ }
+
+ /* let's go ... */
+
+ exit (0);
+
+ return 0;
+
+ case IDM_OPTIONS_STRETCH:
+ bStretched = !bStretched;
+ if (bStretched)
+ CheckMenuItem (hMenu, IDM_OPTIONS_STRETCH, MF_CHECKED);
+ else
+ CheckMenuItem (hMenu, IDM_OPTIONS_STRETCH, MF_UNCHECKED);
+
+ /* invalidate the client area for later update */
+
+ InvalidateRect (hwnd, NULL, TRUE);
+
+ /* display the PNG into the DIBitmap */
+
+ DisplayImage (hwnd, &pDib, &pDiData, cxWinSize, cyWinSize,
+ pbImage, cxImgSize, cyImgSize, cImgChannels, bStretched);
+
+ return 0;
+
+ case IDM_HELP_ABOUT:
+ DialogBox (hInstance, TEXT ("AboutBox"), hwnd, AboutDlgProc) ;
+ return 0;
+
+ } /* end switch */
+
+ break;
+
+ case WM_PAINT:
+ hdc = BeginPaint (hwnd, &ps);
+
+ if (pDib)
+ SetDIBitsToDevice (hdc, 0, 0, cxWinSize, cyWinSize, 0, 0,
+ 0, cyWinSize, pDiData, (BITMAPINFO *) pDib, DIB_RGB_COLORS);
+
+ EndPaint (hwnd, &ps);
+ return 0;
+
+ case WM_DESTROY:
+ if (pbmfh)
+ {
+ free (pbmfh);
+ pbmfh = NULL;
+ }
+
+ PostQuitMessage (0);
+ return 0;
+ }
+
+ return DefWindowProc (hwnd, message, wParam, lParam);
+}
+
+BOOL CALLBACK AboutDlgProc (HWND hDlg, UINT message,
+ WPARAM wParam, LPARAM lParam)
+{
+ switch (message)
+ {
+ case WM_INITDIALOG :
+ ShowWindow (hDlg, SW_HIDE);
+ CenterAbout (hDlg, GetWindow (hDlg, GW_OWNER));
+ ShowWindow (hDlg, SW_SHOW);
+ return TRUE ;
+
+ case WM_COMMAND :
+ switch (LOWORD (wParam))
+ {
+ case IDOK :
+ case IDCANCEL :
+ EndDialog (hDlg, 0) ;
+ return TRUE ;
+ }
+ break ;
+ }
+ return FALSE ;
+}
+
+/*---------------
+ * CenterAbout
+ *---------------
+ */
+BOOL CenterAbout (HWND hwndChild, HWND hwndParent)
+{
+ RECT rChild, rParent, rWorkArea;
+ int wChild, hChild, wParent, hParent;
+ int xNew, yNew;
+ BOOL bResult;
+
+ /* Get the Height and Width of the child window */
+ GetWindowRect (hwndChild, &rChild);
+ wChild = rChild.right - rChild.left;
+ hChild = rChild.bottom - rChild.top;
+
+ /* Get the Height and Width of the parent window */
+ GetWindowRect (hwndParent, &rParent);
+ wParent = rParent.right - rParent.left;
+ hParent = rParent.bottom - rParent.top;
+
+ /* Get the limits of the 'workarea' */
+ bResult = SystemParametersInfo(
+ SPI_GETWORKAREA, /* system parameter to query or set */
+ sizeof(RECT),
+ &rWorkArea,
+ 0);
+ if (!bResult) {
+ rWorkArea.left = rWorkArea.top = 0;
+ rWorkArea.right = GetSystemMetrics(SM_CXSCREEN);
+ rWorkArea.bottom = GetSystemMetrics(SM_CYSCREEN);
+ }
+
+ /* Calculate new X position, then adjust for workarea */
+ xNew = rParent.left + ((wParent - wChild) /2);
+ if (xNew < rWorkArea.left) {
+ xNew = rWorkArea.left;
+ } else if ((xNew+wChild) > rWorkArea.right) {
+ xNew = rWorkArea.right - wChild;
+ }
+
+ /* Calculate new Y position, then adjust for workarea */
+ yNew = rParent.top + ((hParent - hChild) /2);
+ if (yNew < rWorkArea.top) {
+ yNew = rWorkArea.top;
+ } else if ((yNew+hChild) > rWorkArea.bottom) {
+ yNew = rWorkArea.bottom - hChild;
+ }
+
+ /* Set it, and return */
+ return SetWindowPos (hwndChild, NULL, xNew, yNew, 0, 0, SWP_NOSIZE |
+ SWP_NOZORDER);
+}
+
+/*----------------
+ * BuildPngList
+ *----------------
+ */
+BOOL BuildPngList (PTSTR pstrPathName, TCHAR **ppFileList, int *pFileCount,
+ int *pFileIndex)
+{
+ static TCHAR szImgPathName [MAX_PATH];
+ static TCHAR szImgFileName [MAX_PATH];
+ static TCHAR szImgFindName [MAX_PATH];
+
+ WIN32_FIND_DATA finddata;
+ HANDLE hFind;
+
+ static TCHAR szTmp [MAX_PATH];
+ BOOL bOk;
+ int i, ii;
+ int j, jj;
+
+ /* free previous file-list */
+
+ if (*ppFileList != NULL)
+ {
+ free (*ppFileList);
+ *ppFileList = NULL;
+ }
+
+ /* extract foldername, filename and search-name */
+
+ strcpy (szImgPathName, pstrPathName);
+ strcpy (szImgFileName, strrchr (pstrPathName, '\\') + 1);
+
+ strcpy (szImgFindName, szImgPathName);
+ *(strrchr (szImgFindName, '\\') + 1) = '\0';
+ strcat (szImgFindName, "*.png");
+
+ /* first cycle: count number of files in directory for memory allocation */
+
+ *pFileCount = 0;
+
+ hFind = FindFirstFile(szImgFindName, &finddata);
+ bOk = (hFind != (HANDLE) -1);
+
+ while (bOk)
+ {
+ *pFileCount += 1;
+ bOk = FindNextFile(hFind, &finddata);
+ }
+ FindClose(hFind);
+
+ /* allocation memory for file-list */
+
+ *ppFileList = (TCHAR *) malloc (*pFileCount * MAX_PATH);
+
+ /* second cycle: read directory and store filenames in file-list */
+
+ hFind = FindFirstFile(szImgFindName, &finddata);
+ bOk = (hFind != (HANDLE) -1);
+
+ i = 0;
+ ii = 0;
+ while (bOk)
+ {
+ strcpy (*ppFileList + ii, szImgPathName);
+ strcpy (strrchr(*ppFileList + ii, '\\') + 1, finddata.cFileName);
+
+ if (strcmp(pstrPathName, *ppFileList + ii) == 0)
+ *pFileIndex = i;
+
+ ii += MAX_PATH;
+ i++;
+
+ bOk = FindNextFile(hFind, &finddata);
+ }
+ FindClose(hFind);
+
+ /* finally we must sort the file-list */
+
+ for (i = 0; i < *pFileCount - 1; i++)
+ {
+ ii = i * MAX_PATH;
+ for (j = i+1; j < *pFileCount; j++)
+ {
+ jj = j * MAX_PATH;
+ if (strcmp (*ppFileList + ii, *ppFileList + jj) > 0)
+ {
+ strcpy (szTmp, *ppFileList + jj);
+ strcpy (*ppFileList + jj, *ppFileList + ii);
+ strcpy (*ppFileList + ii, szTmp);
+
+ /* check if this was the current image that we moved */
+
+ if (*pFileIndex == i)
+ *pFileIndex = j;
+ else
+ if (*pFileIndex == j)
+ *pFileIndex = i;
+ }
+ }
+ }
+
+ return TRUE;
+}
+
+/*----------------
+ * SearchPngList
+ *----------------
+ */
+
+BOOL SearchPngList (
+ TCHAR *pFileList, int FileCount, int *pFileIndex,
+ PTSTR pstrPrevName, PTSTR pstrNextName)
+{
+ if (FileCount > 0)
+ {
+ /* get previous entry */
+
+ if (pstrPrevName != NULL)
+ {
+ if (*pFileIndex > 0)
+ *pFileIndex -= 1;
+ else
+ *pFileIndex = FileCount - 1;
+
+ strcpy (pstrPrevName, pFileList + (*pFileIndex * MAX_PATH));
+ }
+
+ /* get next entry */
+
+ if (pstrNextName != NULL)
+ {
+ if (*pFileIndex < FileCount - 1)
+ *pFileIndex += 1;
+ else
+ *pFileIndex = 0;
+
+ strcpy (pstrNextName, pFileList + (*pFileIndex * MAX_PATH));
+ }
+
+ return TRUE;
+ }
+ else
+ {
+ return FALSE;
+ }
+}
+
+/*-----------------
+ * LoadImageFile
+ *-----------------
+ */
+
+BOOL LoadImageFile (HWND hwnd, PTSTR pstrPathName,
+ png_byte **ppbImage, int *pxImgSize, int *pyImgSize,
+ int *piChannels, png_color *pBkgColor)
+{
+ static TCHAR szTmp [MAX_PATH];
+
+ /* if there's an existing PNG, free the memory */
+
+ if (*ppbImage)
+ {
+ free (*ppbImage);
+ *ppbImage = NULL;
+ }
+
+ /* Load the entire PNG into memory */
+
+ SetCursor (LoadCursor (NULL, IDC_WAIT));
+ ShowCursor (TRUE);
+
+ PngLoadImage (pstrPathName, ppbImage, pxImgSize, pyImgSize, piChannels,
+ pBkgColor);
+
+ ShowCursor (FALSE);
+ SetCursor (LoadCursor (NULL, IDC_ARROW));
+
+ if (*ppbImage != NULL)
+ {
+ sprintf (szTmp, "VisualPng - %s", strrchr(pstrPathName, '\\') + 1);
+ SetWindowText (hwnd, szTmp);
+ }
+ else
+ {
+ MessageBox (hwnd, TEXT ("Error in loading the PNG image"),
+ szProgName, MB_ICONEXCLAMATION | MB_OK);
+ return FALSE;
+ }
+
+ return TRUE;
+}
+
+/*----------------
+ * DisplayImage
+ *----------------
+ */
+BOOL DisplayImage (HWND hwnd, BYTE **ppDib,
+ BYTE **ppDiData, int cxWinSize, int cyWinSize,
+ BYTE *pbImage, int cxImgSize, int cyImgSize, int cImgChannels,
+ BOOL bStretched)
+{
+ BYTE *pDib = *ppDib;
+ BYTE *pDiData = *ppDiData;
+ /* BITMAPFILEHEADER *pbmfh; */
+ BITMAPINFOHEADER *pbmih;
+ WORD wDIRowBytes;
+ png_color bkgBlack = {0, 0, 0};
+ png_color bkgGray = {127, 127, 127};
+ png_color bkgWhite = {255, 255, 255};
+
+ /* allocate memory for the Device Independant bitmap */
+
+ wDIRowBytes = (WORD) ((3 * cxWinSize + 3L) >> 2) << 2;
+
+ if (pDib)
+ {
+ free (pDib);
+ pDib = NULL;
+ }
+
+ if (!(pDib = (BYTE *) malloc (sizeof(BITMAPINFOHEADER) +
+ wDIRowBytes * cyWinSize)))
+ {
+ MessageBox (hwnd, TEXT ("Error in displaying the PNG image"),
+ szProgName, MB_ICONEXCLAMATION | MB_OK);
+ *ppDib = pDib = NULL;
+ return FALSE;
+ }
+ *ppDib = pDib;
+ memset (pDib, 0, sizeof(BITMAPINFOHEADER));
+
+ /* initialize the dib-structure */
+
+ pbmih = (BITMAPINFOHEADER *) pDib;
+ pbmih->biSize = sizeof(BITMAPINFOHEADER);
+ pbmih->biWidth = cxWinSize;
+ pbmih->biHeight = -((long) cyWinSize);
+ pbmih->biPlanes = 1;
+ pbmih->biBitCount = 24;
+ pbmih->biCompression = 0;
+ pDiData = pDib + sizeof(BITMAPINFOHEADER);
+ *ppDiData = pDiData;
+
+ /* first fill bitmap with gray and image border */
+
+ InitBitmap (pDiData, cxWinSize, cyWinSize);
+
+ /* then fill bitmap with image */
+
+ if (pbImage)
+ {
+ FillBitmap (
+ pDiData, cxWinSize, cyWinSize,
+ pbImage, cxImgSize, cyImgSize, cImgChannels,
+ bStretched);
+ }
+
+ return TRUE;
+}
+
+/*--------------
+ * InitBitmap
+ *--------------
+ */
+BOOL InitBitmap (BYTE *pDiData, int cxWinSize, int cyWinSize)
+{
+ BYTE *dst;
+ int x, y, col;
+
+ /* initialize the background with gray */
+
+ dst = pDiData;
+ for (y = 0; y < cyWinSize; y++)
+ {
+ col = 0;
+ for (x = 0; x < cxWinSize; x++)
+ {
+ /* fill with GRAY */
+ *dst++ = 127;
+ *dst++ = 127;
+ *dst++ = 127;
+ col += 3;
+ }
+ /* rows start on 4 byte boundaries */
+ while ((col % 4) != 0)
+ {
+ dst++;
+ col++;
+ }
+ }
+
+ return TRUE;
+}
+
+/*--------------
+ * FillBitmap
+ *--------------
+ */
+BOOL FillBitmap (
+ BYTE *pDiData, int cxWinSize, int cyWinSize,
+ BYTE *pbImage, int cxImgSize, int cyImgSize, int cImgChannels,
+ BOOL bStretched)
+{
+ BYTE *pStretchedImage;
+ BYTE *pImg;
+ BYTE *src, *dst;
+ BYTE r, g, b, a;
+ const int cDIChannels = 3;
+ WORD wImgRowBytes;
+ WORD wDIRowBytes;
+ int cxNewSize, cyNewSize;
+ int cxImgPos, cyImgPos;
+ int xImg, yImg;
+ int xWin, yWin;
+ int xOld, yOld;
+ int xNew, yNew;
+
+ if (bStretched)
+ {
+ cxNewSize = cxWinSize - 2 * MARGIN;
+ cyNewSize = cyWinSize - 2 * MARGIN;
+
+ /* stretch the image to it's window determined size */
+
+ /* the following two are mathematically the same, but the first
+ * has side-effects because of rounding
+ */
+/* if ((cyNewSize / cxNewSize) > (cyImgSize / cxImgSize)) */
+ if ((cyNewSize * cxImgSize) > (cyImgSize * cxNewSize))
+ {
+ cyNewSize = cxNewSize * cyImgSize / cxImgSize;
+ cxImgPos = MARGIN;
+ cyImgPos = (cyWinSize - cyNewSize) / 2;
+ }
+ else
+ {
+ cxNewSize = cyNewSize * cxImgSize / cyImgSize;
+ cyImgPos = MARGIN;
+ cxImgPos = (cxWinSize - cxNewSize) / 2;
+ }
+
+ pStretchedImage = malloc (cImgChannels * cxNewSize * cyNewSize);
+ pImg = pStretchedImage;
+
+ for (yNew = 0; yNew < cyNewSize; yNew++)
+ {
+ yOld = yNew * cyImgSize / cyNewSize;
+ for (xNew = 0; xNew < cxNewSize; xNew++)
+ {
+ xOld = xNew * cxImgSize / cxNewSize;
+
+ r = *(pbImage + cImgChannels * ((yOld * cxImgSize) + xOld) + 0);
+ g = *(pbImage + cImgChannels * ((yOld * cxImgSize) + xOld) + 1);
+ b = *(pbImage + cImgChannels * ((yOld * cxImgSize) + xOld) + 2);
+ *pImg++ = r;
+ *pImg++ = g;
+ *pImg++ = b;
+ if (cImgChannels == 4)
+ {
+ a = *(pbImage + cImgChannels * ((yOld * cxImgSize) + xOld)
+ + 3);
+ *pImg++ = a;
+ }
+ }
+ }
+
+ /* calculate row-bytes */
+
+ wImgRowBytes = cImgChannels * cxNewSize;
+ wDIRowBytes = (WORD) ((cDIChannels * cxWinSize + 3L) >> 2) << 2;
+
+ /* copy image to screen */
+
+ for (yImg = 0, yWin = cyImgPos; yImg < cyNewSize; yImg++, yWin++)
+ {
+ if (yWin >= cyWinSize - cyImgPos)
+ break;
+ src = pStretchedImage + yImg * wImgRowBytes;
+ dst = pDiData + yWin * wDIRowBytes + cxImgPos * cDIChannels;
+
+ for (xImg = 0, xWin = cxImgPos; xImg < cxNewSize; xImg++, xWin++)
+ {
+ if (xWin >= cxWinSize - cxImgPos)
+ break;
+ r = *src++;
+ g = *src++;
+ b = *src++;
+ *dst++ = b; /* note the reverse order */
+ *dst++ = g;
+ *dst++ = r;
+ if (cImgChannels == 4)
+ {
+ a = *src++;
+ }
+ }
+ }
+
+ /* free memory */
+
+ if (pStretchedImage != NULL)
+ {
+ free (pStretchedImage);
+ pStretchedImage = NULL;
+ }
+
+ }
+
+ /* process the image not-stretched */
+
+ else
+ {
+ /* calculate the central position */
+
+ cxImgPos = (cxWinSize - cxImgSize) / 2;
+ cyImgPos = (cyWinSize - cyImgSize) / 2;
+
+ /* check for image larger than window */
+
+ if (cxImgPos < MARGIN)
+ cxImgPos = MARGIN;
+ if (cyImgPos < MARGIN)
+ cyImgPos = MARGIN;
+
+ /* calculate both row-bytes */
+
+ wImgRowBytes = cImgChannels * cxImgSize;
+ wDIRowBytes = (WORD) ((cDIChannels * cxWinSize + 3L) >> 2) << 2;
+
+ /* copy image to screen */
+
+ for (yImg = 0, yWin = cyImgPos; yImg < cyImgSize; yImg++, yWin++)
+ {
+ if (yWin >= cyWinSize - MARGIN)
+ break;
+ src = pbImage + yImg * wImgRowBytes;
+ dst = pDiData + yWin * wDIRowBytes + cxImgPos * cDIChannels;
+
+ for (xImg = 0, xWin = cxImgPos; xImg < cxImgSize; xImg++, xWin++)
+ {
+ if (xWin >= cxWinSize - MARGIN)
+ break;
+ r = *src++;
+ g = *src++;
+ b = *src++;
+ *dst++ = b; /* note the reverse order */
+ *dst++ = g;
+ *dst++ = r;
+ if (cImgChannels == 4)
+ {
+ a = *src++;
+ }
+ }
+ }
+ }
+
+ return TRUE;
+}
+
+/*-----------------
+ * end of source
+ *-----------------
+ */
diff --git a/libpng/contrib/visupng/VisualPng.dsp b/libpng/contrib/visupng/VisualPng.dsp
new file mode 100644
index 0000000..741ef6c
--- /dev/null
+++ b/libpng/contrib/visupng/VisualPng.dsp
@@ -0,0 +1,147 @@
+# Microsoft Developer Studio Project File - Name="VisualPng" - Package Owner=<4>
+# Microsoft Developer Studio Generated Build File, Format Version 6.00
+# ** DO NOT EDIT **
+
+# TARGTYPE "Win32 (x86) Application" 0x0101
+
+CFG=VisualPng - Win32 Debug
+!MESSAGE This is not a valid makefile. To build this project using NMAKE,
+!MESSAGE use the Export Makefile command and run
+!MESSAGE
+!MESSAGE NMAKE /f "VisualPng.mak".
+!MESSAGE
+!MESSAGE You can specify a configuration when running NMAKE
+!MESSAGE by defining the macro CFG on the command line. For example:
+!MESSAGE
+!MESSAGE NMAKE /f "VisualPng.mak" CFG="VisualPng - Win32 Debug"
+!MESSAGE
+!MESSAGE Possible choices for configuration are:
+!MESSAGE
+!MESSAGE "VisualPng - Win32 Release" (based on "Win32 (x86) Application")
+!MESSAGE "VisualPng - Win32 Debug" (based on "Win32 (x86) Application")
+!MESSAGE
+
+# Begin Project
+# PROP AllowPerConfigDependencies 0
+# PROP Scc_ProjName ""
+# PROP Scc_LocalPath ""
+CPP=cl.exe
+MTL=midl.exe
+RSC=rc.exe
+
+!IF "$(CFG)" == "VisualPng - Win32 Release"
+
+# PROP BASE Use_MFC 0
+# PROP BASE Use_Debug_Libraries 0
+# PROP BASE Output_Dir "Release"
+# PROP BASE Intermediate_Dir "Release"
+# PROP BASE Ignore_Export_Lib 0
+# PROP BASE Target_Dir ""
+# PROP Use_MFC 0
+# PROP Use_Debug_Libraries 0
+# PROP Output_Dir "Release"
+# PROP Intermediate_Dir "Release"
+# PROP Ignore_Export_Lib 0
+# PROP Target_Dir ""
+# ADD BASE CPP /nologo /W3 /O2 /I "..\.." /I "..\..\..\zlib" /D "WIN32" /D "NDEBUG" /D "PNG_NO_STDIO" /FD /c
+# SUBTRACT BASE CPP /YX
+# ADD CPP /nologo /MD /W3 /O2 /I "..\.." /I "..\..\..\zlib" /D "WIN32" /D "NDEBUG" /D "PNG_NO_STDIO" /FD /c
+# SUBTRACT CPP /YX
+# ADD BASE MTL /nologo /D "NDEBUG" /mktyplib203 /win32
+# ADD MTL /nologo /D "NDEBUG" /mktyplib203 /win32
+# ADD BASE RSC /l 0x409 /d "NDEBUG"
+# ADD RSC /l 0x409 /d "NDEBUG"
+BSC32=bscmake.exe
+# ADD BASE BSC32 /nologo
+# ADD BSC32 /nologo
+LINK32=link.exe
+# ADD BASE LINK32 kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib /nologo /subsystem:windows /machine:I386
+# ADD LINK32 ..\..\projects\visualc6\Win32_LIB_Release\libpng.lib ..\..\..\zlib\projects\visualc6\Win32_LIB_Release\zlib.lib kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib /nologo /subsystem:windows /machine:I386
+# Begin Special Build Tool
+OutDir=.\Release
+SOURCE="$(InputPath)"
+PostBuild_Cmds=$(outdir)\VisualPng.exe ..\..\contrib\pngsuite\basn6a16.png
+# End Special Build Tool
+
+!ELSEIF "$(CFG)" == "VisualPng - Win32 Debug"
+
+# PROP BASE Use_MFC 0
+# PROP BASE Use_Debug_Libraries 1
+# PROP BASE Output_Dir "Debug"
+# PROP BASE Intermediate_Dir "Debug"
+# PROP BASE Ignore_Export_Lib 0
+# PROP BASE Target_Dir ""
+# PROP Use_MFC 0
+# PROP Use_Debug_Libraries 1
+# PROP Output_Dir "Debug"
+# PROP Intermediate_Dir "Debug"
+# PROP Ignore_Export_Lib 0
+# PROP Target_Dir ""
+# ADD BASE CPP /nologo /W3 /Gm /ZI /Od /I "..\.." /I "..\..\..\zlib" /D "WIN32" /D "_DEBUG" /D "PNG_NO_STDIO" /FD /GZ /c
+# SUBTRACT BASE CPP /YX
+# ADD CPP /nologo /MDd /W3 /Gm /ZI /Od /I "..\.." /I "..\..\..\zlib" /D "WIN32" /D "_DEBUG" /D "PNG_NO_STDIO" /FD /GZ /c
+# SUBTRACT CPP /YX
+# ADD BASE MTL /nologo /D "_DEBUG" /mktyplib203 /win32
+# ADD MTL /nologo /D "_DEBUG" /mktyplib203 /win32
+# ADD BASE RSC /l 0x409 /d "_DEBUG"
+# ADD RSC /l 0x409 /d "_DEBUG"
+BSC32=bscmake.exe
+# ADD BASE BSC32 /nologo
+# ADD BSC32 /nologo
+LINK32=link.exe
+# ADD BASE LINK32 kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib /nologo /subsystem:windows /debug /machine:I386 /pdbtype:sept
+# ADD LINK32 ..\..\projects\visualc6\Win32_LIB_Release\libpng.lib ..\..\..\zlib\projects\visualc6\Win32_LIB_Release\zlib.lib kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib /nologo /subsystem:windows /debug /machine:I386 /nodefaultlib:"msvcrt.lib" /pdbtype:sept
+# Begin Special Build Tool
+OutDir=.\Debug
+SOURCE="$(InputPath)"
+PostBuild_Cmds=$(outdir)\VisualPng.exe ..\..\contrib\pngsuite\basn6a16.png
+# End Special Build Tool
+
+!ENDIF
+
+# Begin Target
+
+# Name "VisualPng - Win32 Release"
+# Name "VisualPng - Win32 Debug"
+# Begin Group "Source Files"
+
+# PROP Default_Filter "cpp;c;cxx;rc;def;r;odl;idl;hpj;bat"
+# Begin Source File
+
+SOURCE=.\PngFile.c
+# End Source File
+# Begin Source File
+
+SOURCE=.\VisualPng.c
+# End Source File
+# End Group
+# Begin Group "Header Files"
+
+# PROP Default_Filter "h;hpp;hxx;hm;inl"
+# Begin Source File
+
+SOURCE=.\cexcept.h
+# End Source File
+# Begin Source File
+
+SOURCE=.\PngFile.h
+# End Source File
+# Begin Source File
+
+SOURCE=.\resource.h
+# End Source File
+# End Group
+# Begin Group "Resource Files"
+
+# PROP Default_Filter "ico;cur;bmp;dlg;rc2;rct;bin;rgs;gif;jpg;jpeg;jpe"
+# Begin Source File
+
+SOURCE=.\VisualPng.ico
+# End Source File
+# Begin Source File
+
+SOURCE=.\VisualPng.rc
+# End Source File
+# End Group
+# End Target
+# End Project
diff --git a/libpng/contrib/visupng/VisualPng.dsw b/libpng/contrib/visupng/VisualPng.dsw
new file mode 100644
index 0000000..a30e1cc
--- /dev/null
+++ b/libpng/contrib/visupng/VisualPng.dsw
@@ -0,0 +1,29 @@
+Microsoft Developer Studio Workspace File, Format Version 6.00
+# WARNING: DO NOT EDIT OR DELETE THIS WORKSPACE FILE!
+
+###############################################################################
+
+Project: "VisualPng"=.\VisualPng.dsp - Package Owner=<4>
+
+Package=<5>
+{{{
+}}}
+
+Package=<4>
+{{{
+}}}
+
+###############################################################################
+
+Global:
+
+Package=<5>
+{{{
+}}}
+
+Package=<3>
+{{{
+}}}
+
+###############################################################################
+
diff --git a/libpng/contrib/visupng/VisualPng.ico b/libpng/contrib/visupng/VisualPng.ico
new file mode 100644
index 0000000..68aa371
--- /dev/null
+++ b/libpng/contrib/visupng/VisualPng.ico
Binary files differ
diff --git a/libpng/contrib/visupng/VisualPng.png b/libpng/contrib/visupng/VisualPng.png
new file mode 100644
index 0000000..c6aa80a
--- /dev/null
+++ b/libpng/contrib/visupng/VisualPng.png
Binary files differ
diff --git a/libpng/contrib/visupng/VisualPng.rc b/libpng/contrib/visupng/VisualPng.rc
new file mode 100644
index 0000000..6e0623a
--- /dev/null
+++ b/libpng/contrib/visupng/VisualPng.rc
@@ -0,0 +1,152 @@
+//Microsoft Developer Studio generated resource script.
+//
+#include "resource.h"
+
+#define APSTUDIO_READONLY_SYMBOLS
+/////////////////////////////////////////////////////////////////////////////
+//
+// Generated from the TEXTINCLUDE 2 resource.
+//
+#include "afxres.h"
+
+/////////////////////////////////////////////////////////////////////////////
+#undef APSTUDIO_READONLY_SYMBOLS
+
+/////////////////////////////////////////////////////////////////////////////
+// English (U.S.) resources
+
+#if !defined(AFX_RESOURCE_DLL) || defined(AFX_TARG_ENU)
+#ifdef _WIN32
+LANGUAGE LANG_ENGLISH, SUBLANG_ENGLISH_US
+#pragma code_page(1252)
+#endif //_WIN32
+
+#ifdef APSTUDIO_INVOKED
+/////////////////////////////////////////////////////////////////////////////
+//
+// TEXTINCLUDE
+//
+
+1 TEXTINCLUDE DISCARDABLE
+BEGIN
+ "resource.h\0"
+END
+
+2 TEXTINCLUDE DISCARDABLE
+BEGIN
+ "#include ""afxres.h""\r\n"
+ "\0"
+END
+
+3 TEXTINCLUDE DISCARDABLE
+BEGIN
+ "\r\n"
+ "\0"
+END
+
+#endif // APSTUDIO_INVOKED
+
+
+/////////////////////////////////////////////////////////////////////////////
+//
+// Menu
+//
+
+VISUALPNG MENU DISCARDABLE
+BEGIN
+ POPUP "&File"
+ BEGIN
+ MENUITEM "&Open Image...\tCtrl+O", IDM_FILE_OPEN
+ MENUITEM "Save &As...", IDM_FILE_SAVE
+ MENUITEM SEPARATOR
+ MENUITEM "&Next Image\tCtrl+N", IDM_FILE_NEXT
+ MENUITEM "Pre&vious Image\tCtrl+V", IDM_FILE_PREVIOUS
+ MENUITEM SEPARATOR
+ MENUITEM "E&xit\tAlt+X", IDM_FILE_EXIT
+ END
+ POPUP "&Options"
+ BEGIN
+ MENUITEM "&Stretch", IDM_OPTIONS_STRETCH, CHECKED
+ END
+ POPUP "&Help"
+ BEGIN
+ MENUITEM "&About", IDM_HELP_ABOUT
+ END
+END
+
+
+/////////////////////////////////////////////////////////////////////////////
+//
+// Accelerator
+//
+
+VISUALPNG ACCELERATORS DISCARDABLE
+BEGIN
+ "N", IDM_FILE_NEXT, VIRTKEY, CONTROL, NOINVERT
+ "O", IDM_FILE_OPEN, VIRTKEY, CONTROL, NOINVERT
+ "P", IDM_FILE_PREVIOUS, VIRTKEY, CONTROL, NOINVERT
+ "V", IDM_FILE_PREVIOUS, VIRTKEY, CONTROL, NOINVERT
+ "X", IDM_FILE_EXIT, VIRTKEY, ALT, NOINVERT
+END
+
+
+/////////////////////////////////////////////////////////////////////////////
+//
+// Icon
+//
+
+// Icon with lowest ID value placed first to ensure application icon
+// remains consistent on all systems.
+VISUALPNG ICON DISCARDABLE "VisualPng.ico"
+
+/////////////////////////////////////////////////////////////////////////////
+//
+// Dialog
+//
+
+ABOUTBOX DIALOG DISCARDABLE 0, 0, 186, 94
+STYLE DS_MODALFRAME | WS_POPUP
+FONT 8, "MS Sans Serif"
+BEGIN
+ DEFPUSHBUTTON "OK",IDOK,68,67,50,14
+ CTEXT "VisualPng 1.0 - June 2000",IDC_STATIC,49,14,88,8
+ LTEXT "a PNG image viewer",IDC_STATIC,60,30,66,8
+ LTEXT "(c) Willem van Schaik, 2000",IDC_STATIC,48,52,90,8
+ LTEXT "to demonstrate the use of libpng in Visual C",
+ IDC_STATIC,25,38,136,8
+END
+
+
+/////////////////////////////////////////////////////////////////////////////
+//
+// DESIGNINFO
+//
+
+#ifdef APSTUDIO_INVOKED
+GUIDELINES DESIGNINFO DISCARDABLE
+BEGIN
+ "ABOUTBOX", DIALOG
+ BEGIN
+ LEFTMARGIN, 7
+ RIGHTMARGIN, 179
+ TOPMARGIN, 7
+ BOTTOMMARGIN, 87
+ END
+END
+#endif // APSTUDIO_INVOKED
+
+#endif // English (U.S.) resources
+/////////////////////////////////////////////////////////////////////////////
+
+
+
+#ifndef APSTUDIO_INVOKED
+/////////////////////////////////////////////////////////////////////////////
+//
+// Generated from the TEXTINCLUDE 3 resource.
+//
+
+
+/////////////////////////////////////////////////////////////////////////////
+#endif // not APSTUDIO_INVOKED
+
diff --git a/libpng/contrib/visupng/cexcept.h b/libpng/contrib/visupng/cexcept.h
new file mode 100644
index 0000000..5f45d76
--- /dev/null
+++ b/libpng/contrib/visupng/cexcept.h
@@ -0,0 +1,248 @@
+/*===
+cexcept.h 2.0.1 (2008-Jul-19-Sat)
+http://www.nicemice.net/cexcept/
+Adam M. Costello
+http://www.nicemice.net/amc/
+
+An interface for exception-handling in ANSI C (C89 and subsequent ISO
+standards), developed jointly with Cosmin Truta.
+
+ Copyright (c) 2000-2008 Adam M. Costello and Cosmin Truta.
+ This software may be modified only if its author and version
+ information is updated accurately, and may be redistributed
+ only if accompanied by this unaltered notice. Subject to those
+ restrictions, permission is granted to anyone to do anything
+ with this software. The copyright holders make no guarantees
+ regarding this software, and are not responsible for any damage
+ resulting from its use.
+
+The cexcept interface is not compatible with and cannot interact
+with system exceptions (like division by zero or memory segmentation
+violation), compiler-generated exceptions (like C++ exceptions), or
+other exception-handling interfaces.
+
+When using this interface across multiple .c files, do not include
+this header file directly. Instead, create a wrapper header file that
+includes this header file and then invokes the define_exception_type
+macro (see below). The .c files should then include that header file.
+
+The interface consists of one type, one well-known name, and six macros.
+
+
+define_exception_type(type_name);
+
+ This macro is used like an external declaration. It specifies
+ the type of object that gets copied from the exception thrower to
+ the exception catcher. The type_name can be any type that can be
+ assigned to, that is, a non-constant arithmetic type, struct, union,
+ or pointer. Examples:
+
+ define_exception_type(int);
+
+ enum exception { out_of_memory, bad_arguments, disk_full };
+ define_exception_type(enum exception);
+
+ struct exception { int code; const char *msg; };
+ define_exception_type(struct exception);
+
+ Because throwing an exception causes the object to be copied (not
+ just once, but twice), programmers may wish to consider size when
+ choosing the exception type.
+
+
+struct exception_context;
+
+ This type may be used after the define_exception_type() macro has
+ been invoked. A struct exception_context must be known to both
+ the thrower and the catcher. It is expected that there be one
+ context for each thread that uses exceptions. It would certainly
+ be dangerous for multiple threads to access the same context.
+ One thread can use multiple contexts, but that is likely to be
+ confusing and not typically useful. The application can allocate
+ this structure in any way it pleases--automatic, static, or dynamic.
+ The application programmer should pretend not to know the structure
+ members, which are subject to change.
+
+
+struct exception_context *the_exception_context;
+
+ The Try/Catch and Throw statements (described below) implicitly
+ refer to a context, using the name the_exception_context. It is
+ the application's responsibility to make sure that this name yields
+ the address of a mutable (non-constant) struct exception_context
+ wherever those statements are used. Subject to that constraint, the
+ application may declare a variable of this name anywhere it likes
+ (inside a function, in a parameter list, or externally), and may
+ use whatever storage class specifiers (static, extern, etc) or type
+ qualifiers (const, volatile, etc) it likes. Examples:
+
+ static struct exception_context
+ * const the_exception_context = &foo;
+
+ { struct exception_context *the_exception_context = bar; ... }
+
+ int blah(struct exception_context *the_exception_context, ...);
+
+ extern struct exception_context the_exception_context[1];
+
+ The last example illustrates a trick that avoids creating a pointer
+ object separate from the structure object.
+
+ The name could even be a macro, for example:
+
+ struct exception_context ec_array[numthreads];
+ #define the_exception_context (ec_array + thread_id)
+
+ Be aware that the_exception_context is used several times by the
+ Try/Catch/Throw macros, so it shouldn't be expensive or have side
+ effects. The expansion must be a drop-in replacement for an
+ identifier, so it's safest to put parentheses around it.
+
+
+void init_exception_context(struct exception_context *ec);
+
+ For context structures allocated statically (by an external
+ definition or using the "static" keyword), the implicit
+ initialization to all zeros is sufficient, but contexts allocated
+ by other means must be initialized using this macro before they
+ are used by a Try/Catch statement. It does no harm to initialize
+ a context more than once (by using this macro on a statically
+ allocated context, or using this macro twice on the same context),
+ but a context must not be re-initialized after it has been used by a
+ Try/Catch statement.
+
+
+Try statement
+Catch (expression) statement
+
+ The Try/Catch/Throw macros are capitalized in order to avoid
+ confusion with the C++ keywords, which have subtly different
+ semantics.
+
+ A Try/Catch statement has a syntax similar to an if/else statement,
+ except that the parenthesized expression goes after the second
+ keyword rather than the first. As with if/else, there are two
+ clauses, each of which may be a simple statement ending with a
+ semicolon or a brace-enclosed compound statement. But whereas
+ the else clause is optional, the Catch clause is required. The
+ expression must be a modifiable lvalue (something capable of being
+ assigned to) of the same type (disregarding type qualifiers) that
+ was passed to define_exception_type().
+
+ If a Throw that uses the same exception context as the Try/Catch is
+ executed within the Try clause (typically within a function called
+ by the Try clause), and the exception is not caught by a nested
+ Try/Catch statement, then a copy of the exception will be assigned
+ to the expression, and control will jump to the Catch clause. If no
+ such Throw is executed, then the assignment is not performed, and
+ the Catch clause is not executed.
+
+ The expression is not evaluated unless and until the exception is
+ caught, which is significant if it has side effects, for example:
+
+ Try foo();
+ Catch (p[++i].e) { ... }
+
+ IMPORTANT: Jumping into or out of a Try clause (for example via
+ return, break, continue, goto, longjmp) is forbidden--the compiler
+ will not complain, but bad things will happen at run-time. Jumping
+ into or out of a Catch clause is okay, and so is jumping around
+ inside a Try clause. In many cases where one is tempted to return
+ from a Try clause, it will suffice to use Throw, and then return
+ from the Catch clause. Another option is to set a flag variable and
+ use goto to jump to the end of the Try clause, then check the flag
+ after the Try/Catch statement.
+
+ IMPORTANT: The values of any non-volatile automatic variables
+ changed within the Try clause are undefined after an exception is
+ caught. Therefore, variables modified inside the Try block whose
+ values are needed later outside the Try block must either use static
+ storage or be declared with the "volatile" type qualifier.
+
+
+Throw expression;
+
+ A Throw statement is very much like a return statement, except that
+ the expression is required. Whereas return jumps back to the place
+ where the current function was called, Throw jumps back to the Catch
+ clause of the innermost enclosing Try clause. The expression must
+ be compatible with the type passed to define_exception_type(). The
+ exception must be caught, otherwise the program may crash.
+
+ Slight limitation: If the expression is a comma-expression, it must
+ be enclosed in parentheses.
+
+
+Try statement
+Catch_anonymous statement
+
+ When the value of the exception is not needed, a Try/Catch statement
+ can use Catch_anonymous instead of Catch (expression).
+
+
+Everything below this point is for the benefit of the compiler. The
+application programmer should pretend not to know any of it, because it
+is subject to change.
+
+===*/
+
+
+#ifndef CEXCEPT_H
+#define CEXCEPT_H
+
+
+#include <setjmp.h>
+
+#define define_exception_type(etype) \
+struct exception_context { \
+ jmp_buf *penv; \
+ int caught; \
+ volatile struct { etype etmp; } v; \
+}
+
+/* etmp must be volatile because the application might use automatic */
+/* storage for the_exception_context, and etmp is modified between */
+/* the calls to setjmp() and longjmp(). A wrapper struct is used to */
+/* avoid warnings about a duplicate volatile qualifier in case etype */
+/* already includes it. */
+
+#define init_exception_context(ec) ((void)((ec)->penv = 0))
+
+#define Try \
+ { \
+ jmp_buf *exception__prev, exception__env; \
+ exception__prev = the_exception_context->penv; \
+ the_exception_context->penv = &exception__env; \
+ if (setjmp(exception__env) == 0) { \
+ do
+
+#define exception__catch(action) \
+ while (the_exception_context->caught = 0, \
+ the_exception_context->caught); \
+ } \
+ else { \
+ the_exception_context->caught = 1; \
+ } \
+ the_exception_context->penv = exception__prev; \
+ } \
+ if (!the_exception_context->caught || action) { } \
+ else
+
+#define Catch(e) exception__catch(((e) = the_exception_context->v.etmp, 0))
+#define Catch_anonymous exception__catch(0)
+
+/* Try ends with do, and Catch begins with while(0) and ends with */
+/* else, to ensure that Try/Catch syntax is similar to if/else */
+/* syntax. */
+/* */
+/* The 0 in while(0) is expressed as x=0,x in order to appease */
+/* compilers that warn about constant expressions inside while(). */
+/* Most compilers should still recognize that the condition is always */
+/* false and avoid generating code for it. */
+
+#define Throw \
+ for (;; longjmp(*the_exception_context->penv, 1)) \
+ the_exception_context->v.etmp =
+
+
+#endif /* CEXCEPT_H */
diff --git a/libpng/contrib/visupng/resource.h b/libpng/contrib/visupng/resource.h
new file mode 100644
index 0000000..b62176d
--- /dev/null
+++ b/libpng/contrib/visupng/resource.h
@@ -0,0 +1,23 @@
+//{{NO_DEPENDENCIES}}
+// Microsoft Developer Studio generated include file.
+// Used by VisualPng.rc
+//
+#define IDM_FILE_OPEN 40001
+#define IDM_FILE_SAVE 40002
+#define IDM_FILE_NEXT 40003
+#define IDM_FILE_PREVIOUS 40004
+#define IDM_FILE_EXIT 40005
+#define IDM_OPTIONS_BACKGROUND 40006
+#define IDM_OPTIONS_STRETCH 40007
+#define IDM_HELP_ABOUT 40008
+
+// Next default values for new objects
+//
+#ifdef APSTUDIO_INVOKED
+#ifndef APSTUDIO_READONLY_SYMBOLS
+#define _APS_NEXT_RESOURCE_VALUE 113
+#define _APS_NEXT_COMMAND_VALUE 40009
+#define _APS_NEXT_CONTROL_VALUE 1001
+#define _APS_NEXT_SYMED_VALUE 101
+#endif
+#endif
diff --git a/libpng/example.c b/libpng/example.c
new file mode 100644
index 0000000..f8591e6
--- /dev/null
+++ b/libpng/example.c
@@ -0,0 +1,1061 @@
+
+#if 0 /* in case someone actually tries to compile this */
+
+/* example.c - an example of using libpng
+ * Last changed in libpng 1.6.15 [November 20, 2014]
+ * Maintained 1998-2014 Glenn Randers-Pehrson
+ * Maintained 1996, 1997 Andreas Dilger)
+ * Written 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ * To the extent possible under law, the authors have waived
+ * all copyright and related or neighboring rights to this file.
+ * This work is published from: United States.
+ */
+
+/* This is an example of how to use libpng to read and write PNG files.
+ * The file libpng-manual.txt is much more verbose then this. If you have not
+ * read it, do so first. This was designed to be a starting point of an
+ * implementation. This is not officially part of libpng, is hereby placed
+ * in the public domain, and therefore does not require a copyright notice.
+ *
+ * This file does not currently compile, because it is missing certain
+ * parts, like allocating memory to hold an image. You will have to
+ * supply these parts to get it to compile. For an example of a minimal
+ * working PNG reader/writer, see pngtest.c, included in this distribution;
+ * see also the programs in the contrib directory.
+ */
+
+/* The simple, but restricted, approach to reading a PNG file or data stream
+ * just requires two function calls, as in the following complete program.
+ * Writing a file just needs one function call, so long as the data has an
+ * appropriate layout.
+ *
+ * The following code reads PNG image data from a file and writes it, in a
+ * potentially new format, to a new file. While this code will compile there is
+ * minimal (insufficient) error checking; for a more realistic version look at
+ * contrib/examples/pngtopng.c
+ */
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <png.h>
+#include <zlib.h>
+
+int main(int argc, const char **argv)
+{
+ if (argc == 3)
+ {
+ png_image image; /* The control structure used by libpng */
+
+ /* Initialize the 'png_image' structure. */
+ memset(&image, 0, (sizeof image));
+ image.version = PNG_IMAGE_VERSION;
+
+ /* The first argument is the file to read: */
+ if (png_image_begin_read_from_file(&image, argv[1]) != 0)
+ {
+ png_bytep buffer;
+
+ /* Set the format in which to read the PNG file; this code chooses a
+ * simple sRGB format with a non-associated alpha channel, adequate to
+ * store most images.
+ */
+ image.format = PNG_FORMAT_RGBA;
+
+ /* Now allocate enough memory to hold the image in this format; the
+ * PNG_IMAGE_SIZE macro uses the information about the image (width,
+ * height and format) stored in 'image'.
+ */
+ buffer = malloc(PNG_IMAGE_SIZE(image));
+
+ /* If enough memory was available read the image in the desired format
+ * then write the result out to the new file. 'background' is not
+ * necessary when reading the image because the alpha channel is
+ * preserved; if it were to be removed, for example if we requested
+ * PNG_FORMAT_RGB, then either a solid background color would have to
+ * be supplied or the output buffer would have to be initialized to the
+ * actual background of the image.
+ *
+ * The fourth argument to png_image_finish_read is the 'row_stride' -
+ * this is the number of components allocated for the image in each
+ * row. It has to be at least as big as the value returned by
+ * PNG_IMAGE_ROW_STRIDE, but if you just allocate space for the
+ * default, minimum, size using PNG_IMAGE_SIZE as above you can pass
+ * zero.
+ *
+ * The final argument is a pointer to a buffer for the colormap;
+ * colormaps have exactly the same format as a row of image pixels (so
+ * you choose what format to make the colormap by setting
+ * image.format). A colormap is only returned if
+ * PNG_FORMAT_FLAG_COLORMAP is also set in image.format, so in this
+ * case NULL is passed as the final argument. If you do want to force
+ * all images into an index/color-mapped format then you can use:
+ *
+ * PNG_IMAGE_COLORMAP_SIZE(image)
+ *
+ * to find the maximum size of the colormap in bytes.
+ */
+ if (buffer != NULL &&
+ png_image_finish_read(&image, NULL/*background*/, buffer,
+ 0/*row_stride*/, NULL/*colormap*/) != 0)
+ {
+ /* Now write the image out to the second argument. In the write
+ * call 'convert_to_8bit' allows 16-bit data to be squashed down to
+ * 8 bits; this isn't necessary here because the original read was
+ * to the 8-bit format.
+ */
+ if (png_image_write_to_file(&image, argv[2], 0/*convert_to_8bit*/,
+ buffer, 0/*row_stride*/, NULL/*colormap*/) != 0)
+ {
+ /* The image has been written successfully. */
+ exit(0);
+ }
+ }
+
+ else
+ {
+ /* Calling png_free_image is optional unless the simplified API was
+ * not run to completion. In this case if there wasn't enough
+ * memory for 'buffer' we didn't complete the read, so we must free
+ * the image:
+ */
+ if (buffer == NULL)
+ png_free_image(&image);
+
+ else
+ free(buffer);
+ }
+
+ /* Something went wrong reading or writing the image. libpng stores a
+ * textual message in the 'png_image' structure:
+ */
+ fprintf(stderr, "pngtopng: error: %s\n", image.message);
+ exit (1);
+ }
+
+ fprintf(stderr, "pngtopng: usage: pngtopng input-file output-file\n");
+ exit(1);
+}
+
+/* That's it ;-) Of course you probably want to do more with PNG files than
+ * just converting them all to 32-bit RGBA PNG files; you can do that between
+ * the call to png_image_finish_read and png_image_write_to_file. You can also
+ * ask for the image data to be presented in a number of different formats. You
+ * do this by simply changing the 'format' parameter set before allocating the
+ * buffer.
+ *
+ * The format parameter consists of five flags that define various aspects of
+ * the image, you can simply add these together to get the format or you can use
+ * one of the predefined macros from png.h (as above):
+ *
+ * PNG_FORMAT_FLAG_COLOR: if set the image will have three color components per
+ * pixel (red, green and blue), if not set the image will just have one
+ * luminance (grayscale) component.
+ *
+ * PNG_FORMAT_FLAG_ALPHA: if set each pixel in the image will have an additional
+ * alpha value; a linear value that describes the degree the image pixel
+ * covers (overwrites) the contents of the existing pixel on the display.
+ *
+ * PNG_FORMAT_FLAG_LINEAR: if set the components of each pixel will be returned
+ * as a series of 16-bit linear values, if not set the components will be
+ * returned as a series of 8-bit values encoded according to the 'sRGB'
+ * standard. The 8-bit format is the normal format for images intended for
+ * direct display, because almost all display devices do the inverse of the
+ * sRGB transformation to the data they receive. The 16-bit format is more
+ * common for scientific data and image data that must be further processed;
+ * because it is linear simple math can be done on the component values.
+ * Regardless of the setting of this flag the alpha channel is always linear,
+ * although it will be 8 bits or 16 bits wide as specified by the flag.
+ *
+ * PNG_FORMAT_FLAG_BGR: if set the components of a color pixel will be returned
+ * in the order blue, then green, then red. If not set the pixel components
+ * are in the order red, then green, then blue.
+ *
+ * PNG_FORMAT_FLAG_AFIRST: if set the alpha channel (if present) precedes the
+ * color or grayscale components. If not set the alpha channel follows the
+ * components.
+ *
+ * You do not have to read directly from a file. You can read from memory or,
+ * on systems that support it, from a <stdio.h> FILE*. This is controlled by
+ * the particular png_image_read_from_ function you call at the start. Likewise
+ * on write you can write to a FILE* if your system supports it. Check the
+ * macro PNG_STDIO_SUPPORTED to see if stdio support has been included in your
+ * libpng build.
+ *
+ * If you read 16-bit (PNG_FORMAT_FLAG_LINEAR) data you may need to write it in
+ * the 8-bit format for display. You do this by setting the convert_to_8bit
+ * flag to 'true'.
+ *
+ * Don't repeatedly convert between the 8-bit and 16-bit forms. There is
+ * significant data loss when 16-bit data is converted to the 8-bit encoding and
+ * the current libpng implementation of conversion to 16-bit is also
+ * significantly lossy. The latter will be fixed in the future, but the former
+ * is unavoidable - the 8-bit format just doesn't have enough resolution.
+ */
+
+/* If your program needs more information from the PNG data it reads, or if you
+ * need to do more complex transformations, or minimize transformations, on the
+ * data you read, then you must use one of the several lower level libpng
+ * interfaces.
+ *
+ * All these interfaces require that you do your own error handling - your
+ * program must be able to arrange for control to return to your own code any
+ * time libpng encounters a problem. There are several ways to do this, but the
+ * standard way is to use the ANSI-C (C90) <setjmp.h> interface to establish a
+ * return point within your own code. You must do this if you do not use the
+ * simplified interface (above).
+ *
+ * The first step is to include the header files you need, including the libpng
+ * header file. Include any standard headers and feature test macros your
+ * program requires before including png.h:
+ */
+#include <png.h>
+
+ /* The png_jmpbuf() macro, used in error handling, became available in
+ * libpng version 1.0.6. If you want to be able to run your code with older
+ * versions of libpng, you must define the macro yourself (but only if it
+ * is not already defined by libpng!).
+ */
+
+#ifndef png_jmpbuf
+# define png_jmpbuf(png_ptr) ((png_ptr)->png_jmpbuf)
+#endif
+
+/* Check to see if a file is a PNG file using png_sig_cmp(). png_sig_cmp()
+ * returns zero if the image is a PNG and nonzero if it isn't a PNG.
+ *
+ * The function check_if_png() shown here, but not used, returns nonzero (true)
+ * if the file can be opened and is a PNG, 0 (false) otherwise.
+ *
+ * If this call is successful, and you are going to keep the file open,
+ * you should call png_set_sig_bytes(png_ptr, PNG_BYTES_TO_CHECK); once
+ * you have created the png_ptr, so that libpng knows your application
+ * has read that many bytes from the start of the file. Make sure you
+ * don't call png_set_sig_bytes() with more than 8 bytes read or give it
+ * an incorrect number of bytes read, or you will either have read too
+ * many bytes (your fault), or you are telling libpng to read the wrong
+ * number of magic bytes (also your fault).
+ *
+ * Many applications already read the first 2 or 4 bytes from the start
+ * of the image to determine the file type, so it would be easiest just
+ * to pass the bytes to png_sig_cmp() or even skip that if you know
+ * you have a PNG file, and call png_set_sig_bytes().
+ */
+#define PNG_BYTES_TO_CHECK 4
+int check_if_png(char *file_name, FILE **fp)
+{
+ char buf[PNG_BYTES_TO_CHECK];
+
+ /* Open the prospective PNG file. */
+ if ((*fp = fopen(file_name, "rb")) == NULL)
+ return 0;
+
+ /* Read in some of the signature bytes */
+ if (fread(buf, 1, PNG_BYTES_TO_CHECK, *fp) != PNG_BYTES_TO_CHECK)
+ return 0;
+
+ /* Compare the first PNG_BYTES_TO_CHECK bytes of the signature.
+ Return nonzero (true) if they match */
+
+ return(!png_sig_cmp(buf, (png_size_t)0, PNG_BYTES_TO_CHECK));
+}
+
+/* Read a PNG file. You may want to return an error code if the read
+ * fails (depending upon the failure). There are two "prototypes" given
+ * here - one where we are given the filename, and we need to open the
+ * file, and the other where we are given an open file (possibly with
+ * some or all of the magic bytes read - see comments above).
+ */
+#ifdef open_file /* prototype 1 */
+void read_png(char *file_name) /* We need to open the file */
+{
+ png_structp png_ptr;
+ png_infop info_ptr;
+ int sig_read = 0;
+ png_uint_32 width, height;
+ int bit_depth, color_type, interlace_type;
+ FILE *fp;
+
+ if ((fp = fopen(file_name, "rb")) == NULL)
+ return (ERROR);
+
+#else no_open_file /* prototype 2 */
+void read_png(FILE *fp, int sig_read) /* File is already open */
+{
+ png_structp png_ptr;
+ png_infop info_ptr;
+ png_uint_32 width, height;
+ int bit_depth, color_type, interlace_type;
+#endif no_open_file /* Only use one prototype! */
+
+ /* Create and initialize the png_struct with the desired error handler
+ * functions. If you want to use the default stderr and longjump method,
+ * you can supply NULL for the last three parameters. We also supply the
+ * the compiler header file version, so that we know if the application
+ * was compiled with a compatible version of the library. REQUIRED
+ */
+ png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
+ png_voidp user_error_ptr, user_error_fn, user_warning_fn);
+
+ if (png_ptr == NULL)
+ {
+ fclose(fp);
+ return (ERROR);
+ }
+
+ /* Allocate/initialize the memory for image information. REQUIRED. */
+ info_ptr = png_create_info_struct(png_ptr);
+ if (info_ptr == NULL)
+ {
+ fclose(fp);
+ png_destroy_read_struct(&png_ptr, NULL, NULL);
+ return (ERROR);
+ }
+
+ /* Set error handling if you are using the setjmp/longjmp method (this is
+ * the normal method of doing things with libpng). REQUIRED unless you
+ * set up your own error handlers in the png_create_read_struct() earlier.
+ */
+
+ if (setjmp(png_jmpbuf(png_ptr)))
+ {
+ /* Free all of the memory associated with the png_ptr and info_ptr */
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+ fclose(fp);
+ /* If we get here, we had a problem reading the file */
+ return (ERROR);
+ }
+
+ /* One of the following I/O initialization methods is REQUIRED */
+#ifdef streams /* PNG file I/O method 1 */
+ /* Set up the input control if you are using standard C streams */
+ png_init_io(png_ptr, fp);
+
+#else no_streams /* PNG file I/O method 2 */
+ /* If you are using replacement read functions, instead of calling
+ * png_init_io() here you would call:
+ */
+ png_set_read_fn(png_ptr, (void *)user_io_ptr, user_read_fn);
+ /* where user_io_ptr is a structure you want available to the callbacks */
+#endif no_streams /* Use only one I/O method! */
+
+ /* If we have already read some of the signature */
+ png_set_sig_bytes(png_ptr, sig_read);
+
+#ifdef hilevel
+ /*
+ * If you have enough memory to read in the entire image at once,
+ * and you need to specify only transforms that can be controlled
+ * with one of the PNG_TRANSFORM_* bits (this presently excludes
+ * quantizing, filling, setting background, and doing gamma
+ * adjustment), then you can read the entire image (including
+ * pixels) into the info structure with this call:
+ */
+ png_read_png(png_ptr, info_ptr, png_transforms, NULL);
+
+#else
+ /* OK, you're doing it the hard way, with the lower-level functions */
+
+ /* The call to png_read_info() gives us all of the information from the
+ * PNG file before the first IDAT (image data chunk). REQUIRED
+ */
+ png_read_info(png_ptr, info_ptr);
+
+ png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
+ &interlace_type, NULL, NULL);
+
+ /* Set up the data transformations you want. Note that these are all
+ * optional. Only call them if you want/need them. Many of the
+ * transformations only work on specific types of images, and many
+ * are mutually exclusive.
+ */
+
+ /* Tell libpng to strip 16 bits/color files down to 8 bits/color.
+ * Use accurate scaling if it's available, otherwise just chop off the
+ * low byte.
+ */
+#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
+ png_set_scale_16(png_ptr);
+#else
+ png_set_strip_16(png_ptr);
+#endif
+
+ /* Strip alpha bytes from the input data without combining with the
+ * background (not recommended).
+ */
+ png_set_strip_alpha(png_ptr);
+
+ /* Extract multiple pixels with bit depths of 1, 2, and 4 from a single
+ * byte into separate bytes (useful for paletted and grayscale images).
+ */
+ png_set_packing(png_ptr);
+
+ /* Change the order of packed pixels to least significant bit first
+ * (not useful if you are using png_set_packing). */
+ png_set_packswap(png_ptr);
+
+ /* Expand paletted colors into true RGB triplets */
+ if (color_type == PNG_COLOR_TYPE_PALETTE)
+ png_set_palette_to_rgb(png_ptr);
+
+ /* Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel */
+ if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
+ png_set_expand_gray_1_2_4_to_8(png_ptr);
+
+ /* Expand paletted or RGB images with transparency to full alpha channels
+ * so the data will be available as RGBA quartets.
+ */
+ if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS) != 0)
+ png_set_tRNS_to_alpha(png_ptr);
+
+ /* Set the background color to draw transparent and alpha images over.
+ * It is possible to set the red, green, and blue components directly
+ * for paletted images instead of supplying a palette index. Note that
+ * even if the PNG file supplies a background, you are not required to
+ * use it - you should use the (solid) application background if it has one.
+ */
+
+ png_color_16 my_background, *image_background;
+
+ if (png_get_bKGD(png_ptr, info_ptr, &image_background) != 0)
+ png_set_background(png_ptr, image_background,
+ PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
+ else
+ png_set_background(png_ptr, &my_background,
+ PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
+
+ /* Some suggestions as to how to get a screen gamma value
+ *
+ * Note that screen gamma is the display_exponent, which includes
+ * the CRT_exponent and any correction for viewing conditions
+ */
+ if (/* We have a user-defined screen gamma value */)
+ {
+ screen_gamma = user-defined screen_gamma;
+ }
+ /* This is one way that applications share the same screen gamma value */
+ else if ((gamma_str = getenv("SCREEN_GAMMA")) != NULL)
+ {
+ screen_gamma = atof(gamma_str);
+ }
+ /* If we don't have another value */
+ else
+ {
+ screen_gamma = PNG_DEFAULT_sRGB; /* A good guess for a PC monitor
+ in a dimly lit room */
+ screen_gamma = PNG_GAMMA_MAC_18 or 1.0; /* Good guesses for Mac systems */
+ }
+
+ /* Tell libpng to handle the gamma conversion for you. The final call
+ * is a good guess for PC generated images, but it should be configurable
+ * by the user at run time by the user. It is strongly suggested that
+ * your application support gamma correction.
+ */
+
+ int intent;
+
+ if (png_get_sRGB(png_ptr, info_ptr, &intent) != 0)
+ png_set_gamma(png_ptr, screen_gamma, PNG_DEFAULT_sRGB);
+ else
+ {
+ double image_gamma;
+ if (png_get_gAMA(png_ptr, info_ptr, &image_gamma) != 0)
+ png_set_gamma(png_ptr, screen_gamma, image_gamma);
+ else
+ png_set_gamma(png_ptr, screen_gamma, 0.45455);
+ }
+
+#ifdef PNG_READ_QUANTIZE_SUPPORTED
+ /* Quantize RGB files down to 8-bit palette or reduce palettes
+ * to the number of colors available on your screen.
+ */
+ if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
+ {
+ int num_palette;
+ png_colorp palette;
+
+ /* This reduces the image to the application supplied palette */
+ if (/* We have our own palette */)
+ {
+ /* An array of colors to which the image should be quantized */
+ png_color std_color_cube[MAX_SCREEN_COLORS];
+
+ png_set_quantize(png_ptr, std_color_cube, MAX_SCREEN_COLORS,
+ MAX_SCREEN_COLORS, NULL, 0);
+ }
+ /* This reduces the image to the palette supplied in the file */
+ else if (png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette) != 0)
+ {
+ png_uint_16p histogram = NULL;
+
+ png_get_hIST(png_ptr, info_ptr, &histogram);
+
+ png_set_quantize(png_ptr, palette, num_palette,
+ max_screen_colors, histogram, 0);
+ }
+ }
+#endif /* READ_QUANTIZE */
+
+ /* Invert monochrome files to have 0 as white and 1 as black */
+ png_set_invert_mono(png_ptr);
+
+ /* If you want to shift the pixel values from the range [0,255] or
+ * [0,65535] to the original [0,7] or [0,31], or whatever range the
+ * colors were originally in:
+ */
+ if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT) != 0)
+ {
+ png_color_8p sig_bit_p;
+
+ png_get_sBIT(png_ptr, info_ptr, &sig_bit_p);
+ png_set_shift(png_ptr, sig_bit_p);
+ }
+
+ /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
+ if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
+ png_set_bgr(png_ptr);
+
+ /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
+ png_set_swap_alpha(png_ptr);
+
+ /* Swap bytes of 16-bit files to least significant byte first */
+ png_set_swap(png_ptr);
+
+ /* Add filler (or alpha) byte (before/after each RGB triplet) */
+ png_set_filler(png_ptr, 0xffff, PNG_FILLER_AFTER);
+
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+ /* Turn on interlace handling. REQUIRED if you are not using
+ * png_read_image(). To see how to handle interlacing passes,
+ * see the png_read_row() method below:
+ */
+ number_passes = png_set_interlace_handling(png_ptr);
+#else
+ number_passes = 1;
+#endif /* READ_INTERLACING */
+
+
+ /* Optional call to gamma correct and add the background to the palette
+ * and update info structure. REQUIRED if you are expecting libpng to
+ * update the palette for you (ie you selected such a transform above).
+ */
+ png_read_update_info(png_ptr, info_ptr);
+
+ /* Allocate the memory to hold the image using the fields of info_ptr. */
+
+ /* The easiest way to read the image: */
+ png_bytep row_pointers[height];
+
+ /* Clear the pointer array */
+ for (row = 0; row < height; row++)
+ row_pointers[row] = NULL;
+
+ for (row = 0; row < height; row++)
+ row_pointers[row] = png_malloc(png_ptr, png_get_rowbytes(png_ptr,
+ info_ptr));
+
+ /* Now it's time to read the image. One of these methods is REQUIRED */
+#ifdef entire /* Read the entire image in one go */
+ png_read_image(png_ptr, row_pointers);
+
+#else no_entire /* Read the image one or more scanlines at a time */
+ /* The other way to read images - deal with interlacing: */
+
+ for (pass = 0; pass < number_passes; pass++)
+ {
+#ifdef single /* Read the image a single row at a time */
+ for (y = 0; y < height; y++)
+ {
+ png_read_rows(png_ptr, &row_pointers[y], NULL, 1);
+ }
+
+#else no_single /* Read the image several rows at a time */
+ for (y = 0; y < height; y += number_of_rows)
+ {
+#ifdef sparkle /* Read the image using the "sparkle" effect. */
+ png_read_rows(png_ptr, &row_pointers[y], NULL,
+ number_of_rows);
+#else no_sparkle /* Read the image using the "rectangle" effect */
+ png_read_rows(png_ptr, NULL, &row_pointers[y],
+ number_of_rows);
+#endif no_sparkle /* Use only one of these two methods */
+ }
+
+ /* If you want to display the image after every pass, do so here */
+#endif no_single /* Use only one of these two methods */
+ }
+#endif no_entire /* Use only one of these two methods */
+
+ /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
+ png_read_end(png_ptr, info_ptr);
+#endif hilevel
+
+ /* At this point you have read the entire image */
+
+ /* Clean up after the read, and free any memory allocated - REQUIRED */
+ png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+
+ /* Close the file */
+ fclose(fp);
+
+ /* That's it */
+ return (OK);
+}
+
+/* Progressively read a file */
+
+int
+initialize_png_reader(png_structp *png_ptr, png_infop *info_ptr)
+{
+ /* Create and initialize the png_struct with the desired error handler
+ * functions. If you want to use the default stderr and longjump method,
+ * you can supply NULL for the last three parameters. We also check that
+ * the library version is compatible in case we are using dynamically
+ * linked libraries.
+ */
+ *png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
+ png_voidp user_error_ptr, user_error_fn, user_warning_fn);
+
+ if (*png_ptr == NULL)
+ {
+ *info_ptr = NULL;
+ return (ERROR);
+ }
+
+ *info_ptr = png_create_info_struct(png_ptr);
+
+ if (*info_ptr == NULL)
+ {
+ png_destroy_read_struct(png_ptr, info_ptr, NULL);
+ return (ERROR);
+ }
+
+ if (setjmp(png_jmpbuf((*png_ptr))))
+ {
+ png_destroy_read_struct(png_ptr, info_ptr, NULL);
+ return (ERROR);
+ }
+
+ /* This one's new. You will need to provide all three
+ * function callbacks, even if you aren't using them all.
+ * If you aren't using all functions, you can specify NULL
+ * parameters. Even when all three functions are NULL,
+ * you need to call png_set_progressive_read_fn().
+ * These functions shouldn't be dependent on global or
+ * static variables if you are decoding several images
+ * simultaneously. You should store stream specific data
+ * in a separate struct, given as the second parameter,
+ * and retrieve the pointer from inside the callbacks using
+ * the function png_get_progressive_ptr(png_ptr).
+ */
+ png_set_progressive_read_fn(*png_ptr, (void *)stream_data,
+ info_callback, row_callback, end_callback);
+
+ return (OK);
+}
+
+int
+process_data(png_structp *png_ptr, png_infop *info_ptr,
+ png_bytep buffer, png_uint_32 length)
+{
+ if (setjmp(png_jmpbuf((*png_ptr))))
+ {
+ /* Free the png_ptr and info_ptr memory on error */
+ png_destroy_read_struct(png_ptr, info_ptr, NULL);
+ return (ERROR);
+ }
+
+ /* This one's new also. Simply give it chunks of data as
+ * they arrive from the data stream (in order, of course).
+ * On segmented machines, don't give it any more than 64K.
+ * The library seems to run fine with sizes of 4K, although
+ * you can give it much less if necessary (I assume you can
+ * give it chunks of 1 byte, but I haven't tried with less
+ * than 256 bytes yet). When this function returns, you may
+ * want to display any rows that were generated in the row
+ * callback, if you aren't already displaying them there.
+ */
+ png_process_data(*png_ptr, *info_ptr, buffer, length);
+ return (OK);
+}
+
+info_callback(png_structp png_ptr, png_infop info)
+{
+ /* Do any setup here, including setting any of the transformations
+ * mentioned in the Reading PNG files section. For now, you _must_
+ * call either png_start_read_image() or png_read_update_info()
+ * after all the transformations are set (even if you don't set
+ * any). You may start getting rows before png_process_data()
+ * returns, so this is your last chance to prepare for that.
+ */
+}
+
+row_callback(png_structp png_ptr, png_bytep new_row,
+ png_uint_32 row_num, int pass)
+{
+ /*
+ * This function is called for every row in the image. If the
+ * image is interlaced, and you turned on the interlace handler,
+ * this function will be called for every row in every pass.
+ *
+ * In this function you will receive a pointer to new row data from
+ * libpng called new_row that is to replace a corresponding row (of
+ * the same data format) in a buffer allocated by your application.
+ *
+ * The new row data pointer "new_row" may be NULL, indicating there is
+ * no new data to be replaced (in cases of interlace loading).
+ *
+ * If new_row is not NULL then you need to call
+ * png_progressive_combine_row() to replace the corresponding row as
+ * shown below:
+ */
+
+ /* Get pointer to corresponding row in our
+ * PNG read buffer.
+ */
+ png_bytep old_row = ((png_bytep *)our_data)[row_num];
+
+#ifdef PNG_READ_INTERLACING_SUPPORTED
+ /* If both rows are allocated then copy the new row
+ * data to the corresponding row data.
+ */
+ if ((old_row != NULL) && (new_row != NULL))
+ png_progressive_combine_row(png_ptr, old_row, new_row);
+
+ /*
+ * The rows and passes are called in order, so you don't really
+ * need the row_num and pass, but I'm supplying them because it
+ * may make your life easier.
+ *
+ * For the non-NULL rows of interlaced images, you must call
+ * png_progressive_combine_row() passing in the new row and the
+ * old row, as demonstrated above. You can call this function for
+ * NULL rows (it will just return) and for non-interlaced images
+ * (it just does the memcpy for you) if it will make the code
+ * easier. Thus, you can just do this for all cases:
+ */
+
+ png_progressive_combine_row(png_ptr, old_row, new_row);
+
+ /* where old_row is what was displayed for previous rows. Note
+ * that the first pass (pass == 0 really) will completely cover
+ * the old row, so the rows do not have to be initialized. After
+ * the first pass (and only for interlaced images), you will have
+ * to pass the current row as new_row, and the function will combine
+ * the old row and the new row.
+ */
+#endif /* READ_INTERLACING */
+}
+
+end_callback(png_structp png_ptr, png_infop info)
+{
+ /* This function is called when the whole image has been read,
+ * including any chunks after the image (up to and including
+ * the IEND). You will usually have the same info chunk as you
+ * had in the header, although some data may have been added
+ * to the comments and time fields.
+ *
+ * Most people won't do much here, perhaps setting a flag that
+ * marks the image as finished.
+ */
+}
+
+/* Write a png file */
+void write_png(char *file_name /* , ... other image information ... */)
+{
+ FILE *fp;
+ png_structp png_ptr;
+ png_infop info_ptr;
+ png_colorp palette;
+
+ /* Open the file */
+ fp = fopen(file_name, "wb");
+ if (fp == NULL)
+ return (ERROR);
+
+ /* Create and initialize the png_struct with the desired error handler
+ * functions. If you want to use the default stderr and longjump method,
+ * you can supply NULL for the last three parameters. We also check that
+ * the library version is compatible with the one used at compile time,
+ * in case we are using dynamically linked libraries. REQUIRED.
+ */
+ png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
+ png_voidp user_error_ptr, user_error_fn, user_warning_fn);
+
+ if (png_ptr == NULL)
+ {
+ fclose(fp);
+ return (ERROR);
+ }
+
+ /* Allocate/initialize the image information data. REQUIRED */
+ info_ptr = png_create_info_struct(png_ptr);
+ if (info_ptr == NULL)
+ {
+ fclose(fp);
+ png_destroy_write_struct(&png_ptr, NULL);
+ return (ERROR);
+ }
+
+ /* Set error handling. REQUIRED if you aren't supplying your own
+ * error handling functions in the png_create_write_struct() call.
+ */
+ if (setjmp(png_jmpbuf(png_ptr)))
+ {
+ /* If we get here, we had a problem writing the file */
+ fclose(fp);
+ png_destroy_write_struct(&png_ptr, &info_ptr);
+ return (ERROR);
+ }
+
+ /* One of the following I/O initialization functions is REQUIRED */
+
+#ifdef streams /* I/O initialization method 1 */
+ /* Set up the output control if you are using standard C streams */
+ png_init_io(png_ptr, fp);
+
+#else no_streams /* I/O initialization method 2 */
+ /* If you are using replacement write functions, instead of calling
+ * png_init_io() here you would call
+ */
+ png_set_write_fn(png_ptr, (void *)user_io_ptr, user_write_fn,
+ user_IO_flush_function);
+ /* where user_io_ptr is a structure you want available to the callbacks */
+#endif no_streams /* Only use one initialization method */
+
+#ifdef hilevel
+ /* This is the easy way. Use it if you already have all the
+ * image info living in the structure. You could "|" many
+ * PNG_TRANSFORM flags into the png_transforms integer here.
+ */
+ png_write_png(png_ptr, info_ptr, png_transforms, NULL);
+
+#else
+ /* This is the hard way */
+
+ /* Set the image information here. Width and height are up to 2^31,
+ * bit_depth is one of 1, 2, 4, 8, or 16, but valid values also depend on
+ * the color_type selected. color_type is one of PNG_COLOR_TYPE_GRAY,
+ * PNG_COLOR_TYPE_GRAY_ALPHA, PNG_COLOR_TYPE_PALETTE, PNG_COLOR_TYPE_RGB,
+ * or PNG_COLOR_TYPE_RGB_ALPHA. interlace is either PNG_INTERLACE_NONE or
+ * PNG_INTERLACE_ADAM7, and the compression_type and filter_type MUST
+ * currently be PNG_COMPRESSION_TYPE_BASE and PNG_FILTER_TYPE_BASE. REQUIRED
+ */
+ png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, PNG_COLOR_TYPE_???,
+ PNG_INTERLACE_????, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+
+ /* Set the palette if there is one. REQUIRED for indexed-color images */
+ palette = (png_colorp)png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH
+ * (sizeof (png_color)));
+ /* ... Set palette colors ... */
+ png_set_PLTE(png_ptr, info_ptr, palette, PNG_MAX_PALETTE_LENGTH);
+ /* You must not free palette here, because png_set_PLTE only makes a link to
+ * the palette that you malloced. Wait until you are about to destroy
+ * the png structure.
+ */
+
+ /* Optional significant bit (sBIT) chunk */
+ png_color_8 sig_bit;
+
+ /* If we are dealing with a grayscale image then */
+ sig_bit.gray = true_bit_depth;
+
+ /* Otherwise, if we are dealing with a color image then */
+ sig_bit.red = true_red_bit_depth;
+ sig_bit.green = true_green_bit_depth;
+ sig_bit.blue = true_blue_bit_depth;
+
+ /* If the image has an alpha channel then */
+ sig_bit.alpha = true_alpha_bit_depth;
+
+ png_set_sBIT(png_ptr, info_ptr, &sig_bit);
+
+
+ /* Optional gamma chunk is strongly suggested if you have any guess
+ * as to the correct gamma of the image.
+ */
+ png_set_gAMA(png_ptr, info_ptr, gamma);
+
+ /* Optionally write comments into the image */
+ {
+ png_text text_ptr[3];
+
+ char key0[]="Title";
+ char text0[]="Mona Lisa";
+ text_ptr[0].key = key0;
+ text_ptr[0].text = text0;
+ text_ptr[0].compression = PNG_TEXT_COMPRESSION_NONE;
+ text_ptr[0].itxt_length = 0;
+ text_ptr[0].lang = NULL;
+ text_ptr[0].lang_key = NULL;
+
+ char key1[]="Author";
+ char text1[]="Leonardo DaVinci";
+ text_ptr[1].key = key1;
+ text_ptr[1].text = text1;
+ text_ptr[1].compression = PNG_TEXT_COMPRESSION_NONE;
+ text_ptr[1].itxt_length = 0;
+ text_ptr[1].lang = NULL;
+ text_ptr[1].lang_key = NULL;
+
+ char key2[]="Description";
+ char text2[]="<long text>";
+ text_ptr[2].key = key2;
+ text_ptr[2].text = text2;
+ text_ptr[2].compression = PNG_TEXT_COMPRESSION_zTXt;
+ text_ptr[2].itxt_length = 0;
+ text_ptr[2].lang = NULL;
+ text_ptr[2].lang_key = NULL;
+
+ png_set_text(write_ptr, write_info_ptr, text_ptr, 3);
+ }
+
+ /* Other optional chunks like cHRM, bKGD, tRNS, tIME, oFFs, pHYs */
+
+ /* Note that if sRGB is present the gAMA and cHRM chunks must be ignored
+ * on read and, if your application chooses to write them, they must
+ * be written in accordance with the sRGB profile
+ */
+
+ /* Write the file header information. REQUIRED */
+ png_write_info(png_ptr, info_ptr);
+
+ /* If you want, you can write the info in two steps, in case you need to
+ * write your private chunk ahead of PLTE:
+ *
+ * png_write_info_before_PLTE(write_ptr, write_info_ptr);
+ * write_my_chunk();
+ * png_write_info(png_ptr, info_ptr);
+ *
+ * However, given the level of known- and unknown-chunk support in 1.2.0
+ * and up, this should no longer be necessary.
+ */
+
+ /* Once we write out the header, the compression type on the text
+ * chunk gets changed to PNG_TEXT_COMPRESSION_NONE_WR or
+ * PNG_TEXT_COMPRESSION_zTXt_WR, so it doesn't get written out again
+ * at the end.
+ */
+
+ /* Set up the transformations you want. Note that these are
+ * all optional. Only call them if you want them.
+ */
+
+ /* Invert monochrome pixels */
+ png_set_invert_mono(png_ptr);
+
+ /* Shift the pixels up to a legal bit depth and fill in
+ * as appropriate to correctly scale the image.
+ */
+ png_set_shift(png_ptr, &sig_bit);
+
+ /* Pack pixels into bytes */
+ png_set_packing(png_ptr);
+
+ /* Swap location of alpha bytes from ARGB to RGBA */
+ png_set_swap_alpha(png_ptr);
+
+ /* Get rid of filler (OR ALPHA) bytes, pack XRGB/RGBX/ARGB/RGBA into
+ * RGB (4 channels -> 3 channels). The second parameter is not used.
+ */
+ png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
+
+ /* Flip BGR pixels to RGB */
+ png_set_bgr(png_ptr);
+
+ /* Swap bytes of 16-bit files to most significant byte first */
+ png_set_swap(png_ptr);
+
+ /* Swap bits of 1-bit, 2-bit, 4-bit packed pixel formats */
+ png_set_packswap(png_ptr);
+
+ /* Turn on interlace handling if you are not using png_write_image() */
+ if (interlacing != 0)
+ number_passes = png_set_interlace_handling(png_ptr);
+
+ else
+ number_passes = 1;
+
+ /* The easiest way to write the image (you may have a different memory
+ * layout, however, so choose what fits your needs best). You need to
+ * use the first method if you aren't handling interlacing yourself.
+ */
+ png_uint_32 k, height, width;
+
+ /* In this example, "image" is a one-dimensional array of bytes */
+ png_byte image[height*width*bytes_per_pixel];
+
+ png_bytep row_pointers[height];
+
+ if (height > PNG_UINT_32_MAX/(sizeof (png_bytep)))
+ png_error (png_ptr, "Image is too tall to process in memory");
+
+ /* Set up pointers into your "image" byte array */
+ for (k = 0; k < height; k++)
+ row_pointers[k] = image + k*width*bytes_per_pixel;
+
+ /* One of the following output methods is REQUIRED */
+
+#ifdef entire /* Write out the entire image data in one call */
+ png_write_image(png_ptr, row_pointers);
+
+ /* The other way to write the image - deal with interlacing */
+
+#else no_entire /* Write out the image data by one or more scanlines */
+
+ /* The number of passes is either 1 for non-interlaced images,
+ * or 7 for interlaced images.
+ */
+ for (pass = 0; pass < number_passes; pass++)
+ {
+ /* Write a few rows at a time. */
+ png_write_rows(png_ptr, &row_pointers[first_row], number_of_rows);
+
+ /* If you are only writing one row at a time, this works */
+ for (y = 0; y < height; y++)
+ png_write_rows(png_ptr, &row_pointers[y], 1);
+ }
+#endif no_entire /* Use only one output method */
+
+ /* You can write optional chunks like tEXt, zTXt, and tIME at the end
+ * as well. Shouldn't be necessary in 1.2.0 and up as all the public
+ * chunks are supported and you can use png_set_unknown_chunks() to
+ * register unknown chunks into the info structure to be written out.
+ */
+
+ /* It is REQUIRED to call this to finish writing the rest of the file */
+ png_write_end(png_ptr, info_ptr);
+#endif hilevel
+
+ /* If you png_malloced a palette, free it here (don't free info_ptr->palette,
+ * as recommended in versions 1.0.5m and earlier of this example; if
+ * libpng mallocs info_ptr->palette, libpng will free it). If you
+ * allocated it with malloc() instead of png_malloc(), use free() instead
+ * of png_free().
+ */
+ png_free(png_ptr, palette);
+ palette = NULL;
+
+ /* Similarly, if you png_malloced any data that you passed in with
+ * png_set_something(), such as a hist or trans array, free it here,
+ * when you can be sure that libpng is through with it.
+ */
+ png_free(png_ptr, trans);
+ trans = NULL;
+ /* Whenever you use png_free() it is a good idea to set the pointer to
+ * NULL in case your application inadvertently tries to png_free() it
+ * again. When png_free() sees a NULL it returns without action, thus
+ * avoiding the double-free security problem.
+ */
+
+ /* Clean up after the write, and free any memory allocated */
+ png_destroy_write_struct(&png_ptr, &info_ptr);
+
+ /* Close the file */
+ fclose(fp);
+
+ /* That's it */
+ return (OK);
+}
+
+#endif /* if 0 */
diff --git a/libpng/libpng-config.in b/libpng/libpng-config.in
new file mode 100644
index 0000000..69bf8e3
--- /dev/null
+++ b/libpng/libpng-config.in
@@ -0,0 +1,127 @@
+#! /bin/sh
+
+# libpng-config
+# provides configuration info for libpng.
+
+# Copyright (C) 2002, 2004, 2006, 2007 Glenn Randers-Pehrson
+
+# This code is released under the libpng license.
+# For conditions of distribution and use, see the disclaimer
+# and license in png.h
+
+# Modeled after libxml-config.
+
+version="@PNGLIB_VERSION@"
+prefix="@prefix@"
+exec_prefix="@exec_prefix@"
+libdir="@libdir@"
+includedir="@includedir@/libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@"
+libs="-lpng@PNGLIB_MAJOR@@PNGLIB_MINOR@"
+all_libs="-lpng@PNGLIB_MAJOR@@PNGLIB_MINOR@ @LIBS@"
+I_opts="-I${includedir}"
+L_opts="-L${libdir}"
+R_opts=""
+cppflags=""
+ccopts=""
+ldopts=""
+
+usage()
+{
+ cat <<EOF
+Usage: $0 [OPTION] ...
+
+Known values for OPTION are:
+
+ --prefix print libpng prefix
+ --libdir print path to directory containing library
+ --libs print library linking information
+ --ccopts print compiler options
+ --cppflags print pre-processor flags
+ --cflags print preprocessor flags, I_opts, and compiler options
+ --I_opts print "-I" include options
+ --L_opts print linker "-L" flags for dynamic linking
+ --R_opts print dynamic linker "-R" or "-rpath" flags
+ --ldopts print linker options
+ --ldflags print linker flags (ldopts, L_opts, R_opts, and libs)
+ --static revise subsequent outputs for static linking
+ --help print this help and exit
+ --version print version information
+EOF
+
+ exit $1
+}
+
+if test $# -eq 0; then
+ usage 1
+fi
+
+while test $# -gt 0; do
+ case "$1" in
+
+ --prefix)
+ echo ${prefix}
+ ;;
+
+ --version)
+ echo ${version}
+ exit 0
+ ;;
+
+ --help)
+ usage 0
+ ;;
+
+ --ccopts)
+ echo ${ccopts}
+ ;;
+
+ --cppflags)
+ echo ${cppflags}
+ ;;
+
+ --cflags)
+ echo ${I_opts} ${cppflags} ${ccopts}
+ ;;
+
+ --libdir)
+ echo ${libdir}
+ ;;
+
+ --libs)
+ echo ${libs}
+ ;;
+
+ --I_opts)
+ echo ${I_opts}
+ ;;
+
+ --L_opts)
+ echo ${L_opts}
+ ;;
+
+ --R_opts)
+ echo ${R_opts}
+ ;;
+
+ --ldopts)
+ echo ${ldopts}
+ ;;
+
+ --ldflags)
+ echo ${ldopts} ${L_opts} ${R_opts} ${libs}
+ ;;
+
+ --static)
+ R_opts=""
+ libs=${all_libs}
+ ;;
+
+ *)
+ usage
+ exit 1
+ ;;
+ esac
+ shift
+done
+
+exit 0
diff --git a/libpng/libpng-manual.txt b/libpng/libpng-manual.txt
new file mode 100644
index 0000000..87eeb2b
--- /dev/null
+++ b/libpng/libpng-manual.txt
@@ -0,0 +1,5374 @@
+libpng-manual.txt - A description on how to use and modify libpng
+
+ libpng version 1.6.20 - December 3, 2015
+ Updated and distributed by Glenn Randers-Pehrson
+ <glennrp at users.sourceforge.net>
+ Copyright (c) 1998-2015 Glenn Randers-Pehrson
+
+ This document is released under the libpng license.
+ For conditions of distribution and use, see the disclaimer
+ and license in png.h
+
+ Based on:
+
+ libpng versions 0.97, January 1998, through 1.6.20 - December 3, 2015
+ Updated and distributed by Glenn Randers-Pehrson
+ Copyright (c) 1998-2015 Glenn Randers-Pehrson
+
+ libpng 1.0 beta 6 - version 0.96 - May 28, 1997
+ Updated and distributed by Andreas Dilger
+ Copyright (c) 1996, 1997 Andreas Dilger
+
+ libpng 1.0 beta 2 - version 0.88 - January 26, 1996
+ For conditions of distribution and use, see copyright
+ notice in png.h. Copyright (c) 1995, 1996 Guy Eric
+ Schalnat, Group 42, Inc.
+
+ Updated/rewritten per request in the libpng FAQ
+ Copyright (c) 1995, 1996 Frank J. T. Wojcik
+ December 18, 1995 & January 20, 1996
+
+ TABLE OF CONTENTS
+
+ I. Introduction
+ II. Structures
+ III. Reading
+ IV. Writing
+ V. Simplified API
+ VI. Modifying/Customizing libpng
+ VII. MNG support
+ VIII. Changes to Libpng from version 0.88
+ IX. Changes to Libpng from version 1.0.x to 1.2.x
+ X. Changes to Libpng from version 1.0.x/1.2.x to 1.4.x
+ XI. Changes to Libpng from version 1.4.x to 1.5.x
+ XII. Changes to Libpng from version 1.5.x to 1.6.x
+ XIII. Detecting libpng
+ XIV. Source code repository
+ XV. Coding style
+ XVI. Y2K Compliance in libpng
+
+I. Introduction
+
+This file describes how to use and modify the PNG reference library
+(known as libpng) for your own use. In addition to this
+file, example.c is a good starting point for using the library, as
+it is heavily commented and should include everything most people
+will need. We assume that libpng is already installed; see the
+INSTALL file for instructions on how to configure and install libpng.
+
+For examples of libpng usage, see the files "example.c", "pngtest.c",
+and the files in the "contrib" directory, all of which are included in
+the libpng distribution.
+
+Libpng was written as a companion to the PNG specification, as a way
+of reducing the amount of time and effort it takes to support the PNG
+file format in application programs.
+
+The PNG specification (second edition), November 2003, is available as
+a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2004 (E)) at
+<http://www.w3.org/TR/2003/REC-PNG-20031110/
+The W3C and ISO documents have identical technical content.
+
+The PNG-1.2 specification is available at
+<http://png-mng.sourceforge.net/pub/png/spec/1.2/>.
+It is technically equivalent
+to the PNG specification (second edition) but has some additional material.
+
+The PNG-1.0 specification is available as RFC 2083
+<http://png-mng.sourceforge.net/pub/png/spec/1.0/> and as a
+W3C Recommendation <http://www.w3.org/TR/REC-png-961001>.
+
+Some additional chunks are described in the special-purpose public chunks
+documents at <http://www.libpng.org/pub/png/spec/register/>
+
+Other information
+about PNG, and the latest version of libpng, can be found at the PNG home
+page, <http://www.libpng.org/pub/png/>.
+
+Most users will not have to modify the library significantly; advanced
+users may want to modify it more. All attempts were made to make it as
+complete as possible, while keeping the code easy to understand.
+Currently, this library only supports C. Support for other languages
+is being considered.
+
+Libpng has been designed to handle multiple sessions at one time,
+to be easily modifiable, to be portable to the vast majority of
+machines (ANSI, K&R, 16-, 32-, and 64-bit) available, and to be easy
+to use. The ultimate goal of libpng is to promote the acceptance of
+the PNG file format in whatever way possible. While there is still
+work to be done (see the TODO file), libpng should cover the
+majority of the needs of its users.
+
+Libpng uses zlib for its compression and decompression of PNG files.
+Further information about zlib, and the latest version of zlib, can
+be found at the zlib home page, <http://zlib.net/>.
+The zlib compression utility is a general purpose utility that is
+useful for more than PNG files, and can be used without libpng.
+See the documentation delivered with zlib for more details.
+You can usually find the source files for the zlib utility wherever you
+find the libpng source files.
+
+Libpng is thread safe, provided the threads are using different
+instances of the structures. Each thread should have its own
+png_struct and png_info instances, and thus its own image.
+Libpng does not protect itself against two threads using the
+same instance of a structure.
+
+II. Structures
+
+There are two main structures that are important to libpng, png_struct
+and png_info. Both are internal structures that are no longer exposed
+in the libpng interface (as of libpng 1.5.0).
+
+The png_info structure is designed to provide information about the
+PNG file. At one time, the fields of png_info were intended to be
+directly accessible to the user. However, this tended to cause problems
+with applications using dynamically loaded libraries, and as a result
+a set of interface functions for png_info (the png_get_*() and png_set_*()
+functions) was developed, and direct access to the png_info fields was
+deprecated..
+
+The png_struct structure is the object used by the library to decode a
+single image. As of 1.5.0 this structure is also not exposed.
+
+Almost all libpng APIs require a pointer to a png_struct as the first argument.
+Many (in particular the png_set and png_get APIs) also require a pointer
+to png_info as the second argument. Some application visible macros
+defined in png.h designed for basic data access (reading and writing
+integers in the PNG format) don't take a png_info pointer, but it's almost
+always safe to assume that a (png_struct*) has to be passed to call an API
+function.
+
+You can have more than one png_info structure associated with an image,
+as illustrated in pngtest.c, one for information valid prior to the
+IDAT chunks and another (called "end_info" below) for things after them.
+
+The png.h header file is an invaluable reference for programming with libpng.
+And while I'm on the topic, make sure you include the libpng header file:
+
+#include <png.h>
+
+and also (as of libpng-1.5.0) the zlib header file, if you need it:
+
+#include <zlib.h>
+
+Types
+
+The png.h header file defines a number of integral types used by the
+APIs. Most of these are fairly obvious; for example types corresponding
+to integers of particular sizes and types for passing color values.
+
+One exception is how non-integral numbers are handled. For application
+convenience most APIs that take such numbers have C (double) arguments;
+however, internally PNG, and libpng, use 32 bit signed integers and encode
+the value by multiplying by 100,000. As of libpng 1.5.0 a convenience
+macro PNG_FP_1 is defined in png.h along with a type (png_fixed_point)
+which is simply (png_int_32).
+
+All APIs that take (double) arguments also have a matching API that
+takes the corresponding fixed point integer arguments. The fixed point
+API has the same name as the floating point one with "_fixed" appended.
+The actual range of values permitted in the APIs is frequently less than
+the full range of (png_fixed_point) (-21474 to +21474). When APIs require
+a non-negative argument the type is recorded as png_uint_32 above. Consult
+the header file and the text below for more information.
+
+Special care must be take with sCAL chunk handling because the chunk itself
+uses non-integral values encoded as strings containing decimal floating point
+numbers. See the comments in the header file.
+
+Configuration
+
+The main header file function declarations are frequently protected by C
+preprocessing directives of the form:
+
+ #ifdef PNG_feature_SUPPORTED
+ declare-function
+ #endif
+ ...
+ #ifdef PNG_feature_SUPPORTED
+ use-function
+ #endif
+
+The library can be built without support for these APIs, although a
+standard build will have all implemented APIs. Application programs
+should check the feature macros before using an API for maximum
+portability. From libpng 1.5.0 the feature macros set during the build
+of libpng are recorded in the header file "pnglibconf.h" and this file
+is always included by png.h.
+
+If you don't need to change the library configuration from the default, skip to
+the next section ("Reading").
+
+Notice that some of the makefiles in the 'scripts' directory and (in 1.5.0) all
+of the build project files in the 'projects' directory simply copy
+scripts/pnglibconf.h.prebuilt to pnglibconf.h. This means that these build
+systems do not permit easy auto-configuration of the library - they only
+support the default configuration.
+
+The easiest way to make minor changes to the libpng configuration when
+auto-configuration is supported is to add definitions to the command line
+using (typically) CPPFLAGS. For example:
+
+CPPFLAGS=-DPNG_NO_FLOATING_ARITHMETIC
+
+will change the internal libpng math implementation for gamma correction and
+other arithmetic calculations to fixed point, avoiding the need for fast
+floating point support. The result can be seen in the generated pnglibconf.h -
+make sure it contains the changed feature macro setting.
+
+If you need to make more extensive configuration changes - more than one or two
+feature macro settings - you can either add -DPNG_USER_CONFIG to the build
+command line and put a list of feature macro settings in pngusr.h or you can set
+DFA_XTRA (a makefile variable) to a file containing the same information in the
+form of 'option' settings.
+
+A. Changing pnglibconf.h
+
+A variety of methods exist to build libpng. Not all of these support
+reconfiguration of pnglibconf.h. To reconfigure pnglibconf.h it must either be
+rebuilt from scripts/pnglibconf.dfa using awk or it must be edited by hand.
+
+Hand editing is achieved by copying scripts/pnglibconf.h.prebuilt to
+pnglibconf.h and changing the lines defining the supported features, paying
+very close attention to the 'option' information in scripts/pnglibconf.dfa
+that describes those features and their requirements. This is easy to get
+wrong.
+
+B. Configuration using DFA_XTRA
+
+Rebuilding from pnglibconf.dfa is easy if a functioning 'awk', or a later
+variant such as 'nawk' or 'gawk', is available. The configure build will
+automatically find an appropriate awk and build pnglibconf.h.
+The scripts/pnglibconf.mak file contains a set of make rules for doing the
+same thing if configure is not used, and many of the makefiles in the scripts
+directory use this approach.
+
+When rebuilding simply write a new file containing changed options and set
+DFA_XTRA to the name of this file. This causes the build to append the new file
+to the end of scripts/pnglibconf.dfa. The pngusr.dfa file should contain lines
+of the following forms:
+
+everything = off
+
+This turns all optional features off. Include it at the start of pngusr.dfa to
+make it easier to build a minimal configuration. You will need to turn at least
+some features on afterward to enable either reading or writing code, or both.
+
+option feature on
+option feature off
+
+Enable or disable a single feature. This will automatically enable other
+features required by a feature that is turned on or disable other features that
+require a feature which is turned off. Conflicting settings will cause an error
+message to be emitted by awk.
+
+setting feature default value
+
+Changes the default value of setting 'feature' to 'value'. There are a small
+number of settings listed at the top of pnglibconf.h, they are documented in the
+source code. Most of these values have performance implications for the library
+but most of them have no visible effect on the API. Some can also be overridden
+from the API.
+
+This method of building a customized pnglibconf.h is illustrated in
+contrib/pngminim/*. See the "$(PNGCONF):" target in the makefile and
+pngusr.dfa in these directories.
+
+C. Configuration using PNG_USER_CONFIG
+
+If -DPNG_USER_CONFIG is added to the CPPFLAGS when pnglibconf.h is built,
+the file pngusr.h will automatically be included before the options in
+scripts/pnglibconf.dfa are processed. Your pngusr.h file should contain only
+macro definitions turning features on or off or setting settings.
+
+Apart from the global setting "everything = off" all the options listed above
+can be set using macros in pngusr.h:
+
+#define PNG_feature_SUPPORTED
+
+is equivalent to:
+
+option feature on
+
+#define PNG_NO_feature
+
+is equivalent to:
+
+option feature off
+
+#define PNG_feature value
+
+is equivalent to:
+
+setting feature default value
+
+Notice that in both cases, pngusr.dfa and pngusr.h, the contents of the
+pngusr file you supply override the contents of scripts/pnglibconf.dfa
+
+If confusing or incomprehensible behavior results it is possible to
+examine the intermediate file pnglibconf.dfn to find the full set of
+dependency information for each setting and option. Simply locate the
+feature in the file and read the C comments that precede it.
+
+This method is also illustrated in the contrib/pngminim/* makefiles and
+pngusr.h.
+
+III. Reading
+
+We'll now walk you through the possible functions to call when reading
+in a PNG file sequentially, briefly explaining the syntax and purpose
+of each one. See example.c and png.h for more detail. While
+progressive reading is covered in the next section, you will still
+need some of the functions discussed in this section to read a PNG
+file.
+
+Setup
+
+You will want to do the I/O initialization(*) before you get into libpng,
+so if it doesn't work, you don't have much to undo. Of course, you
+will also want to insure that you are, in fact, dealing with a PNG
+file. Libpng provides a simple check to see if a file is a PNG file.
+To use it, pass in the first 1 to 8 bytes of the file to the function
+png_sig_cmp(), and it will return 0 (false) if the bytes match the
+corresponding bytes of the PNG signature, or nonzero (true) otherwise.
+Of course, the more bytes you pass in, the greater the accuracy of the
+prediction.
+
+If you are intending to keep the file pointer open for use in libpng,
+you must ensure you don't read more than 8 bytes from the beginning
+of the file, and you also have to make a call to png_set_sig_bytes()
+with the number of bytes you read from the beginning. Libpng will
+then only check the bytes (if any) that your program didn't read.
+
+(*): If you are not using the standard I/O functions, you will need
+to replace them with custom functions. See the discussion under
+Customizing libpng.
+
+ FILE *fp = fopen(file_name, "rb");
+ if (!fp)
+ {
+ return (ERROR);
+ }
+
+ if (fread(header, 1, number, fp) != number)
+ {
+ return (ERROR);
+ }
+
+ is_png = !png_sig_cmp(header, 0, number);
+ if (!is_png)
+ {
+ return (NOT_PNG);
+ }
+
+Next, png_struct and png_info need to be allocated and initialized. In
+order to ensure that the size of these structures is correct even with a
+dynamically linked libpng, there are functions to initialize and
+allocate the structures. We also pass the library version, optional
+pointers to error handling functions, and a pointer to a data struct for
+use by the error functions, if necessary (the pointer and functions can
+be NULL if the default error handlers are to be used). See the section
+on Changes to Libpng below regarding the old initialization functions.
+The structure allocation functions quietly return NULL if they fail to
+create the structure, so your application should check for that.
+
+ png_structp png_ptr = png_create_read_struct
+ (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+ user_error_fn, user_warning_fn);
+
+ if (!png_ptr)
+ return (ERROR);
+
+ png_infop info_ptr = png_create_info_struct(png_ptr);
+
+ if (!info_ptr)
+ {
+ png_destroy_read_struct(&png_ptr,
+ (png_infopp)NULL, (png_infopp)NULL);
+ return (ERROR);
+ }
+
+If you want to use your own memory allocation routines,
+use a libpng that was built with PNG_USER_MEM_SUPPORTED defined, and use
+png_create_read_struct_2() instead of png_create_read_struct():
+
+ png_structp png_ptr = png_create_read_struct_2
+ (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+ user_error_fn, user_warning_fn, (png_voidp)
+ user_mem_ptr, user_malloc_fn, user_free_fn);
+
+The error handling routines passed to png_create_read_struct()
+and the memory alloc/free routines passed to png_create_struct_2()
+are only necessary if you are not using the libpng supplied error
+handling and memory alloc/free functions.
+
+When libpng encounters an error, it expects to longjmp back
+to your routine. Therefore, you will need to call setjmp and pass
+your png_jmpbuf(png_ptr). If you read the file from different
+routines, you will need to update the longjmp buffer every time you enter
+a new routine that will call a png_*() function.
+
+See your documentation of setjmp/longjmp for your compiler for more
+information on setjmp/longjmp. See the discussion on libpng error
+handling in the Customizing Libpng section below for more information
+on the libpng error handling. If an error occurs, and libpng longjmp's
+back to your setjmp, you will want to call png_destroy_read_struct() to
+free any memory.
+
+ if (setjmp(png_jmpbuf(png_ptr)))
+ {
+ png_destroy_read_struct(&png_ptr, &info_ptr,
+ &end_info);
+ fclose(fp);
+ return (ERROR);
+ }
+
+Pass (png_infopp)NULL instead of &end_info if you didn't create
+an end_info structure.
+
+If you would rather avoid the complexity of setjmp/longjmp issues,
+you can compile libpng with PNG_NO_SETJMP, in which case
+errors will result in a call to PNG_ABORT() which defaults to abort().
+
+You can #define PNG_ABORT() to a function that does something
+more useful than abort(), as long as your function does not
+return.
+
+Now you need to set up the input code. The default for libpng is to
+use the C function fread(). If you use this, you will need to pass a
+valid FILE * in the function png_init_io(). Be sure that the file is
+opened in binary mode. If you wish to handle reading data in another
+way, you need not call the png_init_io() function, but you must then
+implement the libpng I/O methods discussed in the Customizing Libpng
+section below.
+
+ png_init_io(png_ptr, fp);
+
+If you had previously opened the file and read any of the signature from
+the beginning in order to see if this was a PNG file, you need to let
+libpng know that there are some bytes missing from the start of the file.
+
+ png_set_sig_bytes(png_ptr, number);
+
+You can change the zlib compression buffer size to be used while
+reading compressed data with
+
+ png_set_compression_buffer_size(png_ptr, buffer_size);
+
+where the default size is 8192 bytes. Note that the buffer size
+is changed immediately and the buffer is reallocated immediately,
+instead of setting a flag to be acted upon later.
+
+If you want CRC errors to be handled in a different manner than
+the default, use
+
+ png_set_crc_action(png_ptr, crit_action, ancil_action);
+
+The values for png_set_crc_action() say how libpng is to handle CRC errors in
+ancillary and critical chunks, and whether to use the data contained
+therein. Note that it is impossible to "discard" data in a critical
+chunk.
+
+Choices for (int) crit_action are
+ PNG_CRC_DEFAULT 0 error/quit
+ PNG_CRC_ERROR_QUIT 1 error/quit
+ PNG_CRC_WARN_USE 3 warn/use data
+ PNG_CRC_QUIET_USE 4 quiet/use data
+ PNG_CRC_NO_CHANGE 5 use the current value
+
+Choices for (int) ancil_action are
+ PNG_CRC_DEFAULT 0 error/quit
+ PNG_CRC_ERROR_QUIT 1 error/quit
+ PNG_CRC_WARN_DISCARD 2 warn/discard data
+ PNG_CRC_WARN_USE 3 warn/use data
+ PNG_CRC_QUIET_USE 4 quiet/use data
+ PNG_CRC_NO_CHANGE 5 use the current value
+
+Setting up callback code
+
+You can set up a callback function to handle any unknown chunks in the
+input stream. You must supply the function
+
+ read_chunk_callback(png_structp png_ptr,
+ png_unknown_chunkp chunk);
+ {
+ /* The unknown chunk structure contains your
+ chunk data, along with similar data for any other
+ unknown chunks: */
+
+ png_byte name[5];
+ png_byte *data;
+ png_size_t size;
+
+ /* Note that libpng has already taken care of
+ the CRC handling */
+
+ /* put your code here. Search for your chunk in the
+ unknown chunk structure, process it, and return one
+ of the following: */
+
+ return (-n); /* chunk had an error */
+ return (0); /* did not recognize */
+ return (n); /* success */
+ }
+
+(You can give your function another name that you like instead of
+"read_chunk_callback")
+
+To inform libpng about your function, use
+
+ png_set_read_user_chunk_fn(png_ptr, user_chunk_ptr,
+ read_chunk_callback);
+
+This names not only the callback function, but also a user pointer that
+you can retrieve with
+
+ png_get_user_chunk_ptr(png_ptr);
+
+If you call the png_set_read_user_chunk_fn() function, then all unknown
+chunks which the callback does not handle will be saved when read. You can
+cause them to be discarded by returning '1' ("handled") instead of '0'. This
+behavior will change in libpng 1.7 and the default handling set by the
+png_set_keep_unknown_chunks() function, described below, will be used when the
+callback returns 0. If you want the existing behavior you should set the global
+default to PNG_HANDLE_CHUNK_IF_SAFE now; this is compatible with all current
+versions of libpng and with 1.7. Libpng 1.6 issues a warning if you keep the
+default, or PNG_HANDLE_CHUNK_NEVER, and the callback returns 0.
+
+At this point, you can set up a callback function that will be
+called after each row has been read, which you can use to control
+a progress meter or the like. It's demonstrated in pngtest.c.
+You must supply a function
+
+ void read_row_callback(png_structp png_ptr,
+ png_uint_32 row, int pass);
+ {
+ /* put your code here */
+ }
+
+(You can give it another name that you like instead of "read_row_callback")
+
+To inform libpng about your function, use
+
+ png_set_read_status_fn(png_ptr, read_row_callback);
+
+When this function is called the row has already been completely processed and
+the 'row' and 'pass' refer to the next row to be handled. For the
+non-interlaced case the row that was just handled is simply one less than the
+passed in row number, and pass will always be 0. For the interlaced case the
+same applies unless the row value is 0, in which case the row just handled was
+the last one from one of the preceding passes. Because interlacing may skip a
+pass you cannot be sure that the preceding pass is just 'pass-1', if you really
+need to know what the last pass is record (row,pass) from the callback and use
+the last recorded value each time.
+
+As with the user transform you can find the output row using the
+PNG_ROW_FROM_PASS_ROW macro.
+
+Unknown-chunk handling
+
+Now you get to set the way the library processes unknown chunks in the
+input PNG stream. Both known and unknown chunks will be read. Normal
+behavior is that known chunks will be parsed into information in
+various info_ptr members while unknown chunks will be discarded. This
+behavior can be wasteful if your application will never use some known
+chunk types. To change this, you can call:
+
+ png_set_keep_unknown_chunks(png_ptr, keep,
+ chunk_list, num_chunks);
+
+ keep - 0: default unknown chunk handling
+ 1: ignore; do not keep
+ 2: keep only if safe-to-copy
+ 3: keep even if unsafe-to-copy
+
+ You can use these definitions:
+ PNG_HANDLE_CHUNK_AS_DEFAULT 0
+ PNG_HANDLE_CHUNK_NEVER 1
+ PNG_HANDLE_CHUNK_IF_SAFE 2
+ PNG_HANDLE_CHUNK_ALWAYS 3
+
+ chunk_list - list of chunks affected (a byte string,
+ five bytes per chunk, NULL or '\0' if
+ num_chunks is positive; ignored if
+ numchunks <= 0).
+
+ num_chunks - number of chunks affected; if 0, all
+ unknown chunks are affected. If positive,
+ only the chunks in the list are affected,
+ and if negative all unknown chunks and
+ all known chunks except for the IHDR,
+ PLTE, tRNS, IDAT, and IEND chunks are
+ affected.
+
+Unknown chunks declared in this way will be saved as raw data onto a
+list of png_unknown_chunk structures. If a chunk that is normally
+known to libpng is named in the list, it will be handled as unknown,
+according to the "keep" directive. If a chunk is named in successive
+instances of png_set_keep_unknown_chunks(), the final instance will
+take precedence. The IHDR and IEND chunks should not be named in
+chunk_list; if they are, libpng will process them normally anyway.
+If you know that your application will never make use of some particular
+chunks, use PNG_HANDLE_CHUNK_NEVER (or 1) as demonstrated below.
+
+Here is an example of the usage of png_set_keep_unknown_chunks(),
+where the private "vpAg" chunk will later be processed by a user chunk
+callback function:
+
+ png_byte vpAg[5]={118, 112, 65, 103, (png_byte) '\0'};
+
+ #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
+ png_byte unused_chunks[]=
+ {
+ 104, 73, 83, 84, (png_byte) '\0', /* hIST */
+ 105, 84, 88, 116, (png_byte) '\0', /* iTXt */
+ 112, 67, 65, 76, (png_byte) '\0', /* pCAL */
+ 115, 67, 65, 76, (png_byte) '\0', /* sCAL */
+ 115, 80, 76, 84, (png_byte) '\0', /* sPLT */
+ 116, 73, 77, 69, (png_byte) '\0', /* tIME */
+ };
+ #endif
+
+ ...
+
+ #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
+ /* ignore all unknown chunks
+ * (use global setting "2" for libpng16 and earlier):
+ */
+ png_set_keep_unknown_chunks(read_ptr, 2, NULL, 0);
+
+ /* except for vpAg: */
+ png_set_keep_unknown_chunks(read_ptr, 2, vpAg, 1);
+
+ /* also ignore unused known chunks: */
+ png_set_keep_unknown_chunks(read_ptr, 1, unused_chunks,
+ (int)(sizeof unused_chunks)/5);
+ #endif
+
+User limits
+
+The PNG specification allows the width and height of an image to be as
+large as 2^31-1 (0x7fffffff), or about 2.147 billion rows and columns.
+For safety, libpng imposes a default limit of 1 million rows and columns.
+Larger images will be rejected immediately with a png_error() call. If
+you wish to change these limits, you can use
+
+ png_set_user_limits(png_ptr, width_max, height_max);
+
+to set your own limits (libpng may reject some very wide images
+anyway because of potential buffer overflow conditions).
+
+You should put this statement after you create the PNG structure and
+before calling png_read_info(), png_read_png(), or png_process_data().
+
+When writing a PNG datastream, put this statement before calling
+png_write_info() or png_write_png().
+
+If you need to retrieve the limits that are being applied, use
+
+ width_max = png_get_user_width_max(png_ptr);
+ height_max = png_get_user_height_max(png_ptr);
+
+The PNG specification sets no limit on the number of ancillary chunks
+allowed in a PNG datastream. By default, libpng imposes a limit of
+a total of 1000 sPLT, tEXt, iTXt, zTXt, and unknown chunks to be stored.
+If you have set up both info_ptr and end_info_ptr, the limit applies
+separately to each. You can change the limit on the total number of such
+chunks that will be stored, with
+
+ png_set_chunk_cache_max(png_ptr, user_chunk_cache_max);
+
+where 0x7fffffffL means unlimited. You can retrieve this limit with
+
+ chunk_cache_max = png_get_chunk_cache_max(png_ptr);
+
+Libpng imposes a limit of 8 Megabytes (8,000,000 bytes) on the amount of
+memory that a compressed chunk other than IDAT can occupy, when decompressed.
+You can change this limit with
+
+ png_set_chunk_malloc_max(png_ptr, user_chunk_malloc_max);
+
+and you can retrieve the limit with
+
+ chunk_malloc_max = png_get_chunk_malloc_max(png_ptr);
+
+Any chunks that would cause either of these limits to be exceeded will
+be ignored.
+
+Information about your system
+
+If you intend to display the PNG or to incorporate it in other image data you
+need to tell libpng information about your display or drawing surface so that
+libpng can convert the values in the image to match the display.
+
+From libpng-1.5.4 this information can be set before reading the PNG file
+header. In earlier versions png_set_gamma() existed but behaved incorrectly if
+called before the PNG file header had been read and png_set_alpha_mode() did not
+exist.
+
+If you need to support versions prior to libpng-1.5.4 test the version number
+as illustrated below using "PNG_LIBPNG_VER >= 10504" and follow the procedures
+described in the appropriate manual page.
+
+You give libpng the encoding expected by your system expressed as a 'gamma'
+value. You can also specify a default encoding for the PNG file in
+case the required information is missing from the file. By default libpng
+assumes that the PNG data matches your system, to keep this default call:
+
+ png_set_gamma(png_ptr, screen_gamma, output_gamma);
+
+or you can use the fixed point equivalent:
+
+ png_set_gamma_fixed(png_ptr, PNG_FP_1*screen_gamma,
+ PNG_FP_1*output_gamma);
+
+If you don't know the gamma for your system it is probably 2.2 - a good
+approximation to the IEC standard for display systems (sRGB). If images are
+too contrasty or washed out you got the value wrong - check your system
+documentation!
+
+Many systems permit the system gamma to be changed via a lookup table in the
+display driver, a few systems, including older Macs, change the response by
+default. As of 1.5.4 three special values are available to handle common
+situations:
+
+ PNG_DEFAULT_sRGB: Indicates that the system conforms to the
+ IEC 61966-2-1 standard. This matches almost
+ all systems.
+ PNG_GAMMA_MAC_18: Indicates that the system is an older
+ (pre Mac OS 10.6) Apple Macintosh system with
+ the default settings.
+ PNG_GAMMA_LINEAR: Just the fixed point value for 1.0 - indicates
+ that the system expects data with no gamma
+ encoding.
+
+You would use the linear (unencoded) value if you need to process the pixel
+values further because this avoids the need to decode and re-encode each
+component value whenever arithmetic is performed. A lot of graphics software
+uses linear values for this reason, often with higher precision component values
+to preserve overall accuracy.
+
+
+The output_gamma value expresses how to decode the output values, not how
+they are encoded. The values used correspond to the normal numbers used to
+describe the overall gamma of a computer display system; for example 2.2 for
+an sRGB conformant system. The values are scaled by 100000 in the _fixed
+version of the API (so 220000 for sRGB.)
+
+The inverse of the value is always used to provide a default for the PNG file
+encoding if it has no gAMA chunk and if png_set_gamma() has not been called
+to override the PNG gamma information.
+
+When the ALPHA_OPTIMIZED mode is selected the output gamma is used to encode
+opaque pixels however pixels with lower alpha values are not encoded,
+regardless of the output gamma setting.
+
+When the standard Porter Duff handling is requested with mode 1 the output
+encoding is set to be linear and the output_gamma value is only relevant
+as a default for input data that has no gamma information. The linear output
+encoding will be overridden if png_set_gamma() is called - the results may be
+highly unexpected!
+
+The following numbers are derived from the sRGB standard and the research
+behind it. sRGB is defined to be approximated by a PNG gAMA chunk value of
+0.45455 (1/2.2) for PNG. The value implicitly includes any viewing
+correction required to take account of any differences in the color
+environment of the original scene and the intended display environment; the
+value expresses how to *decode* the image for display, not how the original
+data was *encoded*.
+
+sRGB provides a peg for the PNG standard by defining a viewing environment.
+sRGB itself, and earlier TV standards, actually use a more complex transform
+(a linear portion then a gamma 2.4 power law) than PNG can express. (PNG is
+limited to simple power laws.) By saying that an image for direct display on
+an sRGB conformant system should be stored with a gAMA chunk value of 45455
+(11.3.3.2 and 11.3.3.5 of the ISO PNG specification) the PNG specification
+makes it possible to derive values for other display systems and
+environments.
+
+The Mac value is deduced from the sRGB based on an assumption that the actual
+extra viewing correction used in early Mac display systems was implemented as
+a power 1.45 lookup table.
+
+Any system where a programmable lookup table is used or where the behavior of
+the final display device characteristics can be changed requires system
+specific code to obtain the current characteristic. However this can be
+difficult and most PNG gamma correction only requires an approximate value.
+
+By default, if png_set_alpha_mode() is not called, libpng assumes that all
+values are unencoded, linear, values and that the output device also has a
+linear characteristic. This is only very rarely correct - it is invariably
+better to call png_set_alpha_mode() with PNG_DEFAULT_sRGB than rely on the
+default if you don't know what the right answer is!
+
+The special value PNG_GAMMA_MAC_18 indicates an older Mac system (pre Mac OS
+10.6) which used a correction table to implement a somewhat lower gamma on an
+otherwise sRGB system.
+
+Both these values are reserved (not simple gamma values) in order to allow
+more precise correction internally in the future.
+
+NOTE: the values can be passed to either the fixed or floating
+point APIs, but the floating point API will also accept floating point
+values.
+
+The second thing you may need to tell libpng about is how your system handles
+alpha channel information. Some, but not all, PNG files contain an alpha
+channel. To display these files correctly you need to compose the data onto a
+suitable background, as described in the PNG specification.
+
+Libpng only supports composing onto a single color (using png_set_background;
+see below). Otherwise you must do the composition yourself and, in this case,
+you may need to call png_set_alpha_mode:
+
+ #if PNG_LIBPNG_VER >= 10504
+ png_set_alpha_mode(png_ptr, mode, screen_gamma);
+ #else
+ png_set_gamma(png_ptr, screen_gamma, 1.0/screen_gamma);
+ #endif
+
+The screen_gamma value is the same as the argument to png_set_gamma; however,
+how it affects the output depends on the mode. png_set_alpha_mode() sets the
+file gamma default to 1/screen_gamma, so normally you don't need to call
+png_set_gamma. If you need different defaults call png_set_gamma() before
+png_set_alpha_mode() - if you call it after it will override the settings made
+by png_set_alpha_mode().
+
+The mode is as follows:
+
+ PNG_ALPHA_PNG: The data is encoded according to the PNG
+specification. Red, green and blue, or gray, components are
+gamma encoded color values and are not premultiplied by the
+alpha value. The alpha value is a linear measure of the
+contribution of the pixel to the corresponding final output pixel.
+
+You should normally use this format if you intend to perform
+color correction on the color values; most, maybe all, color
+correction software has no handling for the alpha channel and,
+anyway, the math to handle pre-multiplied component values is
+unnecessarily complex.
+
+Before you do any arithmetic on the component values you need
+to remove the gamma encoding and multiply out the alpha
+channel. See the PNG specification for more detail. It is
+important to note that when an image with an alpha channel is
+scaled, linear encoded, pre-multiplied component values must
+be used!
+
+The remaining modes assume you don't need to do any further color correction or
+that if you do, your color correction software knows all about alpha (it
+probably doesn't!). They 'associate' the alpha with the color information by
+storing color channel values that have been scaled by the alpha. The
+advantage is that the color channels can be resampled (the image can be
+scaled) in this form. The disadvantage is that normal practice is to store
+linear, not (gamma) encoded, values and this requires 16-bit channels for
+still images rather than the 8-bit channels that are just about sufficient if
+gamma encoding is used. In addition all non-transparent pixel values,
+including completely opaque ones, must be gamma encoded to produce the final
+image. These are the 'STANDARD', 'ASSOCIATED' or 'PREMULTIPLIED' modes
+described below (the latter being the two common names for associated alpha
+color channels). Note that PNG files always contain non-associated color
+channels; png_set_alpha_mode() with one of the modes causes the decoder to
+convert the pixels to an associated form before returning them to your
+application.
+
+Since it is not necessary to perform arithmetic on opaque color values so
+long as they are not to be resampled and are in the final color space it is
+possible to optimize the handling of alpha by storing the opaque pixels in
+the PNG format (adjusted for the output color space) while storing partially
+opaque pixels in the standard, linear, format. The accuracy required for
+standard alpha composition is relatively low, because the pixels are
+isolated, therefore typically the accuracy loss in storing 8-bit linear
+values is acceptable. (This is not true if the alpha channel is used to
+simulate transparency over large areas - use 16 bits or the PNG mode in
+this case!) This is the 'OPTIMIZED' mode. For this mode a pixel is
+treated as opaque only if the alpha value is equal to the maximum value.
+
+ PNG_ALPHA_STANDARD: The data libpng produces is encoded in the
+standard way assumed by most correctly written graphics software.
+The gamma encoding will be removed by libpng and the
+linear component values will be pre-multiplied by the
+alpha channel.
+
+With this format the final image must be re-encoded to
+match the display gamma before the image is displayed.
+If your system doesn't do that, yet still seems to
+perform arithmetic on the pixels without decoding them,
+it is broken - check out the modes below.
+
+With PNG_ALPHA_STANDARD libpng always produces linear
+component values, whatever screen_gamma you supply. The
+screen_gamma value is, however, used as a default for
+the file gamma if the PNG file has no gamma information.
+
+If you call png_set_gamma() after png_set_alpha_mode() you
+will override the linear encoding. Instead the
+pre-multiplied pixel values will be gamma encoded but
+the alpha channel will still be linear. This may
+actually match the requirements of some broken software,
+but it is unlikely.
+
+While linear 8-bit data is often used it has
+insufficient precision for any image with a reasonable
+dynamic range. To avoid problems, and if your software
+supports it, use png_set_expand_16() to force all
+components to 16 bits.
+
+ PNG_ALPHA_OPTIMIZED: This mode is the same as PNG_ALPHA_STANDARD
+except that completely opaque pixels are gamma encoded according to
+the screen_gamma value. Pixels with alpha less than 1.0
+will still have linear components.
+
+Use this format if you have control over your
+compositing software and so don't do other arithmetic
+(such as scaling) on the data you get from libpng. Your
+compositing software can simply copy opaque pixels to
+the output but still has linear values for the
+non-opaque pixels.
+
+In normal compositing, where the alpha channel encodes
+partial pixel coverage (as opposed to broad area
+translucency), the inaccuracies of the 8-bit
+representation of non-opaque pixels are irrelevant.
+
+You can also try this format if your software is broken;
+it might look better.
+
+ PNG_ALPHA_BROKEN: This is PNG_ALPHA_STANDARD; however, all component
+values, including the alpha channel are gamma encoded. This is
+broken because, in practice, no implementation that uses this choice
+correctly undoes the encoding before handling alpha composition. Use this
+choice only if other serious errors in the software or hardware you use
+mandate it. In most cases of broken software or hardware the bug in the
+final display manifests as a subtle halo around composited parts of the
+image. You may not even perceive this as a halo; the composited part of
+the image may simply appear separate from the background, as though it had
+been cut out of paper and pasted on afterward.
+
+If you don't have to deal with bugs in software or hardware, or if you can fix
+them, there are three recommended ways of using png_set_alpha_mode():
+
+ png_set_alpha_mode(png_ptr, PNG_ALPHA_PNG,
+ screen_gamma);
+
+You can do color correction on the result (libpng does not currently
+support color correction internally). When you handle the alpha channel
+you need to undo the gamma encoding and multiply out the alpha.
+
+ png_set_alpha_mode(png_ptr, PNG_ALPHA_STANDARD,
+ screen_gamma);
+ png_set_expand_16(png_ptr);
+
+If you are using the high level interface, don't call png_set_expand_16();
+instead pass PNG_TRANSFORM_EXPAND_16 to the interface.
+
+With this mode you can't do color correction, but you can do arithmetic,
+including composition and scaling, on the data without further processing.
+
+ png_set_alpha_mode(png_ptr, PNG_ALPHA_OPTIMIZED,
+ screen_gamma);
+
+You can avoid the expansion to 16-bit components with this mode, but you
+lose the ability to scale the image or perform other linear arithmetic.
+All you can do is compose the result onto a matching output. Since this
+mode is libpng-specific you also need to write your own composition
+software.
+
+The following are examples of calls to png_set_alpha_mode to achieve the
+required overall gamma correction and, where necessary, alpha
+premultiplication.
+
+ png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
+
+This is the default libpng handling of the alpha channel - it is not
+pre-multiplied into the color components. In addition the call states
+that the output is for a sRGB system and causes all PNG files without gAMA
+chunks to be assumed to be encoded using sRGB.
+
+ png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
+
+In this case the output is assumed to be something like an sRGB conformant
+display preceeded by a power-law lookup table of power 1.45. This is how
+early Mac systems behaved.
+
+ png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_GAMMA_LINEAR);
+
+This is the classic Jim Blinn approach and will work in academic
+environments where everything is done by the book. It has the shortcoming
+of assuming that input PNG data with no gamma information is linear - this
+is unlikely to be correct unless the PNG files where generated locally.
+Most of the time the output precision will be so low as to show
+significant banding in dark areas of the image.
+
+ png_set_expand_16(pp);
+ png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_DEFAULT_sRGB);
+
+This is a somewhat more realistic Jim Blinn inspired approach. PNG files
+are assumed to have the sRGB encoding if not marked with a gamma value and
+the output is always 16 bits per component. This permits accurate scaling
+and processing of the data. If you know that your input PNG files were
+generated locally you might need to replace PNG_DEFAULT_sRGB with the
+correct value for your system.
+
+ png_set_alpha_mode(pp, PNG_ALPHA_OPTIMIZED, PNG_DEFAULT_sRGB);
+
+If you just need to composite the PNG image onto an existing background
+and if you control the code that does this you can use the optimization
+setting. In this case you just copy completely opaque pixels to the
+output. For pixels that are not completely transparent (you just skip
+those) you do the composition math using png_composite or png_composite_16
+below then encode the resultant 8-bit or 16-bit values to match the output
+encoding.
+
+ Other cases
+
+If neither the PNG nor the standard linear encoding work for you because
+of the software or hardware you use then you have a big problem. The PNG
+case will probably result in halos around the image. The linear encoding
+will probably result in a washed out, too bright, image (it's actually too
+contrasty.) Try the ALPHA_OPTIMIZED mode above - this will probably
+substantially reduce the halos. Alternatively try:
+
+ png_set_alpha_mode(pp, PNG_ALPHA_BROKEN, PNG_DEFAULT_sRGB);
+
+This option will also reduce the halos, but there will be slight dark
+halos round the opaque parts of the image where the background is light.
+In the OPTIMIZED mode the halos will be light halos where the background
+is dark. Take your pick - the halos are unavoidable unless you can get
+your hardware/software fixed! (The OPTIMIZED approach is slightly
+faster.)
+
+When the default gamma of PNG files doesn't match the output gamma.
+If you have PNG files with no gamma information png_set_alpha_mode allows
+you to provide a default gamma, but it also sets the ouput gamma to the
+matching value. If you know your PNG files have a gamma that doesn't
+match the output you can take advantage of the fact that
+png_set_alpha_mode always sets the output gamma but only sets the PNG
+default if it is not already set:
+
+ png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
+ png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
+
+The first call sets both the default and the output gamma values, the
+second call overrides the output gamma without changing the default. This
+is easier than achieving the same effect with png_set_gamma. You must use
+PNG_ALPHA_PNG for the first call - internal checking in png_set_alpha will
+fire if more than one call to png_set_alpha_mode and png_set_background is
+made in the same read operation, however multiple calls with PNG_ALPHA_PNG
+are ignored.
+
+If you don't need, or can't handle, the alpha channel you can call
+png_set_background() to remove it by compositing against a fixed color. Don't
+call png_set_strip_alpha() to do this - it will leave spurious pixel values in
+transparent parts of this image.
+
+ png_set_background(png_ptr, &background_color,
+ PNG_BACKGROUND_GAMMA_SCREEN, 0, 1);
+
+The background_color is an RGB or grayscale value according to the data format
+libpng will produce for you. Because you don't yet know the format of the PNG
+file, if you call png_set_background at this point you must arrange for the
+format produced by libpng to always have 8-bit or 16-bit components and then
+store the color as an 8-bit or 16-bit color as appropriate. The color contains
+separate gray and RGB component values, so you can let libpng produce gray or
+RGB output according to the input format, but low bit depth grayscale images
+must always be converted to at least 8-bit format. (Even though low bit depth
+grayscale images can't have an alpha channel they can have a transparent
+color!)
+
+You set the transforms you need later, either as flags to the high level
+interface or libpng API calls for the low level interface. For reference the
+settings and API calls required are:
+
+8-bit values:
+ PNG_TRANSFORM_SCALE_16 | PNG_EXPAND
+ png_set_expand(png_ptr); png_set_scale_16(png_ptr);
+
+ If you must get exactly the same inaccurate results
+ produced by default in versions prior to libpng-1.5.4,
+ use PNG_TRANSFORM_STRIP_16 and png_set_strip_16(png_ptr)
+ instead.
+
+16-bit values:
+ PNG_TRANSFORM_EXPAND_16
+ png_set_expand_16(png_ptr);
+
+In either case palette image data will be expanded to RGB. If you just want
+color data you can add PNG_TRANSFORM_GRAY_TO_RGB or png_set_gray_to_rgb(png_ptr)
+to the list.
+
+Calling png_set_background before the PNG file header is read will not work
+prior to libpng-1.5.4. Because the failure may result in unexpected warnings or
+errors it is therefore much safer to call png_set_background after the head has
+been read. Unfortunately this means that prior to libpng-1.5.4 it cannot be
+used with the high level interface.
+
+The high-level read interface
+
+At this point there are two ways to proceed; through the high-level
+read interface, or through a sequence of low-level read operations.
+You can use the high-level interface if (a) you are willing to read
+the entire image into memory, and (b) the input transformations
+you want to do are limited to the following set:
+
+ PNG_TRANSFORM_IDENTITY No transformation
+ PNG_TRANSFORM_SCALE_16 Strip 16-bit samples to
+ 8-bit accurately
+ PNG_TRANSFORM_STRIP_16 Chop 16-bit samples to
+ 8-bit less accurately
+ PNG_TRANSFORM_STRIP_ALPHA Discard the alpha channel
+ PNG_TRANSFORM_PACKING Expand 1, 2 and 4-bit
+ samples to bytes
+ PNG_TRANSFORM_PACKSWAP Change order of packed
+ pixels to LSB first
+ PNG_TRANSFORM_EXPAND Perform set_expand()
+ PNG_TRANSFORM_INVERT_MONO Invert monochrome images
+ PNG_TRANSFORM_SHIFT Normalize pixels to the
+ sBIT depth
+ PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA
+ to BGRA
+ PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
+ to AG
+ PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
+ to transparency
+ PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
+ PNG_TRANSFORM_GRAY_TO_RGB Expand grayscale samples
+ to RGB (or GA to RGBA)
+ PNG_TRANSFORM_EXPAND_16 Expand samples to 16 bits
+
+(This excludes setting a background color, doing gamma transformation,
+quantizing, and setting filler.) If this is the case, simply do this:
+
+ png_read_png(png_ptr, info_ptr, png_transforms, NULL)
+
+where png_transforms is an integer containing the bitwise OR of some
+set of transformation flags. This call is equivalent to png_read_info(),
+followed the set of transformations indicated by the transform mask,
+then png_read_image(), and finally png_read_end().
+
+(The final parameter of this call is not yet used. Someday it might point
+to transformation parameters required by some future input transform.)
+
+You must use png_transforms and not call any png_set_transform() functions
+when you use png_read_png().
+
+After you have called png_read_png(), you can retrieve the image data
+with
+
+ row_pointers = png_get_rows(png_ptr, info_ptr);
+
+where row_pointers is an array of pointers to the pixel data for each row:
+
+ png_bytep row_pointers[height];
+
+If you know your image size and pixel size ahead of time, you can allocate
+row_pointers prior to calling png_read_png() with
+
+ if (height > PNG_UINT_32_MAX/(sizeof (png_byte)))
+ png_error (png_ptr,
+ "Image is too tall to process in memory");
+
+ if (width > PNG_UINT_32_MAX/pixel_size)
+ png_error (png_ptr,
+ "Image is too wide to process in memory");
+
+ row_pointers = png_malloc(png_ptr,
+ height*(sizeof (png_bytep)));
+
+ for (int i=0; i<height, i++)
+ row_pointers[i]=NULL; /* security precaution */
+
+ for (int i=0; i<height, i++)
+ row_pointers[i]=png_malloc(png_ptr,
+ width*pixel_size);
+
+ png_set_rows(png_ptr, info_ptr, &row_pointers);
+
+Alternatively you could allocate your image in one big block and define
+row_pointers[i] to point into the proper places in your block.
+
+If you use png_set_rows(), the application is responsible for freeing
+row_pointers (and row_pointers[i], if they were separately allocated).
+
+If you don't allocate row_pointers ahead of time, png_read_png() will
+do it, and it'll be free'ed by libpng when you call png_destroy_*().
+
+The low-level read interface
+
+If you are going the low-level route, you are now ready to read all
+the file information up to the actual image data. You do this with a
+call to png_read_info().
+
+ png_read_info(png_ptr, info_ptr);
+
+This will process all chunks up to but not including the image data.
+
+This also copies some of the data from the PNG file into the decode structure
+for use in later transformations. Important information copied in is:
+
+1) The PNG file gamma from the gAMA chunk. This overwrites the default value
+provided by an earlier call to png_set_gamma or png_set_alpha_mode.
+
+2) Prior to libpng-1.5.4 the background color from a bKGd chunk. This
+damages the information provided by an earlier call to png_set_background
+resulting in unexpected behavior. Libpng-1.5.4 no longer does this.
+
+3) The number of significant bits in each component value. Libpng uses this to
+optimize gamma handling by reducing the internal lookup table sizes.
+
+4) The transparent color information from a tRNS chunk. This can be modified by
+a later call to png_set_tRNS.
+
+Querying the info structure
+
+Functions are used to get the information from the info_ptr once it
+has been read. Note that these fields may not be completely filled
+in until png_read_end() has read the chunk data following the image.
+
+ png_get_IHDR(png_ptr, info_ptr, &width, &height,
+ &bit_depth, &color_type, &interlace_type,
+ &compression_type, &filter_method);
+
+ width - holds the width of the image
+ in pixels (up to 2^31).
+
+ height - holds the height of the image
+ in pixels (up to 2^31).
+
+ bit_depth - holds the bit depth of one of the
+ image channels. (valid values are
+ 1, 2, 4, 8, 16 and depend also on
+ the color_type. See also
+ significant bits (sBIT) below).
+
+ color_type - describes which color/alpha channels
+ are present.
+ PNG_COLOR_TYPE_GRAY
+ (bit depths 1, 2, 4, 8, 16)
+ PNG_COLOR_TYPE_GRAY_ALPHA
+ (bit depths 8, 16)
+ PNG_COLOR_TYPE_PALETTE
+ (bit depths 1, 2, 4, 8)
+ PNG_COLOR_TYPE_RGB
+ (bit_depths 8, 16)
+ PNG_COLOR_TYPE_RGB_ALPHA
+ (bit_depths 8, 16)
+
+ PNG_COLOR_MASK_PALETTE
+ PNG_COLOR_MASK_COLOR
+ PNG_COLOR_MASK_ALPHA
+
+ interlace_type - (PNG_INTERLACE_NONE or
+ PNG_INTERLACE_ADAM7)
+
+ compression_type - (must be PNG_COMPRESSION_TYPE_BASE
+ for PNG 1.0)
+
+ filter_method - (must be PNG_FILTER_TYPE_BASE
+ for PNG 1.0, and can also be
+ PNG_INTRAPIXEL_DIFFERENCING if
+ the PNG datastream is embedded in
+ a MNG-1.0 datastream)
+
+ Any of width, height, color_type, bit_depth,
+ interlace_type, compression_type, or filter_method can
+ be NULL if you are not interested in their values.
+
+ Note that png_get_IHDR() returns 32-bit data into
+ the application's width and height variables.
+ This is an unsafe situation if these are not png_uint_32
+ variables. In such situations, the
+ png_get_image_width() and png_get_image_height()
+ functions described below are safer.
+
+ width = png_get_image_width(png_ptr,
+ info_ptr);
+
+ height = png_get_image_height(png_ptr,
+ info_ptr);
+
+ bit_depth = png_get_bit_depth(png_ptr,
+ info_ptr);
+
+ color_type = png_get_color_type(png_ptr,
+ info_ptr);
+
+ interlace_type = png_get_interlace_type(png_ptr,
+ info_ptr);
+
+ compression_type = png_get_compression_type(png_ptr,
+ info_ptr);
+
+ filter_method = png_get_filter_type(png_ptr,
+ info_ptr);
+
+ channels = png_get_channels(png_ptr, info_ptr);
+
+ channels - number of channels of info for the
+ color type (valid values are 1 (GRAY,
+ PALETTE), 2 (GRAY_ALPHA), 3 (RGB),
+ 4 (RGB_ALPHA or RGB + filler byte))
+
+ rowbytes = png_get_rowbytes(png_ptr, info_ptr);
+
+ rowbytes - number of bytes needed to hold a row
+
+ signature = png_get_signature(png_ptr, info_ptr);
+
+ signature - holds the signature read from the
+ file (if any). The data is kept in
+ the same offset it would be if the
+ whole signature were read (i.e. if an
+ application had already read in 4
+ bytes of signature before starting
+ libpng, the remaining 4 bytes would
+ be in signature[4] through signature[7]
+ (see png_set_sig_bytes())).
+
+These are also important, but their validity depends on whether the chunk
+has been read. The png_get_valid(png_ptr, info_ptr, PNG_INFO_<chunk>) and
+png_get_<chunk>(png_ptr, info_ptr, ...) functions return non-zero if the
+data has been read, or zero if it is missing. The parameters to the
+png_get_<chunk> are set directly if they are simple data types, or a
+pointer into the info_ptr is returned for any complex types.
+
+The colorspace data from gAMA, cHRM, sRGB, iCCP, and sBIT chunks
+is simply returned to give the application information about how the
+image was encoded. Libpng itself only does transformations using the file
+gamma when combining semitransparent pixels with the background color, and,
+since libpng-1.6.0, when converting between 8-bit sRGB and 16-bit linear pixels
+within the simplified API. Libpng also uses the file gamma when converting
+RGB to gray, beginning with libpng-1.0.5, if the application calls
+png_set_rgb_to_gray()).
+
+ png_get_PLTE(png_ptr, info_ptr, &palette,
+ &num_palette);
+
+ palette - the palette for the file
+ (array of png_color)
+
+ num_palette - number of entries in the palette
+
+ png_get_gAMA(png_ptr, info_ptr, &file_gamma);
+ png_get_gAMA_fixed(png_ptr, info_ptr, &int_file_gamma);
+
+ file_gamma - the gamma at which the file is
+ written (PNG_INFO_gAMA)
+
+ int_file_gamma - 100,000 times the gamma at which the
+ file is written
+
+ png_get_cHRM(png_ptr, info_ptr, &white_x, &white_y, &red_x,
+ &red_y, &green_x, &green_y, &blue_x, &blue_y)
+ png_get_cHRM_XYZ(png_ptr, info_ptr, &red_X, &red_Y, &red_Z,
+ &green_X, &green_Y, &green_Z, &blue_X, &blue_Y,
+ &blue_Z)
+ png_get_cHRM_fixed(png_ptr, info_ptr, &int_white_x,
+ &int_white_y, &int_red_x, &int_red_y,
+ &int_green_x, &int_green_y, &int_blue_x,
+ &int_blue_y)
+ png_get_cHRM_XYZ_fixed(png_ptr, info_ptr, &int_red_X, &int_red_Y,
+ &int_red_Z, &int_green_X, &int_green_Y,
+ &int_green_Z, &int_blue_X, &int_blue_Y,
+ &int_blue_Z)
+
+ {white,red,green,blue}_{x,y}
+ A color space encoding specified using the
+ chromaticities of the end points and the
+ white point. (PNG_INFO_cHRM)
+
+ {red,green,blue}_{X,Y,Z}
+ A color space encoding specified using the
+ encoding end points - the CIE tristimulus
+ specification of the intended color of the red,
+ green and blue channels in the PNG RGB data.
+ The white point is simply the sum of the three
+ end points. (PNG_INFO_cHRM)
+
+ png_get_sRGB(png_ptr, info_ptr, &srgb_intent);
+
+ srgb_intent - the rendering intent (PNG_INFO_sRGB)
+ The presence of the sRGB chunk
+ means that the pixel data is in the
+ sRGB color space. This chunk also
+ implies specific values of gAMA and
+ cHRM.
+
+ png_get_iCCP(png_ptr, info_ptr, &name,
+ &compression_type, &profile, &proflen);
+
+ name - The profile name.
+
+ compression_type - The compression type; always
+ PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
+ You may give NULL to this argument to
+ ignore it.
+
+ profile - International Color Consortium color
+ profile data. May contain NULs.
+
+ proflen - length of profile data in bytes.
+
+ png_get_sBIT(png_ptr, info_ptr, &sig_bit);
+
+ sig_bit - the number of significant bits for
+ (PNG_INFO_sBIT) each of the gray,
+ red, green, and blue channels,
+ whichever are appropriate for the
+ given color type (png_color_16)
+
+ png_get_tRNS(png_ptr, info_ptr, &trans_alpha,
+ &num_trans, &trans_color);
+
+ trans_alpha - array of alpha (transparency)
+ entries for palette (PNG_INFO_tRNS)
+
+ num_trans - number of transparent entries
+ (PNG_INFO_tRNS)
+
+ trans_color - graylevel or color sample values of
+ the single transparent color for
+ non-paletted images (PNG_INFO_tRNS)
+
+ png_get_hIST(png_ptr, info_ptr, &hist);
+ (PNG_INFO_hIST)
+
+ hist - histogram of palette (array of
+ png_uint_16)
+
+ png_get_tIME(png_ptr, info_ptr, &mod_time);
+
+ mod_time - time image was last modified
+ (PNG_VALID_tIME)
+
+ png_get_bKGD(png_ptr, info_ptr, &background);
+
+ background - background color (of type
+ png_color_16p) (PNG_VALID_bKGD)
+ valid 16-bit red, green and blue
+ values, regardless of color_type
+
+ num_comments = png_get_text(png_ptr, info_ptr,
+ &text_ptr, &num_text);
+
+ num_comments - number of comments
+
+ text_ptr - array of png_text holding image
+ comments
+
+ text_ptr[i].compression - type of compression used
+ on "text" PNG_TEXT_COMPRESSION_NONE
+ PNG_TEXT_COMPRESSION_zTXt
+ PNG_ITXT_COMPRESSION_NONE
+ PNG_ITXT_COMPRESSION_zTXt
+
+ text_ptr[i].key - keyword for comment. Must contain
+ 1-79 characters.
+
+ text_ptr[i].text - text comments for current
+ keyword. Can be empty.
+
+ text_ptr[i].text_length - length of text string,
+ after decompression, 0 for iTXt
+
+ text_ptr[i].itxt_length - length of itxt string,
+ after decompression, 0 for tEXt/zTXt
+
+ text_ptr[i].lang - language of comment (empty
+ string for unknown).
+
+ text_ptr[i].lang_key - keyword in UTF-8
+ (empty string for unknown).
+
+ Note that the itxt_length, lang, and lang_key
+ members of the text_ptr structure only exist when the
+ library is built with iTXt chunk support. Prior to
+ libpng-1.4.0 the library was built by default without
+ iTXt support. Also note that when iTXt is supported,
+ they contain NULL pointers when the "compression"
+ field contains PNG_TEXT_COMPRESSION_NONE or
+ PNG_TEXT_COMPRESSION_zTXt.
+
+ num_text - number of comments (same as
+ num_comments; you can put NULL here
+ to avoid the duplication)
+
+ Note while png_set_text() will accept text, language,
+ and translated keywords that can be NULL pointers, the
+ structure returned by png_get_text will always contain
+ regular zero-terminated C strings. They might be
+ empty strings but they will never be NULL pointers.
+
+ num_spalettes = png_get_sPLT(png_ptr, info_ptr,
+ &palette_ptr);
+
+ num_spalettes - number of sPLT chunks read.
+
+ palette_ptr - array of palette structures holding
+ contents of one or more sPLT chunks
+ read.
+
+ png_get_oFFs(png_ptr, info_ptr, &offset_x, &offset_y,
+ &unit_type);
+
+ offset_x - positive offset from the left edge
+ of the screen (can be negative)
+
+ offset_y - positive offset from the top edge
+ of the screen (can be negative)
+
+ unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
+
+ png_get_pHYs(png_ptr, info_ptr, &res_x, &res_y,
+ &unit_type);
+
+ res_x - pixels/unit physical resolution in
+ x direction
+
+ res_y - pixels/unit physical resolution in
+ x direction
+
+ unit_type - PNG_RESOLUTION_UNKNOWN,
+ PNG_RESOLUTION_METER
+
+ png_get_sCAL(png_ptr, info_ptr, &unit, &width,
+ &height)
+
+ unit - physical scale units (an integer)
+
+ width - width of a pixel in physical scale units
+
+ height - height of a pixel in physical scale units
+ (width and height are doubles)
+
+ png_get_sCAL_s(png_ptr, info_ptr, &unit, &width,
+ &height)
+
+ unit - physical scale units (an integer)
+
+ width - width of a pixel in physical scale units
+ (expressed as a string)
+
+ height - height of a pixel in physical scale units
+ (width and height are strings like "2.54")
+
+ num_unknown_chunks = png_get_unknown_chunks(png_ptr,
+ info_ptr, &unknowns)
+
+ unknowns - array of png_unknown_chunk
+ structures holding unknown chunks
+
+ unknowns[i].name - name of unknown chunk
+
+ unknowns[i].data - data of unknown chunk
+
+ unknowns[i].size - size of unknown chunk's data
+
+ unknowns[i].location - position of chunk in file
+
+ The value of "i" corresponds to the order in which the
+ chunks were read from the PNG file or inserted with the
+ png_set_unknown_chunks() function.
+
+ The value of "location" is a bitwise "or" of
+
+ PNG_HAVE_IHDR (0x01)
+ PNG_HAVE_PLTE (0x02)
+ PNG_AFTER_IDAT (0x08)
+
+The data from the pHYs chunk can be retrieved in several convenient
+forms:
+
+ res_x = png_get_x_pixels_per_meter(png_ptr,
+ info_ptr)
+
+ res_y = png_get_y_pixels_per_meter(png_ptr,
+ info_ptr)
+
+ res_x_and_y = png_get_pixels_per_meter(png_ptr,
+ info_ptr)
+
+ res_x = png_get_x_pixels_per_inch(png_ptr,
+ info_ptr)
+
+ res_y = png_get_y_pixels_per_inch(png_ptr,
+ info_ptr)
+
+ res_x_and_y = png_get_pixels_per_inch(png_ptr,
+ info_ptr)
+
+ aspect_ratio = png_get_pixel_aspect_ratio(png_ptr,
+ info_ptr)
+
+ Each of these returns 0 [signifying "unknown"] if
+ the data is not present or if res_x is 0;
+ res_x_and_y is 0 if res_x != res_y
+
+ Note that because of the way the resolutions are
+ stored internally, the inch conversions won't
+ come out to exactly even number. For example,
+ 72 dpi is stored as 0.28346 pixels/meter, and
+ when this is retrieved it is 71.9988 dpi, so
+ be sure to round the returned value appropriately
+ if you want to display a reasonable-looking result.
+
+The data from the oFFs chunk can be retrieved in several convenient
+forms:
+
+ x_offset = png_get_x_offset_microns(png_ptr, info_ptr);
+
+ y_offset = png_get_y_offset_microns(png_ptr, info_ptr);
+
+ x_offset = png_get_x_offset_inches(png_ptr, info_ptr);
+
+ y_offset = png_get_y_offset_inches(png_ptr, info_ptr);
+
+ Each of these returns 0 [signifying "unknown" if both
+ x and y are 0] if the data is not present or if the
+ chunk is present but the unit is the pixel. The
+ remark about inexact inch conversions applies here
+ as well, because a value in inches can't always be
+ converted to microns and back without some loss
+ of precision.
+
+For more information, see the
+PNG specification for chunk contents. Be careful with trusting
+rowbytes, as some of the transformations could increase the space
+needed to hold a row (expand, filler, gray_to_rgb, etc.).
+See png_read_update_info(), below.
+
+A quick word about text_ptr and num_text. PNG stores comments in
+keyword/text pairs, one pair per chunk, with no limit on the number
+of text chunks, and a 2^31 byte limit on their size. While there are
+suggested keywords, there is no requirement to restrict the use to these
+strings. It is strongly suggested that keywords and text be sensible
+to humans (that's the point), so don't use abbreviations. Non-printing
+symbols are not allowed. See the PNG specification for more details.
+There is also no requirement to have text after the keyword.
+
+Keywords should be limited to 79 Latin-1 characters without leading or
+trailing spaces, but non-consecutive spaces are allowed within the
+keyword. It is possible to have the same keyword any number of times.
+The text_ptr is an array of png_text structures, each holding a
+pointer to a language string, a pointer to a keyword and a pointer to
+a text string. The text string, language code, and translated
+keyword may be empty or NULL pointers. The keyword/text
+pairs are put into the array in the order that they are received.
+However, some or all of the text chunks may be after the image, so, to
+make sure you have read all the text chunks, don't mess with these
+until after you read the stuff after the image. This will be
+mentioned again below in the discussion that goes with png_read_end().
+
+Input transformations
+
+After you've read the header information, you can set up the library
+to handle any special transformations of the image data. The various
+ways to transform the data will be described in the order that they
+should occur. This is important, as some of these change the color
+type and/or bit depth of the data, and some others only work on
+certain color types and bit depths.
+
+Transformations you request are ignored if they don't have any meaning for a
+particular input data format. However some transformations can have an effect
+as a result of a previous transformation. If you specify a contradictory set of
+transformations, for example both adding and removing the alpha channel, you
+cannot predict the final result.
+
+The color used for the transparency values should be supplied in the same
+format/depth as the current image data. It is stored in the same format/depth
+as the image data in a tRNS chunk, so this is what libpng expects for this data.
+
+The color used for the background value depends on the need_expand argument as
+described below.
+
+Data will be decoded into the supplied row buffers packed into bytes
+unless the library has been told to transform it into another format.
+For example, 4 bit/pixel paletted or grayscale data will be returned
+2 pixels/byte with the leftmost pixel in the high-order bits of the byte,
+unless png_set_packing() is called. 8-bit RGB data will be stored
+in RGB RGB RGB format unless png_set_filler() or png_set_add_alpha()
+is called to insert filler bytes, either before or after each RGB triplet.
+
+16-bit RGB data will be returned RRGGBB RRGGBB, with the most significant
+byte of the color value first, unless png_set_scale_16() is called to
+transform it to regular RGB RGB triplets, or png_set_filler() or
+png_set_add alpha() is called to insert two filler bytes, either before
+or after each RRGGBB triplet. Similarly, 8-bit or 16-bit grayscale data can
+be modified with png_set_filler(), png_set_add_alpha(), png_set_strip_16(),
+or png_set_scale_16().
+
+The following code transforms grayscale images of less than 8 to 8 bits,
+changes paletted images to RGB, and adds a full alpha channel if there is
+transparency information in a tRNS chunk. This is most useful on
+grayscale images with bit depths of 2 or 4 or if there is a multiple-image
+viewing application that wishes to treat all images in the same way.
+
+ if (color_type == PNG_COLOR_TYPE_PALETTE)
+ png_set_palette_to_rgb(png_ptr);
+
+ if (png_get_valid(png_ptr, info_ptr,
+ PNG_INFO_tRNS)) png_set_tRNS_to_alpha(png_ptr);
+
+ if (color_type == PNG_COLOR_TYPE_GRAY &&
+ bit_depth < 8) png_set_expand_gray_1_2_4_to_8(png_ptr);
+
+The first two functions are actually aliases for png_set_expand(), added
+in libpng version 1.0.4, with the function names expanded to improve code
+readability. In some future version they may actually do different
+things.
+
+As of libpng version 1.2.9, png_set_expand_gray_1_2_4_to_8() was
+added. It expands the sample depth without changing tRNS to alpha.
+
+As of libpng version 1.5.2, png_set_expand_16() was added. It behaves as
+png_set_expand(); however, the resultant channels have 16 bits rather than 8.
+Use this when the output color or gray channels are made linear to avoid fairly
+severe accuracy loss.
+
+ if (bit_depth < 16)
+ png_set_expand_16(png_ptr);
+
+PNG can have files with 16 bits per channel. If you only can handle
+8 bits per channel, this will strip the pixels down to 8-bit.
+
+ if (bit_depth == 16)
+#if PNG_LIBPNG_VER >= 10504
+ png_set_scale_16(png_ptr);
+#else
+ png_set_strip_16(png_ptr);
+#endif
+
+(The more accurate "png_set_scale_16()" API became available in libpng version
+1.5.4).
+
+If you need to process the alpha channel on the image separately from the image
+data (for example if you convert it to a bitmap mask) it is possible to have
+libpng strip the channel leaving just RGB or gray data:
+
+ if (color_type & PNG_COLOR_MASK_ALPHA)
+ png_set_strip_alpha(png_ptr);
+
+If you strip the alpha channel you need to find some other way of dealing with
+the information. If, instead, you want to convert the image to an opaque
+version with no alpha channel use png_set_background; see below.
+
+As of libpng version 1.5.2, almost all useful expansions are supported, the
+major ommissions are conversion of grayscale to indexed images (which can be
+done trivially in the application) and conversion of indexed to grayscale (which
+can be done by a trivial manipulation of the palette.)
+
+In the following table, the 01 means grayscale with depth<8, 31 means
+indexed with depth<8, other numerals represent the color type, "T" means
+the tRNS chunk is present, A means an alpha channel is present, and O
+means tRNS or alpha is present but all pixels in the image are opaque.
+
+ FROM 01 31 0 0T 0O 2 2T 2O 3 3T 3O 4A 4O 6A 6O
+ TO
+ 01 - [G] - - - - - - - - - - - - -
+ 31 [Q] Q [Q] [Q] [Q] Q Q Q Q Q Q [Q] [Q] Q Q
+ 0 1 G + . . G G G G G G B B GB GB
+ 0T lt Gt t + . Gt G G Gt G G Bt Bt GBt GBt
+ 0O lt Gt t . + Gt Gt G Gt Gt G Bt Bt GBt GBt
+ 2 C P C C C + . . C - - CB CB B B
+ 2T Ct - Ct C C t + t - - - CBt CBt Bt Bt
+ 2O Ct - Ct C C t t + - - - CBt CBt Bt Bt
+ 3 [Q] p [Q] [Q] [Q] Q Q Q + . . [Q] [Q] Q Q
+ 3T [Qt] p [Qt][Q] [Q] Qt Qt Qt t + t [Qt][Qt] Qt Qt
+ 3O [Qt] p [Qt][Q] [Q] Qt Qt Qt t t + [Qt][Qt] Qt Qt
+ 4A lA G A T T GA GT GT GA GT GT + BA G GBA
+ 4O lA GBA A T T GA GT GT GA GT GT BA + GBA G
+ 6A CA PA CA C C A T tT PA P P C CBA + BA
+ 6O CA PBA CA C C A tT T PA P P CBA C BA +
+
+Within the matrix,
+ "+" identifies entries where 'from' and 'to' are the same.
+ "-" means the transformation is not supported.
+ "." means nothing is necessary (a tRNS chunk can just be ignored).
+ "t" means the transformation is obtained by png_set_tRNS.
+ "A" means the transformation is obtained by png_set_add_alpha().
+ "X" means the transformation is obtained by png_set_expand().
+ "1" means the transformation is obtained by
+ png_set_expand_gray_1_2_4_to_8() (and by png_set_expand()
+ if there is no transparency in the original or the final
+ format).
+ "C" means the transformation is obtained by png_set_gray_to_rgb().
+ "G" means the transformation is obtained by png_set_rgb_to_gray().
+ "P" means the transformation is obtained by
+ png_set_expand_palette_to_rgb().
+ "p" means the transformation is obtained by png_set_packing().
+ "Q" means the transformation is obtained by png_set_quantize().
+ "T" means the transformation is obtained by
+ png_set_tRNS_to_alpha().
+ "B" means the transformation is obtained by
+ png_set_background(), or png_strip_alpha().
+
+When an entry has multiple transforms listed all are required to cause the
+right overall transformation. When two transforms are separated by a comma
+either will do the job. When transforms are enclosed in [] the transform should
+do the job but this is currently unimplemented - a different format will result
+if the suggested transformations are used.
+
+In PNG files, the alpha channel in an image
+is the level of opacity. If you need the alpha channel in an image to
+be the level of transparency instead of opacity, you can invert the
+alpha channel (or the tRNS chunk data) after it's read, so that 0 is
+fully opaque and 255 (in 8-bit or paletted images) or 65535 (in 16-bit
+images) is fully transparent, with
+
+ png_set_invert_alpha(png_ptr);
+
+PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
+they can, resulting in, for example, 8 pixels per byte for 1 bit
+files. This code expands to 1 pixel per byte without changing the
+values of the pixels:
+
+ if (bit_depth < 8)
+ png_set_packing(png_ptr);
+
+PNG files have possible bit depths of 1, 2, 4, 8, and 16. All pixels
+stored in a PNG image have been "scaled" or "shifted" up to the next
+higher possible bit depth (e.g. from 5 bits/sample in the range [0,31]
+to 8 bits/sample in the range [0, 255]). However, it is also possible
+to convert the PNG pixel data back to the original bit depth of the
+image. This call reduces the pixels back down to the original bit depth:
+
+ png_color_8p sig_bit;
+
+ if (png_get_sBIT(png_ptr, info_ptr, &sig_bit))
+ png_set_shift(png_ptr, sig_bit);
+
+PNG files store 3-color pixels in red, green, blue order. This code
+changes the storage of the pixels to blue, green, red:
+
+ if (color_type == PNG_COLOR_TYPE_RGB ||
+ color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+ png_set_bgr(png_ptr);
+
+PNG files store RGB pixels packed into 3 or 6 bytes. This code expands them
+into 4 or 8 bytes for windowing systems that need them in this format:
+
+ if (color_type == PNG_COLOR_TYPE_RGB)
+ png_set_filler(png_ptr, filler, PNG_FILLER_BEFORE);
+
+where "filler" is the 8-bit or 16-bit number to fill with, and the location
+is either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether
+you want the filler before the RGB or after. When filling an 8-bit pixel,
+the least significant 8 bits of the number are used, if a 16-bit number is
+supplied. This transformation does not affect images that already have full
+alpha channels. To add an opaque alpha channel, use filler=0xffff and
+PNG_FILLER_AFTER which will generate RGBA pixels.
+
+Note that png_set_filler() does not change the color type. If you want
+to do that, you can add a true alpha channel with
+
+ if (color_type == PNG_COLOR_TYPE_RGB ||
+ color_type == PNG_COLOR_TYPE_GRAY)
+ png_set_add_alpha(png_ptr, filler, PNG_FILLER_AFTER);
+
+where "filler" contains the alpha value to assign to each pixel.
+The png_set_add_alpha() function was added in libpng-1.2.7.
+
+If you are reading an image with an alpha channel, and you need the
+data as ARGB instead of the normal PNG format RGBA:
+
+ if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+ png_set_swap_alpha(png_ptr);
+
+For some uses, you may want a grayscale image to be represented as
+RGB. This code will do that conversion:
+
+ if (color_type == PNG_COLOR_TYPE_GRAY ||
+ color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+ png_set_gray_to_rgb(png_ptr);
+
+Conversely, you can convert an RGB or RGBA image to grayscale or grayscale
+with alpha.
+
+ if (color_type == PNG_COLOR_TYPE_RGB ||
+ color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+ png_set_rgb_to_gray(png_ptr, error_action,
+ double red_weight, double green_weight);
+
+ error_action = 1: silently do the conversion
+
+ error_action = 2: issue a warning if the original
+ image has any pixel where
+ red != green or red != blue
+
+ error_action = 3: issue an error and abort the
+ conversion if the original
+ image has any pixel where
+ red != green or red != blue
+
+ red_weight: weight of red component
+
+ green_weight: weight of green component
+ If either weight is negative, default
+ weights are used.
+
+In the corresponding fixed point API the red_weight and green_weight values are
+simply scaled by 100,000:
+
+ png_set_rgb_to_gray(png_ptr, error_action,
+ png_fixed_point red_weight,
+ png_fixed_point green_weight);
+
+If you have set error_action = 1 or 2, you can
+later check whether the image really was gray, after processing
+the image rows, with the png_get_rgb_to_gray_status(png_ptr) function.
+It will return a png_byte that is zero if the image was gray or
+1 if there were any non-gray pixels. Background and sBIT data
+will be silently converted to grayscale, using the green channel
+data for sBIT, regardless of the error_action setting.
+
+The default values come from the PNG file cHRM chunk if present; otherwise, the
+defaults correspond to the ITU-R recommendation 709, and also the sRGB color
+space, as recommended in the Charles Poynton's Colour FAQ,
+Copyright (c) 2006-11-28 Charles Poynton, in section 9:
+
+<http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html#RTFToC9>
+
+ Y = 0.2126 * R + 0.7152 * G + 0.0722 * B
+
+Previous versions of this document, 1998 through 2002, recommended a slightly
+different formula:
+
+ Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
+
+Libpng uses an integer approximation:
+
+ Y = (6968 * R + 23434 * G + 2366 * B)/32768
+
+The calculation is done in a linear colorspace, if the image gamma
+can be determined.
+
+The png_set_background() function has been described already; it tells libpng to
+composite images with alpha or simple transparency against the supplied
+background color. For compatibility with versions of libpng earlier than
+libpng-1.5.4 it is recommended that you call the function after reading the file
+header, even if you don't want to use the color in a bKGD chunk, if one exists.
+
+If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid),
+you may use this color, or supply another color more suitable for
+the current display (e.g., the background color from a web page). You
+need to tell libpng how the color is represented, both the format of the
+component values in the color (the number of bits) and the gamma encoding of the
+color. The function takes two arguments, background_gamma_mode and need_expand
+to convey this information; however, only two combinations are likely to be
+useful:
+
+ png_color_16 my_background;
+ png_color_16p image_background;
+
+ if (png_get_bKGD(png_ptr, info_ptr, &image_background))
+ png_set_background(png_ptr, image_background,
+ PNG_BACKGROUND_GAMMA_FILE, 1/*needs to be expanded*/, 1);
+ else
+ png_set_background(png_ptr, &my_background,
+ PNG_BACKGROUND_GAMMA_SCREEN, 0/*do not expand*/, 1);
+
+The second call was described above - my_background is in the format of the
+final, display, output produced by libpng. Because you now know the format of
+the PNG it is possible to avoid the need to choose either 8-bit or 16-bit
+output and to retain palette images (the palette colors will be modified
+appropriately and the tRNS chunk removed.) However, if you are doing this,
+take great care not to ask for transformations without checking first that
+they apply!
+
+In the first call the background color has the original bit depth and color type
+of the PNG file. So, for palette images the color is supplied as a palette
+index and for low bit greyscale images the color is a reduced bit value in
+image_background->gray.
+
+If you didn't call png_set_gamma() before reading the file header, for example
+if you need your code to remain compatible with older versions of libpng prior
+to libpng-1.5.4, this is the place to call it.
+
+Do not call it if you called png_set_alpha_mode(); doing so will damage the
+settings put in place by png_set_alpha_mode(). (If png_set_alpha_mode() is
+supported then you can certainly do png_set_gamma() before reading the PNG
+header.)
+
+This API unconditionally sets the screen and file gamma values, so it will
+override the value in the PNG file unless it is called before the PNG file
+reading starts. For this reason you must always call it with the PNG file
+value when you call it in this position:
+
+ if (png_get_gAMA(png_ptr, info_ptr, &file_gamma))
+ png_set_gamma(png_ptr, screen_gamma, file_gamma);
+
+ else
+ png_set_gamma(png_ptr, screen_gamma, 0.45455);
+
+If you need to reduce an RGB file to a paletted file, or if a paletted
+file has more entries than will fit on your screen, png_set_quantize()
+will do that. Note that this is a simple match quantization that merely
+finds the closest color available. This should work fairly well with
+optimized palettes, but fairly badly with linear color cubes. If you
+pass a palette that is larger than maximum_colors, the file will
+reduce the number of colors in the palette so it will fit into
+maximum_colors. If there is a histogram, libpng will use it to make
+more intelligent choices when reducing the palette. If there is no
+histogram, it may not do as good a job.
+
+ if (color_type & PNG_COLOR_MASK_COLOR)
+ {
+ if (png_get_valid(png_ptr, info_ptr,
+ PNG_INFO_PLTE))
+ {
+ png_uint_16p histogram = NULL;
+
+ png_get_hIST(png_ptr, info_ptr,
+ &histogram);
+ png_set_quantize(png_ptr, palette, num_palette,
+ max_screen_colors, histogram, 1);
+ }
+
+ else
+ {
+ png_color std_color_cube[MAX_SCREEN_COLORS] =
+ { ... colors ... };
+
+ png_set_quantize(png_ptr, std_color_cube,
+ MAX_SCREEN_COLORS, MAX_SCREEN_COLORS,
+ NULL,0);
+ }
+ }
+
+PNG files describe monochrome as black being zero and white being one.
+The following code will reverse this (make black be one and white be
+zero):
+
+ if (bit_depth == 1 && color_type == PNG_COLOR_TYPE_GRAY)
+ png_set_invert_mono(png_ptr);
+
+This function can also be used to invert grayscale and gray-alpha images:
+
+ if (color_type == PNG_COLOR_TYPE_GRAY ||
+ color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+ png_set_invert_mono(png_ptr);
+
+PNG files store 16-bit pixels in network byte order (big-endian,
+ie. most significant bits first). This code changes the storage to the
+other way (little-endian, i.e. least significant bits first, the
+way PCs store them):
+
+ if (bit_depth == 16)
+ png_set_swap(png_ptr);
+
+If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
+need to change the order the pixels are packed into bytes, you can use:
+
+ if (bit_depth < 8)
+ png_set_packswap(png_ptr);
+
+Finally, you can write your own transformation function if none of
+the existing ones meets your needs. This is done by setting a callback
+with
+
+ png_set_read_user_transform_fn(png_ptr,
+ read_transform_fn);
+
+You must supply the function
+
+ void read_transform_fn(png_structp png_ptr, png_row_infop
+ row_info, png_bytep data)
+
+See pngtest.c for a working example. Your function will be called
+after all of the other transformations have been processed. Take care with
+interlaced images if you do the interlace yourself - the width of the row is the
+width in 'row_info', not the overall image width.
+
+If supported, libpng provides two information routines that you can use to find
+where you are in processing the image:
+
+ png_get_current_pass_number(png_structp png_ptr);
+ png_get_current_row_number(png_structp png_ptr);
+
+Don't try using these outside a transform callback - firstly they are only
+supported if user transforms are supported, secondly they may well return
+unexpected results unless the row is actually being processed at the moment they
+are called.
+
+With interlaced
+images the value returned is the row in the input sub-image image. Use
+PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
+find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass).
+
+The discussion of interlace handling above contains more information on how to
+use these values.
+
+You can also set up a pointer to a user structure for use by your
+callback function, and you can inform libpng that your transform
+function will change the number of channels or bit depth with the
+function
+
+ png_set_user_transform_info(png_ptr, user_ptr,
+ user_depth, user_channels);
+
+The user's application, not libpng, is responsible for allocating and
+freeing any memory required for the user structure.
+
+You can retrieve the pointer via the function
+png_get_user_transform_ptr(). For example:
+
+ voidp read_user_transform_ptr =
+ png_get_user_transform_ptr(png_ptr);
+
+The last thing to handle is interlacing; this is covered in detail below,
+but you must call the function here if you want libpng to handle expansion
+of the interlaced image.
+
+ number_of_passes = png_set_interlace_handling(png_ptr);
+
+After setting the transformations, libpng can update your png_info
+structure to reflect any transformations you've requested with this
+call.
+
+ png_read_update_info(png_ptr, info_ptr);
+
+This is most useful to update the info structure's rowbytes
+field so you can use it to allocate your image memory. This function
+will also update your palette with the correct screen_gamma and
+background if these have been given with the calls above. You may
+only call png_read_update_info() once with a particular info_ptr.
+
+After you call png_read_update_info(), you can allocate any
+memory you need to hold the image. The row data is simply
+raw byte data for all forms of images. As the actual allocation
+varies among applications, no example will be given. If you
+are allocating one large chunk, you will need to build an
+array of pointers to each row, as it will be needed for some
+of the functions below.
+
+Remember: Before you call png_read_update_info(), the png_get_*()
+functions return the values corresponding to the original PNG image.
+After you call png_read_update_info the values refer to the image
+that libpng will output. Consequently you must call all the png_set_
+functions before you call png_read_update_info(). This is particularly
+important for png_set_interlace_handling() - if you are going to call
+png_read_update_info() you must call png_set_interlace_handling() before
+it unless you want to receive interlaced output.
+
+Reading image data
+
+After you've allocated memory, you can read the image data.
+The simplest way to do this is in one function call. If you are
+allocating enough memory to hold the whole image, you can just
+call png_read_image() and libpng will read in all the image data
+and put it in the memory area supplied. You will need to pass in
+an array of pointers to each row.
+
+This function automatically handles interlacing, so you don't
+need to call png_set_interlace_handling() (unless you call
+png_read_update_info()) or call this function multiple times, or any
+of that other stuff necessary with png_read_rows().
+
+ png_read_image(png_ptr, row_pointers);
+
+where row_pointers is:
+
+ png_bytep row_pointers[height];
+
+You can point to void or char or whatever you use for pixels.
+
+If you don't want to read in the whole image at once, you can
+use png_read_rows() instead. If there is no interlacing (check
+interlace_type == PNG_INTERLACE_NONE), this is simple:
+
+ png_read_rows(png_ptr, row_pointers, NULL,
+ number_of_rows);
+
+where row_pointers is the same as in the png_read_image() call.
+
+If you are doing this just one row at a time, you can do this with
+a single row_pointer instead of an array of row_pointers:
+
+ png_bytep row_pointer = row;
+ png_read_row(png_ptr, row_pointer, NULL);
+
+If the file is interlaced (interlace_type != 0 in the IHDR chunk), things
+get somewhat harder. The only current (PNG Specification version 1.2)
+interlacing type for PNG is (interlace_type == PNG_INTERLACE_ADAM7);
+a somewhat complicated 2D interlace scheme, known as Adam7, that
+breaks down an image into seven smaller images of varying size, based
+on an 8x8 grid. This number is defined (from libpng 1.5) as
+PNG_INTERLACE_ADAM7_PASSES in png.h
+
+libpng can fill out those images or it can give them to you "as is".
+It is almost always better to have libpng handle the interlacing for you.
+If you want the images filled out, there are two ways to do that. The one
+mentioned in the PNG specification is to expand each pixel to cover
+those pixels that have not been read yet (the "rectangle" method).
+This results in a blocky image for the first pass, which gradually
+smooths out as more pixels are read. The other method is the "sparkle"
+method, where pixels are drawn only in their final locations, with the
+rest of the image remaining whatever colors they were initialized to
+before the start of the read. The first method usually looks better,
+but tends to be slower, as there are more pixels to put in the rows.
+
+If, as is likely, you want libpng to expand the images, call this before
+calling png_start_read_image() or png_read_update_info():
+
+ if (interlace_type == PNG_INTERLACE_ADAM7)
+ number_of_passes
+ = png_set_interlace_handling(png_ptr);
+
+This will return the number of passes needed. Currently, this is seven,
+but may change if another interlace type is added. This function can be
+called even if the file is not interlaced, where it will return one pass.
+You then need to read the whole image 'number_of_passes' times. Each time
+will distribute the pixels from the current pass to the correct place in
+the output image, so you need to supply the same rows to png_read_rows in
+each pass.
+
+If you are not going to display the image after each pass, but are
+going to wait until the entire image is read in, use the sparkle
+effect. This effect is faster and the end result of either method
+is exactly the same. If you are planning on displaying the image
+after each pass, the "rectangle" effect is generally considered the
+better looking one.
+
+If you only want the "sparkle" effect, just call png_read_rows() as
+normal, with the third parameter NULL. Make sure you make pass over
+the image number_of_passes times, and you don't change the data in the
+rows between calls. You can change the locations of the data, just
+not the data. Each pass only writes the pixels appropriate for that
+pass, and assumes the data from previous passes is still valid.
+
+ png_read_rows(png_ptr, row_pointers, NULL,
+ number_of_rows);
+
+If you only want the first effect (the rectangles), do the same as
+before except pass the row buffer in the third parameter, and leave
+the second parameter NULL.
+
+ png_read_rows(png_ptr, NULL, row_pointers,
+ number_of_rows);
+
+If you don't want libpng to handle the interlacing details, just call
+png_read_rows() PNG_INTERLACE_ADAM7_PASSES times to read in all the images.
+Each of the images is a valid image by itself; however, you will almost
+certainly need to distribute the pixels from each sub-image to the
+correct place. This is where everything gets very tricky.
+
+If you want to retrieve the separate images you must pass the correct
+number of rows to each successive call of png_read_rows(). The calculation
+gets pretty complicated for small images, where some sub-images may
+not even exist because either their width or height ends up zero.
+libpng provides two macros to help you in 1.5 and later versions:
+
+ png_uint_32 width = PNG_PASS_COLS(image_width, pass_number);
+ png_uint_32 height = PNG_PASS_ROWS(image_height, pass_number);
+
+Respectively these tell you the width and height of the sub-image
+corresponding to the numbered pass. 'pass' is in in the range 0 to 6 -
+this can be confusing because the specification refers to the same passes
+as 1 to 7! Be careful, you must check both the width and height before
+calling png_read_rows() and not call it for that pass if either is zero.
+
+You can, of course, read each sub-image row by row. If you want to
+produce optimal code to make a pixel-by-pixel transformation of an
+interlaced image this is the best approach; read each row of each pass,
+transform it, and write it out to a new interlaced image.
+
+If you want to de-interlace the image yourself libpng provides further
+macros to help that tell you where to place the pixels in the output image.
+Because the interlacing scheme is rectangular - sub-image pixels are always
+arranged on a rectangular grid - all you need to know for each pass is the
+starting column and row in the output image of the first pixel plus the
+spacing between each pixel. As of libpng 1.5 there are four macros to
+retrieve this information:
+
+ png_uint_32 x = PNG_PASS_START_COL(pass);
+ png_uint_32 y = PNG_PASS_START_ROW(pass);
+ png_uint_32 xStep = 1U << PNG_PASS_COL_SHIFT(pass);
+ png_uint_32 yStep = 1U << PNG_PASS_ROW_SHIFT(pass);
+
+These allow you to write the obvious loop:
+
+ png_uint_32 input_y = 0;
+ png_uint_32 output_y = PNG_PASS_START_ROW(pass);
+
+ while (output_y < output_image_height)
+ {
+ png_uint_32 input_x = 0;
+ png_uint_32 output_x = PNG_PASS_START_COL(pass);
+
+ while (output_x < output_image_width)
+ {
+ image[output_y][output_x] =
+ subimage[pass][input_y][input_x++];
+
+ output_x += xStep;
+ }
+
+ ++input_y;
+ output_y += yStep;
+ }
+
+Notice that the steps between successive output rows and columns are
+returned as shifts. This is possible because the pixels in the subimages
+are always a power of 2 apart - 1, 2, 4 or 8 pixels - in the original
+image. In practice you may need to directly calculate the output coordinate
+given an input coordinate. libpng provides two further macros for this
+purpose:
+
+ png_uint_32 output_x = PNG_COL_FROM_PASS_COL(input_x, pass);
+ png_uint_32 output_y = PNG_ROW_FROM_PASS_ROW(input_y, pass);
+
+Finally a pair of macros are provided to tell you if a particular image
+row or column appears in a given pass:
+
+ int col_in_pass = PNG_COL_IN_INTERLACE_PASS(output_x, pass);
+ int row_in_pass = PNG_ROW_IN_INTERLACE_PASS(output_y, pass);
+
+Bear in mind that you will probably also need to check the width and height
+of the pass in addition to the above to be sure the pass even exists!
+
+With any luck you are convinced by now that you don't want to do your own
+interlace handling. In reality normally the only good reason for doing this
+is if you are processing PNG files on a pixel-by-pixel basis and don't want
+to load the whole file into memory when it is interlaced.
+
+libpng includes a test program, pngvalid, that illustrates reading and
+writing of interlaced images. If you can't get interlacing to work in your
+code and don't want to leave it to libpng (the recommended approach), see
+how pngvalid.c does it.
+
+Finishing a sequential read
+
+After you are finished reading the image through the
+low-level interface, you can finish reading the file.
+
+If you want to use a different crc action for handling CRC errors in
+chunks after the image data, you can call png_set_crc_action()
+again at this point.
+
+If you are interested in comments or time, which may be stored either
+before or after the image data, you should pass the separate png_info
+struct if you want to keep the comments from before and after the image
+separate.
+
+ png_infop end_info = png_create_info_struct(png_ptr);
+
+ if (!end_info)
+ {
+ png_destroy_read_struct(&png_ptr, &info_ptr,
+ (png_infopp)NULL);
+ return (ERROR);
+ }
+
+ png_read_end(png_ptr, end_info);
+
+If you are not interested, you should still call png_read_end()
+but you can pass NULL, avoiding the need to create an end_info structure.
+If you do this, libpng will not process any chunks after IDAT other than
+skipping over them and perhaps (depending on whether you have called
+png_set_crc_action) checking their CRCs while looking for the IEND chunk.
+
+ png_read_end(png_ptr, (png_infop)NULL);
+
+If you don't call png_read_end(), then your file pointer will be
+left pointing to the first chunk after the last IDAT, which is probably
+not what you want if you expect to read something beyond the end of
+the PNG datastream.
+
+When you are done, you can free all memory allocated by libpng like this:
+
+ png_destroy_read_struct(&png_ptr, &info_ptr,
+ &end_info);
+
+or, if you didn't create an end_info structure,
+
+ png_destroy_read_struct(&png_ptr, &info_ptr,
+ (png_infopp)NULL);
+
+It is also possible to individually free the info_ptr members that
+point to libpng-allocated storage with the following function:
+
+ png_free_data(png_ptr, info_ptr, mask, seq)
+
+ mask - identifies data to be freed, a mask
+ containing the bitwise OR of one or
+ more of
+ PNG_FREE_PLTE, PNG_FREE_TRNS,
+ PNG_FREE_HIST, PNG_FREE_ICCP,
+ PNG_FREE_PCAL, PNG_FREE_ROWS,
+ PNG_FREE_SCAL, PNG_FREE_SPLT,
+ PNG_FREE_TEXT, PNG_FREE_UNKN,
+ or simply PNG_FREE_ALL
+
+ seq - sequence number of item to be freed
+ (-1 for all items)
+
+This function may be safely called when the relevant storage has
+already been freed, or has not yet been allocated, or was allocated
+by the user and not by libpng, and will in those cases do nothing.
+The "seq" parameter is ignored if only one item of the selected data
+type, such as PLTE, is allowed. If "seq" is not -1, and multiple items
+are allowed for the data type identified in the mask, such as text or
+sPLT, only the n'th item in the structure is freed, where n is "seq".
+
+The default behavior is only to free data that was allocated internally
+by libpng. This can be changed, so that libpng will not free the data,
+or so that it will free data that was allocated by the user with png_malloc()
+or png_calloc() and passed in via a png_set_*() function, with
+
+ png_data_freer(png_ptr, info_ptr, freer, mask)
+
+ freer - one of
+ PNG_DESTROY_WILL_FREE_DATA
+ PNG_SET_WILL_FREE_DATA
+ PNG_USER_WILL_FREE_DATA
+
+ mask - which data elements are affected
+ same choices as in png_free_data()
+
+This function only affects data that has already been allocated.
+You can call this function after reading the PNG data but before calling
+any png_set_*() functions, to control whether the user or the png_set_*()
+function is responsible for freeing any existing data that might be present,
+and again after the png_set_*() functions to control whether the user
+or png_destroy_*() is supposed to free the data. When the user assumes
+responsibility for libpng-allocated data, the application must use
+png_free() to free it, and when the user transfers responsibility to libpng
+for data that the user has allocated, the user must have used png_malloc()
+or png_calloc() to allocate it.
+
+If you allocated your row_pointers in a single block, as suggested above in
+the description of the high level read interface, you must not transfer
+responsibility for freeing it to the png_set_rows or png_read_destroy function,
+because they would also try to free the individual row_pointers[i].
+
+If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
+separately, do not transfer responsibility for freeing text_ptr to libpng,
+because when libpng fills a png_text structure it combines these members with
+the key member, and png_free_data() will free only text_ptr.key. Similarly,
+if you transfer responsibility for free'ing text_ptr from libpng to your
+application, your application must not separately free those members.
+
+The png_free_data() function will turn off the "valid" flag for anything
+it frees. If you need to turn the flag off for a chunk that was freed by
+your application instead of by libpng, you can use
+
+ png_set_invalid(png_ptr, info_ptr, mask);
+
+ mask - identifies the chunks to be made invalid,
+ containing the bitwise OR of one or
+ more of
+ PNG_INFO_gAMA, PNG_INFO_sBIT,
+ PNG_INFO_cHRM, PNG_INFO_PLTE,
+ PNG_INFO_tRNS, PNG_INFO_bKGD,
+ PNG_INFO_hIST, PNG_INFO_pHYs,
+ PNG_INFO_oFFs, PNG_INFO_tIME,
+ PNG_INFO_pCAL, PNG_INFO_sRGB,
+ PNG_INFO_iCCP, PNG_INFO_sPLT,
+ PNG_INFO_sCAL, PNG_INFO_IDAT
+
+For a more compact example of reading a PNG image, see the file example.c.
+
+Reading PNG files progressively
+
+The progressive reader is slightly different from the non-progressive
+reader. Instead of calling png_read_info(), png_read_rows(), and
+png_read_end(), you make one call to png_process_data(), which calls
+callbacks when it has the info, a row, or the end of the image. You
+set up these callbacks with png_set_progressive_read_fn(). You don't
+have to worry about the input/output functions of libpng, as you are
+giving the library the data directly in png_process_data(). I will
+assume that you have read the section on reading PNG files above,
+so I will only highlight the differences (although I will show
+all of the code).
+
+png_structp png_ptr;
+png_infop info_ptr;
+
+ /* An example code fragment of how you would
+ initialize the progressive reader in your
+ application. */
+ int
+ initialize_png_reader()
+ {
+ png_ptr = png_create_read_struct
+ (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+ user_error_fn, user_warning_fn);
+
+ if (!png_ptr)
+ return (ERROR);
+
+ info_ptr = png_create_info_struct(png_ptr);
+
+ if (!info_ptr)
+ {
+ png_destroy_read_struct(&png_ptr,
+ (png_infopp)NULL, (png_infopp)NULL);
+ return (ERROR);
+ }
+
+ if (setjmp(png_jmpbuf(png_ptr)))
+ {
+ png_destroy_read_struct(&png_ptr, &info_ptr,
+ (png_infopp)NULL);
+ return (ERROR);
+ }
+
+ /* This one's new. You can provide functions
+ to be called when the header info is valid,
+ when each row is completed, and when the image
+ is finished. If you aren't using all functions,
+ you can specify NULL parameters. Even when all
+ three functions are NULL, you need to call
+ png_set_progressive_read_fn(). You can use
+ any struct as the user_ptr (cast to a void pointer
+ for the function call), and retrieve the pointer
+ from inside the callbacks using the function
+
+ png_get_progressive_ptr(png_ptr);
+
+ which will return a void pointer, which you have
+ to cast appropriately.
+ */
+ png_set_progressive_read_fn(png_ptr, (void *)user_ptr,
+ info_callback, row_callback, end_callback);
+
+ return 0;
+ }
+
+ /* A code fragment that you call as you receive blocks
+ of data */
+ int
+ process_data(png_bytep buffer, png_uint_32 length)
+ {
+ if (setjmp(png_jmpbuf(png_ptr)))
+ {
+ png_destroy_read_struct(&png_ptr, &info_ptr,
+ (png_infopp)NULL);
+ return (ERROR);
+ }
+
+ /* This one's new also. Simply give it a chunk
+ of data from the file stream (in order, of
+ course). On machines with segmented memory
+ models machines, don't give it any more than
+ 64K. The library seems to run fine with sizes
+ of 4K. Although you can give it much less if
+ necessary (I assume you can give it chunks of
+ 1 byte, I haven't tried less than 256 bytes
+ yet). When this function returns, you may
+ want to display any rows that were generated
+ in the row callback if you don't already do
+ so there.
+ */
+ png_process_data(png_ptr, info_ptr, buffer, length);
+
+ /* At this point you can call png_process_data_skip if
+ you want to handle data the library will skip yourself;
+ it simply returns the number of bytes to skip (and stops
+ libpng skipping that number of bytes on the next
+ png_process_data call).
+ return 0;
+ }
+
+ /* This function is called (as set by
+ png_set_progressive_read_fn() above) when enough data
+ has been supplied so all of the header has been
+ read.
+ */
+ void
+ info_callback(png_structp png_ptr, png_infop info)
+ {
+ /* Do any setup here, including setting any of
+ the transformations mentioned in the Reading
+ PNG files section. For now, you _must_ call
+ either png_start_read_image() or
+ png_read_update_info() after all the
+ transformations are set (even if you don't set
+ any). You may start getting rows before
+ png_process_data() returns, so this is your
+ last chance to prepare for that.
+
+ This is where you turn on interlace handling,
+ assuming you don't want to do it yourself.
+
+ If you need to you can stop the processing of
+ your original input data at this point by calling
+ png_process_data_pause. This returns the number
+ of unprocessed bytes from the last png_process_data
+ call - it is up to you to ensure that the next call
+ sees these bytes again. If you don't want to bother
+ with this you can get libpng to cache the unread
+ bytes by setting the 'save' parameter (see png.h) but
+ then libpng will have to copy the data internally.
+ */
+ }
+
+ /* This function is called when each row of image
+ data is complete */
+ void
+ row_callback(png_structp png_ptr, png_bytep new_row,
+ png_uint_32 row_num, int pass)
+ {
+ /* If the image is interlaced, and you turned
+ on the interlace handler, this function will
+ be called for every row in every pass. Some
+ of these rows will not be changed from the
+ previous pass. When the row is not changed,
+ the new_row variable will be NULL. The rows
+ and passes are called in order, so you don't
+ really need the row_num and pass, but I'm
+ supplying them because it may make your life
+ easier.
+
+ If you did not turn on interlace handling then
+ the callback is called for each row of each
+ sub-image when the image is interlaced. In this
+ case 'row_num' is the row in the sub-image, not
+ the row in the output image as it is in all other
+ cases.
+
+ For the non-NULL rows of interlaced images when
+ you have switched on libpng interlace handling,
+ you must call png_progressive_combine_row()
+ passing in the row and the old row. You can
+ call this function for NULL rows (it will just
+ return) and for non-interlaced images (it just
+ does the memcpy for you) if it will make the
+ code easier. Thus, you can just do this for
+ all cases if you switch on interlace handling;
+ */
+
+ png_progressive_combine_row(png_ptr, old_row,
+ new_row);
+
+ /* where old_row is what was displayed
+ previously for the row. Note that the first
+ pass (pass == 0, really) will completely cover
+ the old row, so the rows do not have to be
+ initialized. After the first pass (and only
+ for interlaced images), you will have to pass
+ the current row, and the function will combine
+ the old row and the new row.
+
+ You can also call png_process_data_pause in this
+ callback - see above.
+ */
+ }
+
+ void
+ end_callback(png_structp png_ptr, png_infop info)
+ {
+ /* This function is called after the whole image
+ has been read, including any chunks after the
+ image (up to and including the IEND). You
+ will usually have the same info chunk as you
+ had in the header, although some data may have
+ been added to the comments and time fields.
+
+ Most people won't do much here, perhaps setting
+ a flag that marks the image as finished.
+ */
+ }
+
+
+
+IV. Writing
+
+Much of this is very similar to reading. However, everything of
+importance is repeated here, so you won't have to constantly look
+back up in the reading section to understand writing.
+
+Setup
+
+You will want to do the I/O initialization before you get into libpng,
+so if it doesn't work, you don't have anything to undo. If you are not
+using the standard I/O functions, you will need to replace them with
+custom writing functions. See the discussion under Customizing libpng.
+
+ FILE *fp = fopen(file_name, "wb");
+
+ if (!fp)
+ return (ERROR);
+
+Next, png_struct and png_info need to be allocated and initialized.
+As these can be both relatively large, you may not want to store these
+on the stack, unless you have stack space to spare. Of course, you
+will want to check if they return NULL. If you are also reading,
+you won't want to name your read structure and your write structure
+both "png_ptr"; you can call them anything you like, such as
+"read_ptr" and "write_ptr". Look at pngtest.c, for example.
+
+ png_structp png_ptr = png_create_write_struct
+ (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+ user_error_fn, user_warning_fn);
+
+ if (!png_ptr)
+ return (ERROR);
+
+ png_infop info_ptr = png_create_info_struct(png_ptr);
+ if (!info_ptr)
+ {
+ png_destroy_write_struct(&png_ptr,
+ (png_infopp)NULL);
+ return (ERROR);
+ }
+
+If you want to use your own memory allocation routines,
+define PNG_USER_MEM_SUPPORTED and use
+png_create_write_struct_2() instead of png_create_write_struct():
+
+ png_structp png_ptr = png_create_write_struct_2
+ (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+ user_error_fn, user_warning_fn, (png_voidp)
+ user_mem_ptr, user_malloc_fn, user_free_fn);
+
+After you have these structures, you will need to set up the
+error handling. When libpng encounters an error, it expects to
+longjmp() back to your routine. Therefore, you will need to call
+setjmp() and pass the png_jmpbuf(png_ptr). If you
+write the file from different routines, you will need to update
+the png_jmpbuf(png_ptr) every time you enter a new routine that will
+call a png_*() function. See your documentation of setjmp/longjmp
+for your compiler for more information on setjmp/longjmp. See
+the discussion on libpng error handling in the Customizing Libpng
+section below for more information on the libpng error handling.
+
+ if (setjmp(png_jmpbuf(png_ptr)))
+ {
+ png_destroy_write_struct(&png_ptr, &info_ptr);
+ fclose(fp);
+ return (ERROR);
+ }
+ ...
+ return;
+
+If you would rather avoid the complexity of setjmp/longjmp issues,
+you can compile libpng with PNG_NO_SETJMP, in which case
+errors will result in a call to PNG_ABORT() which defaults to abort().
+
+You can #define PNG_ABORT() to a function that does something
+more useful than abort(), as long as your function does not
+return.
+
+Checking for invalid palette index on write was added at libpng
+1.5.10. If a pixel contains an invalid (out-of-range) index libpng issues
+a benign error. This is enabled by default because this condition is an
+error according to the PNG specification, Clause 11.3.2, but the error can
+be ignored in each png_ptr with
+
+ png_set_check_for_invalid_index(png_ptr, 0);
+
+If the error is ignored, or if png_benign_error() treats it as a warning,
+any invalid pixels are written as-is by the encoder, resulting in an
+invalid PNG datastream as output. In this case the application is
+responsible for ensuring that the pixel indexes are in range when it writes
+a PLTE chunk with fewer entries than the bit depth would allow.
+
+Now you need to set up the output code. The default for libpng is to
+use the C function fwrite(). If you use this, you will need to pass a
+valid FILE * in the function png_init_io(). Be sure that the file is
+opened in binary mode. Again, if you wish to handle writing data in
+another way, see the discussion on libpng I/O handling in the Customizing
+Libpng section below.
+
+ png_init_io(png_ptr, fp);
+
+If you are embedding your PNG into a datastream such as MNG, and don't
+want libpng to write the 8-byte signature, or if you have already
+written the signature in your application, use
+
+ png_set_sig_bytes(png_ptr, 8);
+
+to inform libpng that it should not write a signature.
+
+Write callbacks
+
+At this point, you can set up a callback function that will be
+called after each row has been written, which you can use to control
+a progress meter or the like. It's demonstrated in pngtest.c.
+You must supply a function
+
+ void write_row_callback(png_structp png_ptr, png_uint_32 row,
+ int pass);
+ {
+ /* put your code here */
+ }
+
+(You can give it another name that you like instead of "write_row_callback")
+
+To inform libpng about your function, use
+
+ png_set_write_status_fn(png_ptr, write_row_callback);
+
+When this function is called the row has already been completely processed and
+it has also been written out. The 'row' and 'pass' refer to the next row to be
+handled. For the
+non-interlaced case the row that was just handled is simply one less than the
+passed in row number, and pass will always be 0. For the interlaced case the
+same applies unless the row value is 0, in which case the row just handled was
+the last one from one of the preceding passes. Because interlacing may skip a
+pass you cannot be sure that the preceding pass is just 'pass-1', if you really
+need to know what the last pass is record (row,pass) from the callback and use
+the last recorded value each time.
+
+As with the user transform you can find the output row using the
+PNG_ROW_FROM_PASS_ROW macro.
+
+You now have the option of modifying how the compression library will
+run. The following functions are mainly for testing, but may be useful
+in some cases, like if you need to write PNG files extremely fast and
+are willing to give up some compression, or if you want to get the
+maximum possible compression at the expense of slower writing. If you
+have no special needs in this area, let the library do what it wants by
+not calling this function at all, as it has been tuned to deliver a good
+speed/compression ratio. The second parameter to png_set_filter() is
+the filter method, for which the only valid values are 0 (as of the
+July 1999 PNG specification, version 1.2) or 64 (if you are writing
+a PNG datastream that is to be embedded in a MNG datastream). The third
+parameter is a flag that indicates which filter type(s) are to be tested
+for each scanline. See the PNG specification for details on the specific
+filter types.
+
+
+ /* turn on or off filtering, and/or choose
+ specific filters. You can use either a single
+ PNG_FILTER_VALUE_NAME or the bitwise OR of one
+ or more PNG_FILTER_NAME masks.
+ */
+ png_set_filter(png_ptr, 0,
+ PNG_FILTER_NONE | PNG_FILTER_VALUE_NONE |
+ PNG_FILTER_SUB | PNG_FILTER_VALUE_SUB |
+ PNG_FILTER_UP | PNG_FILTER_VALUE_UP |
+ PNG_FILTER_AVG | PNG_FILTER_VALUE_AVG |
+ PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH|
+ PNG_ALL_FILTERS);
+
+If an application wants to start and stop using particular filters during
+compression, it should start out with all of the filters (to ensure that
+the previous row of pixels will be stored in case it's needed later),
+and then add and remove them after the start of compression.
+
+If you are writing a PNG datastream that is to be embedded in a MNG
+datastream, the second parameter can be either 0 or 64.
+
+The png_set_compression_*() functions interface to the zlib compression
+library, and should mostly be ignored unless you really know what you are
+doing. The only generally useful call is png_set_compression_level()
+which changes how much time zlib spends on trying to compress the image
+data. See the Compression Library (zlib.h and algorithm.txt, distributed
+with zlib) for details on the compression levels.
+
+ #include zlib.h
+
+ /* Set the zlib compression level */
+ png_set_compression_level(png_ptr,
+ Z_BEST_COMPRESSION);
+
+ /* Set other zlib parameters for compressing IDAT */
+ png_set_compression_mem_level(png_ptr, 8);
+ png_set_compression_strategy(png_ptr,
+ Z_DEFAULT_STRATEGY);
+ png_set_compression_window_bits(png_ptr, 15);
+ png_set_compression_method(png_ptr, 8);
+ png_set_compression_buffer_size(png_ptr, 8192)
+
+ /* Set zlib parameters for text compression
+ * If you don't call these, the parameters
+ * fall back on those defined for IDAT chunks
+ */
+ png_set_text_compression_mem_level(png_ptr, 8);
+ png_set_text_compression_strategy(png_ptr,
+ Z_DEFAULT_STRATEGY);
+ png_set_text_compression_window_bits(png_ptr, 15);
+ png_set_text_compression_method(png_ptr, 8);
+
+Setting the contents of info for output
+
+You now need to fill in the png_info structure with all the data you
+wish to write before the actual image. Note that the only thing you
+are allowed to write after the image is the text chunks and the time
+chunk (as of PNG Specification 1.2, anyway). See png_write_end() and
+the latest PNG specification for more information on that. If you
+wish to write them before the image, fill them in now, and flag that
+data as being valid. If you want to wait until after the data, don't
+fill them until png_write_end(). For all the fields in png_info and
+their data types, see png.h. For explanations of what the fields
+contain, see the PNG specification.
+
+Some of the more important parts of the png_info are:
+
+ png_set_IHDR(png_ptr, info_ptr, width, height,
+ bit_depth, color_type, interlace_type,
+ compression_type, filter_method)
+
+ width - holds the width of the image
+ in pixels (up to 2^31).
+
+ height - holds the height of the image
+ in pixels (up to 2^31).
+
+ bit_depth - holds the bit depth of one of the
+ image channels.
+ (valid values are 1, 2, 4, 8, 16
+ and depend also on the
+ color_type. See also significant
+ bits (sBIT) below).
+
+ color_type - describes which color/alpha
+ channels are present.
+ PNG_COLOR_TYPE_GRAY
+ (bit depths 1, 2, 4, 8, 16)
+ PNG_COLOR_TYPE_GRAY_ALPHA
+ (bit depths 8, 16)
+ PNG_COLOR_TYPE_PALETTE
+ (bit depths 1, 2, 4, 8)
+ PNG_COLOR_TYPE_RGB
+ (bit_depths 8, 16)
+ PNG_COLOR_TYPE_RGB_ALPHA
+ (bit_depths 8, 16)
+
+ PNG_COLOR_MASK_PALETTE
+ PNG_COLOR_MASK_COLOR
+ PNG_COLOR_MASK_ALPHA
+
+ interlace_type - PNG_INTERLACE_NONE or
+ PNG_INTERLACE_ADAM7
+
+ compression_type - (must be
+ PNG_COMPRESSION_TYPE_DEFAULT)
+
+ filter_method - (must be PNG_FILTER_TYPE_DEFAULT
+ or, if you are writing a PNG to
+ be embedded in a MNG datastream,
+ can also be
+ PNG_INTRAPIXEL_DIFFERENCING)
+
+If you call png_set_IHDR(), the call must appear before any of the
+other png_set_*() functions, because they might require access to some of
+the IHDR settings. The remaining png_set_*() functions can be called
+in any order.
+
+If you wish, you can reset the compression_type, interlace_type, or
+filter_method later by calling png_set_IHDR() again; if you do this, the
+width, height, bit_depth, and color_type must be the same in each call.
+
+ png_set_PLTE(png_ptr, info_ptr, palette,
+ num_palette);
+
+ palette - the palette for the file
+ (array of png_color)
+ num_palette - number of entries in the palette
+
+
+ png_set_gAMA(png_ptr, info_ptr, file_gamma);
+ png_set_gAMA_fixed(png_ptr, info_ptr, int_file_gamma);
+
+ file_gamma - the gamma at which the image was
+ created (PNG_INFO_gAMA)
+
+ int_file_gamma - 100,000 times the gamma at which
+ the image was created
+
+ png_set_cHRM(png_ptr, info_ptr, white_x, white_y, red_x, red_y,
+ green_x, green_y, blue_x, blue_y)
+ png_set_cHRM_XYZ(png_ptr, info_ptr, red_X, red_Y, red_Z, green_X,
+ green_Y, green_Z, blue_X, blue_Y, blue_Z)
+ png_set_cHRM_fixed(png_ptr, info_ptr, int_white_x, int_white_y,
+ int_red_x, int_red_y, int_green_x, int_green_y,
+ int_blue_x, int_blue_y)
+ png_set_cHRM_XYZ_fixed(png_ptr, info_ptr, int_red_X, int_red_Y,
+ int_red_Z, int_green_X, int_green_Y, int_green_Z,
+ int_blue_X, int_blue_Y, int_blue_Z)
+
+ {white,red,green,blue}_{x,y}
+ A color space encoding specified using the chromaticities
+ of the end points and the white point.
+
+ {red,green,blue}_{X,Y,Z}
+ A color space encoding specified using the encoding end
+ points - the CIE tristimulus specification of the intended
+ color of the red, green and blue channels in the PNG RGB
+ data. The white point is simply the sum of the three end
+ points.
+
+ png_set_sRGB(png_ptr, info_ptr, srgb_intent);
+
+ srgb_intent - the rendering intent
+ (PNG_INFO_sRGB) The presence of
+ the sRGB chunk means that the pixel
+ data is in the sRGB color space.
+ This chunk also implies specific
+ values of gAMA and cHRM. Rendering
+ intent is the CSS-1 property that
+ has been defined by the International
+ Color Consortium
+ (http://www.color.org).
+ It can be one of
+ PNG_sRGB_INTENT_SATURATION,
+ PNG_sRGB_INTENT_PERCEPTUAL,
+ PNG_sRGB_INTENT_ABSOLUTE, or
+ PNG_sRGB_INTENT_RELATIVE.
+
+
+ png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr,
+ srgb_intent);
+
+ srgb_intent - the rendering intent
+ (PNG_INFO_sRGB) The presence of the
+ sRGB chunk means that the pixel
+ data is in the sRGB color space.
+ This function also causes gAMA and
+ cHRM chunks with the specific values
+ that are consistent with sRGB to be
+ written.
+
+ png_set_iCCP(png_ptr, info_ptr, name, compression_type,
+ profile, proflen);
+
+ name - The profile name.
+
+ compression_type - The compression type; always
+ PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
+ You may give NULL to this argument to
+ ignore it.
+
+ profile - International Color Consortium color
+ profile data. May contain NULs.
+
+ proflen - length of profile data in bytes.
+
+ png_set_sBIT(png_ptr, info_ptr, sig_bit);
+
+ sig_bit - the number of significant bits for
+ (PNG_INFO_sBIT) each of the gray, red,
+ green, and blue channels, whichever are
+ appropriate for the given color type
+ (png_color_16)
+
+ png_set_tRNS(png_ptr, info_ptr, trans_alpha,
+ num_trans, trans_color);
+
+ trans_alpha - array of alpha (transparency)
+ entries for palette (PNG_INFO_tRNS)
+
+ num_trans - number of transparent entries
+ (PNG_INFO_tRNS)
+
+ trans_color - graylevel or color sample values
+ (in order red, green, blue) of the
+ single transparent color for
+ non-paletted images (PNG_INFO_tRNS)
+
+ png_set_hIST(png_ptr, info_ptr, hist);
+
+ hist - histogram of palette (array of
+ png_uint_16) (PNG_INFO_hIST)
+
+ png_set_tIME(png_ptr, info_ptr, mod_time);
+
+ mod_time - time image was last modified
+ (PNG_VALID_tIME)
+
+ png_set_bKGD(png_ptr, info_ptr, background);
+
+ background - background color (of type
+ png_color_16p) (PNG_VALID_bKGD)
+
+ png_set_text(png_ptr, info_ptr, text_ptr, num_text);
+
+ text_ptr - array of png_text holding image
+ comments
+
+ text_ptr[i].compression - type of compression used
+ on "text" PNG_TEXT_COMPRESSION_NONE
+ PNG_TEXT_COMPRESSION_zTXt
+ PNG_ITXT_COMPRESSION_NONE
+ PNG_ITXT_COMPRESSION_zTXt
+ text_ptr[i].key - keyword for comment. Must contain
+ 1-79 characters.
+ text_ptr[i].text - text comments for current
+ keyword. Can be NULL or empty.
+ text_ptr[i].text_length - length of text string,
+ after decompression, 0 for iTXt
+ text_ptr[i].itxt_length - length of itxt string,
+ after decompression, 0 for tEXt/zTXt
+ text_ptr[i].lang - language of comment (NULL or
+ empty for unknown).
+ text_ptr[i].translated_keyword - keyword in UTF-8 (NULL
+ or empty for unknown).
+
+ Note that the itxt_length, lang, and lang_key
+ members of the text_ptr structure only exist when the
+ library is built with iTXt chunk support. Prior to
+ libpng-1.4.0 the library was built by default without
+ iTXt support. Also note that when iTXt is supported,
+ they contain NULL pointers when the "compression"
+ field contains PNG_TEXT_COMPRESSION_NONE or
+ PNG_TEXT_COMPRESSION_zTXt.
+
+ num_text - number of comments
+
+ png_set_sPLT(png_ptr, info_ptr, &palette_ptr,
+ num_spalettes);
+
+ palette_ptr - array of png_sPLT_struct structures
+ to be added to the list of palettes
+ in the info structure.
+ num_spalettes - number of palette structures to be
+ added.
+
+ png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y,
+ unit_type);
+
+ offset_x - positive offset from the left
+ edge of the screen
+
+ offset_y - positive offset from the top
+ edge of the screen
+
+ unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
+
+ png_set_pHYs(png_ptr, info_ptr, res_x, res_y,
+ unit_type);
+
+ res_x - pixels/unit physical resolution
+ in x direction
+
+ res_y - pixels/unit physical resolution
+ in y direction
+
+ unit_type - PNG_RESOLUTION_UNKNOWN,
+ PNG_RESOLUTION_METER
+
+ png_set_sCAL(png_ptr, info_ptr, unit, width, height)
+
+ unit - physical scale units (an integer)
+
+ width - width of a pixel in physical scale units
+
+ height - height of a pixel in physical scale units
+ (width and height are doubles)
+
+ png_set_sCAL_s(png_ptr, info_ptr, unit, width, height)
+
+ unit - physical scale units (an integer)
+
+ width - width of a pixel in physical scale units
+ expressed as a string
+
+ height - height of a pixel in physical scale units
+ (width and height are strings like "2.54")
+
+ png_set_unknown_chunks(png_ptr, info_ptr, &unknowns,
+ num_unknowns)
+
+ unknowns - array of png_unknown_chunk
+ structures holding unknown chunks
+ unknowns[i].name - name of unknown chunk
+ unknowns[i].data - data of unknown chunk
+ unknowns[i].size - size of unknown chunk's data
+ unknowns[i].location - position to write chunk in file
+ 0: do not write chunk
+ PNG_HAVE_IHDR: before PLTE
+ PNG_HAVE_PLTE: before IDAT
+ PNG_AFTER_IDAT: after IDAT
+
+The "location" member is set automatically according to
+what part of the output file has already been written.
+You can change its value after calling png_set_unknown_chunks()
+as demonstrated in pngtest.c. Within each of the "locations",
+the chunks are sequenced according to their position in the
+structure (that is, the value of "i", which is the order in which
+the chunk was either read from the input file or defined with
+png_set_unknown_chunks).
+
+A quick word about text and num_text. text is an array of png_text
+structures. num_text is the number of valid structures in the array.
+Each png_text structure holds a language code, a keyword, a text value,
+and a compression type.
+
+The compression types have the same valid numbers as the compression
+types of the image data. Currently, the only valid number is zero.
+However, you can store text either compressed or uncompressed, unlike
+images, which always have to be compressed. So if you don't want the
+text compressed, set the compression type to PNG_TEXT_COMPRESSION_NONE.
+Because tEXt and zTXt chunks don't have a language field, if you
+specify PNG_TEXT_COMPRESSION_NONE or PNG_TEXT_COMPRESSION_zTXt
+any language code or translated keyword will not be written out.
+
+Until text gets around a few hundred bytes, it is not worth compressing it.
+After the text has been written out to the file, the compression type
+is set to PNG_TEXT_COMPRESSION_NONE_WR or PNG_TEXT_COMPRESSION_zTXt_WR,
+so that it isn't written out again at the end (in case you are calling
+png_write_end() with the same struct).
+
+The keywords that are given in the PNG Specification are:
+
+ Title Short (one line) title or
+ caption for image
+
+ Author Name of image's creator
+
+ Description Description of image (possibly long)
+
+ Copyright Copyright notice
+
+ Creation Time Time of original image creation
+ (usually RFC 1123 format, see below)
+
+ Software Software used to create the image
+
+ Disclaimer Legal disclaimer
+
+ Warning Warning of nature of content
+
+ Source Device used to create the image
+
+ Comment Miscellaneous comment; conversion
+ from other image format
+
+The keyword-text pairs work like this. Keywords should be short
+simple descriptions of what the comment is about. Some typical
+keywords are found in the PNG specification, as is some recommendations
+on keywords. You can repeat keywords in a file. You can even write
+some text before the image and some after. For example, you may want
+to put a description of the image before the image, but leave the
+disclaimer until after, so viewers working over modem connections
+don't have to wait for the disclaimer to go over the modem before
+they start seeing the image. Finally, keywords should be full
+words, not abbreviations. Keywords and text are in the ISO 8859-1
+(Latin-1) character set (a superset of regular ASCII) and can not
+contain NUL characters, and should not contain control or other
+unprintable characters. To make the comments widely readable, stick
+with basic ASCII, and avoid machine specific character set extensions
+like the IBM-PC character set. The keyword must be present, but
+you can leave off the text string on non-compressed pairs.
+Compressed pairs must have a text string, as only the text string
+is compressed anyway, so the compression would be meaningless.
+
+PNG supports modification time via the png_time structure. Two
+conversion routines are provided, png_convert_from_time_t() for
+time_t and png_convert_from_struct_tm() for struct tm. The
+time_t routine uses gmtime(). You don't have to use either of
+these, but if you wish to fill in the png_time structure directly,
+you should provide the time in universal time (GMT) if possible
+instead of your local time. Note that the year number is the full
+year (e.g. 1998, rather than 98 - PNG is year 2000 compliant!), and
+that months start with 1.
+
+If you want to store the time of the original image creation, you should
+use a plain tEXt chunk with the "Creation Time" keyword. This is
+necessary because the "creation time" of a PNG image is somewhat vague,
+depending on whether you mean the PNG file, the time the image was
+created in a non-PNG format, a still photo from which the image was
+scanned, or possibly the subject matter itself. In order to facilitate
+machine-readable dates, it is recommended that the "Creation Time"
+tEXt chunk use RFC 1123 format dates (e.g. "22 May 1997 18:07:10 GMT"),
+although this isn't a requirement. Unlike the tIME chunk, the
+"Creation Time" tEXt chunk is not expected to be automatically changed
+by the software. To facilitate the use of RFC 1123 dates, a function
+png_convert_to_rfc1123_buffer(buffer, png_timep) is provided to
+convert from PNG time to an RFC 1123 format string. The caller must provide
+a writeable buffer of at least 29 bytes.
+
+Writing unknown chunks
+
+You can use the png_set_unknown_chunks function to queue up private chunks
+for writing. You give it a chunk name, location, raw data, and a size. You
+also must use png_set_keep_unknown_chunks() to ensure that libpng will
+handle them. That's all there is to it. The chunks will be written by the
+next following png_write_info_before_PLTE, png_write_info, or png_write_end
+function, depending upon the specified location. Any chunks previously
+read into the info structure's unknown-chunk list will also be written out
+in a sequence that satisfies the PNG specification's ordering rules.
+
+Here is an example of writing two private chunks, prVt and miNE:
+
+ #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
+ /* Set unknown chunk data */
+ png_unknown_chunk unk_chunk[2];
+ strcpy((char *) unk_chunk[0].name, "prVt";
+ unk_chunk[0].data = (unsigned char *) "PRIVATE DATA";
+ unk_chunk[0].size = strlen(unk_chunk[0].data)+1;
+ unk_chunk[0].location = PNG_HAVE_IHDR;
+ strcpy((char *) unk_chunk[1].name, "miNE";
+ unk_chunk[1].data = (unsigned char *) "MY CHUNK DATA";
+ unk_chunk[1].size = strlen(unk_chunk[0].data)+1;
+ unk_chunk[1].location = PNG_AFTER_IDAT;
+ png_set_unknown_chunks(write_ptr, write_info_ptr,
+ unk_chunk, 2);
+ /* Needed because miNE is not safe-to-copy */
+ png_set_keep_unknown_chunks(png, PNG_HANDLE_CHUNK_ALWAYS,
+ (png_bytep) "miNE", 1);
+ # if PNG_LIBPNG_VER < 10600
+ /* Deal with unknown chunk location bug in 1.5.x and earlier */
+ png_set_unknown_chunk_location(png, info, 0, PNG_HAVE_IHDR);
+ png_set_unknown_chunk_location(png, info, 1, PNG_AFTER_IDAT);
+ # endif
+ # if PNG_LIBPNG_VER < 10500
+ /* PNG_AFTER_IDAT writes two copies of the chunk prior to libpng-1.5.0,
+ * one before IDAT and another after IDAT, so don't use it; only use
+ * PNG_HAVE_IHDR location. This call resets the location previously
+ * set by assignment and png_set_unknown_chunk_location() for chunk 1.
+ */
+ png_set_unknown_chunk_location(png, info, 1, PNG_HAVE_IHDR);
+ # endif
+ #endif
+
+The high-level write interface
+
+At this point there are two ways to proceed; through the high-level
+write interface, or through a sequence of low-level write operations.
+You can use the high-level interface if your image data is present
+in the info structure. All defined output
+transformations are permitted, enabled by the following masks.
+
+ PNG_TRANSFORM_IDENTITY No transformation
+ PNG_TRANSFORM_PACKING Pack 1, 2 and 4-bit samples
+ PNG_TRANSFORM_PACKSWAP Change order of packed
+ pixels to LSB first
+ PNG_TRANSFORM_INVERT_MONO Invert monochrome images
+ PNG_TRANSFORM_SHIFT Normalize pixels to the
+ sBIT depth
+ PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA
+ to BGRA
+ PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
+ to AG
+ PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
+ to transparency
+ PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
+ PNG_TRANSFORM_STRIP_FILLER Strip out filler
+ bytes (deprecated).
+ PNG_TRANSFORM_STRIP_FILLER_BEFORE Strip out leading
+ filler bytes
+ PNG_TRANSFORM_STRIP_FILLER_AFTER Strip out trailing
+ filler bytes
+
+If you have valid image data in the info structure (you can use
+png_set_rows() to put image data in the info structure), simply do this:
+
+ png_write_png(png_ptr, info_ptr, png_transforms, NULL)
+
+where png_transforms is an integer containing the bitwise OR of some set of
+transformation flags. This call is equivalent to png_write_info(),
+followed the set of transformations indicated by the transform mask,
+then png_write_image(), and finally png_write_end().
+
+(The final parameter of this call is not yet used. Someday it might point
+to transformation parameters required by some future output transform.)
+
+You must use png_transforms and not call any png_set_transform() functions
+when you use png_write_png().
+
+The low-level write interface
+
+If you are going the low-level route instead, you are now ready to
+write all the file information up to the actual image data. You do
+this with a call to png_write_info().
+
+ png_write_info(png_ptr, info_ptr);
+
+Note that there is one transformation you may need to do before
+png_write_info(). In PNG files, the alpha channel in an image is the
+level of opacity. If your data is supplied as a level of transparency,
+you can invert the alpha channel before you write it, so that 0 is
+fully transparent and 255 (in 8-bit or paletted images) or 65535
+(in 16-bit images) is fully opaque, with
+
+ png_set_invert_alpha(png_ptr);
+
+This must appear before png_write_info() instead of later with the
+other transformations because in the case of paletted images the tRNS
+chunk data has to be inverted before the tRNS chunk is written. If
+your image is not a paletted image, the tRNS data (which in such cases
+represents a single color to be rendered as transparent) won't need to
+be changed, and you can safely do this transformation after your
+png_write_info() call.
+
+If you need to write a private chunk that you want to appear before
+the PLTE chunk when PLTE is present, you can write the PNG info in
+two steps, and insert code to write your own chunk between them:
+
+ png_write_info_before_PLTE(png_ptr, info_ptr);
+ png_set_unknown_chunks(png_ptr, info_ptr, ...);
+ png_write_info(png_ptr, info_ptr);
+
+After you've written the file information, you can set up the library
+to handle any special transformations of the image data. The various
+ways to transform the data will be described in the order that they
+should occur. This is important, as some of these change the color
+type and/or bit depth of the data, and some others only work on
+certain color types and bit depths. Even though each transformation
+checks to see if it has data that it can do something with, you should
+make sure to only enable a transformation if it will be valid for the
+data. For example, don't swap red and blue on grayscale data.
+
+PNG files store RGB pixels packed into 3 or 6 bytes. This code tells
+the library to strip input data that has 4 or 8 bytes per pixel down
+to 3 or 6 bytes (or strip 2 or 4-byte grayscale+filler data to 1 or 2
+bytes per pixel).
+
+ png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
+
+where the 0 is unused, and the location is either PNG_FILLER_BEFORE or
+PNG_FILLER_AFTER, depending upon whether the filler byte in the pixel
+is stored XRGB or RGBX.
+
+PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
+they can, resulting in, for example, 8 pixels per byte for 1 bit files.
+If the data is supplied at 1 pixel per byte, use this code, which will
+correctly pack the pixels into a single byte:
+
+ png_set_packing(png_ptr);
+
+PNG files reduce possible bit depths to 1, 2, 4, 8, and 16. If your
+data is of another bit depth, you can write an sBIT chunk into the
+file so that decoders can recover the original data if desired.
+
+ /* Set the true bit depth of the image data */
+ if (color_type & PNG_COLOR_MASK_COLOR)
+ {
+ sig_bit.red = true_bit_depth;
+ sig_bit.green = true_bit_depth;
+ sig_bit.blue = true_bit_depth;
+ }
+
+ else
+ {
+ sig_bit.gray = true_bit_depth;
+ }
+
+ if (color_type & PNG_COLOR_MASK_ALPHA)
+ {
+ sig_bit.alpha = true_bit_depth;
+ }
+
+ png_set_sBIT(png_ptr, info_ptr, &sig_bit);
+
+If the data is stored in the row buffer in a bit depth other than
+one supported by PNG (e.g. 3 bit data in the range 0-7 for a 4-bit PNG),
+this will scale the values to appear to be the correct bit depth as
+is required by PNG.
+
+ png_set_shift(png_ptr, &sig_bit);
+
+PNG files store 16-bit pixels in network byte order (big-endian,
+ie. most significant bits first). This code would be used if they are
+supplied the other way (little-endian, i.e. least significant bits
+first, the way PCs store them):
+
+ if (bit_depth > 8)
+ png_set_swap(png_ptr);
+
+If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
+need to change the order the pixels are packed into bytes, you can use:
+
+ if (bit_depth < 8)
+ png_set_packswap(png_ptr);
+
+PNG files store 3 color pixels in red, green, blue order. This code
+would be used if they are supplied as blue, green, red:
+
+ png_set_bgr(png_ptr);
+
+PNG files describe monochrome as black being zero and white being
+one. This code would be used if the pixels are supplied with this reversed
+(black being one and white being zero):
+
+ png_set_invert_mono(png_ptr);
+
+Finally, you can write your own transformation function if none of
+the existing ones meets your needs. This is done by setting a callback
+with
+
+ png_set_write_user_transform_fn(png_ptr,
+ write_transform_fn);
+
+You must supply the function
+
+ void write_transform_fn(png_structp png_ptr, png_row_infop
+ row_info, png_bytep data)
+
+See pngtest.c for a working example. Your function will be called
+before any of the other transformations are processed. If supported
+libpng also supplies an information routine that may be called from
+your callback:
+
+ png_get_current_row_number(png_ptr);
+ png_get_current_pass_number(png_ptr);
+
+This returns the current row passed to the transform. With interlaced
+images the value returned is the row in the input sub-image image. Use
+PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
+find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass).
+
+The discussion of interlace handling above contains more information on how to
+use these values.
+
+You can also set up a pointer to a user structure for use by your
+callback function.
+
+ png_set_user_transform_info(png_ptr, user_ptr, 0, 0);
+
+The user_channels and user_depth parameters of this function are ignored
+when writing; you can set them to zero as shown.
+
+You can retrieve the pointer via the function png_get_user_transform_ptr().
+For example:
+
+ voidp write_user_transform_ptr =
+ png_get_user_transform_ptr(png_ptr);
+
+It is possible to have libpng flush any pending output, either manually,
+or automatically after a certain number of lines have been written. To
+flush the output stream a single time call:
+
+ png_write_flush(png_ptr);
+
+and to have libpng flush the output stream periodically after a certain
+number of scanlines have been written, call:
+
+ png_set_flush(png_ptr, nrows);
+
+Note that the distance between rows is from the last time png_write_flush()
+was called, or the first row of the image if it has never been called.
+So if you write 50 lines, and then png_set_flush 25, it will flush the
+output on the next scanline, and every 25 lines thereafter, unless
+png_write_flush() is called before 25 more lines have been written.
+If nrows is too small (less than about 10 lines for a 640 pixel wide
+RGB image) the image compression may decrease noticeably (although this
+may be acceptable for real-time applications). Infrequent flushing will
+only degrade the compression performance by a few percent over images
+that do not use flushing.
+
+Writing the image data
+
+That's it for the transformations. Now you can write the image data.
+The simplest way to do this is in one function call. If you have the
+whole image in memory, you can just call png_write_image() and libpng
+will write the image. You will need to pass in an array of pointers to
+each row. This function automatically handles interlacing, so you don't
+need to call png_set_interlace_handling() or call this function multiple
+times, or any of that other stuff necessary with png_write_rows().
+
+ png_write_image(png_ptr, row_pointers);
+
+where row_pointers is:
+
+ png_byte *row_pointers[height];
+
+You can point to void or char or whatever you use for pixels.
+
+If you don't want to write the whole image at once, you can
+use png_write_rows() instead. If the file is not interlaced,
+this is simple:
+
+ png_write_rows(png_ptr, row_pointers,
+ number_of_rows);
+
+row_pointers is the same as in the png_write_image() call.
+
+If you are just writing one row at a time, you can do this with
+a single row_pointer instead of an array of row_pointers:
+
+ png_bytep row_pointer = row;
+
+ png_write_row(png_ptr, row_pointer);
+
+When the file is interlaced, things can get a good deal more complicated.
+The only currently (as of the PNG Specification version 1.2, dated July
+1999) defined interlacing scheme for PNG files is the "Adam7" interlace
+scheme, that breaks down an image into seven smaller images of varying
+size. libpng will build these images for you, or you can do them
+yourself. If you want to build them yourself, see the PNG specification
+for details of which pixels to write when.
+
+If you don't want libpng to handle the interlacing details, just
+use png_set_interlace_handling() and call png_write_rows() the
+correct number of times to write all the sub-images
+(png_set_interlace_handling() returns the number of sub-images.)
+
+If you want libpng to build the sub-images, call this before you start
+writing any rows:
+
+ number_of_passes = png_set_interlace_handling(png_ptr);
+
+This will return the number of passes needed. Currently, this is seven,
+but may change if another interlace type is added.
+
+Then write the complete image number_of_passes times.
+
+ png_write_rows(png_ptr, row_pointers, number_of_rows);
+
+Think carefully before you write an interlaced image. Typically code that
+reads such images reads all the image data into memory, uncompressed, before
+doing any processing. Only code that can display an image on the fly can
+take advantage of the interlacing and even then the image has to be exactly
+the correct size for the output device, because scaling an image requires
+adjacent pixels and these are not available until all the passes have been
+read.
+
+If you do write an interlaced image you will hardly ever need to handle
+the interlacing yourself. Call png_set_interlace_handling() and use the
+approach described above.
+
+The only time it is conceivable that you will really need to write an
+interlaced image pass-by-pass is when you have read one pass by pass and
+made some pixel-by-pixel transformation to it, as described in the read
+code above. In this case use the PNG_PASS_ROWS and PNG_PASS_COLS macros
+to determine the size of each sub-image in turn and simply write the rows
+you obtained from the read code.
+
+Finishing a sequential write
+
+After you are finished writing the image, you should finish writing
+the file. If you are interested in writing comments or time, you should
+pass an appropriately filled png_info pointer. If you are not interested,
+you can pass NULL.
+
+ png_write_end(png_ptr, info_ptr);
+
+When you are done, you can free all memory used by libpng like this:
+
+ png_destroy_write_struct(&png_ptr, &info_ptr);
+
+It is also possible to individually free the info_ptr members that
+point to libpng-allocated storage with the following function:
+
+ png_free_data(png_ptr, info_ptr, mask, seq)
+
+ mask - identifies data to be freed, a mask
+ containing the bitwise OR of one or
+ more of
+ PNG_FREE_PLTE, PNG_FREE_TRNS,
+ PNG_FREE_HIST, PNG_FREE_ICCP,
+ PNG_FREE_PCAL, PNG_FREE_ROWS,
+ PNG_FREE_SCAL, PNG_FREE_SPLT,
+ PNG_FREE_TEXT, PNG_FREE_UNKN,
+ or simply PNG_FREE_ALL
+
+ seq - sequence number of item to be freed
+ (-1 for all items)
+
+This function may be safely called when the relevant storage has
+already been freed, or has not yet been allocated, or was allocated
+by the user and not by libpng, and will in those cases do nothing.
+The "seq" parameter is ignored if only one item of the selected data
+type, such as PLTE, is allowed. If "seq" is not -1, and multiple items
+are allowed for the data type identified in the mask, such as text or
+sPLT, only the n'th item in the structure is freed, where n is "seq".
+
+If you allocated data such as a palette that you passed in to libpng
+with png_set_*, you must not free it until just before the call to
+png_destroy_write_struct().
+
+The default behavior is only to free data that was allocated internally
+by libpng. This can be changed, so that libpng will not free the data,
+or so that it will free data that was allocated by the user with png_malloc()
+or png_calloc() and passed in via a png_set_*() function, with
+
+ png_data_freer(png_ptr, info_ptr, freer, mask)
+
+ freer - one of
+ PNG_DESTROY_WILL_FREE_DATA
+ PNG_SET_WILL_FREE_DATA
+ PNG_USER_WILL_FREE_DATA
+
+ mask - which data elements are affected
+ same choices as in png_free_data()
+
+For example, to transfer responsibility for some data from a read structure
+to a write structure, you could use
+
+ png_data_freer(read_ptr, read_info_ptr,
+ PNG_USER_WILL_FREE_DATA,
+ PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
+
+ png_data_freer(write_ptr, write_info_ptr,
+ PNG_DESTROY_WILL_FREE_DATA,
+ PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
+
+thereby briefly reassigning responsibility for freeing to the user but
+immediately afterwards reassigning it once more to the write_destroy
+function. Having done this, it would then be safe to destroy the read
+structure and continue to use the PLTE, tRNS, and hIST data in the write
+structure.
+
+This function only affects data that has already been allocated.
+You can call this function before calling after the png_set_*() functions
+to control whether the user or png_destroy_*() is supposed to free the data.
+When the user assumes responsibility for libpng-allocated data, the
+application must use
+png_free() to free it, and when the user transfers responsibility to libpng
+for data that the user has allocated, the user must have used png_malloc()
+or png_calloc() to allocate it.
+
+If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
+separately, do not transfer responsibility for freeing text_ptr to libpng,
+because when libpng fills a png_text structure it combines these members with
+the key member, and png_free_data() will free only text_ptr.key. Similarly,
+if you transfer responsibility for free'ing text_ptr from libpng to your
+application, your application must not separately free those members.
+For a more compact example of writing a PNG image, see the file example.c.
+
+V. Simplified API
+
+The simplified API, which became available in libpng-1.6.0, hides the details
+of both libpng and the PNG file format itself.
+It allows PNG files to be read into a very limited number of
+in-memory bitmap formats or to be written from the same formats. If these
+formats do not accommodate your needs then you can, and should, use the more
+sophisticated APIs above - these support a wide variety of in-memory formats
+and a wide variety of sophisticated transformations to those formats as well
+as a wide variety of APIs to manipulate ancilliary information.
+
+To read a PNG file using the simplified API:
+
+ 1) Declare a 'png_image' structure (see below) on the stack, set the
+ version field to PNG_IMAGE_VERSION and the 'opaque' pointer to NULL
+ (this is REQUIRED, your program may crash if you don't do it.)
+
+ 2) Call the appropriate png_image_begin_read... function.
+
+ 3) Set the png_image 'format' member to the required sample format.
+
+ 4) Allocate a buffer for the image and, if required, the color-map.
+
+ 5) Call png_image_finish_read to read the image and, if required, the
+ color-map into your buffers.
+
+There are no restrictions on the format of the PNG input itself; all valid
+color types, bit depths, and interlace methods are acceptable, and the
+input image is transformed as necessary to the requested in-memory format
+during the png_image_finish_read() step. The only caveat is that if you
+request a color-mapped image from a PNG that is full-color or makes
+complex use of an alpha channel the transformation is extremely lossy and the
+result may look terrible.
+
+To write a PNG file using the simplified API:
+
+ 1) Declare a 'png_image' structure on the stack and memset()
+ it to all zero.
+
+ 2) Initialize the members of the structure that describe the
+ image, setting the 'format' member to the format of the
+ image samples.
+
+ 3) Call the appropriate png_image_write... function with a
+ pointer to the image and, if necessary, the color-map to write
+ the PNG data.
+
+png_image is a structure that describes the in-memory format of an image
+when it is being read or defines the in-memory format of an image that you
+need to write. The "png_image" structure contains the following members:
+
+ png_controlp opaque Initialize to NULL, free with png_image_free
+ png_uint_32 version Set to PNG_IMAGE_VERSION
+ png_uint_32 width Image width in pixels (columns)
+ png_uint_32 height Image height in pixels (rows)
+ png_uint_32 format Image format as defined below
+ png_uint_32 flags A bit mask containing informational flags
+ png_uint_32 colormap_entries; Number of entries in the color-map
+ png_uint_32 warning_or_error;
+ char message[64];
+
+In the event of an error or warning the "warning_or_error"
+field will be set to a non-zero value and the 'message' field will contain
+a '\0' terminated string with the libpng error or warning message. If both
+warnings and an error were encountered, only the error is recorded. If there
+are multiple warnings, only the first one is recorded.
+
+The upper 30 bits of the "warning_or_error" value are reserved; the low two
+bits contain a two bit code such that a value more than 1 indicates a failure
+in the API just called:
+
+ 0 - no warning or error
+ 1 - warning
+ 2 - error
+ 3 - error preceded by warning
+
+The pixels (samples) of the image have one to four channels whose components
+have original values in the range 0 to 1.0:
+
+ 1: A single gray or luminance channel (G).
+ 2: A gray/luminance channel and an alpha channel (GA).
+ 3: Three red, green, blue color channels (RGB).
+ 4: Three color channels and an alpha channel (RGBA).
+
+The channels are encoded in one of two ways:
+
+ a) As a small integer, value 0..255, contained in a single byte. For the
+alpha channel the original value is simply value/255. For the color or
+luminance channels the value is encoded according to the sRGB specification
+and matches the 8-bit format expected by typical display devices.
+
+The color/gray channels are not scaled (pre-multiplied) by the alpha
+channel and are suitable for passing to color management software.
+
+ b) As a value in the range 0..65535, contained in a 2-byte integer, in
+the native byte order of the platform on which the application is running.
+All channels can be converted to the original value by dividing by 65535; all
+channels are linear. Color channels use the RGB encoding (RGB end-points) of
+the sRGB specification. This encoding is identified by the
+PNG_FORMAT_FLAG_LINEAR flag below.
+
+When the simplified API needs to convert between sRGB and linear colorspaces,
+the actual sRGB transfer curve defined in the sRGB specification (see the
+article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+approximation used elsewhere in libpng.
+
+When an alpha channel is present it is expected to denote pixel coverage
+of the color or luminance channels and is returned as an associated alpha
+channel: the color/gray channels are scaled (pre-multiplied) by the alpha
+value.
+
+The samples are either contained directly in the image data, between 1 and 8
+bytes per pixel according to the encoding, or are held in a color-map indexed
+by bytes in the image data. In the case of a color-map the color-map entries
+are individual samples, encoded as above, and the image data has one byte per
+pixel to select the relevant sample from the color-map.
+
+PNG_FORMAT_*
+
+The #defines to be used in png_image::format. Each #define identifies a
+particular layout of channel data and, if present, alpha values. There are
+separate defines for each of the two component encodings.
+
+A format is built up using single bit flag values. All combinations are
+valid. Formats can be built up from the flag values or you can use one of
+the predefined values below. When testing formats always use the FORMAT_FLAG
+macros to test for individual features - future versions of the library may
+add new flags.
+
+When reading or writing color-mapped images the format should be set to the
+format of the entries in the color-map then png_image_{read,write}_colormap
+called to read or write the color-map and set the format correctly for the
+image data. Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly!
+
+NOTE: libpng can be built with particular features disabled. If you see
+compiler errors because the definition of one of the following flags has been
+compiled out it is because libpng does not have the required support. It is
+possible, however, for the libpng configuration to enable the format on just
+read or just write; in that case you may see an error at run time.
+You can guard against this by checking for the definition of the
+appropriate "_SUPPORTED" macro, one of:
+
+ PNG_SIMPLIFIED_{READ,WRITE}_{BGR,AFIRST}_SUPPORTED
+
+ PNG_FORMAT_FLAG_ALPHA format with an alpha channel
+ PNG_FORMAT_FLAG_COLOR color format: otherwise grayscale
+ PNG_FORMAT_FLAG_LINEAR 2-byte channels else 1-byte
+ PNG_FORMAT_FLAG_COLORMAP image data is color-mapped
+ PNG_FORMAT_FLAG_BGR BGR colors, else order is RGB
+ PNG_FORMAT_FLAG_AFIRST alpha channel comes first
+
+Supported formats are as follows. Future versions of libpng may support more
+formats; for compatibility with older versions simply check if the format
+macro is defined using #ifdef. These defines describe the in-memory layout
+of the components of the pixels of the image.
+
+First the single byte (sRGB) formats:
+
+ PNG_FORMAT_GRAY
+ PNG_FORMAT_GA
+ PNG_FORMAT_AG
+ PNG_FORMAT_RGB
+ PNG_FORMAT_BGR
+ PNG_FORMAT_RGBA
+ PNG_FORMAT_ARGB
+ PNG_FORMAT_BGRA
+ PNG_FORMAT_ABGR
+
+Then the linear 2-byte formats. When naming these "Y" is used to
+indicate a luminance (gray) channel. The component order within the pixel
+is always the same - there is no provision for swapping the order of the
+components in the linear format. The components are 16-bit integers in
+the native byte order for your platform, and there is no provision for
+swapping the bytes to a different endian condition.
+
+ PNG_FORMAT_LINEAR_Y
+ PNG_FORMAT_LINEAR_Y_ALPHA
+ PNG_FORMAT_LINEAR_RGB
+ PNG_FORMAT_LINEAR_RGB_ALPHA
+
+With color-mapped formats the image data is one byte for each pixel. The byte
+is an index into the color-map which is formatted as above. To obtain a
+color-mapped format it is sufficient just to add the PNG_FOMAT_FLAG_COLORMAP
+to one of the above definitions, or you can use one of the definitions below.
+
+ PNG_FORMAT_RGB_COLORMAP
+ PNG_FORMAT_BGR_COLORMAP
+ PNG_FORMAT_RGBA_COLORMAP
+ PNG_FORMAT_ARGB_COLORMAP
+ PNG_FORMAT_BGRA_COLORMAP
+ PNG_FORMAT_ABGR_COLORMAP
+
+PNG_IMAGE macros
+
+These are convenience macros to derive information from a png_image
+structure. The PNG_IMAGE_SAMPLE_ macros return values appropriate to the
+actual image sample values - either the entries in the color-map or the
+pixels in the image. The PNG_IMAGE_PIXEL_ macros return corresponding values
+for the pixels and will always return 1 for color-mapped formats. The
+remaining macros return information about the rows in the image and the
+complete image.
+
+NOTE: All the macros that take a png_image::format parameter are compile time
+constants if the format parameter is, itself, a constant. Therefore these
+macros can be used in array declarations and case labels where required.
+Similarly the macros are also pre-processor constants (sizeof is not used) so
+they can be used in #if tests.
+
+ PNG_IMAGE_SAMPLE_CHANNELS(fmt)
+ Returns the total number of channels in a given format: 1..4
+
+ PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt)
+ Returns the size in bytes of a single component of a pixel or color-map
+ entry (as appropriate) in the image: 1 or 2.
+
+ PNG_IMAGE_SAMPLE_SIZE(fmt)
+ This is the size of the sample data for one sample. If the image is
+ color-mapped it is the size of one color-map entry (and image pixels are
+ one byte in size), otherwise it is the size of one image pixel.
+
+ PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)
+ The maximum size of the color-map required by the format expressed in a
+ count of components. This can be used to compile-time allocate a
+ color-map:
+
+ png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)];
+
+ png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)];
+
+ Alternatively use the PNG_IMAGE_COLORMAP_SIZE macro below to use the
+ information from one of the png_image_begin_read_ APIs and dynamically
+ allocate the required memory.
+
+ PNG_IMAGE_COLORMAP_SIZE(fmt)
+ The size of the color-map required by the format; this is the size of the
+ color-map buffer passed to the png_image_{read,write}_colormap APIs. It is
+ a fixed number determined by the format so can easily be allocated on the
+ stack if necessary.
+
+Corresponding information about the pixels
+
+ PNG_IMAGE_PIXEL_CHANNELS(fmt)
+ The number of separate channels (components) in a pixel; 1 for a
+ color-mapped image.
+
+ PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)\
+ The size, in bytes, of each component in a pixel; 1 for a color-mapped
+ image.
+
+ PNG_IMAGE_PIXEL_SIZE(fmt)
+ The size, in bytes, of a complete pixel; 1 for a color-mapped image.
+
+Information about the whole row, or whole image
+
+ PNG_IMAGE_ROW_STRIDE(image)
+ Returns the total number of components in a single row of the image; this
+ is the minimum 'row stride', the minimum count of components between each
+ row. For a color-mapped image this is the minimum number of bytes in a
+ row.
+
+ If you need the stride measured in bytes, row_stride_bytes is
+ PNG_IMAGE_ROW_STRIDE(image) * PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)
+ plus any padding bytes that your application might need, for example
+ to start the next row on a 4-byte boundary.
+
+ PNG_IMAGE_BUFFER_SIZE(image, row_stride)
+ Return the size, in bytes, of an image buffer given a png_image and a row
+ stride - the number of components to leave space for in each row.
+
+ PNG_IMAGE_SIZE(image)
+ Return the size, in bytes, of the image in memory given just a png_image;
+ the row stride is the minimum stride required for the image.
+
+ PNG_IMAGE_COLORMAP_SIZE(image)
+ Return the size, in bytes, of the color-map of this image. If the image
+ format is not a color-map format this will return a size sufficient for
+ 256 entries in the given format; check PNG_FORMAT_FLAG_COLORMAP if
+ you don't want to allocate a color-map in this case.
+
+PNG_IMAGE_FLAG_*
+
+Flags containing additional information about the image are held in
+the 'flags' field of png_image.
+
+ PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB == 0x01
+ This indicates the the RGB values of the in-memory bitmap do not
+ correspond to the red, green and blue end-points defined by sRGB.
+
+ PNG_IMAGE_FLAG_FAST == 0x02
+ On write emphasise speed over compression; the resultant PNG file will be
+ larger but will be produced significantly faster, particular for large
+ images. Do not use this option for images which will be distributed, only
+ used it when producing intermediate files that will be read back in
+ repeatedly. For a typical 24-bit image the option will double the read
+ speed at the cost of increasing the image size by 25%, however for many
+ more compressible images the PNG file can be 10 times larger with only a
+ slight speed gain.
+
+ PNG_IMAGE_FLAG_16BIT_sRGB == 0x04
+ On read if the image is a 16-bit per component image and there is no gAMA
+ or sRGB chunk assume that the components are sRGB encoded. Notice that
+ images output by the simplified API always have gamma information; setting
+ this flag only affects the interpretation of 16-bit images from an
+ external source. It is recommended that the application expose this flag
+ to the user; the user can normally easily recognize the difference between
+ linear and sRGB encoding. This flag has no effect on write - the data
+ passed to the write APIs must have the correct encoding (as defined
+ above.)
+
+ If the flag is not set (the default) input 16-bit per component data is
+ assumed to be linear.
+
+ NOTE: the flag can only be set after the png_image_begin_read_ call,
+ because that call initializes the 'flags' field.
+
+READ APIs
+
+ The png_image passed to the read APIs must have been initialized by setting
+ the png_controlp field 'opaque' to NULL (or, better, memset the whole thing.)
+
+ int png_image_begin_read_from_file( png_imagep image,
+ const char *file_name)
+
+ The named file is opened for read and the image header
+ is filled in from the PNG header in the file.
+
+ int png_image_begin_read_from_stdio (png_imagep image,
+ FILE* file)
+
+ The PNG header is read from the stdio FILE object.
+
+ int png_image_begin_read_from_memory(png_imagep image,
+ png_const_voidp memory, png_size_t size)
+
+ The PNG header is read from the given memory buffer.
+
+ int png_image_finish_read(png_imagep image,
+ png_colorp background, void *buffer,
+ png_int_32 row_stride, void *colormap));
+
+ Finish reading the image into the supplied buffer and
+ clean up the png_image structure.
+
+ row_stride is the step, in png_byte or png_uint_16 units
+ as appropriate, between adjacent rows. A positive stride
+ indicates that the top-most row is first in the buffer -
+ the normal top-down arrangement. A negative stride
+ indicates that the bottom-most row is first in the buffer.
+
+ background need only be supplied if an alpha channel must
+ be removed from a png_byte format and the removal is to be
+ done by compositing on a solid color; otherwise it may be
+ NULL and any composition will be done directly onto the
+ buffer. The value is an sRGB color to use for the
+ background, for grayscale output the green channel is used.
+
+ For linear output removing the alpha channel is always done
+ by compositing on black.
+
+ void png_image_free(png_imagep image)
+
+ Free any data allocated by libpng in image->opaque,
+ setting the pointer to NULL. May be called at any time
+ after the structure is initialized.
+
+When the simplified API needs to convert between sRGB and linear colorspaces,
+the actual sRGB transfer curve defined in the sRGB specification (see the
+article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+approximation used elsewhere in libpng.
+
+WRITE APIS
+
+For write you must initialize a png_image structure to describe the image to
+be written:
+
+ version: must be set to PNG_IMAGE_VERSION
+ opaque: must be initialized to NULL
+ width: image width in pixels
+ height: image height in rows
+ format: the format of the data you wish to write
+ flags: set to 0 unless one of the defined flags applies; set
+ PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB for color format images
+ where the RGB values do not correspond to the colors in sRGB.
+ colormap_entries: set to the number of entries in the color-map (0 to 256)
+
+ int png_image_write_to_file, (png_imagep image,
+ const char *file, int convert_to_8bit, const void *buffer,
+ png_int_32 row_stride, const void *colormap));
+
+ Write the image to the named file.
+
+ int png_image_write_to_stdio(png_imagep image, FILE *file,
+ int convert_to_8_bit, const void *buffer,
+ png_int_32 row_stride, const void *colormap)
+
+ Write the image to the given (FILE*).
+
+With all write APIs if image is in one of the linear formats with
+(png_uint_16) data then setting convert_to_8_bit will cause the output to be
+a (png_byte) PNG gamma encoded according to the sRGB specification, otherwise
+a 16-bit linear encoded PNG file is written.
+
+With all APIs row_stride is handled as in the read APIs - it is the spacing
+from one row to the next in component sized units (float) and if negative
+indicates a bottom-up row layout in the buffer. If you pass zero, libpng will
+calculate the row_stride for you from the width and number of channels.
+
+Note that the write API does not support interlacing, sub-8-bit pixels,
+indexed (paletted) images, or most ancillary chunks.
+
+VI. Modifying/Customizing libpng
+
+There are two issues here. The first is changing how libpng does
+standard things like memory allocation, input/output, and error handling.
+The second deals with more complicated things like adding new chunks,
+adding new transformations, and generally changing how libpng works.
+Both of those are compile-time issues; that is, they are generally
+determined at the time the code is written, and there is rarely a need
+to provide the user with a means of changing them.
+
+Memory allocation, input/output, and error handling
+
+All of the memory allocation, input/output, and error handling in libpng
+goes through callbacks that are user-settable. The default routines are
+in pngmem.c, pngrio.c, pngwio.c, and pngerror.c, respectively. To change
+these functions, call the appropriate png_set_*_fn() function.
+
+Memory allocation is done through the functions png_malloc(), png_calloc(),
+and png_free(). The png_malloc() and png_free() functions currently just
+call the standard C functions and png_calloc() calls png_malloc() and then
+clears the newly allocated memory to zero; note that png_calloc(png_ptr, size)
+is not the same as the calloc(number, size) function provided by stdlib.h.
+There is limited support for certain systems with segmented memory
+architectures and the types of pointers declared by png.h match this; you
+will have to use appropriate pointers in your application. If you prefer
+to use a different method of allocating and freeing data, you can use
+png_create_read_struct_2() or png_create_write_struct_2() to register your
+own functions as described above. These functions also provide a void
+pointer that can be retrieved via
+
+ mem_ptr=png_get_mem_ptr(png_ptr);
+
+Your replacement memory functions must have prototypes as follows:
+
+ png_voidp malloc_fn(png_structp png_ptr,
+ png_alloc_size_t size);
+
+ void free_fn(png_structp png_ptr, png_voidp ptr);
+
+Your malloc_fn() must return NULL in case of failure. The png_malloc()
+function will normally call png_error() if it receives a NULL from the
+system memory allocator or from your replacement malloc_fn().
+
+Your free_fn() will never be called with a NULL ptr, since libpng's
+png_free() checks for NULL before calling free_fn().
+
+Input/Output in libpng is done through png_read() and png_write(),
+which currently just call fread() and fwrite(). The FILE * is stored in
+png_struct and is initialized via png_init_io(). If you wish to change
+the method of I/O, the library supplies callbacks that you can set
+through the function png_set_read_fn() and png_set_write_fn() at run
+time, instead of calling the png_init_io() function. These functions
+also provide a void pointer that can be retrieved via the function
+png_get_io_ptr(). For example:
+
+ png_set_read_fn(png_structp read_ptr,
+ voidp read_io_ptr, png_rw_ptr read_data_fn)
+
+ png_set_write_fn(png_structp write_ptr,
+ voidp write_io_ptr, png_rw_ptr write_data_fn,
+ png_flush_ptr output_flush_fn);
+
+ voidp read_io_ptr = png_get_io_ptr(read_ptr);
+ voidp write_io_ptr = png_get_io_ptr(write_ptr);
+
+The replacement I/O functions must have prototypes as follows:
+
+ void user_read_data(png_structp png_ptr,
+ png_bytep data, png_size_t length);
+
+ void user_write_data(png_structp png_ptr,
+ png_bytep data, png_size_t length);
+
+ void user_flush_data(png_structp png_ptr);
+
+The user_read_data() function is responsible for detecting and
+handling end-of-data errors.
+
+Supplying NULL for the read, write, or flush functions sets them back
+to using the default C stream functions, which expect the io_ptr to
+point to a standard *FILE structure. It is probably a mistake
+to use NULL for one of write_data_fn and output_flush_fn but not both
+of them, unless you have built libpng with PNG_NO_WRITE_FLUSH defined.
+It is an error to read from a write stream, and vice versa.
+
+Error handling in libpng is done through png_error() and png_warning().
+Errors handled through png_error() are fatal, meaning that png_error()
+should never return to its caller. Currently, this is handled via
+setjmp() and longjmp() (unless you have compiled libpng with
+PNG_NO_SETJMP, in which case it is handled via PNG_ABORT()),
+but you could change this to do things like exit() if you should wish,
+as long as your function does not return.
+
+On non-fatal errors, png_warning() is called
+to print a warning message, and then control returns to the calling code.
+By default png_error() and png_warning() print a message on stderr via
+fprintf() unless the library is compiled with PNG_NO_CONSOLE_IO defined
+(because you don't want the messages) or PNG_NO_STDIO defined (because
+fprintf() isn't available). If you wish to change the behavior of the error
+functions, you will need to set up your own message callbacks. These
+functions are normally supplied at the time that the png_struct is created.
+It is also possible to redirect errors and warnings to your own replacement
+functions after png_create_*_struct() has been called by calling:
+
+ png_set_error_fn(png_structp png_ptr,
+ png_voidp error_ptr, png_error_ptr error_fn,
+ png_error_ptr warning_fn);
+
+ png_voidp error_ptr = png_get_error_ptr(png_ptr);
+
+If NULL is supplied for either error_fn or warning_fn, then the libpng
+default function will be used, calling fprintf() and/or longjmp() if a
+problem is encountered. The replacement error functions should have
+parameters as follows:
+
+ void user_error_fn(png_structp png_ptr,
+ png_const_charp error_msg);
+
+ void user_warning_fn(png_structp png_ptr,
+ png_const_charp warning_msg);
+
+The motivation behind using setjmp() and longjmp() is the C++ throw and
+catch exception handling methods. This makes the code much easier to write,
+as there is no need to check every return code of every function call.
+However, there are some uncertainties about the status of local variables
+after a longjmp, so the user may want to be careful about doing anything
+after setjmp returns non-zero besides returning itself. Consult your
+compiler documentation for more details. For an alternative approach, you
+may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net),
+which is illustrated in pngvalid.c and in contrib/visupng.
+
+Beginning in libpng-1.4.0, the png_set_benign_errors() API became available.
+You can use this to handle certain errors (normally handled as errors)
+as warnings.
+
+ png_set_benign_errors (png_ptr, int allowed);
+
+ allowed: 0: treat png_benign_error() as an error.
+ 1: treat png_benign_error() as a warning.
+
+As of libpng-1.6.0, the default condition is to treat benign errors as
+warnings while reading and as errors while writing.
+
+Custom chunks
+
+If you need to read or write custom chunks, you may need to get deeper
+into the libpng code. The library now has mechanisms for storing
+and writing chunks of unknown type; you can even declare callbacks
+for custom chunks. However, this may not be good enough if the
+library code itself needs to know about interactions between your
+chunk and existing `intrinsic' chunks.
+
+If you need to write a new intrinsic chunk, first read the PNG
+specification. Acquire a first level of understanding of how it works.
+Pay particular attention to the sections that describe chunk names,
+and look at how other chunks were designed, so you can do things
+similarly. Second, check out the sections of libpng that read and
+write chunks. Try to find a chunk that is similar to yours and use
+it as a template. More details can be found in the comments inside
+the code. It is best to handle private or unknown chunks in a generic method,
+via callback functions, instead of by modifying libpng functions. This
+is illustrated in pngtest.c, which uses a callback function to handle a
+private "vpAg" chunk and the new "sTER" chunk, which are both unknown to
+libpng.
+
+If you wish to write your own transformation for the data, look through
+the part of the code that does the transformations, and check out some of
+the simpler ones to get an idea of how they work. Try to find a similar
+transformation to the one you want to add and copy off of it. More details
+can be found in the comments inside the code itself.
+
+Configuring for gui/windowing platforms:
+
+You will need to write new error and warning functions that use the GUI
+interface, as described previously, and set them to be the error and
+warning functions at the time that png_create_*_struct() is called,
+in order to have them available during the structure initialization.
+They can be changed later via png_set_error_fn(). On some compilers,
+you may also have to change the memory allocators (png_malloc, etc.).
+
+Configuring zlib:
+
+There are special functions to configure the compression. Perhaps the
+most useful one changes the compression level, which currently uses
+input compression values in the range 0 - 9. The library normally
+uses the default compression level (Z_DEFAULT_COMPRESSION = 6). Tests
+have shown that for a large majority of images, compression values in
+the range 3-6 compress nearly as well as higher levels, and do so much
+faster. For online applications it may be desirable to have maximum speed
+(Z_BEST_SPEED = 1). With versions of zlib after v0.99, you can also
+specify no compression (Z_NO_COMPRESSION = 0), but this would create
+files larger than just storing the raw bitmap. You can specify the
+compression level by calling:
+
+ #include zlib.h
+ png_set_compression_level(png_ptr, level);
+
+Another useful one is to reduce the memory level used by the library.
+The memory level defaults to 8, but it can be lowered if you are
+short on memory (running DOS, for example, where you only have 640K).
+Note that the memory level does have an effect on compression; among
+other things, lower levels will result in sections of incompressible
+data being emitted in smaller stored blocks, with a correspondingly
+larger relative overhead of up to 15% in the worst case.
+
+ #include zlib.h
+ png_set_compression_mem_level(png_ptr, level);
+
+The other functions are for configuring zlib. They are not recommended
+for normal use and may result in writing an invalid PNG file. See
+zlib.h for more information on what these mean.
+
+ #include zlib.h
+ png_set_compression_strategy(png_ptr,
+ strategy);
+
+ png_set_compression_window_bits(png_ptr,
+ window_bits);
+
+ png_set_compression_method(png_ptr, method);
+
+This controls the size of the IDAT chunks (default 8192):
+
+ png_set_compression_buffer_size(png_ptr, size);
+
+As of libpng version 1.5.4, additional APIs became
+available to set these separately for non-IDAT
+compressed chunks such as zTXt, iTXt, and iCCP:
+
+ #include zlib.h
+ #if PNG_LIBPNG_VER >= 10504
+ png_set_text_compression_level(png_ptr, level);
+
+ png_set_text_compression_mem_level(png_ptr, level);
+
+ png_set_text_compression_strategy(png_ptr,
+ strategy);
+
+ png_set_text_compression_window_bits(png_ptr,
+ window_bits);
+
+ png_set_text_compression_method(png_ptr, method);
+ #endif
+
+Controlling row filtering
+
+If you want to control whether libpng uses filtering or not, which
+filters are used, and how it goes about picking row filters, you
+can call one of these functions. The selection and configuration
+of row filters can have a significant impact on the size and
+encoding speed and a somewhat lesser impact on the decoding speed
+of an image. Filtering is enabled by default for RGB and grayscale
+images (with and without alpha), but not for paletted images nor
+for any images with bit depths less than 8 bits/pixel.
+
+The 'method' parameter sets the main filtering method, which is
+currently only '0' in the PNG 1.2 specification. The 'filters'
+parameter sets which filter(s), if any, should be used for each
+scanline. Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS
+to turn filtering on and off, respectively.
+
+Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB,
+PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise
+ORed together with '|' to specify one or more filters to use.
+These filters are described in more detail in the PNG specification.
+If you intend to change the filter type during the course of writing
+the image, you should start with flags set for all of the filters
+you intend to use so that libpng can initialize its internal
+structures appropriately for all of the filter types. (Note that this
+means the first row must always be adaptively filtered, because libpng
+currently does not allocate the filter buffers until png_write_row()
+is called for the first time.)
+
+ filters = PNG_FILTER_NONE | PNG_FILTER_SUB
+ PNG_FILTER_UP | PNG_FILTER_AVG |
+ PNG_FILTER_PAETH | PNG_ALL_FILTERS;
+
+ png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE,
+ filters);
+ The second parameter can also be
+ PNG_INTRAPIXEL_DIFFERENCING if you are
+ writing a PNG to be embedded in a MNG
+ datastream. This parameter must be the
+ same as the value of filter_method used
+ in png_set_IHDR().
+
+Requesting debug printout
+
+The macro definition PNG_DEBUG can be used to request debugging
+printout. Set it to an integer value in the range 0 to 3. Higher
+numbers result in increasing amounts of debugging information. The
+information is printed to the "stderr" file, unless another file
+name is specified in the PNG_DEBUG_FILE macro definition.
+
+When PNG_DEBUG > 0, the following functions (macros) become available:
+
+ png_debug(level, message)
+ png_debug1(level, message, p1)
+ png_debug2(level, message, p1, p2)
+
+in which "level" is compared to PNG_DEBUG to decide whether to print
+the message, "message" is the formatted string to be printed,
+and p1 and p2 are parameters that are to be embedded in the string
+according to printf-style formatting directives. For example,
+
+ png_debug1(2, "foo=%d", foo);
+
+is expanded to
+
+ if (PNG_DEBUG > 2)
+ fprintf(PNG_DEBUG_FILE, "foo=%d\n", foo);
+
+When PNG_DEBUG is defined but is zero, the macros aren't defined, but you
+can still use PNG_DEBUG to control your own debugging:
+
+ #ifdef PNG_DEBUG
+ fprintf(stderr, ...
+ #endif
+
+When PNG_DEBUG = 1, the macros are defined, but only png_debug statements
+having level = 0 will be printed. There aren't any such statements in
+this version of libpng, but if you insert some they will be printed.
+
+VII. MNG support
+
+The MNG specification (available at http://www.libpng.org/pub/mng) allows
+certain extensions to PNG for PNG images that are embedded in MNG datastreams.
+Libpng can support some of these extensions. To enable them, use the
+png_permit_mng_features() function:
+
+ feature_set = png_permit_mng_features(png_ptr, mask)
+
+ mask is a png_uint_32 containing the bitwise OR of the
+ features you want to enable. These include
+ PNG_FLAG_MNG_EMPTY_PLTE
+ PNG_FLAG_MNG_FILTER_64
+ PNG_ALL_MNG_FEATURES
+
+ feature_set is a png_uint_32 that is the bitwise AND of
+ your mask with the set of MNG features that is
+ supported by the version of libpng that you are using.
+
+It is an error to use this function when reading or writing a standalone
+PNG file with the PNG 8-byte signature. The PNG datastream must be wrapped
+in a MNG datastream. As a minimum, it must have the MNG 8-byte signature
+and the MHDR and MEND chunks. Libpng does not provide support for these
+or any other MNG chunks; your application must provide its own support for
+them. You may wish to consider using libmng (available at
+http://www.libmng.com) instead.
+
+VIII. Changes to Libpng from version 0.88
+
+It should be noted that versions of libpng later than 0.96 are not
+distributed by the original libpng author, Guy Schalnat, nor by
+Andreas Dilger, who had taken over from Guy during 1996 and 1997, and
+distributed versions 0.89 through 0.96, but rather by another member
+of the original PNG Group, Glenn Randers-Pehrson. Guy and Andreas are
+still alive and well, but they have moved on to other things.
+
+The old libpng functions png_read_init(), png_write_init(),
+png_info_init(), png_read_destroy(), and png_write_destroy() have been
+moved to PNG_INTERNAL in version 0.95 to discourage their use. These
+functions will be removed from libpng version 1.4.0.
+
+The preferred method of creating and initializing the libpng structures is
+via the png_create_read_struct(), png_create_write_struct(), and
+png_create_info_struct() because they isolate the size of the structures
+from the application, allow version error checking, and also allow the
+use of custom error handling routines during the initialization, which
+the old functions do not. The functions png_read_destroy() and
+png_write_destroy() do not actually free the memory that libpng
+allocated for these structs, but just reset the data structures, so they
+can be used instead of png_destroy_read_struct() and
+png_destroy_write_struct() if you feel there is too much system overhead
+allocating and freeing the png_struct for each image read.
+
+Setting the error callbacks via png_set_message_fn() before
+png_read_init() as was suggested in libpng-0.88 is no longer supported
+because this caused applications that do not use custom error functions
+to fail if the png_ptr was not initialized to zero. It is still possible
+to set the error callbacks AFTER png_read_init(), or to change them with
+png_set_error_fn(), which is essentially the same function, but with a new
+name to force compilation errors with applications that try to use the old
+method.
+
+Support for the sCAL, iCCP, iTXt, and sPLT chunks was added at libpng-1.0.6;
+however, iTXt support was not enabled by default.
+
+Starting with version 1.0.7, you can find out which version of the library
+you are using at run-time:
+
+ png_uint_32 libpng_vn = png_access_version_number();
+
+The number libpng_vn is constructed from the major version, minor
+version with leading zero, and release number with leading zero,
+(e.g., libpng_vn for version 1.0.7 is 10007).
+
+Note that this function does not take a png_ptr, so you can call it
+before you've created one.
+
+You can also check which version of png.h you used when compiling your
+application:
+
+ png_uint_32 application_vn = PNG_LIBPNG_VER;
+
+IX. Changes to Libpng from version 1.0.x to 1.2.x
+
+Support for user memory management was enabled by default. To
+accomplish this, the functions png_create_read_struct_2(),
+png_create_write_struct_2(), png_set_mem_fn(), png_get_mem_ptr(),
+png_malloc_default(), and png_free_default() were added.
+
+Support for the iTXt chunk has been enabled by default as of
+version 1.2.41.
+
+Support for certain MNG features was enabled.
+
+Support for numbered error messages was added. However, we never got
+around to actually numbering the error messages. The function
+png_set_strip_error_numbers() was added (Note: the prototype for this
+function was inadvertently removed from png.h in PNG_NO_ASSEMBLER_CODE
+builds of libpng-1.2.15. It was restored in libpng-1.2.36).
+
+The png_malloc_warn() function was added at libpng-1.2.3. This issues
+a png_warning and returns NULL instead of aborting when it fails to
+acquire the requested memory allocation.
+
+Support for setting user limits on image width and height was enabled
+by default. The functions png_set_user_limits(), png_get_user_width_max(),
+and png_get_user_height_max() were added at libpng-1.2.6.
+
+The png_set_add_alpha() function was added at libpng-1.2.7.
+
+The function png_set_expand_gray_1_2_4_to_8() was added at libpng-1.2.9.
+Unlike png_set_gray_1_2_4_to_8(), the new function does not expand the
+tRNS chunk to alpha. The png_set_gray_1_2_4_to_8() function is
+deprecated.
+
+A number of macro definitions in support of runtime selection of
+assembler code features (especially Intel MMX code support) were
+added at libpng-1.2.0:
+
+ PNG_ASM_FLAG_MMX_SUPPORT_COMPILED
+ PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU
+ PNG_ASM_FLAG_MMX_READ_COMBINE_ROW
+ PNG_ASM_FLAG_MMX_READ_INTERLACE
+ PNG_ASM_FLAG_MMX_READ_FILTER_SUB
+ PNG_ASM_FLAG_MMX_READ_FILTER_UP
+ PNG_ASM_FLAG_MMX_READ_FILTER_AVG
+ PNG_ASM_FLAG_MMX_READ_FILTER_PAETH
+ PNG_ASM_FLAGS_INITIALIZED
+ PNG_MMX_READ_FLAGS
+ PNG_MMX_FLAGS
+ PNG_MMX_WRITE_FLAGS
+ PNG_MMX_FLAGS
+
+We added the following functions in support of runtime
+selection of assembler code features:
+
+ png_get_mmx_flagmask()
+ png_set_mmx_thresholds()
+ png_get_asm_flags()
+ png_get_mmx_bitdepth_threshold()
+ png_get_mmx_rowbytes_threshold()
+ png_set_asm_flags()
+
+We replaced all of these functions with simple stubs in libpng-1.2.20,
+when the Intel assembler code was removed due to a licensing issue.
+
+These macros are deprecated:
+
+ PNG_READ_TRANSFORMS_NOT_SUPPORTED
+ PNG_PROGRESSIVE_READ_NOT_SUPPORTED
+ PNG_NO_SEQUENTIAL_READ_SUPPORTED
+ PNG_WRITE_TRANSFORMS_NOT_SUPPORTED
+ PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED
+ PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED
+
+They have been replaced, respectively, by:
+
+ PNG_NO_READ_TRANSFORMS
+ PNG_NO_PROGRESSIVE_READ
+ PNG_NO_SEQUENTIAL_READ
+ PNG_NO_WRITE_TRANSFORMS
+ PNG_NO_READ_ANCILLARY_CHUNKS
+ PNG_NO_WRITE_ANCILLARY_CHUNKS
+
+PNG_MAX_UINT was replaced with PNG_UINT_31_MAX. It has been
+deprecated since libpng-1.0.16 and libpng-1.2.6.
+
+The function
+ png_check_sig(sig, num)
+was replaced with
+ !png_sig_cmp(sig, 0, num)
+It has been deprecated since libpng-0.90.
+
+The function
+ png_set_gray_1_2_4_to_8()
+which also expands tRNS to alpha was replaced with
+ png_set_expand_gray_1_2_4_to_8()
+which does not. It has been deprecated since libpng-1.0.18 and 1.2.9.
+
+X. Changes to Libpng from version 1.0.x/1.2.x to 1.4.x
+
+Private libpng prototypes and macro definitions were moved from
+png.h and pngconf.h into a new pngpriv.h header file.
+
+Functions png_set_benign_errors(), png_benign_error(), and
+png_chunk_benign_error() were added.
+
+Support for setting the maximum amount of memory that the application
+will allocate for reading chunks was added, as a security measure.
+The functions png_set_chunk_cache_max() and png_get_chunk_cache_max()
+were added to the library.
+
+We implemented support for I/O states by adding png_ptr member io_state
+and functions png_get_io_chunk_name() and png_get_io_state() in pngget.c
+
+We added PNG_TRANSFORM_GRAY_TO_RGB to the available high-level
+input transforms.
+
+Checking for and reporting of errors in the IHDR chunk is more thorough.
+
+Support for global arrays was removed, to improve thread safety.
+
+Some obsolete/deprecated macros and functions have been removed.
+
+Typecasted NULL definitions such as
+ #define png_voidp_NULL (png_voidp)NULL
+were eliminated. If you used these in your application, just use
+NULL instead.
+
+The png_struct and info_struct members "trans" and "trans_values" were
+changed to "trans_alpha" and "trans_color", respectively.
+
+The obsolete, unused pnggccrd.c and pngvcrd.c files and related makefiles
+were removed.
+
+The PNG_1_0_X and PNG_1_2_X macros were eliminated.
+
+The PNG_LEGACY_SUPPORTED macro was eliminated.
+
+Many WIN32_WCE #ifdefs were removed.
+
+The functions png_read_init(info_ptr), png_write_init(info_ptr),
+png_info_init(info_ptr), png_read_destroy(), and png_write_destroy()
+have been removed. They have been deprecated since libpng-0.95.
+
+The png_permit_empty_plte() was removed. It has been deprecated
+since libpng-1.0.9. Use png_permit_mng_features() instead.
+
+We removed the obsolete stub functions png_get_mmx_flagmask(),
+png_set_mmx_thresholds(), png_get_asm_flags(),
+png_get_mmx_bitdepth_threshold(), png_get_mmx_rowbytes_threshold(),
+png_set_asm_flags(), and png_mmx_supported()
+
+We removed the obsolete png_check_sig(), png_memcpy_check(), and
+png_memset_check() functions. Instead use !png_sig_cmp(), memcpy(),
+and memset(), respectively.
+
+The function png_set_gray_1_2_4_to_8() was removed. It has been
+deprecated since libpng-1.0.18 and 1.2.9, when it was replaced with
+png_set_expand_gray_1_2_4_to_8() because the former function also
+expanded any tRNS chunk to an alpha channel.
+
+Macros for png_get_uint_16, png_get_uint_32, and png_get_int_32
+were added and are used by default instead of the corresponding
+functions. Unfortunately,
+from libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
+function) incorrectly returned a value of type png_uint_32.
+
+We changed the prototype for png_malloc() from
+ png_malloc(png_structp png_ptr, png_uint_32 size)
+to
+ png_malloc(png_structp png_ptr, png_alloc_size_t size)
+
+This also applies to the prototype for the user replacement malloc_fn().
+
+The png_calloc() function was added and is used in place of
+of "png_malloc(); memset();" except in the case in png_read_png()
+where the array consists of pointers; in this case a "for" loop is used
+after the png_malloc() to set the pointers to NULL, to give robust.
+behavior in case the application runs out of memory part-way through
+the process.
+
+We changed the prototypes of png_get_compression_buffer_size() and
+png_set_compression_buffer_size() to work with png_size_t instead of
+png_uint_32.
+
+Support for numbered error messages was removed by default, since we
+never got around to actually numbering the error messages. The function
+png_set_strip_error_numbers() was removed from the library by default.
+
+The png_zalloc() and png_zfree() functions are no longer exported.
+The png_zalloc() function no longer zeroes out the memory that it
+allocates. Applications that called png_zalloc(png_ptr, number, size)
+can call png_calloc(png_ptr, number*size) instead, and can call
+png_free() instead of png_zfree().
+
+Support for dithering was disabled by default in libpng-1.4.0, because
+it has not been well tested and doesn't actually "dither".
+The code was not
+removed, however, and could be enabled by building libpng with
+PNG_READ_DITHER_SUPPORTED defined. In libpng-1.4.2, this support
+was re-enabled, but the function was renamed png_set_quantize() to
+reflect more accurately what it actually does. At the same time,
+the PNG_DITHER_[RED,GREEN_BLUE]_BITS macros were also renamed to
+PNG_QUANTIZE_[RED,GREEN,BLUE]_BITS, and PNG_READ_DITHER_SUPPORTED
+was renamed to PNG_READ_QUANTIZE_SUPPORTED.
+
+We removed the trailing '.' from the warning and error messages.
+
+XI. Changes to Libpng from version 1.4.x to 1.5.x
+
+From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
+function) incorrectly returned a value of type png_uint_32.
+The incorrect macro was removed from libpng-1.4.5.
+
+Checking for invalid palette index on write was added at libpng
+1.5.10. If a pixel contains an invalid (out-of-range) index libpng issues
+a benign error. This is enabled by default because this condition is an
+error according to the PNG specification, Clause 11.3.2, but the error can
+be ignored in each png_ptr with
+
+ png_set_check_for_invalid_index(png_ptr, allowed);
+
+ allowed - one of
+ 0: disable benign error (accept the
+ invalid data without warning).
+ 1: enable benign error (treat the
+ invalid data as an error or a
+ warning).
+
+If the error is ignored, or if png_benign_error() treats it as a warning,
+any invalid pixels are decoded as opaque black by the decoder and written
+as-is by the encoder.
+
+Retrieving the maximum palette index found was added at libpng-1.5.15.
+This statement must appear after png_read_png() or png_read_image() while
+reading, and after png_write_png() or png_write_image() while writing.
+
+ int max_palette = png_get_palette_max(png_ptr, info_ptr);
+
+This will return the maximum palette index found in the image, or "-1" if
+the palette was not checked, or "0" if no palette was found. Note that this
+does not account for any palette index used by ancillary chunks such as the
+bKGD chunk; you must check those separately to determine the maximum
+palette index actually used.
+
+There are no substantial API changes between the non-deprecated parts of
+the 1.4.5 API and the 1.5.0 API; however, the ability to directly access
+members of the main libpng control structures, png_struct and png_info,
+deprecated in earlier versions of libpng, has been completely removed from
+libpng 1.5.
+
+We no longer include zlib.h in png.h. The include statement has been moved
+to pngstruct.h, where it is not accessible by applications. Applications that
+need access to information in zlib.h will need to add the '#include "zlib.h"'
+directive. It does not matter whether this is placed prior to or after
+the '"#include png.h"' directive.
+
+The png_sprintf(), png_strcpy(), and png_strncpy() macros are no longer used
+and were removed.
+
+We moved the png_strlen(), png_memcpy(), png_memset(), and png_memcmp()
+macros into a private header file (pngpriv.h) that is not accessible to
+applications.
+
+In png_get_iCCP, the type of "profile" was changed from png_charpp
+to png_bytepp, and in png_set_iCCP, from png_charp to png_const_bytep.
+
+There are changes of form in png.h, including new and changed macros to
+declare parts of the API. Some API functions with arguments that are
+pointers to data not modified within the function have been corrected to
+declare these arguments with PNG_CONST.
+
+Much of the internal use of C macros to control the library build has also
+changed and some of this is visible in the exported header files, in
+particular the use of macros to control data and API elements visible
+during application compilation may require significant revision to
+application code. (It is extremely rare for an application to do this.)
+
+Any program that compiled against libpng 1.4 and did not use deprecated
+features or access internal library structures should compile and work
+against libpng 1.5, except for the change in the prototype for
+png_get_iCCP() and png_set_iCCP() API functions mentioned above.
+
+libpng 1.5.0 adds PNG_ PASS macros to help in the reading and writing of
+interlaced images. The macros return the number of rows and columns in
+each pass and information that can be used to de-interlace and (if
+absolutely necessary) interlace an image.
+
+libpng 1.5.0 adds an API png_longjmp(png_ptr, value). This API calls
+the application-provided png_longjmp_ptr on the internal, but application
+initialized, longjmp buffer. It is provided as a convenience to avoid
+the need to use the png_jmpbuf macro, which had the unnecessary side
+effect of resetting the internal png_longjmp_ptr value.
+
+libpng 1.5.0 includes a complete fixed point API. By default this is
+present along with the corresponding floating point API. In general the
+fixed point API is faster and smaller than the floating point one because
+the PNG file format used fixed point, not floating point. This applies
+even if the library uses floating point in internal calculations. A new
+macro, PNG_FLOATING_ARITHMETIC_SUPPORTED, reveals whether the library
+uses floating point arithmetic (the default) or fixed point arithmetic
+internally for performance critical calculations such as gamma correction.
+In some cases, the gamma calculations may produce slightly different
+results. This has changed the results in png_rgb_to_gray and in alpha
+composition (png_set_background for example). This applies even if the
+original image was already linear (gamma == 1.0) and, therefore, it is
+not necessary to linearize the image. This is because libpng has *not*
+been changed to optimize that case correctly, yet.
+
+Fixed point support for the sCAL chunk comes with an important caveat;
+the sCAL specification uses a decimal encoding of floating point values
+and the accuracy of PNG fixed point values is insufficient for
+representation of these values. Consequently a "string" API
+(png_get_sCAL_s and png_set_sCAL_s) is the only reliable way of reading
+arbitrary sCAL chunks in the absence of either the floating point API or
+internal floating point calculations. Starting with libpng-1.5.0, both
+of these functions are present when PNG_sCAL_SUPPORTED is defined. Prior
+to libpng-1.5.0, their presence also depended upon PNG_FIXED_POINT_SUPPORTED
+being defined and PNG_FLOATING_POINT_SUPPORTED not being defined.
+
+Applications no longer need to include the optional distribution header
+file pngusr.h or define the corresponding macros during application
+build in order to see the correct variant of the libpng API. From 1.5.0
+application code can check for the corresponding _SUPPORTED macro:
+
+#ifdef PNG_INCH_CONVERSIONS_SUPPORTED
+ /* code that uses the inch conversion APIs. */
+#endif
+
+This macro will only be defined if the inch conversion functions have been
+compiled into libpng. The full set of macros, and whether or not support
+has been compiled in, are available in the header file pnglibconf.h.
+This header file is specific to the libpng build. Notice that prior to
+1.5.0 the _SUPPORTED macros would always have the default definition unless
+reset by pngusr.h or by explicit settings on the compiler command line.
+These settings may produce compiler warnings or errors in 1.5.0 because
+of macro redefinition.
+
+Applications can now choose whether to use these macros or to call the
+corresponding function by defining PNG_USE_READ_MACROS or
+PNG_NO_USE_READ_MACROS before including png.h. Notice that this is
+only supported from 1.5.0; defining PNG_NO_USE_READ_MACROS prior to 1.5.0
+will lead to a link failure.
+
+Prior to libpng-1.5.4, the zlib compressor used the same set of parameters
+when compressing the IDAT data and textual data such as zTXt and iCCP.
+In libpng-1.5.4 we reinitialized the zlib stream for each type of data.
+We added five png_set_text_*() functions for setting the parameters to
+use with textual data.
+
+Prior to libpng-1.5.4, the PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
+option was off by default, and slightly inaccurate scaling occurred.
+This option can no longer be turned off, and the choice of accurate
+or inaccurate 16-to-8 scaling is by using the new png_set_scale_16_to_8()
+API for accurate scaling or the old png_set_strip_16_to_8() API for simple
+chopping. In libpng-1.5.4, the PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
+macro became PNG_READ_SCALE_16_TO_8_SUPPORTED, and the PNG_READ_16_TO_8
+macro became PNG_READ_STRIP_16_TO_8_SUPPORTED, to enable the two
+png_set_*_16_to_8() functions separately.
+
+Prior to libpng-1.5.4, the png_set_user_limits() function could only be
+used to reduce the width and height limits from the value of
+PNG_USER_WIDTH_MAX and PNG_USER_HEIGHT_MAX, although this document said
+that it could be used to override them. Now this function will reduce or
+increase the limits.
+
+Starting in libpng-1.5.10, the user limits can be set en masse with the
+configuration option PNG_SAFE_LIMITS_SUPPORTED. If this option is enabled,
+a set of "safe" limits is applied in pngpriv.h. These can be overridden by
+application calls to png_set_user_limits(), png_set_user_chunk_cache_max(),
+and/or png_set_user_malloc_max() that increase or decrease the limits. Also,
+in libpng-1.5.10 the default width and height limits were increased
+from 1,000,000 to 0x7fffffff (i.e., made unlimited). Therefore, the
+limits are now
+ default safe
+ png_user_width_max 0x7fffffff 1,000,000
+ png_user_height_max 0x7fffffff 1,000,000
+ png_user_chunk_cache_max 0 (unlimited) 128
+ png_user_chunk_malloc_max 0 (unlimited) 8,000,000
+
+The png_set_option() function (and the "options" member of the png struct) was
+added to libpng-1.5.15, with option PNG_ARM_NEON.
+
+The library now supports a complete fixed point implementation and can
+thus be used on systems that have no floating point support or very
+limited or slow support. Previously gamma correction, an essential part
+of complete PNG support, required reasonably fast floating point.
+
+As part of this the choice of internal implementation has been made
+independent of the choice of fixed versus floating point APIs and all the
+missing fixed point APIs have been implemented.
+
+The exact mechanism used to control attributes of API functions has
+changed, as described in the INSTALL file.
+
+A new test program, pngvalid, is provided in addition to pngtest.
+pngvalid validates the arithmetic accuracy of the gamma correction
+calculations and includes a number of validations of the file format.
+A subset of the full range of tests is run when "make check" is done
+(in the 'configure' build.) pngvalid also allows total allocated memory
+usage to be evaluated and performs additional memory overwrite validation.
+
+Many changes to individual feature macros have been made. The following
+are the changes most likely to be noticed by library builders who
+configure libpng:
+
+1) All feature macros now have consistent naming:
+
+#define PNG_NO_feature turns the feature off
+#define PNG_feature_SUPPORTED turns the feature on
+
+pnglibconf.h contains one line for each feature macro which is either:
+
+#define PNG_feature_SUPPORTED
+
+if the feature is supported or:
+
+/*#undef PNG_feature_SUPPORTED*/
+
+if it is not. Library code consistently checks for the 'SUPPORTED' macro.
+It does not, and libpng applications should not, check for the 'NO' macro
+which will not normally be defined even if the feature is not supported.
+The 'NO' macros are only used internally for setting or not setting the
+corresponding 'SUPPORTED' macros.
+
+Compatibility with the old names is provided as follows:
+
+PNG_INCH_CONVERSIONS turns on PNG_INCH_CONVERSIONS_SUPPORTED
+
+And the following definitions disable the corresponding feature:
+
+PNG_SETJMP_NOT_SUPPORTED disables SETJMP
+PNG_READ_TRANSFORMS_NOT_SUPPORTED disables READ_TRANSFORMS
+PNG_NO_READ_COMPOSITED_NODIV disables READ_COMPOSITE_NODIV
+PNG_WRITE_TRANSFORMS_NOT_SUPPORTED disables WRITE_TRANSFORMS
+PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED disables READ_ANCILLARY_CHUNKS
+PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED disables WRITE_ANCILLARY_CHUNKS
+
+Library builders should remove use of the above, inconsistent, names.
+
+2) Warning and error message formatting was previously conditional on
+the STDIO feature. The library has been changed to use the
+CONSOLE_IO feature instead. This means that if CONSOLE_IO is disabled
+the library no longer uses the printf(3) functions, even though the
+default read/write implementations use (FILE) style stdio.h functions.
+
+3) Three feature macros now control the fixed/floating point decisions:
+
+PNG_FLOATING_POINT_SUPPORTED enables the floating point APIs
+
+PNG_FIXED_POINT_SUPPORTED enables the fixed point APIs; however, in
+practice these are normally required internally anyway (because the PNG
+file format is fixed point), therefore in most cases PNG_NO_FIXED_POINT
+merely stops the function from being exported.
+
+PNG_FLOATING_ARITHMETIC_SUPPORTED chooses between the internal floating
+point implementation or the fixed point one. Typically the fixed point
+implementation is larger and slower than the floating point implementation
+on a system that supports floating point; however, it may be faster on a
+system which lacks floating point hardware and therefore uses a software
+emulation.
+
+4) Added PNG_{READ,WRITE}_INT_FUNCTIONS_SUPPORTED. This allows the
+functions to read and write ints to be disabled independently of
+PNG_USE_READ_MACROS, which allows libpng to be built with the functions
+even though the default is to use the macros - this allows applications
+to choose at app buildtime whether or not to use macros (previously
+impossible because the functions weren't in the default build.)
+
+XII. Changes to Libpng from version 1.5.x to 1.6.x
+
+A "simplified API" has been added (see documentation in png.h and a simple
+example in contrib/examples/pngtopng.c). The new publicly visible API
+includes the following:
+
+ macros:
+ PNG_FORMAT_*
+ PNG_IMAGE_*
+ structures:
+ png_control
+ png_image
+ read functions
+ png_image_begin_read_from_file()
+ png_image_begin_read_from_stdio()
+ png_image_begin_read_from_memory()
+ png_image_finish_read()
+ png_image_free()
+ write functions
+ png_image_write_to_file()
+ png_image_write_to_stdio()
+
+Starting with libpng-1.6.0, you can configure libpng to prefix all exported
+symbols, using the PNG_PREFIX macro.
+
+We no longer include string.h in png.h. The include statement has been moved
+to pngpriv.h, where it is not accessible by applications. Applications that
+need access to information in string.h must add an '#include <string.h>'
+directive. It does not matter whether this is placed prior to or after
+the '#include "png.h"' directive.
+
+The following API are now DEPRECATED:
+ png_info_init_3()
+ png_convert_to_rfc1123() which has been replaced
+ with png_convert_to_rfc1123_buffer()
+ png_malloc_default()
+ png_free_default()
+ png_reset_zstream()
+
+The following have been removed:
+ png_get_io_chunk_name(), which has been replaced
+ with png_get_io_chunk_type(). The new
+ function returns a 32-bit integer instead of
+ a string.
+ The png_sizeof(), png_strlen(), png_memcpy(), png_memcmp(), and
+ png_memset() macros are no longer used in the libpng sources and
+ have been removed. These had already been made invisible to applications
+ (i.e., defined in the private pngpriv.h header file) since libpng-1.5.0.
+
+The signatures of many exported functions were changed, such that
+ png_structp became png_structrp or png_const_structrp
+ png_infop became png_inforp or png_const_inforp
+where "rp" indicates a "restricted pointer".
+
+Dropped support for 16-bit platforms. The support for FAR/far types has
+been eliminated and the definition of png_alloc_size_t is now controlled
+by a flag so that 'small size_t' systems can select it if necessary.
+
+Error detection in some chunks has improved; in particular the iCCP chunk
+reader now does pretty complete validation of the basic format. Some bad
+profiles that were previously accepted are now accepted with a warning or
+rejected, depending upon the png_set_benign_errors() setting, in particular
+the very old broken Microsoft/HP 3144-byte sRGB profile. Starting with
+libpng-1.6.11, recognizing and checking sRGB profiles can be avoided by
+means of
+
+ #if defined(PNG_SKIP_sRGB_CHECK_PROFILE) && \
+ defined(PNG_SET_OPTION_SUPPORTED)
+ png_set_option(png_ptr, PNG_SKIP_sRGB_CHECK_PROFILE,
+ PNG_OPTION_ON);
+ #endif
+
+It's not a good idea to do this if you are using the "simplified API",
+which needs to be able to recognize sRGB profiles conveyed via the iCCP
+chunk.
+
+The PNG spec requirement that only grayscale profiles may appear in images
+with color type 0 or 4 and that even if the image only contains gray pixels,
+only RGB profiles may appear in images with color type 2, 3, or 6, is now
+enforced. The sRGB chunk is allowed to appear in images with any color type
+and is interpreted by libpng to convey a one-tracer-curve gray profile or a
+three-tracer-curve RGB profile as appropriate.
+
+Prior to libpng-1.6.0 a warning would be issued if the iTXt chunk contained
+an empty language field or an empty translated keyword. Both of these
+are allowed by the PNG specification, so these warnings are no longer issued.
+
+The library now issues an error if the application attempts to set a
+transform after it calls png_read_update_info() or if it attempts to call
+both png_read_update_info() and png_start_read_image() or to call either
+of them more than once.
+
+The default condition for benign_errors is now to treat benign errors as
+warnings while reading and as errors while writing.
+
+The library now issues a warning if both background processing and RGB to
+gray are used when gamma correction happens. As with previous versions of
+the library the results are numerically very incorrect in this case.
+
+There are some minor arithmetic changes in some transforms such as
+png_set_background(), that might be detected by certain regression tests.
+
+Unknown chunk handling has been improved internally, without any API change.
+This adds more correct option control of the unknown handling, corrects
+a pre-existing bug where the per-chunk 'keep' setting is ignored, and makes
+it possible to skip IDAT chunks in the sequential reader.
+
+The machine-generated configure files are no longer included in branches
+libpng16 and later of the GIT repository. They continue to be included
+in the tarball releases, however.
+
+Libpng-1.6.0 through 1.6.2 used the CMF bytes at the beginning of the IDAT
+stream to set the size of the sliding window for reading instead of using the
+default 32-kbyte sliding window size. It was discovered that there are
+hundreds of PNG files in the wild that have incorrect CMF bytes that caused
+zlib to issue the "invalid distance too far back" error and reject the file.
+Libpng-1.6.3 and later calculate their own safe CMF from the image dimensions,
+provide a way to revert to the libpng-1.5.x behavior (ignoring the CMF bytes
+and using a 32-kbyte sliding window), by using
+
+ png_set_option(png_ptr, PNG_MAXIMUM_INFLATE_WINDOW,
+ PNG_OPTION_ON);
+
+and provide a tool (contrib/tools/pngfix) for rewriting a PNG file while
+optimizing the CMF bytes in its IDAT chunk correctly.
+
+Libpng-1.6.0 and libpng-1.6.1 wrote uncompressed iTXt chunks with the wrong
+length, which resulted in PNG files that cannot be read beyond the bad iTXt
+chunk. This error was fixed in libpng-1.6.3, and a tool (called
+contrib/tools/png-fix-itxt) has been added to the libpng distribution.
+
+Starting with libpng-1.6.17, the PNG_SAFE_LIMITS macro was eliminated
+and safe limits are used by default (users who need larger limits
+can still override them at compile time or run time, as described above).
+
+The new limits are
+ default spec limit
+ png_user_width_max 1,000,000 2,147,483,647
+ png_user_height_max 1,000,000 2,147,483,647
+ png_user_chunk_cache_max 128 unlimited
+ png_user_chunk_malloc_max 8,000,000 unlimited
+
+Starting with libpng-1.6.18, a PNG_RELEASE_BUILD macro was added, which allows
+library builders to control compilation for an installed system (a release build).
+It can be set for testing debug or beta builds to ensure that they will compile
+when the build type is switched to RC or STABLE. In essence this overrides the
+PNG_LIBPNG_BUILD_BASE_TYPE definition which is not directly user controllable.
+
+Starting with libpng-1.6.19, attempting to set an over-length PLTE chunk
+is an error. Previously this requirement of the PNG specification was not
+enforced, and the palette was always limited to 256 entries. An over-length
+PLTE chunk found in an input PNG is silently truncated.
+
+XIII. Detecting libpng
+
+The png_get_io_ptr() function has been present since libpng-0.88, has never
+changed, and is unaffected by conditional compilation macros. It is the
+best choice for use in configure scripts for detecting the presence of any
+libpng version since 0.88. In an autoconf "configure.in" you could use
+
+ AC_CHECK_LIB(png, png_get_io_ptr, ...
+
+XV. Source code repository
+
+Since about February 2009, version 1.2.34, libpng has been under "git" source
+control. The git repository was built from old libpng-x.y.z.tar.gz files
+going back to version 0.70. You can access the git repository (read only)
+at
+
+ git://git.code.sf.net/p/libpng/code
+
+or you can browse it with a web browser by selecting the "code" button at
+
+ https://sourceforge.net/projects/libpng
+
+Patches can be sent to glennrp at users.sourceforge.net or to
+png-mng-implement at lists.sourceforge.net or you can upload them to
+the libpng bug tracker at
+
+ http://libpng.sourceforge.net
+
+We also accept patches built from the tar or zip distributions, and
+simple verbal discriptions of bug fixes, reported either to the
+SourceForge bug tracker, to the png-mng-implement at lists.sf.net
+mailing list, or directly to glennrp.
+
+XV. Coding style
+
+Our coding style is similar to the "Allman" style
+(See http://en.wikipedia.org/wiki/Indent_style#Allman_style), with curly
+braces on separate lines:
+
+ if (condition)
+ {
+ action;
+ }
+
+ else if (another condition)
+ {
+ another action;
+ }
+
+The braces can be omitted from simple one-line actions:
+
+ if (condition)
+ return (0);
+
+We use 3-space indentation, except for continued statements which
+are usually indented the same as the first line of the statement
+plus four more spaces.
+
+For macro definitions we use 2-space indentation, always leaving the "#"
+in the first column.
+
+ #ifndef PNG_NO_FEATURE
+ # ifndef PNG_FEATURE_SUPPORTED
+ # define PNG_FEATURE_SUPPORTED
+ # endif
+ #endif
+
+Comments appear with the leading "/*" at the same indentation as
+the statement that follows the comment:
+
+ /* Single-line comment */
+ statement;
+
+ /* This is a multiple-line
+ * comment.
+ */
+ statement;
+
+Very short comments can be placed after the end of the statement
+to which they pertain:
+
+ statement; /* comment */
+
+We don't use C++ style ("//") comments. We have, however,
+used them in the past in some now-abandoned MMX assembler
+code.
+
+Functions and their curly braces are not indented, and
+exported functions are marked with PNGAPI:
+
+ /* This is a public function that is visible to
+ * application programmers. It does thus-and-so.
+ */
+ void PNGAPI
+ png_exported_function(png_ptr, png_info, foo)
+ {
+ body;
+ }
+
+The return type and decorations are placed on a separate line
+ahead of the function name, as illustrated above.
+
+The prototypes for all exported functions appear in png.h,
+above the comment that says
+
+ /* Maintainer: Put new public prototypes here ... */
+
+We mark all non-exported functions with "/* PRIVATE */"":
+
+ void /* PRIVATE */
+ png_non_exported_function(png_ptr, png_info, foo)
+ {
+ body;
+ }
+
+The prototypes for non-exported functions (except for those in
+pngtest) appear in pngpriv.h above the comment that says
+
+ /* Maintainer: Put new private prototypes here ^ */
+
+To avoid polluting the global namespace, the names of all exported
+functions and variables begin with "png_", and all publicly visible C
+preprocessor macros begin with "PNG". We request that applications that
+use libpng *not* begin any of their own symbols with either of these strings.
+
+We put a space after the "sizeof" operator and we omit the
+optional parentheses around its argument when the argument
+is an expression, not a type name, and we always enclose the
+sizeof operator, with its argument, in parentheses:
+
+ (sizeof (png_uint_32))
+ (sizeof array)
+
+Prior to libpng-1.6.0 we used a "png_sizeof()" macro, formatted as
+though it were a function.
+
+Control keywords if, for, while, and switch are always followed by a space
+to distinguish them from function calls, which have no trailing space.
+
+We put a space after each comma and after each semicolon
+in "for" statements, and we put spaces before and after each
+C binary operator and after "for" or "while", and before
+"?". We don't put a space between a typecast and the expression
+being cast, nor do we put one between a function name and the
+left parenthesis that follows it:
+
+ for (i = 2; i > 0; --i)
+ y[i] = a(x) + (int)b;
+
+We prefer #ifdef and #ifndef to #if defined() and #if !defined()
+when there is only one macro being tested. We always use parentheses
+with "defined".
+
+We express integer constants that are used as bit masks in hex format,
+with an even number of lower-case hex digits, and to make them unsigned
+(e.g., 0x00U, 0xffU, 0x0100U) and long if they are greater than 0x7fff
+(e.g., 0xffffUL).
+
+We prefer to use underscores rather than camelCase in names, except
+for a few type names that we inherit from zlib.h.
+
+We prefer "if (something != 0)" and "if (something == 0)"
+over "if (something)" and if "(!something)", respectively.
+
+We do not use the TAB character for indentation in the C sources.
+
+Lines do not exceed 80 characters.
+
+Other rules can be inferred by inspecting the libpng source.
+
+XVI. Y2K Compliance in libpng
+
+Since the PNG Development group is an ad-hoc body, we can't make
+an official declaration.
+
+This is your unofficial assurance that libpng from version 0.71 and
+upward through 1.6.20 are Y2K compliant. It is my belief that earlier
+versions were also Y2K compliant.
+
+Libpng only has two year fields. One is a 2-byte unsigned integer
+that will hold years up to 65535. The other, which is deprecated,
+holds the date in text format, and will hold years up to 9999.
+
+The integer is
+ "png_uint_16 year" in png_time_struct.
+
+The string is
+ "char time_buffer[29]" in png_struct. This is no longer used
+in libpng-1.6.x and will be removed from libpng-1.7.0.
+
+There are seven time-related functions:
+
+ png_convert_to_rfc_1123_buffer() in png.c
+ (formerly png_convert_to_rfc_1152() in error, and
+ also formerly png_convert_to_rfc_1123())
+ png_convert_from_struct_tm() in pngwrite.c, called
+ in pngwrite.c
+ png_convert_from_time_t() in pngwrite.c
+ png_get_tIME() in pngget.c
+ png_handle_tIME() in pngrutil.c, called in pngread.c
+ png_set_tIME() in pngset.c
+ png_write_tIME() in pngwutil.c, called in pngwrite.c
+
+All appear to handle dates properly in a Y2K environment. The
+png_convert_from_time_t() function calls gmtime() to convert from system
+clock time, which returns (year - 1900), which we properly convert to
+the full 4-digit year. There is a possibility that applications using
+libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
+function, or that they are incorrectly passing only a 2-digit year
+instead of "year - 1900" into the png_convert_from_struct_tm() function,
+but this is not under our control. The libpng documentation has always
+stated that it works with 4-digit years, and the APIs have been
+documented as such.
+
+The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned
+integer to hold the year, and can hold years as large as 65535.
+
+zlib, upon which libpng depends, is also Y2K compliant. It contains
+no date-related code.
+
+
+ Glenn Randers-Pehrson
+ libpng maintainer
+ PNG Development Group
diff --git a/libpng/libpng.3 b/libpng/libpng.3
new file mode 100644
index 0000000..357d0ec
--- /dev/null
+++ b/libpng/libpng.3
@@ -0,0 +1,6120 @@
+.TH LIBPNG 3 "December 3, 2015"
+.SH NAME
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.20
+.SH SYNOPSIS
+\fB
+#include <png.h>\fP
+
+\fBpng_uint_32 png_access_version_number \fI(void\fP\fB);\fP
+
+\fBvoid png_benign_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
+
+\fBvoid png_build_grayscale_palette (int \fP\fIbit_depth\fP\fB, png_colorp \fIpalette\fP\fB);\fP
+
+\fBpng_voidp png_calloc (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
+
+\fBvoid png_chunk_benign_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
+
+\fBvoid png_chunk_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
+
+\fBvoid png_chunk_warning (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fImessage\fP\fB);\fP
+
+\fBvoid png_convert_from_struct_tm (png_timep \fP\fIptime\fP\fB, struct tm FAR * \fIttime\fP\fB);\fP
+
+\fBvoid png_convert_from_time_t (png_timep \fP\fIptime\fP\fB, time_t \fIttime\fP\fB);\fP
+
+\fBpng_charp png_convert_to_rfc1123 (png_structp \fP\fIpng_ptr\fP\fB, png_timep \fIptime\fP\fB);\fP
+
+\fBpng_infop png_create_info_struct (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBpng_structp png_create_read_struct (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarn_fn\fP\fB);\fP
+
+\fBpng_structp png_create_read_struct_2 (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fP\fIwarn_fn\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
+
+\fBpng_structp png_create_write_struct (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarn_fn\fP\fB);\fP
+
+\fBpng_structp png_create_write_struct_2 (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fP\fIwarn_fn\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
+
+\fBvoid png_data_freer (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIfreer\fP\fB, png_uint_32 \fImask)\fP\fB);\fP
+
+\fBvoid png_destroy_info_struct (png_structp \fP\fIpng_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP
+
+\fBvoid png_destroy_read_struct (png_structpp \fP\fIpng_ptr_ptr\fP\fB, png_infopp \fP\fIinfo_ptr_ptr\fP\fB, png_infopp \fIend_info_ptr_ptr\fP\fB);\fP
+
+\fBvoid png_destroy_write_struct (png_structpp \fP\fIpng_ptr_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP
+
+\fBvoid png_err (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
+
+\fBvoid png_free (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP
+
+\fBvoid png_free_chunk_list (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_free_default (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP
+
+\fBvoid png_free_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fInum\fP\fB);\fP
+
+\fBpng_byte png_get_bit_depth (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_bKGD (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fI*background\fP\fB);\fP
+
+\fBpng_byte png_get_channels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_cHRM (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, double \fP\fI*white_x\fP\fB, double \fP\fI*white_y\fP\fB, double \fP\fI*red_x\fP\fB, double \fP\fI*red_y\fP\fB, double \fP\fI*green_x\fP\fB, double \fP\fI*green_y\fP\fB, double \fP\fI*blue_x\fP\fB, double \fI*blue_y\fP\fB);\fP
+
+\fBpng_uint_32 png_get_cHRM_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*white_x\fP\fB, png_uint_32 \fP\fI*white_y\fP\fB, png_uint_32 \fP\fI*red_x\fP\fB, png_uint_32 \fP\fI*red_y\fP\fB, png_uint_32 \fP\fI*green_x\fP\fB, png_uint_32 \fP\fI*green_y\fP\fB, png_uint_32 \fP\fI*blue_x\fP\fB, png_uint_32 \fI*blue_y\fP\fB);\fP
+
+\fBpng_uint_32 png_get_cHRM_XYZ (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, double \fP\fI*red_X\fP\fB, double \fP\fI*red_Y\fP\fB, double \fP\fI*red_Z\fP\fB, double \fP\fI*green_X\fP\fB, double \fP\fI*green_Y\fP\fB, double \fP\fI*green_Z\fP\fB, double \fP\fI*blue_X\fP\fB, double \fP\fI*blue_Y\fP\fB, double \fI*blue_Z\fP\fB);\fP
+
+\fBpng_uint_32 png_get_cHRM_XYZ_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_fixed_point \fP\fI*int_red_X\fP\fB, png_fixed_point \fP\fI*int_red_Y\fP\fB, png_fixed_point \fP\fI*int_red_Z\fP\fB, png_fixed_point \fP\fI*int_green_X\fP\fB, png_fixed_point \fP\fI*int_green_Y\fP\fB, png_fixed_point \fP\fI*int_green_Z\fP\fB, png_fixed_point \fP\fI*int_blue_X\fP\fB, png_fixed_point \fP\fI*int_blue_Y\fP\fB, png_fixed_point \fI*int_blue_Z\fP\fB);\fP
+
+\fBpng_uint_32 png_get_chunk_cache_max (png_const_structp \fIpng_ptr\fP\fB);\fP
+
+\fBpng_alloc_size_t png_get_chunk_malloc_max (png_const_structp \fIpng_ptr\fP\fB);\fP
+
+\fBpng_byte png_get_color_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_compression_buffer_size (png_const_structp \fIpng_ptr\fP\fB);\fP
+
+\fBpng_byte png_get_compression_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_byte png_get_copyright (png_const_structp \fIpng_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_current_row_number \fI(png_const_structp\fP\fB);\fP
+
+\fBpng_byte png_get_current_pass_number \fI(png_const_structp\fP\fB);\fP
+
+\fBpng_voidp png_get_error_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
+
+\fBpng_byte png_get_filter_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_gAMA (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, double \fI*file_gamma\fP\fB);\fP
+
+\fBpng_uint_32 png_get_gAMA_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fI*int_file_gamma\fP\fB);\fP
+
+\fBpng_byte png_get_header_ver (png_const_structp \fIpng_ptr\fP\fB);\fP
+
+\fBpng_byte png_get_header_version (png_const_structp \fIpng_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_hIST (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fI*hist\fP\fB);\fP
+
+\fBpng_uint_32 png_get_iCCP (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_charpp \fP\fIname\fP\fB, int \fP\fI*compression_type\fP\fB, png_bytepp \fP\fIprofile\fP\fB, png_uint_32 \fI*proflen\fP\fB);\fP
+
+\fBpng_uint_32 png_get_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*width\fP\fB, png_uint_32 \fP\fI*height\fP\fB, int \fP\fI*bit_depth\fP\fB, int \fP\fI*color_type\fP\fB, int \fP\fI*interlace_type\fP\fB, int \fP\fI*compression_type\fP\fB, int \fI*filter_type\fP\fB);\fP
+
+\fBpng_uint_32 png_get_image_height (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_image_width (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_int_32 png_get_int_32 (png_bytep \fIbuf\fP\fB);\fP
+
+\fBpng_byte png_get_interlace_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_io_chunk_type (png_const_structp \fIpng_ptr\fP\fB);\fP
+
+\fBpng_voidp png_get_io_ptr (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_io_state (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBpng_byte png_get_libpng_ver (png_const_structp \fIpng_ptr\fP\fB);\fP
+
+\fBint png_get_palette_max(png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_voidp png_get_mem_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_oFFs (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*offset_x\fP\fB, png_uint_32 \fP\fI*offset_y\fP\fB, int \fI*unit_type\fP\fB);\fP
+
+\fBpng_uint_32 png_get_pCAL (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fI*purpose\fP\fB, png_int_32 \fP\fI*X0\fP\fB, png_int_32 \fP\fI*X1\fP\fB, int \fP\fI*type\fP\fB, int \fP\fI*nparams\fP\fB, png_charp \fP\fI*units\fP\fB, png_charpp \fI*params\fP\fB);\fP
+
+\fBpng_uint_32 png_get_pHYs (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*res_x\fP\fB, png_uint_32 \fP\fI*res_y\fP\fB, int \fI*unit_type\fP\fB);\fP
+
+\fBfloat png_get_pixel_aspect_ratio (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_pHYs_dpi (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*res_x\fP\fB, png_uint_32 \fP\fI*res_y\fP\fB, int \fI*unit_type\fP\fB);\fP
+
+\fBpng_fixed_point png_get_pixel_aspect_ratio_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_voidp png_get_progressive_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_PLTE (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_colorp \fP\fI*palette\fP\fB, int \fI*num_palette\fP\fB);\fP
+
+\fBpng_byte png_get_rgb_to_gray_status (png_const_structp \fIpng_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_rowbytes (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_bytepp png_get_rows (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_sBIT (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_8p \fI*sig_bit\fP\fB);\fP
+
+\fBvoid png_get_sCAL (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, double* \fP\fIwidth\fP\fB, double* \fIheight\fP\fB);\fP
+
+\fBvoid png_get_sCAL_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, png_fixed_pointp \fP\fIwidth\fP\fB, png_fixed_pointp \fIheight\fP\fB);\fP
+
+\fBvoid png_get_sCAL_s (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, png_charpp \fP\fIwidth\fP\fB, png_charpp \fIheight\fP\fB);\fP
+
+\fBpng_bytep png_get_signature (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_sPLT (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_spalette_p \fI*splt_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_sRGB (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int \fI*file_srgb_intent\fP\fB);\fP
+
+\fBpng_uint_32 png_get_text (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fI*text_ptr\fP\fB, int \fI*num_text\fP\fB);\fP
+
+\fBpng_uint_32 png_get_tIME (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fI*mod_time\fP\fB);\fP
+
+\fBpng_uint_32 png_get_tRNS (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fI*trans_alpha\fP\fB, int \fP\fI*num_trans\fP\fB, png_color_16p \fI*trans_color\fP\fB);\fP
+
+\fB/* This function is really an inline macro. \fI*/
+
+\fBpng_uint_16 png_get_uint_16 (png_bytep \fIbuf\fP\fB);\fP
+
+\fBpng_uint_32 png_get_uint_31 (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIbuf\fP\fB);\fP
+
+\fB/* This function is really an inline macro. \fI*/
+
+\fBpng_uint_32 png_get_uint_32 (png_bytep \fIbuf\fP\fB);\fP
+
+\fBpng_uint_32 png_get_unknown_chunks (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_unknown_chunkpp \fIunknowns\fP\fB);\fP
+
+\fBpng_voidp png_get_user_chunk_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_user_height_max (png_const_structp \fIpng_ptr\fP\fB);\fP
+
+\fBpng_voidp png_get_user_transform_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_user_width_max (png_const_structp \fIpng_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_valid (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIflag\fP\fB);\fP
+
+\fBfloat png_get_x_offset_inches (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_fixed_point png_get_x_offset_inches_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_int_32 png_get_x_offset_microns (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_int_32 png_get_x_offset_pixels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_x_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_x_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBfloat png_get_y_offset_inches (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_fixed_point png_get_y_offset_inches_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_int_32 png_get_y_offset_microns (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_int_32 png_get_y_offset_pixels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_y_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_get_y_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBint png_handle_as_unknown (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIchunk_name\fP\fB);\fP
+
+\fBint png_image_begin_read_from_file (png_imagep \fP\fIimage\fP\fB, const char \fI*file_name\fP\fB);\fP
+
+\fBint png_image_begin_read_from_stdio (png_imagep \fP\fIimage\fP\fB, FILE* \fIfile\fP\fB);\fP
+
+\fBint, png_image_begin_read_from_memory (png_imagep \fP\fIimage\fP\fB, png_const_voidp \fP\fImemory\fP\fB, png_size_t \fIsize\fP\fB);\fP
+
+\fBint png_image_finish_read (png_imagep \fP\fIimage\fP\fB, png_colorp \fP\fIbackground\fP\fB, void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap\fP\fB);\fP
+
+\fBvoid png_image_free (png_imagep \fIimage\fP\fB);\fP
+
+\fBint png_image_write_to_file (png_imagep \fP\fIimage\fP\fB, const char \fP\fI*file\fP\fB, int \fP\fIconvert_to_8bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap\fP\fB);\fP
+
+\fBint png_image_write_to_stdio (png_imagep \fP\fIimage\fP\fB, FILE \fP\fI*file\fP\fB, int \fP\fIconvert_to_8_bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap)\fP\fB);\fP
+
+\fBvoid png_info_init_3 (png_infopp \fP\fIinfo_ptr\fP\fB, png_size_t \fIpng_info_struct_size\fP\fB);\fP
+
+\fBvoid png_init_io (png_structp \fP\fIpng_ptr\fP\fB, FILE \fI*fp\fP\fB);\fP
+
+\fBvoid png_longjmp (png_structp \fP\fIpng_ptr\fP\fB, int \fIval\fP\fB);\fP
+
+\fBpng_voidp png_malloc (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
+
+\fBpng_voidp png_malloc_default (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
+
+\fBpng_voidp png_malloc_warn (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
+
+\fBpng_uint_32 png_permit_mng_features (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fImng_features_permitted\fP\fB);\fP
+
+\fBvoid png_process_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fIbuffer\fP\fB, png_size_t \fIbuffer_size\fP\fB);\fP
+
+\fBpng_size_t png_process_data_pause \fP\fI(png_structp\fP\fB, int \fIsave\fP\fB);\fP
+
+\fBpng_uint_32 png_process_data_skip \fI(png_structp\fP\fB);\fP
+
+\fBvoid png_progressive_combine_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIold_row\fP\fB, png_bytep \fInew_row\fP\fB);\fP
+
+\fBvoid png_read_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBvoid png_read_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP
+
+\fBvoid png_read_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBvoid png_read_png (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fItransforms\fP\fB, png_voidp \fIparams\fP\fB);\fP
+
+\fBvoid png_read_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIrow\fP\fB, png_bytep \fIdisplay_row\fP\fB);\fP
+
+\fBvoid png_read_rows (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fP\fIrow\fP\fB, png_bytepp \fP\fIdisplay_row\fP\fB, png_uint_32 \fInum_rows\fP\fB);\fP
+
+\fBvoid png_read_update_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBint png_reset_zstream (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_save_int_32 (png_bytep \fP\fIbuf\fP\fB, png_int_32 \fIi\fP\fB);\fP
+
+\fBvoid png_save_uint_16 (png_bytep \fP\fIbuf\fP\fB, unsigned int \fIi\fP\fB);\fP
+
+\fBvoid png_save_uint_32 (png_bytep \fP\fIbuf\fP\fB, png_uint_32 \fIi\fP\fB);\fP
+
+\fBvoid png_set_add_alpha (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, int \fIflags\fP\fB);\fP
+
+\fBvoid png_set_alpha_mode (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImode\fP\fB, double \fIoutput_gamma\fP\fB);\fP
+
+\fBvoid png_set_alpha_mode_fixed (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImode\fP\fB, png_fixed_point \fIoutput_gamma\fP\fB);\fP
+
+\fBvoid png_set_background (png_structp \fP\fIpng_ptr\fP\fB, png_color_16p \fP\fIbackground_color\fP\fB, int \fP\fIbackground_gamma_code\fP\fB, int \fP\fIneed_expand\fP\fB, double \fIbackground_gamma\fP\fB);\fP
+
+\fBvoid png_set_background_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_color_16p \fP\fIbackground_color\fP\fB, int \fP\fIbackground_gamma_code\fP\fB, int \fP\fIneed_expand\fP\fB, png_uint_32 \fIbackground_gamma\fP\fB);\fP
+
+\fBvoid png_set_benign_errors (png_structp \fP\fIpng_ptr\fP\fB, int \fIallowed\fP\fB);\fP
+
+\fBvoid png_set_bgr (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_set_bKGD (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fIbackground\fP\fB);\fP
+
+\fBvoid png_set_check_for_invalid_index(png_structrp \fP\fIpng_ptr\fP\fB, int \fIallowed\fP\fB);\fP
+
+\fBvoid png_set_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fP\fIwhite_x\fP\fB, double \fP\fIwhite_y\fP\fB, double \fP\fIred_x\fP\fB, double \fP\fIred_y\fP\fB, double \fP\fIgreen_x\fP\fB, double \fP\fIgreen_y\fP\fB, double \fP\fIblue_x\fP\fB, double \fIblue_y\fP\fB);\fP
+
+\fBvoid png_set_cHRM_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIwhite_x\fP\fB, png_uint_32 \fP\fIwhite_y\fP\fB, png_uint_32 \fP\fIred_x\fP\fB, png_uint_32 \fP\fIred_y\fP\fB, png_uint_32 \fP\fIgreen_x\fP\fB, png_uint_32 \fP\fIgreen_y\fP\fB, png_uint_32 \fP\fIblue_x\fP\fB, png_uint_32 \fIblue_y\fP\fB);\fP
+
+\fBvoid png_set_cHRM_XYZ (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fP\fIred_X\fP\fB, double \fP\fIred_Y\fP\fB, double \fP\fIred_Z\fP\fB, double \fP\fIgreen_X\fP\fB, double \fP\fIgreen_Y\fP\fB, double \fP\fIgreen_Z\fP\fB, double \fP\fIblue_X\fP\fB, double \fP\fIblue_Y\fP\fB, double \fIblue_Z\fP\fB);\fP
+
+\fBvoid png_set_cHRM_XYZ_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_fixed_point \fP\fIint_red_X\fP\fB, png_fixed_point \fP\fIint_red_Y\fP\fB, png_fixed_point \fP\fIint_red_Z\fP\fB, png_fixed_point \fP\fIint_green_X\fP\fB, png_fixed_point \fP\fIint_green_Y\fP\fB, png_fixed_point \fP\fIint_green_Z\fP\fB, png_fixed_point \fP\fIint_blue_X\fP\fB, png_fixed_point \fP\fIint_blue_Y\fP\fB, png_fixed_point \fIint_blue_Z\fP\fB);\fP
+
+\fBvoid png_set_chunk_cache_max (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIuser_chunk_cache_max\fP\fB);\fP
+
+\fBvoid png_set_compression_level (png_structp \fP\fIpng_ptr\fP\fB, int \fIlevel\fP\fB);\fP
+
+\fBvoid png_set_compression_mem_level (png_structp \fP\fIpng_ptr\fP\fB, int \fImem_level\fP\fB);\fP
+
+\fBvoid png_set_compression_method (png_structp \fP\fIpng_ptr\fP\fB, int \fImethod\fP\fB);\fP
+
+\fBvoid png_set_compression_strategy (png_structp \fP\fIpng_ptr\fP\fB, int \fIstrategy\fP\fB);\fP
+
+\fBvoid png_set_compression_window_bits (png_structp \fP\fIpng_ptr\fP\fB, int \fIwindow_bits\fP\fB);\fP
+
+\fBvoid png_set_crc_action (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIcrit_action\fP\fB, int \fIancil_action\fP\fB);\fP
+
+\fBvoid png_set_error_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarning_fn\fP\fB);\fP
+
+\fBvoid png_set_expand (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_set_expand_16 (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_set_expand_gray_1_2_4_to_8 (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_set_filler (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, int \fIflags\fP\fB);\fP
+
+\fBvoid png_set_filter (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImethod\fP\fB, int \fIfilters\fP\fB);\fP
+
+\fBvoid png_set_filter_heuristics (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIheuristic_method\fP\fB, int \fP\fInum_weights\fP\fB, png_doublep \fP\fIfilter_weights\fP\fB, png_doublep \fIfilter_costs\fP\fB);\fP
+
+\fBvoid png_set_filter_heuristics_fixed (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIheuristic_method\fP\fB, int \fP\fInum_weights\fP\fB, png_fixed_point_p \fP\fIfilter_weights\fP\fB, png_fixed_point_p \fIfilter_costs\fP\fB);\fP
+
+\fBvoid png_set_flush (png_structp \fP\fIpng_ptr\fP\fB, int \fInrows\fP\fB);\fP
+
+\fBvoid png_set_gamma (png_structp \fP\fIpng_ptr\fP\fB, double \fP\fIscreen_gamma\fP\fB, double \fIdefault_file_gamma\fP\fB);\fP
+
+\fBvoid png_set_gamma_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIscreen_gamma\fP\fB, png_uint_32 \fIdefault_file_gamma\fP\fB);\fP
+
+\fBvoid png_set_gAMA (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fIfile_gamma\fP\fB);\fP
+
+\fBvoid png_set_gAMA_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIfile_gamma\fP\fB);\fP
+
+\fBvoid png_set_gray_1_2_4_to_8 (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_set_gray_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_set_hIST (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fIhist\fP\fB);\fP
+
+\fBvoid png_set_iCCP (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_const_charp \fP\fIname\fP\fB, int \fP\fIcompression_type\fP\fB, png_const_bytep \fP\fIprofile\fP\fB, png_uint_32 \fIproflen\fP\fB);\fP
+
+\fBint png_set_interlace_handling (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_set_invalid (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fImask\fP\fB);\fP
+
+\fBvoid png_set_invert_alpha (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_set_invert_mono (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_set_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIwidth\fP\fB, png_uint_32 \fP\fIheight\fP\fB, int \fP\fIbit_depth\fP\fB, int \fP\fIcolor_type\fP\fB, int \fP\fIinterlace_type\fP\fB, int \fP\fIcompression_type\fP\fB, int \fIfilter_type\fP\fB);\fP
+
+\fBvoid png_set_keep_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIkeep\fP\fB, png_bytep \fP\fIchunk_list\fP\fB, int \fInum_chunks\fP\fB);\fP
+
+\fBjmp_buf* png_set_longjmp_fn (png_structp \fP\fIpng_ptr\fP\fB, png_longjmp_ptr \fP\fIlongjmp_fn\fP\fB, size_t \fIjmp_buf_size\fP\fB);\fP
+
+\fBvoid png_set_chunk_malloc_max (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIuser_chunk_cache_max\fP\fB);\fP
+
+\fBvoid png_set_compression_buffer_size (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIsize\fP\fB);\fP
+
+\fBvoid png_set_mem_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
+
+\fBvoid png_set_oFFs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIoffset_x\fP\fB, png_uint_32 \fP\fIoffset_y\fP\fB, int \fIunit_type\fP\fB);\fP
+
+\fBint png_set_option(png_structrp \fP\fIpng_ptr\fP\fB, int \fP\fIoption\fP\fB, int \fIonoff\fP\fB);\fP
+
+\fBvoid png_set_packing (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_set_packswap (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_set_palette_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_set_pCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fIpurpose\fP\fB, png_int_32 \fP\fIX0\fP\fB, png_int_32 \fP\fIX1\fP\fB, int \fP\fItype\fP\fB, int \fP\fInparams\fP\fB, png_charp \fP\fIunits\fP\fB, png_charpp \fIparams\fP\fB);\fP
+
+\fBvoid png_set_pHYs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIres_x\fP\fB, png_uint_32 \fP\fIres_y\fP\fB, int \fIunit_type\fP\fB);\fP
+
+\fBvoid png_set_progressive_read_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIprogressive_ptr\fP\fB, png_progressive_info_ptr \fP\fIinfo_fn\fP\fB, png_progressive_row_ptr \fP\fIrow_fn\fP\fB, png_progressive_end_ptr \fIend_fn\fP\fB);\fP
+
+\fBvoid png_set_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fInum_palette\fP\fB);\fP
+
+\fBvoid png_set_quantize (png_structp \fP\fIpng_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fP\fInum_palette\fP\fB, int \fP\fImaximum_colors\fP\fB, png_uint_16p \fP\fIhistogram\fP\fB, int \fIfull_quantize\fP\fB);\fP
+
+\fBvoid png_set_read_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIio_ptr\fP\fB, png_rw_ptr \fIread_data_fn\fP\fB);\fP
+
+\fBvoid png_set_read_status_fn (png_structp \fP\fIpng_ptr\fP\fB, png_read_status_ptr \fIread_row_fn\fP\fB);\fP
+
+\fBvoid png_set_read_user_chunk_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIuser_chunk_ptr\fP\fB, png_user_chunk_ptr \fIread_user_chunk_fn\fP\fB);\fP
+
+\fBvoid png_set_read_user_transform_fn (png_structp \fP\fIpng_ptr\fP\fB, png_user_transform_ptr \fIread_user_transform_fn\fP\fB);\fP
+
+\fBvoid png_set_rgb_to_gray (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIerror_action\fP\fB, double \fP\fIred\fP\fB, double \fIgreen\fP\fB);\fP
+
+\fBvoid png_set_rgb_to_gray_fixed (png_structp \fP\fIpng_ptr\fP\fB, int error_action png_uint_32 \fP\fIred\fP\fB, png_uint_32 \fIgreen\fP\fB);\fP
+
+\fBvoid png_set_rows (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytepp \fIrow_pointers\fP\fB);\fP
+
+\fBvoid png_set_sBIT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_8p \fIsig_bit\fP\fB);\fP
+
+\fBvoid png_set_sCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, double \fP\fIwidth\fP\fB, double \fIheight\fP\fB);\fP
+
+\fBvoid png_set_sCAL_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, png_fixed_point \fP\fIwidth\fP\fB, png_fixed_point \fIheight\fP\fB);\fP
+
+\fBvoid png_set_sCAL_s (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, png_charp \fP\fIwidth\fP\fB, png_charp \fIheight\fP\fB);\fP
+
+\fBvoid png_set_scale_16 (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_set_shift (png_structp \fP\fIpng_ptr\fP\fB, png_color_8p \fItrue_bits\fP\fB);\fP
+
+\fBvoid png_set_sig_bytes (png_structp \fP\fIpng_ptr\fP\fB, int \fInum_bytes\fP\fB);\fP
+
+\fBvoid png_set_sPLT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_spalette_p \fP\fIsplt_ptr\fP\fB, int \fInum_spalettes\fP\fB);\fP
+
+\fBvoid png_set_sRGB (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIsrgb_intent\fP\fB);\fP
+
+\fBvoid png_set_sRGB_gAMA_and_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIsrgb_intent\fP\fB);\fP
+
+\fBvoid png_set_strip_16 (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_set_strip_alpha (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_set_strip_error_numbers (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIstrip_mode\fP\fB);\fP
+
+\fBvoid png_set_swap (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_set_swap_alpha (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_set_text (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fItext_ptr\fP\fB, int \fInum_text\fP\fB);\fP
+
+\fBvoid png_set_text_compression_level (png_structp \fP\fIpng_ptr\fP\fB, int \fIlevel\fP\fB);\fP
+
+\fBvoid png_set_text_compression_mem_level (png_structp \fP\fIpng_ptr\fP\fB, int \fImem_level\fP\fB);\fP
+
+\fBvoid png_set_text_compression_strategy (png_structp \fP\fIpng_ptr\fP\fB, int \fIstrategy\fP\fB);\fP
+
+\fBvoid png_set_text_compression_window_bits (png_structp \fP\fIpng_ptr\fP\fB, int \fIwindow_bits\fP\fB);\fP
+
+\fBvoid \fP\fIpng_set_text_compression_method\fP\fB, (png_structp \fP\fIpng_ptr\fP\fB, int \fImethod)\fP\fB);\fP
+
+\fBvoid png_set_tIME (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fImod_time\fP\fB);\fP
+
+\fBvoid png_set_tRNS (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fItrans_alpha\fP\fB, int \fP\fInum_trans\fP\fB, png_color_16p \fItrans_color\fP\fB);\fP
+
+\fBvoid png_set_tRNS_to_alpha (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBpng_uint_32 png_set_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_unknown_chunkp \fP\fIunknowns\fP\fB, int \fP\fInum\fP\fB, int \fIlocation\fP\fB);\fP
+
+\fBvoid png_set_unknown_chunk_location (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIchunk\fP\fB, int \fIlocation\fP\fB);\fP
+
+\fBvoid png_set_user_limits (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIuser_width_max\fP\fB, png_uint_32 \fIuser_height_max\fP\fB);\fP
+
+\fBvoid png_set_user_transform_info (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIuser_transform_ptr\fP\fB, int \fP\fIuser_transform_depth\fP\fB, int \fIuser_transform_channels\fP\fB);\fP
+
+\fBvoid png_set_write_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIio_ptr\fP\fB, png_rw_ptr \fP\fIwrite_data_fn\fP\fB, png_flush_ptr \fIoutput_flush_fn\fP\fB);\fP
+
+\fBvoid png_set_write_status_fn (png_structp \fP\fIpng_ptr\fP\fB, png_write_status_ptr \fIwrite_row_fn\fP\fB);\fP
+
+\fBvoid png_set_write_user_transform_fn (png_structp \fP\fIpng_ptr\fP\fB, png_user_transform_ptr \fIwrite_user_transform_fn\fP\fB);\fP
+
+\fBint png_sig_cmp (png_bytep \fP\fIsig\fP\fB, png_size_t \fP\fIstart\fP\fB, png_size_t \fInum_to_check\fP\fB);\fP
+
+\fBvoid png_start_read_image (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_warning (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fImessage\fP\fB);\fP
+
+\fBvoid png_write_chunk (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP
+
+\fBvoid png_write_chunk_data (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP
+
+\fBvoid png_write_chunk_end (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_write_chunk_start (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
+
+\fBvoid png_write_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBvoid png_write_flush (png_structp \fIpng_ptr\fP\fB);\fP
+
+\fBvoid png_write_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP
+
+\fBvoid png_write_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBvoid png_write_info_before_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
+
+\fBvoid png_write_png (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fItransforms\fP\fB, png_voidp \fIparams\fP\fB);\fP
+
+\fBvoid png_write_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIrow\fP\fB);\fP
+
+\fBvoid png_write_rows (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fP\fIrow\fP\fB, png_uint_32 \fInum_rows\fP\fB);\fP
+
+\fBvoid png_write_sig (png_structp \fIpng_ptr\fP\fB);\fP
+
+.SH DESCRIPTION
+The
+.I libpng
+library supports encoding, decoding, and various manipulations of
+the Portable Network Graphics (PNG) format image files. It uses the
+.IR zlib(3)
+compression library.
+Following is a copy of the libpng-manual.txt file that accompanies libpng.
+.SH LIBPNG.TXT
+libpng-manual.txt - A description on how to use and modify libpng
+
+ libpng version 1.6.20 - December 3, 2015
+ Updated and distributed by Glenn Randers-Pehrson
+ <glennrp at users.sourceforge.net>
+ Copyright (c) 1998-2015 Glenn Randers-Pehrson
+
+ This document is released under the libpng license.
+ For conditions of distribution and use, see the disclaimer
+ and license in png.h
+
+ Based on:
+
+ libpng versions 0.97, January 1998, through 1.6.20 - December 3, 2015
+ Updated and distributed by Glenn Randers-Pehrson
+ Copyright (c) 1998-2015 Glenn Randers-Pehrson
+
+ libpng 1.0 beta 6 - version 0.96 - May 28, 1997
+ Updated and distributed by Andreas Dilger
+ Copyright (c) 1996, 1997 Andreas Dilger
+
+ libpng 1.0 beta 2 - version 0.88 - January 26, 1996
+ For conditions of distribution and use, see copyright
+ notice in png.h. Copyright (c) 1995, 1996 Guy Eric
+ Schalnat, Group 42, Inc.
+
+ Updated/rewritten per request in the libpng FAQ
+ Copyright (c) 1995, 1996 Frank J. T. Wojcik
+ December 18, 1995 & January 20, 1996
+
+ TABLE OF CONTENTS
+
+ I. Introduction
+ II. Structures
+ III. Reading
+ IV. Writing
+ V. Simplified API
+ VI. Modifying/Customizing libpng
+ VII. MNG support
+ VIII. Changes to Libpng from version 0.88
+ IX. Changes to Libpng from version 1.0.x to 1.2.x
+ X. Changes to Libpng from version 1.0.x/1.2.x to 1.4.x
+ XI. Changes to Libpng from version 1.4.x to 1.5.x
+ XII. Changes to Libpng from version 1.5.x to 1.6.x
+ XIII. Detecting libpng
+ XIV. Source code repository
+ XV. Coding style
+ XVI. Y2K Compliance in libpng
+
+.SH I. Introduction
+
+This file describes how to use and modify the PNG reference library
+(known as libpng) for your own use. In addition to this
+file, example.c is a good starting point for using the library, as
+it is heavily commented and should include everything most people
+will need. We assume that libpng is already installed; see the
+INSTALL file for instructions on how to configure and install libpng.
+
+For examples of libpng usage, see the files "example.c", "pngtest.c",
+and the files in the "contrib" directory, all of which are included in
+the libpng distribution.
+
+Libpng was written as a companion to the PNG specification, as a way
+of reducing the amount of time and effort it takes to support the PNG
+file format in application programs.
+
+The PNG specification (second edition), November 2003, is available as
+a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2004 (E)) at
+<http://www.w3.org/TR/2003/REC-PNG-20031110/
+The W3C and ISO documents have identical technical content.
+
+The PNG-1.2 specification is available at
+<http://png-mng.sourceforge.net/pub/png/spec/1.2/>.
+It is technically equivalent
+to the PNG specification (second edition) but has some additional material.
+
+The PNG-1.0 specification is available as RFC 2083
+<http://png-mng.sourceforge.net/pub/png/spec/1.0/> and as a
+W3C Recommendation <http://www.w3.org/TR/REC-png-961001>.
+
+Some additional chunks are described in the special-purpose public chunks
+documents at <http://www.libpng.org/pub/png/spec/register/>
+
+Other information
+about PNG, and the latest version of libpng, can be found at the PNG home
+page, <http://www.libpng.org/pub/png/>.
+
+Most users will not have to modify the library significantly; advanced
+users may want to modify it more. All attempts were made to make it as
+complete as possible, while keeping the code easy to understand.
+Currently, this library only supports C. Support for other languages
+is being considered.
+
+Libpng has been designed to handle multiple sessions at one time,
+to be easily modifiable, to be portable to the vast majority of
+machines (ANSI, K&R, 16-, 32-, and 64-bit) available, and to be easy
+to use. The ultimate goal of libpng is to promote the acceptance of
+the PNG file format in whatever way possible. While there is still
+work to be done (see the TODO file), libpng should cover the
+majority of the needs of its users.
+
+Libpng uses zlib for its compression and decompression of PNG files.
+Further information about zlib, and the latest version of zlib, can
+be found at the zlib home page, <http://zlib.net/>.
+The zlib compression utility is a general purpose utility that is
+useful for more than PNG files, and can be used without libpng.
+See the documentation delivered with zlib for more details.
+You can usually find the source files for the zlib utility wherever you
+find the libpng source files.
+
+Libpng is thread safe, provided the threads are using different
+instances of the structures. Each thread should have its own
+png_struct and png_info instances, and thus its own image.
+Libpng does not protect itself against two threads using the
+same instance of a structure.
+
+.SH II. Structures
+
+There are two main structures that are important to libpng, png_struct
+and png_info. Both are internal structures that are no longer exposed
+in the libpng interface (as of libpng 1.5.0).
+
+The png_info structure is designed to provide information about the
+PNG file. At one time, the fields of png_info were intended to be
+directly accessible to the user. However, this tended to cause problems
+with applications using dynamically loaded libraries, and as a result
+a set of interface functions for png_info (the png_get_*() and png_set_*()
+functions) was developed, and direct access to the png_info fields was
+deprecated..
+
+The png_struct structure is the object used by the library to decode a
+single image. As of 1.5.0 this structure is also not exposed.
+
+Almost all libpng APIs require a pointer to a png_struct as the first argument.
+Many (in particular the png_set and png_get APIs) also require a pointer
+to png_info as the second argument. Some application visible macros
+defined in png.h designed for basic data access (reading and writing
+integers in the PNG format) don't take a png_info pointer, but it's almost
+always safe to assume that a (png_struct*) has to be passed to call an API
+function.
+
+You can have more than one png_info structure associated with an image,
+as illustrated in pngtest.c, one for information valid prior to the
+IDAT chunks and another (called "end_info" below) for things after them.
+
+The png.h header file is an invaluable reference for programming with libpng.
+And while I'm on the topic, make sure you include the libpng header file:
+
+#include <png.h>
+
+and also (as of libpng-1.5.0) the zlib header file, if you need it:
+
+#include <zlib.h>
+
+.SS Types
+
+The png.h header file defines a number of integral types used by the
+APIs. Most of these are fairly obvious; for example types corresponding
+to integers of particular sizes and types for passing color values.
+
+One exception is how non-integral numbers are handled. For application
+convenience most APIs that take such numbers have C (double) arguments;
+however, internally PNG, and libpng, use 32 bit signed integers and encode
+the value by multiplying by 100,000. As of libpng 1.5.0 a convenience
+macro PNG_FP_1 is defined in png.h along with a type (png_fixed_point)
+which is simply (png_int_32).
+
+All APIs that take (double) arguments also have a matching API that
+takes the corresponding fixed point integer arguments. The fixed point
+API has the same name as the floating point one with "_fixed" appended.
+The actual range of values permitted in the APIs is frequently less than
+the full range of (png_fixed_point) (\-21474 to +21474). When APIs require
+a non-negative argument the type is recorded as png_uint_32 above. Consult
+the header file and the text below for more information.
+
+Special care must be take with sCAL chunk handling because the chunk itself
+uses non-integral values encoded as strings containing decimal floating point
+numbers. See the comments in the header file.
+
+.SS Configuration
+
+The main header file function declarations are frequently protected by C
+preprocessing directives of the form:
+
+ #ifdef PNG_feature_SUPPORTED
+ declare-function
+ #endif
+ ...
+ #ifdef PNG_feature_SUPPORTED
+ use-function
+ #endif
+
+The library can be built without support for these APIs, although a
+standard build will have all implemented APIs. Application programs
+should check the feature macros before using an API for maximum
+portability. From libpng 1.5.0 the feature macros set during the build
+of libpng are recorded in the header file "pnglibconf.h" and this file
+is always included by png.h.
+
+If you don't need to change the library configuration from the default, skip to
+the next section ("Reading").
+
+Notice that some of the makefiles in the 'scripts' directory and (in 1.5.0) all
+of the build project files in the 'projects' directory simply copy
+scripts/pnglibconf.h.prebuilt to pnglibconf.h. This means that these build
+systems do not permit easy auto-configuration of the library - they only
+support the default configuration.
+
+The easiest way to make minor changes to the libpng configuration when
+auto-configuration is supported is to add definitions to the command line
+using (typically) CPPFLAGS. For example:
+
+CPPFLAGS=\-DPNG_NO_FLOATING_ARITHMETIC
+
+will change the internal libpng math implementation for gamma correction and
+other arithmetic calculations to fixed point, avoiding the need for fast
+floating point support. The result can be seen in the generated pnglibconf.h -
+make sure it contains the changed feature macro setting.
+
+If you need to make more extensive configuration changes - more than one or two
+feature macro settings - you can either add \-DPNG_USER_CONFIG to the build
+command line and put a list of feature macro settings in pngusr.h or you can set
+DFA_XTRA (a makefile variable) to a file containing the same information in the
+form of 'option' settings.
+
+A. Changing pnglibconf.h
+
+A variety of methods exist to build libpng. Not all of these support
+reconfiguration of pnglibconf.h. To reconfigure pnglibconf.h it must either be
+rebuilt from scripts/pnglibconf.dfa using awk or it must be edited by hand.
+
+Hand editing is achieved by copying scripts/pnglibconf.h.prebuilt to
+pnglibconf.h and changing the lines defining the supported features, paying
+very close attention to the 'option' information in scripts/pnglibconf.dfa
+that describes those features and their requirements. This is easy to get
+wrong.
+
+B. Configuration using DFA_XTRA
+
+Rebuilding from pnglibconf.dfa is easy if a functioning 'awk', or a later
+variant such as 'nawk' or 'gawk', is available. The configure build will
+automatically find an appropriate awk and build pnglibconf.h.
+The scripts/pnglibconf.mak file contains a set of make rules for doing the
+same thing if configure is not used, and many of the makefiles in the scripts
+directory use this approach.
+
+When rebuilding simply write a new file containing changed options and set
+DFA_XTRA to the name of this file. This causes the build to append the new file
+to the end of scripts/pnglibconf.dfa. The pngusr.dfa file should contain lines
+of the following forms:
+
+everything = off
+
+This turns all optional features off. Include it at the start of pngusr.dfa to
+make it easier to build a minimal configuration. You will need to turn at least
+some features on afterward to enable either reading or writing code, or both.
+
+option feature on
+option feature off
+
+Enable or disable a single feature. This will automatically enable other
+features required by a feature that is turned on or disable other features that
+require a feature which is turned off. Conflicting settings will cause an error
+message to be emitted by awk.
+
+setting feature default value
+
+Changes the default value of setting 'feature' to 'value'. There are a small
+number of settings listed at the top of pnglibconf.h, they are documented in the
+source code. Most of these values have performance implications for the library
+but most of them have no visible effect on the API. Some can also be overridden
+from the API.
+
+This method of building a customized pnglibconf.h is illustrated in
+contrib/pngminim/*. See the "$(PNGCONF):" target in the makefile and
+pngusr.dfa in these directories.
+
+C. Configuration using PNG_USER_CONFIG
+
+If \-DPNG_USER_CONFIG is added to the CPPFLAGS when pnglibconf.h is built,
+the file pngusr.h will automatically be included before the options in
+scripts/pnglibconf.dfa are processed. Your pngusr.h file should contain only
+macro definitions turning features on or off or setting settings.
+
+Apart from the global setting "everything = off" all the options listed above
+can be set using macros in pngusr.h:
+
+#define PNG_feature_SUPPORTED
+
+is equivalent to:
+
+option feature on
+
+#define PNG_NO_feature
+
+is equivalent to:
+
+option feature off
+
+#define PNG_feature value
+
+is equivalent to:
+
+setting feature default value
+
+Notice that in both cases, pngusr.dfa and pngusr.h, the contents of the
+pngusr file you supply override the contents of scripts/pnglibconf.dfa
+
+If confusing or incomprehensible behavior results it is possible to
+examine the intermediate file pnglibconf.dfn to find the full set of
+dependency information for each setting and option. Simply locate the
+feature in the file and read the C comments that precede it.
+
+This method is also illustrated in the contrib/pngminim/* makefiles and
+pngusr.h.
+
+.SH III. Reading
+
+We'll now walk you through the possible functions to call when reading
+in a PNG file sequentially, briefly explaining the syntax and purpose
+of each one. See example.c and png.h for more detail. While
+progressive reading is covered in the next section, you will still
+need some of the functions discussed in this section to read a PNG
+file.
+
+.SS Setup
+
+You will want to do the I/O initialization(*) before you get into libpng,
+so if it doesn't work, you don't have much to undo. Of course, you
+will also want to insure that you are, in fact, dealing with a PNG
+file. Libpng provides a simple check to see if a file is a PNG file.
+To use it, pass in the first 1 to 8 bytes of the file to the function
+png_sig_cmp(), and it will return 0 (false) if the bytes match the
+corresponding bytes of the PNG signature, or nonzero (true) otherwise.
+Of course, the more bytes you pass in, the greater the accuracy of the
+prediction.
+
+If you are intending to keep the file pointer open for use in libpng,
+you must ensure you don't read more than 8 bytes from the beginning
+of the file, and you also have to make a call to png_set_sig_bytes()
+with the number of bytes you read from the beginning. Libpng will
+then only check the bytes (if any) that your program didn't read.
+
+(*): If you are not using the standard I/O functions, you will need
+to replace them with custom functions. See the discussion under
+Customizing libpng.
+
+ FILE *fp = fopen(file_name, "rb");
+ if (!fp)
+ {
+ return (ERROR);
+ }
+
+ if (fread(header, 1, number, fp) != number)
+ {
+ return (ERROR);
+ }
+
+ is_png = !png_sig_cmp(header, 0, number);
+ if (!is_png)
+ {
+ return (NOT_PNG);
+ }
+
+Next, png_struct and png_info need to be allocated and initialized. In
+order to ensure that the size of these structures is correct even with a
+dynamically linked libpng, there are functions to initialize and
+allocate the structures. We also pass the library version, optional
+pointers to error handling functions, and a pointer to a data struct for
+use by the error functions, if necessary (the pointer and functions can
+be NULL if the default error handlers are to be used). See the section
+on Changes to Libpng below regarding the old initialization functions.
+The structure allocation functions quietly return NULL if they fail to
+create the structure, so your application should check for that.
+
+ png_structp png_ptr = png_create_read_struct
+ (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+ user_error_fn, user_warning_fn);
+
+ if (!png_ptr)
+ return (ERROR);
+
+ png_infop info_ptr = png_create_info_struct(png_ptr);
+
+ if (!info_ptr)
+ {
+ png_destroy_read_struct(&png_ptr,
+ (png_infopp)NULL, (png_infopp)NULL);
+ return (ERROR);
+ }
+
+If you want to use your own memory allocation routines,
+use a libpng that was built with PNG_USER_MEM_SUPPORTED defined, and use
+png_create_read_struct_2() instead of png_create_read_struct():
+
+ png_structp png_ptr = png_create_read_struct_2
+ (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+ user_error_fn, user_warning_fn, (png_voidp)
+ user_mem_ptr, user_malloc_fn, user_free_fn);
+
+The error handling routines passed to png_create_read_struct()
+and the memory alloc/free routines passed to png_create_struct_2()
+are only necessary if you are not using the libpng supplied error
+handling and memory alloc/free functions.
+
+When libpng encounters an error, it expects to longjmp back
+to your routine. Therefore, you will need to call setjmp and pass
+your png_jmpbuf(png_ptr). If you read the file from different
+routines, you will need to update the longjmp buffer every time you enter
+a new routine that will call a png_*() function.
+
+See your documentation of setjmp/longjmp for your compiler for more
+information on setjmp/longjmp. See the discussion on libpng error
+handling in the Customizing Libpng section below for more information
+on the libpng error handling. If an error occurs, and libpng longjmp's
+back to your setjmp, you will want to call png_destroy_read_struct() to
+free any memory.
+
+ if (setjmp(png_jmpbuf(png_ptr)))
+ {
+ png_destroy_read_struct(&png_ptr, &info_ptr,
+ &end_info);
+ fclose(fp);
+ return (ERROR);
+ }
+
+Pass (png_infopp)NULL instead of &end_info if you didn't create
+an end_info structure.
+
+If you would rather avoid the complexity of setjmp/longjmp issues,
+you can compile libpng with PNG_NO_SETJMP, in which case
+errors will result in a call to PNG_ABORT() which defaults to abort().
+
+You can #define PNG_ABORT() to a function that does something
+more useful than abort(), as long as your function does not
+return.
+
+Now you need to set up the input code. The default for libpng is to
+use the C function fread(). If you use this, you will need to pass a
+valid FILE * in the function png_init_io(). Be sure that the file is
+opened in binary mode. If you wish to handle reading data in another
+way, you need not call the png_init_io() function, but you must then
+implement the libpng I/O methods discussed in the Customizing Libpng
+section below.
+
+ png_init_io(png_ptr, fp);
+
+If you had previously opened the file and read any of the signature from
+the beginning in order to see if this was a PNG file, you need to let
+libpng know that there are some bytes missing from the start of the file.
+
+ png_set_sig_bytes(png_ptr, number);
+
+You can change the zlib compression buffer size to be used while
+reading compressed data with
+
+ png_set_compression_buffer_size(png_ptr, buffer_size);
+
+where the default size is 8192 bytes. Note that the buffer size
+is changed immediately and the buffer is reallocated immediately,
+instead of setting a flag to be acted upon later.
+
+If you want CRC errors to be handled in a different manner than
+the default, use
+
+ png_set_crc_action(png_ptr, crit_action, ancil_action);
+
+The values for png_set_crc_action() say how libpng is to handle CRC errors in
+ancillary and critical chunks, and whether to use the data contained
+therein. Note that it is impossible to "discard" data in a critical
+chunk.
+
+Choices for (int) crit_action are
+ PNG_CRC_DEFAULT 0 error/quit
+ PNG_CRC_ERROR_QUIT 1 error/quit
+ PNG_CRC_WARN_USE 3 warn/use data
+ PNG_CRC_QUIET_USE 4 quiet/use data
+ PNG_CRC_NO_CHANGE 5 use the current value
+
+Choices for (int) ancil_action are
+ PNG_CRC_DEFAULT 0 error/quit
+ PNG_CRC_ERROR_QUIT 1 error/quit
+ PNG_CRC_WARN_DISCARD 2 warn/discard data
+ PNG_CRC_WARN_USE 3 warn/use data
+ PNG_CRC_QUIET_USE 4 quiet/use data
+ PNG_CRC_NO_CHANGE 5 use the current value
+
+.SS Setting up callback code
+
+You can set up a callback function to handle any unknown chunks in the
+input stream. You must supply the function
+
+ read_chunk_callback(png_structp png_ptr,
+ png_unknown_chunkp chunk);
+ {
+ /* The unknown chunk structure contains your
+ chunk data, along with similar data for any other
+ unknown chunks: */
+
+ png_byte name[5];
+ png_byte *data;
+ png_size_t size;
+
+ /* Note that libpng has already taken care of
+ the CRC handling */
+
+ /* put your code here. Search for your chunk in the
+ unknown chunk structure, process it, and return one
+ of the following: */
+
+ return (\-n); /* chunk had an error */
+ return (0); /* did not recognize */
+ return (n); /* success */
+ }
+
+(You can give your function another name that you like instead of
+"read_chunk_callback")
+
+To inform libpng about your function, use
+
+ png_set_read_user_chunk_fn(png_ptr, user_chunk_ptr,
+ read_chunk_callback);
+
+This names not only the callback function, but also a user pointer that
+you can retrieve with
+
+ png_get_user_chunk_ptr(png_ptr);
+
+If you call the png_set_read_user_chunk_fn() function, then all unknown
+chunks which the callback does not handle will be saved when read. You can
+cause them to be discarded by returning '1' ("handled") instead of '0'. This
+behavior will change in libpng 1.7 and the default handling set by the
+png_set_keep_unknown_chunks() function, described below, will be used when the
+callback returns 0. If you want the existing behavior you should set the global
+default to PNG_HANDLE_CHUNK_IF_SAFE now; this is compatible with all current
+versions of libpng and with 1.7. Libpng 1.6 issues a warning if you keep the
+default, or PNG_HANDLE_CHUNK_NEVER, and the callback returns 0.
+
+At this point, you can set up a callback function that will be
+called after each row has been read, which you can use to control
+a progress meter or the like. It's demonstrated in pngtest.c.
+You must supply a function
+
+ void read_row_callback(png_structp png_ptr,
+ png_uint_32 row, int pass);
+ {
+ /* put your code here */
+ }
+
+(You can give it another name that you like instead of "read_row_callback")
+
+To inform libpng about your function, use
+
+ png_set_read_status_fn(png_ptr, read_row_callback);
+
+When this function is called the row has already been completely processed and
+the 'row' and 'pass' refer to the next row to be handled. For the
+non-interlaced case the row that was just handled is simply one less than the
+passed in row number, and pass will always be 0. For the interlaced case the
+same applies unless the row value is 0, in which case the row just handled was
+the last one from one of the preceding passes. Because interlacing may skip a
+pass you cannot be sure that the preceding pass is just 'pass\-1', if you really
+need to know what the last pass is record (row,pass) from the callback and use
+the last recorded value each time.
+
+As with the user transform you can find the output row using the
+PNG_ROW_FROM_PASS_ROW macro.
+
+.SS Unknown-chunk handling
+
+Now you get to set the way the library processes unknown chunks in the
+input PNG stream. Both known and unknown chunks will be read. Normal
+behavior is that known chunks will be parsed into information in
+various info_ptr members while unknown chunks will be discarded. This
+behavior can be wasteful if your application will never use some known
+chunk types. To change this, you can call:
+
+ png_set_keep_unknown_chunks(png_ptr, keep,
+ chunk_list, num_chunks);
+
+ keep - 0: default unknown chunk handling
+ 1: ignore; do not keep
+ 2: keep only if safe-to-copy
+ 3: keep even if unsafe-to-copy
+
+ You can use these definitions:
+ PNG_HANDLE_CHUNK_AS_DEFAULT 0
+ PNG_HANDLE_CHUNK_NEVER 1
+ PNG_HANDLE_CHUNK_IF_SAFE 2
+ PNG_HANDLE_CHUNK_ALWAYS 3
+
+ chunk_list - list of chunks affected (a byte string,
+ five bytes per chunk, NULL or '\0' if
+ num_chunks is positive; ignored if
+ numchunks <= 0).
+
+ num_chunks - number of chunks affected; if 0, all
+ unknown chunks are affected. If positive,
+ only the chunks in the list are affected,
+ and if negative all unknown chunks and
+ all known chunks except for the IHDR,
+ PLTE, tRNS, IDAT, and IEND chunks are
+ affected.
+
+Unknown chunks declared in this way will be saved as raw data onto a
+list of png_unknown_chunk structures. If a chunk that is normally
+known to libpng is named in the list, it will be handled as unknown,
+according to the "keep" directive. If a chunk is named in successive
+instances of png_set_keep_unknown_chunks(), the final instance will
+take precedence. The IHDR and IEND chunks should not be named in
+chunk_list; if they are, libpng will process them normally anyway.
+If you know that your application will never make use of some particular
+chunks, use PNG_HANDLE_CHUNK_NEVER (or 1) as demonstrated below.
+
+Here is an example of the usage of png_set_keep_unknown_chunks(),
+where the private "vpAg" chunk will later be processed by a user chunk
+callback function:
+
+ png_byte vpAg[5]={118, 112, 65, 103, (png_byte) '\0'};
+
+ #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
+ png_byte unused_chunks[]=
+ {
+ 104, 73, 83, 84, (png_byte) '\0', /* hIST */
+ 105, 84, 88, 116, (png_byte) '\0', /* iTXt */
+ 112, 67, 65, 76, (png_byte) '\0', /* pCAL */
+ 115, 67, 65, 76, (png_byte) '\0', /* sCAL */
+ 115, 80, 76, 84, (png_byte) '\0', /* sPLT */
+ 116, 73, 77, 69, (png_byte) '\0', /* tIME */
+ };
+ #endif
+
+ ...
+
+ #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
+ /* ignore all unknown chunks
+ * (use global setting "2" for libpng16 and earlier):
+ */
+ png_set_keep_unknown_chunks(read_ptr, 2, NULL, 0);
+
+ /* except for vpAg: */
+ png_set_keep_unknown_chunks(read_ptr, 2, vpAg, 1);
+
+ /* also ignore unused known chunks: */
+ png_set_keep_unknown_chunks(read_ptr, 1, unused_chunks,
+ (int)(sizeof unused_chunks)/5);
+ #endif
+
+.SS User limits
+
+The PNG specification allows the width and height of an image to be as
+large as 2^(31\-1 (0x7fffffff), or about 2.147 billion rows and columns.
+For safety, libpng imposes a default limit of 1 million rows and columns.
+Larger images will be rejected immediately with a png_error() call. If
+you wish to change these limits, you can use
+
+ png_set_user_limits(png_ptr, width_max, height_max);
+
+to set your own limits (libpng may reject some very wide images
+anyway because of potential buffer overflow conditions).
+
+You should put this statement after you create the PNG structure and
+before calling png_read_info(), png_read_png(), or png_process_data().
+
+When writing a PNG datastream, put this statement before calling
+png_write_info() or png_write_png().
+
+If you need to retrieve the limits that are being applied, use
+
+ width_max = png_get_user_width_max(png_ptr);
+ height_max = png_get_user_height_max(png_ptr);
+
+The PNG specification sets no limit on the number of ancillary chunks
+allowed in a PNG datastream. By default, libpng imposes a limit of
+a total of 1000 sPLT, tEXt, iTXt, zTXt, and unknown chunks to be stored.
+If you have set up both info_ptr and end_info_ptr, the limit applies
+separately to each. You can change the limit on the total number of such
+chunks that will be stored, with
+
+ png_set_chunk_cache_max(png_ptr, user_chunk_cache_max);
+
+where 0x7fffffffL means unlimited. You can retrieve this limit with
+
+ chunk_cache_max = png_get_chunk_cache_max(png_ptr);
+
+Libpng imposes a limit of 8 Megabytes (8,000,000 bytes) on the amount of
+memory that a compressed chunk other than IDAT can occupy, when decompressed.
+You can change this limit with
+
+ png_set_chunk_malloc_max(png_ptr, user_chunk_malloc_max);
+
+and you can retrieve the limit with
+
+ chunk_malloc_max = png_get_chunk_malloc_max(png_ptr);
+
+Any chunks that would cause either of these limits to be exceeded will
+be ignored.
+
+.SS Information about your system
+
+If you intend to display the PNG or to incorporate it in other image data you
+need to tell libpng information about your display or drawing surface so that
+libpng can convert the values in the image to match the display.
+
+From libpng-1.5.4 this information can be set before reading the PNG file
+header. In earlier versions png_set_gamma() existed but behaved incorrectly if
+called before the PNG file header had been read and png_set_alpha_mode() did not
+exist.
+
+If you need to support versions prior to libpng-1.5.4 test the version number
+as illustrated below using "PNG_LIBPNG_VER >= 10504" and follow the procedures
+described in the appropriate manual page.
+
+You give libpng the encoding expected by your system expressed as a 'gamma'
+value. You can also specify a default encoding for the PNG file in
+case the required information is missing from the file. By default libpng
+assumes that the PNG data matches your system, to keep this default call:
+
+ png_set_gamma(png_ptr, screen_gamma, output_gamma);
+
+or you can use the fixed point equivalent:
+
+ png_set_gamma_fixed(png_ptr, PNG_FP_1*screen_gamma,
+ PNG_FP_1*output_gamma);
+
+If you don't know the gamma for your system it is probably 2.2 - a good
+approximation to the IEC standard for display systems (sRGB). If images are
+too contrasty or washed out you got the value wrong - check your system
+documentation!
+
+Many systems permit the system gamma to be changed via a lookup table in the
+display driver, a few systems, including older Macs, change the response by
+default. As of 1.5.4 three special values are available to handle common
+situations:
+
+ PNG_DEFAULT_sRGB: Indicates that the system conforms to the
+ IEC 61966-2-1 standard. This matches almost
+ all systems.
+ PNG_GAMMA_MAC_18: Indicates that the system is an older
+ (pre Mac OS 10.6) Apple Macintosh system with
+ the default settings.
+ PNG_GAMMA_LINEAR: Just the fixed point value for 1.0 - indicates
+ that the system expects data with no gamma
+ encoding.
+
+You would use the linear (unencoded) value if you need to process the pixel
+values further because this avoids the need to decode and re-encode each
+component value whenever arithmetic is performed. A lot of graphics software
+uses linear values for this reason, often with higher precision component values
+to preserve overall accuracy.
+
+
+The output_gamma value expresses how to decode the output values, not how
+they are encoded. The values used correspond to the normal numbers used to
+describe the overall gamma of a computer display system; for example 2.2 for
+an sRGB conformant system. The values are scaled by 100000 in the _fixed
+version of the API (so 220000 for sRGB.)
+
+The inverse of the value is always used to provide a default for the PNG file
+encoding if it has no gAMA chunk and if png_set_gamma() has not been called
+to override the PNG gamma information.
+
+When the ALPHA_OPTIMIZED mode is selected the output gamma is used to encode
+opaque pixels however pixels with lower alpha values are not encoded,
+regardless of the output gamma setting.
+
+When the standard Porter Duff handling is requested with mode 1 the output
+encoding is set to be linear and the output_gamma value is only relevant
+as a default for input data that has no gamma information. The linear output
+encoding will be overridden if png_set_gamma() is called - the results may be
+highly unexpected!
+
+The following numbers are derived from the sRGB standard and the research
+behind it. sRGB is defined to be approximated by a PNG gAMA chunk value of
+0.45455 (1/2.2) for PNG. The value implicitly includes any viewing
+correction required to take account of any differences in the color
+environment of the original scene and the intended display environment; the
+value expresses how to *decode* the image for display, not how the original
+data was *encoded*.
+
+sRGB provides a peg for the PNG standard by defining a viewing environment.
+sRGB itself, and earlier TV standards, actually use a more complex transform
+(a linear portion then a gamma 2.4 power law) than PNG can express. (PNG is
+limited to simple power laws.) By saying that an image for direct display on
+an sRGB conformant system should be stored with a gAMA chunk value of 45455
+(11.3.3.2 and 11.3.3.5 of the ISO PNG specification) the PNG specification
+makes it possible to derive values for other display systems and
+environments.
+
+The Mac value is deduced from the sRGB based on an assumption that the actual
+extra viewing correction used in early Mac display systems was implemented as
+a power 1.45 lookup table.
+
+Any system where a programmable lookup table is used or where the behavior of
+the final display device characteristics can be changed requires system
+specific code to obtain the current characteristic. However this can be
+difficult and most PNG gamma correction only requires an approximate value.
+
+By default, if png_set_alpha_mode() is not called, libpng assumes that all
+values are unencoded, linear, values and that the output device also has a
+linear characteristic. This is only very rarely correct - it is invariably
+better to call png_set_alpha_mode() with PNG_DEFAULT_sRGB than rely on the
+default if you don't know what the right answer is!
+
+The special value PNG_GAMMA_MAC_18 indicates an older Mac system (pre Mac OS
+10.6) which used a correction table to implement a somewhat lower gamma on an
+otherwise sRGB system.
+
+Both these values are reserved (not simple gamma values) in order to allow
+more precise correction internally in the future.
+
+NOTE: the values can be passed to either the fixed or floating
+point APIs, but the floating point API will also accept floating point
+values.
+
+The second thing you may need to tell libpng about is how your system handles
+alpha channel information. Some, but not all, PNG files contain an alpha
+channel. To display these files correctly you need to compose the data onto a
+suitable background, as described in the PNG specification.
+
+Libpng only supports composing onto a single color (using png_set_background;
+see below). Otherwise you must do the composition yourself and, in this case,
+you may need to call png_set_alpha_mode:
+
+ #if PNG_LIBPNG_VER >= 10504
+ png_set_alpha_mode(png_ptr, mode, screen_gamma);
+ #else
+ png_set_gamma(png_ptr, screen_gamma, 1.0/screen_gamma);
+ #endif
+
+The screen_gamma value is the same as the argument to png_set_gamma; however,
+how it affects the output depends on the mode. png_set_alpha_mode() sets the
+file gamma default to 1/screen_gamma, so normally you don't need to call
+png_set_gamma. If you need different defaults call png_set_gamma() before
+png_set_alpha_mode() - if you call it after it will override the settings made
+by png_set_alpha_mode().
+
+The mode is as follows:
+
+ PNG_ALPHA_PNG: The data is encoded according to the PNG
+specification. Red, green and blue, or gray, components are
+gamma encoded color values and are not premultiplied by the
+alpha value. The alpha value is a linear measure of the
+contribution of the pixel to the corresponding final output pixel.
+
+You should normally use this format if you intend to perform
+color correction on the color values; most, maybe all, color
+correction software has no handling for the alpha channel and,
+anyway, the math to handle pre-multiplied component values is
+unnecessarily complex.
+
+Before you do any arithmetic on the component values you need
+to remove the gamma encoding and multiply out the alpha
+channel. See the PNG specification for more detail. It is
+important to note that when an image with an alpha channel is
+scaled, linear encoded, pre-multiplied component values must
+be used!
+
+The remaining modes assume you don't need to do any further color correction or
+that if you do, your color correction software knows all about alpha (it
+probably doesn't!). They 'associate' the alpha with the color information by
+storing color channel values that have been scaled by the alpha. The
+advantage is that the color channels can be resampled (the image can be
+scaled) in this form. The disadvantage is that normal practice is to store
+linear, not (gamma) encoded, values and this requires 16-bit channels for
+still images rather than the 8-bit channels that are just about sufficient if
+gamma encoding is used. In addition all non-transparent pixel values,
+including completely opaque ones, must be gamma encoded to produce the final
+image. These are the 'STANDARD', 'ASSOCIATED' or 'PREMULTIPLIED' modes
+described below (the latter being the two common names for associated alpha
+color channels). Note that PNG files always contain non-associated color
+channels; png_set_alpha_mode() with one of the modes causes the decoder to
+convert the pixels to an associated form before returning them to your
+application.
+
+Since it is not necessary to perform arithmetic on opaque color values so
+long as they are not to be resampled and are in the final color space it is
+possible to optimize the handling of alpha by storing the opaque pixels in
+the PNG format (adjusted for the output color space) while storing partially
+opaque pixels in the standard, linear, format. The accuracy required for
+standard alpha composition is relatively low, because the pixels are
+isolated, therefore typically the accuracy loss in storing 8-bit linear
+values is acceptable. (This is not true if the alpha channel is used to
+simulate transparency over large areas - use 16 bits or the PNG mode in
+this case!) This is the 'OPTIMIZED' mode. For this mode a pixel is
+treated as opaque only if the alpha value is equal to the maximum value.
+
+ PNG_ALPHA_STANDARD: The data libpng produces is encoded in the
+standard way assumed by most correctly written graphics software.
+The gamma encoding will be removed by libpng and the
+linear component values will be pre-multiplied by the
+alpha channel.
+
+With this format the final image must be re-encoded to
+match the display gamma before the image is displayed.
+If your system doesn't do that, yet still seems to
+perform arithmetic on the pixels without decoding them,
+it is broken - check out the modes below.
+
+With PNG_ALPHA_STANDARD libpng always produces linear
+component values, whatever screen_gamma you supply. The
+screen_gamma value is, however, used as a default for
+the file gamma if the PNG file has no gamma information.
+
+If you call png_set_gamma() after png_set_alpha_mode() you
+will override the linear encoding. Instead the
+pre-multiplied pixel values will be gamma encoded but
+the alpha channel will still be linear. This may
+actually match the requirements of some broken software,
+but it is unlikely.
+
+While linear 8-bit data is often used it has
+insufficient precision for any image with a reasonable
+dynamic range. To avoid problems, and if your software
+supports it, use png_set_expand_16() to force all
+components to 16 bits.
+
+ PNG_ALPHA_OPTIMIZED: This mode is the same as PNG_ALPHA_STANDARD
+except that completely opaque pixels are gamma encoded according to
+the screen_gamma value. Pixels with alpha less than 1.0
+will still have linear components.
+
+Use this format if you have control over your
+compositing software and so don't do other arithmetic
+(such as scaling) on the data you get from libpng. Your
+compositing software can simply copy opaque pixels to
+the output but still has linear values for the
+non-opaque pixels.
+
+In normal compositing, where the alpha channel encodes
+partial pixel coverage (as opposed to broad area
+translucency), the inaccuracies of the 8-bit
+representation of non-opaque pixels are irrelevant.
+
+You can also try this format if your software is broken;
+it might look better.
+
+ PNG_ALPHA_BROKEN: This is PNG_ALPHA_STANDARD; however, all component
+values, including the alpha channel are gamma encoded. This is
+broken because, in practice, no implementation that uses this choice
+correctly undoes the encoding before handling alpha composition. Use this
+choice only if other serious errors in the software or hardware you use
+mandate it. In most cases of broken software or hardware the bug in the
+final display manifests as a subtle halo around composited parts of the
+image. You may not even perceive this as a halo; the composited part of
+the image may simply appear separate from the background, as though it had
+been cut out of paper and pasted on afterward.
+
+If you don't have to deal with bugs in software or hardware, or if you can fix
+them, there are three recommended ways of using png_set_alpha_mode():
+
+ png_set_alpha_mode(png_ptr, PNG_ALPHA_PNG,
+ screen_gamma);
+
+You can do color correction on the result (libpng does not currently
+support color correction internally). When you handle the alpha channel
+you need to undo the gamma encoding and multiply out the alpha.
+
+ png_set_alpha_mode(png_ptr, PNG_ALPHA_STANDARD,
+ screen_gamma);
+ png_set_expand_16(png_ptr);
+
+If you are using the high level interface, don't call png_set_expand_16();
+instead pass PNG_TRANSFORM_EXPAND_16 to the interface.
+
+With this mode you can't do color correction, but you can do arithmetic,
+including composition and scaling, on the data without further processing.
+
+ png_set_alpha_mode(png_ptr, PNG_ALPHA_OPTIMIZED,
+ screen_gamma);
+
+You can avoid the expansion to 16-bit components with this mode, but you
+lose the ability to scale the image or perform other linear arithmetic.
+All you can do is compose the result onto a matching output. Since this
+mode is libpng-specific you also need to write your own composition
+software.
+
+The following are examples of calls to png_set_alpha_mode to achieve the
+required overall gamma correction and, where necessary, alpha
+premultiplication.
+
+ png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
+
+This is the default libpng handling of the alpha channel - it is not
+pre-multiplied into the color components. In addition the call states
+that the output is for a sRGB system and causes all PNG files without gAMA
+chunks to be assumed to be encoded using sRGB.
+
+ png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
+
+In this case the output is assumed to be something like an sRGB conformant
+display preceeded by a power-law lookup table of power 1.45. This is how
+early Mac systems behaved.
+
+ png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_GAMMA_LINEAR);
+
+This is the classic Jim Blinn approach and will work in academic
+environments where everything is done by the book. It has the shortcoming
+of assuming that input PNG data with no gamma information is linear - this
+is unlikely to be correct unless the PNG files where generated locally.
+Most of the time the output precision will be so low as to show
+significant banding in dark areas of the image.
+
+ png_set_expand_16(pp);
+ png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_DEFAULT_sRGB);
+
+This is a somewhat more realistic Jim Blinn inspired approach. PNG files
+are assumed to have the sRGB encoding if not marked with a gamma value and
+the output is always 16 bits per component. This permits accurate scaling
+and processing of the data. If you know that your input PNG files were
+generated locally you might need to replace PNG_DEFAULT_sRGB with the
+correct value for your system.
+
+ png_set_alpha_mode(pp, PNG_ALPHA_OPTIMIZED, PNG_DEFAULT_sRGB);
+
+If you just need to composite the PNG image onto an existing background
+and if you control the code that does this you can use the optimization
+setting. In this case you just copy completely opaque pixels to the
+output. For pixels that are not completely transparent (you just skip
+those) you do the composition math using png_composite or png_composite_16
+below then encode the resultant 8-bit or 16-bit values to match the output
+encoding.
+
+ Other cases
+
+If neither the PNG nor the standard linear encoding work for you because
+of the software or hardware you use then you have a big problem. The PNG
+case will probably result in halos around the image. The linear encoding
+will probably result in a washed out, too bright, image (it's actually too
+contrasty.) Try the ALPHA_OPTIMIZED mode above - this will probably
+substantially reduce the halos. Alternatively try:
+
+ png_set_alpha_mode(pp, PNG_ALPHA_BROKEN, PNG_DEFAULT_sRGB);
+
+This option will also reduce the halos, but there will be slight dark
+halos round the opaque parts of the image where the background is light.
+In the OPTIMIZED mode the halos will be light halos where the background
+is dark. Take your pick - the halos are unavoidable unless you can get
+your hardware/software fixed! (The OPTIMIZED approach is slightly
+faster.)
+
+When the default gamma of PNG files doesn't match the output gamma.
+If you have PNG files with no gamma information png_set_alpha_mode allows
+you to provide a default gamma, but it also sets the ouput gamma to the
+matching value. If you know your PNG files have a gamma that doesn't
+match the output you can take advantage of the fact that
+png_set_alpha_mode always sets the output gamma but only sets the PNG
+default if it is not already set:
+
+ png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
+ png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
+
+The first call sets both the default and the output gamma values, the
+second call overrides the output gamma without changing the default. This
+is easier than achieving the same effect with png_set_gamma. You must use
+PNG_ALPHA_PNG for the first call - internal checking in png_set_alpha will
+fire if more than one call to png_set_alpha_mode and png_set_background is
+made in the same read operation, however multiple calls with PNG_ALPHA_PNG
+are ignored.
+
+If you don't need, or can't handle, the alpha channel you can call
+png_set_background() to remove it by compositing against a fixed color. Don't
+call png_set_strip_alpha() to do this - it will leave spurious pixel values in
+transparent parts of this image.
+
+ png_set_background(png_ptr, &background_color,
+ PNG_BACKGROUND_GAMMA_SCREEN, 0, 1);
+
+The background_color is an RGB or grayscale value according to the data format
+libpng will produce for you. Because you don't yet know the format of the PNG
+file, if you call png_set_background at this point you must arrange for the
+format produced by libpng to always have 8-bit or 16-bit components and then
+store the color as an 8-bit or 16-bit color as appropriate. The color contains
+separate gray and RGB component values, so you can let libpng produce gray or
+RGB output according to the input format, but low bit depth grayscale images
+must always be converted to at least 8-bit format. (Even though low bit depth
+grayscale images can't have an alpha channel they can have a transparent
+color!)
+
+You set the transforms you need later, either as flags to the high level
+interface or libpng API calls for the low level interface. For reference the
+settings and API calls required are:
+
+8-bit values:
+ PNG_TRANSFORM_SCALE_16 | PNG_EXPAND
+ png_set_expand(png_ptr); png_set_scale_16(png_ptr);
+
+ If you must get exactly the same inaccurate results
+ produced by default in versions prior to libpng-1.5.4,
+ use PNG_TRANSFORM_STRIP_16 and png_set_strip_16(png_ptr)
+ instead.
+
+16-bit values:
+ PNG_TRANSFORM_EXPAND_16
+ png_set_expand_16(png_ptr);
+
+In either case palette image data will be expanded to RGB. If you just want
+color data you can add PNG_TRANSFORM_GRAY_TO_RGB or png_set_gray_to_rgb(png_ptr)
+to the list.
+
+Calling png_set_background before the PNG file header is read will not work
+prior to libpng-1.5.4. Because the failure may result in unexpected warnings or
+errors it is therefore much safer to call png_set_background after the head has
+been read. Unfortunately this means that prior to libpng-1.5.4 it cannot be
+used with the high level interface.
+
+.SS The high-level read interface
+
+At this point there are two ways to proceed; through the high-level
+read interface, or through a sequence of low-level read operations.
+You can use the high-level interface if (a) you are willing to read
+the entire image into memory, and (b) the input transformations
+you want to do are limited to the following set:
+
+ PNG_TRANSFORM_IDENTITY No transformation
+ PNG_TRANSFORM_SCALE_16 Strip 16-bit samples to
+ 8-bit accurately
+ PNG_TRANSFORM_STRIP_16 Chop 16-bit samples to
+ 8-bit less accurately
+ PNG_TRANSFORM_STRIP_ALPHA Discard the alpha channel
+ PNG_TRANSFORM_PACKING Expand 1, 2 and 4-bit
+ samples to bytes
+ PNG_TRANSFORM_PACKSWAP Change order of packed
+ pixels to LSB first
+ PNG_TRANSFORM_EXPAND Perform set_expand()
+ PNG_TRANSFORM_INVERT_MONO Invert monochrome images
+ PNG_TRANSFORM_SHIFT Normalize pixels to the
+ sBIT depth
+ PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA
+ to BGRA
+ PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
+ to AG
+ PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
+ to transparency
+ PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
+ PNG_TRANSFORM_GRAY_TO_RGB Expand grayscale samples
+ to RGB (or GA to RGBA)
+ PNG_TRANSFORM_EXPAND_16 Expand samples to 16 bits
+
+(This excludes setting a background color, doing gamma transformation,
+quantizing, and setting filler.) If this is the case, simply do this:
+
+ png_read_png(png_ptr, info_ptr, png_transforms, NULL)
+
+where png_transforms is an integer containing the bitwise OR of some
+set of transformation flags. This call is equivalent to png_read_info(),
+followed the set of transformations indicated by the transform mask,
+then png_read_image(), and finally png_read_end().
+
+(The final parameter of this call is not yet used. Someday it might point
+to transformation parameters required by some future input transform.)
+
+You must use png_transforms and not call any png_set_transform() functions
+when you use png_read_png().
+
+After you have called png_read_png(), you can retrieve the image data
+with
+
+ row_pointers = png_get_rows(png_ptr, info_ptr);
+
+where row_pointers is an array of pointers to the pixel data for each row:
+
+ png_bytep row_pointers[height];
+
+If you know your image size and pixel size ahead of time, you can allocate
+row_pointers prior to calling png_read_png() with
+
+ if (height > PNG_UINT_32_MAX/(sizeof (png_byte)))
+ png_error (png_ptr,
+ "Image is too tall to process in memory");
+
+ if (width > PNG_UINT_32_MAX/pixel_size)
+ png_error (png_ptr,
+ "Image is too wide to process in memory");
+
+ row_pointers = png_malloc(png_ptr,
+ height*(sizeof (png_bytep)));
+
+ for (int i=0; i<height, i++)
+ row_pointers[i]=NULL; /* security precaution */
+
+ for (int i=0; i<height, i++)
+ row_pointers[i]=png_malloc(png_ptr,
+ width*pixel_size);
+
+ png_set_rows(png_ptr, info_ptr, &row_pointers);
+
+Alternatively you could allocate your image in one big block and define
+row_pointers[i] to point into the proper places in your block.
+
+If you use png_set_rows(), the application is responsible for freeing
+row_pointers (and row_pointers[i], if they were separately allocated).
+
+If you don't allocate row_pointers ahead of time, png_read_png() will
+do it, and it'll be free'ed by libpng when you call png_destroy_*().
+
+.SS The low-level read interface
+
+If you are going the low-level route, you are now ready to read all
+the file information up to the actual image data. You do this with a
+call to png_read_info().
+
+ png_read_info(png_ptr, info_ptr);
+
+This will process all chunks up to but not including the image data.
+
+This also copies some of the data from the PNG file into the decode structure
+for use in later transformations. Important information copied in is:
+
+1) The PNG file gamma from the gAMA chunk. This overwrites the default value
+provided by an earlier call to png_set_gamma or png_set_alpha_mode.
+
+2) Prior to libpng-1.5.4 the background color from a bKGd chunk. This
+damages the information provided by an earlier call to png_set_background
+resulting in unexpected behavior. Libpng-1.5.4 no longer does this.
+
+3) The number of significant bits in each component value. Libpng uses this to
+optimize gamma handling by reducing the internal lookup table sizes.
+
+4) The transparent color information from a tRNS chunk. This can be modified by
+a later call to png_set_tRNS.
+
+.SS Querying the info structure
+
+Functions are used to get the information from the info_ptr once it
+has been read. Note that these fields may not be completely filled
+in until png_read_end() has read the chunk data following the image.
+
+ png_get_IHDR(png_ptr, info_ptr, &width, &height,
+ &bit_depth, &color_type, &interlace_type,
+ &compression_type, &filter_method);
+
+ width - holds the width of the image
+ in pixels (up to 2^31).
+
+ height - holds the height of the image
+ in pixels (up to 2^31).
+
+ bit_depth - holds the bit depth of one of the
+ image channels. (valid values are
+ 1, 2, 4, 8, 16 and depend also on
+ the color_type. See also
+ significant bits (sBIT) below).
+
+ color_type - describes which color/alpha channels
+ are present.
+ PNG_COLOR_TYPE_GRAY
+ (bit depths 1, 2, 4, 8, 16)
+ PNG_COLOR_TYPE_GRAY_ALPHA
+ (bit depths 8, 16)
+ PNG_COLOR_TYPE_PALETTE
+ (bit depths 1, 2, 4, 8)
+ PNG_COLOR_TYPE_RGB
+ (bit_depths 8, 16)
+ PNG_COLOR_TYPE_RGB_ALPHA
+ (bit_depths 8, 16)
+
+ PNG_COLOR_MASK_PALETTE
+ PNG_COLOR_MASK_COLOR
+ PNG_COLOR_MASK_ALPHA
+
+ interlace_type - (PNG_INTERLACE_NONE or
+ PNG_INTERLACE_ADAM7)
+
+ compression_type - (must be PNG_COMPRESSION_TYPE_BASE
+ for PNG 1.0)
+
+ filter_method - (must be PNG_FILTER_TYPE_BASE
+ for PNG 1.0, and can also be
+ PNG_INTRAPIXEL_DIFFERENCING if
+ the PNG datastream is embedded in
+ a MNG-1.0 datastream)
+
+ Any of width, height, color_type, bit_depth,
+ interlace_type, compression_type, or filter_method can
+ be NULL if you are not interested in their values.
+
+ Note that png_get_IHDR() returns 32-bit data into
+ the application's width and height variables.
+ This is an unsafe situation if these are not png_uint_32
+ variables. In such situations, the
+ png_get_image_width() and png_get_image_height()
+ functions described below are safer.
+
+ width = png_get_image_width(png_ptr,
+ info_ptr);
+
+ height = png_get_image_height(png_ptr,
+ info_ptr);
+
+ bit_depth = png_get_bit_depth(png_ptr,
+ info_ptr);
+
+ color_type = png_get_color_type(png_ptr,
+ info_ptr);
+
+ interlace_type = png_get_interlace_type(png_ptr,
+ info_ptr);
+
+ compression_type = png_get_compression_type(png_ptr,
+ info_ptr);
+
+ filter_method = png_get_filter_type(png_ptr,
+ info_ptr);
+
+ channels = png_get_channels(png_ptr, info_ptr);
+
+ channels - number of channels of info for the
+ color type (valid values are 1 (GRAY,
+ PALETTE), 2 (GRAY_ALPHA), 3 (RGB),
+ 4 (RGB_ALPHA or RGB + filler byte))
+
+ rowbytes = png_get_rowbytes(png_ptr, info_ptr);
+
+ rowbytes - number of bytes needed to hold a row
+
+ signature = png_get_signature(png_ptr, info_ptr);
+
+ signature - holds the signature read from the
+ file (if any). The data is kept in
+ the same offset it would be if the
+ whole signature were read (i.e. if an
+ application had already read in 4
+ bytes of signature before starting
+ libpng, the remaining 4 bytes would
+ be in signature[4] through signature[7]
+ (see png_set_sig_bytes())).
+
+These are also important, but their validity depends on whether the chunk
+has been read. The png_get_valid(png_ptr, info_ptr, PNG_INFO_<chunk>) and
+png_get_<chunk>(png_ptr, info_ptr, ...) functions return non-zero if the
+data has been read, or zero if it is missing. The parameters to the
+png_get_<chunk> are set directly if they are simple data types, or a
+pointer into the info_ptr is returned for any complex types.
+
+The colorspace data from gAMA, cHRM, sRGB, iCCP, and sBIT chunks
+is simply returned to give the application information about how the
+image was encoded. Libpng itself only does transformations using the file
+gamma when combining semitransparent pixels with the background color, and,
+since libpng-1.6.0, when converting between 8-bit sRGB and 16-bit linear pixels
+within the simplified API. Libpng also uses the file gamma when converting
+RGB to gray, beginning with libpng-1.0.5, if the application calls
+png_set_rgb_to_gray()).
+
+ png_get_PLTE(png_ptr, info_ptr, &palette,
+ &num_palette);
+
+ palette - the palette for the file
+ (array of png_color)
+
+ num_palette - number of entries in the palette
+
+ png_get_gAMA(png_ptr, info_ptr, &file_gamma);
+ png_get_gAMA_fixed(png_ptr, info_ptr, &int_file_gamma);
+
+ file_gamma - the gamma at which the file is
+ written (PNG_INFO_gAMA)
+
+ int_file_gamma - 100,000 times the gamma at which the
+ file is written
+
+ png_get_cHRM(png_ptr, info_ptr, &white_x, &white_y, &red_x,
+ &red_y, &green_x, &green_y, &blue_x, &blue_y)
+ png_get_cHRM_XYZ(png_ptr, info_ptr, &red_X, &red_Y, &red_Z,
+ &green_X, &green_Y, &green_Z, &blue_X, &blue_Y,
+ &blue_Z)
+ png_get_cHRM_fixed(png_ptr, info_ptr, &int_white_x,
+ &int_white_y, &int_red_x, &int_red_y,
+ &int_green_x, &int_green_y, &int_blue_x,
+ &int_blue_y)
+ png_get_cHRM_XYZ_fixed(png_ptr, info_ptr, &int_red_X, &int_red_Y,
+ &int_red_Z, &int_green_X, &int_green_Y,
+ &int_green_Z, &int_blue_X, &int_blue_Y,
+ &int_blue_Z)
+
+ {white,red,green,blue}_{x,y}
+ A color space encoding specified using the
+ chromaticities of the end points and the
+ white point. (PNG_INFO_cHRM)
+
+ {red,green,blue}_{X,Y,Z}
+ A color space encoding specified using the
+ encoding end points - the CIE tristimulus
+ specification of the intended color of the red,
+ green and blue channels in the PNG RGB data.
+ The white point is simply the sum of the three
+ end points. (PNG_INFO_cHRM)
+
+ png_get_sRGB(png_ptr, info_ptr, &srgb_intent);
+
+ srgb_intent - the rendering intent (PNG_INFO_sRGB)
+ The presence of the sRGB chunk
+ means that the pixel data is in the
+ sRGB color space. This chunk also
+ implies specific values of gAMA and
+ cHRM.
+
+ png_get_iCCP(png_ptr, info_ptr, &name,
+ &compression_type, &profile, &proflen);
+
+ name - The profile name.
+
+ compression_type - The compression type; always
+ PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
+ You may give NULL to this argument to
+ ignore it.
+
+ profile - International Color Consortium color
+ profile data. May contain NULs.
+
+ proflen - length of profile data in bytes.
+
+ png_get_sBIT(png_ptr, info_ptr, &sig_bit);
+
+ sig_bit - the number of significant bits for
+ (PNG_INFO_sBIT) each of the gray,
+ red, green, and blue channels,
+ whichever are appropriate for the
+ given color type (png_color_16)
+
+ png_get_tRNS(png_ptr, info_ptr, &trans_alpha,
+ &num_trans, &trans_color);
+
+ trans_alpha - array of alpha (transparency)
+ entries for palette (PNG_INFO_tRNS)
+
+ num_trans - number of transparent entries
+ (PNG_INFO_tRNS)
+
+ trans_color - graylevel or color sample values of
+ the single transparent color for
+ non-paletted images (PNG_INFO_tRNS)
+
+ png_get_hIST(png_ptr, info_ptr, &hist);
+ (PNG_INFO_hIST)
+
+ hist - histogram of palette (array of
+ png_uint_16)
+
+ png_get_tIME(png_ptr, info_ptr, &mod_time);
+
+ mod_time - time image was last modified
+ (PNG_VALID_tIME)
+
+ png_get_bKGD(png_ptr, info_ptr, &background);
+
+ background - background color (of type
+ png_color_16p) (PNG_VALID_bKGD)
+ valid 16-bit red, green and blue
+ values, regardless of color_type
+
+ num_comments = png_get_text(png_ptr, info_ptr,
+ &text_ptr, &num_text);
+
+ num_comments - number of comments
+
+ text_ptr - array of png_text holding image
+ comments
+
+ text_ptr[i].compression - type of compression used
+ on "text" PNG_TEXT_COMPRESSION_NONE
+ PNG_TEXT_COMPRESSION_zTXt
+ PNG_ITXT_COMPRESSION_NONE
+ PNG_ITXT_COMPRESSION_zTXt
+
+ text_ptr[i].key - keyword for comment. Must contain
+ 1-79 characters.
+
+ text_ptr[i].text - text comments for current
+ keyword. Can be empty.
+
+ text_ptr[i].text_length - length of text string,
+ after decompression, 0 for iTXt
+
+ text_ptr[i].itxt_length - length of itxt string,
+ after decompression, 0 for tEXt/zTXt
+
+ text_ptr[i].lang - language of comment (empty
+ string for unknown).
+
+ text_ptr[i].lang_key - keyword in UTF-8
+ (empty string for unknown).
+
+ Note that the itxt_length, lang, and lang_key
+ members of the text_ptr structure only exist when the
+ library is built with iTXt chunk support. Prior to
+ libpng-1.4.0 the library was built by default without
+ iTXt support. Also note that when iTXt is supported,
+ they contain NULL pointers when the "compression"
+ field contains PNG_TEXT_COMPRESSION_NONE or
+ PNG_TEXT_COMPRESSION_zTXt.
+
+ num_text - number of comments (same as
+ num_comments; you can put NULL here
+ to avoid the duplication)
+
+ Note while png_set_text() will accept text, language,
+ and translated keywords that can be NULL pointers, the
+ structure returned by png_get_text will always contain
+ regular zero-terminated C strings. They might be
+ empty strings but they will never be NULL pointers.
+
+ num_spalettes = png_get_sPLT(png_ptr, info_ptr,
+ &palette_ptr);
+
+ num_spalettes - number of sPLT chunks read.
+
+ palette_ptr - array of palette structures holding
+ contents of one or more sPLT chunks
+ read.
+
+ png_get_oFFs(png_ptr, info_ptr, &offset_x, &offset_y,
+ &unit_type);
+
+ offset_x - positive offset from the left edge
+ of the screen (can be negative)
+
+ offset_y - positive offset from the top edge
+ of the screen (can be negative)
+
+ unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
+
+ png_get_pHYs(png_ptr, info_ptr, &res_x, &res_y,
+ &unit_type);
+
+ res_x - pixels/unit physical resolution in
+ x direction
+
+ res_y - pixels/unit physical resolution in
+ x direction
+
+ unit_type - PNG_RESOLUTION_UNKNOWN,
+ PNG_RESOLUTION_METER
+
+ png_get_sCAL(png_ptr, info_ptr, &unit, &width,
+ &height)
+
+ unit - physical scale units (an integer)
+
+ width - width of a pixel in physical scale units
+
+ height - height of a pixel in physical scale units
+ (width and height are doubles)
+
+ png_get_sCAL_s(png_ptr, info_ptr, &unit, &width,
+ &height)
+
+ unit - physical scale units (an integer)
+
+ width - width of a pixel in physical scale units
+ (expressed as a string)
+
+ height - height of a pixel in physical scale units
+ (width and height are strings like "2.54")
+
+ num_unknown_chunks = png_get_unknown_chunks(png_ptr,
+ info_ptr, &unknowns)
+
+ unknowns - array of png_unknown_chunk
+ structures holding unknown chunks
+
+ unknowns[i].name - name of unknown chunk
+
+ unknowns[i].data - data of unknown chunk
+
+ unknowns[i].size - size of unknown chunk's data
+
+ unknowns[i].location - position of chunk in file
+
+ The value of "i" corresponds to the order in which the
+ chunks were read from the PNG file or inserted with the
+ png_set_unknown_chunks() function.
+
+ The value of "location" is a bitwise "or" of
+
+ PNG_HAVE_IHDR (0x01)
+ PNG_HAVE_PLTE (0x02)
+ PNG_AFTER_IDAT (0x08)
+
+The data from the pHYs chunk can be retrieved in several convenient
+forms:
+
+ res_x = png_get_x_pixels_per_meter(png_ptr,
+ info_ptr)
+
+ res_y = png_get_y_pixels_per_meter(png_ptr,
+ info_ptr)
+
+ res_x_and_y = png_get_pixels_per_meter(png_ptr,
+ info_ptr)
+
+ res_x = png_get_x_pixels_per_inch(png_ptr,
+ info_ptr)
+
+ res_y = png_get_y_pixels_per_inch(png_ptr,
+ info_ptr)
+
+ res_x_and_y = png_get_pixels_per_inch(png_ptr,
+ info_ptr)
+
+ aspect_ratio = png_get_pixel_aspect_ratio(png_ptr,
+ info_ptr)
+
+ Each of these returns 0 [signifying "unknown"] if
+ the data is not present or if res_x is 0;
+ res_x_and_y is 0 if res_x != res_y
+
+ Note that because of the way the resolutions are
+ stored internally, the inch conversions won't
+ come out to exactly even number. For example,
+ 72 dpi is stored as 0.28346 pixels/meter, and
+ when this is retrieved it is 71.9988 dpi, so
+ be sure to round the returned value appropriately
+ if you want to display a reasonable-looking result.
+
+The data from the oFFs chunk can be retrieved in several convenient
+forms:
+
+ x_offset = png_get_x_offset_microns(png_ptr, info_ptr);
+
+ y_offset = png_get_y_offset_microns(png_ptr, info_ptr);
+
+ x_offset = png_get_x_offset_inches(png_ptr, info_ptr);
+
+ y_offset = png_get_y_offset_inches(png_ptr, info_ptr);
+
+ Each of these returns 0 [signifying "unknown" if both
+ x and y are 0] if the data is not present or if the
+ chunk is present but the unit is the pixel. The
+ remark about inexact inch conversions applies here
+ as well, because a value in inches can't always be
+ converted to microns and back without some loss
+ of precision.
+
+For more information, see the
+PNG specification for chunk contents. Be careful with trusting
+rowbytes, as some of the transformations could increase the space
+needed to hold a row (expand, filler, gray_to_rgb, etc.).
+See png_read_update_info(), below.
+
+A quick word about text_ptr and num_text. PNG stores comments in
+keyword/text pairs, one pair per chunk, with no limit on the number
+of text chunks, and a 2^31 byte limit on their size. While there are
+suggested keywords, there is no requirement to restrict the use to these
+strings. It is strongly suggested that keywords and text be sensible
+to humans (that's the point), so don't use abbreviations. Non-printing
+symbols are not allowed. See the PNG specification for more details.
+There is also no requirement to have text after the keyword.
+
+Keywords should be limited to 79 Latin-1 characters without leading or
+trailing spaces, but non-consecutive spaces are allowed within the
+keyword. It is possible to have the same keyword any number of times.
+The text_ptr is an array of png_text structures, each holding a
+pointer to a language string, a pointer to a keyword and a pointer to
+a text string. The text string, language code, and translated
+keyword may be empty or NULL pointers. The keyword/text
+pairs are put into the array in the order that they are received.
+However, some or all of the text chunks may be after the image, so, to
+make sure you have read all the text chunks, don't mess with these
+until after you read the stuff after the image. This will be
+mentioned again below in the discussion that goes with png_read_end().
+
+.SS Input transformations
+
+After you've read the header information, you can set up the library
+to handle any special transformations of the image data. The various
+ways to transform the data will be described in the order that they
+should occur. This is important, as some of these change the color
+type and/or bit depth of the data, and some others only work on
+certain color types and bit depths.
+
+Transformations you request are ignored if they don't have any meaning for a
+particular input data format. However some transformations can have an effect
+as a result of a previous transformation. If you specify a contradictory set of
+transformations, for example both adding and removing the alpha channel, you
+cannot predict the final result.
+
+The color used for the transparency values should be supplied in the same
+format/depth as the current image data. It is stored in the same format/depth
+as the image data in a tRNS chunk, so this is what libpng expects for this data.
+
+The color used for the background value depends on the need_expand argument as
+described below.
+
+Data will be decoded into the supplied row buffers packed into bytes
+unless the library has been told to transform it into another format.
+For example, 4 bit/pixel paletted or grayscale data will be returned
+2 pixels/byte with the leftmost pixel in the high-order bits of the byte,
+unless png_set_packing() is called. 8-bit RGB data will be stored
+in RGB RGB RGB format unless png_set_filler() or png_set_add_alpha()
+is called to insert filler bytes, either before or after each RGB triplet.
+
+16-bit RGB data will be returned RRGGBB RRGGBB, with the most significant
+byte of the color value first, unless png_set_scale_16() is called to
+transform it to regular RGB RGB triplets, or png_set_filler() or
+png_set_add alpha() is called to insert two filler bytes, either before
+or after each RRGGBB triplet. Similarly, 8-bit or 16-bit grayscale data can
+be modified with png_set_filler(), png_set_add_alpha(), png_set_strip_16(),
+or png_set_scale_16().
+
+The following code transforms grayscale images of less than 8 to 8 bits,
+changes paletted images to RGB, and adds a full alpha channel if there is
+transparency information in a tRNS chunk. This is most useful on
+grayscale images with bit depths of 2 or 4 or if there is a multiple-image
+viewing application that wishes to treat all images in the same way.
+
+ if (color_type == PNG_COLOR_TYPE_PALETTE)
+ png_set_palette_to_rgb(png_ptr);
+
+ if (png_get_valid(png_ptr, info_ptr,
+ PNG_INFO_tRNS)) png_set_tRNS_to_alpha(png_ptr);
+
+ if (color_type == PNG_COLOR_TYPE_GRAY &&
+ bit_depth < 8) png_set_expand_gray_1_2_4_to_8(png_ptr);
+
+The first two functions are actually aliases for png_set_expand(), added
+in libpng version 1.0.4, with the function names expanded to improve code
+readability. In some future version they may actually do different
+things.
+
+As of libpng version 1.2.9, png_set_expand_gray_1_2_4_to_8() was
+added. It expands the sample depth without changing tRNS to alpha.
+
+As of libpng version 1.5.2, png_set_expand_16() was added. It behaves as
+png_set_expand(); however, the resultant channels have 16 bits rather than 8.
+Use this when the output color or gray channels are made linear to avoid fairly
+severe accuracy loss.
+
+ if (bit_depth < 16)
+ png_set_expand_16(png_ptr);
+
+PNG can have files with 16 bits per channel. If you only can handle
+8 bits per channel, this will strip the pixels down to 8-bit.
+
+ if (bit_depth == 16)
+#if PNG_LIBPNG_VER >= 10504
+ png_set_scale_16(png_ptr);
+#else
+ png_set_strip_16(png_ptr);
+#endif
+
+(The more accurate "png_set_scale_16()" API became available in libpng version
+1.5.4).
+
+If you need to process the alpha channel on the image separately from the image
+data (for example if you convert it to a bitmap mask) it is possible to have
+libpng strip the channel leaving just RGB or gray data:
+
+ if (color_type & PNG_COLOR_MASK_ALPHA)
+ png_set_strip_alpha(png_ptr);
+
+If you strip the alpha channel you need to find some other way of dealing with
+the information. If, instead, you want to convert the image to an opaque
+version with no alpha channel use png_set_background; see below.
+
+As of libpng version 1.5.2, almost all useful expansions are supported, the
+major ommissions are conversion of grayscale to indexed images (which can be
+done trivially in the application) and conversion of indexed to grayscale (which
+can be done by a trivial manipulation of the palette.)
+
+In the following table, the 01 means grayscale with depth<8, 31 means
+indexed with depth<8, other numerals represent the color type, "T" means
+the tRNS chunk is present, A means an alpha channel is present, and O
+means tRNS or alpha is present but all pixels in the image are opaque.
+
+ FROM 01 31 0 0T 0O 2 2T 2O 3 3T 3O 4A 4O 6A 6O
+ TO
+ 01 - [G] - - - - - - - - - - - - -
+ 31 [Q] Q [Q] [Q] [Q] Q Q Q Q Q Q [Q] [Q] Q Q
+ 0 1 G + . . G G G G G G B B GB GB
+ 0T lt Gt t + . Gt G G Gt G G Bt Bt GBt GBt
+ 0O lt Gt t . + Gt Gt G Gt Gt G Bt Bt GBt GBt
+ 2 C P C C C + . . C - - CB CB B B
+ 2T Ct - Ct C C t + t - - - CBt CBt Bt Bt
+ 2O Ct - Ct C C t t + - - - CBt CBt Bt Bt
+ 3 [Q] p [Q] [Q] [Q] Q Q Q + . . [Q] [Q] Q Q
+ 3T [Qt] p [Qt][Q] [Q] Qt Qt Qt t + t [Qt][Qt] Qt Qt
+ 3O [Qt] p [Qt][Q] [Q] Qt Qt Qt t t + [Qt][Qt] Qt Qt
+ 4A lA G A T T GA GT GT GA GT GT + BA G GBA
+ 4O lA GBA A T T GA GT GT GA GT GT BA + GBA G
+ 6A CA PA CA C C A T tT PA P P C CBA + BA
+ 6O CA PBA CA C C A tT T PA P P CBA C BA +
+
+Within the matrix,
+ "+" identifies entries where 'from' and 'to' are the same.
+ "-" means the transformation is not supported.
+ "." means nothing is necessary (a tRNS chunk can just be ignored).
+ "t" means the transformation is obtained by png_set_tRNS.
+ "A" means the transformation is obtained by png_set_add_alpha().
+ "X" means the transformation is obtained by png_set_expand().
+ "1" means the transformation is obtained by
+ png_set_expand_gray_1_2_4_to_8() (and by png_set_expand()
+ if there is no transparency in the original or the final
+ format).
+ "C" means the transformation is obtained by png_set_gray_to_rgb().
+ "G" means the transformation is obtained by png_set_rgb_to_gray().
+ "P" means the transformation is obtained by
+ png_set_expand_palette_to_rgb().
+ "p" means the transformation is obtained by png_set_packing().
+ "Q" means the transformation is obtained by png_set_quantize().
+ "T" means the transformation is obtained by
+ png_set_tRNS_to_alpha().
+ "B" means the transformation is obtained by
+ png_set_background(), or png_strip_alpha().
+
+When an entry has multiple transforms listed all are required to cause the
+right overall transformation. When two transforms are separated by a comma
+either will do the job. When transforms are enclosed in [] the transform should
+do the job but this is currently unimplemented - a different format will result
+if the suggested transformations are used.
+
+In PNG files, the alpha channel in an image
+is the level of opacity. If you need the alpha channel in an image to
+be the level of transparency instead of opacity, you can invert the
+alpha channel (or the tRNS chunk data) after it's read, so that 0 is
+fully opaque and 255 (in 8-bit or paletted images) or 65535 (in 16-bit
+images) is fully transparent, with
+
+ png_set_invert_alpha(png_ptr);
+
+PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
+they can, resulting in, for example, 8 pixels per byte for 1 bit
+files. This code expands to 1 pixel per byte without changing the
+values of the pixels:
+
+ if (bit_depth < 8)
+ png_set_packing(png_ptr);
+
+PNG files have possible bit depths of 1, 2, 4, 8, and 16. All pixels
+stored in a PNG image have been "scaled" or "shifted" up to the next
+higher possible bit depth (e.g. from 5 bits/sample in the range [0,31]
+to 8 bits/sample in the range [0, 255]). However, it is also possible
+to convert the PNG pixel data back to the original bit depth of the
+image. This call reduces the pixels back down to the original bit depth:
+
+ png_color_8p sig_bit;
+
+ if (png_get_sBIT(png_ptr, info_ptr, &sig_bit))
+ png_set_shift(png_ptr, sig_bit);
+
+PNG files store 3-color pixels in red, green, blue order. This code
+changes the storage of the pixels to blue, green, red:
+
+ if (color_type == PNG_COLOR_TYPE_RGB ||
+ color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+ png_set_bgr(png_ptr);
+
+PNG files store RGB pixels packed into 3 or 6 bytes. This code expands them
+into 4 or 8 bytes for windowing systems that need them in this format:
+
+ if (color_type == PNG_COLOR_TYPE_RGB)
+ png_set_filler(png_ptr, filler, PNG_FILLER_BEFORE);
+
+where "filler" is the 8-bit or 16-bit number to fill with, and the location
+is either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether
+you want the filler before the RGB or after. When filling an 8-bit pixel,
+the least significant 8 bits of the number are used, if a 16-bit number is
+supplied. This transformation does not affect images that already have full
+alpha channels. To add an opaque alpha channel, use filler=0xffff and
+PNG_FILLER_AFTER which will generate RGBA pixels.
+
+Note that png_set_filler() does not change the color type. If you want
+to do that, you can add a true alpha channel with
+
+ if (color_type == PNG_COLOR_TYPE_RGB ||
+ color_type == PNG_COLOR_TYPE_GRAY)
+ png_set_add_alpha(png_ptr, filler, PNG_FILLER_AFTER);
+
+where "filler" contains the alpha value to assign to each pixel.
+The png_set_add_alpha() function was added in libpng-1.2.7.
+
+If you are reading an image with an alpha channel, and you need the
+data as ARGB instead of the normal PNG format RGBA:
+
+ if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+ png_set_swap_alpha(png_ptr);
+
+For some uses, you may want a grayscale image to be represented as
+RGB. This code will do that conversion:
+
+ if (color_type == PNG_COLOR_TYPE_GRAY ||
+ color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+ png_set_gray_to_rgb(png_ptr);
+
+Conversely, you can convert an RGB or RGBA image to grayscale or grayscale
+with alpha.
+
+ if (color_type == PNG_COLOR_TYPE_RGB ||
+ color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+ png_set_rgb_to_gray(png_ptr, error_action,
+ double red_weight, double green_weight);
+
+ error_action = 1: silently do the conversion
+
+ error_action = 2: issue a warning if the original
+ image has any pixel where
+ red != green or red != blue
+
+ error_action = 3: issue an error and abort the
+ conversion if the original
+ image has any pixel where
+ red != green or red != blue
+
+ red_weight: weight of red component
+
+ green_weight: weight of green component
+ If either weight is negative, default
+ weights are used.
+
+In the corresponding fixed point API the red_weight and green_weight values are
+simply scaled by 100,000:
+
+ png_set_rgb_to_gray(png_ptr, error_action,
+ png_fixed_point red_weight,
+ png_fixed_point green_weight);
+
+If you have set error_action = 1 or 2, you can
+later check whether the image really was gray, after processing
+the image rows, with the png_get_rgb_to_gray_status(png_ptr) function.
+It will return a png_byte that is zero if the image was gray or
+1 if there were any non-gray pixels. Background and sBIT data
+will be silently converted to grayscale, using the green channel
+data for sBIT, regardless of the error_action setting.
+
+The default values come from the PNG file cHRM chunk if present; otherwise, the
+defaults correspond to the ITU-R recommendation 709, and also the sRGB color
+space, as recommended in the Charles Poynton's Colour FAQ,
+Copyright (c) 2006-11-28 Charles Poynton, in section 9:
+
+<http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html#RTFToC9>
+
+ Y = 0.2126 * R + 0.7152 * G + 0.0722 * B
+
+Previous versions of this document, 1998 through 2002, recommended a slightly
+different formula:
+
+ Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
+
+Libpng uses an integer approximation:
+
+ Y = (6968 * R + 23434 * G + 2366 * B)/32768
+
+The calculation is done in a linear colorspace, if the image gamma
+can be determined.
+
+The png_set_background() function has been described already; it tells libpng to
+composite images with alpha or simple transparency against the supplied
+background color. For compatibility with versions of libpng earlier than
+libpng-1.5.4 it is recommended that you call the function after reading the file
+header, even if you don't want to use the color in a bKGD chunk, if one exists.
+
+If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid),
+you may use this color, or supply another color more suitable for
+the current display (e.g., the background color from a web page). You
+need to tell libpng how the color is represented, both the format of the
+component values in the color (the number of bits) and the gamma encoding of the
+color. The function takes two arguments, background_gamma_mode and need_expand
+to convey this information; however, only two combinations are likely to be
+useful:
+
+ png_color_16 my_background;
+ png_color_16p image_background;
+
+ if (png_get_bKGD(png_ptr, info_ptr, &image_background))
+ png_set_background(png_ptr, image_background,
+ PNG_BACKGROUND_GAMMA_FILE, 1/*needs to be expanded*/, 1);
+ else
+ png_set_background(png_ptr, &my_background,
+ PNG_BACKGROUND_GAMMA_SCREEN, 0/*do not expand*/, 1);
+
+The second call was described above - my_background is in the format of the
+final, display, output produced by libpng. Because you now know the format of
+the PNG it is possible to avoid the need to choose either 8-bit or 16-bit
+output and to retain palette images (the palette colors will be modified
+appropriately and the tRNS chunk removed.) However, if you are doing this,
+take great care not to ask for transformations without checking first that
+they apply!
+
+In the first call the background color has the original bit depth and color type
+of the PNG file. So, for palette images the color is supplied as a palette
+index and for low bit greyscale images the color is a reduced bit value in
+image_background->gray.
+
+If you didn't call png_set_gamma() before reading the file header, for example
+if you need your code to remain compatible with older versions of libpng prior
+to libpng-1.5.4, this is the place to call it.
+
+Do not call it if you called png_set_alpha_mode(); doing so will damage the
+settings put in place by png_set_alpha_mode(). (If png_set_alpha_mode() is
+supported then you can certainly do png_set_gamma() before reading the PNG
+header.)
+
+This API unconditionally sets the screen and file gamma values, so it will
+override the value in the PNG file unless it is called before the PNG file
+reading starts. For this reason you must always call it with the PNG file
+value when you call it in this position:
+
+ if (png_get_gAMA(png_ptr, info_ptr, &file_gamma))
+ png_set_gamma(png_ptr, screen_gamma, file_gamma);
+
+ else
+ png_set_gamma(png_ptr, screen_gamma, 0.45455);
+
+If you need to reduce an RGB file to a paletted file, or if a paletted
+file has more entries than will fit on your screen, png_set_quantize()
+will do that. Note that this is a simple match quantization that merely
+finds the closest color available. This should work fairly well with
+optimized palettes, but fairly badly with linear color cubes. If you
+pass a palette that is larger than maximum_colors, the file will
+reduce the number of colors in the palette so it will fit into
+maximum_colors. If there is a histogram, libpng will use it to make
+more intelligent choices when reducing the palette. If there is no
+histogram, it may not do as good a job.
+
+ if (color_type & PNG_COLOR_MASK_COLOR)
+ {
+ if (png_get_valid(png_ptr, info_ptr,
+ PNG_INFO_PLTE))
+ {
+ png_uint_16p histogram = NULL;
+
+ png_get_hIST(png_ptr, info_ptr,
+ &histogram);
+ png_set_quantize(png_ptr, palette, num_palette,
+ max_screen_colors, histogram, 1);
+ }
+
+ else
+ {
+ png_color std_color_cube[MAX_SCREEN_COLORS] =
+ { ... colors ... };
+
+ png_set_quantize(png_ptr, std_color_cube,
+ MAX_SCREEN_COLORS, MAX_SCREEN_COLORS,
+ NULL,0);
+ }
+ }
+
+PNG files describe monochrome as black being zero and white being one.
+The following code will reverse this (make black be one and white be
+zero):
+
+ if (bit_depth == 1 && color_type == PNG_COLOR_TYPE_GRAY)
+ png_set_invert_mono(png_ptr);
+
+This function can also be used to invert grayscale and gray-alpha images:
+
+ if (color_type == PNG_COLOR_TYPE_GRAY ||
+ color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+ png_set_invert_mono(png_ptr);
+
+PNG files store 16-bit pixels in network byte order (big-endian,
+ie. most significant bits first). This code changes the storage to the
+other way (little-endian, i.e. least significant bits first, the
+way PCs store them):
+
+ if (bit_depth == 16)
+ png_set_swap(png_ptr);
+
+If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
+need to change the order the pixels are packed into bytes, you can use:
+
+ if (bit_depth < 8)
+ png_set_packswap(png_ptr);
+
+Finally, you can write your own transformation function if none of
+the existing ones meets your needs. This is done by setting a callback
+with
+
+ png_set_read_user_transform_fn(png_ptr,
+ read_transform_fn);
+
+You must supply the function
+
+ void read_transform_fn(png_structp png_ptr, png_row_infop
+ row_info, png_bytep data)
+
+See pngtest.c for a working example. Your function will be called
+after all of the other transformations have been processed. Take care with
+interlaced images if you do the interlace yourself - the width of the row is the
+width in 'row_info', not the overall image width.
+
+If supported, libpng provides two information routines that you can use to find
+where you are in processing the image:
+
+ png_get_current_pass_number(png_structp png_ptr);
+ png_get_current_row_number(png_structp png_ptr);
+
+Don't try using these outside a transform callback - firstly they are only
+supported if user transforms are supported, secondly they may well return
+unexpected results unless the row is actually being processed at the moment they
+are called.
+
+With interlaced
+images the value returned is the row in the input sub-image image. Use
+PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
+find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass).
+
+The discussion of interlace handling above contains more information on how to
+use these values.
+
+You can also set up a pointer to a user structure for use by your
+callback function, and you can inform libpng that your transform
+function will change the number of channels or bit depth with the
+function
+
+ png_set_user_transform_info(png_ptr, user_ptr,
+ user_depth, user_channels);
+
+The user's application, not libpng, is responsible for allocating and
+freeing any memory required for the user structure.
+
+You can retrieve the pointer via the function
+png_get_user_transform_ptr(). For example:
+
+ voidp read_user_transform_ptr =
+ png_get_user_transform_ptr(png_ptr);
+
+The last thing to handle is interlacing; this is covered in detail below,
+but you must call the function here if you want libpng to handle expansion
+of the interlaced image.
+
+ number_of_passes = png_set_interlace_handling(png_ptr);
+
+After setting the transformations, libpng can update your png_info
+structure to reflect any transformations you've requested with this
+call.
+
+ png_read_update_info(png_ptr, info_ptr);
+
+This is most useful to update the info structure's rowbytes
+field so you can use it to allocate your image memory. This function
+will also update your palette with the correct screen_gamma and
+background if these have been given with the calls above. You may
+only call png_read_update_info() once with a particular info_ptr.
+
+After you call png_read_update_info(), you can allocate any
+memory you need to hold the image. The row data is simply
+raw byte data for all forms of images. As the actual allocation
+varies among applications, no example will be given. If you
+are allocating one large chunk, you will need to build an
+array of pointers to each row, as it will be needed for some
+of the functions below.
+
+Remember: Before you call png_read_update_info(), the png_get_*()
+functions return the values corresponding to the original PNG image.
+After you call png_read_update_info the values refer to the image
+that libpng will output. Consequently you must call all the png_set_
+functions before you call png_read_update_info(). This is particularly
+important for png_set_interlace_handling() - if you are going to call
+png_read_update_info() you must call png_set_interlace_handling() before
+it unless you want to receive interlaced output.
+
+.SS Reading image data
+
+After you've allocated memory, you can read the image data.
+The simplest way to do this is in one function call. If you are
+allocating enough memory to hold the whole image, you can just
+call png_read_image() and libpng will read in all the image data
+and put it in the memory area supplied. You will need to pass in
+an array of pointers to each row.
+
+This function automatically handles interlacing, so you don't
+need to call png_set_interlace_handling() (unless you call
+png_read_update_info()) or call this function multiple times, or any
+of that other stuff necessary with png_read_rows().
+
+ png_read_image(png_ptr, row_pointers);
+
+where row_pointers is:
+
+ png_bytep row_pointers[height];
+
+You can point to void or char or whatever you use for pixels.
+
+If you don't want to read in the whole image at once, you can
+use png_read_rows() instead. If there is no interlacing (check
+interlace_type == PNG_INTERLACE_NONE), this is simple:
+
+ png_read_rows(png_ptr, row_pointers, NULL,
+ number_of_rows);
+
+where row_pointers is the same as in the png_read_image() call.
+
+If you are doing this just one row at a time, you can do this with
+a single row_pointer instead of an array of row_pointers:
+
+ png_bytep row_pointer = row;
+ png_read_row(png_ptr, row_pointer, NULL);
+
+If the file is interlaced (interlace_type != 0 in the IHDR chunk), things
+get somewhat harder. The only current (PNG Specification version 1.2)
+interlacing type for PNG is (interlace_type == PNG_INTERLACE_ADAM7);
+a somewhat complicated 2D interlace scheme, known as Adam7, that
+breaks down an image into seven smaller images of varying size, based
+on an 8x8 grid. This number is defined (from libpng 1.5) as
+PNG_INTERLACE_ADAM7_PASSES in png.h
+
+libpng can fill out those images or it can give them to you "as is".
+It is almost always better to have libpng handle the interlacing for you.
+If you want the images filled out, there are two ways to do that. The one
+mentioned in the PNG specification is to expand each pixel to cover
+those pixels that have not been read yet (the "rectangle" method).
+This results in a blocky image for the first pass, which gradually
+smooths out as more pixels are read. The other method is the "sparkle"
+method, where pixels are drawn only in their final locations, with the
+rest of the image remaining whatever colors they were initialized to
+before the start of the read. The first method usually looks better,
+but tends to be slower, as there are more pixels to put in the rows.
+
+If, as is likely, you want libpng to expand the images, call this before
+calling png_start_read_image() or png_read_update_info():
+
+ if (interlace_type == PNG_INTERLACE_ADAM7)
+ number_of_passes
+ = png_set_interlace_handling(png_ptr);
+
+This will return the number of passes needed. Currently, this is seven,
+but may change if another interlace type is added. This function can be
+called even if the file is not interlaced, where it will return one pass.
+You then need to read the whole image 'number_of_passes' times. Each time
+will distribute the pixels from the current pass to the correct place in
+the output image, so you need to supply the same rows to png_read_rows in
+each pass.
+
+If you are not going to display the image after each pass, but are
+going to wait until the entire image is read in, use the sparkle
+effect. This effect is faster and the end result of either method
+is exactly the same. If you are planning on displaying the image
+after each pass, the "rectangle" effect is generally considered the
+better looking one.
+
+If you only want the "sparkle" effect, just call png_read_rows() as
+normal, with the third parameter NULL. Make sure you make pass over
+the image number_of_passes times, and you don't change the data in the
+rows between calls. You can change the locations of the data, just
+not the data. Each pass only writes the pixels appropriate for that
+pass, and assumes the data from previous passes is still valid.
+
+ png_read_rows(png_ptr, row_pointers, NULL,
+ number_of_rows);
+
+If you only want the first effect (the rectangles), do the same as
+before except pass the row buffer in the third parameter, and leave
+the second parameter NULL.
+
+ png_read_rows(png_ptr, NULL, row_pointers,
+ number_of_rows);
+
+If you don't want libpng to handle the interlacing details, just call
+png_read_rows() PNG_INTERLACE_ADAM7_PASSES times to read in all the images.
+Each of the images is a valid image by itself; however, you will almost
+certainly need to distribute the pixels from each sub-image to the
+correct place. This is where everything gets very tricky.
+
+If you want to retrieve the separate images you must pass the correct
+number of rows to each successive call of png_read_rows(). The calculation
+gets pretty complicated for small images, where some sub-images may
+not even exist because either their width or height ends up zero.
+libpng provides two macros to help you in 1.5 and later versions:
+
+ png_uint_32 width = PNG_PASS_COLS(image_width, pass_number);
+ png_uint_32 height = PNG_PASS_ROWS(image_height, pass_number);
+
+Respectively these tell you the width and height of the sub-image
+corresponding to the numbered pass. 'pass' is in in the range 0 to 6 -
+this can be confusing because the specification refers to the same passes
+as 1 to 7! Be careful, you must check both the width and height before
+calling png_read_rows() and not call it for that pass if either is zero.
+
+You can, of course, read each sub-image row by row. If you want to
+produce optimal code to make a pixel-by-pixel transformation of an
+interlaced image this is the best approach; read each row of each pass,
+transform it, and write it out to a new interlaced image.
+
+If you want to de-interlace the image yourself libpng provides further
+macros to help that tell you where to place the pixels in the output image.
+Because the interlacing scheme is rectangular - sub-image pixels are always
+arranged on a rectangular grid - all you need to know for each pass is the
+starting column and row in the output image of the first pixel plus the
+spacing between each pixel. As of libpng 1.5 there are four macros to
+retrieve this information:
+
+ png_uint_32 x = PNG_PASS_START_COL(pass);
+ png_uint_32 y = PNG_PASS_START_ROW(pass);
+ png_uint_32 xStep = 1U << PNG_PASS_COL_SHIFT(pass);
+ png_uint_32 yStep = 1U << PNG_PASS_ROW_SHIFT(pass);
+
+These allow you to write the obvious loop:
+
+ png_uint_32 input_y = 0;
+ png_uint_32 output_y = PNG_PASS_START_ROW(pass);
+
+ while (output_y < output_image_height)
+ {
+ png_uint_32 input_x = 0;
+ png_uint_32 output_x = PNG_PASS_START_COL(pass);
+
+ while (output_x < output_image_width)
+ {
+ image[output_y][output_x] =
+ subimage[pass][input_y][input_x++];
+
+ output_x += xStep;
+ }
+
+ ++input_y;
+ output_y += yStep;
+ }
+
+Notice that the steps between successive output rows and columns are
+returned as shifts. This is possible because the pixels in the subimages
+are always a power of 2 apart - 1, 2, 4 or 8 pixels - in the original
+image. In practice you may need to directly calculate the output coordinate
+given an input coordinate. libpng provides two further macros for this
+purpose:
+
+ png_uint_32 output_x = PNG_COL_FROM_PASS_COL(input_x, pass);
+ png_uint_32 output_y = PNG_ROW_FROM_PASS_ROW(input_y, pass);
+
+Finally a pair of macros are provided to tell you if a particular image
+row or column appears in a given pass:
+
+ int col_in_pass = PNG_COL_IN_INTERLACE_PASS(output_x, pass);
+ int row_in_pass = PNG_ROW_IN_INTERLACE_PASS(output_y, pass);
+
+Bear in mind that you will probably also need to check the width and height
+of the pass in addition to the above to be sure the pass even exists!
+
+With any luck you are convinced by now that you don't want to do your own
+interlace handling. In reality normally the only good reason for doing this
+is if you are processing PNG files on a pixel-by-pixel basis and don't want
+to load the whole file into memory when it is interlaced.
+
+libpng includes a test program, pngvalid, that illustrates reading and
+writing of interlaced images. If you can't get interlacing to work in your
+code and don't want to leave it to libpng (the recommended approach), see
+how pngvalid.c does it.
+
+.SS Finishing a sequential read
+
+After you are finished reading the image through the
+low-level interface, you can finish reading the file.
+
+If you want to use a different crc action for handling CRC errors in
+chunks after the image data, you can call png_set_crc_action()
+again at this point.
+
+If you are interested in comments or time, which may be stored either
+before or after the image data, you should pass the separate png_info
+struct if you want to keep the comments from before and after the image
+separate.
+
+ png_infop end_info = png_create_info_struct(png_ptr);
+
+ if (!end_info)
+ {
+ png_destroy_read_struct(&png_ptr, &info_ptr,
+ (png_infopp)NULL);
+ return (ERROR);
+ }
+
+ png_read_end(png_ptr, end_info);
+
+If you are not interested, you should still call png_read_end()
+but you can pass NULL, avoiding the need to create an end_info structure.
+If you do this, libpng will not process any chunks after IDAT other than
+skipping over them and perhaps (depending on whether you have called
+png_set_crc_action) checking their CRCs while looking for the IEND chunk.
+
+ png_read_end(png_ptr, (png_infop)NULL);
+
+If you don't call png_read_end(), then your file pointer will be
+left pointing to the first chunk after the last IDAT, which is probably
+not what you want if you expect to read something beyond the end of
+the PNG datastream.
+
+When you are done, you can free all memory allocated by libpng like this:
+
+ png_destroy_read_struct(&png_ptr, &info_ptr,
+ &end_info);
+
+or, if you didn't create an end_info structure,
+
+ png_destroy_read_struct(&png_ptr, &info_ptr,
+ (png_infopp)NULL);
+
+It is also possible to individually free the info_ptr members that
+point to libpng-allocated storage with the following function:
+
+ png_free_data(png_ptr, info_ptr, mask, seq)
+
+ mask - identifies data to be freed, a mask
+ containing the bitwise OR of one or
+ more of
+ PNG_FREE_PLTE, PNG_FREE_TRNS,
+ PNG_FREE_HIST, PNG_FREE_ICCP,
+ PNG_FREE_PCAL, PNG_FREE_ROWS,
+ PNG_FREE_SCAL, PNG_FREE_SPLT,
+ PNG_FREE_TEXT, PNG_FREE_UNKN,
+ or simply PNG_FREE_ALL
+
+ seq - sequence number of item to be freed
+ (\-1 for all items)
+
+This function may be safely called when the relevant storage has
+already been freed, or has not yet been allocated, or was allocated
+by the user and not by libpng, and will in those cases do nothing.
+The "seq" parameter is ignored if only one item of the selected data
+type, such as PLTE, is allowed. If "seq" is not \-1, and multiple items
+are allowed for the data type identified in the mask, such as text or
+sPLT, only the n'th item in the structure is freed, where n is "seq".
+
+The default behavior is only to free data that was allocated internally
+by libpng. This can be changed, so that libpng will not free the data,
+or so that it will free data that was allocated by the user with png_malloc()
+or png_calloc() and passed in via a png_set_*() function, with
+
+ png_data_freer(png_ptr, info_ptr, freer, mask)
+
+ freer - one of
+ PNG_DESTROY_WILL_FREE_DATA
+ PNG_SET_WILL_FREE_DATA
+ PNG_USER_WILL_FREE_DATA
+
+ mask - which data elements are affected
+ same choices as in png_free_data()
+
+This function only affects data that has already been allocated.
+You can call this function after reading the PNG data but before calling
+any png_set_*() functions, to control whether the user or the png_set_*()
+function is responsible for freeing any existing data that might be present,
+and again after the png_set_*() functions to control whether the user
+or png_destroy_*() is supposed to free the data. When the user assumes
+responsibility for libpng-allocated data, the application must use
+png_free() to free it, and when the user transfers responsibility to libpng
+for data that the user has allocated, the user must have used png_malloc()
+or png_calloc() to allocate it.
+
+If you allocated your row_pointers in a single block, as suggested above in
+the description of the high level read interface, you must not transfer
+responsibility for freeing it to the png_set_rows or png_read_destroy function,
+because they would also try to free the individual row_pointers[i].
+
+If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
+separately, do not transfer responsibility for freeing text_ptr to libpng,
+because when libpng fills a png_text structure it combines these members with
+the key member, and png_free_data() will free only text_ptr.key. Similarly,
+if you transfer responsibility for free'ing text_ptr from libpng to your
+application, your application must not separately free those members.
+
+The png_free_data() function will turn off the "valid" flag for anything
+it frees. If you need to turn the flag off for a chunk that was freed by
+your application instead of by libpng, you can use
+
+ png_set_invalid(png_ptr, info_ptr, mask);
+
+ mask - identifies the chunks to be made invalid,
+ containing the bitwise OR of one or
+ more of
+ PNG_INFO_gAMA, PNG_INFO_sBIT,
+ PNG_INFO_cHRM, PNG_INFO_PLTE,
+ PNG_INFO_tRNS, PNG_INFO_bKGD,
+ PNG_INFO_hIST, PNG_INFO_pHYs,
+ PNG_INFO_oFFs, PNG_INFO_tIME,
+ PNG_INFO_pCAL, PNG_INFO_sRGB,
+ PNG_INFO_iCCP, PNG_INFO_sPLT,
+ PNG_INFO_sCAL, PNG_INFO_IDAT
+
+For a more compact example of reading a PNG image, see the file example.c.
+
+.SS Reading PNG files progressively
+
+The progressive reader is slightly different from the non-progressive
+reader. Instead of calling png_read_info(), png_read_rows(), and
+png_read_end(), you make one call to png_process_data(), which calls
+callbacks when it has the info, a row, or the end of the image. You
+set up these callbacks with png_set_progressive_read_fn(). You don't
+have to worry about the input/output functions of libpng, as you are
+giving the library the data directly in png_process_data(). I will
+assume that you have read the section on reading PNG files above,
+so I will only highlight the differences (although I will show
+all of the code).
+
+png_structp png_ptr;
+png_infop info_ptr;
+
+ /* An example code fragment of how you would
+ initialize the progressive reader in your
+ application. */
+ int
+ initialize_png_reader()
+ {
+ png_ptr = png_create_read_struct
+ (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+ user_error_fn, user_warning_fn);
+
+ if (!png_ptr)
+ return (ERROR);
+
+ info_ptr = png_create_info_struct(png_ptr);
+
+ if (!info_ptr)
+ {
+ png_destroy_read_struct(&png_ptr,
+ (png_infopp)NULL, (png_infopp)NULL);
+ return (ERROR);
+ }
+
+ if (setjmp(png_jmpbuf(png_ptr)))
+ {
+ png_destroy_read_struct(&png_ptr, &info_ptr,
+ (png_infopp)NULL);
+ return (ERROR);
+ }
+
+ /* This one's new. You can provide functions
+ to be called when the header info is valid,
+ when each row is completed, and when the image
+ is finished. If you aren't using all functions,
+ you can specify NULL parameters. Even when all
+ three functions are NULL, you need to call
+ png_set_progressive_read_fn(). You can use
+ any struct as the user_ptr (cast to a void pointer
+ for the function call), and retrieve the pointer
+ from inside the callbacks using the function
+
+ png_get_progressive_ptr(png_ptr);
+
+ which will return a void pointer, which you have
+ to cast appropriately.
+ */
+ png_set_progressive_read_fn(png_ptr, (void *)user_ptr,
+ info_callback, row_callback, end_callback);
+
+ return 0;
+ }
+
+ /* A code fragment that you call as you receive blocks
+ of data */
+ int
+ process_data(png_bytep buffer, png_uint_32 length)
+ {
+ if (setjmp(png_jmpbuf(png_ptr)))
+ {
+ png_destroy_read_struct(&png_ptr, &info_ptr,
+ (png_infopp)NULL);
+ return (ERROR);
+ }
+
+ /* This one's new also. Simply give it a chunk
+ of data from the file stream (in order, of
+ course). On machines with segmented memory
+ models machines, don't give it any more than
+ 64K. The library seems to run fine with sizes
+ of 4K. Although you can give it much less if
+ necessary (I assume you can give it chunks of
+ 1 byte, I haven't tried less than 256 bytes
+ yet). When this function returns, you may
+ want to display any rows that were generated
+ in the row callback if you don't already do
+ so there.
+ */
+ png_process_data(png_ptr, info_ptr, buffer, length);
+
+ /* At this point you can call png_process_data_skip if
+ you want to handle data the library will skip yourself;
+ it simply returns the number of bytes to skip (and stops
+ libpng skipping that number of bytes on the next
+ png_process_data call).
+ return 0;
+ }
+
+ /* This function is called (as set by
+ png_set_progressive_read_fn() above) when enough data
+ has been supplied so all of the header has been
+ read.
+ */
+ void
+ info_callback(png_structp png_ptr, png_infop info)
+ {
+ /* Do any setup here, including setting any of
+ the transformations mentioned in the Reading
+ PNG files section. For now, you _must_ call
+ either png_start_read_image() or
+ png_read_update_info() after all the
+ transformations are set (even if you don't set
+ any). You may start getting rows before
+ png_process_data() returns, so this is your
+ last chance to prepare for that.
+
+ This is where you turn on interlace handling,
+ assuming you don't want to do it yourself.
+
+ If you need to you can stop the processing of
+ your original input data at this point by calling
+ png_process_data_pause. This returns the number
+ of unprocessed bytes from the last png_process_data
+ call - it is up to you to ensure that the next call
+ sees these bytes again. If you don't want to bother
+ with this you can get libpng to cache the unread
+ bytes by setting the 'save' parameter (see png.h) but
+ then libpng will have to copy the data internally.
+ */
+ }
+
+ /* This function is called when each row of image
+ data is complete */
+ void
+ row_callback(png_structp png_ptr, png_bytep new_row,
+ png_uint_32 row_num, int pass)
+ {
+ /* If the image is interlaced, and you turned
+ on the interlace handler, this function will
+ be called for every row in every pass. Some
+ of these rows will not be changed from the
+ previous pass. When the row is not changed,
+ the new_row variable will be NULL. The rows
+ and passes are called in order, so you don't
+ really need the row_num and pass, but I'm
+ supplying them because it may make your life
+ easier.
+
+ If you did not turn on interlace handling then
+ the callback is called for each row of each
+ sub-image when the image is interlaced. In this
+ case 'row_num' is the row in the sub-image, not
+ the row in the output image as it is in all other
+ cases.
+
+ For the non-NULL rows of interlaced images when
+ you have switched on libpng interlace handling,
+ you must call png_progressive_combine_row()
+ passing in the row and the old row. You can
+ call this function for NULL rows (it will just
+ return) and for non-interlaced images (it just
+ does the memcpy for you) if it will make the
+ code easier. Thus, you can just do this for
+ all cases if you switch on interlace handling;
+ */
+
+ png_progressive_combine_row(png_ptr, old_row,
+ new_row);
+
+ /* where old_row is what was displayed
+ previously for the row. Note that the first
+ pass (pass == 0, really) will completely cover
+ the old row, so the rows do not have to be
+ initialized. After the first pass (and only
+ for interlaced images), you will have to pass
+ the current row, and the function will combine
+ the old row and the new row.
+
+ You can also call png_process_data_pause in this
+ callback - see above.
+ */
+ }
+
+ void
+ end_callback(png_structp png_ptr, png_infop info)
+ {
+ /* This function is called after the whole image
+ has been read, including any chunks after the
+ image (up to and including the IEND). You
+ will usually have the same info chunk as you
+ had in the header, although some data may have
+ been added to the comments and time fields.
+
+ Most people won't do much here, perhaps setting
+ a flag that marks the image as finished.
+ */
+ }
+
+
+
+.SH IV. Writing
+
+Much of this is very similar to reading. However, everything of
+importance is repeated here, so you won't have to constantly look
+back up in the reading section to understand writing.
+
+.SS Setup
+
+You will want to do the I/O initialization before you get into libpng,
+so if it doesn't work, you don't have anything to undo. If you are not
+using the standard I/O functions, you will need to replace them with
+custom writing functions. See the discussion under Customizing libpng.
+
+ FILE *fp = fopen(file_name, "wb");
+
+ if (!fp)
+ return (ERROR);
+
+Next, png_struct and png_info need to be allocated and initialized.
+As these can be both relatively large, you may not want to store these
+on the stack, unless you have stack space to spare. Of course, you
+will want to check if they return NULL. If you are also reading,
+you won't want to name your read structure and your write structure
+both "png_ptr"; you can call them anything you like, such as
+"read_ptr" and "write_ptr". Look at pngtest.c, for example.
+
+ png_structp png_ptr = png_create_write_struct
+ (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+ user_error_fn, user_warning_fn);
+
+ if (!png_ptr)
+ return (ERROR);
+
+ png_infop info_ptr = png_create_info_struct(png_ptr);
+ if (!info_ptr)
+ {
+ png_destroy_write_struct(&png_ptr,
+ (png_infopp)NULL);
+ return (ERROR);
+ }
+
+If you want to use your own memory allocation routines,
+define PNG_USER_MEM_SUPPORTED and use
+png_create_write_struct_2() instead of png_create_write_struct():
+
+ png_structp png_ptr = png_create_write_struct_2
+ (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
+ user_error_fn, user_warning_fn, (png_voidp)
+ user_mem_ptr, user_malloc_fn, user_free_fn);
+
+After you have these structures, you will need to set up the
+error handling. When libpng encounters an error, it expects to
+longjmp() back to your routine. Therefore, you will need to call
+setjmp() and pass the png_jmpbuf(png_ptr). If you
+write the file from different routines, you will need to update
+the png_jmpbuf(png_ptr) every time you enter a new routine that will
+call a png_*() function. See your documentation of setjmp/longjmp
+for your compiler for more information on setjmp/longjmp. See
+the discussion on libpng error handling in the Customizing Libpng
+section below for more information on the libpng error handling.
+
+ if (setjmp(png_jmpbuf(png_ptr)))
+ {
+ png_destroy_write_struct(&png_ptr, &info_ptr);
+ fclose(fp);
+ return (ERROR);
+ }
+ ...
+ return;
+
+If you would rather avoid the complexity of setjmp/longjmp issues,
+you can compile libpng with PNG_NO_SETJMP, in which case
+errors will result in a call to PNG_ABORT() which defaults to abort().
+
+You can #define PNG_ABORT() to a function that does something
+more useful than abort(), as long as your function does not
+return.
+
+Checking for invalid palette index on write was added at libpng
+1.5.10. If a pixel contains an invalid (out-of-range) index libpng issues
+a benign error. This is enabled by default because this condition is an
+error according to the PNG specification, Clause 11.3.2, but the error can
+be ignored in each png_ptr with
+
+ png_set_check_for_invalid_index(png_ptr, 0);
+
+If the error is ignored, or if png_benign_error() treats it as a warning,
+any invalid pixels are written as-is by the encoder, resulting in an
+invalid PNG datastream as output. In this case the application is
+responsible for ensuring that the pixel indexes are in range when it writes
+a PLTE chunk with fewer entries than the bit depth would allow.
+
+Now you need to set up the output code. The default for libpng is to
+use the C function fwrite(). If you use this, you will need to pass a
+valid FILE * in the function png_init_io(). Be sure that the file is
+opened in binary mode. Again, if you wish to handle writing data in
+another way, see the discussion on libpng I/O handling in the Customizing
+Libpng section below.
+
+ png_init_io(png_ptr, fp);
+
+If you are embedding your PNG into a datastream such as MNG, and don't
+want libpng to write the 8-byte signature, or if you have already
+written the signature in your application, use
+
+ png_set_sig_bytes(png_ptr, 8);
+
+to inform libpng that it should not write a signature.
+
+.SS Write callbacks
+
+At this point, you can set up a callback function that will be
+called after each row has been written, which you can use to control
+a progress meter or the like. It's demonstrated in pngtest.c.
+You must supply a function
+
+ void write_row_callback(png_structp png_ptr, png_uint_32 row,
+ int pass);
+ {
+ /* put your code here */
+ }
+
+(You can give it another name that you like instead of "write_row_callback")
+
+To inform libpng about your function, use
+
+ png_set_write_status_fn(png_ptr, write_row_callback);
+
+When this function is called the row has already been completely processed and
+it has also been written out. The 'row' and 'pass' refer to the next row to be
+handled. For the
+non-interlaced case the row that was just handled is simply one less than the
+passed in row number, and pass will always be 0. For the interlaced case the
+same applies unless the row value is 0, in which case the row just handled was
+the last one from one of the preceding passes. Because interlacing may skip a
+pass you cannot be sure that the preceding pass is just 'pass\-1', if you really
+need to know what the last pass is record (row,pass) from the callback and use
+the last recorded value each time.
+
+As with the user transform you can find the output row using the
+PNG_ROW_FROM_PASS_ROW macro.
+
+You now have the option of modifying how the compression library will
+run. The following functions are mainly for testing, but may be useful
+in some cases, like if you need to write PNG files extremely fast and
+are willing to give up some compression, or if you want to get the
+maximum possible compression at the expense of slower writing. If you
+have no special needs in this area, let the library do what it wants by
+not calling this function at all, as it has been tuned to deliver a good
+speed/compression ratio. The second parameter to png_set_filter() is
+the filter method, for which the only valid values are 0 (as of the
+July 1999 PNG specification, version 1.2) or 64 (if you are writing
+a PNG datastream that is to be embedded in a MNG datastream). The third
+parameter is a flag that indicates which filter type(s) are to be tested
+for each scanline. See the PNG specification for details on the specific
+filter types.
+
+
+ /* turn on or off filtering, and/or choose
+ specific filters. You can use either a single
+ PNG_FILTER_VALUE_NAME or the bitwise OR of one
+ or more PNG_FILTER_NAME masks.
+ */
+ png_set_filter(png_ptr, 0,
+ PNG_FILTER_NONE | PNG_FILTER_VALUE_NONE |
+ PNG_FILTER_SUB | PNG_FILTER_VALUE_SUB |
+ PNG_FILTER_UP | PNG_FILTER_VALUE_UP |
+ PNG_FILTER_AVG | PNG_FILTER_VALUE_AVG |
+ PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH|
+ PNG_ALL_FILTERS);
+
+If an application wants to start and stop using particular filters during
+compression, it should start out with all of the filters (to ensure that
+the previous row of pixels will be stored in case it's needed later),
+and then add and remove them after the start of compression.
+
+If you are writing a PNG datastream that is to be embedded in a MNG
+datastream, the second parameter can be either 0 or 64.
+
+The png_set_compression_*() functions interface to the zlib compression
+library, and should mostly be ignored unless you really know what you are
+doing. The only generally useful call is png_set_compression_level()
+which changes how much time zlib spends on trying to compress the image
+data. See the Compression Library (zlib.h and algorithm.txt, distributed
+with zlib) for details on the compression levels.
+
+ #include zlib.h
+
+ /* Set the zlib compression level */
+ png_set_compression_level(png_ptr,
+ Z_BEST_COMPRESSION);
+
+ /* Set other zlib parameters for compressing IDAT */
+ png_set_compression_mem_level(png_ptr, 8);
+ png_set_compression_strategy(png_ptr,
+ Z_DEFAULT_STRATEGY);
+ png_set_compression_window_bits(png_ptr, 15);
+ png_set_compression_method(png_ptr, 8);
+ png_set_compression_buffer_size(png_ptr, 8192)
+
+ /* Set zlib parameters for text compression
+ * If you don't call these, the parameters
+ * fall back on those defined for IDAT chunks
+ */
+ png_set_text_compression_mem_level(png_ptr, 8);
+ png_set_text_compression_strategy(png_ptr,
+ Z_DEFAULT_STRATEGY);
+ png_set_text_compression_window_bits(png_ptr, 15);
+ png_set_text_compression_method(png_ptr, 8);
+
+.SS Setting the contents of info for output
+
+You now need to fill in the png_info structure with all the data you
+wish to write before the actual image. Note that the only thing you
+are allowed to write after the image is the text chunks and the time
+chunk (as of PNG Specification 1.2, anyway). See png_write_end() and
+the latest PNG specification for more information on that. If you
+wish to write them before the image, fill them in now, and flag that
+data as being valid. If you want to wait until after the data, don't
+fill them until png_write_end(). For all the fields in png_info and
+their data types, see png.h. For explanations of what the fields
+contain, see the PNG specification.
+
+Some of the more important parts of the png_info are:
+
+ png_set_IHDR(png_ptr, info_ptr, width, height,
+ bit_depth, color_type, interlace_type,
+ compression_type, filter_method)
+
+ width - holds the width of the image
+ in pixels (up to 2^31).
+
+ height - holds the height of the image
+ in pixels (up to 2^31).
+
+ bit_depth - holds the bit depth of one of the
+ image channels.
+ (valid values are 1, 2, 4, 8, 16
+ and depend also on the
+ color_type. See also significant
+ bits (sBIT) below).
+
+ color_type - describes which color/alpha
+ channels are present.
+ PNG_COLOR_TYPE_GRAY
+ (bit depths 1, 2, 4, 8, 16)
+ PNG_COLOR_TYPE_GRAY_ALPHA
+ (bit depths 8, 16)
+ PNG_COLOR_TYPE_PALETTE
+ (bit depths 1, 2, 4, 8)
+ PNG_COLOR_TYPE_RGB
+ (bit_depths 8, 16)
+ PNG_COLOR_TYPE_RGB_ALPHA
+ (bit_depths 8, 16)
+
+ PNG_COLOR_MASK_PALETTE
+ PNG_COLOR_MASK_COLOR
+ PNG_COLOR_MASK_ALPHA
+
+ interlace_type - PNG_INTERLACE_NONE or
+ PNG_INTERLACE_ADAM7
+
+ compression_type - (must be
+ PNG_COMPRESSION_TYPE_DEFAULT)
+
+ filter_method - (must be PNG_FILTER_TYPE_DEFAULT
+ or, if you are writing a PNG to
+ be embedded in a MNG datastream,
+ can also be
+ PNG_INTRAPIXEL_DIFFERENCING)
+
+If you call png_set_IHDR(), the call must appear before any of the
+other png_set_*() functions, because they might require access to some of
+the IHDR settings. The remaining png_set_*() functions can be called
+in any order.
+
+If you wish, you can reset the compression_type, interlace_type, or
+filter_method later by calling png_set_IHDR() again; if you do this, the
+width, height, bit_depth, and color_type must be the same in each call.
+
+ png_set_PLTE(png_ptr, info_ptr, palette,
+ num_palette);
+
+ palette - the palette for the file
+ (array of png_color)
+ num_palette - number of entries in the palette
+
+
+ png_set_gAMA(png_ptr, info_ptr, file_gamma);
+ png_set_gAMA_fixed(png_ptr, info_ptr, int_file_gamma);
+
+ file_gamma - the gamma at which the image was
+ created (PNG_INFO_gAMA)
+
+ int_file_gamma - 100,000 times the gamma at which
+ the image was created
+
+ png_set_cHRM(png_ptr, info_ptr, white_x, white_y, red_x, red_y,
+ green_x, green_y, blue_x, blue_y)
+ png_set_cHRM_XYZ(png_ptr, info_ptr, red_X, red_Y, red_Z, green_X,
+ green_Y, green_Z, blue_X, blue_Y, blue_Z)
+ png_set_cHRM_fixed(png_ptr, info_ptr, int_white_x, int_white_y,
+ int_red_x, int_red_y, int_green_x, int_green_y,
+ int_blue_x, int_blue_y)
+ png_set_cHRM_XYZ_fixed(png_ptr, info_ptr, int_red_X, int_red_Y,
+ int_red_Z, int_green_X, int_green_Y, int_green_Z,
+ int_blue_X, int_blue_Y, int_blue_Z)
+
+ {white,red,green,blue}_{x,y}
+ A color space encoding specified using the chromaticities
+ of the end points and the white point.
+
+ {red,green,blue}_{X,Y,Z}
+ A color space encoding specified using the encoding end
+ points - the CIE tristimulus specification of the intended
+ color of the red, green and blue channels in the PNG RGB
+ data. The white point is simply the sum of the three end
+ points.
+
+ png_set_sRGB(png_ptr, info_ptr, srgb_intent);
+
+ srgb_intent - the rendering intent
+ (PNG_INFO_sRGB) The presence of
+ the sRGB chunk means that the pixel
+ data is in the sRGB color space.
+ This chunk also implies specific
+ values of gAMA and cHRM. Rendering
+ intent is the CSS-1 property that
+ has been defined by the International
+ Color Consortium
+ (http://www.color.org).
+ It can be one of
+ PNG_sRGB_INTENT_SATURATION,
+ PNG_sRGB_INTENT_PERCEPTUAL,
+ PNG_sRGB_INTENT_ABSOLUTE, or
+ PNG_sRGB_INTENT_RELATIVE.
+
+
+ png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr,
+ srgb_intent);
+
+ srgb_intent - the rendering intent
+ (PNG_INFO_sRGB) The presence of the
+ sRGB chunk means that the pixel
+ data is in the sRGB color space.
+ This function also causes gAMA and
+ cHRM chunks with the specific values
+ that are consistent with sRGB to be
+ written.
+
+ png_set_iCCP(png_ptr, info_ptr, name, compression_type,
+ profile, proflen);
+
+ name - The profile name.
+
+ compression_type - The compression type; always
+ PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
+ You may give NULL to this argument to
+ ignore it.
+
+ profile - International Color Consortium color
+ profile data. May contain NULs.
+
+ proflen - length of profile data in bytes.
+
+ png_set_sBIT(png_ptr, info_ptr, sig_bit);
+
+ sig_bit - the number of significant bits for
+ (PNG_INFO_sBIT) each of the gray, red,
+ green, and blue channels, whichever are
+ appropriate for the given color type
+ (png_color_16)
+
+ png_set_tRNS(png_ptr, info_ptr, trans_alpha,
+ num_trans, trans_color);
+
+ trans_alpha - array of alpha (transparency)
+ entries for palette (PNG_INFO_tRNS)
+
+ num_trans - number of transparent entries
+ (PNG_INFO_tRNS)
+
+ trans_color - graylevel or color sample values
+ (in order red, green, blue) of the
+ single transparent color for
+ non-paletted images (PNG_INFO_tRNS)
+
+ png_set_hIST(png_ptr, info_ptr, hist);
+
+ hist - histogram of palette (array of
+ png_uint_16) (PNG_INFO_hIST)
+
+ png_set_tIME(png_ptr, info_ptr, mod_time);
+
+ mod_time - time image was last modified
+ (PNG_VALID_tIME)
+
+ png_set_bKGD(png_ptr, info_ptr, background);
+
+ background - background color (of type
+ png_color_16p) (PNG_VALID_bKGD)
+
+ png_set_text(png_ptr, info_ptr, text_ptr, num_text);
+
+ text_ptr - array of png_text holding image
+ comments
+
+ text_ptr[i].compression - type of compression used
+ on "text" PNG_TEXT_COMPRESSION_NONE
+ PNG_TEXT_COMPRESSION_zTXt
+ PNG_ITXT_COMPRESSION_NONE
+ PNG_ITXT_COMPRESSION_zTXt
+ text_ptr[i].key - keyword for comment. Must contain
+ 1-79 characters.
+ text_ptr[i].text - text comments for current
+ keyword. Can be NULL or empty.
+ text_ptr[i].text_length - length of text string,
+ after decompression, 0 for iTXt
+ text_ptr[i].itxt_length - length of itxt string,
+ after decompression, 0 for tEXt/zTXt
+ text_ptr[i].lang - language of comment (NULL or
+ empty for unknown).
+ text_ptr[i].translated_keyword - keyword in UTF-8 (NULL
+ or empty for unknown).
+
+ Note that the itxt_length, lang, and lang_key
+ members of the text_ptr structure only exist when the
+ library is built with iTXt chunk support. Prior to
+ libpng-1.4.0 the library was built by default without
+ iTXt support. Also note that when iTXt is supported,
+ they contain NULL pointers when the "compression"
+ field contains PNG_TEXT_COMPRESSION_NONE or
+ PNG_TEXT_COMPRESSION_zTXt.
+
+ num_text - number of comments
+
+ png_set_sPLT(png_ptr, info_ptr, &palette_ptr,
+ num_spalettes);
+
+ palette_ptr - array of png_sPLT_struct structures
+ to be added to the list of palettes
+ in the info structure.
+ num_spalettes - number of palette structures to be
+ added.
+
+ png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y,
+ unit_type);
+
+ offset_x - positive offset from the left
+ edge of the screen
+
+ offset_y - positive offset from the top
+ edge of the screen
+
+ unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
+
+ png_set_pHYs(png_ptr, info_ptr, res_x, res_y,
+ unit_type);
+
+ res_x - pixels/unit physical resolution
+ in x direction
+
+ res_y - pixels/unit physical resolution
+ in y direction
+
+ unit_type - PNG_RESOLUTION_UNKNOWN,
+ PNG_RESOLUTION_METER
+
+ png_set_sCAL(png_ptr, info_ptr, unit, width, height)
+
+ unit - physical scale units (an integer)
+
+ width - width of a pixel in physical scale units
+
+ height - height of a pixel in physical scale units
+ (width and height are doubles)
+
+ png_set_sCAL_s(png_ptr, info_ptr, unit, width, height)
+
+ unit - physical scale units (an integer)
+
+ width - width of a pixel in physical scale units
+ expressed as a string
+
+ height - height of a pixel in physical scale units
+ (width and height are strings like "2.54")
+
+ png_set_unknown_chunks(png_ptr, info_ptr, &unknowns,
+ num_unknowns)
+
+ unknowns - array of png_unknown_chunk
+ structures holding unknown chunks
+ unknowns[i].name - name of unknown chunk
+ unknowns[i].data - data of unknown chunk
+ unknowns[i].size - size of unknown chunk's data
+ unknowns[i].location - position to write chunk in file
+ 0: do not write chunk
+ PNG_HAVE_IHDR: before PLTE
+ PNG_HAVE_PLTE: before IDAT
+ PNG_AFTER_IDAT: after IDAT
+
+The "location" member is set automatically according to
+what part of the output file has already been written.
+You can change its value after calling png_set_unknown_chunks()
+as demonstrated in pngtest.c. Within each of the "locations",
+the chunks are sequenced according to their position in the
+structure (that is, the value of "i", which is the order in which
+the chunk was either read from the input file or defined with
+png_set_unknown_chunks).
+
+A quick word about text and num_text. text is an array of png_text
+structures. num_text is the number of valid structures in the array.
+Each png_text structure holds a language code, a keyword, a text value,
+and a compression type.
+
+The compression types have the same valid numbers as the compression
+types of the image data. Currently, the only valid number is zero.
+However, you can store text either compressed or uncompressed, unlike
+images, which always have to be compressed. So if you don't want the
+text compressed, set the compression type to PNG_TEXT_COMPRESSION_NONE.
+Because tEXt and zTXt chunks don't have a language field, if you
+specify PNG_TEXT_COMPRESSION_NONE or PNG_TEXT_COMPRESSION_zTXt
+any language code or translated keyword will not be written out.
+
+Until text gets around a few hundred bytes, it is not worth compressing it.
+After the text has been written out to the file, the compression type
+is set to PNG_TEXT_COMPRESSION_NONE_WR or PNG_TEXT_COMPRESSION_zTXt_WR,
+so that it isn't written out again at the end (in case you are calling
+png_write_end() with the same struct).
+
+The keywords that are given in the PNG Specification are:
+
+ Title Short (one line) title or
+ caption for image
+
+ Author Name of image's creator
+
+ Description Description of image (possibly long)
+
+ Copyright Copyright notice
+
+ Creation Time Time of original image creation
+ (usually RFC 1123 format, see below)
+
+ Software Software used to create the image
+
+ Disclaimer Legal disclaimer
+
+ Warning Warning of nature of content
+
+ Source Device used to create the image
+
+ Comment Miscellaneous comment; conversion
+ from other image format
+
+The keyword-text pairs work like this. Keywords should be short
+simple descriptions of what the comment is about. Some typical
+keywords are found in the PNG specification, as is some recommendations
+on keywords. You can repeat keywords in a file. You can even write
+some text before the image and some after. For example, you may want
+to put a description of the image before the image, but leave the
+disclaimer until after, so viewers working over modem connections
+don't have to wait for the disclaimer to go over the modem before
+they start seeing the image. Finally, keywords should be full
+words, not abbreviations. Keywords and text are in the ISO 8859-1
+(Latin-1) character set (a superset of regular ASCII) and can not
+contain NUL characters, and should not contain control or other
+unprintable characters. To make the comments widely readable, stick
+with basic ASCII, and avoid machine specific character set extensions
+like the IBM-PC character set. The keyword must be present, but
+you can leave off the text string on non-compressed pairs.
+Compressed pairs must have a text string, as only the text string
+is compressed anyway, so the compression would be meaningless.
+
+PNG supports modification time via the png_time structure. Two
+conversion routines are provided, png_convert_from_time_t() for
+time_t and png_convert_from_struct_tm() for struct tm. The
+time_t routine uses gmtime(). You don't have to use either of
+these, but if you wish to fill in the png_time structure directly,
+you should provide the time in universal time (GMT) if possible
+instead of your local time. Note that the year number is the full
+year (e.g. 1998, rather than 98 - PNG is year 2000 compliant!), and
+that months start with 1.
+
+If you want to store the time of the original image creation, you should
+use a plain tEXt chunk with the "Creation Time" keyword. This is
+necessary because the "creation time" of a PNG image is somewhat vague,
+depending on whether you mean the PNG file, the time the image was
+created in a non-PNG format, a still photo from which the image was
+scanned, or possibly the subject matter itself. In order to facilitate
+machine-readable dates, it is recommended that the "Creation Time"
+tEXt chunk use RFC 1123 format dates (e.g. "22 May 1997 18:07:10 GMT"),
+although this isn't a requirement. Unlike the tIME chunk, the
+"Creation Time" tEXt chunk is not expected to be automatically changed
+by the software. To facilitate the use of RFC 1123 dates, a function
+png_convert_to_rfc1123_buffer(buffer, png_timep) is provided to
+convert from PNG time to an RFC 1123 format string. The caller must provide
+a writeable buffer of at least 29 bytes.
+
+.SS Writing unknown chunks
+
+You can use the png_set_unknown_chunks function to queue up private chunks
+for writing. You give it a chunk name, location, raw data, and a size. You
+also must use png_set_keep_unknown_chunks() to ensure that libpng will
+handle them. That's all there is to it. The chunks will be written by the
+next following png_write_info_before_PLTE, png_write_info, or png_write_end
+function, depending upon the specified location. Any chunks previously
+read into the info structure's unknown-chunk list will also be written out
+in a sequence that satisfies the PNG specification's ordering rules.
+
+Here is an example of writing two private chunks, prVt and miNE:
+
+ #ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
+ /* Set unknown chunk data */
+ png_unknown_chunk unk_chunk[2];
+ strcpy((char *) unk_chunk[0].name, "prVt";
+ unk_chunk[0].data = (unsigned char *) "PRIVATE DATA";
+ unk_chunk[0].size = strlen(unk_chunk[0].data)+1;
+ unk_chunk[0].location = PNG_HAVE_IHDR;
+ strcpy((char *) unk_chunk[1].name, "miNE";
+ unk_chunk[1].data = (unsigned char *) "MY CHUNK DATA";
+ unk_chunk[1].size = strlen(unk_chunk[0].data)+1;
+ unk_chunk[1].location = PNG_AFTER_IDAT;
+ png_set_unknown_chunks(write_ptr, write_info_ptr,
+ unk_chunk, 2);
+ /* Needed because miNE is not safe-to-copy */
+ png_set_keep_unknown_chunks(png, PNG_HANDLE_CHUNK_ALWAYS,
+ (png_bytep) "miNE", 1);
+ # if PNG_LIBPNG_VER < 10600
+ /* Deal with unknown chunk location bug in 1.5.x and earlier */
+ png_set_unknown_chunk_location(png, info, 0, PNG_HAVE_IHDR);
+ png_set_unknown_chunk_location(png, info, 1, PNG_AFTER_IDAT);
+ # endif
+ # if PNG_LIBPNG_VER < 10500
+ /* PNG_AFTER_IDAT writes two copies of the chunk prior to libpng-1.5.0,
+ * one before IDAT and another after IDAT, so don't use it; only use
+ * PNG_HAVE_IHDR location. This call resets the location previously
+ * set by assignment and png_set_unknown_chunk_location() for chunk 1.
+ */
+ png_set_unknown_chunk_location(png, info, 1, PNG_HAVE_IHDR);
+ # endif
+ #endif
+
+.SS The high-level write interface
+
+At this point there are two ways to proceed; through the high-level
+write interface, or through a sequence of low-level write operations.
+You can use the high-level interface if your image data is present
+in the info structure. All defined output
+transformations are permitted, enabled by the following masks.
+
+ PNG_TRANSFORM_IDENTITY No transformation
+ PNG_TRANSFORM_PACKING Pack 1, 2 and 4-bit samples
+ PNG_TRANSFORM_PACKSWAP Change order of packed
+ pixels to LSB first
+ PNG_TRANSFORM_INVERT_MONO Invert monochrome images
+ PNG_TRANSFORM_SHIFT Normalize pixels to the
+ sBIT depth
+ PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA
+ to BGRA
+ PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
+ to AG
+ PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
+ to transparency
+ PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
+ PNG_TRANSFORM_STRIP_FILLER Strip out filler
+ bytes (deprecated).
+ PNG_TRANSFORM_STRIP_FILLER_BEFORE Strip out leading
+ filler bytes
+ PNG_TRANSFORM_STRIP_FILLER_AFTER Strip out trailing
+ filler bytes
+
+If you have valid image data in the info structure (you can use
+png_set_rows() to put image data in the info structure), simply do this:
+
+ png_write_png(png_ptr, info_ptr, png_transforms, NULL)
+
+where png_transforms is an integer containing the bitwise OR of some set of
+transformation flags. This call is equivalent to png_write_info(),
+followed the set of transformations indicated by the transform mask,
+then png_write_image(), and finally png_write_end().
+
+(The final parameter of this call is not yet used. Someday it might point
+to transformation parameters required by some future output transform.)
+
+You must use png_transforms and not call any png_set_transform() functions
+when you use png_write_png().
+
+.SS The low-level write interface
+
+If you are going the low-level route instead, you are now ready to
+write all the file information up to the actual image data. You do
+this with a call to png_write_info().
+
+ png_write_info(png_ptr, info_ptr);
+
+Note that there is one transformation you may need to do before
+png_write_info(). In PNG files, the alpha channel in an image is the
+level of opacity. If your data is supplied as a level of transparency,
+you can invert the alpha channel before you write it, so that 0 is
+fully transparent and 255 (in 8-bit or paletted images) or 65535
+(in 16-bit images) is fully opaque, with
+
+ png_set_invert_alpha(png_ptr);
+
+This must appear before png_write_info() instead of later with the
+other transformations because in the case of paletted images the tRNS
+chunk data has to be inverted before the tRNS chunk is written. If
+your image is not a paletted image, the tRNS data (which in such cases
+represents a single color to be rendered as transparent) won't need to
+be changed, and you can safely do this transformation after your
+png_write_info() call.
+
+If you need to write a private chunk that you want to appear before
+the PLTE chunk when PLTE is present, you can write the PNG info in
+two steps, and insert code to write your own chunk between them:
+
+ png_write_info_before_PLTE(png_ptr, info_ptr);
+ png_set_unknown_chunks(png_ptr, info_ptr, ...);
+ png_write_info(png_ptr, info_ptr);
+
+After you've written the file information, you can set up the library
+to handle any special transformations of the image data. The various
+ways to transform the data will be described in the order that they
+should occur. This is important, as some of these change the color
+type and/or bit depth of the data, and some others only work on
+certain color types and bit depths. Even though each transformation
+checks to see if it has data that it can do something with, you should
+make sure to only enable a transformation if it will be valid for the
+data. For example, don't swap red and blue on grayscale data.
+
+PNG files store RGB pixels packed into 3 or 6 bytes. This code tells
+the library to strip input data that has 4 or 8 bytes per pixel down
+to 3 or 6 bytes (or strip 2 or 4-byte grayscale+filler data to 1 or 2
+bytes per pixel).
+
+ png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
+
+where the 0 is unused, and the location is either PNG_FILLER_BEFORE or
+PNG_FILLER_AFTER, depending upon whether the filler byte in the pixel
+is stored XRGB or RGBX.
+
+PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
+they can, resulting in, for example, 8 pixels per byte for 1 bit files.
+If the data is supplied at 1 pixel per byte, use this code, which will
+correctly pack the pixels into a single byte:
+
+ png_set_packing(png_ptr);
+
+PNG files reduce possible bit depths to 1, 2, 4, 8, and 16. If your
+data is of another bit depth, you can write an sBIT chunk into the
+file so that decoders can recover the original data if desired.
+
+ /* Set the true bit depth of the image data */
+ if (color_type & PNG_COLOR_MASK_COLOR)
+ {
+ sig_bit.red = true_bit_depth;
+ sig_bit.green = true_bit_depth;
+ sig_bit.blue = true_bit_depth;
+ }
+
+ else
+ {
+ sig_bit.gray = true_bit_depth;
+ }
+
+ if (color_type & PNG_COLOR_MASK_ALPHA)
+ {
+ sig_bit.alpha = true_bit_depth;
+ }
+
+ png_set_sBIT(png_ptr, info_ptr, &sig_bit);
+
+If the data is stored in the row buffer in a bit depth other than
+one supported by PNG (e.g. 3 bit data in the range 0-7 for a 4-bit PNG),
+this will scale the values to appear to be the correct bit depth as
+is required by PNG.
+
+ png_set_shift(png_ptr, &sig_bit);
+
+PNG files store 16-bit pixels in network byte order (big-endian,
+ie. most significant bits first). This code would be used if they are
+supplied the other way (little-endian, i.e. least significant bits
+first, the way PCs store them):
+
+ if (bit_depth > 8)
+ png_set_swap(png_ptr);
+
+If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
+need to change the order the pixels are packed into bytes, you can use:
+
+ if (bit_depth < 8)
+ png_set_packswap(png_ptr);
+
+PNG files store 3 color pixels in red, green, blue order. This code
+would be used if they are supplied as blue, green, red:
+
+ png_set_bgr(png_ptr);
+
+PNG files describe monochrome as black being zero and white being
+one. This code would be used if the pixels are supplied with this reversed
+(black being one and white being zero):
+
+ png_set_invert_mono(png_ptr);
+
+Finally, you can write your own transformation function if none of
+the existing ones meets your needs. This is done by setting a callback
+with
+
+ png_set_write_user_transform_fn(png_ptr,
+ write_transform_fn);
+
+You must supply the function
+
+ void write_transform_fn(png_structp png_ptr, png_row_infop
+ row_info, png_bytep data)
+
+See pngtest.c for a working example. Your function will be called
+before any of the other transformations are processed. If supported
+libpng also supplies an information routine that may be called from
+your callback:
+
+ png_get_current_row_number(png_ptr);
+ png_get_current_pass_number(png_ptr);
+
+This returns the current row passed to the transform. With interlaced
+images the value returned is the row in the input sub-image image. Use
+PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
+find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass).
+
+The discussion of interlace handling above contains more information on how to
+use these values.
+
+You can also set up a pointer to a user structure for use by your
+callback function.
+
+ png_set_user_transform_info(png_ptr, user_ptr, 0, 0);
+
+The user_channels and user_depth parameters of this function are ignored
+when writing; you can set them to zero as shown.
+
+You can retrieve the pointer via the function png_get_user_transform_ptr().
+For example:
+
+ voidp write_user_transform_ptr =
+ png_get_user_transform_ptr(png_ptr);
+
+It is possible to have libpng flush any pending output, either manually,
+or automatically after a certain number of lines have been written. To
+flush the output stream a single time call:
+
+ png_write_flush(png_ptr);
+
+and to have libpng flush the output stream periodically after a certain
+number of scanlines have been written, call:
+
+ png_set_flush(png_ptr, nrows);
+
+Note that the distance between rows is from the last time png_write_flush()
+was called, or the first row of the image if it has never been called.
+So if you write 50 lines, and then png_set_flush 25, it will flush the
+output on the next scanline, and every 25 lines thereafter, unless
+png_write_flush() is called before 25 more lines have been written.
+If nrows is too small (less than about 10 lines for a 640 pixel wide
+RGB image) the image compression may decrease noticeably (although this
+may be acceptable for real-time applications). Infrequent flushing will
+only degrade the compression performance by a few percent over images
+that do not use flushing.
+
+.SS Writing the image data
+
+That's it for the transformations. Now you can write the image data.
+The simplest way to do this is in one function call. If you have the
+whole image in memory, you can just call png_write_image() and libpng
+will write the image. You will need to pass in an array of pointers to
+each row. This function automatically handles interlacing, so you don't
+need to call png_set_interlace_handling() or call this function multiple
+times, or any of that other stuff necessary with png_write_rows().
+
+ png_write_image(png_ptr, row_pointers);
+
+where row_pointers is:
+
+ png_byte *row_pointers[height];
+
+You can point to void or char or whatever you use for pixels.
+
+If you don't want to write the whole image at once, you can
+use png_write_rows() instead. If the file is not interlaced,
+this is simple:
+
+ png_write_rows(png_ptr, row_pointers,
+ number_of_rows);
+
+row_pointers is the same as in the png_write_image() call.
+
+If you are just writing one row at a time, you can do this with
+a single row_pointer instead of an array of row_pointers:
+
+ png_bytep row_pointer = row;
+
+ png_write_row(png_ptr, row_pointer);
+
+When the file is interlaced, things can get a good deal more complicated.
+The only currently (as of the PNG Specification version 1.2, dated July
+1999) defined interlacing scheme for PNG files is the "Adam7" interlace
+scheme, that breaks down an image into seven smaller images of varying
+size. libpng will build these images for you, or you can do them
+yourself. If you want to build them yourself, see the PNG specification
+for details of which pixels to write when.
+
+If you don't want libpng to handle the interlacing details, just
+use png_set_interlace_handling() and call png_write_rows() the
+correct number of times to write all the sub-images
+(png_set_interlace_handling() returns the number of sub-images.)
+
+If you want libpng to build the sub-images, call this before you start
+writing any rows:
+
+ number_of_passes = png_set_interlace_handling(png_ptr);
+
+This will return the number of passes needed. Currently, this is seven,
+but may change if another interlace type is added.
+
+Then write the complete image number_of_passes times.
+
+ png_write_rows(png_ptr, row_pointers, number_of_rows);
+
+Think carefully before you write an interlaced image. Typically code that
+reads such images reads all the image data into memory, uncompressed, before
+doing any processing. Only code that can display an image on the fly can
+take advantage of the interlacing and even then the image has to be exactly
+the correct size for the output device, because scaling an image requires
+adjacent pixels and these are not available until all the passes have been
+read.
+
+If you do write an interlaced image you will hardly ever need to handle
+the interlacing yourself. Call png_set_interlace_handling() and use the
+approach described above.
+
+The only time it is conceivable that you will really need to write an
+interlaced image pass-by-pass is when you have read one pass by pass and
+made some pixel-by-pixel transformation to it, as described in the read
+code above. In this case use the PNG_PASS_ROWS and PNG_PASS_COLS macros
+to determine the size of each sub-image in turn and simply write the rows
+you obtained from the read code.
+
+.SS Finishing a sequential write
+
+After you are finished writing the image, you should finish writing
+the file. If you are interested in writing comments or time, you should
+pass an appropriately filled png_info pointer. If you are not interested,
+you can pass NULL.
+
+ png_write_end(png_ptr, info_ptr);
+
+When you are done, you can free all memory used by libpng like this:
+
+ png_destroy_write_struct(&png_ptr, &info_ptr);
+
+It is also possible to individually free the info_ptr members that
+point to libpng-allocated storage with the following function:
+
+ png_free_data(png_ptr, info_ptr, mask, seq)
+
+ mask - identifies data to be freed, a mask
+ containing the bitwise OR of one or
+ more of
+ PNG_FREE_PLTE, PNG_FREE_TRNS,
+ PNG_FREE_HIST, PNG_FREE_ICCP,
+ PNG_FREE_PCAL, PNG_FREE_ROWS,
+ PNG_FREE_SCAL, PNG_FREE_SPLT,
+ PNG_FREE_TEXT, PNG_FREE_UNKN,
+ or simply PNG_FREE_ALL
+
+ seq - sequence number of item to be freed
+ (\-1 for all items)
+
+This function may be safely called when the relevant storage has
+already been freed, or has not yet been allocated, or was allocated
+by the user and not by libpng, and will in those cases do nothing.
+The "seq" parameter is ignored if only one item of the selected data
+type, such as PLTE, is allowed. If "seq" is not \-1, and multiple items
+are allowed for the data type identified in the mask, such as text or
+sPLT, only the n'th item in the structure is freed, where n is "seq".
+
+If you allocated data such as a palette that you passed in to libpng
+with png_set_*, you must not free it until just before the call to
+png_destroy_write_struct().
+
+The default behavior is only to free data that was allocated internally
+by libpng. This can be changed, so that libpng will not free the data,
+or so that it will free data that was allocated by the user with png_malloc()
+or png_calloc() and passed in via a png_set_*() function, with
+
+ png_data_freer(png_ptr, info_ptr, freer, mask)
+
+ freer - one of
+ PNG_DESTROY_WILL_FREE_DATA
+ PNG_SET_WILL_FREE_DATA
+ PNG_USER_WILL_FREE_DATA
+
+ mask - which data elements are affected
+ same choices as in png_free_data()
+
+For example, to transfer responsibility for some data from a read structure
+to a write structure, you could use
+
+ png_data_freer(read_ptr, read_info_ptr,
+ PNG_USER_WILL_FREE_DATA,
+ PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
+
+ png_data_freer(write_ptr, write_info_ptr,
+ PNG_DESTROY_WILL_FREE_DATA,
+ PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
+
+thereby briefly reassigning responsibility for freeing to the user but
+immediately afterwards reassigning it once more to the write_destroy
+function. Having done this, it would then be safe to destroy the read
+structure and continue to use the PLTE, tRNS, and hIST data in the write
+structure.
+
+This function only affects data that has already been allocated.
+You can call this function before calling after the png_set_*() functions
+to control whether the user or png_destroy_*() is supposed to free the data.
+When the user assumes responsibility for libpng-allocated data, the
+application must use
+png_free() to free it, and when the user transfers responsibility to libpng
+for data that the user has allocated, the user must have used png_malloc()
+or png_calloc() to allocate it.
+
+If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
+separately, do not transfer responsibility for freeing text_ptr to libpng,
+because when libpng fills a png_text structure it combines these members with
+the key member, and png_free_data() will free only text_ptr.key. Similarly,
+if you transfer responsibility for free'ing text_ptr from libpng to your
+application, your application must not separately free those members.
+For a more compact example of writing a PNG image, see the file example.c.
+
+.SH V. Simplified API
+
+The simplified API, which became available in libpng-1.6.0, hides the details
+of both libpng and the PNG file format itself.
+It allows PNG files to be read into a very limited number of
+in-memory bitmap formats or to be written from the same formats. If these
+formats do not accommodate your needs then you can, and should, use the more
+sophisticated APIs above - these support a wide variety of in-memory formats
+and a wide variety of sophisticated transformations to those formats as well
+as a wide variety of APIs to manipulate ancilliary information.
+
+To read a PNG file using the simplified API:
+
+ 1) Declare a 'png_image' structure (see below) on the stack, set the
+ version field to PNG_IMAGE_VERSION and the 'opaque' pointer to NULL
+ (this is REQUIRED, your program may crash if you don't do it.)
+
+ 2) Call the appropriate png_image_begin_read... function.
+
+ 3) Set the png_image 'format' member to the required sample format.
+
+ 4) Allocate a buffer for the image and, if required, the color-map.
+
+ 5) Call png_image_finish_read to read the image and, if required, the
+ color-map into your buffers.
+
+There are no restrictions on the format of the PNG input itself; all valid
+color types, bit depths, and interlace methods are acceptable, and the
+input image is transformed as necessary to the requested in-memory format
+during the png_image_finish_read() step. The only caveat is that if you
+request a color-mapped image from a PNG that is full-color or makes
+complex use of an alpha channel the transformation is extremely lossy and the
+result may look terrible.
+
+To write a PNG file using the simplified API:
+
+ 1) Declare a 'png_image' structure on the stack and memset()
+ it to all zero.
+
+ 2) Initialize the members of the structure that describe the
+ image, setting the 'format' member to the format of the
+ image samples.
+
+ 3) Call the appropriate png_image_write... function with a
+ pointer to the image and, if necessary, the color-map to write
+ the PNG data.
+
+png_image is a structure that describes the in-memory format of an image
+when it is being read or defines the in-memory format of an image that you
+need to write. The "png_image" structure contains the following members:
+
+ png_controlp opaque Initialize to NULL, free with png_image_free
+ png_uint_32 version Set to PNG_IMAGE_VERSION
+ png_uint_32 width Image width in pixels (columns)
+ png_uint_32 height Image height in pixels (rows)
+ png_uint_32 format Image format as defined below
+ png_uint_32 flags A bit mask containing informational flags
+ png_uint_32 colormap_entries; Number of entries in the color-map
+ png_uint_32 warning_or_error;
+ char message[64];
+
+In the event of an error or warning the "warning_or_error"
+field will be set to a non-zero value and the 'message' field will contain
+a '\0' terminated string with the libpng error or warning message. If both
+warnings and an error were encountered, only the error is recorded. If there
+are multiple warnings, only the first one is recorded.
+
+The upper 30 bits of the "warning_or_error" value are reserved; the low two
+bits contain a two bit code such that a value more than 1 indicates a failure
+in the API just called:
+
+ 0 - no warning or error
+ 1 - warning
+ 2 - error
+ 3 - error preceded by warning
+
+The pixels (samples) of the image have one to four channels whose components
+have original values in the range 0 to 1.0:
+
+ 1: A single gray or luminance channel (G).
+ 2: A gray/luminance channel and an alpha channel (GA).
+ 3: Three red, green, blue color channels (RGB).
+ 4: Three color channels and an alpha channel (RGBA).
+
+The channels are encoded in one of two ways:
+
+ a) As a small integer, value 0..255, contained in a single byte. For the
+alpha channel the original value is simply value/255. For the color or
+luminance channels the value is encoded according to the sRGB specification
+and matches the 8-bit format expected by typical display devices.
+
+The color/gray channels are not scaled (pre-multiplied) by the alpha
+channel and are suitable for passing to color management software.
+
+ b) As a value in the range 0..65535, contained in a 2-byte integer, in
+the native byte order of the platform on which the application is running.
+All channels can be converted to the original value by dividing by 65535; all
+channels are linear. Color channels use the RGB encoding (RGB end-points) of
+the sRGB specification. This encoding is identified by the
+PNG_FORMAT_FLAG_LINEAR flag below.
+
+When the simplified API needs to convert between sRGB and linear colorspaces,
+the actual sRGB transfer curve defined in the sRGB specification (see the
+article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+approximation used elsewhere in libpng.
+
+When an alpha channel is present it is expected to denote pixel coverage
+of the color or luminance channels and is returned as an associated alpha
+channel: the color/gray channels are scaled (pre-multiplied) by the alpha
+value.
+
+The samples are either contained directly in the image data, between 1 and 8
+bytes per pixel according to the encoding, or are held in a color-map indexed
+by bytes in the image data. In the case of a color-map the color-map entries
+are individual samples, encoded as above, and the image data has one byte per
+pixel to select the relevant sample from the color-map.
+
+PNG_FORMAT_*
+
+The #defines to be used in png_image::format. Each #define identifies a
+particular layout of channel data and, if present, alpha values. There are
+separate defines for each of the two component encodings.
+
+A format is built up using single bit flag values. All combinations are
+valid. Formats can be built up from the flag values or you can use one of
+the predefined values below. When testing formats always use the FORMAT_FLAG
+macros to test for individual features - future versions of the library may
+add new flags.
+
+When reading or writing color-mapped images the format should be set to the
+format of the entries in the color-map then png_image_{read,write}_colormap
+called to read or write the color-map and set the format correctly for the
+image data. Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly!
+
+NOTE: libpng can be built with particular features disabled. If you see
+compiler errors because the definition of one of the following flags has been
+compiled out it is because libpng does not have the required support. It is
+possible, however, for the libpng configuration to enable the format on just
+read or just write; in that case you may see an error at run time.
+You can guard against this by checking for the definition of the
+appropriate "_SUPPORTED" macro, one of:
+
+ PNG_SIMPLIFIED_{READ,WRITE}_{BGR,AFIRST}_SUPPORTED
+
+ PNG_FORMAT_FLAG_ALPHA format with an alpha channel
+ PNG_FORMAT_FLAG_COLOR color format: otherwise grayscale
+ PNG_FORMAT_FLAG_LINEAR 2-byte channels else 1-byte
+ PNG_FORMAT_FLAG_COLORMAP image data is color-mapped
+ PNG_FORMAT_FLAG_BGR BGR colors, else order is RGB
+ PNG_FORMAT_FLAG_AFIRST alpha channel comes first
+
+Supported formats are as follows. Future versions of libpng may support more
+formats; for compatibility with older versions simply check if the format
+macro is defined using #ifdef. These defines describe the in-memory layout
+of the components of the pixels of the image.
+
+First the single byte (sRGB) formats:
+
+ PNG_FORMAT_GRAY
+ PNG_FORMAT_GA
+ PNG_FORMAT_AG
+ PNG_FORMAT_RGB
+ PNG_FORMAT_BGR
+ PNG_FORMAT_RGBA
+ PNG_FORMAT_ARGB
+ PNG_FORMAT_BGRA
+ PNG_FORMAT_ABGR
+
+Then the linear 2-byte formats. When naming these "Y" is used to
+indicate a luminance (gray) channel. The component order within the pixel
+is always the same - there is no provision for swapping the order of the
+components in the linear format. The components are 16-bit integers in
+the native byte order for your platform, and there is no provision for
+swapping the bytes to a different endian condition.
+
+ PNG_FORMAT_LINEAR_Y
+ PNG_FORMAT_LINEAR_Y_ALPHA
+ PNG_FORMAT_LINEAR_RGB
+ PNG_FORMAT_LINEAR_RGB_ALPHA
+
+With color-mapped formats the image data is one byte for each pixel. The byte
+is an index into the color-map which is formatted as above. To obtain a
+color-mapped format it is sufficient just to add the PNG_FOMAT_FLAG_COLORMAP
+to one of the above definitions, or you can use one of the definitions below.
+
+ PNG_FORMAT_RGB_COLORMAP
+ PNG_FORMAT_BGR_COLORMAP
+ PNG_FORMAT_RGBA_COLORMAP
+ PNG_FORMAT_ARGB_COLORMAP
+ PNG_FORMAT_BGRA_COLORMAP
+ PNG_FORMAT_ABGR_COLORMAP
+
+PNG_IMAGE macros
+
+These are convenience macros to derive information from a png_image
+structure. The PNG_IMAGE_SAMPLE_ macros return values appropriate to the
+actual image sample values - either the entries in the color-map or the
+pixels in the image. The PNG_IMAGE_PIXEL_ macros return corresponding values
+for the pixels and will always return 1 for color-mapped formats. The
+remaining macros return information about the rows in the image and the
+complete image.
+
+NOTE: All the macros that take a png_image::format parameter are compile time
+constants if the format parameter is, itself, a constant. Therefore these
+macros can be used in array declarations and case labels where required.
+Similarly the macros are also pre-processor constants (sizeof is not used) so
+they can be used in #if tests.
+
+ PNG_IMAGE_SAMPLE_CHANNELS(fmt)
+ Returns the total number of channels in a given format: 1..4
+
+ PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt)
+ Returns the size in bytes of a single component of a pixel or color-map
+ entry (as appropriate) in the image: 1 or 2.
+
+ PNG_IMAGE_SAMPLE_SIZE(fmt)
+ This is the size of the sample data for one sample. If the image is
+ color-mapped it is the size of one color-map entry (and image pixels are
+ one byte in size), otherwise it is the size of one image pixel.
+
+ PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)
+ The maximum size of the color-map required by the format expressed in a
+ count of components. This can be used to compile-time allocate a
+ color-map:
+
+ png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)];
+
+ png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)];
+
+ Alternatively use the PNG_IMAGE_COLORMAP_SIZE macro below to use the
+ information from one of the png_image_begin_read_ APIs and dynamically
+ allocate the required memory.
+
+ PNG_IMAGE_COLORMAP_SIZE(fmt)
+ The size of the color-map required by the format; this is the size of the
+ color-map buffer passed to the png_image_{read,write}_colormap APIs. It is
+ a fixed number determined by the format so can easily be allocated on the
+ stack if necessary.
+
+Corresponding information about the pixels
+
+ PNG_IMAGE_PIXEL_CHANNELS(fmt)
+ The number of separate channels (components) in a pixel; 1 for a
+ color-mapped image.
+
+ PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)\
+ The size, in bytes, of each component in a pixel; 1 for a color-mapped
+ image.
+
+ PNG_IMAGE_PIXEL_SIZE(fmt)
+ The size, in bytes, of a complete pixel; 1 for a color-mapped image.
+
+Information about the whole row, or whole image
+
+ PNG_IMAGE_ROW_STRIDE(image)
+ Returns the total number of components in a single row of the image; this
+ is the minimum 'row stride', the minimum count of components between each
+ row. For a color-mapped image this is the minimum number of bytes in a
+ row.
+
+ If you need the stride measured in bytes, row_stride_bytes is
+ PNG_IMAGE_ROW_STRIDE(image) * PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)
+ plus any padding bytes that your application might need, for example
+ to start the next row on a 4-byte boundary.
+
+ PNG_IMAGE_BUFFER_SIZE(image, row_stride)
+ Return the size, in bytes, of an image buffer given a png_image and a row
+ stride - the number of components to leave space for in each row.
+
+ PNG_IMAGE_SIZE(image)
+ Return the size, in bytes, of the image in memory given just a png_image;
+ the row stride is the minimum stride required for the image.
+
+ PNG_IMAGE_COLORMAP_SIZE(image)
+ Return the size, in bytes, of the color-map of this image. If the image
+ format is not a color-map format this will return a size sufficient for
+ 256 entries in the given format; check PNG_FORMAT_FLAG_COLORMAP if
+ you don't want to allocate a color-map in this case.
+
+PNG_IMAGE_FLAG_*
+
+Flags containing additional information about the image are held in
+the 'flags' field of png_image.
+
+ PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB == 0x01
+ This indicates the the RGB values of the in-memory bitmap do not
+ correspond to the red, green and blue end-points defined by sRGB.
+
+ PNG_IMAGE_FLAG_FAST == 0x02
+ On write emphasise speed over compression; the resultant PNG file will be
+ larger but will be produced significantly faster, particular for large
+ images. Do not use this option for images which will be distributed, only
+ used it when producing intermediate files that will be read back in
+ repeatedly. For a typical 24-bit image the option will double the read
+ speed at the cost of increasing the image size by 25%, however for many
+ more compressible images the PNG file can be 10 times larger with only a
+ slight speed gain.
+
+ PNG_IMAGE_FLAG_16BIT_sRGB == 0x04
+ On read if the image is a 16-bit per component image and there is no gAMA
+ or sRGB chunk assume that the components are sRGB encoded. Notice that
+ images output by the simplified API always have gamma information; setting
+ this flag only affects the interpretation of 16-bit images from an
+ external source. It is recommended that the application expose this flag
+ to the user; the user can normally easily recognize the difference between
+ linear and sRGB encoding. This flag has no effect on write - the data
+ passed to the write APIs must have the correct encoding (as defined
+ above.)
+
+ If the flag is not set (the default) input 16-bit per component data is
+ assumed to be linear.
+
+ NOTE: the flag can only be set after the png_image_begin_read_ call,
+ because that call initializes the 'flags' field.
+
+READ APIs
+
+ The png_image passed to the read APIs must have been initialized by setting
+ the png_controlp field 'opaque' to NULL (or, better, memset the whole thing.)
+
+ int png_image_begin_read_from_file( png_imagep image,
+ const char *file_name)
+
+ The named file is opened for read and the image header
+ is filled in from the PNG header in the file.
+
+ int png_image_begin_read_from_stdio (png_imagep image,
+ FILE* file)
+
+ The PNG header is read from the stdio FILE object.
+
+ int png_image_begin_read_from_memory(png_imagep image,
+ png_const_voidp memory, png_size_t size)
+
+ The PNG header is read from the given memory buffer.
+
+ int png_image_finish_read(png_imagep image,
+ png_colorp background, void *buffer,
+ png_int_32 row_stride, void *colormap));
+
+ Finish reading the image into the supplied buffer and
+ clean up the png_image structure.
+
+ row_stride is the step, in png_byte or png_uint_16 units
+ as appropriate, between adjacent rows. A positive stride
+ indicates that the top-most row is first in the buffer -
+ the normal top-down arrangement. A negative stride
+ indicates that the bottom-most row is first in the buffer.
+
+ background need only be supplied if an alpha channel must
+ be removed from a png_byte format and the removal is to be
+ done by compositing on a solid color; otherwise it may be
+ NULL and any composition will be done directly onto the
+ buffer. The value is an sRGB color to use for the
+ background, for grayscale output the green channel is used.
+
+ For linear output removing the alpha channel is always done
+ by compositing on black.
+
+ void png_image_free(png_imagep image)
+
+ Free any data allocated by libpng in image->opaque,
+ setting the pointer to NULL. May be called at any time
+ after the structure is initialized.
+
+When the simplified API needs to convert between sRGB and linear colorspaces,
+the actual sRGB transfer curve defined in the sRGB specification (see the
+article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+approximation used elsewhere in libpng.
+
+WRITE APIS
+
+For write you must initialize a png_image structure to describe the image to
+be written:
+
+ version: must be set to PNG_IMAGE_VERSION
+ opaque: must be initialized to NULL
+ width: image width in pixels
+ height: image height in rows
+ format: the format of the data you wish to write
+ flags: set to 0 unless one of the defined flags applies; set
+ PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB for color format images
+ where the RGB values do not correspond to the colors in sRGB.
+ colormap_entries: set to the number of entries in the color-map (0 to 256)
+
+ int png_image_write_to_file, (png_imagep image,
+ const char *file, int convert_to_8bit, const void *buffer,
+ png_int_32 row_stride, const void *colormap));
+
+ Write the image to the named file.
+
+ int png_image_write_to_stdio(png_imagep image, FILE *file,
+ int convert_to_8_bit, const void *buffer,
+ png_int_32 row_stride, const void *colormap)
+
+ Write the image to the given (FILE*).
+
+With all write APIs if image is in one of the linear formats with
+(png_uint_16) data then setting convert_to_8_bit will cause the output to be
+a (png_byte) PNG gamma encoded according to the sRGB specification, otherwise
+a 16-bit linear encoded PNG file is written.
+
+With all APIs row_stride is handled as in the read APIs - it is the spacing
+from one row to the next in component sized units (float) and if negative
+indicates a bottom-up row layout in the buffer. If you pass zero, libpng will
+calculate the row_stride for you from the width and number of channels.
+
+Note that the write API does not support interlacing, sub-8-bit pixels,
+indexed (paletted) images, or most ancillary chunks.
+
+.SH VI. Modifying/Customizing libpng
+
+There are two issues here. The first is changing how libpng does
+standard things like memory allocation, input/output, and error handling.
+The second deals with more complicated things like adding new chunks,
+adding new transformations, and generally changing how libpng works.
+Both of those are compile-time issues; that is, they are generally
+determined at the time the code is written, and there is rarely a need
+to provide the user with a means of changing them.
+
+Memory allocation, input/output, and error handling
+
+All of the memory allocation, input/output, and error handling in libpng
+goes through callbacks that are user-settable. The default routines are
+in pngmem.c, pngrio.c, pngwio.c, and pngerror.c, respectively. To change
+these functions, call the appropriate png_set_*_fn() function.
+
+Memory allocation is done through the functions png_malloc(), png_calloc(),
+and png_free(). The png_malloc() and png_free() functions currently just
+call the standard C functions and png_calloc() calls png_malloc() and then
+clears the newly allocated memory to zero; note that png_calloc(png_ptr, size)
+is not the same as the calloc(number, size) function provided by stdlib.h.
+There is limited support for certain systems with segmented memory
+architectures and the types of pointers declared by png.h match this; you
+will have to use appropriate pointers in your application. If you prefer
+to use a different method of allocating and freeing data, you can use
+png_create_read_struct_2() or png_create_write_struct_2() to register your
+own functions as described above. These functions also provide a void
+pointer that can be retrieved via
+
+ mem_ptr=png_get_mem_ptr(png_ptr);
+
+Your replacement memory functions must have prototypes as follows:
+
+ png_voidp malloc_fn(png_structp png_ptr,
+ png_alloc_size_t size);
+
+ void free_fn(png_structp png_ptr, png_voidp ptr);
+
+Your malloc_fn() must return NULL in case of failure. The png_malloc()
+function will normally call png_error() if it receives a NULL from the
+system memory allocator or from your replacement malloc_fn().
+
+Your free_fn() will never be called with a NULL ptr, since libpng's
+png_free() checks for NULL before calling free_fn().
+
+Input/Output in libpng is done through png_read() and png_write(),
+which currently just call fread() and fwrite(). The FILE * is stored in
+png_struct and is initialized via png_init_io(). If you wish to change
+the method of I/O, the library supplies callbacks that you can set
+through the function png_set_read_fn() and png_set_write_fn() at run
+time, instead of calling the png_init_io() function. These functions
+also provide a void pointer that can be retrieved via the function
+png_get_io_ptr(). For example:
+
+ png_set_read_fn(png_structp read_ptr,
+ voidp read_io_ptr, png_rw_ptr read_data_fn)
+
+ png_set_write_fn(png_structp write_ptr,
+ voidp write_io_ptr, png_rw_ptr write_data_fn,
+ png_flush_ptr output_flush_fn);
+
+ voidp read_io_ptr = png_get_io_ptr(read_ptr);
+ voidp write_io_ptr = png_get_io_ptr(write_ptr);
+
+The replacement I/O functions must have prototypes as follows:
+
+ void user_read_data(png_structp png_ptr,
+ png_bytep data, png_size_t length);
+
+ void user_write_data(png_structp png_ptr,
+ png_bytep data, png_size_t length);
+
+ void user_flush_data(png_structp png_ptr);
+
+The user_read_data() function is responsible for detecting and
+handling end-of-data errors.
+
+Supplying NULL for the read, write, or flush functions sets them back
+to using the default C stream functions, which expect the io_ptr to
+point to a standard *FILE structure. It is probably a mistake
+to use NULL for one of write_data_fn and output_flush_fn but not both
+of them, unless you have built libpng with PNG_NO_WRITE_FLUSH defined.
+It is an error to read from a write stream, and vice versa.
+
+Error handling in libpng is done through png_error() and png_warning().
+Errors handled through png_error() are fatal, meaning that png_error()
+should never return to its caller. Currently, this is handled via
+setjmp() and longjmp() (unless you have compiled libpng with
+PNG_NO_SETJMP, in which case it is handled via PNG_ABORT()),
+but you could change this to do things like exit() if you should wish,
+as long as your function does not return.
+
+On non-fatal errors, png_warning() is called
+to print a warning message, and then control returns to the calling code.
+By default png_error() and png_warning() print a message on stderr via
+fprintf() unless the library is compiled with PNG_NO_CONSOLE_IO defined
+(because you don't want the messages) or PNG_NO_STDIO defined (because
+fprintf() isn't available). If you wish to change the behavior of the error
+functions, you will need to set up your own message callbacks. These
+functions are normally supplied at the time that the png_struct is created.
+It is also possible to redirect errors and warnings to your own replacement
+functions after png_create_*_struct() has been called by calling:
+
+ png_set_error_fn(png_structp png_ptr,
+ png_voidp error_ptr, png_error_ptr error_fn,
+ png_error_ptr warning_fn);
+
+ png_voidp error_ptr = png_get_error_ptr(png_ptr);
+
+If NULL is supplied for either error_fn or warning_fn, then the libpng
+default function will be used, calling fprintf() and/or longjmp() if a
+problem is encountered. The replacement error functions should have
+parameters as follows:
+
+ void user_error_fn(png_structp png_ptr,
+ png_const_charp error_msg);
+
+ void user_warning_fn(png_structp png_ptr,
+ png_const_charp warning_msg);
+
+The motivation behind using setjmp() and longjmp() is the C++ throw and
+catch exception handling methods. This makes the code much easier to write,
+as there is no need to check every return code of every function call.
+However, there are some uncertainties about the status of local variables
+after a longjmp, so the user may want to be careful about doing anything
+after setjmp returns non-zero besides returning itself. Consult your
+compiler documentation for more details. For an alternative approach, you
+may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net),
+which is illustrated in pngvalid.c and in contrib/visupng.
+
+Beginning in libpng-1.4.0, the png_set_benign_errors() API became available.
+You can use this to handle certain errors (normally handled as errors)
+as warnings.
+
+ png_set_benign_errors (png_ptr, int allowed);
+
+ allowed: 0: treat png_benign_error() as an error.
+ 1: treat png_benign_error() as a warning.
+
+As of libpng-1.6.0, the default condition is to treat benign errors as
+warnings while reading and as errors while writing.
+
+.SS Custom chunks
+
+If you need to read or write custom chunks, you may need to get deeper
+into the libpng code. The library now has mechanisms for storing
+and writing chunks of unknown type; you can even declare callbacks
+for custom chunks. However, this may not be good enough if the
+library code itself needs to know about interactions between your
+chunk and existing `intrinsic' chunks.
+
+If you need to write a new intrinsic chunk, first read the PNG
+specification. Acquire a first level of understanding of how it works.
+Pay particular attention to the sections that describe chunk names,
+and look at how other chunks were designed, so you can do things
+similarly. Second, check out the sections of libpng that read and
+write chunks. Try to find a chunk that is similar to yours and use
+it as a template. More details can be found in the comments inside
+the code. It is best to handle private or unknown chunks in a generic method,
+via callback functions, instead of by modifying libpng functions. This
+is illustrated in pngtest.c, which uses a callback function to handle a
+private "vpAg" chunk and the new "sTER" chunk, which are both unknown to
+libpng.
+
+If you wish to write your own transformation for the data, look through
+the part of the code that does the transformations, and check out some of
+the simpler ones to get an idea of how they work. Try to find a similar
+transformation to the one you want to add and copy off of it. More details
+can be found in the comments inside the code itself.
+
+.SS Configuring for gui/windowing platforms:
+
+You will need to write new error and warning functions that use the GUI
+interface, as described previously, and set them to be the error and
+warning functions at the time that png_create_*_struct() is called,
+in order to have them available during the structure initialization.
+They can be changed later via png_set_error_fn(). On some compilers,
+you may also have to change the memory allocators (png_malloc, etc.).
+
+.SS Configuring zlib:
+
+There are special functions to configure the compression. Perhaps the
+most useful one changes the compression level, which currently uses
+input compression values in the range 0 - 9. The library normally
+uses the default compression level (Z_DEFAULT_COMPRESSION = 6). Tests
+have shown that for a large majority of images, compression values in
+the range 3-6 compress nearly as well as higher levels, and do so much
+faster. For online applications it may be desirable to have maximum speed
+(Z_BEST_SPEED = 1). With versions of zlib after v0.99, you can also
+specify no compression (Z_NO_COMPRESSION = 0), but this would create
+files larger than just storing the raw bitmap. You can specify the
+compression level by calling:
+
+ #include zlib.h
+ png_set_compression_level(png_ptr, level);
+
+Another useful one is to reduce the memory level used by the library.
+The memory level defaults to 8, but it can be lowered if you are
+short on memory (running DOS, for example, where you only have 640K).
+Note that the memory level does have an effect on compression; among
+other things, lower levels will result in sections of incompressible
+data being emitted in smaller stored blocks, with a correspondingly
+larger relative overhead of up to 15% in the worst case.
+
+ #include zlib.h
+ png_set_compression_mem_level(png_ptr, level);
+
+The other functions are for configuring zlib. They are not recommended
+for normal use and may result in writing an invalid PNG file. See
+zlib.h for more information on what these mean.
+
+ #include zlib.h
+ png_set_compression_strategy(png_ptr,
+ strategy);
+
+ png_set_compression_window_bits(png_ptr,
+ window_bits);
+
+ png_set_compression_method(png_ptr, method);
+
+This controls the size of the IDAT chunks (default 8192):
+
+ png_set_compression_buffer_size(png_ptr, size);
+
+As of libpng version 1.5.4, additional APIs became
+available to set these separately for non-IDAT
+compressed chunks such as zTXt, iTXt, and iCCP:
+
+ #include zlib.h
+ #if PNG_LIBPNG_VER >= 10504
+ png_set_text_compression_level(png_ptr, level);
+
+ png_set_text_compression_mem_level(png_ptr, level);
+
+ png_set_text_compression_strategy(png_ptr,
+ strategy);
+
+ png_set_text_compression_window_bits(png_ptr,
+ window_bits);
+
+ png_set_text_compression_method(png_ptr, method);
+ #endif
+
+.SS Controlling row filtering
+
+If you want to control whether libpng uses filtering or not, which
+filters are used, and how it goes about picking row filters, you
+can call one of these functions. The selection and configuration
+of row filters can have a significant impact on the size and
+encoding speed and a somewhat lesser impact on the decoding speed
+of an image. Filtering is enabled by default for RGB and grayscale
+images (with and without alpha), but not for paletted images nor
+for any images with bit depths less than 8 bits/pixel.
+
+The 'method' parameter sets the main filtering method, which is
+currently only '0' in the PNG 1.2 specification. The 'filters'
+parameter sets which filter(s), if any, should be used for each
+scanline. Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS
+to turn filtering on and off, respectively.
+
+Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB,
+PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise
+ORed together with '|' to specify one or more filters to use.
+These filters are described in more detail in the PNG specification.
+If you intend to change the filter type during the course of writing
+the image, you should start with flags set for all of the filters
+you intend to use so that libpng can initialize its internal
+structures appropriately for all of the filter types. (Note that this
+means the first row must always be adaptively filtered, because libpng
+currently does not allocate the filter buffers until png_write_row()
+is called for the first time.)
+
+ filters = PNG_FILTER_NONE | PNG_FILTER_SUB
+ PNG_FILTER_UP | PNG_FILTER_AVG |
+ PNG_FILTER_PAETH | PNG_ALL_FILTERS;
+
+ png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE,
+ filters);
+ The second parameter can also be
+ PNG_INTRAPIXEL_DIFFERENCING if you are
+ writing a PNG to be embedded in a MNG
+ datastream. This parameter must be the
+ same as the value of filter_method used
+ in png_set_IHDR().
+
+.SS Requesting debug printout
+
+The macro definition PNG_DEBUG can be used to request debugging
+printout. Set it to an integer value in the range 0 to 3. Higher
+numbers result in increasing amounts of debugging information. The
+information is printed to the "stderr" file, unless another file
+name is specified in the PNG_DEBUG_FILE macro definition.
+
+When PNG_DEBUG > 0, the following functions (macros) become available:
+
+ png_debug(level, message)
+ png_debug1(level, message, p1)
+ png_debug2(level, message, p1, p2)
+
+in which "level" is compared to PNG_DEBUG to decide whether to print
+the message, "message" is the formatted string to be printed,
+and p1 and p2 are parameters that are to be embedded in the string
+according to printf-style formatting directives. For example,
+
+ png_debug1(2, "foo=%d", foo);
+
+is expanded to
+
+ if (PNG_DEBUG > 2)
+ fprintf(PNG_DEBUG_FILE, "foo=%d\en", foo);
+
+When PNG_DEBUG is defined but is zero, the macros aren't defined, but you
+can still use PNG_DEBUG to control your own debugging:
+
+ #ifdef PNG_DEBUG
+ fprintf(stderr, ...
+ #endif
+
+When PNG_DEBUG = 1, the macros are defined, but only png_debug statements
+having level = 0 will be printed. There aren't any such statements in
+this version of libpng, but if you insert some they will be printed.
+
+.SH VII. MNG support
+
+The MNG specification (available at http://www.libpng.org/pub/mng) allows
+certain extensions to PNG for PNG images that are embedded in MNG datastreams.
+Libpng can support some of these extensions. To enable them, use the
+png_permit_mng_features() function:
+
+ feature_set = png_permit_mng_features(png_ptr, mask)
+
+ mask is a png_uint_32 containing the bitwise OR of the
+ features you want to enable. These include
+ PNG_FLAG_MNG_EMPTY_PLTE
+ PNG_FLAG_MNG_FILTER_64
+ PNG_ALL_MNG_FEATURES
+
+ feature_set is a png_uint_32 that is the bitwise AND of
+ your mask with the set of MNG features that is
+ supported by the version of libpng that you are using.
+
+It is an error to use this function when reading or writing a standalone
+PNG file with the PNG 8-byte signature. The PNG datastream must be wrapped
+in a MNG datastream. As a minimum, it must have the MNG 8-byte signature
+and the MHDR and MEND chunks. Libpng does not provide support for these
+or any other MNG chunks; your application must provide its own support for
+them. You may wish to consider using libmng (available at
+http://www.libmng.com) instead.
+
+.SH VIII. Changes to Libpng from version 0.88
+
+It should be noted that versions of libpng later than 0.96 are not
+distributed by the original libpng author, Guy Schalnat, nor by
+Andreas Dilger, who had taken over from Guy during 1996 and 1997, and
+distributed versions 0.89 through 0.96, but rather by another member
+of the original PNG Group, Glenn Randers-Pehrson. Guy and Andreas are
+still alive and well, but they have moved on to other things.
+
+The old libpng functions png_read_init(), png_write_init(),
+png_info_init(), png_read_destroy(), and png_write_destroy() have been
+moved to PNG_INTERNAL in version 0.95 to discourage their use. These
+functions will be removed from libpng version 1.4.0.
+
+The preferred method of creating and initializing the libpng structures is
+via the png_create_read_struct(), png_create_write_struct(), and
+png_create_info_struct() because they isolate the size of the structures
+from the application, allow version error checking, and also allow the
+use of custom error handling routines during the initialization, which
+the old functions do not. The functions png_read_destroy() and
+png_write_destroy() do not actually free the memory that libpng
+allocated for these structs, but just reset the data structures, so they
+can be used instead of png_destroy_read_struct() and
+png_destroy_write_struct() if you feel there is too much system overhead
+allocating and freeing the png_struct for each image read.
+
+Setting the error callbacks via png_set_message_fn() before
+png_read_init() as was suggested in libpng-0.88 is no longer supported
+because this caused applications that do not use custom error functions
+to fail if the png_ptr was not initialized to zero. It is still possible
+to set the error callbacks AFTER png_read_init(), or to change them with
+png_set_error_fn(), which is essentially the same function, but with a new
+name to force compilation errors with applications that try to use the old
+method.
+
+Support for the sCAL, iCCP, iTXt, and sPLT chunks was added at libpng-1.0.6;
+however, iTXt support was not enabled by default.
+
+Starting with version 1.0.7, you can find out which version of the library
+you are using at run-time:
+
+ png_uint_32 libpng_vn = png_access_version_number();
+
+The number libpng_vn is constructed from the major version, minor
+version with leading zero, and release number with leading zero,
+(e.g., libpng_vn for version 1.0.7 is 10007).
+
+Note that this function does not take a png_ptr, so you can call it
+before you've created one.
+
+You can also check which version of png.h you used when compiling your
+application:
+
+ png_uint_32 application_vn = PNG_LIBPNG_VER;
+
+.SH IX. Changes to Libpng from version 1.0.x to 1.2.x
+
+Support for user memory management was enabled by default. To
+accomplish this, the functions png_create_read_struct_2(),
+png_create_write_struct_2(), png_set_mem_fn(), png_get_mem_ptr(),
+png_malloc_default(), and png_free_default() were added.
+
+Support for the iTXt chunk has been enabled by default as of
+version 1.2.41.
+
+Support for certain MNG features was enabled.
+
+Support for numbered error messages was added. However, we never got
+around to actually numbering the error messages. The function
+png_set_strip_error_numbers() was added (Note: the prototype for this
+function was inadvertently removed from png.h in PNG_NO_ASSEMBLER_CODE
+builds of libpng-1.2.15. It was restored in libpng-1.2.36).
+
+The png_malloc_warn() function was added at libpng-1.2.3. This issues
+a png_warning and returns NULL instead of aborting when it fails to
+acquire the requested memory allocation.
+
+Support for setting user limits on image width and height was enabled
+by default. The functions png_set_user_limits(), png_get_user_width_max(),
+and png_get_user_height_max() were added at libpng-1.2.6.
+
+The png_set_add_alpha() function was added at libpng-1.2.7.
+
+The function png_set_expand_gray_1_2_4_to_8() was added at libpng-1.2.9.
+Unlike png_set_gray_1_2_4_to_8(), the new function does not expand the
+tRNS chunk to alpha. The png_set_gray_1_2_4_to_8() function is
+deprecated.
+
+A number of macro definitions in support of runtime selection of
+assembler code features (especially Intel MMX code support) were
+added at libpng-1.2.0:
+
+ PNG_ASM_FLAG_MMX_SUPPORT_COMPILED
+ PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU
+ PNG_ASM_FLAG_MMX_READ_COMBINE_ROW
+ PNG_ASM_FLAG_MMX_READ_INTERLACE
+ PNG_ASM_FLAG_MMX_READ_FILTER_SUB
+ PNG_ASM_FLAG_MMX_READ_FILTER_UP
+ PNG_ASM_FLAG_MMX_READ_FILTER_AVG
+ PNG_ASM_FLAG_MMX_READ_FILTER_PAETH
+ PNG_ASM_FLAGS_INITIALIZED
+ PNG_MMX_READ_FLAGS
+ PNG_MMX_FLAGS
+ PNG_MMX_WRITE_FLAGS
+ PNG_MMX_FLAGS
+
+We added the following functions in support of runtime
+selection of assembler code features:
+
+ png_get_mmx_flagmask()
+ png_set_mmx_thresholds()
+ png_get_asm_flags()
+ png_get_mmx_bitdepth_threshold()
+ png_get_mmx_rowbytes_threshold()
+ png_set_asm_flags()
+
+We replaced all of these functions with simple stubs in libpng-1.2.20,
+when the Intel assembler code was removed due to a licensing issue.
+
+These macros are deprecated:
+
+ PNG_READ_TRANSFORMS_NOT_SUPPORTED
+ PNG_PROGRESSIVE_READ_NOT_SUPPORTED
+ PNG_NO_SEQUENTIAL_READ_SUPPORTED
+ PNG_WRITE_TRANSFORMS_NOT_SUPPORTED
+ PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED
+ PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED
+
+They have been replaced, respectively, by:
+
+ PNG_NO_READ_TRANSFORMS
+ PNG_NO_PROGRESSIVE_READ
+ PNG_NO_SEQUENTIAL_READ
+ PNG_NO_WRITE_TRANSFORMS
+ PNG_NO_READ_ANCILLARY_CHUNKS
+ PNG_NO_WRITE_ANCILLARY_CHUNKS
+
+PNG_MAX_UINT was replaced with PNG_UINT_31_MAX. It has been
+deprecated since libpng-1.0.16 and libpng-1.2.6.
+
+The function
+ png_check_sig(sig, num)
+was replaced with
+ !png_sig_cmp(sig, 0, num)
+It has been deprecated since libpng-0.90.
+
+The function
+ png_set_gray_1_2_4_to_8()
+which also expands tRNS to alpha was replaced with
+ png_set_expand_gray_1_2_4_to_8()
+which does not. It has been deprecated since libpng-1.0.18 and 1.2.9.
+
+.SH X. Changes to Libpng from version 1.0.x/1.2.x to 1.4.x
+
+Private libpng prototypes and macro definitions were moved from
+png.h and pngconf.h into a new pngpriv.h header file.
+
+Functions png_set_benign_errors(), png_benign_error(), and
+png_chunk_benign_error() were added.
+
+Support for setting the maximum amount of memory that the application
+will allocate for reading chunks was added, as a security measure.
+The functions png_set_chunk_cache_max() and png_get_chunk_cache_max()
+were added to the library.
+
+We implemented support for I/O states by adding png_ptr member io_state
+and functions png_get_io_chunk_name() and png_get_io_state() in pngget.c
+
+We added PNG_TRANSFORM_GRAY_TO_RGB to the available high-level
+input transforms.
+
+Checking for and reporting of errors in the IHDR chunk is more thorough.
+
+Support for global arrays was removed, to improve thread safety.
+
+Some obsolete/deprecated macros and functions have been removed.
+
+Typecasted NULL definitions such as
+ #define png_voidp_NULL (png_voidp)NULL
+were eliminated. If you used these in your application, just use
+NULL instead.
+
+The png_struct and info_struct members "trans" and "trans_values" were
+changed to "trans_alpha" and "trans_color", respectively.
+
+The obsolete, unused pnggccrd.c and pngvcrd.c files and related makefiles
+were removed.
+
+The PNG_1_0_X and PNG_1_2_X macros were eliminated.
+
+The PNG_LEGACY_SUPPORTED macro was eliminated.
+
+Many WIN32_WCE #ifdefs were removed.
+
+The functions png_read_init(info_ptr), png_write_init(info_ptr),
+png_info_init(info_ptr), png_read_destroy(), and png_write_destroy()
+have been removed. They have been deprecated since libpng-0.95.
+
+The png_permit_empty_plte() was removed. It has been deprecated
+since libpng-1.0.9. Use png_permit_mng_features() instead.
+
+We removed the obsolete stub functions png_get_mmx_flagmask(),
+png_set_mmx_thresholds(), png_get_asm_flags(),
+png_get_mmx_bitdepth_threshold(), png_get_mmx_rowbytes_threshold(),
+png_set_asm_flags(), and png_mmx_supported()
+
+We removed the obsolete png_check_sig(), png_memcpy_check(), and
+png_memset_check() functions. Instead use !png_sig_cmp(), memcpy(),
+and memset(), respectively.
+
+The function png_set_gray_1_2_4_to_8() was removed. It has been
+deprecated since libpng-1.0.18 and 1.2.9, when it was replaced with
+png_set_expand_gray_1_2_4_to_8() because the former function also
+expanded any tRNS chunk to an alpha channel.
+
+Macros for png_get_uint_16, png_get_uint_32, and png_get_int_32
+were added and are used by default instead of the corresponding
+functions. Unfortunately,
+from libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
+function) incorrectly returned a value of type png_uint_32.
+
+We changed the prototype for png_malloc() from
+ png_malloc(png_structp png_ptr, png_uint_32 size)
+to
+ png_malloc(png_structp png_ptr, png_alloc_size_t size)
+
+This also applies to the prototype for the user replacement malloc_fn().
+
+The png_calloc() function was added and is used in place of
+of "png_malloc(); memset();" except in the case in png_read_png()
+where the array consists of pointers; in this case a "for" loop is used
+after the png_malloc() to set the pointers to NULL, to give robust.
+behavior in case the application runs out of memory part-way through
+the process.
+
+We changed the prototypes of png_get_compression_buffer_size() and
+png_set_compression_buffer_size() to work with png_size_t instead of
+png_uint_32.
+
+Support for numbered error messages was removed by default, since we
+never got around to actually numbering the error messages. The function
+png_set_strip_error_numbers() was removed from the library by default.
+
+The png_zalloc() and png_zfree() functions are no longer exported.
+The png_zalloc() function no longer zeroes out the memory that it
+allocates. Applications that called png_zalloc(png_ptr, number, size)
+can call png_calloc(png_ptr, number*size) instead, and can call
+png_free() instead of png_zfree().
+
+Support for dithering was disabled by default in libpng-1.4.0, because
+it has not been well tested and doesn't actually "dither".
+The code was not
+removed, however, and could be enabled by building libpng with
+PNG_READ_DITHER_SUPPORTED defined. In libpng-1.4.2, this support
+was re-enabled, but the function was renamed png_set_quantize() to
+reflect more accurately what it actually does. At the same time,
+the PNG_DITHER_[RED,GREEN_BLUE]_BITS macros were also renamed to
+PNG_QUANTIZE_[RED,GREEN,BLUE]_BITS, and PNG_READ_DITHER_SUPPORTED
+was renamed to PNG_READ_QUANTIZE_SUPPORTED.
+
+We removed the trailing '.' from the warning and error messages.
+
+.SH XI. Changes to Libpng from version 1.4.x to 1.5.x
+
+From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
+function) incorrectly returned a value of type png_uint_32.
+The incorrect macro was removed from libpng-1.4.5.
+
+Checking for invalid palette index on write was added at libpng
+1.5.10. If a pixel contains an invalid (out-of-range) index libpng issues
+a benign error. This is enabled by default because this condition is an
+error according to the PNG specification, Clause 11.3.2, but the error can
+be ignored in each png_ptr with
+
+ png_set_check_for_invalid_index(png_ptr, allowed);
+
+ allowed - one of
+ 0: disable benign error (accept the
+ invalid data without warning).
+ 1: enable benign error (treat the
+ invalid data as an error or a
+ warning).
+
+If the error is ignored, or if png_benign_error() treats it as a warning,
+any invalid pixels are decoded as opaque black by the decoder and written
+as-is by the encoder.
+
+Retrieving the maximum palette index found was added at libpng-1.5.15.
+This statement must appear after png_read_png() or png_read_image() while
+reading, and after png_write_png() or png_write_image() while writing.
+
+ int max_palette = png_get_palette_max(png_ptr, info_ptr);
+
+This will return the maximum palette index found in the image, or "\-1" if
+the palette was not checked, or "0" if no palette was found. Note that this
+does not account for any palette index used by ancillary chunks such as the
+bKGD chunk; you must check those separately to determine the maximum
+palette index actually used.
+
+There are no substantial API changes between the non-deprecated parts of
+the 1.4.5 API and the 1.5.0 API; however, the ability to directly access
+members of the main libpng control structures, png_struct and png_info,
+deprecated in earlier versions of libpng, has been completely removed from
+libpng 1.5.
+
+We no longer include zlib.h in png.h. The include statement has been moved
+to pngstruct.h, where it is not accessible by applications. Applications that
+need access to information in zlib.h will need to add the '#include "zlib.h"'
+directive. It does not matter whether this is placed prior to or after
+the '"#include png.h"' directive.
+
+The png_sprintf(), png_strcpy(), and png_strncpy() macros are no longer used
+and were removed.
+
+We moved the png_strlen(), png_memcpy(), png_memset(), and png_memcmp()
+macros into a private header file (pngpriv.h) that is not accessible to
+applications.
+
+In png_get_iCCP, the type of "profile" was changed from png_charpp
+to png_bytepp, and in png_set_iCCP, from png_charp to png_const_bytep.
+
+There are changes of form in png.h, including new and changed macros to
+declare parts of the API. Some API functions with arguments that are
+pointers to data not modified within the function have been corrected to
+declare these arguments with PNG_CONST.
+
+Much of the internal use of C macros to control the library build has also
+changed and some of this is visible in the exported header files, in
+particular the use of macros to control data and API elements visible
+during application compilation may require significant revision to
+application code. (It is extremely rare for an application to do this.)
+
+Any program that compiled against libpng 1.4 and did not use deprecated
+features or access internal library structures should compile and work
+against libpng 1.5, except for the change in the prototype for
+png_get_iCCP() and png_set_iCCP() API functions mentioned above.
+
+libpng 1.5.0 adds PNG_ PASS macros to help in the reading and writing of
+interlaced images. The macros return the number of rows and columns in
+each pass and information that can be used to de-interlace and (if
+absolutely necessary) interlace an image.
+
+libpng 1.5.0 adds an API png_longjmp(png_ptr, value). This API calls
+the application-provided png_longjmp_ptr on the internal, but application
+initialized, longjmp buffer. It is provided as a convenience to avoid
+the need to use the png_jmpbuf macro, which had the unnecessary side
+effect of resetting the internal png_longjmp_ptr value.
+
+libpng 1.5.0 includes a complete fixed point API. By default this is
+present along with the corresponding floating point API. In general the
+fixed point API is faster and smaller than the floating point one because
+the PNG file format used fixed point, not floating point. This applies
+even if the library uses floating point in internal calculations. A new
+macro, PNG_FLOATING_ARITHMETIC_SUPPORTED, reveals whether the library
+uses floating point arithmetic (the default) or fixed point arithmetic
+internally for performance critical calculations such as gamma correction.
+In some cases, the gamma calculations may produce slightly different
+results. This has changed the results in png_rgb_to_gray and in alpha
+composition (png_set_background for example). This applies even if the
+original image was already linear (gamma == 1.0) and, therefore, it is
+not necessary to linearize the image. This is because libpng has *not*
+been changed to optimize that case correctly, yet.
+
+Fixed point support for the sCAL chunk comes with an important caveat;
+the sCAL specification uses a decimal encoding of floating point values
+and the accuracy of PNG fixed point values is insufficient for
+representation of these values. Consequently a "string" API
+(png_get_sCAL_s and png_set_sCAL_s) is the only reliable way of reading
+arbitrary sCAL chunks in the absence of either the floating point API or
+internal floating point calculations. Starting with libpng-1.5.0, both
+of these functions are present when PNG_sCAL_SUPPORTED is defined. Prior
+to libpng-1.5.0, their presence also depended upon PNG_FIXED_POINT_SUPPORTED
+being defined and PNG_FLOATING_POINT_SUPPORTED not being defined.
+
+Applications no longer need to include the optional distribution header
+file pngusr.h or define the corresponding macros during application
+build in order to see the correct variant of the libpng API. From 1.5.0
+application code can check for the corresponding _SUPPORTED macro:
+
+#ifdef PNG_INCH_CONVERSIONS_SUPPORTED
+ /* code that uses the inch conversion APIs. */
+#endif
+
+This macro will only be defined if the inch conversion functions have been
+compiled into libpng. The full set of macros, and whether or not support
+has been compiled in, are available in the header file pnglibconf.h.
+This header file is specific to the libpng build. Notice that prior to
+1.5.0 the _SUPPORTED macros would always have the default definition unless
+reset by pngusr.h or by explicit settings on the compiler command line.
+These settings may produce compiler warnings or errors in 1.5.0 because
+of macro redefinition.
+
+Applications can now choose whether to use these macros or to call the
+corresponding function by defining PNG_USE_READ_MACROS or
+PNG_NO_USE_READ_MACROS before including png.h. Notice that this is
+only supported from 1.5.0; defining PNG_NO_USE_READ_MACROS prior to 1.5.0
+will lead to a link failure.
+
+Prior to libpng-1.5.4, the zlib compressor used the same set of parameters
+when compressing the IDAT data and textual data such as zTXt and iCCP.
+In libpng-1.5.4 we reinitialized the zlib stream for each type of data.
+We added five png_set_text_*() functions for setting the parameters to
+use with textual data.
+
+Prior to libpng-1.5.4, the PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
+option was off by default, and slightly inaccurate scaling occurred.
+This option can no longer be turned off, and the choice of accurate
+or inaccurate 16-to-8 scaling is by using the new png_set_scale_16_to_8()
+API for accurate scaling or the old png_set_strip_16_to_8() API for simple
+chopping. In libpng-1.5.4, the PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
+macro became PNG_READ_SCALE_16_TO_8_SUPPORTED, and the PNG_READ_16_TO_8
+macro became PNG_READ_STRIP_16_TO_8_SUPPORTED, to enable the two
+png_set_*_16_to_8() functions separately.
+
+Prior to libpng-1.5.4, the png_set_user_limits() function could only be
+used to reduce the width and height limits from the value of
+PNG_USER_WIDTH_MAX and PNG_USER_HEIGHT_MAX, although this document said
+that it could be used to override them. Now this function will reduce or
+increase the limits.
+
+Starting in libpng-1.5.10, the user limits can be set en masse with the
+configuration option PNG_SAFE_LIMITS_SUPPORTED. If this option is enabled,
+a set of "safe" limits is applied in pngpriv.h. These can be overridden by
+application calls to png_set_user_limits(), png_set_user_chunk_cache_max(),
+and/or png_set_user_malloc_max() that increase or decrease the limits. Also,
+in libpng-1.5.10 the default width and height limits were increased
+from 1,000,000 to 0x7fffffff (i.e., made unlimited). Therefore, the
+limits are now
+ default safe
+ png_user_width_max 0x7fffffff 1,000,000
+ png_user_height_max 0x7fffffff 1,000,000
+ png_user_chunk_cache_max 0 (unlimited) 128
+ png_user_chunk_malloc_max 0 (unlimited) 8,000,000
+
+The png_set_option() function (and the "options" member of the png struct) was
+added to libpng-1.5.15, with option PNG_ARM_NEON.
+
+The library now supports a complete fixed point implementation and can
+thus be used on systems that have no floating point support or very
+limited or slow support. Previously gamma correction, an essential part
+of complete PNG support, required reasonably fast floating point.
+
+As part of this the choice of internal implementation has been made
+independent of the choice of fixed versus floating point APIs and all the
+missing fixed point APIs have been implemented.
+
+The exact mechanism used to control attributes of API functions has
+changed, as described in the INSTALL file.
+
+A new test program, pngvalid, is provided in addition to pngtest.
+pngvalid validates the arithmetic accuracy of the gamma correction
+calculations and includes a number of validations of the file format.
+A subset of the full range of tests is run when "make check" is done
+(in the 'configure' build.) pngvalid also allows total allocated memory
+usage to be evaluated and performs additional memory overwrite validation.
+
+Many changes to individual feature macros have been made. The following
+are the changes most likely to be noticed by library builders who
+configure libpng:
+
+1) All feature macros now have consistent naming:
+
+#define PNG_NO_feature turns the feature off
+#define PNG_feature_SUPPORTED turns the feature on
+
+pnglibconf.h contains one line for each feature macro which is either:
+
+#define PNG_feature_SUPPORTED
+
+if the feature is supported or:
+
+/*#undef PNG_feature_SUPPORTED*/
+
+if it is not. Library code consistently checks for the 'SUPPORTED' macro.
+It does not, and libpng applications should not, check for the 'NO' macro
+which will not normally be defined even if the feature is not supported.
+The 'NO' macros are only used internally for setting or not setting the
+corresponding 'SUPPORTED' macros.
+
+Compatibility with the old names is provided as follows:
+
+PNG_INCH_CONVERSIONS turns on PNG_INCH_CONVERSIONS_SUPPORTED
+
+And the following definitions disable the corresponding feature:
+
+PNG_SETJMP_NOT_SUPPORTED disables SETJMP
+PNG_READ_TRANSFORMS_NOT_SUPPORTED disables READ_TRANSFORMS
+PNG_NO_READ_COMPOSITED_NODIV disables READ_COMPOSITE_NODIV
+PNG_WRITE_TRANSFORMS_NOT_SUPPORTED disables WRITE_TRANSFORMS
+PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED disables READ_ANCILLARY_CHUNKS
+PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED disables WRITE_ANCILLARY_CHUNKS
+
+Library builders should remove use of the above, inconsistent, names.
+
+2) Warning and error message formatting was previously conditional on
+the STDIO feature. The library has been changed to use the
+CONSOLE_IO feature instead. This means that if CONSOLE_IO is disabled
+the library no longer uses the printf(3) functions, even though the
+default read/write implementations use (FILE) style stdio.h functions.
+
+3) Three feature macros now control the fixed/floating point decisions:
+
+PNG_FLOATING_POINT_SUPPORTED enables the floating point APIs
+
+PNG_FIXED_POINT_SUPPORTED enables the fixed point APIs; however, in
+practice these are normally required internally anyway (because the PNG
+file format is fixed point), therefore in most cases PNG_NO_FIXED_POINT
+merely stops the function from being exported.
+
+PNG_FLOATING_ARITHMETIC_SUPPORTED chooses between the internal floating
+point implementation or the fixed point one. Typically the fixed point
+implementation is larger and slower than the floating point implementation
+on a system that supports floating point; however, it may be faster on a
+system which lacks floating point hardware and therefore uses a software
+emulation.
+
+4) Added PNG_{READ,WRITE}_INT_FUNCTIONS_SUPPORTED. This allows the
+functions to read and write ints to be disabled independently of
+PNG_USE_READ_MACROS, which allows libpng to be built with the functions
+even though the default is to use the macros - this allows applications
+to choose at app buildtime whether or not to use macros (previously
+impossible because the functions weren't in the default build.)
+
+.SH XII. Changes to Libpng from version 1.5.x to 1.6.x
+
+A "simplified API" has been added (see documentation in png.h and a simple
+example in contrib/examples/pngtopng.c). The new publicly visible API
+includes the following:
+
+ macros:
+ PNG_FORMAT_*
+ PNG_IMAGE_*
+ structures:
+ png_control
+ png_image
+ read functions
+ png_image_begin_read_from_file()
+ png_image_begin_read_from_stdio()
+ png_image_begin_read_from_memory()
+ png_image_finish_read()
+ png_image_free()
+ write functions
+ png_image_write_to_file()
+ png_image_write_to_stdio()
+
+Starting with libpng-1.6.0, you can configure libpng to prefix all exported
+symbols, using the PNG_PREFIX macro.
+
+We no longer include string.h in png.h. The include statement has been moved
+to pngpriv.h, where it is not accessible by applications. Applications that
+need access to information in string.h must add an '#include <string.h>'
+directive. It does not matter whether this is placed prior to or after
+the '#include "png.h"' directive.
+
+The following API are now DEPRECATED:
+ png_info_init_3()
+ png_convert_to_rfc1123() which has been replaced
+ with png_convert_to_rfc1123_buffer()
+ png_malloc_default()
+ png_free_default()
+ png_reset_zstream()
+
+The following have been removed:
+ png_get_io_chunk_name(), which has been replaced
+ with png_get_io_chunk_type(). The new
+ function returns a 32-bit integer instead of
+ a string.
+ The png_sizeof(), png_strlen(), png_memcpy(), png_memcmp(), and
+ png_memset() macros are no longer used in the libpng sources and
+ have been removed. These had already been made invisible to applications
+ (i.e., defined in the private pngpriv.h header file) since libpng-1.5.0.
+
+The signatures of many exported functions were changed, such that
+ png_structp became png_structrp or png_const_structrp
+ png_infop became png_inforp or png_const_inforp
+where "rp" indicates a "restricted pointer".
+
+Dropped support for 16-bit platforms. The support for FAR/far types has
+been eliminated and the definition of png_alloc_size_t is now controlled
+by a flag so that 'small size_t' systems can select it if necessary.
+
+Error detection in some chunks has improved; in particular the iCCP chunk
+reader now does pretty complete validation of the basic format. Some bad
+profiles that were previously accepted are now accepted with a warning or
+rejected, depending upon the png_set_benign_errors() setting, in particular
+the very old broken Microsoft/HP 3144-byte sRGB profile. Starting with
+libpng-1.6.11, recognizing and checking sRGB profiles can be avoided by
+means of
+
+ #if defined(PNG_SKIP_sRGB_CHECK_PROFILE) && \
+ defined(PNG_SET_OPTION_SUPPORTED)
+ png_set_option(png_ptr, PNG_SKIP_sRGB_CHECK_PROFILE,
+ PNG_OPTION_ON);
+ #endif
+
+It's not a good idea to do this if you are using the "simplified API",
+which needs to be able to recognize sRGB profiles conveyed via the iCCP
+chunk.
+
+The PNG spec requirement that only grayscale profiles may appear in images
+with color type 0 or 4 and that even if the image only contains gray pixels,
+only RGB profiles may appear in images with color type 2, 3, or 6, is now
+enforced. The sRGB chunk is allowed to appear in images with any color type
+and is interpreted by libpng to convey a one-tracer-curve gray profile or a
+three-tracer-curve RGB profile as appropriate.
+
+Prior to libpng-1.6.0 a warning would be issued if the iTXt chunk contained
+an empty language field or an empty translated keyword. Both of these
+are allowed by the PNG specification, so these warnings are no longer issued.
+
+The library now issues an error if the application attempts to set a
+transform after it calls png_read_update_info() or if it attempts to call
+both png_read_update_info() and png_start_read_image() or to call either
+of them more than once.
+
+The default condition for benign_errors is now to treat benign errors as
+warnings while reading and as errors while writing.
+
+The library now issues a warning if both background processing and RGB to
+gray are used when gamma correction happens. As with previous versions of
+the library the results are numerically very incorrect in this case.
+
+There are some minor arithmetic changes in some transforms such as
+png_set_background(), that might be detected by certain regression tests.
+
+Unknown chunk handling has been improved internally, without any API change.
+This adds more correct option control of the unknown handling, corrects
+a pre-existing bug where the per-chunk 'keep' setting is ignored, and makes
+it possible to skip IDAT chunks in the sequential reader.
+
+The machine-generated configure files are no longer included in branches
+libpng16 and later of the GIT repository. They continue to be included
+in the tarball releases, however.
+
+Libpng-1.6.0 through 1.6.2 used the CMF bytes at the beginning of the IDAT
+stream to set the size of the sliding window for reading instead of using the
+default 32-kbyte sliding window size. It was discovered that there are
+hundreds of PNG files in the wild that have incorrect CMF bytes that caused
+zlib to issue the "invalid distance too far back" error and reject the file.
+Libpng-1.6.3 and later calculate their own safe CMF from the image dimensions,
+provide a way to revert to the libpng-1.5.x behavior (ignoring the CMF bytes
+and using a 32-kbyte sliding window), by using
+
+ png_set_option(png_ptr, PNG_MAXIMUM_INFLATE_WINDOW,
+ PNG_OPTION_ON);
+
+and provide a tool (contrib/tools/pngfix) for rewriting a PNG file while
+optimizing the CMF bytes in its IDAT chunk correctly.
+
+Libpng-1.6.0 and libpng-1.6.1 wrote uncompressed iTXt chunks with the wrong
+length, which resulted in PNG files that cannot be read beyond the bad iTXt
+chunk. This error was fixed in libpng-1.6.3, and a tool (called
+contrib/tools/png-fix-itxt) has been added to the libpng distribution.
+
+Starting with libpng-1.6.17, the PNG_SAFE_LIMITS macro was eliminated
+and safe limits are used by default (users who need larger limits
+can still override them at compile time or run time, as described above).
+
+The new limits are
+ default spec limit
+ png_user_width_max 1,000,000 2,147,483,647
+ png_user_height_max 1,000,000 2,147,483,647
+ png_user_chunk_cache_max 128 unlimited
+ png_user_chunk_malloc_max 8,000,000 unlimited
+
+Starting with libpng-1.6.18, a PNG_RELEASE_BUILD macro was added, which allows
+library builders to control compilation for an installed system (a release build).
+It can be set for testing debug or beta builds to ensure that they will compile
+when the build type is switched to RC or STABLE. In essence this overrides the
+PNG_LIBPNG_BUILD_BASE_TYPE definition which is not directly user controllable.
+
+Starting with libpng-1.6.19, attempting to set an over-length PLTE chunk
+is an error. Previously this requirement of the PNG specification was not
+enforced, and the palette was always limited to 256 entries. An over-length
+PLTE chunk found in an input PNG is silently truncated.
+
+.SH XIII. Detecting libpng
+
+The png_get_io_ptr() function has been present since libpng-0.88, has never
+changed, and is unaffected by conditional compilation macros. It is the
+best choice for use in configure scripts for detecting the presence of any
+libpng version since 0.88. In an autoconf "configure.in" you could use
+
+ AC_CHECK_LIB(png, png_get_io_ptr, ...
+
+.SH XV. Source code repository
+
+Since about February 2009, version 1.2.34, libpng has been under "git" source
+control. The git repository was built from old libpng-x.y.z.tar.gz files
+going back to version 0.70. You can access the git repository (read only)
+at
+
+ git://git.code.sf.net/p/libpng/code
+
+or you can browse it with a web browser by selecting the "code" button at
+
+ https://sourceforge.net/projects/libpng
+
+Patches can be sent to glennrp at users.sourceforge.net or to
+png-mng-implement at lists.sourceforge.net or you can upload them to
+the libpng bug tracker at
+
+ http://libpng.sourceforge.net
+
+We also accept patches built from the tar or zip distributions, and
+simple verbal discriptions of bug fixes, reported either to the
+SourceForge bug tracker, to the png-mng-implement at lists.sf.net
+mailing list, or directly to glennrp.
+
+.SH XV. Coding style
+
+Our coding style is similar to the "Allman" style
+(See http://en.wikipedia.org/wiki/Indent_style#Allman_style), with curly
+braces on separate lines:
+
+ if (condition)
+ {
+ action;
+ }
+
+ else if (another condition)
+ {
+ another action;
+ }
+
+The braces can be omitted from simple one-line actions:
+
+ if (condition)
+ return (0);
+
+We use 3-space indentation, except for continued statements which
+are usually indented the same as the first line of the statement
+plus four more spaces.
+
+For macro definitions we use 2-space indentation, always leaving the "#"
+in the first column.
+
+ #ifndef PNG_NO_FEATURE
+ # ifndef PNG_FEATURE_SUPPORTED
+ # define PNG_FEATURE_SUPPORTED
+ # endif
+ #endif
+
+Comments appear with the leading "/*" at the same indentation as
+the statement that follows the comment:
+
+ /* Single-line comment */
+ statement;
+
+ /* This is a multiple-line
+ * comment.
+ */
+ statement;
+
+Very short comments can be placed after the end of the statement
+to which they pertain:
+
+ statement; /* comment */
+
+We don't use C++ style ("//") comments. We have, however,
+used them in the past in some now-abandoned MMX assembler
+code.
+
+Functions and their curly braces are not indented, and
+exported functions are marked with PNGAPI:
+
+ /* This is a public function that is visible to
+ * application programmers. It does thus-and-so.
+ */
+ void PNGAPI
+ png_exported_function(png_ptr, png_info, foo)
+ {
+ body;
+ }
+
+The return type and decorations are placed on a separate line
+ahead of the function name, as illustrated above.
+
+The prototypes for all exported functions appear in png.h,
+above the comment that says
+
+ /* Maintainer: Put new public prototypes here ... */
+
+We mark all non-exported functions with "/* PRIVATE */"":
+
+ void /* PRIVATE */
+ png_non_exported_function(png_ptr, png_info, foo)
+ {
+ body;
+ }
+
+The prototypes for non-exported functions (except for those in
+pngtest) appear in pngpriv.h above the comment that says
+
+ /* Maintainer: Put new private prototypes here ^ */
+
+To avoid polluting the global namespace, the names of all exported
+functions and variables begin with "png_", and all publicly visible C
+preprocessor macros begin with "PNG". We request that applications that
+use libpng *not* begin any of their own symbols with either of these strings.
+
+We put a space after the "sizeof" operator and we omit the
+optional parentheses around its argument when the argument
+is an expression, not a type name, and we always enclose the
+sizeof operator, with its argument, in parentheses:
+
+ (sizeof (png_uint_32))
+ (sizeof array)
+
+Prior to libpng-1.6.0 we used a "png_sizeof()" macro, formatted as
+though it were a function.
+
+Control keywords if, for, while, and switch are always followed by a space
+to distinguish them from function calls, which have no trailing space.
+
+We put a space after each comma and after each semicolon
+in "for" statements, and we put spaces before and after each
+C binary operator and after "for" or "while", and before
+"?". We don't put a space between a typecast and the expression
+being cast, nor do we put one between a function name and the
+left parenthesis that follows it:
+
+ for (i = 2; i > 0; \-\-i)
+ y[i] = a(x) + (int)b;
+
+We prefer #ifdef and #ifndef to #if defined() and #if !defined()
+when there is only one macro being tested. We always use parentheses
+with "defined".
+
+We express integer constants that are used as bit masks in hex format,
+with an even number of lower-case hex digits, and to make them unsigned
+(e.g., 0x00U, 0xffU, 0x0100U) and long if they are greater than 0x7fff
+(e.g., 0xffffUL).
+
+We prefer to use underscores rather than camelCase in names, except
+for a few type names that we inherit from zlib.h.
+
+We prefer "if (something != 0)" and "if (something == 0)"
+over "if (something)" and if "(!something)", respectively.
+
+We do not use the TAB character for indentation in the C sources.
+
+Lines do not exceed 80 characters.
+
+Other rules can be inferred by inspecting the libpng source.
+
+.SH XVI. Y2K Compliance in libpng
+
+Since the PNG Development group is an ad-hoc body, we can't make
+an official declaration.
+
+This is your unofficial assurance that libpng from version 0.71 and
+upward through 1.6.20 are Y2K compliant. It is my belief that earlier
+versions were also Y2K compliant.
+
+Libpng only has two year fields. One is a 2-byte unsigned integer
+that will hold years up to 65535. The other, which is deprecated,
+holds the date in text format, and will hold years up to 9999.
+
+The integer is
+ "png_uint_16 year" in png_time_struct.
+
+The string is
+ "char time_buffer[29]" in png_struct. This is no longer used
+in libpng-1.6.x and will be removed from libpng-1.7.0.
+
+There are seven time-related functions:
+
+ png_convert_to_rfc_1123_buffer() in png.c
+ (formerly png_convert_to_rfc_1152() in error, and
+ also formerly png_convert_to_rfc_1123())
+ png_convert_from_struct_tm() in pngwrite.c, called
+ in pngwrite.c
+ png_convert_from_time_t() in pngwrite.c
+ png_get_tIME() in pngget.c
+ png_handle_tIME() in pngrutil.c, called in pngread.c
+ png_set_tIME() in pngset.c
+ png_write_tIME() in pngwutil.c, called in pngwrite.c
+
+All appear to handle dates properly in a Y2K environment. The
+png_convert_from_time_t() function calls gmtime() to convert from system
+clock time, which returns (year - 1900), which we properly convert to
+the full 4-digit year. There is a possibility that applications using
+libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
+function, or that they are incorrectly passing only a 2-digit year
+instead of "year - 1900" into the png_convert_from_struct_tm() function,
+but this is not under our control. The libpng documentation has always
+stated that it works with 4-digit years, and the APIs have been
+documented as such.
+
+The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned
+integer to hold the year, and can hold years as large as 65535.
+
+zlib, upon which libpng depends, is also Y2K compliant. It contains
+no date-related code.
+
+
+ Glenn Randers-Pehrson
+ libpng maintainer
+ PNG Development Group
+
+.SH NOTE
+
+Note about libpng version numbers:
+
+Due to various miscommunications, unforeseen code incompatibilities
+and occasional factors outside the authors' control, version numbering
+on the library has not always been consistent and straightforward.
+The following table summarizes matters since version 0.89c, which was
+the first widely used release:
+
+ source png.h png.h shared-lib
+ version string int version
+ ------- ------ ----- ----------
+ 0.89c "1.0 beta 3" 0.89 89 1.0.89
+ 0.90 "1.0 beta 4" 0.90 90 0.90 [should have been 2.0.90]
+ 0.95 "1.0 beta 5" 0.95 95 0.95 [should have been 2.0.95]
+ 0.96 "1.0 beta 6" 0.96 96 0.96 [should have been 2.0.96]
+ 0.97b "1.00.97 beta 7" 1.00.97 97 1.0.1 [should have been 2.0.97]
+ 0.97c 0.97 97 2.0.97
+ 0.98 0.98 98 2.0.98
+ 0.99 0.99 98 2.0.99
+ 0.99a-m 0.99 99 2.0.99
+ 1.00 1.00 100 2.1.0 [100 should be 10000]
+ 1.0.0 (from here on, the 100 2.1.0 [100 should be 10000]
+ 1.0.1 png.h string is 10001 2.1.0
+ 1.0.1a-e identical to the 10002 from here on, the shared library
+ 1.0.2 source version) 10002 is 2.V where V is the source code
+ 1.0.2a-b 10003 version, except as noted.
+ 1.0.3 10003
+ 1.0.3a-d 10004
+ 1.0.4 10004
+ 1.0.4a-f 10005
+ 1.0.5 (+ 2 patches) 10005
+ 1.0.5a-d 10006
+ 1.0.5e-r 10100 (not source compatible)
+ 1.0.5s-v 10006 (not binary compatible)
+ 1.0.6 (+ 3 patches) 10006 (still binary incompatible)
+ 1.0.6d-f 10007 (still binary incompatible)
+ 1.0.6g 10007
+ 1.0.6h 10007 10.6h (testing xy.z so-numbering)
+ 1.0.6i 10007 10.6i
+ 1.0.6j 10007 2.1.0.6j (incompatible with 1.0.0)
+ 1.0.7beta11-14 DLLNUM 10007 2.1.0.7beta11-14 (binary compatible)
+ 1.0.7beta15-18 1 10007 2.1.0.7beta15-18 (binary compatible)
+ 1.0.7rc1-2 1 10007 2.1.0.7rc1-2 (binary compatible)
+ 1.0.7 1 10007 (still compatible)
+ ...
+ 1.0.19 10 10019 10.so.0.19[.0]
+ ...
+ 1.2.53 13 10253 12.so.0.53[.0]
+ ...
+ 1.5.23 15 10523 15.so.15.23[.0]
+ ...
+ 1.6.20 16 10620 16.so.16.20[.0]
+
+Henceforth the source version will match the shared-library minor
+and patch numbers; the shared-library major version number will be
+used for changes in backward compatibility, as it is intended. The
+PNG_PNGLIB_VER macro, which is not used within libpng but is available
+for applications, is an unsigned integer of the form xyyzz corresponding
+to the source version x.y.z (leading zeros in y and z). Beta versions
+were given the previous public release number plus a letter, until
+version 1.0.6j; from then on they were given the upcoming public
+release number plus "betaNN" or "rcNN".
+
+.SH "SEE ALSO"
+.IR libpngpf(3) ", " png(5)
+.LP
+.IR libpng :
+.IP
+http://libpng.sourceforge.net (follow the [DOWNLOAD] link)
+http://www.libpng.org/pub/png
+
+.LP
+.IR zlib :
+.IP
+(generally) at the same location as
+.I libpng
+or at
+.br
+ftp://ftp.info-zip.org/pub/infozip/zlib
+
+.LP
+.IR PNG specification: RFC 2083
+.IP
+(generally) at the same location as
+.I libpng
+or at
+.br
+ftp://ftp.rfc-editor.org:/in-notes/rfc2083.txt
+.br
+or (as a W3C Recommendation) at
+.br
+http://www.w3.org/TR/REC-png.html
+
+.LP
+In the case of any inconsistency between the PNG specification
+and this library, the specification takes precedence.
+
+.SH AUTHORS
+This man page: Glenn Randers-Pehrson
+<glennrp at users.sourceforge.net>
+
+The contributing authors would like to thank all those who helped
+with testing, bug fixes, and patience. This wouldn't have been
+possible without all of you.
+
+Thanks to Frank J. T. Wojcik for helping with the documentation.
+
+Libpng version 1.6.20 - December 3, 2015:
+Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
+Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
+
+Supported by the PNG development group
+.br
+png-mng-implement at lists.sf.net
+(subscription required; visit
+png-mng-implement at lists.sourceforge.net (subscription required; visit
+https://lists.sourceforge.net/lists/listinfo/png-mng-implement
+to subscribe).
+
+.SH NOTICES:
+
+This copy of the libpng notices is provided for your convenience. In case of
+any discrepancy between this copy and the notices in the file png.h that is
+included in the libpng distribution, the latter shall prevail.
+
+COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
+
+If you modify libpng you may insert additional notices immediately following
+this sentence.
+
+This code is released under the libpng license.
+
+libpng versions 1.0.7, July 1, 2000, through 1.6.20, December 3, 2015, are
+Copyright (c) 2000-2002, 2004, 2006-2015 Glenn Randers-Pehrson, are
+derived from libpng-1.0.6, and are distributed according to the same
+disclaimer and license as libpng-1.0.6 with the following individuals
+added to the list of Contributing Authors:
+
+ Simon-Pierre Cadieux
+ Eric S. Raymond
+ Mans Rullgard
+ Cosmin Truta
+ Gilles Vollant
+ James Yu
+
+and with the following additions to the disclaimer:
+
+ There is no warranty against interference with your enjoyment of the
+ library or against infringement. There is no warranty that our
+ efforts or the library will fulfill any of your particular purposes
+ or needs. This library is provided with all faults, and the entire
+ risk of satisfactory quality, performance, accuracy, and effort is with
+ the user.
+
+libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
+Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
+libpng-0.96, and are distributed according to the same disclaimer and
+license as libpng-0.96, with the following individuals added to the list
+of Contributing Authors:
+
+ Tom Lane
+ Glenn Randers-Pehrson
+ Willem van Schaik
+
+libpng versions 0.89, June 1996, through 0.96, May 1997, are
+Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,
+and are distributed according to the same disclaimer and license as
+libpng-0.88, with the following individuals added to the list of
+Contributing Authors:
+
+ John Bowler
+ Kevin Bracey
+ Sam Bushell
+ Magnus Holmgren
+ Greg Roelofs
+ Tom Tanner
+
+libpng versions 0.5, May 1995, through 0.88, January 1996, are
+Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
+
+For the purposes of this copyright and license, "Contributing Authors"
+is defined as the following set of individuals:
+
+ Andreas Dilger
+ Dave Martindale
+ Guy Eric Schalnat
+ Paul Schmidt
+ Tim Wegner
+
+The PNG Reference Library is supplied "AS IS". The Contributing Authors
+and Group 42, Inc. disclaim all warranties, expressed or implied,
+including, without limitation, the warranties of merchantability and of
+fitness for any purpose. The Contributing Authors and Group 42, Inc.
+assume no liability for direct, indirect, incidental, special, exemplary,
+or consequential damages, which may result from the use of the PNG
+Reference Library, even if advised of the possibility of such damage.
+
+Permission is hereby granted to use, copy, modify, and distribute this
+source code, or portions hereof, for any purpose, without fee, subject
+to the following restrictions:
+
+ 1. The origin of this source code must not be misrepresented.
+
+ 2. Altered versions must be plainly marked as such and must not
+ be misrepresented as being the original source.
+
+ 3. This Copyright notice may not be removed or altered from any
+ source or altered source distribution.
+
+The Contributing Authors and Group 42, Inc. specifically permit, without
+fee, and encourage the use of this source code as a component to
+supporting the PNG file format in commercial products. If you use this
+source code in a product, acknowledgment is not required but would be
+appreciated.
+
+END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.
+
+A "png_get_copyright" function is available, for convenient use in "about"
+boxes and the like:
+
+ printf("%s", png_get_copyright(NULL));
+
+Also, the PNG logo (in PNG format, of course) is supplied in the
+files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
+
+Libpng is OSI Certified Open Source Software. OSI Certified Open Source is
+a certification mark of the Open Source Initiative. OSI has not addressed
+the additional disclaimers inserted at version 1.0.7.
+
+Glenn Randers-Pehrson
+glennrp at users.sourceforge.net
+December 3, 2015
+
+.\" end of man page
+
diff --git a/libpng/libpng.pc.in b/libpng/libpng.pc.in
new file mode 100644
index 0000000..3e7e2c5
--- /dev/null
+++ b/libpng/libpng.pc.in
@@ -0,0 +1,11 @@
+prefix=@prefix@
+exec_prefix=@exec_prefix@
+libdir=@libdir@
+includedir=@includedir@/libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@
+
+Name: libpng
+Description: Loads and saves PNG files
+Version: @PNGLIB_VERSION@
+Libs: -L${libdir} -lpng@PNGLIB_MAJOR@@PNGLIB_MINOR@
+Libs.private: @LIBS@
+Cflags: -I${includedir}
diff --git a/libpng/libpngpf.3 b/libpng/libpngpf.3
new file mode 100644
index 0000000..4da0843
--- /dev/null
+++ b/libpng/libpngpf.3
@@ -0,0 +1,18 @@
+.TH LIBPNGPF 3 "December 3, 2015"
+.SH NAME
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.20
+(private functions)
+.SH SYNOPSIS
+\fB#include \fI"pngpriv.h"
+
+\fBAs of libpng version \fP\fI1.5.1\fP\fB, this section is no longer \fP\fImaintained\fP\fB, now that the private function prototypes are hidden in pngpriv.h and not accessible to applications. Look in pngpriv.h for the prototypes and a short description of each \fIfunction.
+
+.SH DESCRIPTION
+The functions previously listed here are used privately by libpng and are not
+available for use by applications. They are not "exported" to applications
+using shared libraries.
+
+.SH SEE ALSO
+.BR "png"(5), " libpng"(3), " zlib"(3), " deflate"(5), " " and " zlib"(5)
+.SH AUTHOR
+Glenn Randers-Pehrson
diff --git a/libpng/png.5 b/libpng/png.5
new file mode 100644
index 0000000..76a327b
--- /dev/null
+++ b/libpng/png.5
@@ -0,0 +1,74 @@
+.TH PNG 5 "December 3, 2015"
+.SH NAME
+png \- Portable Network Graphics (PNG) format
+.SH DESCRIPTION
+PNG (Portable Network Graphics) is an extensible file format for the
+lossless, portable, well-compressed storage of raster images. PNG provides
+a patent-free replacement for GIF and can also replace many
+common uses of TIFF. Indexed-color, grayscale, and truecolor images are
+supported, plus an optional alpha channel. Sample depths range from
+1 to 16 bits.
+.br
+
+PNG is designed to work well in online viewing applications, such as the
+World Wide Web, so it is fully streamable with a progressive display
+option. PNG is robust, providing both full file integrity checking and
+fast, simple detection of common transmission errors. Also, PNG can store
+gamma and chromaticity data for improved color matching on heterogeneous
+platforms.
+
+.SH "SEE ALSO"
+.BR "libpng"(3), " libpngpf"(3), " zlib"(3), " deflate"(5), " " and " zlib"(5)
+.LP
+PNG specification (second edition), November 2003:
+.IP
+.br
+ <http://www.w3.org/TR/2003/REC-PNG-20031110/
+PNG 1.2 specification, July 1999:
+.IP
+.br
+http://png-mng.sourceforge.net/pub/png/spec/1.2/
+.LP
+PNG 1.0 specification, October 1996:
+.IP
+.br
+RFC 2083
+.IP
+.br
+ftp://ds.internic.net/rfc/rfc2083.txt
+.br
+or (as a W3C Recommendation) at
+.br
+http://www.w3.org/TR/REC-png-961001
+.SH AUTHORS
+This man page: Glenn Randers-Pehrson
+.LP
+Portable Network Graphics (PNG) Specification (Second Edition)
+Information technology - Computer graphics and image processing -
+Portable Network Graphics (PNG): Functional specification.
+ISO/IEC 15948:2003 (E) (November 10, 2003): David Duce and others.
+.LP
+Portable Network Graphics (PNG) Specification Version 1.2 (July 8, 1999):
+Glenn Randers-Pehrson and others (png-list).
+.LP
+Portable Network Graphics (PNG) Specification Version 1.0 (October 1, 1996):
+Thomas Boutell and others (png-list).
+.LP
+
+
+.SH COPYRIGHT NOTICE
+.LP
+This man page is Copyright (c) 1998-2006 Glenn Randers-Pehrson. See png.h
+for conditions of use and distribution.
+.LP
+The PNG Specification (Second Edition) is
+Copyright (c) 2003 W3C. (MIT, ERCIM, Keio), All Rights Reserved.
+.LP
+The PNG-1.2 specification is copyright (c) 1999 Glenn Randers-Pehrson.
+See the specification for conditions of use and distribution.
+.LP
+The PNG-1.0 specification is copyright (c) 1996 Massachusetts Institute of
+Technology. See the specification for conditions of use and distribution.
+.LP
+.\" end of man page
+
diff --git a/libpng/png.c b/libpng/png.c
new file mode 100644
index 0000000..c183e3f
--- /dev/null
+++ b/libpng/png.c
@@ -0,0 +1,4498 @@
+
+/* png.c - location for general purpose libpng functions
+ *
+ * Last changed in libpng 1.6.19 [November 12, 2015]
+ * Copyright (c) 1998-2015 Glenn Randers-Pehrson
+ * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ */
+
+#include "pngpriv.h"
+
+/* Generate a compiler error if there is an old png.h in the search path. */
+typedef png_libpng_version_1_6_20 Your_png_h_is_not_version_1_6_20;
+
+/* Tells libpng that we have already handled the first "num_bytes" bytes
+ * of the PNG file signature. If the PNG data is embedded into another
+ * stream we can set num_bytes = 8 so that libpng will not attempt to read
+ * or write any of the magic bytes before it starts on the IHDR.
+ */
+
+#ifdef PNG_READ_SUPPORTED
+void PNGAPI
+png_set_sig_bytes(png_structrp png_ptr, int num_bytes)
+{
+ unsigned int nb = (unsigned int)num_bytes;
+
+ png_debug(1, "in png_set_sig_bytes");
+
+ if (png_ptr == NULL)
+ return;
+
+ if (num_bytes < 0)
+ nb = 0;
+
+ if (nb > 8)
+ png_error(png_ptr, "Too many bytes for PNG signature");
+
+ png_ptr->sig_bytes = (png_byte)nb;
+}
+
+/* Checks whether the supplied bytes match the PNG signature. We allow
+ * checking less than the full 8-byte signature so that those apps that
+ * already read the first few bytes of a file to determine the file type
+ * can simply check the remaining bytes for extra assurance. Returns
+ * an integer less than, equal to, or greater than zero if sig is found,
+ * respectively, to be less than, to match, or be greater than the correct
+ * PNG signature (this is the same behavior as strcmp, memcmp, etc).
+ */
+int PNGAPI
+png_sig_cmp(png_const_bytep sig, png_size_t start, png_size_t num_to_check)
+{
+ png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
+
+ if (num_to_check > 8)
+ num_to_check = 8;
+
+ else if (num_to_check < 1)
+ return (-1);
+
+ if (start > 7)
+ return (-1);
+
+ if (start + num_to_check > 8)
+ num_to_check = 8 - start;
+
+ return ((int)(memcmp(&sig[start], &png_signature[start], num_to_check)));
+}
+
+#endif /* READ */
+
+#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
+/* Function to allocate memory for zlib */
+PNG_FUNCTION(voidpf /* PRIVATE */,
+png_zalloc,(voidpf png_ptr, uInt items, uInt size),PNG_ALLOCATED)
+{
+ png_alloc_size_t num_bytes = size;
+
+ if (png_ptr == NULL)
+ return NULL;
+
+ if (items >= (~(png_alloc_size_t)0)/size)
+ {
+ png_warning (png_voidcast(png_structrp, png_ptr),
+ "Potential overflow in png_zalloc()");
+ return NULL;
+ }
+
+ num_bytes *= items;
+ return png_malloc_warn(png_voidcast(png_structrp, png_ptr), num_bytes);
+}
+
+/* Function to free memory for zlib */
+void /* PRIVATE */
+png_zfree(voidpf png_ptr, voidpf ptr)
+{
+ png_free(png_voidcast(png_const_structrp,png_ptr), ptr);
+}
+
+/* Reset the CRC variable to 32 bits of 1's. Care must be taken
+ * in case CRC is > 32 bits to leave the top bits 0.
+ */
+void /* PRIVATE */
+png_reset_crc(png_structrp png_ptr)
+{
+ /* The cast is safe because the crc is a 32-bit value. */
+ png_ptr->crc = (png_uint_32)crc32(0, Z_NULL, 0);
+}
+
+/* Calculate the CRC over a section of data. We can only pass as
+ * much data to this routine as the largest single buffer size. We
+ * also check that this data will actually be used before going to the
+ * trouble of calculating it.
+ */
+void /* PRIVATE */
+png_calculate_crc(png_structrp png_ptr, png_const_bytep ptr, png_size_t length)
+{
+ int need_crc = 1;
+
+ if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0)
+ {
+ if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
+ (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
+ need_crc = 0;
+ }
+
+ else /* critical */
+ {
+ if ((png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0)
+ need_crc = 0;
+ }
+
+ /* 'uLong' is defined in zlib.h as unsigned long; this means that on some
+ * systems it is a 64-bit value. crc32, however, returns 32 bits so the
+ * following cast is safe. 'uInt' may be no more than 16 bits, so it is
+ * necessary to perform a loop here.
+ */
+ if (need_crc != 0 && length > 0)
+ {
+ uLong crc = png_ptr->crc; /* Should never issue a warning */
+
+ do
+ {
+ uInt safe_length = (uInt)length;
+#ifndef __COVERITY__
+ if (safe_length == 0)
+ safe_length = (uInt)-1; /* evil, but safe */
+#endif
+
+ crc = crc32(crc, ptr, safe_length);
+
+ /* The following should never issue compiler warnings; if they do the
+ * target system has characteristics that will probably violate other
+ * assumptions within the libpng code.
+ */
+ ptr += safe_length;
+ length -= safe_length;
+ }
+ while (length > 0);
+
+ /* And the following is always safe because the crc is only 32 bits. */
+ png_ptr->crc = (png_uint_32)crc;
+ }
+}
+
+/* Check a user supplied version number, called from both read and write
+ * functions that create a png_struct.
+ */
+int
+png_user_version_check(png_structrp png_ptr, png_const_charp user_png_ver)
+{
+ /* Libpng versions 1.0.0 and later are binary compatible if the version
+ * string matches through the second '.'; we must recompile any
+ * applications that use any older library version.
+ */
+
+ if (user_png_ver != NULL)
+ {
+ int i = -1;
+ int found_dots = 0;
+
+ do
+ {
+ i++;
+ if (user_png_ver[i] != PNG_LIBPNG_VER_STRING[i])
+ png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
+ if (user_png_ver[i] == '.')
+ found_dots++;
+ } while (found_dots < 2 && user_png_ver[i] != 0 &&
+ PNG_LIBPNG_VER_STRING[i] != 0);
+ }
+
+ else
+ png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
+
+ if ((png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH) != 0)
+ {
+#ifdef PNG_WARNINGS_SUPPORTED
+ size_t pos = 0;
+ char m[128];
+
+ pos = png_safecat(m, (sizeof m), pos,
+ "Application built with libpng-");
+ pos = png_safecat(m, (sizeof m), pos, user_png_ver);
+ pos = png_safecat(m, (sizeof m), pos, " but running with ");
+ pos = png_safecat(m, (sizeof m), pos, PNG_LIBPNG_VER_STRING);
+ PNG_UNUSED(pos)
+
+ png_warning(png_ptr, m);
+#endif
+
+#ifdef PNG_ERROR_NUMBERS_SUPPORTED
+ png_ptr->flags = 0;
+#endif
+
+ return 0;
+ }
+
+ /* Success return. */
+ return 1;
+}
+
+/* Generic function to create a png_struct for either read or write - this
+ * contains the common initialization.
+ */
+PNG_FUNCTION(png_structp /* PRIVATE */,
+png_create_png_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
+ png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
+ png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
+{
+ png_struct create_struct;
+# ifdef PNG_SETJMP_SUPPORTED
+ jmp_buf create_jmp_buf;
+# endif
+
+ /* This temporary stack-allocated structure is used to provide a place to
+ * build enough context to allow the user provided memory allocator (if any)
+ * to be called.
+ */
+ memset(&create_struct, 0, (sizeof create_struct));
+
+ /* Added at libpng-1.2.6 */
+# ifdef PNG_USER_LIMITS_SUPPORTED
+ create_struct.user_width_max = PNG_USER_WIDTH_MAX;
+ create_struct.user_height_max = PNG_USER_HEIGHT_MAX;
+
+# ifdef PNG_USER_CHUNK_CACHE_MAX
+ /* Added at libpng-1.2.43 and 1.4.0 */
+ create_struct.user_chunk_cache_max = PNG_USER_CHUNK_CACHE_MAX;
+# endif
+
+# ifdef PNG_USER_CHUNK_MALLOC_MAX
+ /* Added at libpng-1.2.43 and 1.4.1, required only for read but exists
+ * in png_struct regardless.
+ */
+ create_struct.user_chunk_malloc_max = PNG_USER_CHUNK_MALLOC_MAX;
+# endif
+# endif
+
+ /* The following two API calls simply set fields in png_struct, so it is safe
+ * to do them now even though error handling is not yet set up.
+ */
+# ifdef PNG_USER_MEM_SUPPORTED
+ png_set_mem_fn(&create_struct, mem_ptr, malloc_fn, free_fn);
+# else
+ PNG_UNUSED(mem_ptr)
+ PNG_UNUSED(malloc_fn)
+ PNG_UNUSED(free_fn)
+# endif
+
+ /* (*error_fn) can return control to the caller after the error_ptr is set,
+ * this will result in a memory leak unless the error_fn does something
+ * extremely sophisticated. The design lacks merit but is implicit in the
+ * API.
+ */
+ png_set_error_fn(&create_struct, error_ptr, error_fn, warn_fn);
+
+# ifdef PNG_SETJMP_SUPPORTED
+ if (!setjmp(create_jmp_buf))
+# endif
+ {
+# ifdef PNG_SETJMP_SUPPORTED
+ /* Temporarily fake out the longjmp information until we have
+ * successfully completed this function. This only works if we have
+ * setjmp() support compiled in, but it is safe - this stuff should
+ * never happen.
+ */
+ create_struct.jmp_buf_ptr = &create_jmp_buf;
+ create_struct.jmp_buf_size = 0; /*stack allocation*/
+ create_struct.longjmp_fn = longjmp;
+# endif
+ /* Call the general version checker (shared with read and write code):
+ */
+ if (png_user_version_check(&create_struct, user_png_ver) != 0)
+ {
+ png_structrp png_ptr = png_voidcast(png_structrp,
+ png_malloc_warn(&create_struct, (sizeof *png_ptr)));
+
+ if (png_ptr != NULL)
+ {
+ /* png_ptr->zstream holds a back-pointer to the png_struct, so
+ * this can only be done now:
+ */
+ create_struct.zstream.zalloc = png_zalloc;
+ create_struct.zstream.zfree = png_zfree;
+ create_struct.zstream.opaque = png_ptr;
+
+# ifdef PNG_SETJMP_SUPPORTED
+ /* Eliminate the local error handling: */
+ create_struct.jmp_buf_ptr = NULL;
+ create_struct.jmp_buf_size = 0;
+ create_struct.longjmp_fn = 0;
+# endif
+
+ *png_ptr = create_struct;
+
+ /* This is the successful return point */
+ return png_ptr;
+ }
+ }
+ }
+
+ /* A longjmp because of a bug in the application storage allocator or a
+ * simple failure to allocate the png_struct.
+ */
+ return NULL;
+}
+
+/* Allocate the memory for an info_struct for the application. */
+PNG_FUNCTION(png_infop,PNGAPI
+png_create_info_struct,(png_const_structrp png_ptr),PNG_ALLOCATED)
+{
+ png_inforp info_ptr;
+
+ png_debug(1, "in png_create_info_struct");
+
+ if (png_ptr == NULL)
+ return NULL;
+
+ /* Use the internal API that does not (or at least should not) error out, so
+ * that this call always returns ok. The application typically sets up the
+ * error handling *after* creating the info_struct because this is the way it
+ * has always been done in 'example.c'.
+ */
+ info_ptr = png_voidcast(png_inforp, png_malloc_base(png_ptr,
+ (sizeof *info_ptr)));
+
+ if (info_ptr != NULL)
+ memset(info_ptr, 0, (sizeof *info_ptr));
+
+ return info_ptr;
+}
+
+/* This function frees the memory associated with a single info struct.
+ * Normally, one would use either png_destroy_read_struct() or
+ * png_destroy_write_struct() to free an info struct, but this may be
+ * useful for some applications. From libpng 1.6.0 this function is also used
+ * internally to implement the png_info release part of the 'struct' destroy
+ * APIs. This ensures that all possible approaches free the same data (all of
+ * it).
+ */
+void PNGAPI
+png_destroy_info_struct(png_const_structrp png_ptr, png_infopp info_ptr_ptr)
+{
+ png_inforp info_ptr = NULL;
+
+ png_debug(1, "in png_destroy_info_struct");
+
+ if (png_ptr == NULL)
+ return;
+
+ if (info_ptr_ptr != NULL)
+ info_ptr = *info_ptr_ptr;
+
+ if (info_ptr != NULL)
+ {
+ /* Do this first in case of an error below; if the app implements its own
+ * memory management this can lead to png_free calling png_error, which
+ * will abort this routine and return control to the app error handler.
+ * An infinite loop may result if it then tries to free the same info
+ * ptr.
+ */
+ *info_ptr_ptr = NULL;
+
+ png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
+ memset(info_ptr, 0, (sizeof *info_ptr));
+ png_free(png_ptr, info_ptr);
+ }
+}
+
+/* Initialize the info structure. This is now an internal function (0.89)
+ * and applications using it are urged to use png_create_info_struct()
+ * instead. Use deprecated in 1.6.0, internal use removed (used internally it
+ * is just a memset).
+ *
+ * NOTE: it is almost inconceivable that this API is used because it bypasses
+ * the user-memory mechanism and the user error handling/warning mechanisms in
+ * those cases where it does anything other than a memset.
+ */
+PNG_FUNCTION(void,PNGAPI
+png_info_init_3,(png_infopp ptr_ptr, png_size_t png_info_struct_size),
+ PNG_DEPRECATED)
+{
+ png_inforp info_ptr = *ptr_ptr;
+
+ png_debug(1, "in png_info_init_3");
+
+ if (info_ptr == NULL)
+ return;
+
+ if ((sizeof (png_info)) > png_info_struct_size)
+ {
+ *ptr_ptr = NULL;
+ /* The following line is why this API should not be used: */
+ free(info_ptr);
+ info_ptr = png_voidcast(png_inforp, png_malloc_base(NULL,
+ (sizeof *info_ptr)));
+ if (info_ptr == NULL)
+ return;
+ *ptr_ptr = info_ptr;
+ }
+
+ /* Set everything to 0 */
+ memset(info_ptr, 0, (sizeof *info_ptr));
+}
+
+/* The following API is not called internally */
+void PNGAPI
+png_data_freer(png_const_structrp png_ptr, png_inforp info_ptr,
+ int freer, png_uint_32 mask)
+{
+ png_debug(1, "in png_data_freer");
+
+ if (png_ptr == NULL || info_ptr == NULL)
+ return;
+
+ if (freer == PNG_DESTROY_WILL_FREE_DATA)
+ info_ptr->free_me |= mask;
+
+ else if (freer == PNG_USER_WILL_FREE_DATA)
+ info_ptr->free_me &= ~mask;
+
+ else
+ png_error(png_ptr, "Unknown freer parameter in png_data_freer");
+}
+
+void PNGAPI
+png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,
+ int num)
+{
+ png_debug(1, "in png_free_data");
+
+ if (png_ptr == NULL || info_ptr == NULL)
+ return;
+
+#ifdef PNG_TEXT_SUPPORTED
+ /* Free text item num or (if num == -1) all text items */
+ if (info_ptr->text != 0 &&
+ ((mask & PNG_FREE_TEXT) & info_ptr->free_me) != 0)
+ {
+ if (num != -1)
+ {
+ png_free(png_ptr, info_ptr->text[num].key);
+ info_ptr->text[num].key = NULL;
+ }
+
+ else
+ {
+ int i;
+
+ for (i = 0; i < info_ptr->num_text; i++)
+ png_free(png_ptr, info_ptr->text[i].key);
+
+ png_free(png_ptr, info_ptr->text);
+ info_ptr->text = NULL;
+ info_ptr->num_text = 0;
+ }
+ }
+#endif
+
+#ifdef PNG_tRNS_SUPPORTED
+ /* Free any tRNS entry */
+ if (((mask & PNG_FREE_TRNS) & info_ptr->free_me) != 0)
+ {
+ info_ptr->valid &= ~PNG_INFO_tRNS;
+ png_free(png_ptr, info_ptr->trans_alpha);
+ info_ptr->trans_alpha = NULL;
+ info_ptr->num_trans = 0;
+ }
+#endif
+
+#ifdef PNG_sCAL_SUPPORTED
+ /* Free any sCAL entry */
+ if (((mask & PNG_FREE_SCAL) & info_ptr->free_me) != 0)
+ {
+ png_free(png_ptr, info_ptr->scal_s_width);
+ png_free(png_ptr, info_ptr->scal_s_height);
+ info_ptr->scal_s_width = NULL;
+ info_ptr->scal_s_height = NULL;
+ info_ptr->valid &= ~PNG_INFO_sCAL;
+ }
+#endif
+
+#ifdef PNG_pCAL_SUPPORTED
+ /* Free any pCAL entry */
+ if (((mask & PNG_FREE_PCAL) & info_ptr->free_me) != 0)
+ {
+ png_free(png_ptr, info_ptr->pcal_purpose);
+ png_free(png_ptr, info_ptr->pcal_units);
+ info_ptr->pcal_purpose = NULL;
+ info_ptr->pcal_units = NULL;
+
+ if (info_ptr->pcal_params != NULL)
+ {
+ int i;
+
+ for (i = 0; i < info_ptr->pcal_nparams; i++)
+ png_free(png_ptr, info_ptr->pcal_params[i]);
+
+ png_free(png_ptr, info_ptr->pcal_params);
+ info_ptr->pcal_params = NULL;
+ }
+ info_ptr->valid &= ~PNG_INFO_pCAL;
+ }
+#endif
+
+#ifdef PNG_iCCP_SUPPORTED
+ /* Free any profile entry */
+ if (((mask & PNG_FREE_ICCP) & info_ptr->free_me) != 0)
+ {
+ png_free(png_ptr, info_ptr->iccp_name);
+ png_free(png_ptr, info_ptr->iccp_profile);
+ info_ptr->iccp_name = NULL;
+ info_ptr->iccp_profile = NULL;
+ info_ptr->valid &= ~PNG_INFO_iCCP;
+ }
+#endif
+
+#ifdef PNG_sPLT_SUPPORTED
+ /* Free a given sPLT entry, or (if num == -1) all sPLT entries */
+ if (info_ptr->splt_palettes != 0 &&
+ ((mask & PNG_FREE_SPLT) & info_ptr->free_me) != 0)
+ {
+ if (num != -1)
+ {
+ png_free(png_ptr, info_ptr->splt_palettes[num].name);
+ png_free(png_ptr, info_ptr->splt_palettes[num].entries);
+ info_ptr->splt_palettes[num].name = NULL;
+ info_ptr->splt_palettes[num].entries = NULL;
+ }
+
+ else
+ {
+ int i;
+
+ for (i = 0; i < info_ptr->splt_palettes_num; i++)
+ {
+ png_free(png_ptr, info_ptr->splt_palettes[i].name);
+ png_free(png_ptr, info_ptr->splt_palettes[i].entries);
+ }
+
+ png_free(png_ptr, info_ptr->splt_palettes);
+ info_ptr->splt_palettes = NULL;
+ info_ptr->splt_palettes_num = 0;
+ info_ptr->valid &= ~PNG_INFO_sPLT;
+ }
+ }
+#endif
+
+#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
+ if (info_ptr->unknown_chunks != 0 &&
+ ((mask & PNG_FREE_UNKN) & info_ptr->free_me) != 0)
+ {
+ if (num != -1)
+ {
+ png_free(png_ptr, info_ptr->unknown_chunks[num].data);
+ info_ptr->unknown_chunks[num].data = NULL;
+ }
+
+ else
+ {
+ int i;
+
+ for (i = 0; i < info_ptr->unknown_chunks_num; i++)
+ png_free(png_ptr, info_ptr->unknown_chunks[i].data);
+
+ png_free(png_ptr, info_ptr->unknown_chunks);
+ info_ptr->unknown_chunks = NULL;
+ info_ptr->unknown_chunks_num = 0;
+ }
+ }
+#endif
+
+#ifdef PNG_hIST_SUPPORTED
+ /* Free any hIST entry */
+ if (((mask & PNG_FREE_HIST) & info_ptr->free_me) != 0)
+ {
+ png_free(png_ptr, info_ptr->hist);
+ info_ptr->hist = NULL;
+ info_ptr->valid &= ~PNG_INFO_hIST;
+ }
+#endif
+
+ /* Free any PLTE entry that was internally allocated */
+ if (((mask & PNG_FREE_PLTE) & info_ptr->free_me) != 0)
+ {
+ png_free(png_ptr, info_ptr->palette);
+ info_ptr->palette = NULL;
+ info_ptr->valid &= ~PNG_INFO_PLTE;
+ info_ptr->num_palette = 0;
+ }
+
+#ifdef PNG_INFO_IMAGE_SUPPORTED
+ /* Free any image bits attached to the info structure */
+ if (((mask & PNG_FREE_ROWS) & info_ptr->free_me) != 0)
+ {
+ if (info_ptr->row_pointers != 0)
+ {
+ png_uint_32 row;
+ for (row = 0; row < info_ptr->height; row++)
+ png_free(png_ptr, info_ptr->row_pointers[row]);
+
+ png_free(png_ptr, info_ptr->row_pointers);
+ info_ptr->row_pointers = NULL;
+ }
+ info_ptr->valid &= ~PNG_INFO_IDAT;
+ }
+#endif
+
+ if (num != -1)
+ mask &= ~PNG_FREE_MUL;
+
+ info_ptr->free_me &= ~mask;
+}
+#endif /* READ || WRITE */
+
+/* This function returns a pointer to the io_ptr associated with the user
+ * functions. The application should free any memory associated with this
+ * pointer before png_write_destroy() or png_read_destroy() are called.
+ */
+png_voidp PNGAPI
+png_get_io_ptr(png_const_structrp png_ptr)
+{
+ if (png_ptr == NULL)
+ return (NULL);
+
+ return (png_ptr->io_ptr);
+}
+
+#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
+# ifdef PNG_STDIO_SUPPORTED
+/* Initialize the default input/output functions for the PNG file. If you
+ * use your own read or write routines, you can call either png_set_read_fn()
+ * or png_set_write_fn() instead of png_init_io(). If you have defined
+ * PNG_NO_STDIO or otherwise disabled PNG_STDIO_SUPPORTED, you must use a
+ * function of your own because "FILE *" isn't necessarily available.
+ */
+void PNGAPI
+png_init_io(png_structrp png_ptr, png_FILE_p fp)
+{
+ png_debug(1, "in png_init_io");
+
+ if (png_ptr == NULL)
+ return;
+
+ png_ptr->io_ptr = (png_voidp)fp;
+}
+# endif
+
+# ifdef PNG_SAVE_INT_32_SUPPORTED
+/* PNG signed integers are saved in 32-bit 2's complement format. ANSI C-90
+ * defines a cast of a signed integer to an unsigned integer either to preserve
+ * the value, if it is positive, or to calculate:
+ *
+ * (UNSIGNED_MAX+1) + integer
+ *
+ * Where UNSIGNED_MAX is the appropriate maximum unsigned value, so when the
+ * negative integral value is added the result will be an unsigned value
+ * correspnding to the 2's complement representation.
+ */
+void PNGAPI
+png_save_int_32(png_bytep buf, png_int_32 i)
+{
+ png_save_uint_32(buf, i);
+}
+# endif
+
+# ifdef PNG_TIME_RFC1123_SUPPORTED
+/* Convert the supplied time into an RFC 1123 string suitable for use in
+ * a "Creation Time" or other text-based time string.
+ */
+int PNGAPI
+png_convert_to_rfc1123_buffer(char out[29], png_const_timep ptime)
+{
+ static PNG_CONST char short_months[12][4] =
+ {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
+ "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
+
+ if (out == NULL)
+ return 0;
+
+ if (ptime->year > 9999 /* RFC1123 limitation */ ||
+ ptime->month == 0 || ptime->month > 12 ||
+ ptime->day == 0 || ptime->day > 31 ||
+ ptime->hour > 23 || ptime->minute > 59 ||
+ ptime->second > 60)
+ return 0;
+
+ {
+ size_t pos = 0;
+ char number_buf[5]; /* enough for a four-digit year */
+
+# define APPEND_STRING(string) pos = png_safecat(out, 29, pos, (string))
+# define APPEND_NUMBER(format, value)\
+ APPEND_STRING(PNG_FORMAT_NUMBER(number_buf, format, (value)))
+# define APPEND(ch) if (pos < 28) out[pos++] = (ch)
+
+ APPEND_NUMBER(PNG_NUMBER_FORMAT_u, (unsigned)ptime->day);
+ APPEND(' ');
+ APPEND_STRING(short_months[(ptime->month - 1)]);
+ APPEND(' ');
+ APPEND_NUMBER(PNG_NUMBER_FORMAT_u, ptime->year);
+ APPEND(' ');
+ APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->hour);
+ APPEND(':');
+ APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->minute);
+ APPEND(':');
+ APPEND_NUMBER(PNG_NUMBER_FORMAT_02u, (unsigned)ptime->second);
+ APPEND_STRING(" +0000"); /* This reliably terminates the buffer */
+ PNG_UNUSED (pos)
+
+# undef APPEND
+# undef APPEND_NUMBER
+# undef APPEND_STRING
+ }
+
+ return 1;
+}
+
+# if PNG_LIBPNG_VER < 10700
+/* To do: remove the following from libpng-1.7 */
+/* Original API that uses a private buffer in png_struct.
+ * Deprecated because it causes png_struct to carry a spurious temporary
+ * buffer (png_struct::time_buffer), better to have the caller pass this in.
+ */
+png_const_charp PNGAPI
+png_convert_to_rfc1123(png_structrp png_ptr, png_const_timep ptime)
+{
+ if (png_ptr != NULL)
+ {
+ /* The only failure above if png_ptr != NULL is from an invalid ptime */
+ if (png_convert_to_rfc1123_buffer(png_ptr->time_buffer, ptime) == 0)
+ png_warning(png_ptr, "Ignoring invalid time value");
+
+ else
+ return png_ptr->time_buffer;
+ }
+
+ return NULL;
+}
+# endif /* LIBPNG_VER < 10700 */
+# endif /* TIME_RFC1123 */
+
+#endif /* READ || WRITE */
+
+png_const_charp PNGAPI
+png_get_copyright(png_const_structrp png_ptr)
+{
+ PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
+#ifdef PNG_STRING_COPYRIGHT
+ return PNG_STRING_COPYRIGHT
+#else
+# ifdef __STDC__
+ return PNG_STRING_NEWLINE \
+ "libpng version 1.6.20 - December 3, 2015" PNG_STRING_NEWLINE \
+ "Copyright (c) 1998-2015 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
+ "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
+ "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
+ PNG_STRING_NEWLINE;
+# else
+ return "libpng version 1.6.20 - December 3, 2015\
+ Copyright (c) 1998-2015 Glenn Randers-Pehrson\
+ Copyright (c) 1996-1997 Andreas Dilger\
+ Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
+# endif
+#endif
+}
+
+/* The following return the library version as a short string in the
+ * format 1.0.0 through 99.99.99zz. To get the version of *.h files
+ * used with your application, print out PNG_LIBPNG_VER_STRING, which
+ * is defined in png.h.
+ * Note: now there is no difference between png_get_libpng_ver() and
+ * png_get_header_ver(). Due to the version_nn_nn_nn typedef guard,
+ * it is guaranteed that png.c uses the correct version of png.h.
+ */
+png_const_charp PNGAPI
+png_get_libpng_ver(png_const_structrp png_ptr)
+{
+ /* Version of *.c files used when building libpng */
+ return png_get_header_ver(png_ptr);
+}
+
+png_const_charp PNGAPI
+png_get_header_ver(png_const_structrp png_ptr)
+{
+ /* Version of *.h files used when building libpng */
+ PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
+ return PNG_LIBPNG_VER_STRING;
+}
+
+png_const_charp PNGAPI
+png_get_header_version(png_const_structrp png_ptr)
+{
+ /* Returns longer string containing both version and date */
+ PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
+#ifdef __STDC__
+ return PNG_HEADER_VERSION_STRING
+# ifndef PNG_READ_SUPPORTED
+ " (NO READ SUPPORT)"
+# endif
+ PNG_STRING_NEWLINE;
+#else
+ return PNG_HEADER_VERSION_STRING;
+#endif
+}
+
+#ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
+/* NOTE: this routine is not used internally! */
+/* Build a grayscale palette. Palette is assumed to be 1 << bit_depth
+ * large of png_color. This lets grayscale images be treated as
+ * paletted. Most useful for gamma correction and simplification
+ * of code. This API is not used internally.
+ */
+void PNGAPI
+png_build_grayscale_palette(int bit_depth, png_colorp palette)
+{
+ int num_palette;
+ int color_inc;
+ int i;
+ int v;
+
+ png_debug(1, "in png_do_build_grayscale_palette");
+
+ if (palette == NULL)
+ return;
+
+ switch (bit_depth)
+ {
+ case 1:
+ num_palette = 2;
+ color_inc = 0xff;
+ break;
+
+ case 2:
+ num_palette = 4;
+ color_inc = 0x55;
+ break;
+
+ case 4:
+ num_palette = 16;
+ color_inc = 0x11;
+ break;
+
+ case 8:
+ num_palette = 256;
+ color_inc = 1;
+ break;
+
+ default:
+ num_palette = 0;
+ color_inc = 0;
+ break;
+ }
+
+ for (i = 0, v = 0; i < num_palette; i++, v += color_inc)
+ {
+ palette[i].red = (png_byte)(v & 0xff);
+ palette[i].green = (png_byte)(v & 0xff);
+ palette[i].blue = (png_byte)(v & 0xff);
+ }
+}
+#endif
+
+#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
+int PNGAPI
+png_handle_as_unknown(png_const_structrp png_ptr, png_const_bytep chunk_name)
+{
+ /* Check chunk_name and return "keep" value if it's on the list, else 0 */
+ png_const_bytep p, p_end;
+
+ if (png_ptr == NULL || chunk_name == NULL || png_ptr->num_chunk_list == 0)
+ return PNG_HANDLE_CHUNK_AS_DEFAULT;
+
+ p_end = png_ptr->chunk_list;
+ p = p_end + png_ptr->num_chunk_list*5; /* beyond end */
+
+ /* The code is the fifth byte after each four byte string. Historically this
+ * code was always searched from the end of the list, this is no longer
+ * necessary because the 'set' routine handles duplicate entries correcty.
+ */
+ do /* num_chunk_list > 0, so at least one */
+ {
+ p -= 5;
+
+ if (memcmp(chunk_name, p, 4) == 0)
+ return p[4];
+ }
+ while (p > p_end);
+
+ /* This means that known chunks should be processed and unknown chunks should
+ * be handled according to the value of png_ptr->unknown_default; this can be
+ * confusing because, as a result, there are two levels of defaulting for
+ * unknown chunks.
+ */
+ return PNG_HANDLE_CHUNK_AS_DEFAULT;
+}
+
+#if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) ||\
+ defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
+int /* PRIVATE */
+png_chunk_unknown_handling(png_const_structrp png_ptr, png_uint_32 chunk_name)
+{
+ png_byte chunk_string[5];
+
+ PNG_CSTRING_FROM_CHUNK(chunk_string, chunk_name);
+ return png_handle_as_unknown(png_ptr, chunk_string);
+}
+#endif /* READ_UNKNOWN_CHUNKS || HANDLE_AS_UNKNOWN */
+#endif /* SET_UNKNOWN_CHUNKS */
+
+#ifdef PNG_READ_SUPPORTED
+/* This function, added to libpng-1.0.6g, is untested. */
+int PNGAPI
+png_reset_zstream(png_structrp png_ptr)
+{
+ if (png_ptr == NULL)
+ return Z_STREAM_ERROR;
+
+ /* WARNING: this resets the window bits to the maximum! */
+ return (inflateReset(&png_ptr->zstream));
+}
+#endif /* READ */
+
+/* This function was added to libpng-1.0.7 */
+png_uint_32 PNGAPI
+png_access_version_number(void)
+{
+ /* Version of *.c files used when building libpng */
+ return((png_uint_32)PNG_LIBPNG_VER);
+}
+
+#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
+/* Ensure that png_ptr->zstream.msg holds some appropriate error message string.
+ * If it doesn't 'ret' is used to set it to something appropriate, even in cases
+ * like Z_OK or Z_STREAM_END where the error code is apparently a success code.
+ */
+void /* PRIVATE */
+png_zstream_error(png_structrp png_ptr, int ret)
+{
+ /* Translate 'ret' into an appropriate error string, priority is given to the
+ * one in zstream if set. This always returns a string, even in cases like
+ * Z_OK or Z_STREAM_END where the error code is a success code.
+ */
+ if (png_ptr->zstream.msg == NULL) switch (ret)
+ {
+ default:
+ case Z_OK:
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return code");
+ break;
+
+ case Z_STREAM_END:
+ /* Normal exit */
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected end of LZ stream");
+ break;
+
+ case Z_NEED_DICT:
+ /* This means the deflate stream did not have a dictionary; this
+ * indicates a bogus PNG.
+ */
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("missing LZ dictionary");
+ break;
+
+ case Z_ERRNO:
+ /* gz APIs only: should not happen */
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("zlib IO error");
+ break;
+
+ case Z_STREAM_ERROR:
+ /* internal libpng error */
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("bad parameters to zlib");
+ break;
+
+ case Z_DATA_ERROR:
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("damaged LZ stream");
+ break;
+
+ case Z_MEM_ERROR:
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("insufficient memory");
+ break;
+
+ case Z_BUF_ERROR:
+ /* End of input or output; not a problem if the caller is doing
+ * incremental read or write.
+ */
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("truncated");
+ break;
+
+ case Z_VERSION_ERROR:
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("unsupported zlib version");
+ break;
+
+ case PNG_UNEXPECTED_ZLIB_RETURN:
+ /* Compile errors here mean that zlib now uses the value co-opted in
+ * pngpriv.h for PNG_UNEXPECTED_ZLIB_RETURN; update the switch above
+ * and change pngpriv.h. Note that this message is "... return",
+ * whereas the default/Z_OK one is "... return code".
+ */
+ png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return");
+ break;
+ }
+}
+
+/* png_convert_size: a PNGAPI but no longer in png.h, so deleted
+ * at libpng 1.5.5!
+ */
+
+/* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */
+#ifdef PNG_GAMMA_SUPPORTED /* always set if COLORSPACE */
+static int
+png_colorspace_check_gamma(png_const_structrp png_ptr,
+ png_colorspacerp colorspace, png_fixed_point gAMA, int from)
+ /* This is called to check a new gamma value against an existing one. The
+ * routine returns false if the new gamma value should not be written.
+ *
+ * 'from' says where the new gamma value comes from:
+ *
+ * 0: the new gamma value is the libpng estimate for an ICC profile
+ * 1: the new gamma value comes from a gAMA chunk
+ * 2: the new gamma value comes from an sRGB chunk
+ */
+{
+ png_fixed_point gtest;
+
+ if ((colorspace->flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 &&
+ (png_muldiv(>est, colorspace->gamma, PNG_FP_1, gAMA) == 0 ||
+ png_gamma_significant(gtest) != 0))
+ {
+ /* Either this is an sRGB image, in which case the calculated gamma
+ * approximation should match, or this is an image with a profile and the
+ * value libpng calculates for the gamma of the profile does not match the
+ * value recorded in the file. The former, sRGB, case is an error, the
+ * latter is just a warning.
+ */
+ if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0 || from == 2)
+ {
+ png_chunk_report(png_ptr, "gamma value does not match sRGB",
+ PNG_CHUNK_ERROR);
+ /* Do not overwrite an sRGB value */
+ return from == 2;
+ }
+
+ else /* sRGB tag not involved */
+ {
+ png_chunk_report(png_ptr, "gamma value does not match libpng estimate",
+ PNG_CHUNK_WARNING);
+ return from == 1;
+ }
+ }
+
+ return 1;
+}
+
+void /* PRIVATE */
+png_colorspace_set_gamma(png_const_structrp png_ptr,
+ png_colorspacerp colorspace, png_fixed_point gAMA)
+{
+ /* Changed in libpng-1.5.4 to limit the values to ensure overflow can't
+ * occur. Since the fixed point representation is asymetrical it is
+ * possible for 1/gamma to overflow the limit of 21474 and this means the
+ * gamma value must be at least 5/100000 and hence at most 20000.0. For
+ * safety the limits here are a little narrower. The values are 0.00016 to
+ * 6250.0, which are truly ridiculous gamma values (and will produce
+ * displays that are all black or all white.)
+ *
+ * In 1.6.0 this test replaces the ones in pngrutil.c, in the gAMA chunk
+ * handling code, which only required the value to be >0.
+ */
+ png_const_charp errmsg;
+
+ if (gAMA < 16 || gAMA > 625000000)
+ errmsg = "gamma value out of range";
+
+# ifdef PNG_READ_gAMA_SUPPORTED
+ /* Allow the application to set the gamma value more than once */
+ else if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
+ (colorspace->flags & PNG_COLORSPACE_FROM_gAMA) != 0)
+ errmsg = "duplicate";
+# endif
+
+ /* Do nothing if the colorspace is already invalid */
+ else if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
+ return;
+
+ else
+ {
+ if (png_colorspace_check_gamma(png_ptr, colorspace, gAMA,
+ 1/*from gAMA*/) != 0)
+ {
+ /* Store this gamma value. */
+ colorspace->gamma = gAMA;
+ colorspace->flags |=
+ (PNG_COLORSPACE_HAVE_GAMMA | PNG_COLORSPACE_FROM_gAMA);
+ }
+
+ /* At present if the check_gamma test fails the gamma of the colorspace is
+ * not updated however the colorspace is not invalidated. This
+ * corresponds to the case where the existing gamma comes from an sRGB
+ * chunk or profile. An error message has already been output.
+ */
+ return;
+ }
+
+ /* Error exit - errmsg has been set. */
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+ png_chunk_report(png_ptr, errmsg, PNG_CHUNK_WRITE_ERROR);
+}
+
+void /* PRIVATE */
+png_colorspace_sync_info(png_const_structrp png_ptr, png_inforp info_ptr)
+{
+ if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
+ {
+ /* Everything is invalid */
+ info_ptr->valid &= ~(PNG_INFO_gAMA|PNG_INFO_cHRM|PNG_INFO_sRGB|
+ PNG_INFO_iCCP);
+
+# ifdef PNG_COLORSPACE_SUPPORTED
+ /* Clean up the iCCP profile now if it won't be used. */
+ png_free_data(png_ptr, info_ptr, PNG_FREE_ICCP, -1/*not used*/);
+# else
+ PNG_UNUSED(png_ptr)
+# endif
+ }
+
+ else
+ {
+# ifdef PNG_COLORSPACE_SUPPORTED
+ /* Leave the INFO_iCCP flag set if the pngset.c code has already set
+ * it; this allows a PNG to contain a profile which matches sRGB and
+ * yet still have that profile retrievable by the application.
+ */
+ if ((info_ptr->colorspace.flags & PNG_COLORSPACE_MATCHES_sRGB) != 0)
+ info_ptr->valid |= PNG_INFO_sRGB;
+
+ else
+ info_ptr->valid &= ~PNG_INFO_sRGB;
+
+ if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
+ info_ptr->valid |= PNG_INFO_cHRM;
+
+ else
+ info_ptr->valid &= ~PNG_INFO_cHRM;
+# endif
+
+ if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) != 0)
+ info_ptr->valid |= PNG_INFO_gAMA;
+
+ else
+ info_ptr->valid &= ~PNG_INFO_gAMA;
+ }
+}
+
+#ifdef PNG_READ_SUPPORTED
+void /* PRIVATE */
+png_colorspace_sync(png_const_structrp png_ptr, png_inforp info_ptr)
+{
+ if (info_ptr == NULL) /* reduce code size; check here not in the caller */
+ return;
+
+ info_ptr->colorspace = png_ptr->colorspace;
+ png_colorspace_sync_info(png_ptr, info_ptr);
+}
+#endif
+#endif /* GAMMA */
+
+#ifdef PNG_COLORSPACE_SUPPORTED
+/* Added at libpng-1.5.5 to support read and write of true CIEXYZ values for
+ * cHRM, as opposed to using chromaticities. These internal APIs return
+ * non-zero on a parameter error. The X, Y and Z values are required to be
+ * positive and less than 1.0.
+ */
+static int
+png_xy_from_XYZ(png_xy *xy, const png_XYZ *XYZ)
+{
+ png_int_32 d, dwhite, whiteX, whiteY;
+
+ d = XYZ->red_X + XYZ->red_Y + XYZ->red_Z;
+ if (png_muldiv(&xy->redx, XYZ->red_X, PNG_FP_1, d) == 0)
+ return 1;
+ if (png_muldiv(&xy->redy, XYZ->red_Y, PNG_FP_1, d) == 0)
+ return 1;
+ dwhite = d;
+ whiteX = XYZ->red_X;
+ whiteY = XYZ->red_Y;
+
+ d = XYZ->green_X + XYZ->green_Y + XYZ->green_Z;
+ if (png_muldiv(&xy->greenx, XYZ->green_X, PNG_FP_1, d) == 0)
+ return 1;
+ if (png_muldiv(&xy->greeny, XYZ->green_Y, PNG_FP_1, d) == 0)
+ return 1;
+ dwhite += d;
+ whiteX += XYZ->green_X;
+ whiteY += XYZ->green_Y;
+
+ d = XYZ->blue_X + XYZ->blue_Y + XYZ->blue_Z;
+ if (png_muldiv(&xy->bluex, XYZ->blue_X, PNG_FP_1, d) == 0)
+ return 1;
+ if (png_muldiv(&xy->bluey, XYZ->blue_Y, PNG_FP_1, d) == 0)
+ return 1;
+ dwhite += d;
+ whiteX += XYZ->blue_X;
+ whiteY += XYZ->blue_Y;
+
+ /* The reference white is simply the sum of the end-point (X,Y,Z) vectors,
+ * thus:
+ */
+ if (png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite) == 0)
+ return 1;
+ if (png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite) == 0)
+ return 1;
+
+ return 0;
+}
+
+static int
+png_XYZ_from_xy(png_XYZ *XYZ, const png_xy *xy)
+{
+ png_fixed_point red_inverse, green_inverse, blue_scale;
+ png_fixed_point left, right, denominator;
+
+ /* Check xy and, implicitly, z. Note that wide gamut color spaces typically
+ * have end points with 0 tristimulus values (these are impossible end
+ * points, but they are used to cover the possible colors). We check
+ * xy->whitey against 5, not 0, to avoid a possible integer overflow.
+ */
+ if (xy->redx < 0 || xy->redx > PNG_FP_1) return 1;
+ if (xy->redy < 0 || xy->redy > PNG_FP_1-xy->redx) return 1;
+ if (xy->greenx < 0 || xy->greenx > PNG_FP_1) return 1;
+ if (xy->greeny < 0 || xy->greeny > PNG_FP_1-xy->greenx) return 1;
+ if (xy->bluex < 0 || xy->bluex > PNG_FP_1) return 1;
+ if (xy->bluey < 0 || xy->bluey > PNG_FP_1-xy->bluex) return 1;
+ if (xy->whitex < 0 || xy->whitex > PNG_FP_1) return 1;
+ if (xy->whitey < 5 || xy->whitey > PNG_FP_1-xy->whitex) return 1;
+
+ /* The reverse calculation is more difficult because the original tristimulus
+ * value had 9 independent values (red,green,blue)x(X,Y,Z) however only 8
+ * derived values were recorded in the cHRM chunk;
+ * (red,green,blue,white)x(x,y). This loses one degree of freedom and
+ * therefore an arbitrary ninth value has to be introduced to undo the
+ * original transformations.
+ *
+ * Think of the original end-points as points in (X,Y,Z) space. The
+ * chromaticity values (c) have the property:
+ *
+ * C
+ * c = ---------
+ * X + Y + Z
+ *
+ * For each c (x,y,z) from the corresponding original C (X,Y,Z). Thus the
+ * three chromaticity values (x,y,z) for each end-point obey the
+ * relationship:
+ *
+ * x + y + z = 1
+ *
+ * This describes the plane in (X,Y,Z) space that intersects each axis at the
+ * value 1.0; call this the chromaticity plane. Thus the chromaticity
+ * calculation has scaled each end-point so that it is on the x+y+z=1 plane
+ * and chromaticity is the intersection of the vector from the origin to the
+ * (X,Y,Z) value with the chromaticity plane.
+ *
+ * To fully invert the chromaticity calculation we would need the three
+ * end-point scale factors, (red-scale, green-scale, blue-scale), but these
+ * were not recorded. Instead we calculated the reference white (X,Y,Z) and
+ * recorded the chromaticity of this. The reference white (X,Y,Z) would have
+ * given all three of the scale factors since:
+ *
+ * color-C = color-c * color-scale
+ * white-C = red-C + green-C + blue-C
+ * = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
+ *
+ * But cHRM records only white-x and white-y, so we have lost the white scale
+ * factor:
+ *
+ * white-C = white-c*white-scale
+ *
+ * To handle this the inverse transformation makes an arbitrary assumption
+ * about white-scale:
+ *
+ * Assume: white-Y = 1.0
+ * Hence: white-scale = 1/white-y
+ * Or: red-Y + green-Y + blue-Y = 1.0
+ *
+ * Notice the last statement of the assumption gives an equation in three of
+ * the nine values we want to calculate. 8 more equations come from the
+ * above routine as summarised at the top above (the chromaticity
+ * calculation):
+ *
+ * Given: color-x = color-X / (color-X + color-Y + color-Z)
+ * Hence: (color-x - 1)*color-X + color.x*color-Y + color.x*color-Z = 0
+ *
+ * This is 9 simultaneous equations in the 9 variables "color-C" and can be
+ * solved by Cramer's rule. Cramer's rule requires calculating 10 9x9 matrix
+ * determinants, however this is not as bad as it seems because only 28 of
+ * the total of 90 terms in the various matrices are non-zero. Nevertheless
+ * Cramer's rule is notoriously numerically unstable because the determinant
+ * calculation involves the difference of large, but similar, numbers. It is
+ * difficult to be sure that the calculation is stable for real world values
+ * and it is certain that it becomes unstable where the end points are close
+ * together.
+ *
+ * So this code uses the perhaps slightly less optimal but more
+ * understandable and totally obvious approach of calculating color-scale.
+ *
+ * This algorithm depends on the precision in white-scale and that is
+ * (1/white-y), so we can immediately see that as white-y approaches 0 the
+ * accuracy inherent in the cHRM chunk drops off substantially.
+ *
+ * libpng arithmetic: a simple inversion of the above equations
+ * ------------------------------------------------------------
+ *
+ * white_scale = 1/white-y
+ * white-X = white-x * white-scale
+ * white-Y = 1.0
+ * white-Z = (1 - white-x - white-y) * white_scale
+ *
+ * white-C = red-C + green-C + blue-C
+ * = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
+ *
+ * This gives us three equations in (red-scale,green-scale,blue-scale) where
+ * all the coefficients are now known:
+ *
+ * red-x*red-scale + green-x*green-scale + blue-x*blue-scale
+ * = white-x/white-y
+ * red-y*red-scale + green-y*green-scale + blue-y*blue-scale = 1
+ * red-z*red-scale + green-z*green-scale + blue-z*blue-scale
+ * = (1 - white-x - white-y)/white-y
+ *
+ * In the last equation color-z is (1 - color-x - color-y) so we can add all
+ * three equations together to get an alternative third:
+ *
+ * red-scale + green-scale + blue-scale = 1/white-y = white-scale
+ *
+ * So now we have a Cramer's rule solution where the determinants are just
+ * 3x3 - far more tractible. Unfortunately 3x3 determinants still involve
+ * multiplication of three coefficients so we can't guarantee to avoid
+ * overflow in the libpng fixed point representation. Using Cramer's rule in
+ * floating point is probably a good choice here, but it's not an option for
+ * fixed point. Instead proceed to simplify the first two equations by
+ * eliminating what is likely to be the largest value, blue-scale:
+ *
+ * blue-scale = white-scale - red-scale - green-scale
+ *
+ * Hence:
+ *
+ * (red-x - blue-x)*red-scale + (green-x - blue-x)*green-scale =
+ * (white-x - blue-x)*white-scale
+ *
+ * (red-y - blue-y)*red-scale + (green-y - blue-y)*green-scale =
+ * 1 - blue-y*white-scale
+ *
+ * And now we can trivially solve for (red-scale,green-scale):
+ *
+ * green-scale =
+ * (white-x - blue-x)*white-scale - (red-x - blue-x)*red-scale
+ * -----------------------------------------------------------
+ * green-x - blue-x
+ *
+ * red-scale =
+ * 1 - blue-y*white-scale - (green-y - blue-y) * green-scale
+ * ---------------------------------------------------------
+ * red-y - blue-y
+ *
+ * Hence:
+ *
+ * red-scale =
+ * ( (green-x - blue-x) * (white-y - blue-y) -
+ * (green-y - blue-y) * (white-x - blue-x) ) / white-y
+ * -------------------------------------------------------------------------
+ * (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
+ *
+ * green-scale =
+ * ( (red-y - blue-y) * (white-x - blue-x) -
+ * (red-x - blue-x) * (white-y - blue-y) ) / white-y
+ * -------------------------------------------------------------------------
+ * (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
+ *
+ * Accuracy:
+ * The input values have 5 decimal digits of accuracy. The values are all in
+ * the range 0 < value < 1, so simple products are in the same range but may
+ * need up to 10 decimal digits to preserve the original precision and avoid
+ * underflow. Because we are using a 32-bit signed representation we cannot
+ * match this; the best is a little over 9 decimal digits, less than 10.
+ *
+ * The approach used here is to preserve the maximum precision within the
+ * signed representation. Because the red-scale calculation above uses the
+ * difference between two products of values that must be in the range -1..+1
+ * it is sufficient to divide the product by 7; ceil(100,000/32767*2). The
+ * factor is irrelevant in the calculation because it is applied to both
+ * numerator and denominator.
+ *
+ * Note that the values of the differences of the products of the
+ * chromaticities in the above equations tend to be small, for example for
+ * the sRGB chromaticities they are:
+ *
+ * red numerator: -0.04751
+ * green numerator: -0.08788
+ * denominator: -0.2241 (without white-y multiplication)
+ *
+ * The resultant Y coefficients from the chromaticities of some widely used
+ * color space definitions are (to 15 decimal places):
+ *
+ * sRGB
+ * 0.212639005871510 0.715168678767756 0.072192315360734
+ * Kodak ProPhoto
+ * 0.288071128229293 0.711843217810102 0.000085653960605
+ * Adobe RGB
+ * 0.297344975250536 0.627363566255466 0.075291458493998
+ * Adobe Wide Gamut RGB
+ * 0.258728243040113 0.724682314948566 0.016589442011321
+ */
+ /* By the argument, above overflow should be impossible here. The return
+ * value of 2 indicates an internal error to the caller.
+ */
+ if (png_muldiv(&left, xy->greenx-xy->bluex, xy->redy - xy->bluey, 7) == 0)
+ return 2;
+ if (png_muldiv(&right, xy->greeny-xy->bluey, xy->redx - xy->bluex, 7) == 0)
+ return 2;
+ denominator = left - right;
+
+ /* Now find the red numerator. */
+ if (png_muldiv(&left, xy->greenx-xy->bluex, xy->whitey-xy->bluey, 7) == 0)
+ return 2;
+ if (png_muldiv(&right, xy->greeny-xy->bluey, xy->whitex-xy->bluex, 7) == 0)
+ return 2;
+
+ /* Overflow is possible here and it indicates an extreme set of PNG cHRM
+ * chunk values. This calculation actually returns the reciprocal of the
+ * scale value because this allows us to delay the multiplication of white-y
+ * into the denominator, which tends to produce a small number.
+ */
+ if (png_muldiv(&red_inverse, xy->whitey, denominator, left-right) == 0 ||
+ red_inverse <= xy->whitey /* r+g+b scales = white scale */)
+ return 1;
+
+ /* Similarly for green_inverse: */
+ if (png_muldiv(&left, xy->redy-xy->bluey, xy->whitex-xy->bluex, 7) == 0)
+ return 2;
+ if (png_muldiv(&right, xy->redx-xy->bluex, xy->whitey-xy->bluey, 7) == 0)
+ return 2;
+ if (png_muldiv(&green_inverse, xy->whitey, denominator, left-right) == 0 ||
+ green_inverse <= xy->whitey)
+ return 1;
+
+ /* And the blue scale, the checks above guarantee this can't overflow but it
+ * can still produce 0 for extreme cHRM values.
+ */
+ blue_scale = png_reciprocal(xy->whitey) - png_reciprocal(red_inverse) -
+ png_reciprocal(green_inverse);
+ if (blue_scale <= 0)
+ return 1;
+
+
+ /* And fill in the png_XYZ: */
+ if (png_muldiv(&XYZ->red_X, xy->redx, PNG_FP_1, red_inverse) == 0)
+ return 1;
+ if (png_muldiv(&XYZ->red_Y, xy->redy, PNG_FP_1, red_inverse) == 0)
+ return 1;
+ if (png_muldiv(&XYZ->red_Z, PNG_FP_1 - xy->redx - xy->redy, PNG_FP_1,
+ red_inverse) == 0)
+ return 1;
+
+ if (png_muldiv(&XYZ->green_X, xy->greenx, PNG_FP_1, green_inverse) == 0)
+ return 1;
+ if (png_muldiv(&XYZ->green_Y, xy->greeny, PNG_FP_1, green_inverse) == 0)
+ return 1;
+ if (png_muldiv(&XYZ->green_Z, PNG_FP_1 - xy->greenx - xy->greeny, PNG_FP_1,
+ green_inverse) == 0)
+ return 1;
+
+ if (png_muldiv(&XYZ->blue_X, xy->bluex, blue_scale, PNG_FP_1) == 0)
+ return 1;
+ if (png_muldiv(&XYZ->blue_Y, xy->bluey, blue_scale, PNG_FP_1) == 0)
+ return 1;
+ if (png_muldiv(&XYZ->blue_Z, PNG_FP_1 - xy->bluex - xy->bluey, blue_scale,
+ PNG_FP_1) == 0)
+ return 1;
+
+ return 0; /*success*/
+}
+
+static int
+png_XYZ_normalize(png_XYZ *XYZ)
+{
+ png_int_32 Y;
+
+ if (XYZ->red_Y < 0 || XYZ->green_Y < 0 || XYZ->blue_Y < 0 ||
+ XYZ->red_X < 0 || XYZ->green_X < 0 || XYZ->blue_X < 0 ||
+ XYZ->red_Z < 0 || XYZ->green_Z < 0 || XYZ->blue_Z < 0)
+ return 1;
+
+ /* Normalize by scaling so the sum of the end-point Y values is PNG_FP_1.
+ * IMPLEMENTATION NOTE: ANSI requires signed overflow not to occur, therefore
+ * relying on addition of two positive values producing a negative one is not
+ * safe.
+ */
+ Y = XYZ->red_Y;
+ if (0x7fffffff - Y < XYZ->green_X)
+ return 1;
+ Y += XYZ->green_Y;
+ if (0x7fffffff - Y < XYZ->blue_X)
+ return 1;
+ Y += XYZ->blue_Y;
+
+ if (Y != PNG_FP_1)
+ {
+ if (png_muldiv(&XYZ->red_X, XYZ->red_X, PNG_FP_1, Y) == 0)
+ return 1;
+ if (png_muldiv(&XYZ->red_Y, XYZ->red_Y, PNG_FP_1, Y) == 0)
+ return 1;
+ if (png_muldiv(&XYZ->red_Z, XYZ->red_Z, PNG_FP_1, Y) == 0)
+ return 1;
+
+ if (png_muldiv(&XYZ->green_X, XYZ->green_X, PNG_FP_1, Y) == 0)
+ return 1;
+ if (png_muldiv(&XYZ->green_Y, XYZ->green_Y, PNG_FP_1, Y) == 0)
+ return 1;
+ if (png_muldiv(&XYZ->green_Z, XYZ->green_Z, PNG_FP_1, Y) == 0)
+ return 1;
+
+ if (png_muldiv(&XYZ->blue_X, XYZ->blue_X, PNG_FP_1, Y) == 0)
+ return 1;
+ if (png_muldiv(&XYZ->blue_Y, XYZ->blue_Y, PNG_FP_1, Y) == 0)
+ return 1;
+ if (png_muldiv(&XYZ->blue_Z, XYZ->blue_Z, PNG_FP_1, Y) == 0)
+ return 1;
+ }
+
+ return 0;
+}
+
+static int
+png_colorspace_endpoints_match(const png_xy *xy1, const png_xy *xy2, int delta)
+{
+ /* Allow an error of +/-0.01 (absolute value) on each chromaticity */
+ if (PNG_OUT_OF_RANGE(xy1->whitex, xy2->whitex,delta) ||
+ PNG_OUT_OF_RANGE(xy1->whitey, xy2->whitey,delta) ||
+ PNG_OUT_OF_RANGE(xy1->redx, xy2->redx, delta) ||
+ PNG_OUT_OF_RANGE(xy1->redy, xy2->redy, delta) ||
+ PNG_OUT_OF_RANGE(xy1->greenx, xy2->greenx,delta) ||
+ PNG_OUT_OF_RANGE(xy1->greeny, xy2->greeny,delta) ||
+ PNG_OUT_OF_RANGE(xy1->bluex, xy2->bluex, delta) ||
+ PNG_OUT_OF_RANGE(xy1->bluey, xy2->bluey, delta))
+ return 0;
+ return 1;
+}
+
+/* Added in libpng-1.6.0, a different check for the validity of a set of cHRM
+ * chunk chromaticities. Earlier checks used to simply look for the overflow
+ * condition (where the determinant of the matrix to solve for XYZ ends up zero
+ * because the chromaticity values are not all distinct.) Despite this it is
+ * theoretically possible to produce chromaticities that are apparently valid
+ * but that rapidly degrade to invalid, potentially crashing, sets because of
+ * arithmetic inaccuracies when calculations are performed on them. The new
+ * check is to round-trip xy -> XYZ -> xy and then check that the result is
+ * within a small percentage of the original.
+ */
+static int
+png_colorspace_check_xy(png_XYZ *XYZ, const png_xy *xy)
+{
+ int result;
+ png_xy xy_test;
+
+ /* As a side-effect this routine also returns the XYZ endpoints. */
+ result = png_XYZ_from_xy(XYZ, xy);
+ if (result != 0)
+ return result;
+
+ result = png_xy_from_XYZ(&xy_test, XYZ);
+ if (result != 0)
+ return result;
+
+ if (png_colorspace_endpoints_match(xy, &xy_test,
+ 5/*actually, the math is pretty accurate*/) != 0)
+ return 0;
+
+ /* Too much slip */
+ return 1;
+}
+
+/* This is the check going the other way. The XYZ is modified to normalize it
+ * (another side-effect) and the xy chromaticities are returned.
+ */
+static int
+png_colorspace_check_XYZ(png_xy *xy, png_XYZ *XYZ)
+{
+ int result;
+ png_XYZ XYZtemp;
+
+ result = png_XYZ_normalize(XYZ);
+ if (result != 0)
+ return result;
+
+ result = png_xy_from_XYZ(xy, XYZ);
+ if (result != 0)
+ return result;
+
+ XYZtemp = *XYZ;
+ return png_colorspace_check_xy(&XYZtemp, xy);
+}
+
+/* Used to check for an endpoint match against sRGB */
+static const png_xy sRGB_xy = /* From ITU-R BT.709-3 */
+{
+ /* color x y */
+ /* red */ 64000, 33000,
+ /* green */ 30000, 60000,
+ /* blue */ 15000, 6000,
+ /* white */ 31270, 32900
+};
+
+static int
+png_colorspace_set_xy_and_XYZ(png_const_structrp png_ptr,
+ png_colorspacerp colorspace, const png_xy *xy, const png_XYZ *XYZ,
+ int preferred)
+{
+ if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
+ return 0;
+
+ /* The consistency check is performed on the chromaticities; this factors out
+ * variations because of the normalization (or not) of the end point Y
+ * values.
+ */
+ if (preferred < 2 &&
+ (colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
+ {
+ /* The end points must be reasonably close to any we already have. The
+ * following allows an error of up to +/-.001
+ */
+ if (png_colorspace_endpoints_match(xy, &colorspace->end_points_xy,
+ 100) == 0)
+ {
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+ png_benign_error(png_ptr, "inconsistent chromaticities");
+ return 0; /* failed */
+ }
+
+ /* Only overwrite with preferred values */
+ if (preferred == 0)
+ return 1; /* ok, but no change */
+ }
+
+ colorspace->end_points_xy = *xy;
+ colorspace->end_points_XYZ = *XYZ;
+ colorspace->flags |= PNG_COLORSPACE_HAVE_ENDPOINTS;
+
+ /* The end points are normally quoted to two decimal digits, so allow +/-0.01
+ * on this test.
+ */
+ if (png_colorspace_endpoints_match(xy, &sRGB_xy, 1000) != 0)
+ colorspace->flags |= PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB;
+
+ else
+ colorspace->flags &= PNG_COLORSPACE_CANCEL(
+ PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
+
+ return 2; /* ok and changed */
+}
+
+int /* PRIVATE */
+png_colorspace_set_chromaticities(png_const_structrp png_ptr,
+ png_colorspacerp colorspace, const png_xy *xy, int preferred)
+{
+ /* We must check the end points to ensure they are reasonable - in the past
+ * color management systems have crashed as a result of getting bogus
+ * colorant values, while this isn't the fault of libpng it is the
+ * responsibility of libpng because PNG carries the bomb and libpng is in a
+ * position to protect against it.
+ */
+ png_XYZ XYZ;
+
+ switch (png_colorspace_check_xy(&XYZ, xy))
+ {
+ case 0: /* success */
+ return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, xy, &XYZ,
+ preferred);
+
+ case 1:
+ /* We can't invert the chromaticities so we can't produce value XYZ
+ * values. Likely as not a color management system will fail too.
+ */
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+ png_benign_error(png_ptr, "invalid chromaticities");
+ break;
+
+ default:
+ /* libpng is broken; this should be a warning but if it happens we
+ * want error reports so for the moment it is an error.
+ */
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+ png_error(png_ptr, "internal error checking chromaticities");
+ }
+
+ return 0; /* failed */
+}
+
+int /* PRIVATE */
+png_colorspace_set_endpoints(png_const_structrp png_ptr,
+ png_colorspacerp colorspace, const png_XYZ *XYZ_in, int preferred)
+{
+ png_XYZ XYZ = *XYZ_in;
+ png_xy xy;
+
+ switch (png_colorspace_check_XYZ(&xy, &XYZ))
+ {
+ case 0:
+ return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, &xy, &XYZ,
+ preferred);
+
+ case 1:
+ /* End points are invalid. */
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+ png_benign_error(png_ptr, "invalid end points");
+ break;
+
+ default:
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+ png_error(png_ptr, "internal error checking chromaticities");
+ }
+
+ return 0; /* failed */
+}
+
+#if defined(PNG_sRGB_SUPPORTED) || defined(PNG_iCCP_SUPPORTED)
+/* Error message generation */
+static char
+png_icc_tag_char(png_uint_32 byte)
+{
+ byte &= 0xff;
+ if (byte >= 32 && byte <= 126)
+ return (char)byte;
+ else
+ return '?';
+}
+
+static void
+png_icc_tag_name(char *name, png_uint_32 tag)
+{
+ name[0] = '\'';
+ name[1] = png_icc_tag_char(tag >> 24);
+ name[2] = png_icc_tag_char(tag >> 16);
+ name[3] = png_icc_tag_char(tag >> 8);
+ name[4] = png_icc_tag_char(tag );
+ name[5] = '\'';
+}
+
+static int
+is_ICC_signature_char(png_alloc_size_t it)
+{
+ return it == 32 || (it >= 48 && it <= 57) || (it >= 65 && it <= 90) ||
+ (it >= 97 && it <= 122);
+}
+
+static int
+is_ICC_signature(png_alloc_size_t it)
+{
+ return is_ICC_signature_char(it >> 24) /* checks all the top bits */ &&
+ is_ICC_signature_char((it >> 16) & 0xff) &&
+ is_ICC_signature_char((it >> 8) & 0xff) &&
+ is_ICC_signature_char(it & 0xff);
+}
+
+static int
+png_icc_profile_error(png_const_structrp png_ptr, png_colorspacerp colorspace,
+ png_const_charp name, png_alloc_size_t value, png_const_charp reason)
+{
+ size_t pos;
+ char message[196]; /* see below for calculation */
+
+ if (colorspace != NULL)
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+
+ pos = png_safecat(message, (sizeof message), 0, "profile '"); /* 9 chars */
+ pos = png_safecat(message, pos+79, pos, name); /* Truncate to 79 chars */
+ pos = png_safecat(message, (sizeof message), pos, "': "); /* +2 = 90 */
+ if (is_ICC_signature(value) != 0)
+ {
+ /* So 'value' is at most 4 bytes and the following cast is safe */
+ png_icc_tag_name(message+pos, (png_uint_32)value);
+ pos += 6; /* total +8; less than the else clause */
+ message[pos++] = ':';
+ message[pos++] = ' ';
+ }
+# ifdef PNG_WARNINGS_SUPPORTED
+ else
+ {
+ char number[PNG_NUMBER_BUFFER_SIZE]; /* +24 = 114*/
+
+ pos = png_safecat(message, (sizeof message), pos,
+ png_format_number(number, number+(sizeof number),
+ PNG_NUMBER_FORMAT_x, value));
+ pos = png_safecat(message, (sizeof message), pos, "h: "); /*+2 = 116*/
+ }
+# endif
+ /* The 'reason' is an arbitrary message, allow +79 maximum 195 */
+ pos = png_safecat(message, (sizeof message), pos, reason);
+ PNG_UNUSED(pos)
+
+ /* This is recoverable, but make it unconditionally an app_error on write to
+ * avoid writing invalid ICC profiles into PNG files (i.e., we handle them
+ * on read, with a warning, but on write unless the app turns off
+ * application errors the PNG won't be written.)
+ */
+ png_chunk_report(png_ptr, message,
+ (colorspace != NULL) ? PNG_CHUNK_ERROR : PNG_CHUNK_WRITE_ERROR);
+
+ return 0;
+}
+#endif /* sRGB || iCCP */
+
+#ifdef PNG_sRGB_SUPPORTED
+int /* PRIVATE */
+png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace,
+ int intent)
+{
+ /* sRGB sets known gamma, end points and (from the chunk) intent. */
+ /* IMPORTANT: these are not necessarily the values found in an ICC profile
+ * because ICC profiles store values adapted to a D50 environment; it is
+ * expected that the ICC profile mediaWhitePointTag will be D50; see the
+ * checks and code elsewhere to understand this better.
+ *
+ * These XYZ values, which are accurate to 5dp, produce rgb to gray
+ * coefficients of (6968,23435,2366), which are reduced (because they add up
+ * to 32769 not 32768) to (6968,23434,2366). These are the values that
+ * libpng has traditionally used (and are the best values given the 15bit
+ * algorithm used by the rgb to gray code.)
+ */
+ static const png_XYZ sRGB_XYZ = /* D65 XYZ (*not* the D50 adapted values!) */
+ {
+ /* color X Y Z */
+ /* red */ 41239, 21264, 1933,
+ /* green */ 35758, 71517, 11919,
+ /* blue */ 18048, 7219, 95053
+ };
+
+ /* Do nothing if the colorspace is already invalidated. */
+ if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
+ return 0;
+
+ /* Check the intent, then check for existing settings. It is valid for the
+ * PNG file to have cHRM or gAMA chunks along with sRGB, but the values must
+ * be consistent with the correct values. If, however, this function is
+ * called below because an iCCP chunk matches sRGB then it is quite
+ * conceivable that an older app recorded incorrect gAMA and cHRM because of
+ * an incorrect calculation based on the values in the profile - this does
+ * *not* invalidate the profile (though it still produces an error, which can
+ * be ignored.)
+ */
+ if (intent < 0 || intent >= PNG_sRGB_INTENT_LAST)
+ return png_icc_profile_error(png_ptr, colorspace, "sRGB",
+ (unsigned)intent, "invalid sRGB rendering intent");
+
+ if ((colorspace->flags & PNG_COLORSPACE_HAVE_INTENT) != 0 &&
+ colorspace->rendering_intent != intent)
+ return png_icc_profile_error(png_ptr, colorspace, "sRGB",
+ (unsigned)intent, "inconsistent rendering intents");
+
+ if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0)
+ {
+ png_benign_error(png_ptr, "duplicate sRGB information ignored");
+ return 0;
+ }
+
+ /* If the standard sRGB cHRM chunk does not match the one from the PNG file
+ * warn but overwrite the value with the correct one.
+ */
+ if ((colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0 &&
+ !png_colorspace_endpoints_match(&sRGB_xy, &colorspace->end_points_xy,
+ 100))
+ png_chunk_report(png_ptr, "cHRM chunk does not match sRGB",
+ PNG_CHUNK_ERROR);
+
+ /* This check is just done for the error reporting - the routine always
+ * returns true when the 'from' argument corresponds to sRGB (2).
+ */
+ (void)png_colorspace_check_gamma(png_ptr, colorspace, PNG_GAMMA_sRGB_INVERSE,
+ 2/*from sRGB*/);
+
+ /* intent: bugs in GCC force 'int' to be used as the parameter type. */
+ colorspace->rendering_intent = (png_uint_16)intent;
+ colorspace->flags |= PNG_COLORSPACE_HAVE_INTENT;
+
+ /* endpoints */
+ colorspace->end_points_xy = sRGB_xy;
+ colorspace->end_points_XYZ = sRGB_XYZ;
+ colorspace->flags |=
+ (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
+
+ /* gamma */
+ colorspace->gamma = PNG_GAMMA_sRGB_INVERSE;
+ colorspace->flags |= PNG_COLORSPACE_HAVE_GAMMA;
+
+ /* Finally record that we have an sRGB profile */
+ colorspace->flags |=
+ (PNG_COLORSPACE_MATCHES_sRGB|PNG_COLORSPACE_FROM_sRGB);
+
+ return 1; /* set */
+}
+#endif /* sRGB */
+
+#ifdef PNG_iCCP_SUPPORTED
+/* Encoded value of D50 as an ICC XYZNumber. From the ICC 2010 spec the value
+ * is XYZ(0.9642,1.0,0.8249), which scales to:
+ *
+ * (63189.8112, 65536, 54060.6464)
+ */
+static const png_byte D50_nCIEXYZ[12] =
+ { 0x00, 0x00, 0xf6, 0xd6, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0xd3, 0x2d };
+
+int /* PRIVATE */
+png_icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
+ png_const_charp name, png_uint_32 profile_length)
+{
+ if (profile_length < 132)
+ return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
+ "too short");
+
+ return 1;
+}
+
+int /* PRIVATE */
+png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
+ png_const_charp name, png_uint_32 profile_length,
+ png_const_bytep profile/* first 132 bytes only */, int color_type)
+{
+ png_uint_32 temp;
+
+ /* Length check; this cannot be ignored in this code because profile_length
+ * is used later to check the tag table, so even if the profile seems over
+ * long profile_length from the caller must be correct. The caller can fix
+ * this up on read or write by just passing in the profile header length.
+ */
+ temp = png_get_uint_32(profile);
+ if (temp != profile_length)
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "length does not match profile");
+
+ temp = (png_uint_32) (*(profile+8));
+ if (temp > 3 && (profile_length & 3))
+ return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
+ "invalid length");
+
+ temp = png_get_uint_32(profile+128); /* tag count: 12 bytes/tag */
+ if (temp > 357913930 || /* (2^32-4-132)/12: maximum possible tag count */
+ profile_length < 132+12*temp) /* truncated tag table */
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "tag count too large");
+
+ /* The 'intent' must be valid or we can't store it, ICC limits the intent to
+ * 16 bits.
+ */
+ temp = png_get_uint_32(profile+64);
+ if (temp >= 0xffff) /* The ICC limit */
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "invalid rendering intent");
+
+ /* This is just a warning because the profile may be valid in future
+ * versions.
+ */
+ if (temp >= PNG_sRGB_INTENT_LAST)
+ (void)png_icc_profile_error(png_ptr, NULL, name, temp,
+ "intent outside defined range");
+
+ /* At this point the tag table can't be checked because it hasn't necessarily
+ * been loaded; however, various header fields can be checked. These checks
+ * are for values permitted by the PNG spec in an ICC profile; the PNG spec
+ * restricts the profiles that can be passed in an iCCP chunk (they must be
+ * appropriate to processing PNG data!)
+ */
+
+ /* Data checks (could be skipped). These checks must be independent of the
+ * version number; however, the version number doesn't accomodate changes in
+ * the header fields (just the known tags and the interpretation of the
+ * data.)
+ */
+ temp = png_get_uint_32(profile+36); /* signature 'ascp' */
+ if (temp != 0x61637370)
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "invalid signature");
+
+ /* Currently the PCS illuminant/adopted white point (the computational
+ * white point) are required to be D50,
+ * however the profile contains a record of the illuminant so perhaps ICC
+ * expects to be able to change this in the future (despite the rationale in
+ * the introduction for using a fixed PCS adopted white.) Consequently the
+ * following is just a warning.
+ */
+ if (memcmp(profile+68, D50_nCIEXYZ, 12) != 0)
+ (void)png_icc_profile_error(png_ptr, NULL, name, 0/*no tag value*/,
+ "PCS illuminant is not D50");
+
+ /* The PNG spec requires this:
+ * "If the iCCP chunk is present, the image samples conform to the colour
+ * space represented by the embedded ICC profile as defined by the
+ * International Color Consortium [ICC]. The colour space of the ICC profile
+ * shall be an RGB colour space for colour images (PNG colour types 2, 3, and
+ * 6), or a greyscale colour space for greyscale images (PNG colour types 0
+ * and 4)."
+ *
+ * This checking code ensures the embedded profile (on either read or write)
+ * conforms to the specification requirements. Notice that an ICC 'gray'
+ * color-space profile contains the information to transform the monochrome
+ * data to XYZ or L*a*b (according to which PCS the profile uses) and this
+ * should be used in preference to the standard libpng K channel replication
+ * into R, G and B channels.
+ *
+ * Previously it was suggested that an RGB profile on grayscale data could be
+ * handled. However it it is clear that using an RGB profile in this context
+ * must be an error - there is no specification of what it means. Thus it is
+ * almost certainly more correct to ignore the profile.
+ */
+ temp = png_get_uint_32(profile+16); /* data colour space field */
+ switch (temp)
+ {
+ case 0x52474220: /* 'RGB ' */
+ if ((color_type & PNG_COLOR_MASK_COLOR) == 0)
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "RGB color space not permitted on grayscale PNG");
+ break;
+
+ case 0x47524159: /* 'GRAY' */
+ if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "Gray color space not permitted on RGB PNG");
+ break;
+
+ default:
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "invalid ICC profile color space");
+ }
+
+ /* It is up to the application to check that the profile class matches the
+ * application requirements; the spec provides no guidance, but it's pretty
+ * weird if the profile is not scanner ('scnr'), monitor ('mntr'), printer
+ * ('prtr') or 'spac' (for generic color spaces). Issue a warning in these
+ * cases. Issue an error for device link or abstract profiles - these don't
+ * contain the records necessary to transform the color-space to anything
+ * other than the target device (and not even that for an abstract profile).
+ * Profiles of these classes may not be embedded in images.
+ */
+ temp = png_get_uint_32(profile+12); /* profile/device class */
+ switch (temp)
+ {
+ case 0x73636e72: /* 'scnr' */
+ case 0x6d6e7472: /* 'mntr' */
+ case 0x70727472: /* 'prtr' */
+ case 0x73706163: /* 'spac' */
+ /* All supported */
+ break;
+
+ case 0x61627374: /* 'abst' */
+ /* May not be embedded in an image */
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "invalid embedded Abstract ICC profile");
+
+ case 0x6c696e6b: /* 'link' */
+ /* DeviceLink profiles cannot be interpreted in a non-device specific
+ * fashion, if an app uses the AToB0Tag in the profile the results are
+ * undefined unless the result is sent to the intended device,
+ * therefore a DeviceLink profile should not be found embedded in a
+ * PNG.
+ */
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "unexpected DeviceLink ICC profile class");
+
+ case 0x6e6d636c: /* 'nmcl' */
+ /* A NamedColor profile is also device specific, however it doesn't
+ * contain an AToB0 tag that is open to misinterpretation. Almost
+ * certainly it will fail the tests below.
+ */
+ (void)png_icc_profile_error(png_ptr, NULL, name, temp,
+ "unexpected NamedColor ICC profile class");
+ break;
+
+ default:
+ /* To allow for future enhancements to the profile accept unrecognized
+ * profile classes with a warning, these then hit the test below on the
+ * tag content to ensure they are backward compatible with one of the
+ * understood profiles.
+ */
+ (void)png_icc_profile_error(png_ptr, NULL, name, temp,
+ "unrecognized ICC profile class");
+ break;
+ }
+
+ /* For any profile other than a device link one the PCS must be encoded
+ * either in XYZ or Lab.
+ */
+ temp = png_get_uint_32(profile+20);
+ switch (temp)
+ {
+ case 0x58595a20: /* 'XYZ ' */
+ case 0x4c616220: /* 'Lab ' */
+ break;
+
+ default:
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "unexpected ICC PCS encoding");
+ }
+
+ return 1;
+}
+
+int /* PRIVATE */
+png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace,
+ png_const_charp name, png_uint_32 profile_length,
+ png_const_bytep profile /* header plus whole tag table */)
+{
+ png_uint_32 tag_count = png_get_uint_32(profile+128);
+ png_uint_32 itag;
+ png_const_bytep tag = profile+132; /* The first tag */
+
+ /* First scan all the tags in the table and add bits to the icc_info value
+ * (temporarily in 'tags').
+ */
+ for (itag=0; itag < tag_count; ++itag, tag += 12)
+ {
+ png_uint_32 tag_id = png_get_uint_32(tag+0);
+ png_uint_32 tag_start = png_get_uint_32(tag+4); /* must be aligned */
+ png_uint_32 tag_length = png_get_uint_32(tag+8);/* not padded */
+
+ /* The ICC specification does not exclude zero length tags, therefore the
+ * start might actually be anywhere if there is no data, but this would be
+ * a clear abuse of the intent of the standard so the start is checked for
+ * being in range. All defined tag types have an 8 byte header - a 4 byte
+ * type signature then 0.
+ */
+ if ((tag_start & 3) != 0)
+ {
+ /* CNHP730S.icc shipped with Microsoft Windows 64 violates this, it is
+ * only a warning here because libpng does not care about the
+ * alignment.
+ */
+ (void)png_icc_profile_error(png_ptr, NULL, name, tag_id,
+ "ICC profile tag start not a multiple of 4");
+ }
+
+ /* This is a hard error; potentially it can cause read outside the
+ * profile.
+ */
+ if (tag_start > profile_length || tag_length > profile_length - tag_start)
+ return png_icc_profile_error(png_ptr, colorspace, name, tag_id,
+ "ICC profile tag outside profile");
+ }
+
+ return 1; /* success, maybe with warnings */
+}
+
+#ifdef PNG_sRGB_SUPPORTED
+#if PNG_sRGB_PROFILE_CHECKS >= 0
+/* Information about the known ICC sRGB profiles */
+static const struct
+{
+ png_uint_32 adler, crc, length;
+ png_uint_32 md5[4];
+ png_byte have_md5;
+ png_byte is_broken;
+ png_uint_16 intent;
+
+# define PNG_MD5(a,b,c,d) { a, b, c, d }, (a!=0)||(b!=0)||(c!=0)||(d!=0)
+# define PNG_ICC_CHECKSUM(adler, crc, md5, intent, broke, date, length, fname)\
+ { adler, crc, length, md5, broke, intent },
+
+} png_sRGB_checks[] =
+{
+ /* This data comes from contrib/tools/checksum-icc run on downloads of
+ * all four ICC sRGB profiles from www.color.org.
+ */
+ /* adler32, crc32, MD5[4], intent, date, length, file-name */
+ PNG_ICC_CHECKSUM(0x0a3fd9f6, 0x3b8772b9,
+ PNG_MD5(0x29f83dde, 0xaff255ae, 0x7842fae4, 0xca83390d), 0, 0,
+ "2009/03/27 21:36:31", 3048, "sRGB_IEC61966-2-1_black_scaled.icc")
+
+ /* ICC sRGB v2 perceptual no black-compensation: */
+ PNG_ICC_CHECKSUM(0x4909e5e1, 0x427ebb21,
+ PNG_MD5(0xc95bd637, 0xe95d8a3b, 0x0df38f99, 0xc1320389), 1, 0,
+ "2009/03/27 21:37:45", 3052, "sRGB_IEC61966-2-1_no_black_scaling.icc")
+
+ PNG_ICC_CHECKSUM(0xfd2144a1, 0x306fd8ae,
+ PNG_MD5(0xfc663378, 0x37e2886b, 0xfd72e983, 0x8228f1b8), 0, 0,
+ "2009/08/10 17:28:01", 60988, "sRGB_v4_ICC_preference_displayclass.icc")
+
+ /* ICC sRGB v4 perceptual */
+ PNG_ICC_CHECKSUM(0x209c35d2, 0xbbef7812,
+ PNG_MD5(0x34562abf, 0x994ccd06, 0x6d2c5721, 0xd0d68c5d), 0, 0,
+ "2007/07/25 00:05:37", 60960, "sRGB_v4_ICC_preference.icc")
+
+ /* The following profiles have no known MD5 checksum. If there is a match
+ * on the (empty) MD5 the other fields are used to attempt a match and
+ * a warning is produced. The first two of these profiles have a 'cprt' tag
+ * which suggests that they were also made by Hewlett Packard.
+ */
+ PNG_ICC_CHECKSUM(0xa054d762, 0x5d5129ce,
+ PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 0,
+ "2004/07/21 18:57:42", 3024, "sRGB_IEC61966-2-1_noBPC.icc")
+
+ /* This is a 'mntr' (display) profile with a mediaWhitePointTag that does not
+ * match the D50 PCS illuminant in the header (it is in fact the D65 values,
+ * so the white point is recorded as the un-adapted value.) The profiles
+ * below only differ in one byte - the intent - and are basically the same as
+ * the previous profile except for the mediaWhitePointTag error and a missing
+ * chromaticAdaptationTag.
+ */
+ PNG_ICC_CHECKSUM(0xf784f3fb, 0x182ea552,
+ PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 0, 1/*broken*/,
+ "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 perceptual")
+
+ PNG_ICC_CHECKSUM(0x0398f3fc, 0xf29e526d,
+ PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 1/*broken*/,
+ "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 media-relative")
+};
+
+static int
+png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,
+ png_const_bytep profile, uLong adler)
+{
+ /* The quick check is to verify just the MD5 signature and trust the
+ * rest of the data. Because the profile has already been verified for
+ * correctness this is safe. png_colorspace_set_sRGB will check the 'intent'
+ * field too, so if the profile has been edited with an intent not defined
+ * by sRGB (but maybe defined by a later ICC specification) the read of
+ * the profile will fail at that point.
+ */
+
+ png_uint_32 length = 0;
+ png_uint_32 intent = 0x10000; /* invalid */
+#if PNG_sRGB_PROFILE_CHECKS > 1
+ uLong crc = 0; /* the value for 0 length data */
+#endif
+ unsigned int i;
+
+#ifdef PNG_SET_OPTION_SUPPORTED
+ /* First see if PNG_SKIP_sRGB_CHECK_PROFILE has been set to "on" */
+ if (((png_ptr->options >> PNG_SKIP_sRGB_CHECK_PROFILE) & 3) ==
+ PNG_OPTION_ON)
+ return 0;
+#endif
+
+ for (i=0; i < (sizeof png_sRGB_checks) / (sizeof png_sRGB_checks[0]); ++i)
+ {
+ if (png_get_uint_32(profile+84) == png_sRGB_checks[i].md5[0] &&
+ png_get_uint_32(profile+88) == png_sRGB_checks[i].md5[1] &&
+ png_get_uint_32(profile+92) == png_sRGB_checks[i].md5[2] &&
+ png_get_uint_32(profile+96) == png_sRGB_checks[i].md5[3])
+ {
+ /* This may be one of the old HP profiles without an MD5, in that
+ * case we can only use the length and Adler32 (note that these
+ * are not used by default if there is an MD5!)
+ */
+# if PNG_sRGB_PROFILE_CHECKS == 0
+ if (png_sRGB_checks[i].have_md5 != 0)
+ return 1+png_sRGB_checks[i].is_broken;
+# endif
+
+ /* Profile is unsigned or more checks have been configured in. */
+ if (length == 0)
+ {
+ length = png_get_uint_32(profile);
+ intent = png_get_uint_32(profile+64);
+ }
+
+ /* Length *and* intent must match */
+ if (length == (png_uint_32) png_sRGB_checks[i].length &&
+ intent == (png_uint_32) png_sRGB_checks[i].intent)
+ {
+ /* Now calculate the adler32 if not done already. */
+ if (adler == 0)
+ {
+ adler = adler32(0, NULL, 0);
+ adler = adler32(adler, profile, length);
+ }
+
+ if (adler == png_sRGB_checks[i].adler)
+ {
+ /* These basic checks suggest that the data has not been
+ * modified, but if the check level is more than 1 perform
+ * our own crc32 checksum on the data.
+ */
+# if PNG_sRGB_PROFILE_CHECKS > 1
+ if (crc == 0)
+ {
+ crc = crc32(0, NULL, 0);
+ crc = crc32(crc, profile, length);
+ }
+
+ /* So this check must pass for the 'return' below to happen.
+ */
+ if (crc == png_sRGB_checks[i].crc)
+# endif
+ {
+ if (png_sRGB_checks[i].is_broken != 0)
+ {
+ /* These profiles are known to have bad data that may cause
+ * problems if they are used, therefore attempt to
+ * discourage their use, skip the 'have_md5' warning below,
+ * which is made irrelevant by this error.
+ */
+ png_chunk_report(png_ptr, "known incorrect sRGB profile",
+ PNG_CHUNK_ERROR);
+ }
+
+ /* Warn that this being done; this isn't even an error since
+ * the profile is perfectly valid, but it would be nice if
+ * people used the up-to-date ones.
+ */
+ else if (png_sRGB_checks[i].have_md5 == 0)
+ {
+ png_chunk_report(png_ptr,
+ "out-of-date sRGB profile with no signature",
+ PNG_CHUNK_WARNING);
+ }
+
+ return 1+png_sRGB_checks[i].is_broken;
+ }
+ }
+
+# if PNG_sRGB_PROFILE_CHECKS > 0
+ /* The signature matched, but the profile had been changed in some
+ * way. This probably indicates a data error or uninformed hacking.
+ * Fall through to "no match".
+ */
+ png_chunk_report(png_ptr,
+ "Not recognizing known sRGB profile that has been edited",
+ PNG_CHUNK_WARNING);
+ break;
+# endif
+ }
+ }
+ }
+
+ return 0; /* no match */
+}
+#endif /* PNG_sRGB_PROFILE_CHECKS >= 0 */
+
+void /* PRIVATE */
+png_icc_set_sRGB(png_const_structrp png_ptr,
+ png_colorspacerp colorspace, png_const_bytep profile, uLong adler)
+{
+ /* Is this profile one of the known ICC sRGB profiles? If it is, just set
+ * the sRGB information.
+ */
+#if PNG_sRGB_PROFILE_CHECKS >= 0
+ if (png_compare_ICC_profile_with_sRGB(png_ptr, profile, adler) != 0)
+#endif
+ (void)png_colorspace_set_sRGB(png_ptr, colorspace,
+ (int)/*already checked*/png_get_uint_32(profile+64));
+}
+#endif /* sRGB */
+
+int /* PRIVATE */
+png_colorspace_set_ICC(png_const_structrp png_ptr, png_colorspacerp colorspace,
+ png_const_charp name, png_uint_32 profile_length, png_const_bytep profile,
+ int color_type)
+{
+ if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
+ return 0;
+
+ if (png_icc_check_length(png_ptr, colorspace, name, profile_length) != 0 &&
+ png_icc_check_header(png_ptr, colorspace, name, profile_length, profile,
+ color_type) != 0 &&
+ png_icc_check_tag_table(png_ptr, colorspace, name, profile_length,
+ profile) != 0)
+ {
+# ifdef PNG_sRGB_SUPPORTED
+ /* If no sRGB support, don't try storing sRGB information */
+ png_icc_set_sRGB(png_ptr, colorspace, profile, 0);
+# endif
+ return 1;
+ }
+
+ /* Failure case */
+ return 0;
+}
+#endif /* iCCP */
+
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+void /* PRIVATE */
+png_colorspace_set_rgb_coefficients(png_structrp png_ptr)
+{
+ /* Set the rgb_to_gray coefficients from the colorspace. */
+ if (png_ptr->rgb_to_gray_coefficients_set == 0 &&
+ (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
+ {
+ /* png_set_background has not been called, get the coefficients from the Y
+ * values of the colorspace colorants.
+ */
+ png_fixed_point r = png_ptr->colorspace.end_points_XYZ.red_Y;
+ png_fixed_point g = png_ptr->colorspace.end_points_XYZ.green_Y;
+ png_fixed_point b = png_ptr->colorspace.end_points_XYZ.blue_Y;
+ png_fixed_point total = r+g+b;
+
+ if (total > 0 &&
+ r >= 0 && png_muldiv(&r, r, 32768, total) && r >= 0 && r <= 32768 &&
+ g >= 0 && png_muldiv(&g, g, 32768, total) && g >= 0 && g <= 32768 &&
+ b >= 0 && png_muldiv(&b, b, 32768, total) && b >= 0 && b <= 32768 &&
+ r+g+b <= 32769)
+ {
+ /* We allow 0 coefficients here. r+g+b may be 32769 if two or
+ * all of the coefficients were rounded up. Handle this by
+ * reducing the *largest* coefficient by 1; this matches the
+ * approach used for the default coefficients in pngrtran.c
+ */
+ int add = 0;
+
+ if (r+g+b > 32768)
+ add = -1;
+ else if (r+g+b < 32768)
+ add = 1;
+
+ if (add != 0)
+ {
+ if (g >= r && g >= b)
+ g += add;
+ else if (r >= g && r >= b)
+ r += add;
+ else
+ b += add;
+ }
+
+ /* Check for an internal error. */
+ if (r+g+b != 32768)
+ png_error(png_ptr,
+ "internal error handling cHRM coefficients");
+
+ else
+ {
+ png_ptr->rgb_to_gray_red_coeff = (png_uint_16)r;
+ png_ptr->rgb_to_gray_green_coeff = (png_uint_16)g;
+ }
+ }
+
+ /* This is a png_error at present even though it could be ignored -
+ * it should never happen, but it is important that if it does, the
+ * bug is fixed.
+ */
+ else
+ png_error(png_ptr, "internal error handling cHRM->XYZ");
+ }
+}
+#endif /* READ_RGB_TO_GRAY */
+
+#endif /* COLORSPACE */
+
+#ifdef __GNUC__
+/* This exists solely to work round a warning from GNU C. */
+static int /* PRIVATE */
+png_gt(size_t a, size_t b)
+{
+ return a > b;
+}
+#else
+# define png_gt(a,b) ((a) > (b))
+#endif
+
+void /* PRIVATE */
+png_check_IHDR(png_const_structrp png_ptr,
+ png_uint_32 width, png_uint_32 height, int bit_depth,
+ int color_type, int interlace_type, int compression_type,
+ int filter_type)
+{
+ int error = 0;
+
+ /* Check for width and height valid values */
+ if (width == 0)
+ {
+ png_warning(png_ptr, "Image width is zero in IHDR");
+ error = 1;
+ }
+
+ if (width > PNG_UINT_31_MAX)
+ {
+ png_warning(png_ptr, "Invalid image width in IHDR");
+ error = 1;
+ }
+
+ if (png_gt(((width + 7) & (~7)),
+ ((PNG_SIZE_MAX
+ - 48 /* big_row_buf hack */
+ - 1) /* filter byte */
+ / 8) /* 8-byte RGBA pixels */
+ - 1)) /* extra max_pixel_depth pad */
+ {
+ /* The size of the row must be within the limits of this architecture.
+ * Because the read code can perform arbitrary transformations the
+ * maximum size is checked here. Because the code in png_read_start_row
+ * adds extra space "for safety's sake" in several places a conservative
+ * limit is used here.
+ *
+ * NOTE: it would be far better to check the size that is actually used,
+ * but the effect in the real world is minor and the changes are more
+ * extensive, therefore much more dangerous and much more difficult to
+ * write in a way that avoids compiler warnings.
+ */
+ png_warning(png_ptr, "Image width is too large for this architecture");
+ error = 1;
+ }
+
+#ifdef PNG_SET_USER_LIMITS_SUPPORTED
+ if (width > png_ptr->user_width_max)
+#else
+ if (width > PNG_USER_WIDTH_MAX)
+#endif
+ {
+ png_warning(png_ptr, "Image width exceeds user limit in IHDR");
+ error = 1;
+ }
+
+ if (height == 0)
+ {
+ png_warning(png_ptr, "Image height is zero in IHDR");
+ error = 1;
+ }
+
+ if (height > PNG_UINT_31_MAX)
+ {
+ png_warning(png_ptr, "Invalid image height in IHDR");
+ error = 1;
+ }
+
+#ifdef PNG_SET_USER_LIMITS_SUPPORTED
+ if (height > png_ptr->user_height_max)
+#else
+ if (height > PNG_USER_HEIGHT_MAX)
+#endif
+ {
+ png_warning(png_ptr, "Image height exceeds user limit in IHDR");
+ error = 1;
+ }
+
+ /* Check other values */
+ if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 &&
+ bit_depth != 8 && bit_depth != 16)
+ {
+ png_warning(png_ptr, "Invalid bit depth in IHDR");
+ error = 1;
+ }
+
+ if (color_type < 0 || color_type == 1 ||
+ color_type == 5 || color_type > 6)
+ {
+ png_warning(png_ptr, "Invalid color type in IHDR");
+ error = 1;
+ }
+
+ if (((color_type == PNG_COLOR_TYPE_PALETTE) && bit_depth > 8) ||
+ ((color_type == PNG_COLOR_TYPE_RGB ||
+ color_type == PNG_COLOR_TYPE_GRAY_ALPHA ||
+ color_type == PNG_COLOR_TYPE_RGB_ALPHA) && bit_depth < 8))
+ {
+ png_warning(png_ptr, "Invalid color type/bit depth combination in IHDR");
+ error = 1;
+ }
+
+ if (interlace_type >= PNG_INTERLACE_LAST)
+ {
+ png_warning(png_ptr, "Unknown interlace method in IHDR");
+ error = 1;
+ }
+
+ if (compression_type != PNG_COMPRESSION_TYPE_BASE)
+ {
+ png_warning(png_ptr, "Unknown compression method in IHDR");
+ error = 1;
+ }
+
+#ifdef PNG_MNG_FEATURES_SUPPORTED
+ /* Accept filter_method 64 (intrapixel differencing) only if
+ * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
+ * 2. Libpng did not read a PNG signature (this filter_method is only
+ * used in PNG datastreams that are embedded in MNG datastreams) and
+ * 3. The application called png_permit_mng_features with a mask that
+ * included PNG_FLAG_MNG_FILTER_64 and
+ * 4. The filter_method is 64 and
+ * 5. The color_type is RGB or RGBA
+ */
+ if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0 &&
+ png_ptr->mng_features_permitted != 0)
+ png_warning(png_ptr, "MNG features are not allowed in a PNG datastream");
+
+ if (filter_type != PNG_FILTER_TYPE_BASE)
+ {
+ if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
+ (filter_type == PNG_INTRAPIXEL_DIFFERENCING) &&
+ ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
+ (color_type == PNG_COLOR_TYPE_RGB ||
+ color_type == PNG_COLOR_TYPE_RGB_ALPHA)))
+ {
+ png_warning(png_ptr, "Unknown filter method in IHDR");
+ error = 1;
+ }
+
+ if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0)
+ {
+ png_warning(png_ptr, "Invalid filter method in IHDR");
+ error = 1;
+ }
+ }
+
+#else
+ if (filter_type != PNG_FILTER_TYPE_BASE)
+ {
+ png_warning(png_ptr, "Unknown filter method in IHDR");
+ error = 1;
+ }
+#endif
+
+ if (error == 1)
+ png_error(png_ptr, "Invalid IHDR data");
+}
+
+#if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED)
+/* ASCII to fp functions */
+/* Check an ASCII formated floating point value, see the more detailed
+ * comments in pngpriv.h
+ */
+/* The following is used internally to preserve the sticky flags */
+#define png_fp_add(state, flags) ((state) |= (flags))
+#define png_fp_set(state, value) ((state) = (value) | ((state) & PNG_FP_STICKY))
+
+int /* PRIVATE */
+png_check_fp_number(png_const_charp string, png_size_t size, int *statep,
+ png_size_tp whereami)
+{
+ int state = *statep;
+ png_size_t i = *whereami;
+
+ while (i < size)
+ {
+ int type;
+ /* First find the type of the next character */
+ switch (string[i])
+ {
+ case 43: type = PNG_FP_SAW_SIGN; break;
+ case 45: type = PNG_FP_SAW_SIGN + PNG_FP_NEGATIVE; break;
+ case 46: type = PNG_FP_SAW_DOT; break;
+ case 48: type = PNG_FP_SAW_DIGIT; break;
+ case 49: case 50: case 51: case 52:
+ case 53: case 54: case 55: case 56:
+ case 57: type = PNG_FP_SAW_DIGIT + PNG_FP_NONZERO; break;
+ case 69:
+ case 101: type = PNG_FP_SAW_E; break;
+ default: goto PNG_FP_End;
+ }
+
+ /* Now deal with this type according to the current
+ * state, the type is arranged to not overlap the
+ * bits of the PNG_FP_STATE.
+ */
+ switch ((state & PNG_FP_STATE) + (type & PNG_FP_SAW_ANY))
+ {
+ case PNG_FP_INTEGER + PNG_FP_SAW_SIGN:
+ if ((state & PNG_FP_SAW_ANY) != 0)
+ goto PNG_FP_End; /* not a part of the number */
+
+ png_fp_add(state, type);
+ break;
+
+ case PNG_FP_INTEGER + PNG_FP_SAW_DOT:
+ /* Ok as trailer, ok as lead of fraction. */
+ if ((state & PNG_FP_SAW_DOT) != 0) /* two dots */
+ goto PNG_FP_End;
+
+ else if ((state & PNG_FP_SAW_DIGIT) != 0) /* trailing dot? */
+ png_fp_add(state, type);
+
+ else
+ png_fp_set(state, PNG_FP_FRACTION | type);
+
+ break;
+
+ case PNG_FP_INTEGER + PNG_FP_SAW_DIGIT:
+ if ((state & PNG_FP_SAW_DOT) != 0) /* delayed fraction */
+ png_fp_set(state, PNG_FP_FRACTION | PNG_FP_SAW_DOT);
+
+ png_fp_add(state, type | PNG_FP_WAS_VALID);
+
+ break;
+
+ case PNG_FP_INTEGER + PNG_FP_SAW_E:
+ if ((state & PNG_FP_SAW_DIGIT) == 0)
+ goto PNG_FP_End;
+
+ png_fp_set(state, PNG_FP_EXPONENT);
+
+ break;
+
+ /* case PNG_FP_FRACTION + PNG_FP_SAW_SIGN:
+ goto PNG_FP_End; ** no sign in fraction */
+
+ /* case PNG_FP_FRACTION + PNG_FP_SAW_DOT:
+ goto PNG_FP_End; ** Because SAW_DOT is always set */
+
+ case PNG_FP_FRACTION + PNG_FP_SAW_DIGIT:
+ png_fp_add(state, type | PNG_FP_WAS_VALID);
+ break;
+
+ case PNG_FP_FRACTION + PNG_FP_SAW_E:
+ /* This is correct because the trailing '.' on an
+ * integer is handled above - so we can only get here
+ * with the sequence ".E" (with no preceding digits).
+ */
+ if ((state & PNG_FP_SAW_DIGIT) == 0)
+ goto PNG_FP_End;
+
+ png_fp_set(state, PNG_FP_EXPONENT);
+
+ break;
+
+ case PNG_FP_EXPONENT + PNG_FP_SAW_SIGN:
+ if ((state & PNG_FP_SAW_ANY) != 0)
+ goto PNG_FP_End; /* not a part of the number */
+
+ png_fp_add(state, PNG_FP_SAW_SIGN);
+
+ break;
+
+ /* case PNG_FP_EXPONENT + PNG_FP_SAW_DOT:
+ goto PNG_FP_End; */
+
+ case PNG_FP_EXPONENT + PNG_FP_SAW_DIGIT:
+ png_fp_add(state, PNG_FP_SAW_DIGIT | PNG_FP_WAS_VALID);
+
+ break;
+
+ /* case PNG_FP_EXPONEXT + PNG_FP_SAW_E:
+ goto PNG_FP_End; */
+
+ default: goto PNG_FP_End; /* I.e. break 2 */
+ }
+
+ /* The character seems ok, continue. */
+ ++i;
+ }
+
+PNG_FP_End:
+ /* Here at the end, update the state and return the correct
+ * return code.
+ */
+ *statep = state;
+ *whereami = i;
+
+ return (state & PNG_FP_SAW_DIGIT) != 0;
+}
+
+
+/* The same but for a complete string. */
+int
+png_check_fp_string(png_const_charp string, png_size_t size)
+{
+ int state=0;
+ png_size_t char_index=0;
+
+ if (png_check_fp_number(string, size, &state, &char_index) != 0 &&
+ (char_index == size || string[char_index] == 0))
+ return state /* must be non-zero - see above */;
+
+ return 0; /* i.e. fail */
+}
+#endif /* pCAL || sCAL */
+
+#ifdef PNG_sCAL_SUPPORTED
+# ifdef PNG_FLOATING_POINT_SUPPORTED
+/* Utility used below - a simple accurate power of ten from an integral
+ * exponent.
+ */
+static double
+png_pow10(int power)
+{
+ int recip = 0;
+ double d = 1;
+
+ /* Handle negative exponent with a reciprocal at the end because
+ * 10 is exact whereas .1 is inexact in base 2
+ */
+ if (power < 0)
+ {
+ if (power < DBL_MIN_10_EXP) return 0;
+ recip = 1, power = -power;
+ }
+
+ if (power > 0)
+ {
+ /* Decompose power bitwise. */
+ double mult = 10;
+ do
+ {
+ if (power & 1) d *= mult;
+ mult *= mult;
+ power >>= 1;
+ }
+ while (power > 0);
+
+ if (recip != 0) d = 1/d;
+ }
+ /* else power is 0 and d is 1 */
+
+ return d;
+}
+
+/* Function to format a floating point value in ASCII with a given
+ * precision.
+ */
+void /* PRIVATE */
+png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
+ double fp, unsigned int precision)
+{
+ /* We use standard functions from math.h, but not printf because
+ * that would require stdio. The caller must supply a buffer of
+ * sufficient size or we will png_error. The tests on size and
+ * the space in ascii[] consumed are indicated below.
+ */
+ if (precision < 1)
+ precision = DBL_DIG;
+
+ /* Enforce the limit of the implementation precision too. */
+ if (precision > DBL_DIG+1)
+ precision = DBL_DIG+1;
+
+ /* Basic sanity checks */
+ if (size >= precision+5) /* See the requirements below. */
+ {
+ if (fp < 0)
+ {
+ fp = -fp;
+ *ascii++ = 45; /* '-' PLUS 1 TOTAL 1 */
+ --size;
+ }
+
+ if (fp >= DBL_MIN && fp <= DBL_MAX)
+ {
+ int exp_b10; /* A base 10 exponent */
+ double base; /* 10^exp_b10 */
+
+ /* First extract a base 10 exponent of the number,
+ * the calculation below rounds down when converting
+ * from base 2 to base 10 (multiply by log10(2) -
+ * 0.3010, but 77/256 is 0.3008, so exp_b10 needs to
+ * be increased. Note that the arithmetic shift
+ * performs a floor() unlike C arithmetic - using a
+ * C multiply would break the following for negative
+ * exponents.
+ */
+ (void)frexp(fp, &exp_b10); /* exponent to base 2 */
+
+ exp_b10 = (exp_b10 * 77) >> 8; /* <= exponent to base 10 */
+
+ /* Avoid underflow here. */
+ base = png_pow10(exp_b10); /* May underflow */
+
+ while (base < DBL_MIN || base < fp)
+ {
+ /* And this may overflow. */
+ double test = png_pow10(exp_b10+1);
+
+ if (test <= DBL_MAX)
+ ++exp_b10, base = test;
+
+ else
+ break;
+ }
+
+ /* Normalize fp and correct exp_b10, after this fp is in the
+ * range [.1,1) and exp_b10 is both the exponent and the digit
+ * *before* which the decimal point should be inserted
+ * (starting with 0 for the first digit). Note that this
+ * works even if 10^exp_b10 is out of range because of the
+ * test on DBL_MAX above.
+ */
+ fp /= base;
+ while (fp >= 1) fp /= 10, ++exp_b10;
+
+ /* Because of the code above fp may, at this point, be
+ * less than .1, this is ok because the code below can
+ * handle the leading zeros this generates, so no attempt
+ * is made to correct that here.
+ */
+
+ {
+ unsigned int czero, clead, cdigits;
+ char exponent[10];
+
+ /* Allow up to two leading zeros - this will not lengthen
+ * the number compared to using E-n.
+ */
+ if (exp_b10 < 0 && exp_b10 > -3) /* PLUS 3 TOTAL 4 */
+ {
+ czero = -exp_b10; /* PLUS 2 digits: TOTAL 3 */
+ exp_b10 = 0; /* Dot added below before first output. */
+ }
+ else
+ czero = 0; /* No zeros to add */
+
+ /* Generate the digit list, stripping trailing zeros and
+ * inserting a '.' before a digit if the exponent is 0.
+ */
+ clead = czero; /* Count of leading zeros */
+ cdigits = 0; /* Count of digits in list. */
+
+ do
+ {
+ double d;
+
+ fp *= 10;
+ /* Use modf here, not floor and subtract, so that
+ * the separation is done in one step. At the end
+ * of the loop don't break the number into parts so
+ * that the final digit is rounded.
+ */
+ if (cdigits+czero+1 < precision+clead)
+ fp = modf(fp, &d);
+
+ else
+ {
+ d = floor(fp + .5);
+
+ if (d > 9)
+ {
+ /* Rounding up to 10, handle that here. */
+ if (czero > 0)
+ {
+ --czero, d = 1;
+ if (cdigits == 0) --clead;
+ }
+ else
+ {
+ while (cdigits > 0 && d > 9)
+ {
+ int ch = *--ascii;
+
+ if (exp_b10 != (-1))
+ ++exp_b10;
+
+ else if (ch == 46)
+ {
+ ch = *--ascii, ++size;
+ /* Advance exp_b10 to '1', so that the
+ * decimal point happens after the
+ * previous digit.
+ */
+ exp_b10 = 1;
+ }
+
+ --cdigits;
+ d = ch - 47; /* I.e. 1+(ch-48) */
+ }
+
+ /* Did we reach the beginning? If so adjust the
+ * exponent but take into account the leading
+ * decimal point.
+ */
+ if (d > 9) /* cdigits == 0 */
+ {
+ if (exp_b10 == (-1))
+ {
+ /* Leading decimal point (plus zeros?), if
+ * we lose the decimal point here it must
+ * be reentered below.
+ */
+ int ch = *--ascii;
+
+ if (ch == 46)
+ ++size, exp_b10 = 1;
+
+ /* Else lost a leading zero, so 'exp_b10' is
+ * still ok at (-1)
+ */
+ }
+ else
+ ++exp_b10;
+
+ /* In all cases we output a '1' */
+ d = 1;
+ }
+ }
+ }
+ fp = 0; /* Guarantees termination below. */
+ }
+
+ if (d == 0)
+ {
+ ++czero;
+ if (cdigits == 0) ++clead;
+ }
+ else
+ {
+ /* Included embedded zeros in the digit count. */
+ cdigits += czero - clead;
+ clead = 0;
+
+ while (czero > 0)
+ {
+ /* exp_b10 == (-1) means we just output the decimal
+ * place - after the DP don't adjust 'exp_b10' any
+ * more!
+ */
+ if (exp_b10 != (-1))
+ {
+ if (exp_b10 == 0) *ascii++ = 46, --size;
+ /* PLUS 1: TOTAL 4 */
+ --exp_b10;
+ }
+ *ascii++ = 48, --czero;
+ }
+
+ if (exp_b10 != (-1))
+ {
+ if (exp_b10 == 0)
+ *ascii++ = 46, --size; /* counted above */
+
+ --exp_b10;
+ }
+ *ascii++ = (char)(48 + (int)d), ++cdigits;
+ }
+ }
+ while (cdigits+czero < precision+clead && fp > DBL_MIN);
+
+ /* The total output count (max) is now 4+precision */
+
+ /* Check for an exponent, if we don't need one we are
+ * done and just need to terminate the string. At
+ * this point exp_b10==(-1) is effectively if flag - it got
+ * to '-1' because of the decrement after outputting
+ * the decimal point above (the exponent required is
+ * *not* -1!)
+ */
+ if (exp_b10 >= (-1) && exp_b10 <= 2)
+ {
+ /* The following only happens if we didn't output the
+ * leading zeros above for negative exponent, so this
+ * doesn't add to the digit requirement. Note that the
+ * two zeros here can only be output if the two leading
+ * zeros were *not* output, so this doesn't increase
+ * the output count.
+ */
+ while (--exp_b10 >= 0) *ascii++ = 48;
+
+ *ascii = 0;
+
+ /* Total buffer requirement (including the '\0') is
+ * 5+precision - see check at the start.
+ */
+ return;
+ }
+
+ /* Here if an exponent is required, adjust size for
+ * the digits we output but did not count. The total
+ * digit output here so far is at most 1+precision - no
+ * decimal point and no leading or trailing zeros have
+ * been output.
+ */
+ size -= cdigits;
+
+ *ascii++ = 69, --size; /* 'E': PLUS 1 TOTAL 2+precision */
+
+ /* The following use of an unsigned temporary avoids ambiguities in
+ * the signed arithmetic on exp_b10 and permits GCC at least to do
+ * better optimization.
+ */
+ {
+ unsigned int uexp_b10;
+
+ if (exp_b10 < 0)
+ {
+ *ascii++ = 45, --size; /* '-': PLUS 1 TOTAL 3+precision */
+ uexp_b10 = -exp_b10;
+ }
+
+ else
+ uexp_b10 = exp_b10;
+
+ cdigits = 0;
+
+ while (uexp_b10 > 0)
+ {
+ exponent[cdigits++] = (char)(48 + uexp_b10 % 10);
+ uexp_b10 /= 10;
+ }
+ }
+
+ /* Need another size check here for the exponent digits, so
+ * this need not be considered above.
+ */
+ if (size > cdigits)
+ {
+ while (cdigits > 0) *ascii++ = exponent[--cdigits];
+
+ *ascii = 0;
+
+ return;
+ }
+ }
+ }
+ else if (!(fp >= DBL_MIN))
+ {
+ *ascii++ = 48; /* '0' */
+ *ascii = 0;
+ return;
+ }
+ else
+ {
+ *ascii++ = 105; /* 'i' */
+ *ascii++ = 110; /* 'n' */
+ *ascii++ = 102; /* 'f' */
+ *ascii = 0;
+ return;
+ }
+ }
+
+ /* Here on buffer too small. */
+ png_error(png_ptr, "ASCII conversion buffer too small");
+}
+
+# endif /* FLOATING_POINT */
+
+# ifdef PNG_FIXED_POINT_SUPPORTED
+/* Function to format a fixed point value in ASCII.
+ */
+void /* PRIVATE */
+png_ascii_from_fixed(png_const_structrp png_ptr, png_charp ascii,
+ png_size_t size, png_fixed_point fp)
+{
+ /* Require space for 10 decimal digits, a decimal point, a minus sign and a
+ * trailing \0, 13 characters:
+ */
+ if (size > 12)
+ {
+ png_uint_32 num;
+
+ /* Avoid overflow here on the minimum integer. */
+ if (fp < 0)
+ *ascii++ = 45, num = -fp;
+ else
+ num = fp;
+
+ if (num <= 0x80000000) /* else overflowed */
+ {
+ unsigned int ndigits = 0, first = 16 /* flag value */;
+ char digits[10];
+
+ while (num)
+ {
+ /* Split the low digit off num: */
+ unsigned int tmp = num/10;
+ num -= tmp*10;
+ digits[ndigits++] = (char)(48 + num);
+ /* Record the first non-zero digit, note that this is a number
+ * starting at 1, it's not actually the array index.
+ */
+ if (first == 16 && num > 0)
+ first = ndigits;
+ num = tmp;
+ }
+
+ if (ndigits > 0)
+ {
+ while (ndigits > 5) *ascii++ = digits[--ndigits];
+ /* The remaining digits are fractional digits, ndigits is '5' or
+ * smaller at this point. It is certainly not zero. Check for a
+ * non-zero fractional digit:
+ */
+ if (first <= 5)
+ {
+ unsigned int i;
+ *ascii++ = 46; /* decimal point */
+ /* ndigits may be <5 for small numbers, output leading zeros
+ * then ndigits digits to first:
+ */
+ i = 5;
+ while (ndigits < i) *ascii++ = 48, --i;
+ while (ndigits >= first) *ascii++ = digits[--ndigits];
+ /* Don't output the trailing zeros! */
+ }
+ }
+ else
+ *ascii++ = 48;
+
+ /* And null terminate the string: */
+ *ascii = 0;
+ return;
+ }
+ }
+
+ /* Here on buffer too small. */
+ png_error(png_ptr, "ASCII conversion buffer too small");
+}
+# endif /* FIXED_POINT */
+#endif /* SCAL */
+
+#if defined(PNG_FLOATING_POINT_SUPPORTED) && \
+ !defined(PNG_FIXED_POINT_MACRO_SUPPORTED) && \
+ (defined(PNG_gAMA_SUPPORTED) || defined(PNG_cHRM_SUPPORTED) || \
+ defined(PNG_sCAL_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) || \
+ defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)) || \
+ (defined(PNG_sCAL_SUPPORTED) && \
+ defined(PNG_FLOATING_ARITHMETIC_SUPPORTED))
+png_fixed_point
+png_fixed(png_const_structrp png_ptr, double fp, png_const_charp text)
+{
+ double r = floor(100000 * fp + .5);
+
+ if (r > 2147483647. || r < -2147483648.)
+ png_fixed_error(png_ptr, text);
+
+# ifndef PNG_ERROR_TEXT_SUPPORTED
+ PNG_UNUSED(text)
+# endif
+
+ return (png_fixed_point)r;
+}
+#endif
+
+#if defined(PNG_GAMMA_SUPPORTED) || defined(PNG_COLORSPACE_SUPPORTED) ||\
+ defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG_READ_pHYs_SUPPORTED)
+/* muldiv functions */
+/* This API takes signed arguments and rounds the result to the nearest
+ * integer (or, for a fixed point number - the standard argument - to
+ * the nearest .00001). Overflow and divide by zero are signalled in
+ * the result, a boolean - true on success, false on overflow.
+ */
+int
+png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times,
+ png_int_32 divisor)
+{
+ /* Return a * times / divisor, rounded. */
+ if (divisor != 0)
+ {
+ if (a == 0 || times == 0)
+ {
+ *res = 0;
+ return 1;
+ }
+ else
+ {
+#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+ double r = a;
+ r *= times;
+ r /= divisor;
+ r = floor(r+.5);
+
+ /* A png_fixed_point is a 32-bit integer. */
+ if (r <= 2147483647. && r >= -2147483648.)
+ {
+ *res = (png_fixed_point)r;
+ return 1;
+ }
+#else
+ int negative = 0;
+ png_uint_32 A, T, D;
+ png_uint_32 s16, s32, s00;
+
+ if (a < 0)
+ negative = 1, A = -a;
+ else
+ A = a;
+
+ if (times < 0)
+ negative = !negative, T = -times;
+ else
+ T = times;
+
+ if (divisor < 0)
+ negative = !negative, D = -divisor;
+ else
+ D = divisor;
+
+ /* Following can't overflow because the arguments only
+ * have 31 bits each, however the result may be 32 bits.
+ */
+ s16 = (A >> 16) * (T & 0xffff) +
+ (A & 0xffff) * (T >> 16);
+ /* Can't overflow because the a*times bit is only 30
+ * bits at most.
+ */
+ s32 = (A >> 16) * (T >> 16) + (s16 >> 16);
+ s00 = (A & 0xffff) * (T & 0xffff);
+
+ s16 = (s16 & 0xffff) << 16;
+ s00 += s16;
+
+ if (s00 < s16)
+ ++s32; /* carry */
+
+ if (s32 < D) /* else overflow */
+ {
+ /* s32.s00 is now the 64-bit product, do a standard
+ * division, we know that s32 < D, so the maximum
+ * required shift is 31.
+ */
+ int bitshift = 32;
+ png_fixed_point result = 0; /* NOTE: signed */
+
+ while (--bitshift >= 0)
+ {
+ png_uint_32 d32, d00;
+
+ if (bitshift > 0)
+ d32 = D >> (32-bitshift), d00 = D << bitshift;
+
+ else
+ d32 = 0, d00 = D;
+
+ if (s32 > d32)
+ {
+ if (s00 < d00) --s32; /* carry */
+ s32 -= d32, s00 -= d00, result += 1<<bitshift;
+ }
+
+ else
+ if (s32 == d32 && s00 >= d00)
+ s32 = 0, s00 -= d00, result += 1<<bitshift;
+ }
+
+ /* Handle the rounding. */
+ if (s00 >= (D >> 1))
+ ++result;
+
+ if (negative != 0)
+ result = -result;
+
+ /* Check for overflow. */
+ if ((negative != 0 && result <= 0) ||
+ (negative == 0 && result >= 0))
+ {
+ *res = result;
+ return 1;
+ }
+ }
+#endif
+ }
+ }
+
+ return 0;
+}
+#endif /* READ_GAMMA || INCH_CONVERSIONS */
+
+#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED)
+/* The following is for when the caller doesn't much care about the
+ * result.
+ */
+png_fixed_point
+png_muldiv_warn(png_const_structrp png_ptr, png_fixed_point a, png_int_32 times,
+ png_int_32 divisor)
+{
+ png_fixed_point result;
+
+ if (png_muldiv(&result, a, times, divisor) != 0)
+ return result;
+
+ png_warning(png_ptr, "fixed point overflow ignored");
+ return 0;
+}
+#endif
+
+#ifdef PNG_GAMMA_SUPPORTED /* more fixed point functions for gamma */
+/* Calculate a reciprocal, return 0 on div-by-zero or overflow. */
+png_fixed_point
+png_reciprocal(png_fixed_point a)
+{
+#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+ double r = floor(1E10/a+.5);
+
+ if (r <= 2147483647. && r >= -2147483648.)
+ return (png_fixed_point)r;
+#else
+ png_fixed_point res;
+
+ if (png_muldiv(&res, 100000, 100000, a) != 0)
+ return res;
+#endif
+
+ return 0; /* error/overflow */
+}
+
+/* This is the shared test on whether a gamma value is 'significant' - whether
+ * it is worth doing gamma correction.
+ */
+int /* PRIVATE */
+png_gamma_significant(png_fixed_point gamma_val)
+{
+ return gamma_val < PNG_FP_1 - PNG_GAMMA_THRESHOLD_FIXED ||
+ gamma_val > PNG_FP_1 + PNG_GAMMA_THRESHOLD_FIXED;
+}
+#endif
+
+#ifdef PNG_READ_GAMMA_SUPPORTED
+#ifdef PNG_16BIT_SUPPORTED
+/* A local convenience routine. */
+static png_fixed_point
+png_product2(png_fixed_point a, png_fixed_point b)
+{
+ /* The required result is 1/a * 1/b; the following preserves accuracy. */
+#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+ double r = a * 1E-5;
+ r *= b;
+ r = floor(r+.5);
+
+ if (r <= 2147483647. && r >= -2147483648.)
+ return (png_fixed_point)r;
+#else
+ png_fixed_point res;
+
+ if (png_muldiv(&res, a, b, 100000) != 0)
+ return res;
+#endif
+
+ return 0; /* overflow */
+}
+#endif /* 16BIT */
+
+/* The inverse of the above. */
+png_fixed_point
+png_reciprocal2(png_fixed_point a, png_fixed_point b)
+{
+ /* The required result is 1/a * 1/b; the following preserves accuracy. */
+#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+ if (a != 0 && b != 0)
+ {
+ double r = 1E15/a;
+ r /= b;
+ r = floor(r+.5);
+
+ if (r <= 2147483647. && r >= -2147483648.)
+ return (png_fixed_point)r;
+ }
+#else
+ /* This may overflow because the range of png_fixed_point isn't symmetric,
+ * but this API is only used for the product of file and screen gamma so it
+ * doesn't matter that the smallest number it can produce is 1/21474, not
+ * 1/100000
+ */
+ png_fixed_point res = png_product2(a, b);
+
+ if (res != 0)
+ return png_reciprocal(res);
+#endif
+
+ return 0; /* overflow */
+}
+#endif /* READ_GAMMA */
+
+#ifdef PNG_READ_GAMMA_SUPPORTED /* gamma table code */
+#ifndef PNG_FLOATING_ARITHMETIC_SUPPORTED
+/* Fixed point gamma.
+ *
+ * The code to calculate the tables used below can be found in the shell script
+ * contrib/tools/intgamma.sh
+ *
+ * To calculate gamma this code implements fast log() and exp() calls using only
+ * fixed point arithmetic. This code has sufficient precision for either 8-bit
+ * or 16-bit sample values.
+ *
+ * The tables used here were calculated using simple 'bc' programs, but C double
+ * precision floating point arithmetic would work fine.
+ *
+ * 8-bit log table
+ * This is a table of -log(value/255)/log(2) for 'value' in the range 128 to
+ * 255, so it's the base 2 logarithm of a normalized 8-bit floating point
+ * mantissa. The numbers are 32-bit fractions.
+ */
+static const png_uint_32
+png_8bit_l2[128] =
+{
+ 4270715492U, 4222494797U, 4174646467U, 4127164793U, 4080044201U, 4033279239U,
+ 3986864580U, 3940795015U, 3895065449U, 3849670902U, 3804606499U, 3759867474U,
+ 3715449162U, 3671346997U, 3627556511U, 3584073329U, 3540893168U, 3498011834U,
+ 3455425220U, 3413129301U, 3371120137U, 3329393864U, 3287946700U, 3246774933U,
+ 3205874930U, 3165243125U, 3124876025U, 3084770202U, 3044922296U, 3005329011U,
+ 2965987113U, 2926893432U, 2888044853U, 2849438323U, 2811070844U, 2772939474U,
+ 2735041326U, 2697373562U, 2659933400U, 2622718104U, 2585724991U, 2548951424U,
+ 2512394810U, 2476052606U, 2439922311U, 2404001468U, 2368287663U, 2332778523U,
+ 2297471715U, 2262364947U, 2227455964U, 2192742551U, 2158222529U, 2123893754U,
+ 2089754119U, 2055801552U, 2022034013U, 1988449497U, 1955046031U, 1921821672U,
+ 1888774511U, 1855902668U, 1823204291U, 1790677560U, 1758320682U, 1726131893U,
+ 1694109454U, 1662251657U, 1630556815U, 1599023271U, 1567649391U, 1536433567U,
+ 1505374214U, 1474469770U, 1443718700U, 1413119487U, 1382670639U, 1352370686U,
+ 1322218179U, 1292211689U, 1262349810U, 1232631153U, 1203054352U, 1173618059U,
+ 1144320946U, 1115161701U, 1086139034U, 1057251672U, 1028498358U, 999877854U,
+ 971388940U, 943030410U, 914801076U, 886699767U, 858725327U, 830876614U,
+ 803152505U, 775551890U, 748073672U, 720716771U, 693480120U, 666362667U,
+ 639363374U, 612481215U, 585715177U, 559064263U, 532527486U, 506103872U,
+ 479792461U, 453592303U, 427502463U, 401522014U, 375650043U, 349885648U,
+ 324227938U, 298676034U, 273229066U, 247886176U, 222646516U, 197509248U,
+ 172473545U, 147538590U, 122703574U, 97967701U, 73330182U, 48790236U,
+ 24347096U, 0U
+
+#if 0
+ /* The following are the values for 16-bit tables - these work fine for the
+ * 8-bit conversions but produce very slightly larger errors in the 16-bit
+ * log (about 1.2 as opposed to 0.7 absolute error in the final value). To
+ * use these all the shifts below must be adjusted appropriately.
+ */
+ 65166, 64430, 63700, 62976, 62257, 61543, 60835, 60132, 59434, 58741, 58054,
+ 57371, 56693, 56020, 55352, 54689, 54030, 53375, 52726, 52080, 51439, 50803,
+ 50170, 49542, 48918, 48298, 47682, 47070, 46462, 45858, 45257, 44661, 44068,
+ 43479, 42894, 42312, 41733, 41159, 40587, 40020, 39455, 38894, 38336, 37782,
+ 37230, 36682, 36137, 35595, 35057, 34521, 33988, 33459, 32932, 32408, 31887,
+ 31369, 30854, 30341, 29832, 29325, 28820, 28319, 27820, 27324, 26830, 26339,
+ 25850, 25364, 24880, 24399, 23920, 23444, 22970, 22499, 22029, 21562, 21098,
+ 20636, 20175, 19718, 19262, 18808, 18357, 17908, 17461, 17016, 16573, 16132,
+ 15694, 15257, 14822, 14390, 13959, 13530, 13103, 12678, 12255, 11834, 11415,
+ 10997, 10582, 10168, 9756, 9346, 8937, 8531, 8126, 7723, 7321, 6921, 6523,
+ 6127, 5732, 5339, 4947, 4557, 4169, 3782, 3397, 3014, 2632, 2251, 1872, 1495,
+ 1119, 744, 372
+#endif
+};
+
+static png_int_32
+png_log8bit(unsigned int x)
+{
+ unsigned int lg2 = 0;
+ /* Each time 'x' is multiplied by 2, 1 must be subtracted off the final log,
+ * because the log is actually negate that means adding 1. The final
+ * returned value thus has the range 0 (for 255 input) to 7.994 (for 1
+ * input), return -1 for the overflow (log 0) case, - so the result is
+ * always at most 19 bits.
+ */
+ if ((x &= 0xff) == 0)
+ return -1;
+
+ if ((x & 0xf0) == 0)
+ lg2 = 4, x <<= 4;
+
+ if ((x & 0xc0) == 0)
+ lg2 += 2, x <<= 2;
+
+ if ((x & 0x80) == 0)
+ lg2 += 1, x <<= 1;
+
+ /* result is at most 19 bits, so this cast is safe: */
+ return (png_int_32)((lg2 << 16) + ((png_8bit_l2[x-128]+32768)>>16));
+}
+
+/* The above gives exact (to 16 binary places) log2 values for 8-bit images,
+ * for 16-bit images we use the most significant 8 bits of the 16-bit value to
+ * get an approximation then multiply the approximation by a correction factor
+ * determined by the remaining up to 8 bits. This requires an additional step
+ * in the 16-bit case.
+ *
+ * We want log2(value/65535), we have log2(v'/255), where:
+ *
+ * value = v' * 256 + v''
+ * = v' * f
+ *
+ * So f is value/v', which is equal to (256+v''/v') since v' is in the range 128
+ * to 255 and v'' is in the range 0 to 255 f will be in the range 256 to less
+ * than 258. The final factor also needs to correct for the fact that our 8-bit
+ * value is scaled by 255, whereas the 16-bit values must be scaled by 65535.
+ *
+ * This gives a final formula using a calculated value 'x' which is value/v' and
+ * scaling by 65536 to match the above table:
+ *
+ * log2(x/257) * 65536
+ *
+ * Since these numbers are so close to '1' we can use simple linear
+ * interpolation between the two end values 256/257 (result -368.61) and 258/257
+ * (result 367.179). The values used below are scaled by a further 64 to give
+ * 16-bit precision in the interpolation:
+ *
+ * Start (256): -23591
+ * Zero (257): 0
+ * End (258): 23499
+ */
+#ifdef PNG_16BIT_SUPPORTED
+static png_int_32
+png_log16bit(png_uint_32 x)
+{
+ unsigned int lg2 = 0;
+
+ /* As above, but now the input has 16 bits. */
+ if ((x &= 0xffff) == 0)
+ return -1;
+
+ if ((x & 0xff00) == 0)
+ lg2 = 8, x <<= 8;
+
+ if ((x & 0xf000) == 0)
+ lg2 += 4, x <<= 4;
+
+ if ((x & 0xc000) == 0)
+ lg2 += 2, x <<= 2;
+
+ if ((x & 0x8000) == 0)
+ lg2 += 1, x <<= 1;
+
+ /* Calculate the base logarithm from the top 8 bits as a 28-bit fractional
+ * value.
+ */
+ lg2 <<= 28;
+ lg2 += (png_8bit_l2[(x>>8)-128]+8) >> 4;
+
+ /* Now we need to interpolate the factor, this requires a division by the top
+ * 8 bits. Do this with maximum precision.
+ */
+ x = ((x << 16) + (x >> 9)) / (x >> 8);
+
+ /* Since we divided by the top 8 bits of 'x' there will be a '1' at 1<<24,
+ * the value at 1<<16 (ignoring this) will be 0 or 1; this gives us exactly
+ * 16 bits to interpolate to get the low bits of the result. Round the
+ * answer. Note that the end point values are scaled by 64 to retain overall
+ * precision and that 'lg2' is current scaled by an extra 12 bits, so adjust
+ * the overall scaling by 6-12. Round at every step.
+ */
+ x -= 1U << 24;
+
+ if (x <= 65536U) /* <= '257' */
+ lg2 += ((23591U * (65536U-x)) + (1U << (16+6-12-1))) >> (16+6-12);
+
+ else
+ lg2 -= ((23499U * (x-65536U)) + (1U << (16+6-12-1))) >> (16+6-12);
+
+ /* Safe, because the result can't have more than 20 bits: */
+ return (png_int_32)((lg2 + 2048) >> 12);
+}
+#endif /* 16BIT */
+
+/* The 'exp()' case must invert the above, taking a 20-bit fixed point
+ * logarithmic value and returning a 16 or 8-bit number as appropriate. In
+ * each case only the low 16 bits are relevant - the fraction - since the
+ * integer bits (the top 4) simply determine a shift.
+ *
+ * The worst case is the 16-bit distinction between 65535 and 65534. This
+ * requires perhaps spurious accuracy in the decoding of the logarithm to
+ * distinguish log2(65535/65534.5) - 10^-5 or 17 bits. There is little chance
+ * of getting this accuracy in practice.
+ *
+ * To deal with this the following exp() function works out the exponent of the
+ * frational part of the logarithm by using an accurate 32-bit value from the
+ * top four fractional bits then multiplying in the remaining bits.
+ */
+static const png_uint_32
+png_32bit_exp[16] =
+{
+ /* NOTE: the first entry is deliberately set to the maximum 32-bit value. */
+ 4294967295U, 4112874773U, 3938502376U, 3771522796U, 3611622603U, 3458501653U,
+ 3311872529U, 3171459999U, 3037000500U, 2908241642U, 2784941738U, 2666869345U,
+ 2553802834U, 2445529972U, 2341847524U, 2242560872U
+};
+
+/* Adjustment table; provided to explain the numbers in the code below. */
+#if 0
+for (i=11;i>=0;--i){ print i, " ", (1 - e(-(2^i)/65536*l(2))) * 2^(32-i), "\n"}
+ 11 44937.64284865548751208448
+ 10 45180.98734845585101160448
+ 9 45303.31936980687359311872
+ 8 45364.65110595323018870784
+ 7 45395.35850361789624614912
+ 6 45410.72259715102037508096
+ 5 45418.40724413220722311168
+ 4 45422.25021786898173001728
+ 3 45424.17186732298419044352
+ 2 45425.13273269940811464704
+ 1 45425.61317555035558641664
+ 0 45425.85339951654943850496
+#endif
+
+static png_uint_32
+png_exp(png_fixed_point x)
+{
+ if (x > 0 && x <= 0xfffff) /* Else overflow or zero (underflow) */
+ {
+ /* Obtain a 4-bit approximation */
+ png_uint_32 e = png_32bit_exp[(x >> 12) & 0x0f];
+
+ /* Incorporate the low 12 bits - these decrease the returned value by
+ * multiplying by a number less than 1 if the bit is set. The multiplier
+ * is determined by the above table and the shift. Notice that the values
+ * converge on 45426 and this is used to allow linear interpolation of the
+ * low bits.
+ */
+ if (x & 0x800)
+ e -= (((e >> 16) * 44938U) + 16U) >> 5;
+
+ if (x & 0x400)
+ e -= (((e >> 16) * 45181U) + 32U) >> 6;
+
+ if (x & 0x200)
+ e -= (((e >> 16) * 45303U) + 64U) >> 7;
+
+ if (x & 0x100)
+ e -= (((e >> 16) * 45365U) + 128U) >> 8;
+
+ if (x & 0x080)
+ e -= (((e >> 16) * 45395U) + 256U) >> 9;
+
+ if (x & 0x040)
+ e -= (((e >> 16) * 45410U) + 512U) >> 10;
+
+ /* And handle the low 6 bits in a single block. */
+ e -= (((e >> 16) * 355U * (x & 0x3fU)) + 256U) >> 9;
+
+ /* Handle the upper bits of x. */
+ e >>= x >> 16;
+ return e;
+ }
+
+ /* Check for overflow */
+ if (x <= 0)
+ return png_32bit_exp[0];
+
+ /* Else underflow */
+ return 0;
+}
+
+static png_byte
+png_exp8bit(png_fixed_point lg2)
+{
+ /* Get a 32-bit value: */
+ png_uint_32 x = png_exp(lg2);
+
+ /* Convert the 32-bit value to 0..255 by multiplying by 256-1. Note that the
+ * second, rounding, step can't overflow because of the first, subtraction,
+ * step.
+ */
+ x -= x >> 8;
+ return (png_byte)(((x + 0x7fffffU) >> 24) & 0xff);
+}
+
+#ifdef PNG_16BIT_SUPPORTED
+static png_uint_16
+png_exp16bit(png_fixed_point lg2)
+{
+ /* Get a 32-bit value: */
+ png_uint_32 x = png_exp(lg2);
+
+ /* Convert the 32-bit value to 0..65535 by multiplying by 65536-1: */
+ x -= x >> 16;
+ return (png_uint_16)((x + 32767U) >> 16);
+}
+#endif /* 16BIT */
+#endif /* FLOATING_ARITHMETIC */
+
+png_byte
+png_gamma_8bit_correct(unsigned int value, png_fixed_point gamma_val)
+{
+ if (value > 0 && value < 255)
+ {
+# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+ /* 'value' is unsigned, ANSI-C90 requires the compiler to correctly
+ * convert this to a floating point value. This includes values that
+ * would overflow if 'value' were to be converted to 'int'.
+ *
+ * Apparently GCC, however, does an intermediate conversion to (int)
+ * on some (ARM) but not all (x86) platforms, possibly because of
+ * hardware FP limitations. (E.g. if the hardware conversion always
+ * assumes the integer register contains a signed value.) This results
+ * in ANSI-C undefined behavior for large values.
+ *
+ * Other implementations on the same machine might actually be ANSI-C90
+ * conformant and therefore compile spurious extra code for the large
+ * values.
+ *
+ * We can be reasonably sure that an unsigned to float conversion
+ * won't be faster than an int to float one. Therefore this code
+ * assumes responsibility for the undefined behavior, which it knows
+ * can't happen because of the check above.
+ *
+ * Note the argument to this routine is an (unsigned int) because, on
+ * 16-bit platforms, it is assigned a value which might be out of
+ * range for an (int); that would result in undefined behavior in the
+ * caller if the *argument* ('value') were to be declared (int).
+ */
+ double r = floor(255*pow((int)/*SAFE*/value/255.,gamma_val*.00001)+.5);
+ return (png_byte)r;
+# else
+ png_int_32 lg2 = png_log8bit(value);
+ png_fixed_point res;
+
+ if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0)
+ return png_exp8bit(res);
+
+ /* Overflow. */
+ value = 0;
+# endif
+ }
+
+ return (png_byte)(value & 0xff);
+}
+
+#ifdef PNG_16BIT_SUPPORTED
+png_uint_16
+png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val)
+{
+ if (value > 0 && value < 65535)
+ {
+# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+ /* The same (unsigned int)->(double) constraints apply here as above,
+ * however in this case the (unsigned int) to (int) conversion can
+ * overflow on an ANSI-C90 compliant system so the cast needs to ensure
+ * that this is not possible.
+ */
+ double r = floor(65535*pow((png_int_32)value/65535.,
+ gamma_val*.00001)+.5);
+ return (png_uint_16)r;
+# else
+ png_int_32 lg2 = png_log16bit(value);
+ png_fixed_point res;
+
+ if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0)
+ return png_exp16bit(res);
+
+ /* Overflow. */
+ value = 0;
+# endif
+ }
+
+ return (png_uint_16)value;
+}
+#endif /* 16BIT */
+
+/* This does the right thing based on the bit_depth field of the
+ * png_struct, interpreting values as 8-bit or 16-bit. While the result
+ * is nominally a 16-bit value if bit depth is 8 then the result is
+ * 8-bit (as are the arguments.)
+ */
+png_uint_16 /* PRIVATE */
+png_gamma_correct(png_structrp png_ptr, unsigned int value,
+ png_fixed_point gamma_val)
+{
+ if (png_ptr->bit_depth == 8)
+ return png_gamma_8bit_correct(value, gamma_val);
+
+#ifdef PNG_16BIT_SUPPORTED
+ else
+ return png_gamma_16bit_correct(value, gamma_val);
+#else
+ /* should not reach this */
+ return 0;
+#endif /* 16BIT */
+}
+
+#ifdef PNG_16BIT_SUPPORTED
+/* Internal function to build a single 16-bit table - the table consists of
+ * 'num' 256 entry subtables, where 'num' is determined by 'shift' - the amount
+ * to shift the input values right (or 16-number_of_signifiant_bits).
+ *
+ * The caller is responsible for ensuring that the table gets cleaned up on
+ * png_error (i.e. if one of the mallocs below fails) - i.e. the *table argument
+ * should be somewhere that will be cleaned.
+ */
+static void
+png_build_16bit_table(png_structrp png_ptr, png_uint_16pp *ptable,
+ PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
+{
+ /* Various values derived from 'shift': */
+ PNG_CONST unsigned int num = 1U << (8U - shift);
+#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+ /* CSE the division and work round wacky GCC warnings (see the comments
+ * in png_gamma_8bit_correct for where these come from.)
+ */
+ PNG_CONST double fmax = 1./(((png_int_32)1 << (16U - shift))-1);
+#endif
+ PNG_CONST unsigned int max = (1U << (16U - shift))-1U;
+ PNG_CONST unsigned int max_by_2 = 1U << (15U-shift);
+ unsigned int i;
+
+ png_uint_16pp table = *ptable =
+ (png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p)));
+
+ for (i = 0; i < num; i++)
+ {
+ png_uint_16p sub_table = table[i] =
+ (png_uint_16p)png_malloc(png_ptr, 256 * (sizeof (png_uint_16)));
+
+ /* The 'threshold' test is repeated here because it can arise for one of
+ * the 16-bit tables even if the others don't hit it.
+ */
+ if (png_gamma_significant(gamma_val) != 0)
+ {
+ /* The old code would overflow at the end and this would cause the
+ * 'pow' function to return a result >1, resulting in an
+ * arithmetic error. This code follows the spec exactly; ig is
+ * the recovered input sample, it always has 8-16 bits.
+ *
+ * We want input * 65535/max, rounded, the arithmetic fits in 32
+ * bits (unsigned) so long as max <= 32767.
+ */
+ unsigned int j;
+ for (j = 0; j < 256; j++)
+ {
+ png_uint_32 ig = (j << (8-shift)) + i;
+# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
+ /* Inline the 'max' scaling operation: */
+ /* See png_gamma_8bit_correct for why the cast to (int) is
+ * required here.
+ */
+ double d = floor(65535.*pow(ig*fmax, gamma_val*.00001)+.5);
+ sub_table[j] = (png_uint_16)d;
+# else
+ if (shift != 0)
+ ig = (ig * 65535U + max_by_2)/max;
+
+ sub_table[j] = png_gamma_16bit_correct(ig, gamma_val);
+# endif
+ }
+ }
+ else
+ {
+ /* We must still build a table, but do it the fast way. */
+ unsigned int j;
+
+ for (j = 0; j < 256; j++)
+ {
+ png_uint_32 ig = (j << (8-shift)) + i;
+
+ if (shift != 0)
+ ig = (ig * 65535U + max_by_2)/max;
+
+ sub_table[j] = (png_uint_16)ig;
+ }
+ }
+ }
+}
+
+/* NOTE: this function expects the *inverse* of the overall gamma transformation
+ * required.
+ */
+static void
+png_build_16to8_table(png_structrp png_ptr, png_uint_16pp *ptable,
+ PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
+{
+ PNG_CONST unsigned int num = 1U << (8U - shift);
+ PNG_CONST unsigned int max = (1U << (16U - shift))-1U;
+ unsigned int i;
+ png_uint_32 last;
+
+ png_uint_16pp table = *ptable =
+ (png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p)));
+
+ /* 'num' is the number of tables and also the number of low bits of low
+ * bits of the input 16-bit value used to select a table. Each table is
+ * itself indexed by the high 8 bits of the value.
+ */
+ for (i = 0; i < num; i++)
+ table[i] = (png_uint_16p)png_malloc(png_ptr,
+ 256 * (sizeof (png_uint_16)));
+
+ /* 'gamma_val' is set to the reciprocal of the value calculated above, so
+ * pow(out,g) is an *input* value. 'last' is the last input value set.
+ *
+ * In the loop 'i' is used to find output values. Since the output is
+ * 8-bit there are only 256 possible values. The tables are set up to
+ * select the closest possible output value for each input by finding
+ * the input value at the boundary between each pair of output values
+ * and filling the table up to that boundary with the lower output
+ * value.
+ *
+ * The boundary values are 0.5,1.5..253.5,254.5. Since these are 9-bit
+ * values the code below uses a 16-bit value in i; the values start at
+ * 128.5 (for 0.5) and step by 257, for a total of 254 values (the last
+ * entries are filled with 255). Start i at 128 and fill all 'last'
+ * table entries <= 'max'
+ */
+ last = 0;
+ for (i = 0; i < 255; ++i) /* 8-bit output value */
+ {
+ /* Find the corresponding maximum input value */
+ png_uint_16 out = (png_uint_16)(i * 257U); /* 16-bit output value */
+
+ /* Find the boundary value in 16 bits: */
+ png_uint_32 bound = png_gamma_16bit_correct(out+128U, gamma_val);
+
+ /* Adjust (round) to (16-shift) bits: */
+ bound = (bound * max + 32768U)/65535U + 1U;
+
+ while (last < bound)
+ {
+ table[last & (0xffU >> shift)][last >> (8U - shift)] = out;
+ last++;
+ }
+ }
+
+ /* And fill in the final entries. */
+ while (last < (num << 8))
+ {
+ table[last & (0xff >> shift)][last >> (8U - shift)] = 65535U;
+ last++;
+ }
+}
+#endif /* 16BIT */
+
+/* Build a single 8-bit table: same as the 16-bit case but much simpler (and
+ * typically much faster). Note that libpng currently does no sBIT processing
+ * (apparently contrary to the spec) so a 256-entry table is always generated.
+ */
+static void
+png_build_8bit_table(png_structrp png_ptr, png_bytepp ptable,
+ PNG_CONST png_fixed_point gamma_val)
+{
+ unsigned int i;
+ png_bytep table = *ptable = (png_bytep)png_malloc(png_ptr, 256);
+
+ if (png_gamma_significant(gamma_val) != 0)
+ for (i=0; i<256; i++)
+ table[i] = png_gamma_8bit_correct(i, gamma_val);
+
+ else
+ for (i=0; i<256; ++i)
+ table[i] = (png_byte)(i & 0xff);
+}
+
+/* Used from png_read_destroy and below to release the memory used by the gamma
+ * tables.
+ */
+void /* PRIVATE */
+png_destroy_gamma_table(png_structrp png_ptr)
+{
+ png_free(png_ptr, png_ptr->gamma_table);
+ png_ptr->gamma_table = NULL;
+
+#ifdef PNG_16BIT_SUPPORTED
+ if (png_ptr->gamma_16_table != NULL)
+ {
+ int i;
+ int istop = (1 << (8 - png_ptr->gamma_shift));
+ for (i = 0; i < istop; i++)
+ {
+ png_free(png_ptr, png_ptr->gamma_16_table[i]);
+ }
+ png_free(png_ptr, png_ptr->gamma_16_table);
+ png_ptr->gamma_16_table = NULL;
+ }
+#endif /* 16BIT */
+
+#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
+ defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
+ defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
+ png_free(png_ptr, png_ptr->gamma_from_1);
+ png_ptr->gamma_from_1 = NULL;
+ png_free(png_ptr, png_ptr->gamma_to_1);
+ png_ptr->gamma_to_1 = NULL;
+
+#ifdef PNG_16BIT_SUPPORTED
+ if (png_ptr->gamma_16_from_1 != NULL)
+ {
+ int i;
+ int istop = (1 << (8 - png_ptr->gamma_shift));
+ for (i = 0; i < istop; i++)
+ {
+ png_free(png_ptr, png_ptr->gamma_16_from_1[i]);
+ }
+ png_free(png_ptr, png_ptr->gamma_16_from_1);
+ png_ptr->gamma_16_from_1 = NULL;
+ }
+ if (png_ptr->gamma_16_to_1 != NULL)
+ {
+ int i;
+ int istop = (1 << (8 - png_ptr->gamma_shift));
+ for (i = 0; i < istop; i++)
+ {
+ png_free(png_ptr, png_ptr->gamma_16_to_1[i]);
+ }
+ png_free(png_ptr, png_ptr->gamma_16_to_1);
+ png_ptr->gamma_16_to_1 = NULL;
+ }
+#endif /* 16BIT */
+#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
+}
+
+/* We build the 8- or 16-bit gamma tables here. Note that for 16-bit
+ * tables, we don't make a full table if we are reducing to 8-bit in
+ * the future. Note also how the gamma_16 tables are segmented so that
+ * we don't need to allocate > 64K chunks for a full 16-bit table.
+ */
+void /* PRIVATE */
+png_build_gamma_table(png_structrp png_ptr, int bit_depth)
+{
+ png_debug(1, "in png_build_gamma_table");
+
+ /* Remove any existing table; this copes with multiple calls to
+ * png_read_update_info. The warning is because building the gamma tables
+ * multiple times is a performance hit - it's harmless but the ability to call
+ * png_read_update_info() multiple times is new in 1.5.6 so it seems sensible
+ * to warn if the app introduces such a hit.
+ */
+ if (png_ptr->gamma_table != NULL || png_ptr->gamma_16_table != NULL)
+ {
+ png_warning(png_ptr, "gamma table being rebuilt");
+ png_destroy_gamma_table(png_ptr);
+ }
+
+ if (bit_depth <= 8)
+ {
+ png_build_8bit_table(png_ptr, &png_ptr->gamma_table,
+ png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma,
+ png_ptr->screen_gamma) : PNG_FP_1);
+
+#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
+ defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
+ defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
+ if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
+ {
+ png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1,
+ png_reciprocal(png_ptr->colorspace.gamma));
+
+ png_build_8bit_table(png_ptr, &png_ptr->gamma_from_1,
+ png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
+ png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
+ }
+#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
+ }
+#ifdef PNG_16BIT_SUPPORTED
+ else
+ {
+ png_byte shift, sig_bit;
+
+ if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
+ {
+ sig_bit = png_ptr->sig_bit.red;
+
+ if (png_ptr->sig_bit.green > sig_bit)
+ sig_bit = png_ptr->sig_bit.green;
+
+ if (png_ptr->sig_bit.blue > sig_bit)
+ sig_bit = png_ptr->sig_bit.blue;
+ }
+ else
+ sig_bit = png_ptr->sig_bit.gray;
+
+ /* 16-bit gamma code uses this equation:
+ *
+ * ov = table[(iv & 0xff) >> gamma_shift][iv >> 8]
+ *
+ * Where 'iv' is the input color value and 'ov' is the output value -
+ * pow(iv, gamma).
+ *
+ * Thus the gamma table consists of up to 256 256-entry tables. The table
+ * is selected by the (8-gamma_shift) most significant of the low 8 bits of
+ * the color value then indexed by the upper 8 bits:
+ *
+ * table[low bits][high 8 bits]
+ *
+ * So the table 'n' corresponds to all those 'iv' of:
+ *
+ * <all high 8-bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1>
+ *
+ */
+ if (sig_bit > 0 && sig_bit < 16U)
+ /* shift == insignificant bits */
+ shift = (png_byte)((16U - sig_bit) & 0xff);
+
+ else
+ shift = 0; /* keep all 16 bits */
+
+ if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
+ {
+ /* PNG_MAX_GAMMA_8 is the number of bits to keep - effectively
+ * the significant bits in the *input* when the output will
+ * eventually be 8 bits. By default it is 11.
+ */
+ if (shift < (16U - PNG_MAX_GAMMA_8))
+ shift = (16U - PNG_MAX_GAMMA_8);
+ }
+
+ if (shift > 8U)
+ shift = 8U; /* Guarantees at least one table! */
+
+ png_ptr->gamma_shift = shift;
+
+ /* NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now
+ * PNG_COMPOSE). This effectively smashed the background calculation for
+ * 16-bit output because the 8-bit table assumes the result will be reduced
+ * to 8 bits.
+ */
+ if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
+ png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift,
+ png_ptr->screen_gamma > 0 ? png_product2(png_ptr->colorspace.gamma,
+ png_ptr->screen_gamma) : PNG_FP_1);
+
+ else
+ png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift,
+ png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma,
+ png_ptr->screen_gamma) : PNG_FP_1);
+
+#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
+ defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
+ defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
+ if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
+ {
+ png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift,
+ png_reciprocal(png_ptr->colorspace.gamma));
+
+ /* Notice that the '16 from 1' table should be full precision, however
+ * the lookup on this table still uses gamma_shift, so it can't be.
+ * TODO: fix this.
+ */
+ png_build_16bit_table(png_ptr, &png_ptr->gamma_16_from_1, shift,
+ png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
+ png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
+ }
+#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
+ }
+#endif /* 16BIT */
+}
+#endif /* READ_GAMMA */
+
+/* HARDWARE OR SOFTWARE OPTION SUPPORT */
+#ifdef PNG_SET_OPTION_SUPPORTED
+int PNGAPI
+png_set_option(png_structrp png_ptr, int option, int onoff)
+{
+ if (png_ptr != NULL && option >= 0 && option < PNG_OPTION_NEXT &&
+ (option & 1) == 0)
+ {
+ int mask = 3 << option;
+ int setting = (2 + (onoff != 0)) << option;
+ int current = png_ptr->options;
+
+ png_ptr->options = (png_byte)(((current & ~mask) | setting) & 0xff);
+
+ return (current & mask) >> option;
+ }
+
+ return PNG_OPTION_INVALID;
+}
+#endif
+
+/* sRGB support */
+#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
+ defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
+/* sRGB conversion tables; these are machine generated with the code in
+ * contrib/tools/makesRGB.c. The actual sRGB transfer curve defined in the
+ * specification (see the article at http://en.wikipedia.org/wiki/SRGB)
+ * is used, not the gamma=1/2.2 approximation use elsewhere in libpng.
+ * The sRGB to linear table is exact (to the nearest 16-bit linear fraction).
+ * The inverse (linear to sRGB) table has accuracies as follows:
+ *
+ * For all possible (255*65535+1) input values:
+ *
+ * error: -0.515566 - 0.625971, 79441 (0.475369%) of readings inexact
+ *
+ * For the input values corresponding to the 65536 16-bit values:
+ *
+ * error: -0.513727 - 0.607759, 308 (0.469978%) of readings inexact
+ *
+ * In all cases the inexact readings are only off by one.
+ */
+
+#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
+/* The convert-to-sRGB table is only currently required for read. */
+const png_uint_16 png_sRGB_table[256] =
+{
+ 0,20,40,60,80,99,119,139,
+ 159,179,199,219,241,264,288,313,
+ 340,367,396,427,458,491,526,562,
+ 599,637,677,718,761,805,851,898,
+ 947,997,1048,1101,1156,1212,1270,1330,
+ 1391,1453,1517,1583,1651,1720,1790,1863,
+ 1937,2013,2090,2170,2250,2333,2418,2504,
+ 2592,2681,2773,2866,2961,3058,3157,3258,
+ 3360,3464,3570,3678,3788,3900,4014,4129,
+ 4247,4366,4488,4611,4736,4864,4993,5124,
+ 5257,5392,5530,5669,5810,5953,6099,6246,
+ 6395,6547,6700,6856,7014,7174,7335,7500,
+ 7666,7834,8004,8177,8352,8528,8708,8889,
+ 9072,9258,9445,9635,9828,10022,10219,10417,
+ 10619,10822,11028,11235,11446,11658,11873,12090,
+ 12309,12530,12754,12980,13209,13440,13673,13909,
+ 14146,14387,14629,14874,15122,15371,15623,15878,
+ 16135,16394,16656,16920,17187,17456,17727,18001,
+ 18277,18556,18837,19121,19407,19696,19987,20281,
+ 20577,20876,21177,21481,21787,22096,22407,22721,
+ 23038,23357,23678,24002,24329,24658,24990,25325,
+ 25662,26001,26344,26688,27036,27386,27739,28094,
+ 28452,28813,29176,29542,29911,30282,30656,31033,
+ 31412,31794,32179,32567,32957,33350,33745,34143,
+ 34544,34948,35355,35764,36176,36591,37008,37429,
+ 37852,38278,38706,39138,39572,40009,40449,40891,
+ 41337,41785,42236,42690,43147,43606,44069,44534,
+ 45002,45473,45947,46423,46903,47385,47871,48359,
+ 48850,49344,49841,50341,50844,51349,51858,52369,
+ 52884,53401,53921,54445,54971,55500,56032,56567,
+ 57105,57646,58190,58737,59287,59840,60396,60955,
+ 61517,62082,62650,63221,63795,64372,64952,65535
+};
+#endif /* SIMPLIFIED_READ */
+
+/* The base/delta tables are required for both read and write (but currently
+ * only the simplified versions.)
+ */
+const png_uint_16 png_sRGB_base[512] =
+{
+ 128,1782,3383,4644,5675,6564,7357,8074,
+ 8732,9346,9921,10463,10977,11466,11935,12384,
+ 12816,13233,13634,14024,14402,14769,15125,15473,
+ 15812,16142,16466,16781,17090,17393,17690,17981,
+ 18266,18546,18822,19093,19359,19621,19879,20133,
+ 20383,20630,20873,21113,21349,21583,21813,22041,
+ 22265,22487,22707,22923,23138,23350,23559,23767,
+ 23972,24175,24376,24575,24772,24967,25160,25352,
+ 25542,25730,25916,26101,26284,26465,26645,26823,
+ 27000,27176,27350,27523,27695,27865,28034,28201,
+ 28368,28533,28697,28860,29021,29182,29341,29500,
+ 29657,29813,29969,30123,30276,30429,30580,30730,
+ 30880,31028,31176,31323,31469,31614,31758,31902,
+ 32045,32186,32327,32468,32607,32746,32884,33021,
+ 33158,33294,33429,33564,33697,33831,33963,34095,
+ 34226,34357,34486,34616,34744,34873,35000,35127,
+ 35253,35379,35504,35629,35753,35876,35999,36122,
+ 36244,36365,36486,36606,36726,36845,36964,37083,
+ 37201,37318,37435,37551,37668,37783,37898,38013,
+ 38127,38241,38354,38467,38580,38692,38803,38915,
+ 39026,39136,39246,39356,39465,39574,39682,39790,
+ 39898,40005,40112,40219,40325,40431,40537,40642,
+ 40747,40851,40955,41059,41163,41266,41369,41471,
+ 41573,41675,41777,41878,41979,42079,42179,42279,
+ 42379,42478,42577,42676,42775,42873,42971,43068,
+ 43165,43262,43359,43456,43552,43648,43743,43839,
+ 43934,44028,44123,44217,44311,44405,44499,44592,
+ 44685,44778,44870,44962,45054,45146,45238,45329,
+ 45420,45511,45601,45692,45782,45872,45961,46051,
+ 46140,46229,46318,46406,46494,46583,46670,46758,
+ 46846,46933,47020,47107,47193,47280,47366,47452,
+ 47538,47623,47709,47794,47879,47964,48048,48133,
+ 48217,48301,48385,48468,48552,48635,48718,48801,
+ 48884,48966,49048,49131,49213,49294,49376,49458,
+ 49539,49620,49701,49782,49862,49943,50023,50103,
+ 50183,50263,50342,50422,50501,50580,50659,50738,
+ 50816,50895,50973,51051,51129,51207,51285,51362,
+ 51439,51517,51594,51671,51747,51824,51900,51977,
+ 52053,52129,52205,52280,52356,52432,52507,52582,
+ 52657,52732,52807,52881,52956,53030,53104,53178,
+ 53252,53326,53400,53473,53546,53620,53693,53766,
+ 53839,53911,53984,54056,54129,54201,54273,54345,
+ 54417,54489,54560,54632,54703,54774,54845,54916,
+ 54987,55058,55129,55199,55269,55340,55410,55480,
+ 55550,55620,55689,55759,55828,55898,55967,56036,
+ 56105,56174,56243,56311,56380,56448,56517,56585,
+ 56653,56721,56789,56857,56924,56992,57059,57127,
+ 57194,57261,57328,57395,57462,57529,57595,57662,
+ 57728,57795,57861,57927,57993,58059,58125,58191,
+ 58256,58322,58387,58453,58518,58583,58648,58713,
+ 58778,58843,58908,58972,59037,59101,59165,59230,
+ 59294,59358,59422,59486,59549,59613,59677,59740,
+ 59804,59867,59930,59993,60056,60119,60182,60245,
+ 60308,60370,60433,60495,60558,60620,60682,60744,
+ 60806,60868,60930,60992,61054,61115,61177,61238,
+ 61300,61361,61422,61483,61544,61605,61666,61727,
+ 61788,61848,61909,61969,62030,62090,62150,62211,
+ 62271,62331,62391,62450,62510,62570,62630,62689,
+ 62749,62808,62867,62927,62986,63045,63104,63163,
+ 63222,63281,63340,63398,63457,63515,63574,63632,
+ 63691,63749,63807,63865,63923,63981,64039,64097,
+ 64155,64212,64270,64328,64385,64443,64500,64557,
+ 64614,64672,64729,64786,64843,64900,64956,65013,
+ 65070,65126,65183,65239,65296,65352,65409,65465
+};
+
+const png_byte png_sRGB_delta[512] =
+{
+ 207,201,158,129,113,100,90,82,77,72,68,64,61,59,56,54,
+ 52,50,49,47,46,45,43,42,41,40,39,39,38,37,36,36,
+ 35,34,34,33,33,32,32,31,31,30,30,30,29,29,28,28,
+ 28,27,27,27,27,26,26,26,25,25,25,25,24,24,24,24,
+ 23,23,23,23,23,22,22,22,22,22,22,21,21,21,21,21,
+ 21,20,20,20,20,20,20,20,20,19,19,19,19,19,19,19,
+ 19,18,18,18,18,18,18,18,18,18,18,17,17,17,17,17,
+ 17,17,17,17,17,17,16,16,16,16,16,16,16,16,16,16,
+ 16,16,16,16,15,15,15,15,15,15,15,15,15,15,15,15,
+ 15,15,15,15,14,14,14,14,14,14,14,14,14,14,14,14,
+ 14,14,14,14,14,14,14,13,13,13,13,13,13,13,13,13,
+ 13,13,13,13,13,13,13,13,13,13,13,13,13,13,12,12,
+ 12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,12,
+ 12,12,12,12,12,12,12,12,12,12,12,12,11,11,11,11,
+ 11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
+ 11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,11,
+ 11,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
+ 10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
+ 10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,
+ 10,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
+ 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
+ 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
+ 9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
+ 9,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
+ 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
+ 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
+ 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
+ 8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
+ 8,8,8,8,8,8,8,8,8,7,7,7,7,7,7,7,
+ 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+ 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+ 7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
+};
+#endif /* SIMPLIFIED READ/WRITE sRGB support */
+
+/* SIMPLIFIED READ/WRITE SUPPORT */
+#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
+ defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
+static int
+png_image_free_function(png_voidp argument)
+{
+ png_imagep image = png_voidcast(png_imagep, argument);
+ png_controlp cp = image->opaque;
+ png_control c;
+
+ /* Double check that we have a png_ptr - it should be impossible to get here
+ * without one.
+ */
+ if (cp->png_ptr == NULL)
+ return 0;
+
+ /* First free any data held in the control structure. */
+# ifdef PNG_STDIO_SUPPORTED
+ if (cp->owned_file != 0)
+ {
+ FILE *fp = png_voidcast(FILE*, cp->png_ptr->io_ptr);
+ cp->owned_file = 0;
+
+ /* Ignore errors here. */
+ if (fp != NULL)
+ {
+ cp->png_ptr->io_ptr = NULL;
+ (void)fclose(fp);
+ }
+ }
+# endif
+
+ /* Copy the control structure so that the original, allocated, version can be
+ * safely freed. Notice that a png_error here stops the remainder of the
+ * cleanup, but this is probably fine because that would indicate bad memory
+ * problems anyway.
+ */
+ c = *cp;
+ image->opaque = &c;
+ png_free(c.png_ptr, cp);
+
+ /* Then the structures, calling the correct API. */
+ if (c.for_write != 0)
+ {
+# ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
+ png_destroy_write_struct(&c.png_ptr, &c.info_ptr);
+# else
+ png_error(c.png_ptr, "simplified write not supported");
+# endif
+ }
+ else
+ {
+# ifdef PNG_SIMPLIFIED_READ_SUPPORTED
+ png_destroy_read_struct(&c.png_ptr, &c.info_ptr, NULL);
+# else
+ png_error(c.png_ptr, "simplified read not supported");
+# endif
+ }
+
+ /* Success. */
+ return 1;
+}
+
+void PNGAPI
+png_image_free(png_imagep image)
+{
+ /* Safely call the real function, but only if doing so is safe at this point
+ * (if not inside an error handling context). Otherwise assume
+ * png_safe_execute will call this API after the return.
+ */
+ if (image != NULL && image->opaque != NULL &&
+ image->opaque->error_buf == NULL)
+ {
+ /* Ignore errors here: */
+ (void)png_safe_execute(image, png_image_free_function, image);
+ image->opaque = NULL;
+ }
+}
+
+int /* PRIVATE */
+png_image_error(png_imagep image, png_const_charp error_message)
+{
+ /* Utility to log an error. */
+ png_safecat(image->message, (sizeof image->message), 0, error_message);
+ image->warning_or_error |= PNG_IMAGE_ERROR;
+ png_image_free(image);
+ return 0;
+}
+
+#endif /* SIMPLIFIED READ/WRITE */
+#endif /* READ || WRITE */
diff --git a/libpng/png.h b/libpng/png.h
new file mode 100644
index 0000000..3ac3ee9
--- /dev/null
+++ b/libpng/png.h
@@ -0,0 +1,3148 @@
+
+/* png.h - header file for PNG reference library
+ *
+ * libpng version 1.6.20, December 3, 2015
+ *
+ * Copyright (c) 1998-2015 Glenn Randers-Pehrson
+ * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ *
+ * This code is released under the libpng license (See LICENSE, below)
+ *
+ * Authors and maintainers:
+ * libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
+ * libpng versions 0.89, June 1996, through 0.96, May 1997: Andreas Dilger
+ * libpng versions 0.97, January 1998, through 1.6.20, December 3, 2015:
+ * Glenn Randers-Pehrson.
+ * See also "Contributing Authors", below.
+ */
+
+/*
+ * COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
+ *
+ * If you modify libpng you may insert additional notices immediately following
+ * this sentence.
+ *
+ * This code is released under the libpng license.
+ *
+ * libpng versions 1.0.7, July 1, 2000, through 1.6.20, December 3, 2015, are
+ * Copyright (c) 2000-2002, 2004, 2006-2015 Glenn Randers-Pehrson, are
+ * derived from libpng-1.0.6, and are distributed according to the same
+ * disclaimer and license as libpng-1.0.6 with the following individuals
+ * added to the list of Contributing Authors:
+ *
+ * Simon-Pierre Cadieux
+ * Eric S. Raymond
+ * Mans Rullgard
+ * Cosmin Truta
+ * Gilles Vollant
+ * James Yu
+ *
+ * and with the following additions to the disclaimer:
+ *
+ * There is no warranty against interference with your enjoyment of the
+ * library or against infringement. There is no warranty that our
+ * efforts or the library will fulfill any of your particular purposes
+ * or needs. This library is provided with all faults, and the entire
+ * risk of satisfactory quality, performance, accuracy, and effort is with
+ * the user.
+ *
+ * libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
+ * Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from
+ * libpng-0.96, and are distributed according to the same disclaimer and
+ * license as libpng-0.96, with the following individuals added to the list
+ * of Contributing Authors:
+ *
+ * Tom Lane
+ * Glenn Randers-Pehrson
+ * Willem van Schaik
+ *
+ * libpng versions 0.89, June 1996, through 0.96, May 1997, are
+ * Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,
+ * and are distributed according to the same disclaimer and license as
+ * libpng-0.88, with the following individuals added to the list of
+ * Contributing Authors:
+ *
+ * John Bowler
+ * Kevin Bracey
+ * Sam Bushell
+ * Magnus Holmgren
+ * Greg Roelofs
+ * Tom Tanner
+ *
+ * libpng versions 0.5, May 1995, through 0.88, January 1996, are
+ * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
+ *
+ * For the purposes of this copyright and license, "Contributing Authors"
+ * is defined as the following set of individuals:
+ *
+ * Andreas Dilger
+ * Dave Martindale
+ * Guy Eric Schalnat
+ * Paul Schmidt
+ * Tim Wegner
+ *
+ * The PNG Reference Library is supplied "AS IS". The Contributing Authors
+ * and Group 42, Inc. disclaim all warranties, expressed or implied,
+ * including, without limitation, the warranties of merchantability and of
+ * fitness for any purpose. The Contributing Authors and Group 42, Inc.
+ * assume no liability for direct, indirect, incidental, special, exemplary,
+ * or consequential damages, which may result from the use of the PNG
+ * Reference Library, even if advised of the possibility of such damage.
+ *
+ * Permission is hereby granted to use, copy, modify, and distribute this
+ * source code, or portions hereof, for any purpose, without fee, subject
+ * to the following restrictions:
+ *
+ * 1. The origin of this source code must not be misrepresented.
+ *
+ * 2. Altered versions must be plainly marked as such and must not
+ * be misrepresented as being the original source.
+ *
+ * 3. This Copyright notice may not be removed or altered from any
+ * source or altered source distribution.
+ *
+ * The Contributing Authors and Group 42, Inc. specifically permit, without
+ * fee, and encourage the use of this source code as a component to
+ * supporting the PNG file format in commercial products. If you use this
+ * source code in a product, acknowledgment is not required but would be
+ * appreciated.
+ *
+ * END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.
+ */
+
+/*
+ * A "png_get_copyright" function is available, for convenient use in "about"
+ * boxes and the like:
+ *
+ * printf("%s", png_get_copyright(NULL));
+ *
+ * Also, the PNG logo (in PNG format, of course) is supplied in the
+ * files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
+ */
+
+/*
+ * Libpng is OSI Certified Open Source Software. OSI Certified Open Source is
+ * a certification mark of the Open Source Initiative. OSI has not addressed
+ * the additional disclaimers inserted at version 1.0.7.
+ */
+
+/*
+ * The contributing authors would like to thank all those who helped
+ * with testing, bug fixes, and patience. This wouldn't have been
+ * possible without all of you.
+ *
+ * Thanks to Frank J. T. Wojcik for helping with the documentation.
+ */
+
+/* Note about libpng version numbers:
+ *
+ * Due to various miscommunications, unforeseen code incompatibilities
+ * and occasional factors outside the authors' control, version numbering
+ * on the library has not always been consistent and straightforward.
+ * The following table summarizes matters since version 0.89c, which was
+ * the first widely used release:
+ *
+ * source png.h png.h shared-lib
+ * version string int version
+ * ------- ------ ----- ----------
+ * 0.89c "1.0 beta 3" 0.89 89 1.0.89
+ * 0.90 "1.0 beta 4" 0.90 90 0.90 [should have been 2.0.90]
+ * 0.95 "1.0 beta 5" 0.95 95 0.95 [should have been 2.0.95]
+ * 0.96 "1.0 beta 6" 0.96 96 0.96 [should have been 2.0.96]
+ * 0.97b "1.00.97 beta 7" 1.00.97 97 1.0.1 [should have been 2.0.97]
+ * 0.97c 0.97 97 2.0.97
+ * 0.98 0.98 98 2.0.98
+ * 0.99 0.99 98 2.0.99
+ * 0.99a-m 0.99 99 2.0.99
+ * 1.00 1.00 100 2.1.0 [100 should be 10000]
+ * 1.0.0 (from here on, the 100 2.1.0 [100 should be 10000]
+ * 1.0.1 png.h string is 10001 2.1.0
+ * 1.0.1a-e identical to the 10002 from here on, the shared library
+ * 1.0.2 source version) 10002 is 2.V where V is the source code
+ * 1.0.2a-b 10003 version, except as noted.
+ * 1.0.3 10003
+ * 1.0.3a-d 10004
+ * 1.0.4 10004
+ * 1.0.4a-f 10005
+ * 1.0.5 (+ 2 patches) 10005
+ * 1.0.5a-d 10006
+ * 1.0.5e-r 10100 (not source compatible)
+ * 1.0.5s-v 10006 (not binary compatible)
+ * 1.0.6 (+ 3 patches) 10006 (still binary incompatible)
+ * 1.0.6d-f 10007 (still binary incompatible)
+ * 1.0.6g 10007
+ * 1.0.6h 10007 10.6h (testing xy.z so-numbering)
+ * 1.0.6i 10007 10.6i
+ * 1.0.6j 10007 2.1.0.6j (incompatible with 1.0.0)
+ * 1.0.7beta11-14 DLLNUM 10007 2.1.0.7beta11-14 (binary compatible)
+ * 1.0.7beta15-18 1 10007 2.1.0.7beta15-18 (binary compatible)
+ * 1.0.7rc1-2 1 10007 2.1.0.7rc1-2 (binary compatible)
+ * 1.0.7 1 10007 (still compatible)
+ * ...
+ * 1.0.19 10 10019 10.so.0.19[.0]
+ * ...
+ * 1.2.53 13 10253 12.so.0.53[.0]
+ * ...
+ * 1.5.23 15 10523 15.so.15.23[.0]
+ * ...
+ * 1.6.20 16 10620 16.so.16.20[.0]
+ *
+ * Henceforth the source version will match the shared-library major
+ * and minor numbers; the shared-library major version number will be
+ * used for changes in backward compatibility, as it is intended. The
+ * PNG_LIBPNG_VER macro, which is not used within libpng but is available
+ * for applications, is an unsigned integer of the form xyyzz corresponding
+ * to the source version x.y.z (leading zeros in y and z). Beta versions
+ * were given the previous public release number plus a letter, until
+ * version 1.0.6j; from then on they were given the upcoming public
+ * release number plus "betaNN" or "rcNN".
+ *
+ * Binary incompatibility exists only when applications make direct access
+ * to the info_ptr or png_ptr members through png.h, and the compiled
+ * application is loaded with a different version of the library.
+ *
+ * DLLNUM will change each time there are forward or backward changes
+ * in binary compatibility (e.g., when a new feature is added).
+ *
+ * See libpng.txt or libpng.3 for more information. The PNG specification
+ * is available as a W3C Recommendation and as an ISO Specification,
+ * <http://www.w3.org/TR/2003/REC-PNG-20031110/
+ */
+
+/*
+ * Y2K compliance in libpng:
+ * =========================
+ *
+ * December 3, 2015
+ *
+ * Since the PNG Development group is an ad-hoc body, we can't make
+ * an official declaration.
+ *
+ * This is your unofficial assurance that libpng from version 0.71 and
+ * upward through 1.6.20 are Y2K compliant. It is my belief that
+ * earlier versions were also Y2K compliant.
+ *
+ * Libpng only has two year fields. One is a 2-byte unsigned integer
+ * that will hold years up to 65535. The other, which is deprecated,
+ * holds the date in text format, and will hold years up to 9999.
+ *
+ * The integer is
+ * "png_uint_16 year" in png_time_struct.
+ *
+ * The string is
+ * "char time_buffer[29]" in png_struct. This is no longer used
+ * in libpng-1.6.x and will be removed from libpng-1.7.0.
+ *
+ * There are seven time-related functions:
+ * png.c: png_convert_to_rfc_1123_buffer() in png.c
+ * (formerly png_convert_to_rfc_1123() prior to libpng-1.5.x and
+ * png_convert_to_rfc_1152() in error prior to libpng-0.98)
+ * png_convert_from_struct_tm() in pngwrite.c, called in pngwrite.c
+ * png_convert_from_time_t() in pngwrite.c
+ * png_get_tIME() in pngget.c
+ * png_handle_tIME() in pngrutil.c, called in pngread.c
+ * png_set_tIME() in pngset.c
+ * png_write_tIME() in pngwutil.c, called in pngwrite.c
+ *
+ * All handle dates properly in a Y2K environment. The
+ * png_convert_from_time_t() function calls gmtime() to convert from system
+ * clock time, which returns (year - 1900), which we properly convert to
+ * the full 4-digit year. There is a possibility that libpng applications
+ * are not passing 4-digit years into the png_convert_to_rfc_1123_buffer()
+ * function, or that they are incorrectly passing only a 2-digit year
+ * instead of "year - 1900" into the png_convert_from_struct_tm() function,
+ * but this is not under our control. The libpng documentation has always
+ * stated that it works with 4-digit years, and the APIs have been
+ * documented as such.
+ *
+ * The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned
+ * integer to hold the year, and can hold years as large as 65535.
+ *
+ * zlib, upon which libpng depends, is also Y2K compliant. It contains
+ * no date-related code.
+ *
+ * Glenn Randers-Pehrson
+ * libpng maintainer
+ * PNG Development Group
+ */
+
+#ifndef PNG_H
+#define PNG_H
+
+/* This is not the place to learn how to use libpng. The file libpng-manual.txt
+ * describes how to use libpng, and the file example.c summarizes it
+ * with some code on which to build. This file is useful for looking
+ * at the actual function definitions and structure components. If that
+ * file has been stripped from your copy of libpng, you can find it at
+ * <http://www.libpng.org/pub/png/libpng-manual.txt>
+ *
+ * If you just need to read a PNG file and don't want to read the documentation
+ * skip to the end of this file and read the section entitled 'simplified API'.
+ */
+
+/* Version information for png.h - this should match the version in png.c */
+#define PNG_LIBPNG_VER_STRING "1.6.20"
+#define PNG_HEADER_VERSION_STRING \
+ " libpng version 1.6.20 - December 3, 2015\n"
+
+#define PNG_LIBPNG_VER_SONUM 16
+#define PNG_LIBPNG_VER_DLLNUM 16
+
+/* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
+#define PNG_LIBPNG_VER_MAJOR 1
+#define PNG_LIBPNG_VER_MINOR 6
+#define PNG_LIBPNG_VER_RELEASE 20
+
+/* This should match the numeric part of the final component of
+ * PNG_LIBPNG_VER_STRING, omitting any leading zero:
+ */
+
+#define PNG_LIBPNG_VER_BUILD 0
+
+/* Release Status */
+#define PNG_LIBPNG_BUILD_ALPHA 1
+#define PNG_LIBPNG_BUILD_BETA 2
+#define PNG_LIBPNG_BUILD_RC 3
+#define PNG_LIBPNG_BUILD_STABLE 4
+#define PNG_LIBPNG_BUILD_RELEASE_STATUS_MASK 7
+
+/* Release-Specific Flags */
+#define PNG_LIBPNG_BUILD_PATCH 8 /* Can be OR'ed with
+ PNG_LIBPNG_BUILD_STABLE only */
+#define PNG_LIBPNG_BUILD_PRIVATE 16 /* Cannot be OR'ed with
+ PNG_LIBPNG_BUILD_SPECIAL */
+#define PNG_LIBPNG_BUILD_SPECIAL 32 /* Cannot be OR'ed with
+ PNG_LIBPNG_BUILD_PRIVATE */
+
+#define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_STABLE
+
+/* Careful here. At one time, Guy wanted to use 082, but that would be octal.
+ * We must not include leading zeros.
+ * Versions 0.7 through 1.0.0 were in the range 0 to 100 here (only
+ * version 1.0.0 was mis-numbered 100 instead of 10000). From
+ * version 1.0.1 it's xxyyzz, where x=major, y=minor, z=release
+ */
+#define PNG_LIBPNG_VER 10620 /* 1.6.20 */
+
+/* Library configuration: these options cannot be changed after
+ * the library has been built.
+ */
+#ifndef PNGLCONF_H
+ /* If pnglibconf.h is missing, you can
+ * copy scripts/pnglibconf.h.prebuilt to pnglibconf.h
+ */
+# include "pnglibconf.h"
+#endif
+
+#ifndef PNG_VERSION_INFO_ONLY
+ /* Machine specific configuration. */
+# include "pngconf.h"
+#endif
+
+/*
+ * Added at libpng-1.2.8
+ *
+ * Ref MSDN: Private as priority over Special
+ * VS_FF_PRIVATEBUILD File *was not* built using standard release
+ * procedures. If this value is given, the StringFileInfo block must
+ * contain a PrivateBuild string.
+ *
+ * VS_FF_SPECIALBUILD File *was* built by the original company using
+ * standard release procedures but is a variation of the standard
+ * file of the same version number. If this value is given, the
+ * StringFileInfo block must contain a SpecialBuild string.
+ */
+
+#ifdef PNG_USER_PRIVATEBUILD /* From pnglibconf.h */
+# define PNG_LIBPNG_BUILD_TYPE \
+ (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_PRIVATE)
+#else
+# ifdef PNG_LIBPNG_SPECIALBUILD
+# define PNG_LIBPNG_BUILD_TYPE \
+ (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_SPECIAL)
+# else
+# define PNG_LIBPNG_BUILD_TYPE (PNG_LIBPNG_BUILD_BASE_TYPE)
+# endif
+#endif
+
+#ifndef PNG_VERSION_INFO_ONLY
+
+/* Inhibit C++ name-mangling for libpng functions but not for system calls. */
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+/* Version information for C files, stored in png.c. This had better match
+ * the version above.
+ */
+#define png_libpng_ver png_get_header_ver(NULL)
+
+/* This file is arranged in several sections:
+ *
+ * 1. [omitted]
+ * 2. Any configuration options that can be specified by for the application
+ * code when it is built. (Build time configuration is in pnglibconf.h)
+ * 3. Type definitions (base types are defined in pngconf.h), structure
+ * definitions.
+ * 4. Exported library functions.
+ * 5. Simplified API.
+ * 6. Implementation options.
+ *
+ * The library source code has additional files (principally pngpriv.h) that
+ * allow configuration of the library.
+ */
+
+/* Section 1: [omitted] */
+
+/* Section 2: run time configuration
+ * See pnglibconf.h for build time configuration
+ *
+ * Run time configuration allows the application to choose between
+ * implementations of certain arithmetic APIs. The default is set
+ * at build time and recorded in pnglibconf.h, but it is safe to
+ * override these (and only these) settings. Note that this won't
+ * change what the library does, only application code, and the
+ * settings can (and probably should) be made on a per-file basis
+ * by setting the #defines before including png.h
+ *
+ * Use macros to read integers from PNG data or use the exported
+ * functions?
+ * PNG_USE_READ_MACROS: use the macros (see below) Note that
+ * the macros evaluate their argument multiple times.
+ * PNG_NO_USE_READ_MACROS: call the relevant library function.
+ *
+ * Use the alternative algorithm for compositing alpha samples that
+ * does not use division?
+ * PNG_READ_COMPOSITE_NODIV_SUPPORTED: use the 'no division'
+ * algorithm.
+ * PNG_NO_READ_COMPOSITE_NODIV: use the 'division' algorithm.
+ *
+ * How to handle benign errors if PNG_ALLOW_BENIGN_ERRORS is
+ * false?
+ * PNG_ALLOW_BENIGN_ERRORS: map calls to the benign error
+ * APIs to png_warning.
+ * Otherwise the calls are mapped to png_error.
+ */
+
+/* Section 3: type definitions, including structures and compile time
+ * constants.
+ * See pngconf.h for base types that vary by machine/system
+ */
+
+/* This triggers a compiler error in png.c, if png.c and png.h
+ * do not agree upon the version number.
+ */
+typedef char* png_libpng_version_1_6_20;
+
+/* Basic control structions. Read libpng-manual.txt or libpng.3 for more info.
+ *
+ * png_struct is the cache of information used while reading or writing a single
+ * PNG file. One of these is always required, although the simplified API
+ * (below) hides the creation and destruction of it.
+ */
+typedef struct png_struct_def png_struct;
+typedef const png_struct * png_const_structp;
+typedef png_struct * png_structp;
+typedef png_struct * * png_structpp;
+
+/* png_info contains information read from or to be written to a PNG file. One
+ * or more of these must exist while reading or creating a PNG file. The
+ * information is not used by libpng during read but is used to control what
+ * gets written when a PNG file is created. "png_get_" function calls read
+ * information during read and "png_set_" functions calls write information
+ * when creating a PNG.
+ * been moved into a separate header file that is not accessible to
+ * applications. Read libpng-manual.txt or libpng.3 for more info.
+ */
+typedef struct png_info_def png_info;
+typedef png_info * png_infop;
+typedef const png_info * png_const_infop;
+typedef png_info * * png_infopp;
+
+/* Types with names ending 'p' are pointer types. The corresponding types with
+ * names ending 'rp' are identical pointer types except that the pointer is
+ * marked 'restrict', which means that it is the only pointer to the object
+ * passed to the function. Applications should not use the 'restrict' types;
+ * it is always valid to pass 'p' to a pointer with a function argument of the
+ * corresponding 'rp' type. Different compilers have different rules with
+ * regard to type matching in the presence of 'restrict'. For backward
+ * compatibility libpng callbacks never have 'restrict' in their parameters and,
+ * consequentially, writing portable application code is extremely difficult if
+ * an attempt is made to use 'restrict'.
+ */
+typedef png_struct * PNG_RESTRICT png_structrp;
+typedef const png_struct * PNG_RESTRICT png_const_structrp;
+typedef png_info * PNG_RESTRICT png_inforp;
+typedef const png_info * PNG_RESTRICT png_const_inforp;
+
+/* Three color definitions. The order of the red, green, and blue, (and the
+ * exact size) is not important, although the size of the fields need to
+ * be png_byte or png_uint_16 (as defined below).
+ */
+typedef struct png_color_struct
+{
+ png_byte red;
+ png_byte green;
+ png_byte blue;
+} png_color;
+typedef png_color * png_colorp;
+typedef const png_color * png_const_colorp;
+typedef png_color * * png_colorpp;
+
+typedef struct png_color_16_struct
+{
+ png_byte index; /* used for palette files */
+ png_uint_16 red; /* for use in red green blue files */
+ png_uint_16 green;
+ png_uint_16 blue;
+ png_uint_16 gray; /* for use in grayscale files */
+} png_color_16;
+typedef png_color_16 * png_color_16p;
+typedef const png_color_16 * png_const_color_16p;
+typedef png_color_16 * * png_color_16pp;
+
+typedef struct png_color_8_struct
+{
+ png_byte red; /* for use in red green blue files */
+ png_byte green;
+ png_byte blue;
+ png_byte gray; /* for use in grayscale files */
+ png_byte alpha; /* for alpha channel files */
+} png_color_8;
+typedef png_color_8 * png_color_8p;
+typedef const png_color_8 * png_const_color_8p;
+typedef png_color_8 * * png_color_8pp;
+
+/*
+ * The following two structures are used for the in-core representation
+ * of sPLT chunks.
+ */
+typedef struct png_sPLT_entry_struct
+{
+ png_uint_16 red;
+ png_uint_16 green;
+ png_uint_16 blue;
+ png_uint_16 alpha;
+ png_uint_16 frequency;
+} png_sPLT_entry;
+typedef png_sPLT_entry * png_sPLT_entryp;
+typedef const png_sPLT_entry * png_const_sPLT_entryp;
+typedef png_sPLT_entry * * png_sPLT_entrypp;
+
+/* When the depth of the sPLT palette is 8 bits, the color and alpha samples
+ * occupy the LSB of their respective members, and the MSB of each member
+ * is zero-filled. The frequency member always occupies the full 16 bits.
+ */
+
+typedef struct png_sPLT_struct
+{
+ png_charp name; /* palette name */
+ png_byte depth; /* depth of palette samples */
+ png_sPLT_entryp entries; /* palette entries */
+ png_int_32 nentries; /* number of palette entries */
+} png_sPLT_t;
+typedef png_sPLT_t * png_sPLT_tp;
+typedef const png_sPLT_t * png_const_sPLT_tp;
+typedef png_sPLT_t * * png_sPLT_tpp;
+
+#ifdef PNG_TEXT_SUPPORTED
+/* png_text holds the contents of a text/ztxt/itxt chunk in a PNG file,
+ * and whether that contents is compressed or not. The "key" field
+ * points to a regular zero-terminated C string. The "text" fields can be a
+ * regular C string, an empty string, or a NULL pointer.
+ * However, the structure returned by png_get_text() will always contain
+ * the "text" field as a regular zero-terminated C string (possibly
+ * empty), never a NULL pointer, so it can be safely used in printf() and
+ * other string-handling functions. Note that the "itxt_length", "lang", and
+ * "lang_key" members of the structure only exist when the library is built
+ * with iTXt chunk support. Prior to libpng-1.4.0 the library was built by
+ * default without iTXt support. Also note that when iTXt *is* supported,
+ * the "lang" and "lang_key" fields contain NULL pointers when the
+ * "compression" field contains * PNG_TEXT_COMPRESSION_NONE or
+ * PNG_TEXT_COMPRESSION_zTXt. Note that the "compression value" is not the
+ * same as what appears in the PNG tEXt/zTXt/iTXt chunk's "compression flag"
+ * which is always 0 or 1, or its "compression method" which is always 0.
+ */
+typedef struct png_text_struct
+{
+ int compression; /* compression value:
+ -1: tEXt, none
+ 0: zTXt, deflate
+ 1: iTXt, none
+ 2: iTXt, deflate */
+ png_charp key; /* keyword, 1-79 character description of "text" */
+ png_charp text; /* comment, may be an empty string (ie "")
+ or a NULL pointer */
+ png_size_t text_length; /* length of the text string */
+ png_size_t itxt_length; /* length of the itxt string */
+ png_charp lang; /* language code, 0-79 characters
+ or a NULL pointer */
+ png_charp lang_key; /* keyword translated UTF-8 string, 0 or more
+ chars or a NULL pointer */
+} png_text;
+typedef png_text * png_textp;
+typedef const png_text * png_const_textp;
+typedef png_text * * png_textpp;
+#endif
+
+/* Supported compression types for text in PNG files (tEXt, and zTXt).
+ * The values of the PNG_TEXT_COMPRESSION_ defines should NOT be changed. */
+#define PNG_TEXT_COMPRESSION_NONE_WR -3
+#define PNG_TEXT_COMPRESSION_zTXt_WR -2
+#define PNG_TEXT_COMPRESSION_NONE -1
+#define PNG_TEXT_COMPRESSION_zTXt 0
+#define PNG_ITXT_COMPRESSION_NONE 1
+#define PNG_ITXT_COMPRESSION_zTXt 2
+#define PNG_TEXT_COMPRESSION_LAST 3 /* Not a valid value */
+
+/* png_time is a way to hold the time in an machine independent way.
+ * Two conversions are provided, both from time_t and struct tm. There
+ * is no portable way to convert to either of these structures, as far
+ * as I know. If you know of a portable way, send it to me. As a side
+ * note - PNG has always been Year 2000 compliant!
+ */
+typedef struct png_time_struct
+{
+ png_uint_16 year; /* full year, as in, 1995 */
+ png_byte month; /* month of year, 1 - 12 */
+ png_byte day; /* day of month, 1 - 31 */
+ png_byte hour; /* hour of day, 0 - 23 */
+ png_byte minute; /* minute of hour, 0 - 59 */
+ png_byte second; /* second of minute, 0 - 60 (for leap seconds) */
+} png_time;
+typedef png_time * png_timep;
+typedef const png_time * png_const_timep;
+typedef png_time * * png_timepp;
+
+#if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) ||\
+ defined(PNG_USER_CHUNKS_SUPPORTED)
+/* png_unknown_chunk is a structure to hold queued chunks for which there is
+ * no specific support. The idea is that we can use this to queue
+ * up private chunks for output even though the library doesn't actually
+ * know about their semantics.
+ *
+ * The data in the structure is set by libpng on read and used on write.
+ */
+typedef struct png_unknown_chunk_t
+{
+ png_byte name[5]; /* Textual chunk name with '\0' terminator */
+ png_byte *data; /* Data, should not be modified on read! */
+ png_size_t size;
+
+ /* On write 'location' must be set using the flag values listed below.
+ * Notice that on read it is set by libpng however the values stored have
+ * more bits set than are listed below. Always treat the value as a
+ * bitmask. On write set only one bit - setting multiple bits may cause the
+ * chunk to be written in multiple places.
+ */
+ png_byte location; /* mode of operation at read time */
+}
+png_unknown_chunk;
+
+typedef png_unknown_chunk * png_unknown_chunkp;
+typedef const png_unknown_chunk * png_const_unknown_chunkp;
+typedef png_unknown_chunk * * png_unknown_chunkpp;
+#endif
+
+/* Flag values for the unknown chunk location byte. */
+#define PNG_HAVE_IHDR 0x01
+#define PNG_HAVE_PLTE 0x02
+#define PNG_AFTER_IDAT 0x08
+
+/* Maximum positive integer used in PNG is (2^31)-1 */
+#define PNG_UINT_31_MAX ((png_uint_32)0x7fffffffL)
+#define PNG_UINT_32_MAX ((png_uint_32)(-1))
+#define PNG_SIZE_MAX ((png_size_t)(-1))
+
+/* These are constants for fixed point values encoded in the
+ * PNG specification manner (x100000)
+ */
+#define PNG_FP_1 100000
+#define PNG_FP_HALF 50000
+#define PNG_FP_MAX ((png_fixed_point)0x7fffffffL)
+#define PNG_FP_MIN (-PNG_FP_MAX)
+
+/* These describe the color_type field in png_info. */
+/* color type masks */
+#define PNG_COLOR_MASK_PALETTE 1
+#define PNG_COLOR_MASK_COLOR 2
+#define PNG_COLOR_MASK_ALPHA 4
+
+/* color types. Note that not all combinations are legal */
+#define PNG_COLOR_TYPE_GRAY 0
+#define PNG_COLOR_TYPE_PALETTE (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)
+#define PNG_COLOR_TYPE_RGB (PNG_COLOR_MASK_COLOR)
+#define PNG_COLOR_TYPE_RGB_ALPHA (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA)
+#define PNG_COLOR_TYPE_GRAY_ALPHA (PNG_COLOR_MASK_ALPHA)
+/* aliases */
+#define PNG_COLOR_TYPE_RGBA PNG_COLOR_TYPE_RGB_ALPHA
+#define PNG_COLOR_TYPE_GA PNG_COLOR_TYPE_GRAY_ALPHA
+
+/* This is for compression type. PNG 1.0-1.2 only define the single type. */
+#define PNG_COMPRESSION_TYPE_BASE 0 /* Deflate method 8, 32K window */
+#define PNG_COMPRESSION_TYPE_DEFAULT PNG_COMPRESSION_TYPE_BASE
+
+/* This is for filter type. PNG 1.0-1.2 only define the single type. */
+#define PNG_FILTER_TYPE_BASE 0 /* Single row per-byte filtering */
+#define PNG_INTRAPIXEL_DIFFERENCING 64 /* Used only in MNG datastreams */
+#define PNG_FILTER_TYPE_DEFAULT PNG_FILTER_TYPE_BASE
+
+/* These are for the interlacing type. These values should NOT be changed. */
+#define PNG_INTERLACE_NONE 0 /* Non-interlaced image */
+#define PNG_INTERLACE_ADAM7 1 /* Adam7 interlacing */
+#define PNG_INTERLACE_LAST 2 /* Not a valid value */
+
+/* These are for the oFFs chunk. These values should NOT be changed. */
+#define PNG_OFFSET_PIXEL 0 /* Offset in pixels */
+#define PNG_OFFSET_MICROMETER 1 /* Offset in micrometers (1/10^6 meter) */
+#define PNG_OFFSET_LAST 2 /* Not a valid value */
+
+/* These are for the pCAL chunk. These values should NOT be changed. */
+#define PNG_EQUATION_LINEAR 0 /* Linear transformation */
+#define PNG_EQUATION_BASE_E 1 /* Exponential base e transform */
+#define PNG_EQUATION_ARBITRARY 2 /* Arbitrary base exponential transform */
+#define PNG_EQUATION_HYPERBOLIC 3 /* Hyperbolic sine transformation */
+#define PNG_EQUATION_LAST 4 /* Not a valid value */
+
+/* These are for the sCAL chunk. These values should NOT be changed. */
+#define PNG_SCALE_UNKNOWN 0 /* unknown unit (image scale) */
+#define PNG_SCALE_METER 1 /* meters per pixel */
+#define PNG_SCALE_RADIAN 2 /* radians per pixel */
+#define PNG_SCALE_LAST 3 /* Not a valid value */
+
+/* These are for the pHYs chunk. These values should NOT be changed. */
+#define PNG_RESOLUTION_UNKNOWN 0 /* pixels/unknown unit (aspect ratio) */
+#define PNG_RESOLUTION_METER 1 /* pixels/meter */
+#define PNG_RESOLUTION_LAST 2 /* Not a valid value */
+
+/* These are for the sRGB chunk. These values should NOT be changed. */
+#define PNG_sRGB_INTENT_PERCEPTUAL 0
+#define PNG_sRGB_INTENT_RELATIVE 1
+#define PNG_sRGB_INTENT_SATURATION 2
+#define PNG_sRGB_INTENT_ABSOLUTE 3
+#define PNG_sRGB_INTENT_LAST 4 /* Not a valid value */
+
+/* This is for text chunks */
+#define PNG_KEYWORD_MAX_LENGTH 79
+
+/* Maximum number of entries in PLTE/sPLT/tRNS arrays */
+#define PNG_MAX_PALETTE_LENGTH 256
+
+/* These determine if an ancillary chunk's data has been successfully read
+ * from the PNG header, or if the application has filled in the corresponding
+ * data in the info_struct to be written into the output file. The values
+ * of the PNG_INFO_<chunk> defines should NOT be changed.
+ */
+#define PNG_INFO_gAMA 0x0001
+#define PNG_INFO_sBIT 0x0002
+#define PNG_INFO_cHRM 0x0004
+#define PNG_INFO_PLTE 0x0008
+#define PNG_INFO_tRNS 0x0010
+#define PNG_INFO_bKGD 0x0020
+#define PNG_INFO_hIST 0x0040
+#define PNG_INFO_pHYs 0x0080
+#define PNG_INFO_oFFs 0x0100
+#define PNG_INFO_tIME 0x0200
+#define PNG_INFO_pCAL 0x0400
+#define PNG_INFO_sRGB 0x0800 /* GR-P, 0.96a */
+#define PNG_INFO_iCCP 0x1000 /* ESR, 1.0.6 */
+#define PNG_INFO_sPLT 0x2000 /* ESR, 1.0.6 */
+#define PNG_INFO_sCAL 0x4000 /* ESR, 1.0.6 */
+#if INT_MAX >= 0x8000 /* else this might break */
+#define PNG_INFO_IDAT 0x8000 /* ESR, 1.0.6 */
+#endif
+
+/* This is used for the transformation routines, as some of them
+ * change these values for the row. It also should enable using
+ * the routines for other purposes.
+ */
+typedef struct png_row_info_struct
+{
+ png_uint_32 width; /* width of row */
+ png_size_t rowbytes; /* number of bytes in row */
+ png_byte color_type; /* color type of row */
+ png_byte bit_depth; /* bit depth of row */
+ png_byte channels; /* number of channels (1, 2, 3, or 4) */
+ png_byte pixel_depth; /* bits per pixel (depth * channels) */
+} png_row_info;
+
+typedef png_row_info * png_row_infop;
+typedef png_row_info * * png_row_infopp;
+
+/* These are the function types for the I/O functions and for the functions
+ * that allow the user to override the default I/O functions with his or her
+ * own. The png_error_ptr type should match that of user-supplied warning
+ * and error functions, while the png_rw_ptr type should match that of the
+ * user read/write data functions. Note that the 'write' function must not
+ * modify the buffer it is passed. The 'read' function, on the other hand, is
+ * expected to return the read data in the buffer.
+ */
+typedef PNG_CALLBACK(void, *png_error_ptr, (png_structp, png_const_charp));
+typedef PNG_CALLBACK(void, *png_rw_ptr, (png_structp, png_bytep, png_size_t));
+typedef PNG_CALLBACK(void, *png_flush_ptr, (png_structp));
+typedef PNG_CALLBACK(void, *png_read_status_ptr, (png_structp, png_uint_32,
+ int));
+typedef PNG_CALLBACK(void, *png_write_status_ptr, (png_structp, png_uint_32,
+ int));
+
+#ifdef PNG_INDEX_SUPPORTED
+typedef PNG_CALLBACK(void, *png_seek_ptr, (png_structp, png_uint_32));
+#endif
+
+#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
+typedef PNG_CALLBACK(void, *png_progressive_info_ptr, (png_structp, png_infop));
+typedef PNG_CALLBACK(void, *png_progressive_end_ptr, (png_structp, png_infop));
+
+/* The following callback receives png_uint_32 row_number, int pass for the
+ * png_bytep data of the row. When transforming an interlaced image the
+ * row number is the row number within the sub-image of the interlace pass, so
+ * the value will increase to the height of the sub-image (not the full image)
+ * then reset to 0 for the next pass.
+ *
+ * Use PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
+ * find the output pixel (x,y) given an interlaced sub-image pixel
+ * (row,col,pass). (See below for these macros.)
+ */
+typedef PNG_CALLBACK(void, *png_progressive_row_ptr, (png_structp, png_bytep,
+ png_uint_32, int));
+#endif
+
+#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
+ defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
+typedef PNG_CALLBACK(void, *png_user_transform_ptr, (png_structp, png_row_infop,
+ png_bytep));
+#endif
+
+#ifdef PNG_USER_CHUNKS_SUPPORTED
+typedef PNG_CALLBACK(int, *png_user_chunk_ptr, (png_structp,
+ png_unknown_chunkp));
+#endif
+#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
+/* not used anywhere */
+/* typedef PNG_CALLBACK(void, *png_unknown_chunk_ptr, (png_structp)); */
+#endif
+
+#ifdef PNG_SETJMP_SUPPORTED
+/* This must match the function definition in <setjmp.h>, and the application
+ * must include this before png.h to obtain the definition of jmp_buf. The
+ * function is required to be PNG_NORETURN, but this is not checked. If the
+ * function does return the application will crash via an abort() or similar
+ * system level call.
+ *
+ * If you get a warning here while building the library you may need to make
+ * changes to ensure that pnglibconf.h records the calling convention used by
+ * your compiler. This may be very difficult - try using a different compiler
+ * to build the library!
+ */
+PNG_FUNCTION(void, (PNGCAPI *png_longjmp_ptr), PNGARG((jmp_buf, int)), typedef);
+#endif
+
+/* Transform masks for the high-level interface */
+#define PNG_TRANSFORM_IDENTITY 0x0000 /* read and write */
+#define PNG_TRANSFORM_STRIP_16 0x0001 /* read only */
+#define PNG_TRANSFORM_STRIP_ALPHA 0x0002 /* read only */
+#define PNG_TRANSFORM_PACKING 0x0004 /* read and write */
+#define PNG_TRANSFORM_PACKSWAP 0x0008 /* read and write */
+#define PNG_TRANSFORM_EXPAND 0x0010 /* read only */
+#define PNG_TRANSFORM_INVERT_MONO 0x0020 /* read and write */
+#define PNG_TRANSFORM_SHIFT 0x0040 /* read and write */
+#define PNG_TRANSFORM_BGR 0x0080 /* read and write */
+#define PNG_TRANSFORM_SWAP_ALPHA 0x0100 /* read and write */
+#define PNG_TRANSFORM_SWAP_ENDIAN 0x0200 /* read and write */
+#define PNG_TRANSFORM_INVERT_ALPHA 0x0400 /* read and write */
+#define PNG_TRANSFORM_STRIP_FILLER 0x0800 /* write only */
+/* Added to libpng-1.2.34 */
+#define PNG_TRANSFORM_STRIP_FILLER_BEFORE PNG_TRANSFORM_STRIP_FILLER
+#define PNG_TRANSFORM_STRIP_FILLER_AFTER 0x1000 /* write only */
+/* Added to libpng-1.4.0 */
+#define PNG_TRANSFORM_GRAY_TO_RGB 0x2000 /* read only */
+/* Added to libpng-1.5.4 */
+#define PNG_TRANSFORM_EXPAND_16 0x4000 /* read only */
+#if INT_MAX >= 0x8000 /* else this might break */
+#define PNG_TRANSFORM_SCALE_16 0x8000 /* read only */
+#endif
+
+/* Flags for MNG supported features */
+#define PNG_FLAG_MNG_EMPTY_PLTE 0x01
+#define PNG_FLAG_MNG_FILTER_64 0x04
+#define PNG_ALL_MNG_FEATURES 0x05
+
+/* NOTE: prior to 1.5 these functions had no 'API' style declaration,
+ * this allowed the zlib default functions to be used on Windows
+ * platforms. In 1.5 the zlib default malloc (which just calls malloc and
+ * ignores the first argument) should be completely compatible with the
+ * following.
+ */
+typedef PNG_CALLBACK(png_voidp, *png_malloc_ptr, (png_structp,
+ png_alloc_size_t));
+typedef PNG_CALLBACK(void, *png_free_ptr, (png_structp, png_voidp));
+
+/* Section 4: exported functions
+ * Here are the function definitions most commonly used. This is not
+ * the place to find out how to use libpng. See libpng-manual.txt for the
+ * full explanation, see example.c for the summary. This just provides
+ * a simple one line description of the use of each function.
+ *
+ * The PNG_EXPORT() and PNG_EXPORTA() macros used below are defined in
+ * pngconf.h and in the *.dfn files in the scripts directory.
+ *
+ * PNG_EXPORT(ordinal, type, name, (args));
+ *
+ * ordinal: ordinal that is used while building
+ * *.def files. The ordinal value is only
+ * relevant when preprocessing png.h with
+ * the *.dfn files for building symbol table
+ * entries, and are removed by pngconf.h.
+ * type: return type of the function
+ * name: function name
+ * args: function arguments, with types
+ *
+ * When we wish to append attributes to a function prototype we use
+ * the PNG_EXPORTA() macro instead.
+ *
+ * PNG_EXPORTA(ordinal, type, name, (args), attributes);
+ *
+ * ordinal, type, name, and args: same as in PNG_EXPORT().
+ * attributes: function attributes
+ */
+
+/* Returns the version number of the library */
+PNG_EXPORT(1, png_uint_32, png_access_version_number, (void));
+
+/* Tell lib we have already handled the first <num_bytes> magic bytes.
+ * Handling more than 8 bytes from the beginning of the file is an error.
+ */
+PNG_EXPORT(2, void, png_set_sig_bytes, (png_structrp png_ptr, int num_bytes));
+
+/* Check sig[start] through sig[start + num_to_check - 1] to see if it's a
+ * PNG file. Returns zero if the supplied bytes match the 8-byte PNG
+ * signature, and non-zero otherwise. Having num_to_check == 0 or
+ * start > 7 will always fail (ie return non-zero).
+ */
+PNG_EXPORT(3, int, png_sig_cmp, (png_const_bytep sig, png_size_t start,
+ png_size_t num_to_check));
+
+/* Simple signature checking function. This is the same as calling
+ * png_check_sig(sig, n) := !png_sig_cmp(sig, 0, n).
+ */
+#define png_check_sig(sig, n) !png_sig_cmp((sig), 0, (n))
+
+/* Allocate and initialize png_ptr struct for reading, and any other memory. */
+PNG_EXPORTA(4, png_structp, png_create_read_struct,
+ (png_const_charp user_png_ver, png_voidp error_ptr,
+ png_error_ptr error_fn, png_error_ptr warn_fn),
+ PNG_ALLOCATED);
+
+/* Allocate and initialize png_ptr struct for writing, and any other memory */
+PNG_EXPORTA(5, png_structp, png_create_write_struct,
+ (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
+ png_error_ptr warn_fn),
+ PNG_ALLOCATED);
+
+PNG_EXPORT(6, png_size_t, png_get_compression_buffer_size,
+ (png_const_structrp png_ptr));
+
+PNG_EXPORT(7, void, png_set_compression_buffer_size, (png_structrp png_ptr,
+ png_size_t size));
+
+/* Moved from pngconf.h in 1.4.0 and modified to ensure setjmp/longjmp
+ * match up.
+ */
+#ifdef PNG_SETJMP_SUPPORTED
+/* This function returns the jmp_buf built in to *png_ptr. It must be
+ * supplied with an appropriate 'longjmp' function to use on that jmp_buf
+ * unless the default error function is overridden in which case NULL is
+ * acceptable. The size of the jmp_buf is checked against the actual size
+ * allocated by the library - the call will return NULL on a mismatch
+ * indicating an ABI mismatch.
+ */
+PNG_EXPORT(8, jmp_buf*, png_set_longjmp_fn, (png_structrp png_ptr,
+ png_longjmp_ptr longjmp_fn, size_t jmp_buf_size));
+# define png_jmpbuf(png_ptr) \
+ (*png_set_longjmp_fn((png_ptr), longjmp, (sizeof (jmp_buf))))
+#else
+# define png_jmpbuf(png_ptr) \
+ (LIBPNG_WAS_COMPILED_WITH__PNG_NO_SETJMP)
+#endif
+/* This function should be used by libpng applications in place of
+ * longjmp(png_ptr->jmpbuf, val). If longjmp_fn() has been set, it
+ * will use it; otherwise it will call PNG_ABORT(). This function was
+ * added in libpng-1.5.0.
+ */
+PNG_EXPORTA(9, void, png_longjmp, (png_const_structrp png_ptr, int val),
+ PNG_NORETURN);
+
+#ifdef PNG_READ_SUPPORTED
+/* Reset the compression stream */
+PNG_EXPORTA(10, int, png_reset_zstream, (png_structrp png_ptr), PNG_DEPRECATED);
+#endif
+
+/* New functions added in libpng-1.0.2 (not enabled by default until 1.2.0) */
+#ifdef PNG_USER_MEM_SUPPORTED
+PNG_EXPORTA(11, png_structp, png_create_read_struct_2,
+ (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
+ png_error_ptr warn_fn,
+ png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn),
+ PNG_ALLOCATED);
+PNG_EXPORTA(12, png_structp, png_create_write_struct_2,
+ (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
+ png_error_ptr warn_fn,
+ png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn),
+ PNG_ALLOCATED);
+#endif
+
+/* Write the PNG file signature. */
+PNG_EXPORT(13, void, png_write_sig, (png_structrp png_ptr));
+
+/* Write a PNG chunk - size, type, (optional) data, CRC. */
+PNG_EXPORT(14, void, png_write_chunk, (png_structrp png_ptr, png_const_bytep
+ chunk_name, png_const_bytep data, png_size_t length));
+
+/* Write the start of a PNG chunk - length and chunk name. */
+PNG_EXPORT(15, void, png_write_chunk_start, (png_structrp png_ptr,
+ png_const_bytep chunk_name, png_uint_32 length));
+
+/* Write the data of a PNG chunk started with png_write_chunk_start(). */
+PNG_EXPORT(16, void, png_write_chunk_data, (png_structrp png_ptr,
+ png_const_bytep data, png_size_t length));
+
+/* Finish a chunk started with png_write_chunk_start() (includes CRC). */
+PNG_EXPORT(17, void, png_write_chunk_end, (png_structrp png_ptr));
+
+/* Allocate and initialize the info structure */
+PNG_EXPORTA(18, png_infop, png_create_info_struct, (png_const_structrp png_ptr),
+ PNG_ALLOCATED);
+
+/* DEPRECATED: this function allowed init structures to be created using the
+ * default allocation method (typically malloc). Use is deprecated in 1.6.0 and
+ * the API will be removed in the future.
+ */
+PNG_EXPORTA(19, void, png_info_init_3, (png_infopp info_ptr,
+ png_size_t png_info_struct_size), PNG_DEPRECATED);
+
+/* Writes all the PNG information before the image. */
+PNG_EXPORT(20, void, png_write_info_before_PLTE,
+ (png_structrp png_ptr, png_const_inforp info_ptr));
+PNG_EXPORT(21, void, png_write_info,
+ (png_structrp png_ptr, png_const_inforp info_ptr));
+
+#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
+/* Read the information before the actual image data. */
+PNG_EXPORT(22, void, png_read_info,
+ (png_structrp png_ptr, png_inforp info_ptr));
+#endif
+
+#ifdef PNG_TIME_RFC1123_SUPPORTED
+ /* Convert to a US string format: there is no localization support in this
+ * routine. The original implementation used a 29 character buffer in
+ * png_struct, this will be removed in future versions.
+ */
+#if PNG_LIBPNG_VER < 10700
+/* To do: remove this from libpng17 (and from libpng17/png.c and pngstruct.h) */
+PNG_EXPORTA(23, png_const_charp, png_convert_to_rfc1123, (png_structrp png_ptr,
+ png_const_timep ptime),PNG_DEPRECATED);
+#endif
+PNG_EXPORT(241, int, png_convert_to_rfc1123_buffer, (char out[29],
+ png_const_timep ptime));
+#endif
+
+#ifdef PNG_CONVERT_tIME_SUPPORTED
+/* Convert from a struct tm to png_time */
+PNG_EXPORT(24, void, png_convert_from_struct_tm, (png_timep ptime,
+ const struct tm * ttime));
+
+/* Convert from time_t to png_time. Uses gmtime() */
+PNG_EXPORT(25, void, png_convert_from_time_t, (png_timep ptime, time_t ttime));
+#endif /* CONVERT_tIME */
+
+#ifdef PNG_READ_EXPAND_SUPPORTED
+/* Expand data to 24-bit RGB, or 8-bit grayscale, with alpha if available. */
+PNG_EXPORT(26, void, png_set_expand, (png_structrp png_ptr));
+PNG_EXPORT(27, void, png_set_expand_gray_1_2_4_to_8, (png_structrp png_ptr));
+PNG_EXPORT(28, void, png_set_palette_to_rgb, (png_structrp png_ptr));
+PNG_EXPORT(29, void, png_set_tRNS_to_alpha, (png_structrp png_ptr));
+#endif
+
+#ifdef PNG_READ_EXPAND_16_SUPPORTED
+/* Expand to 16-bit channels, forces conversion of palette to RGB and expansion
+ * of a tRNS chunk if present.
+ */
+PNG_EXPORT(221, void, png_set_expand_16, (png_structrp png_ptr));
+#endif
+
+#if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
+/* Use blue, green, red order for pixels. */
+PNG_EXPORT(30, void, png_set_bgr, (png_structrp png_ptr));
+#endif
+
+#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
+/* Expand the grayscale to 24-bit RGB if necessary. */
+PNG_EXPORT(31, void, png_set_gray_to_rgb, (png_structrp png_ptr));
+#endif
+
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+/* Reduce RGB to grayscale. */
+#define PNG_ERROR_ACTION_NONE 1
+#define PNG_ERROR_ACTION_WARN 2
+#define PNG_ERROR_ACTION_ERROR 3
+#define PNG_RGB_TO_GRAY_DEFAULT (-1)/*for red/green coefficients*/
+
+PNG_FP_EXPORT(32, void, png_set_rgb_to_gray, (png_structrp png_ptr,
+ int error_action, double red, double green))
+PNG_FIXED_EXPORT(33, void, png_set_rgb_to_gray_fixed, (png_structrp png_ptr,
+ int error_action, png_fixed_point red, png_fixed_point green))
+
+PNG_EXPORT(34, png_byte, png_get_rgb_to_gray_status, (png_const_structrp
+ png_ptr));
+#endif
+
+#ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
+PNG_EXPORT(35, void, png_build_grayscale_palette, (int bit_depth,
+ png_colorp palette));
+#endif
+
+#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
+/* How the alpha channel is interpreted - this affects how the color channels
+ * of a PNG file are returned to the calling application when an alpha channel,
+ * or a tRNS chunk in a palette file, is present.
+ *
+ * This has no effect on the way pixels are written into a PNG output
+ * datastream. The color samples in a PNG datastream are never premultiplied
+ * with the alpha samples.
+ *
+ * The default is to return data according to the PNG specification: the alpha
+ * channel is a linear measure of the contribution of the pixel to the
+ * corresponding composited pixel, and the color channels are unassociated
+ * (not premultiplied). The gamma encoded color channels must be scaled
+ * according to the contribution and to do this it is necessary to undo
+ * the encoding, scale the color values, perform the composition and reencode
+ * the values. This is the 'PNG' mode.
+ *
+ * The alternative is to 'associate' the alpha with the color information by
+ * storing color channel values that have been scaled by the alpha.
+ * image. These are the 'STANDARD', 'ASSOCIATED' or 'PREMULTIPLIED' modes
+ * (the latter being the two common names for associated alpha color channels).
+ *
+ * For the 'OPTIMIZED' mode, a pixel is treated as opaque only if the alpha
+ * value is equal to the maximum value.
+ *
+ * The final choice is to gamma encode the alpha channel as well. This is
+ * broken because, in practice, no implementation that uses this choice
+ * correctly undoes the encoding before handling alpha composition. Use this
+ * choice only if other serious errors in the software or hardware you use
+ * mandate it; the typical serious error is for dark halos to appear around
+ * opaque areas of the composited PNG image because of arithmetic overflow.
+ *
+ * The API function png_set_alpha_mode specifies which of these choices to use
+ * with an enumerated 'mode' value and the gamma of the required output:
+ */
+#define PNG_ALPHA_PNG 0 /* according to the PNG standard */
+#define PNG_ALPHA_STANDARD 1 /* according to Porter/Duff */
+#define PNG_ALPHA_ASSOCIATED 1 /* as above; this is the normal practice */
+#define PNG_ALPHA_PREMULTIPLIED 1 /* as above */
+#define PNG_ALPHA_OPTIMIZED 2 /* 'PNG' for opaque pixels, else 'STANDARD' */
+#define PNG_ALPHA_BROKEN 3 /* the alpha channel is gamma encoded */
+
+PNG_FP_EXPORT(227, void, png_set_alpha_mode, (png_structrp png_ptr, int mode,
+ double output_gamma))
+PNG_FIXED_EXPORT(228, void, png_set_alpha_mode_fixed, (png_structrp png_ptr,
+ int mode, png_fixed_point output_gamma))
+#endif
+
+#if defined(PNG_GAMMA_SUPPORTED) || defined(PNG_READ_ALPHA_MODE_SUPPORTED)
+/* The output_gamma value is a screen gamma in libpng terminology: it expresses
+ * how to decode the output values, not how they are encoded.
+ */
+#define PNG_DEFAULT_sRGB -1 /* sRGB gamma and color space */
+#define PNG_GAMMA_MAC_18 -2 /* Old Mac '1.8' gamma and color space */
+#define PNG_GAMMA_sRGB 220000 /* Television standards--matches sRGB gamma */
+#define PNG_GAMMA_LINEAR PNG_FP_1 /* Linear */
+#endif
+
+/* The following are examples of calls to png_set_alpha_mode to achieve the
+ * required overall gamma correction and, where necessary, alpha
+ * premultiplication.
+ *
+ * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
+ * This is the default libpng handling of the alpha channel - it is not
+ * pre-multiplied into the color components. In addition the call states
+ * that the output is for a sRGB system and causes all PNG files without gAMA
+ * chunks to be assumed to be encoded using sRGB.
+ *
+ * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
+ * In this case the output is assumed to be something like an sRGB conformant
+ * display preceeded by a power-law lookup table of power 1.45. This is how
+ * early Mac systems behaved.
+ *
+ * png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_GAMMA_LINEAR);
+ * This is the classic Jim Blinn approach and will work in academic
+ * environments where everything is done by the book. It has the shortcoming
+ * of assuming that input PNG data with no gamma information is linear - this
+ * is unlikely to be correct unless the PNG files where generated locally.
+ * Most of the time the output precision will be so low as to show
+ * significant banding in dark areas of the image.
+ *
+ * png_set_expand_16(pp);
+ * png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_DEFAULT_sRGB);
+ * This is a somewhat more realistic Jim Blinn inspired approach. PNG files
+ * are assumed to have the sRGB encoding if not marked with a gamma value and
+ * the output is always 16 bits per component. This permits accurate scaling
+ * and processing of the data. If you know that your input PNG files were
+ * generated locally you might need to replace PNG_DEFAULT_sRGB with the
+ * correct value for your system.
+ *
+ * png_set_alpha_mode(pp, PNG_ALPHA_OPTIMIZED, PNG_DEFAULT_sRGB);
+ * If you just need to composite the PNG image onto an existing background
+ * and if you control the code that does this you can use the optimization
+ * setting. In this case you just copy completely opaque pixels to the
+ * output. For pixels that are not completely transparent (you just skip
+ * those) you do the composition math using png_composite or png_composite_16
+ * below then encode the resultant 8-bit or 16-bit values to match the output
+ * encoding.
+ *
+ * Other cases
+ * If neither the PNG nor the standard linear encoding work for you because
+ * of the software or hardware you use then you have a big problem. The PNG
+ * case will probably result in halos around the image. The linear encoding
+ * will probably result in a washed out, too bright, image (it's actually too
+ * contrasty.) Try the ALPHA_OPTIMIZED mode above - this will probably
+ * substantially reduce the halos. Alternatively try:
+ *
+ * png_set_alpha_mode(pp, PNG_ALPHA_BROKEN, PNG_DEFAULT_sRGB);
+ * This option will also reduce the halos, but there will be slight dark
+ * halos round the opaque parts of the image where the background is light.
+ * In the OPTIMIZED mode the halos will be light halos where the background
+ * is dark. Take your pick - the halos are unavoidable unless you can get
+ * your hardware/software fixed! (The OPTIMIZED approach is slightly
+ * faster.)
+ *
+ * When the default gamma of PNG files doesn't match the output gamma.
+ * If you have PNG files with no gamma information png_set_alpha_mode allows
+ * you to provide a default gamma, but it also sets the ouput gamma to the
+ * matching value. If you know your PNG files have a gamma that doesn't
+ * match the output you can take advantage of the fact that
+ * png_set_alpha_mode always sets the output gamma but only sets the PNG
+ * default if it is not already set:
+ *
+ * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
+ * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
+ * The first call sets both the default and the output gamma values, the
+ * second call overrides the output gamma without changing the default. This
+ * is easier than achieving the same effect with png_set_gamma. You must use
+ * PNG_ALPHA_PNG for the first call - internal checking in png_set_alpha will
+ * fire if more than one call to png_set_alpha_mode and png_set_background is
+ * made in the same read operation, however multiple calls with PNG_ALPHA_PNG
+ * are ignored.
+ */
+
+#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
+PNG_EXPORT(36, void, png_set_strip_alpha, (png_structrp png_ptr));
+#endif
+
+#if defined(PNG_READ_SWAP_ALPHA_SUPPORTED) || \
+ defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
+PNG_EXPORT(37, void, png_set_swap_alpha, (png_structrp png_ptr));
+#endif
+
+#if defined(PNG_READ_INVERT_ALPHA_SUPPORTED) || \
+ defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
+PNG_EXPORT(38, void, png_set_invert_alpha, (png_structrp png_ptr));
+#endif
+
+#if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
+/* Add a filler byte to 8-bit or 16-bit Gray or 24-bit or 48-bit RGB images. */
+PNG_EXPORT(39, void, png_set_filler, (png_structrp png_ptr, png_uint_32 filler,
+ int flags));
+/* The values of the PNG_FILLER_ defines should NOT be changed */
+# define PNG_FILLER_BEFORE 0
+# define PNG_FILLER_AFTER 1
+/* Add an alpha byte to 8-bit or 16-bit Gray or 24-bit or 48-bit RGB images. */
+PNG_EXPORT(40, void, png_set_add_alpha, (png_structrp png_ptr,
+ png_uint_32 filler, int flags));
+#endif /* READ_FILLER || WRITE_FILLER */
+
+#if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
+/* Swap bytes in 16-bit depth files. */
+PNG_EXPORT(41, void, png_set_swap, (png_structrp png_ptr));
+#endif
+
+#if defined(PNG_READ_PACK_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
+/* Use 1 byte per pixel in 1, 2, or 4-bit depth files. */
+PNG_EXPORT(42, void, png_set_packing, (png_structrp png_ptr));
+#endif
+
+#if defined(PNG_READ_PACKSWAP_SUPPORTED) || \
+ defined(PNG_WRITE_PACKSWAP_SUPPORTED)
+/* Swap packing order of pixels in bytes. */
+PNG_EXPORT(43, void, png_set_packswap, (png_structrp png_ptr));
+#endif
+
+#if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
+/* Converts files to legal bit depths. */
+PNG_EXPORT(44, void, png_set_shift, (png_structrp png_ptr, png_const_color_8p
+ true_bits));
+#endif
+
+#if defined(PNG_READ_INTERLACING_SUPPORTED) || \
+ defined(PNG_WRITE_INTERLACING_SUPPORTED)
+/* Have the code handle the interlacing. Returns the number of passes.
+ * MUST be called before png_read_update_info or png_start_read_image,
+ * otherwise it will not have the desired effect. Note that it is still
+ * necessary to call png_read_row or png_read_rows png_get_image_height
+ * times for each pass.
+*/
+PNG_EXPORT(45, int, png_set_interlace_handling, (png_structrp png_ptr));
+#endif
+
+#if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
+/* Invert monochrome files */
+PNG_EXPORT(46, void, png_set_invert_mono, (png_structrp png_ptr));
+#endif
+
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
+/* Handle alpha and tRNS by replacing with a background color. Prior to
+ * libpng-1.5.4 this API must not be called before the PNG file header has been
+ * read. Doing so will result in unexpected behavior and possible warnings or
+ * errors if the PNG file contains a bKGD chunk.
+ */
+PNG_FP_EXPORT(47, void, png_set_background, (png_structrp png_ptr,
+ png_const_color_16p background_color, int background_gamma_code,
+ int need_expand, double background_gamma))
+PNG_FIXED_EXPORT(215, void, png_set_background_fixed, (png_structrp png_ptr,
+ png_const_color_16p background_color, int background_gamma_code,
+ int need_expand, png_fixed_point background_gamma))
+#endif
+#ifdef PNG_READ_BACKGROUND_SUPPORTED
+# define PNG_BACKGROUND_GAMMA_UNKNOWN 0
+# define PNG_BACKGROUND_GAMMA_SCREEN 1
+# define PNG_BACKGROUND_GAMMA_FILE 2
+# define PNG_BACKGROUND_GAMMA_UNIQUE 3
+#endif
+
+#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
+/* Scale a 16-bit depth file down to 8-bit, accurately. */
+PNG_EXPORT(229, void, png_set_scale_16, (png_structrp png_ptr));
+#endif
+
+#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
+#define PNG_READ_16_TO_8 SUPPORTED /* Name prior to 1.5.4 */
+/* Strip the second byte of information from a 16-bit depth file. */
+PNG_EXPORT(48, void, png_set_strip_16, (png_structrp png_ptr));
+#endif
+
+#ifdef PNG_READ_QUANTIZE_SUPPORTED
+/* Turn on quantizing, and reduce the palette to the number of colors
+ * available.
+ */
+PNG_EXPORT(49, void, png_set_quantize, (png_structrp png_ptr,
+ png_colorp palette, int num_palette, int maximum_colors,
+ png_const_uint_16p histogram, int full_quantize));
+#endif
+
+#ifdef PNG_READ_GAMMA_SUPPORTED
+/* The threshold on gamma processing is configurable but hard-wired into the
+ * library. The following is the floating point variant.
+ */
+#define PNG_GAMMA_THRESHOLD (PNG_GAMMA_THRESHOLD_FIXED*.00001)
+
+/* Handle gamma correction. Screen_gamma=(display_exponent).
+ * NOTE: this API simply sets the screen and file gamma values. It will
+ * therefore override the value for gamma in a PNG file if it is called after
+ * the file header has been read - use with care - call before reading the PNG
+ * file for best results!
+ *
+ * These routines accept the same gamma values as png_set_alpha_mode (described
+ * above). The PNG_GAMMA_ defines and PNG_DEFAULT_sRGB can be passed to either
+ * API (floating point or fixed.) Notice, however, that the 'file_gamma' value
+ * is the inverse of a 'screen gamma' value.
+ */
+PNG_FP_EXPORT(50, void, png_set_gamma, (png_structrp png_ptr,
+ double screen_gamma, double override_file_gamma))
+PNG_FIXED_EXPORT(208, void, png_set_gamma_fixed, (png_structrp png_ptr,
+ png_fixed_point screen_gamma, png_fixed_point override_file_gamma))
+#endif
+
+#ifdef PNG_WRITE_FLUSH_SUPPORTED
+/* Set how many lines between output flushes - 0 for no flushing */
+PNG_EXPORT(51, void, png_set_flush, (png_structrp png_ptr, int nrows));
+/* Flush the current PNG output buffer */
+PNG_EXPORT(52, void, png_write_flush, (png_structrp png_ptr));
+#endif
+
+/* Optional update palette with requested transformations */
+PNG_EXPORT(53, void, png_start_read_image, (png_structrp png_ptr));
+
+/* Optional call to update the users info structure */
+PNG_EXPORT(54, void, png_read_update_info, (png_structrp png_ptr,
+ png_inforp info_ptr));
+
+#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
+/* Read one or more rows of image data. */
+PNG_EXPORT(55, void, png_read_rows, (png_structrp png_ptr, png_bytepp row,
+ png_bytepp display_row, png_uint_32 num_rows));
+#endif
+
+#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
+/* Read a row of data. */
+PNG_EXPORT(56, void, png_read_row, (png_structrp png_ptr, png_bytep row,
+ png_bytep display_row));
+#endif
+
+#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
+/* Read the whole image into memory at once. */
+PNG_EXPORT(57, void, png_read_image, (png_structrp png_ptr, png_bytepp image));
+#endif
+
+/* Write a row of image data */
+PNG_EXPORT(58, void, png_write_row, (png_structrp png_ptr,
+ png_const_bytep row));
+
+/* Write a few rows of image data: (*row) is not written; however, the type
+ * is declared as writeable to maintain compatibility with previous versions
+ * of libpng and to allow the 'display_row' array from read_rows to be passed
+ * unchanged to write_rows.
+ */
+PNG_EXPORT(59, void, png_write_rows, (png_structrp png_ptr, png_bytepp row,
+ png_uint_32 num_rows));
+
+/* Write the image data */
+PNG_EXPORT(60, void, png_write_image, (png_structrp png_ptr, png_bytepp image));
+
+/* Write the end of the PNG file. */
+PNG_EXPORT(61, void, png_write_end, (png_structrp png_ptr,
+ png_inforp info_ptr));
+
+#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
+/* Read the end of the PNG file. */
+PNG_EXPORT(62, void, png_read_end, (png_structrp png_ptr, png_inforp info_ptr));
+#endif
+
+/* Free any memory associated with the png_info_struct */
+PNG_EXPORT(63, void, png_destroy_info_struct, (png_const_structrp png_ptr,
+ png_infopp info_ptr_ptr));
+
+/* Free any memory associated with the png_struct and the png_info_structs */
+PNG_EXPORT(64, void, png_destroy_read_struct, (png_structpp png_ptr_ptr,
+ png_infopp info_ptr_ptr, png_infopp end_info_ptr_ptr));
+
+/* Free any memory associated with the png_struct and the png_info_structs */
+PNG_EXPORT(65, void, png_destroy_write_struct, (png_structpp png_ptr_ptr,
+ png_infopp info_ptr_ptr));
+
+/* Set the libpng method of handling chunk CRC errors */
+PNG_EXPORT(66, void, png_set_crc_action, (png_structrp png_ptr, int crit_action,
+ int ancil_action));
+
+/* Values for png_set_crc_action() say how to handle CRC errors in
+ * ancillary and critical chunks, and whether to use the data contained
+ * therein. Note that it is impossible to "discard" data in a critical
+ * chunk. For versions prior to 0.90, the action was always error/quit,
+ * whereas in version 0.90 and later, the action for CRC errors in ancillary
+ * chunks is warn/discard. These values should NOT be changed.
+ *
+ * value action:critical action:ancillary
+ */
+#define PNG_CRC_DEFAULT 0 /* error/quit warn/discard data */
+#define PNG_CRC_ERROR_QUIT 1 /* error/quit error/quit */
+#define PNG_CRC_WARN_DISCARD 2 /* (INVALID) warn/discard data */
+#define PNG_CRC_WARN_USE 3 /* warn/use data warn/use data */
+#define PNG_CRC_QUIET_USE 4 /* quiet/use data quiet/use data */
+#define PNG_CRC_NO_CHANGE 5 /* use current value use current value */
+
+#ifdef PNG_WRITE_SUPPORTED
+/* These functions give the user control over the scan-line filtering in
+ * libpng and the compression methods used by zlib. These functions are
+ * mainly useful for testing, as the defaults should work with most users.
+ * Those users who are tight on memory or want faster performance at the
+ * expense of compression can modify them. See the compression library
+ * header file (zlib.h) for an explination of the compression functions.
+ */
+
+/* Set the filtering method(s) used by libpng. Currently, the only valid
+ * value for "method" is 0.
+ */
+PNG_EXPORT(67, void, png_set_filter, (png_structrp png_ptr, int method,
+ int filters));
+#endif /* WRITE */
+
+/* Flags for png_set_filter() to say which filters to use. The flags
+ * are chosen so that they don't conflict with real filter types
+ * below, in case they are supplied instead of the #defined constants.
+ * These values should NOT be changed.
+ */
+#define PNG_NO_FILTERS 0x00
+#define PNG_FILTER_NONE 0x08
+#define PNG_FILTER_SUB 0x10
+#define PNG_FILTER_UP 0x20
+#define PNG_FILTER_AVG 0x40
+#define PNG_FILTER_PAETH 0x80
+#define PNG_ALL_FILTERS (PNG_FILTER_NONE | PNG_FILTER_SUB | PNG_FILTER_UP | \
+ PNG_FILTER_AVG | PNG_FILTER_PAETH)
+
+/* Filter values (not flags) - used in pngwrite.c, pngwutil.c for now.
+ * These defines should NOT be changed.
+ */
+#define PNG_FILTER_VALUE_NONE 0
+#define PNG_FILTER_VALUE_SUB 1
+#define PNG_FILTER_VALUE_UP 2
+#define PNG_FILTER_VALUE_AVG 3
+#define PNG_FILTER_VALUE_PAETH 4
+#define PNG_FILTER_VALUE_LAST 5
+
+#ifdef PNG_WRITE_SUPPORTED
+#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* DEPRECATED */
+PNG_FP_EXPORT(68, void, png_set_filter_heuristics, (png_structrp png_ptr,
+ int heuristic_method, int num_weights, png_const_doublep filter_weights,
+ png_const_doublep filter_costs))
+PNG_FIXED_EXPORT(209, void, png_set_filter_heuristics_fixed,
+ (png_structrp png_ptr, int heuristic_method, int num_weights,
+ png_const_fixed_point_p filter_weights,
+ png_const_fixed_point_p filter_costs))
+#endif /* WRITE_WEIGHTED_FILTER */
+
+/* The following are no longer used and will be removed from libpng-1.7: */
+#define PNG_FILTER_HEURISTIC_DEFAULT 0 /* Currently "UNWEIGHTED" */
+#define PNG_FILTER_HEURISTIC_UNWEIGHTED 1 /* Used by libpng < 0.95 */
+#define PNG_FILTER_HEURISTIC_WEIGHTED 2 /* Experimental feature */
+#define PNG_FILTER_HEURISTIC_LAST 3 /* Not a valid value */
+
+/* Set the library compression level. Currently, valid values range from
+ * 0 - 9, corresponding directly to the zlib compression levels 0 - 9
+ * (0 - no compression, 9 - "maximal" compression). Note that tests have
+ * shown that zlib compression levels 3-6 usually perform as well as level 9
+ * for PNG images, and do considerably fewer caclulations. In the future,
+ * these values may not correspond directly to the zlib compression levels.
+ */
+#ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
+PNG_EXPORT(69, void, png_set_compression_level, (png_structrp png_ptr,
+ int level));
+
+PNG_EXPORT(70, void, png_set_compression_mem_level, (png_structrp png_ptr,
+ int mem_level));
+
+PNG_EXPORT(71, void, png_set_compression_strategy, (png_structrp png_ptr,
+ int strategy));
+
+/* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
+ * smaller value of window_bits if it can do so safely.
+ */
+PNG_EXPORT(72, void, png_set_compression_window_bits, (png_structrp png_ptr,
+ int window_bits));
+
+PNG_EXPORT(73, void, png_set_compression_method, (png_structrp png_ptr,
+ int method));
+#endif /* WRITE_CUSTOMIZE_COMPRESSION */
+
+#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
+/* Also set zlib parameters for compressing non-IDAT chunks */
+PNG_EXPORT(222, void, png_set_text_compression_level, (png_structrp png_ptr,
+ int level));
+
+PNG_EXPORT(223, void, png_set_text_compression_mem_level, (png_structrp png_ptr,
+ int mem_level));
+
+PNG_EXPORT(224, void, png_set_text_compression_strategy, (png_structrp png_ptr,
+ int strategy));
+
+/* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
+ * smaller value of window_bits if it can do so safely.
+ */
+PNG_EXPORT(225, void, png_set_text_compression_window_bits,
+ (png_structrp png_ptr, int window_bits));
+
+PNG_EXPORT(226, void, png_set_text_compression_method, (png_structrp png_ptr,
+ int method));
+#endif /* WRITE_CUSTOMIZE_ZTXT_COMPRESSION */
+#endif /* WRITE */
+
+/* These next functions are called for input/output, memory, and error
+ * handling. They are in the file pngrio.c, pngwio.c, and pngerror.c,
+ * and call standard C I/O routines such as fread(), fwrite(), and
+ * fprintf(). These functions can be made to use other I/O routines
+ * at run time for those applications that need to handle I/O in a
+ * different manner by calling png_set_???_fn(). See libpng-manual.txt for
+ * more information.
+ */
+
+#ifdef PNG_STDIO_SUPPORTED
+/* Initialize the input/output for the PNG file to the default functions. */
+PNG_EXPORT(74, void, png_init_io, (png_structrp png_ptr, png_FILE_p fp));
+#endif
+
+/* Replace the (error and abort), and warning functions with user
+ * supplied functions. If no messages are to be printed you must still
+ * write and use replacement functions. The replacement error_fn should
+ * still do a longjmp to the last setjmp location if you are using this
+ * method of error handling. If error_fn or warning_fn is NULL, the
+ * default function will be used.
+ */
+
+PNG_EXPORT(75, void, png_set_error_fn, (png_structrp png_ptr,
+ png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warning_fn));
+
+/* Return the user pointer associated with the error functions */
+PNG_EXPORT(76, png_voidp, png_get_error_ptr, (png_const_structrp png_ptr));
+
+/* Replace the default data output functions with a user supplied one(s).
+ * If buffered output is not used, then output_flush_fn can be set to NULL.
+ * If PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile time
+ * output_flush_fn will be ignored (and thus can be NULL).
+ * It is probably a mistake to use NULL for output_flush_fn if
+ * write_data_fn is not also NULL unless you have built libpng with
+ * PNG_WRITE_FLUSH_SUPPORTED undefined, because in this case libpng's
+ * default flush function, which uses the standard *FILE structure, will
+ * be used.
+ */
+PNG_EXPORT(77, void, png_set_write_fn, (png_structrp png_ptr, png_voidp io_ptr,
+ png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn));
+
+/* Replace the default data input function with a user supplied one. */
+PNG_EXPORT(78, void, png_set_read_fn, (png_structrp png_ptr, png_voidp io_ptr,
+ png_rw_ptr read_data_fn));
+
+/* Return the user pointer associated with the I/O functions */
+PNG_EXPORT(79, png_voidp, png_get_io_ptr, (png_const_structrp png_ptr));
+
+PNG_EXPORT(80, void, png_set_read_status_fn, (png_structrp png_ptr,
+ png_read_status_ptr read_row_fn));
+
+PNG_EXPORT(81, void, png_set_write_status_fn, (png_structrp png_ptr,
+ png_write_status_ptr write_row_fn));
+
+#ifdef PNG_USER_MEM_SUPPORTED
+/* Replace the default memory allocation functions with user supplied one(s). */
+PNG_EXPORT(82, void, png_set_mem_fn, (png_structrp png_ptr, png_voidp mem_ptr,
+ png_malloc_ptr malloc_fn, png_free_ptr free_fn));
+/* Return the user pointer associated with the memory functions */
+PNG_EXPORT(83, png_voidp, png_get_mem_ptr, (png_const_structrp png_ptr));
+#endif
+
+#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
+PNG_EXPORT(84, void, png_set_read_user_transform_fn, (png_structrp png_ptr,
+ png_user_transform_ptr read_user_transform_fn));
+#endif
+
+#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
+PNG_EXPORT(85, void, png_set_write_user_transform_fn, (png_structrp png_ptr,
+ png_user_transform_ptr write_user_transform_fn));
+#endif
+
+#ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
+PNG_EXPORT(86, void, png_set_user_transform_info, (png_structrp png_ptr,
+ png_voidp user_transform_ptr, int user_transform_depth,
+ int user_transform_channels));
+/* Return the user pointer associated with the user transform functions */
+PNG_EXPORT(87, png_voidp, png_get_user_transform_ptr,
+ (png_const_structrp png_ptr));
+#endif
+
+#ifdef PNG_USER_TRANSFORM_INFO_SUPPORTED
+/* Return information about the row currently being processed. Note that these
+ * APIs do not fail but will return unexpected results if called outside a user
+ * transform callback. Also note that when transforming an interlaced image the
+ * row number is the row number within the sub-image of the interlace pass, so
+ * the value will increase to the height of the sub-image (not the full image)
+ * then reset to 0 for the next pass.
+ *
+ * Use PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
+ * find the output pixel (x,y) given an interlaced sub-image pixel
+ * (row,col,pass). (See below for these macros.)
+ */
+PNG_EXPORT(217, png_uint_32, png_get_current_row_number, (png_const_structrp));
+PNG_EXPORT(218, png_byte, png_get_current_pass_number, (png_const_structrp));
+#endif
+
+#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
+/* This callback is called only for *unknown* chunks. If
+ * PNG_HANDLE_AS_UNKNOWN_SUPPORTED is set then it is possible to set known
+ * chunks to be treated as unknown, however in this case the callback must do
+ * any processing required by the chunk (e.g. by calling the appropriate
+ * png_set_ APIs.)
+ *
+ * There is no write support - on write, by default, all the chunks in the
+ * 'unknown' list are written in the specified position.
+ *
+ * The integer return from the callback function is interpreted thus:
+ *
+ * negative: An error occurred; png_chunk_error will be called.
+ * zero: The chunk was not handled, the chunk will be saved. A critical
+ * chunk will cause an error at this point unless it is to be saved.
+ * positive: The chunk was handled, libpng will ignore/discard it.
+ *
+ * See "INTERACTION WTIH USER CHUNK CALLBACKS" below for important notes about
+ * how this behavior will change in libpng 1.7
+ */
+PNG_EXPORT(88, void, png_set_read_user_chunk_fn, (png_structrp png_ptr,
+ png_voidp user_chunk_ptr, png_user_chunk_ptr read_user_chunk_fn));
+#endif
+
+#ifdef PNG_USER_CHUNKS_SUPPORTED
+PNG_EXPORT(89, png_voidp, png_get_user_chunk_ptr, (png_const_structrp png_ptr));
+#endif
+
+#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
+/* Sets the function callbacks for the push reader, and a pointer to a
+ * user-defined structure available to the callback functions.
+ */
+PNG_EXPORT(90, void, png_set_progressive_read_fn, (png_structrp png_ptr,
+ png_voidp progressive_ptr, png_progressive_info_ptr info_fn,
+ png_progressive_row_ptr row_fn, png_progressive_end_ptr end_fn));
+
+/* Returns the user pointer associated with the push read functions */
+PNG_EXPORT(91, png_voidp, png_get_progressive_ptr,
+ (png_const_structrp png_ptr));
+
+/* Function to be called when data becomes available */
+PNG_EXPORT(92, void, png_process_data, (png_structrp png_ptr,
+ png_inforp info_ptr, png_bytep buffer, png_size_t buffer_size));
+
+/* A function which may be called *only* within png_process_data to stop the
+ * processing of any more data. The function returns the number of bytes
+ * remaining, excluding any that libpng has cached internally. A subsequent
+ * call to png_process_data must supply these bytes again. If the argument
+ * 'save' is set to true the routine will first save all the pending data and
+ * will always return 0.
+ */
+PNG_EXPORT(219, png_size_t, png_process_data_pause, (png_structrp, int save));
+
+/* A function which may be called *only* outside (after) a call to
+ * png_process_data. It returns the number of bytes of data to skip in the
+ * input. Normally it will return 0, but if it returns a non-zero value the
+ * application must skip than number of bytes of input data and pass the
+ * following data to the next call to png_process_data.
+ */
+PNG_EXPORT(220, png_uint_32, png_process_data_skip, (png_structrp));
+
+/* Function that combines rows. 'new_row' is a flag that should come from
+ * the callback and be non-NULL if anything needs to be done; the library
+ * stores its own version of the new data internally and ignores the passed
+ * in value.
+ */
+PNG_EXPORT(93, void, png_progressive_combine_row, (png_const_structrp png_ptr,
+ png_bytep old_row, png_const_bytep new_row));
+#endif /* PROGRESSIVE_READ */
+
+PNG_EXPORTA(94, png_voidp, png_malloc, (png_const_structrp png_ptr,
+ png_alloc_size_t size), PNG_ALLOCATED);
+/* Added at libpng version 1.4.0 */
+PNG_EXPORTA(95, png_voidp, png_calloc, (png_const_structrp png_ptr,
+ png_alloc_size_t size), PNG_ALLOCATED);
+
+/* Added at libpng version 1.2.4 */
+PNG_EXPORTA(96, png_voidp, png_malloc_warn, (png_const_structrp png_ptr,
+ png_alloc_size_t size), PNG_ALLOCATED);
+
+/* Frees a pointer allocated by png_malloc() */
+PNG_EXPORT(97, void, png_free, (png_const_structrp png_ptr, png_voidp ptr));
+
+/* Free data that was allocated internally */
+PNG_EXPORT(98, void, png_free_data, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_uint_32 free_me, int num));
+
+/* Reassign responsibility for freeing existing data, whether allocated
+ * by libpng or by the application; this works on the png_info structure passed
+ * in, it does not change the state for other png_info structures.
+ *
+ * It is unlikely that this function works correctly as of 1.6.0 and using it
+ * may result either in memory leaks or double free of allocated data.
+ */
+PNG_EXPORT(99, void, png_data_freer, (png_const_structrp png_ptr,
+ png_inforp info_ptr, int freer, png_uint_32 mask));
+
+#ifdef PNG_INDEX_SUPPORTED
+/* Build image index for partial image decoding. */
+PNG_EXPORT(300, void, png_build_index, (png_structp png_ptr));
+PNG_EXPORT(301, void, png_configure_decoder,
+ (png_structp png_ptr, int *row_offset, int pass));
+/* Set the data seek function with a user supplied one.
+ * REQUIRED by partial image decode.
+ */
+PNG_EXPORT(302, void, png_set_seek_fn, (png_structp png_ptr,
+ png_seek_ptr seek_data_fn));
+/* Update the decoder status to the given pass */
+PNG_EXPORT(303, void, png_set_interlaced_pass, (png_structp png_ptr, int pass));
+#endif
+
+/* Assignments for png_data_freer */
+#define PNG_DESTROY_WILL_FREE_DATA 1
+#define PNG_SET_WILL_FREE_DATA 1
+#define PNG_USER_WILL_FREE_DATA 2
+/* Flags for png_ptr->free_me and info_ptr->free_me */
+#define PNG_FREE_HIST 0x0008
+#define PNG_FREE_ICCP 0x0010
+#define PNG_FREE_SPLT 0x0020
+#define PNG_FREE_ROWS 0x0040
+#define PNG_FREE_PCAL 0x0080
+#define PNG_FREE_SCAL 0x0100
+#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
+# define PNG_FREE_UNKN 0x0200
+#endif
+/* PNG_FREE_LIST 0x0400 removed in 1.6.0 because it is ignored */
+#define PNG_FREE_PLTE 0x1000
+#define PNG_FREE_TRNS 0x2000
+#define PNG_FREE_TEXT 0x4000
+#define PNG_FREE_ALL 0x7fff
+#define PNG_FREE_MUL 0x4220 /* PNG_FREE_SPLT|PNG_FREE_TEXT|PNG_FREE_UNKN */
+
+#ifdef PNG_USER_MEM_SUPPORTED
+PNG_EXPORTA(100, png_voidp, png_malloc_default, (png_const_structrp png_ptr,
+ png_alloc_size_t size), PNG_ALLOCATED PNG_DEPRECATED);
+PNG_EXPORTA(101, void, png_free_default, (png_const_structrp png_ptr,
+ png_voidp ptr), PNG_DEPRECATED);
+#endif
+
+#ifdef PNG_ERROR_TEXT_SUPPORTED
+/* Fatal error in PNG image of libpng - can't continue */
+PNG_EXPORTA(102, void, png_error, (png_const_structrp png_ptr,
+ png_const_charp error_message), PNG_NORETURN);
+
+/* The same, but the chunk name is prepended to the error string. */
+PNG_EXPORTA(103, void, png_chunk_error, (png_const_structrp png_ptr,
+ png_const_charp error_message), PNG_NORETURN);
+
+#else
+/* Fatal error in PNG image of libpng - can't continue */
+PNG_EXPORTA(104, void, png_err, (png_const_structrp png_ptr), PNG_NORETURN);
+# define png_error(s1,s2) png_err(s1)
+# define png_chunk_error(s1,s2) png_err(s1)
+#endif
+
+#ifdef PNG_WARNINGS_SUPPORTED
+/* Non-fatal error in libpng. Can continue, but may have a problem. */
+PNG_EXPORT(105, void, png_warning, (png_const_structrp png_ptr,
+ png_const_charp warning_message));
+
+/* Non-fatal error in libpng, chunk name is prepended to message. */
+PNG_EXPORT(106, void, png_chunk_warning, (png_const_structrp png_ptr,
+ png_const_charp warning_message));
+#else
+# define png_warning(s1,s2) ((void)(s1))
+# define png_chunk_warning(s1,s2) ((void)(s1))
+#endif
+
+#ifdef PNG_BENIGN_ERRORS_SUPPORTED
+/* Benign error in libpng. Can continue, but may have a problem.
+ * User can choose whether to handle as a fatal error or as a warning. */
+PNG_EXPORT(107, void, png_benign_error, (png_const_structrp png_ptr,
+ png_const_charp warning_message));
+
+#ifdef PNG_READ_SUPPORTED
+/* Same, chunk name is prepended to message (only during read) */
+PNG_EXPORT(108, void, png_chunk_benign_error, (png_const_structrp png_ptr,
+ png_const_charp warning_message));
+#endif
+
+PNG_EXPORT(109, void, png_set_benign_errors,
+ (png_structrp png_ptr, int allowed));
+#else
+# ifdef PNG_ALLOW_BENIGN_ERRORS
+# define png_benign_error png_warning
+# define png_chunk_benign_error png_chunk_warning
+# else
+# define png_benign_error png_error
+# define png_chunk_benign_error png_chunk_error
+# endif
+#endif
+
+/* The png_set_<chunk> functions are for storing values in the png_info_struct.
+ * Similarly, the png_get_<chunk> calls are used to read values from the
+ * png_info_struct, either storing the parameters in the passed variables, or
+ * setting pointers into the png_info_struct where the data is stored. The
+ * png_get_<chunk> functions return a non-zero value if the data was available
+ * in info_ptr, or return zero and do not change any of the parameters if the
+ * data was not available.
+ *
+ * These functions should be used instead of directly accessing png_info
+ * to avoid problems with future changes in the size and internal layout of
+ * png_info_struct.
+ */
+/* Returns "flag" if chunk data is valid in info_ptr. */
+PNG_EXPORT(110, png_uint_32, png_get_valid, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr, png_uint_32 flag));
+
+/* Returns number of bytes needed to hold a transformed row. */
+PNG_EXPORT(111, png_size_t, png_get_rowbytes, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr));
+
+#ifdef PNG_INFO_IMAGE_SUPPORTED
+/* Returns row_pointers, which is an array of pointers to scanlines that was
+ * returned from png_read_png().
+ */
+PNG_EXPORT(112, png_bytepp, png_get_rows, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr));
+
+/* Set row_pointers, which is an array of pointers to scanlines for use
+ * by png_write_png().
+ */
+PNG_EXPORT(113, void, png_set_rows, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_bytepp row_pointers));
+#endif
+
+/* Returns number of color channels in image. */
+PNG_EXPORT(114, png_byte, png_get_channels, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr));
+
+#ifdef PNG_EASY_ACCESS_SUPPORTED
+/* Returns image width in pixels. */
+PNG_EXPORT(115, png_uint_32, png_get_image_width, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr));
+
+/* Returns image height in pixels. */
+PNG_EXPORT(116, png_uint_32, png_get_image_height, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr));
+
+/* Returns image bit_depth. */
+PNG_EXPORT(117, png_byte, png_get_bit_depth, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr));
+
+/* Returns image color_type. */
+PNG_EXPORT(118, png_byte, png_get_color_type, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr));
+
+/* Returns image filter_type. */
+PNG_EXPORT(119, png_byte, png_get_filter_type, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr));
+
+/* Returns image interlace_type. */
+PNG_EXPORT(120, png_byte, png_get_interlace_type, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr));
+
+/* Returns image compression_type. */
+PNG_EXPORT(121, png_byte, png_get_compression_type, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr));
+
+/* Returns image resolution in pixels per meter, from pHYs chunk data. */
+PNG_EXPORT(122, png_uint_32, png_get_pixels_per_meter,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr));
+PNG_EXPORT(123, png_uint_32, png_get_x_pixels_per_meter,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr));
+PNG_EXPORT(124, png_uint_32, png_get_y_pixels_per_meter,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr));
+
+/* Returns pixel aspect ratio, computed from pHYs chunk data. */
+PNG_FP_EXPORT(125, float, png_get_pixel_aspect_ratio,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr))
+PNG_FIXED_EXPORT(210, png_fixed_point, png_get_pixel_aspect_ratio_fixed,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr))
+
+/* Returns image x, y offset in pixels or microns, from oFFs chunk data. */
+PNG_EXPORT(126, png_int_32, png_get_x_offset_pixels,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr));
+PNG_EXPORT(127, png_int_32, png_get_y_offset_pixels,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr));
+PNG_EXPORT(128, png_int_32, png_get_x_offset_microns,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr));
+PNG_EXPORT(129, png_int_32, png_get_y_offset_microns,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr));
+
+#endif /* EASY_ACCESS */
+
+#ifdef PNG_READ_SUPPORTED
+/* Returns pointer to signature string read from PNG header */
+PNG_EXPORT(130, png_const_bytep, png_get_signature, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr));
+#endif
+
+#ifdef PNG_bKGD_SUPPORTED
+PNG_EXPORT(131, png_uint_32, png_get_bKGD, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_color_16p *background));
+#endif
+
+#ifdef PNG_bKGD_SUPPORTED
+PNG_EXPORT(132, void, png_set_bKGD, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_const_color_16p background));
+#endif
+
+#ifdef PNG_cHRM_SUPPORTED
+PNG_FP_EXPORT(133, png_uint_32, png_get_cHRM, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr, double *white_x, double *white_y, double *red_x,
+ double *red_y, double *green_x, double *green_y, double *blue_x,
+ double *blue_y))
+PNG_FP_EXPORT(230, png_uint_32, png_get_cHRM_XYZ, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr, double *red_X, double *red_Y, double *red_Z,
+ double *green_X, double *green_Y, double *green_Z, double *blue_X,
+ double *blue_Y, double *blue_Z))
+PNG_FIXED_EXPORT(134, png_uint_32, png_get_cHRM_fixed,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr,
+ png_fixed_point *int_white_x, png_fixed_point *int_white_y,
+ png_fixed_point *int_red_x, png_fixed_point *int_red_y,
+ png_fixed_point *int_green_x, png_fixed_point *int_green_y,
+ png_fixed_point *int_blue_x, png_fixed_point *int_blue_y))
+PNG_FIXED_EXPORT(231, png_uint_32, png_get_cHRM_XYZ_fixed,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr,
+ png_fixed_point *int_red_X, png_fixed_point *int_red_Y,
+ png_fixed_point *int_red_Z, png_fixed_point *int_green_X,
+ png_fixed_point *int_green_Y, png_fixed_point *int_green_Z,
+ png_fixed_point *int_blue_X, png_fixed_point *int_blue_Y,
+ png_fixed_point *int_blue_Z))
+#endif
+
+#ifdef PNG_cHRM_SUPPORTED
+PNG_FP_EXPORT(135, void, png_set_cHRM, (png_const_structrp png_ptr,
+ png_inforp info_ptr,
+ double white_x, double white_y, double red_x, double red_y, double green_x,
+ double green_y, double blue_x, double blue_y))
+PNG_FP_EXPORT(232, void, png_set_cHRM_XYZ, (png_const_structrp png_ptr,
+ png_inforp info_ptr, double red_X, double red_Y, double red_Z,
+ double green_X, double green_Y, double green_Z, double blue_X,
+ double blue_Y, double blue_Z))
+PNG_FIXED_EXPORT(136, void, png_set_cHRM_fixed, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_fixed_point int_white_x,
+ png_fixed_point int_white_y, png_fixed_point int_red_x,
+ png_fixed_point int_red_y, png_fixed_point int_green_x,
+ png_fixed_point int_green_y, png_fixed_point int_blue_x,
+ png_fixed_point int_blue_y))
+PNG_FIXED_EXPORT(233, void, png_set_cHRM_XYZ_fixed, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_fixed_point int_red_X, png_fixed_point int_red_Y,
+ png_fixed_point int_red_Z, png_fixed_point int_green_X,
+ png_fixed_point int_green_Y, png_fixed_point int_green_Z,
+ png_fixed_point int_blue_X, png_fixed_point int_blue_Y,
+ png_fixed_point int_blue_Z))
+#endif
+
+#ifdef PNG_gAMA_SUPPORTED
+PNG_FP_EXPORT(137, png_uint_32, png_get_gAMA, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr, double *file_gamma))
+PNG_FIXED_EXPORT(138, png_uint_32, png_get_gAMA_fixed,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr,
+ png_fixed_point *int_file_gamma))
+#endif
+
+#ifdef PNG_gAMA_SUPPORTED
+PNG_FP_EXPORT(139, void, png_set_gAMA, (png_const_structrp png_ptr,
+ png_inforp info_ptr, double file_gamma))
+PNG_FIXED_EXPORT(140, void, png_set_gAMA_fixed, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_fixed_point int_file_gamma))
+#endif
+
+#ifdef PNG_hIST_SUPPORTED
+PNG_EXPORT(141, png_uint_32, png_get_hIST, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_uint_16p *hist));
+#endif
+
+#ifdef PNG_hIST_SUPPORTED
+PNG_EXPORT(142, void, png_set_hIST, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_const_uint_16p hist));
+#endif
+
+PNG_EXPORT(143, png_uint_32, png_get_IHDR, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr, png_uint_32 *width, png_uint_32 *height,
+ int *bit_depth, int *color_type, int *interlace_method,
+ int *compression_method, int *filter_method));
+
+PNG_EXPORT(144, void, png_set_IHDR, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_uint_32 width, png_uint_32 height, int bit_depth,
+ int color_type, int interlace_method, int compression_method,
+ int filter_method));
+
+#ifdef PNG_oFFs_SUPPORTED
+PNG_EXPORT(145, png_uint_32, png_get_oFFs, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr, png_int_32 *offset_x, png_int_32 *offset_y,
+ int *unit_type));
+#endif
+
+#ifdef PNG_oFFs_SUPPORTED
+PNG_EXPORT(146, void, png_set_oFFs, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_int_32 offset_x, png_int_32 offset_y,
+ int unit_type));
+#endif
+
+#ifdef PNG_pCAL_SUPPORTED
+PNG_EXPORT(147, png_uint_32, png_get_pCAL, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_charp *purpose, png_int_32 *X0,
+ png_int_32 *X1, int *type, int *nparams, png_charp *units,
+ png_charpp *params));
+#endif
+
+#ifdef PNG_pCAL_SUPPORTED
+PNG_EXPORT(148, void, png_set_pCAL, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_const_charp purpose, png_int_32 X0, png_int_32 X1,
+ int type, int nparams, png_const_charp units, png_charpp params));
+#endif
+
+#ifdef PNG_pHYs_SUPPORTED
+PNG_EXPORT(149, png_uint_32, png_get_pHYs, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr, png_uint_32 *res_x, png_uint_32 *res_y,
+ int *unit_type));
+#endif
+
+#ifdef PNG_pHYs_SUPPORTED
+PNG_EXPORT(150, void, png_set_pHYs, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_uint_32 res_x, png_uint_32 res_y, int unit_type));
+#endif
+
+PNG_EXPORT(151, png_uint_32, png_get_PLTE, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_colorp *palette, int *num_palette));
+
+PNG_EXPORT(152, void, png_set_PLTE, (png_structrp png_ptr,
+ png_inforp info_ptr, png_const_colorp palette, int num_palette));
+
+#ifdef PNG_sBIT_SUPPORTED
+PNG_EXPORT(153, png_uint_32, png_get_sBIT, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_color_8p *sig_bit));
+#endif
+
+#ifdef PNG_sBIT_SUPPORTED
+PNG_EXPORT(154, void, png_set_sBIT, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_const_color_8p sig_bit));
+#endif
+
+#ifdef PNG_sRGB_SUPPORTED
+PNG_EXPORT(155, png_uint_32, png_get_sRGB, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr, int *file_srgb_intent));
+#endif
+
+#ifdef PNG_sRGB_SUPPORTED
+PNG_EXPORT(156, void, png_set_sRGB, (png_const_structrp png_ptr,
+ png_inforp info_ptr, int srgb_intent));
+PNG_EXPORT(157, void, png_set_sRGB_gAMA_and_cHRM, (png_const_structrp png_ptr,
+ png_inforp info_ptr, int srgb_intent));
+#endif
+
+#ifdef PNG_iCCP_SUPPORTED
+PNG_EXPORT(158, png_uint_32, png_get_iCCP, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_charpp name, int *compression_type,
+ png_bytepp profile, png_uint_32 *proflen));
+#endif
+
+#ifdef PNG_iCCP_SUPPORTED
+PNG_EXPORT(159, void, png_set_iCCP, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_const_charp name, int compression_type,
+ png_const_bytep profile, png_uint_32 proflen));
+#endif
+
+#ifdef PNG_sPLT_SUPPORTED
+PNG_EXPORT(160, int, png_get_sPLT, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_sPLT_tpp entries));
+#endif
+
+#ifdef PNG_sPLT_SUPPORTED
+PNG_EXPORT(161, void, png_set_sPLT, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_const_sPLT_tp entries, int nentries));
+#endif
+
+#ifdef PNG_TEXT_SUPPORTED
+/* png_get_text also returns the number of text chunks in *num_text */
+PNG_EXPORT(162, int, png_get_text, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_textp *text_ptr, int *num_text));
+#endif
+
+/* Note while png_set_text() will accept a structure whose text,
+ * language, and translated keywords are NULL pointers, the structure
+ * returned by png_get_text will always contain regular
+ * zero-terminated C strings. They might be empty strings but
+ * they will never be NULL pointers.
+ */
+
+#ifdef PNG_TEXT_SUPPORTED
+PNG_EXPORT(163, void, png_set_text, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_const_textp text_ptr, int num_text));
+#endif
+
+#ifdef PNG_tIME_SUPPORTED
+PNG_EXPORT(164, png_uint_32, png_get_tIME, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_timep *mod_time));
+#endif
+
+#ifdef PNG_tIME_SUPPORTED
+PNG_EXPORT(165, void, png_set_tIME, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_const_timep mod_time));
+#endif
+
+#ifdef PNG_tRNS_SUPPORTED
+PNG_EXPORT(166, png_uint_32, png_get_tRNS, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_bytep *trans_alpha, int *num_trans,
+ png_color_16p *trans_color));
+#endif
+
+#ifdef PNG_tRNS_SUPPORTED
+PNG_EXPORT(167, void, png_set_tRNS, (png_structrp png_ptr,
+ png_inforp info_ptr, png_const_bytep trans_alpha, int num_trans,
+ png_const_color_16p trans_color));
+#endif
+
+#ifdef PNG_sCAL_SUPPORTED
+PNG_FP_EXPORT(168, png_uint_32, png_get_sCAL, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr, int *unit, double *width, double *height))
+#if defined(PNG_FLOATING_ARITHMETIC_SUPPORTED) || \
+ defined(PNG_FLOATING_POINT_SUPPORTED)
+/* NOTE: this API is currently implemented using floating point arithmetic,
+ * consequently it can only be used on systems with floating point support.
+ * In any case the range of values supported by png_fixed_point is small and it
+ * is highly recommended that png_get_sCAL_s be used instead.
+ */
+PNG_FIXED_EXPORT(214, png_uint_32, png_get_sCAL_fixed,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr, int *unit,
+ png_fixed_point *width, png_fixed_point *height))
+#endif
+PNG_EXPORT(169, png_uint_32, png_get_sCAL_s,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr, int *unit,
+ png_charpp swidth, png_charpp sheight));
+
+PNG_FP_EXPORT(170, void, png_set_sCAL, (png_const_structrp png_ptr,
+ png_inforp info_ptr, int unit, double width, double height))
+PNG_FIXED_EXPORT(213, void, png_set_sCAL_fixed, (png_const_structrp png_ptr,
+ png_inforp info_ptr, int unit, png_fixed_point width,
+ png_fixed_point height))
+PNG_EXPORT(171, void, png_set_sCAL_s, (png_const_structrp png_ptr,
+ png_inforp info_ptr, int unit,
+ png_const_charp swidth, png_const_charp sheight));
+#endif /* sCAL */
+
+#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
+/* Provide the default handling for all unknown chunks or, optionally, for
+ * specific unknown chunks.
+ *
+ * NOTE: prior to 1.6.0 the handling specified for particular chunks on read was
+ * ignored and the default was used, the per-chunk setting only had an effect on
+ * write. If you wish to have chunk-specific handling on read in code that must
+ * work on earlier versions you must use a user chunk callback to specify the
+ * desired handling (keep or discard.)
+ *
+ * The 'keep' parameter is a PNG_HANDLE_CHUNK_ value as listed below. The
+ * parameter is interpreted as follows:
+ *
+ * READ:
+ * PNG_HANDLE_CHUNK_AS_DEFAULT:
+ * Known chunks: do normal libpng processing, do not keep the chunk (but
+ * see the comments below about PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
+ * Unknown chunks: for a specific chunk use the global default, when used
+ * as the default discard the chunk data.
+ * PNG_HANDLE_CHUNK_NEVER:
+ * Discard the chunk data.
+ * PNG_HANDLE_CHUNK_IF_SAFE:
+ * Keep the chunk data if the chunk is not critical else raise a chunk
+ * error.
+ * PNG_HANDLE_CHUNK_ALWAYS:
+ * Keep the chunk data.
+ *
+ * If the chunk data is saved it can be retrieved using png_get_unknown_chunks,
+ * below. Notice that specifying "AS_DEFAULT" as a global default is equivalent
+ * to specifying "NEVER", however when "AS_DEFAULT" is used for specific chunks
+ * it simply resets the behavior to the libpng default.
+ *
+ * INTERACTION WTIH USER CHUNK CALLBACKS:
+ * The per-chunk handling is always used when there is a png_user_chunk_ptr
+ * callback and the callback returns 0; the chunk is then always stored *unless*
+ * it is critical and the per-chunk setting is other than ALWAYS. Notice that
+ * the global default is *not* used in this case. (In effect the per-chunk
+ * value is incremented to at least IF_SAFE.)
+ *
+ * IMPORTANT NOTE: this behavior will change in libpng 1.7 - the global and
+ * per-chunk defaults will be honored. If you want to preserve the current
+ * behavior when your callback returns 0 you must set PNG_HANDLE_CHUNK_IF_SAFE
+ * as the default - if you don't do this libpng 1.6 will issue a warning.
+ *
+ * If you want unhandled unknown chunks to be discarded in libpng 1.6 and
+ * earlier simply return '1' (handled).
+ *
+ * PNG_HANDLE_AS_UNKNOWN_SUPPORTED:
+ * If this is *not* set known chunks will always be handled by libpng and
+ * will never be stored in the unknown chunk list. Known chunks listed to
+ * png_set_keep_unknown_chunks will have no effect. If it is set then known
+ * chunks listed with a keep other than AS_DEFAULT will *never* be processed
+ * by libpng, in addition critical chunks must either be processed by the
+ * callback or saved.
+ *
+ * The IHDR and IEND chunks must not be listed. Because this turns off the
+ * default handling for chunks that would otherwise be recognized the
+ * behavior of libpng transformations may well become incorrect!
+ *
+ * WRITE:
+ * When writing chunks the options only apply to the chunks specified by
+ * png_set_unknown_chunks (below), libpng will *always* write known chunks
+ * required by png_set_ calls and will always write the core critical chunks
+ * (as required for PLTE).
+ *
+ * Each chunk in the png_set_unknown_chunks list is looked up in the
+ * png_set_keep_unknown_chunks list to find the keep setting, this is then
+ * interpreted as follows:
+ *
+ * PNG_HANDLE_CHUNK_AS_DEFAULT:
+ * Write safe-to-copy chunks and write other chunks if the global
+ * default is set to _ALWAYS, otherwise don't write this chunk.
+ * PNG_HANDLE_CHUNK_NEVER:
+ * Do not write the chunk.
+ * PNG_HANDLE_CHUNK_IF_SAFE:
+ * Write the chunk if it is safe-to-copy, otherwise do not write it.
+ * PNG_HANDLE_CHUNK_ALWAYS:
+ * Write the chunk.
+ *
+ * Note that the default behavior is effectively the opposite of the read case -
+ * in read unknown chunks are not stored by default, in write they are written
+ * by default. Also the behavior of PNG_HANDLE_CHUNK_IF_SAFE is very different
+ * - on write the safe-to-copy bit is checked, on read the critical bit is
+ * checked and on read if the chunk is critical an error will be raised.
+ *
+ * num_chunks:
+ * ===========
+ * If num_chunks is positive, then the "keep" parameter specifies the manner
+ * for handling only those chunks appearing in the chunk_list array,
+ * otherwise the chunk list array is ignored.
+ *
+ * If num_chunks is 0 the "keep" parameter specifies the default behavior for
+ * unknown chunks, as described above.
+ *
+ * If num_chunks is negative, then the "keep" parameter specifies the manner
+ * for handling all unknown chunks plus all chunks recognized by libpng
+ * except for the IHDR, PLTE, tRNS, IDAT, and IEND chunks (which continue to
+ * be processed by libpng.
+ */
+PNG_EXPORT(172, void, png_set_keep_unknown_chunks, (png_structrp png_ptr,
+ int keep, png_const_bytep chunk_list, int num_chunks));
+
+/* The "keep" PNG_HANDLE_CHUNK_ parameter for the specified chunk is returned;
+ * the result is therefore true (non-zero) if special handling is required,
+ * false for the default handling.
+ */
+PNG_EXPORT(173, int, png_handle_as_unknown, (png_const_structrp png_ptr,
+ png_const_bytep chunk_name));
+#endif
+
+#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
+PNG_EXPORT(174, void, png_set_unknown_chunks, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_const_unknown_chunkp unknowns,
+ int num_unknowns));
+ /* NOTE: prior to 1.6.0 this routine set the 'location' field of the added
+ * unknowns to the location currently stored in the png_struct. This is
+ * invariably the wrong value on write. To fix this call the following API
+ * for each chunk in the list with the correct location. If you know your
+ * code won't be compiled on earlier versions you can rely on
+ * png_set_unknown_chunks(write-ptr, png_get_unknown_chunks(read-ptr)) doing
+ * the correct thing.
+ */
+
+PNG_EXPORT(175, void, png_set_unknown_chunk_location,
+ (png_const_structrp png_ptr, png_inforp info_ptr, int chunk, int location));
+
+PNG_EXPORT(176, int, png_get_unknown_chunks, (png_const_structrp png_ptr,
+ png_inforp info_ptr, png_unknown_chunkpp entries));
+#endif
+
+/* Png_free_data() will turn off the "valid" flag for anything it frees.
+ * If you need to turn it off for a chunk that your application has freed,
+ * you can use png_set_invalid(png_ptr, info_ptr, PNG_INFO_CHNK);
+ */
+PNG_EXPORT(177, void, png_set_invalid, (png_const_structrp png_ptr,
+ png_inforp info_ptr, int mask));
+
+#ifdef PNG_INFO_IMAGE_SUPPORTED
+/* The "params" pointer is currently not used and is for future expansion. */
+#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
+PNG_EXPORT(178, void, png_read_png, (png_structrp png_ptr, png_inforp info_ptr,
+ int transforms, png_voidp params));
+#endif
+#ifdef PNG_WRITE_SUPPORTED
+PNG_EXPORT(179, void, png_write_png, (png_structrp png_ptr, png_inforp info_ptr,
+ int transforms, png_voidp params));
+#endif
+#endif
+
+PNG_EXPORT(180, png_const_charp, png_get_copyright,
+ (png_const_structrp png_ptr));
+PNG_EXPORT(181, png_const_charp, png_get_header_ver,
+ (png_const_structrp png_ptr));
+PNG_EXPORT(182, png_const_charp, png_get_header_version,
+ (png_const_structrp png_ptr));
+PNG_EXPORT(183, png_const_charp, png_get_libpng_ver,
+ (png_const_structrp png_ptr));
+
+#ifdef PNG_MNG_FEATURES_SUPPORTED
+PNG_EXPORT(184, png_uint_32, png_permit_mng_features, (png_structrp png_ptr,
+ png_uint_32 mng_features_permitted));
+#endif
+
+/* For use in png_set_keep_unknown, added to version 1.2.6 */
+#define PNG_HANDLE_CHUNK_AS_DEFAULT 0
+#define PNG_HANDLE_CHUNK_NEVER 1
+#define PNG_HANDLE_CHUNK_IF_SAFE 2
+#define PNG_HANDLE_CHUNK_ALWAYS 3
+#define PNG_HANDLE_CHUNK_LAST 4
+
+/* Strip the prepended error numbers ("#nnn ") from error and warning
+ * messages before passing them to the error or warning handler.
+ */
+#ifdef PNG_ERROR_NUMBERS_SUPPORTED
+PNG_EXPORT(185, void, png_set_strip_error_numbers, (png_structrp png_ptr,
+ png_uint_32 strip_mode));
+#endif
+
+/* Added in libpng-1.2.6 */
+#ifdef PNG_SET_USER_LIMITS_SUPPORTED
+PNG_EXPORT(186, void, png_set_user_limits, (png_structrp png_ptr,
+ png_uint_32 user_width_max, png_uint_32 user_height_max));
+PNG_EXPORT(187, png_uint_32, png_get_user_width_max,
+ (png_const_structrp png_ptr));
+PNG_EXPORT(188, png_uint_32, png_get_user_height_max,
+ (png_const_structrp png_ptr));
+/* Added in libpng-1.4.0 */
+PNG_EXPORT(189, void, png_set_chunk_cache_max, (png_structrp png_ptr,
+ png_uint_32 user_chunk_cache_max));
+PNG_EXPORT(190, png_uint_32, png_get_chunk_cache_max,
+ (png_const_structrp png_ptr));
+/* Added in libpng-1.4.1 */
+PNG_EXPORT(191, void, png_set_chunk_malloc_max, (png_structrp png_ptr,
+ png_alloc_size_t user_chunk_cache_max));
+PNG_EXPORT(192, png_alloc_size_t, png_get_chunk_malloc_max,
+ (png_const_structrp png_ptr));
+#endif
+
+#if defined(PNG_INCH_CONVERSIONS_SUPPORTED)
+PNG_EXPORT(193, png_uint_32, png_get_pixels_per_inch,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr));
+
+PNG_EXPORT(194, png_uint_32, png_get_x_pixels_per_inch,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr));
+
+PNG_EXPORT(195, png_uint_32, png_get_y_pixels_per_inch,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr));
+
+PNG_FP_EXPORT(196, float, png_get_x_offset_inches,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr))
+#ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
+PNG_FIXED_EXPORT(211, png_fixed_point, png_get_x_offset_inches_fixed,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr))
+#endif
+
+PNG_FP_EXPORT(197, float, png_get_y_offset_inches, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr))
+#ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
+PNG_FIXED_EXPORT(212, png_fixed_point, png_get_y_offset_inches_fixed,
+ (png_const_structrp png_ptr, png_const_inforp info_ptr))
+#endif
+
+# ifdef PNG_pHYs_SUPPORTED
+PNG_EXPORT(198, png_uint_32, png_get_pHYs_dpi, (png_const_structrp png_ptr,
+ png_const_inforp info_ptr, png_uint_32 *res_x, png_uint_32 *res_y,
+ int *unit_type));
+# endif /* pHYs */
+#endif /* INCH_CONVERSIONS */
+
+/* Added in libpng-1.4.0 */
+#ifdef PNG_IO_STATE_SUPPORTED
+PNG_EXPORT(199, png_uint_32, png_get_io_state, (png_const_structrp png_ptr));
+
+/* Removed from libpng 1.6; use png_get_io_chunk_type. */
+PNG_REMOVED(200, png_const_bytep, png_get_io_chunk_name, (png_structrp png_ptr),
+ PNG_DEPRECATED)
+
+PNG_EXPORT(216, png_uint_32, png_get_io_chunk_type,
+ (png_const_structrp png_ptr));
+
+/* The flags returned by png_get_io_state() are the following: */
+# define PNG_IO_NONE 0x0000 /* no I/O at this moment */
+# define PNG_IO_READING 0x0001 /* currently reading */
+# define PNG_IO_WRITING 0x0002 /* currently writing */
+# define PNG_IO_SIGNATURE 0x0010 /* currently at the file signature */
+# define PNG_IO_CHUNK_HDR 0x0020 /* currently at the chunk header */
+# define PNG_IO_CHUNK_DATA 0x0040 /* currently at the chunk data */
+# define PNG_IO_CHUNK_CRC 0x0080 /* currently at the chunk crc */
+# define PNG_IO_MASK_OP 0x000f /* current operation: reading/writing */
+# define PNG_IO_MASK_LOC 0x00f0 /* current location: sig/hdr/data/crc */
+#endif /* IO_STATE */
+
+/* Interlace support. The following macros are always defined so that if
+ * libpng interlace handling is turned off the macros may be used to handle
+ * interlaced images within the application.
+ */
+#define PNG_INTERLACE_ADAM7_PASSES 7
+
+/* Two macros to return the first row and first column of the original,
+ * full, image which appears in a given pass. 'pass' is in the range 0
+ * to 6 and the result is in the range 0 to 7.
+ */
+#define PNG_PASS_START_ROW(pass) (((1&~(pass))<<(3-((pass)>>1)))&7)
+#define PNG_PASS_START_COL(pass) (((1& (pass))<<(3-(((pass)+1)>>1)))&7)
+
+/* A macro to return the offset between pixels in the output row for a pair of
+ * pixels in the input - effectively the inverse of the 'COL_SHIFT' macro that
+ * follows. Note that ROW_OFFSET is the offset from one row to the next whereas
+ * COL_OFFSET is from one column to the next, within a row.
+ */
+#define PNG_PASS_ROW_OFFSET(pass) ((pass)>2?(8>>(((pass)-1)>>1)):8)
+#define PNG_PASS_COL_OFFSET(pass) (1<<((7-(pass))>>1))
+
+/* Two macros to help evaluate the number of rows or columns in each
+ * pass. This is expressed as a shift - effectively log2 of the number or
+ * rows or columns in each 8x8 tile of the original image.
+ */
+#define PNG_PASS_ROW_SHIFT(pass) ((pass)>2?(8-(pass))>>1:3)
+#define PNG_PASS_COL_SHIFT(pass) ((pass)>1?(7-(pass))>>1:3)
+
+/* Hence two macros to determine the number of rows or columns in a given
+ * pass of an image given its height or width. In fact these macros may
+ * return non-zero even though the sub-image is empty, because the other
+ * dimension may be empty for a small image.
+ */
+#define PNG_PASS_ROWS(height, pass) (((height)+(((1<<PNG_PASS_ROW_SHIFT(pass))\
+ -1)-PNG_PASS_START_ROW(pass)))>>PNG_PASS_ROW_SHIFT(pass))
+#define PNG_PASS_COLS(width, pass) (((width)+(((1<<PNG_PASS_COL_SHIFT(pass))\
+ -1)-PNG_PASS_START_COL(pass)))>>PNG_PASS_COL_SHIFT(pass))
+
+/* For the reader row callbacks (both progressive and sequential) it is
+ * necessary to find the row in the output image given a row in an interlaced
+ * image, so two more macros:
+ */
+#define PNG_ROW_FROM_PASS_ROW(y_in, pass) \
+ (((y_in)<<PNG_PASS_ROW_SHIFT(pass))+PNG_PASS_START_ROW(pass))
+#define PNG_COL_FROM_PASS_COL(x_in, pass) \
+ (((x_in)<<PNG_PASS_COL_SHIFT(pass))+PNG_PASS_START_COL(pass))
+
+/* Two macros which return a boolean (0 or 1) saying whether the given row
+ * or column is in a particular pass. These use a common utility macro that
+ * returns a mask for a given pass - the offset 'off' selects the row or
+ * column version. The mask has the appropriate bit set for each column in
+ * the tile.
+ */
+#define PNG_PASS_MASK(pass,off) ( \
+ ((0x110145AF>>(((7-(off))-(pass))<<2)) & 0xF) | \
+ ((0x01145AF0>>(((7-(off))-(pass))<<2)) & 0xF0))
+
+#define PNG_ROW_IN_INTERLACE_PASS(y, pass) \
+ ((PNG_PASS_MASK(pass,0) >> ((y)&7)) & 1)
+#define PNG_COL_IN_INTERLACE_PASS(x, pass) \
+ ((PNG_PASS_MASK(pass,1) >> ((x)&7)) & 1)
+
+#ifdef PNG_READ_COMPOSITE_NODIV_SUPPORTED
+/* With these routines we avoid an integer divide, which will be slower on
+ * most machines. However, it does take more operations than the corresponding
+ * divide method, so it may be slower on a few RISC systems. There are two
+ * shifts (by 8 or 16 bits) and an addition, versus a single integer divide.
+ *
+ * Note that the rounding factors are NOT supposed to be the same! 128 and
+ * 32768 are correct for the NODIV code; 127 and 32767 are correct for the
+ * standard method.
+ *
+ * [Optimized code by Greg Roelofs and Mark Adler...blame us for bugs. :-) ]
+ */
+
+ /* fg and bg should be in `gamma 1.0' space; alpha is the opacity */
+
+# define png_composite(composite, fg, alpha, bg) \
+ { png_uint_16 temp = (png_uint_16)((png_uint_16)(fg) \
+ * (png_uint_16)(alpha) \
+ + (png_uint_16)(bg)*(png_uint_16)(255 \
+ - (png_uint_16)(alpha)) + 128); \
+ (composite) = (png_byte)(((temp + (temp >> 8)) >> 8) & 0xff); }
+
+# define png_composite_16(composite, fg, alpha, bg) \
+ { png_uint_32 temp = (png_uint_32)((png_uint_32)(fg) \
+ * (png_uint_32)(alpha) \
+ + (png_uint_32)(bg)*(65535 \
+ - (png_uint_32)(alpha)) + 32768); \
+ (composite) = (png_uint_16)(0xffff & ((temp + (temp >> 16)) >> 16)); }
+
+#else /* Standard method using integer division */
+
+# define png_composite(composite, fg, alpha, bg) \
+ (composite) = \
+ (png_byte)(0xff & (((png_uint_16)(fg) * (png_uint_16)(alpha) + \
+ (png_uint_16)(bg) * (png_uint_16)(255 - (png_uint_16)(alpha)) + \
+ 127) / 255))
+
+# define png_composite_16(composite, fg, alpha, bg) \
+ (composite) = \
+ (png_uint_16)(0xffff & (((png_uint_32)(fg) * (png_uint_32)(alpha) + \
+ (png_uint_32)(bg)*(png_uint_32)(65535 - (png_uint_32)(alpha)) + \
+ 32767) / 65535))
+#endif /* READ_COMPOSITE_NODIV */
+
+#ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
+PNG_EXPORT(201, png_uint_32, png_get_uint_32, (png_const_bytep buf));
+PNG_EXPORT(202, png_uint_16, png_get_uint_16, (png_const_bytep buf));
+PNG_EXPORT(203, png_int_32, png_get_int_32, (png_const_bytep buf));
+#endif
+
+PNG_EXPORT(204, png_uint_32, png_get_uint_31, (png_const_structrp png_ptr,
+ png_const_bytep buf));
+/* No png_get_int_16 -- may be added if there's a real need for it. */
+
+/* Place a 32-bit number into a buffer in PNG byte order (big-endian). */
+#ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
+PNG_EXPORT(205, void, png_save_uint_32, (png_bytep buf, png_uint_32 i));
+#endif
+#ifdef PNG_SAVE_INT_32_SUPPORTED
+PNG_EXPORT(206, void, png_save_int_32, (png_bytep buf, png_int_32 i));
+#endif
+
+/* Place a 16-bit number into a buffer in PNG byte order.
+ * The parameter is declared unsigned int, not png_uint_16,
+ * just to avoid potential problems on pre-ANSI C compilers.
+ */
+#ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
+PNG_EXPORT(207, void, png_save_uint_16, (png_bytep buf, unsigned int i));
+/* No png_save_int_16 -- may be added if there's a real need for it. */
+#endif
+
+#ifdef PNG_USE_READ_MACROS
+/* Inline macros to do direct reads of bytes from the input buffer.
+ * The png_get_int_32() routine assumes we are using two's complement
+ * format for negative values, which is almost certainly true.
+ */
+# define PNG_get_uint_32(buf) \
+ (((png_uint_32)(*(buf)) << 24) + \
+ ((png_uint_32)(*((buf) + 1)) << 16) + \
+ ((png_uint_32)(*((buf) + 2)) << 8) + \
+ ((png_uint_32)(*((buf) + 3))))
+
+ /* From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
+ * function) incorrectly returned a value of type png_uint_32.
+ */
+# define PNG_get_uint_16(buf) \
+ ((png_uint_16) \
+ (((unsigned int)(*(buf)) << 8) + \
+ ((unsigned int)(*((buf) + 1)))))
+
+# define PNG_get_int_32(buf) \
+ ((png_int_32)((*(buf) & 0x80) \
+ ? -((png_int_32)(((png_get_uint_32(buf)^0xffffffffU)+1U)&0x7fffffffU)) \
+ : (png_int_32)png_get_uint_32(buf)))
+
+ /* If PNG_PREFIX is defined the same thing as below happens in pnglibconf.h,
+ * but defining a macro name prefixed with PNG_PREFIX.
+ */
+# ifndef PNG_PREFIX
+# define png_get_uint_32(buf) PNG_get_uint_32(buf)
+# define png_get_uint_16(buf) PNG_get_uint_16(buf)
+# define png_get_int_32(buf) PNG_get_int_32(buf)
+# endif
+#else
+# ifdef PNG_PREFIX
+ /* No macros; revert to the (redefined) function */
+# define PNG_get_uint_32 (png_get_uint_32)
+# define PNG_get_uint_16 (png_get_uint_16)
+# define PNG_get_int_32 (png_get_int_32)
+# endif
+#endif
+
+#ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
+PNG_EXPORT(242, void, png_set_check_for_invalid_index,
+ (png_structrp png_ptr, int allowed));
+# ifdef PNG_GET_PALETTE_MAX_SUPPORTED
+PNG_EXPORT(243, int, png_get_palette_max, (png_const_structp png_ptr,
+ png_const_infop info_ptr));
+# endif
+#endif /* CHECK_FOR_INVALID_INDEX */
+
+/*******************************************************************************
+ * Section 5: SIMPLIFIED API
+ *******************************************************************************
+ *
+ * Please read the documentation in libpng-manual.txt (TODO: write said
+ * documentation) if you don't understand what follows.
+ *
+ * The simplified API hides the details of both libpng and the PNG file format
+ * itself. It allows PNG files to be read into a very limited number of
+ * in-memory bitmap formats or to be written from the same formats. If these
+ * formats do not accomodate your needs then you can, and should, use the more
+ * sophisticated APIs above - these support a wide variety of in-memory formats
+ * and a wide variety of sophisticated transformations to those formats as well
+ * as a wide variety of APIs to manipulate ancillary information.
+ *
+ * To read a PNG file using the simplified API:
+ *
+ * 1) Declare a 'png_image' structure (see below) on the stack, set the
+ * version field to PNG_IMAGE_VERSION and the 'opaque' pointer to NULL
+ * (this is REQUIRED, your program may crash if you don't do it.)
+ * 2) Call the appropriate png_image_begin_read... function.
+ * 3) Set the png_image 'format' member to the required sample format.
+ * 4) Allocate a buffer for the image and, if required, the color-map.
+ * 5) Call png_image_finish_read to read the image and, if required, the
+ * color-map into your buffers.
+ *
+ * There are no restrictions on the format of the PNG input itself; all valid
+ * color types, bit depths, and interlace methods are acceptable, and the
+ * input image is transformed as necessary to the requested in-memory format
+ * during the png_image_finish_read() step. The only caveat is that if you
+ * request a color-mapped image from a PNG that is full-color or makes
+ * complex use of an alpha channel the transformation is extremely lossy and the
+ * result may look terrible.
+ *
+ * To write a PNG file using the simplified API:
+ *
+ * 1) Declare a 'png_image' structure on the stack and memset() it to all zero.
+ * 2) Initialize the members of the structure that describe the image, setting
+ * the 'format' member to the format of the image samples.
+ * 3) Call the appropriate png_image_write... function with a pointer to the
+ * image and, if necessary, the color-map to write the PNG data.
+ *
+ * png_image is a structure that describes the in-memory format of an image
+ * when it is being read or defines the in-memory format of an image that you
+ * need to write:
+ */
+#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) || \
+ defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
+
+#define PNG_IMAGE_VERSION 1
+
+typedef struct png_control *png_controlp;
+typedef struct
+{
+ png_controlp opaque; /* Initialize to NULL, free with png_image_free */
+ png_uint_32 version; /* Set to PNG_IMAGE_VERSION */
+ png_uint_32 width; /* Image width in pixels (columns) */
+ png_uint_32 height; /* Image height in pixels (rows) */
+ png_uint_32 format; /* Image format as defined below */
+ png_uint_32 flags; /* A bit mask containing informational flags */
+ png_uint_32 colormap_entries;
+ /* Number of entries in the color-map */
+
+ /* In the event of an error or warning the following field will be set to a
+ * non-zero value and the 'message' field will contain a '\0' terminated
+ * string with the libpng error or warning message. If both warnings and
+ * an error were encountered, only the error is recorded. If there
+ * are multiple warnings, only the first one is recorded.
+ *
+ * The upper 30 bits of this value are reserved, the low two bits contain
+ * a value as follows:
+ */
+# define PNG_IMAGE_WARNING 1
+# define PNG_IMAGE_ERROR 2
+ /*
+ * The result is a two-bit code such that a value more than 1 indicates
+ * a failure in the API just called:
+ *
+ * 0 - no warning or error
+ * 1 - warning
+ * 2 - error
+ * 3 - error preceded by warning
+ */
+# define PNG_IMAGE_FAILED(png_cntrl) ((((png_cntrl).warning_or_error)&0x03)>1)
+
+ png_uint_32 warning_or_error;
+
+ char message[64];
+} png_image, *png_imagep;
+
+/* The samples of the image have one to four channels whose components have
+ * original values in the range 0 to 1.0:
+ *
+ * 1: A single gray or luminance channel (G).
+ * 2: A gray/luminance channel and an alpha channel (GA).
+ * 3: Three red, green, blue color channels (RGB).
+ * 4: Three color channels and an alpha channel (RGBA).
+ *
+ * The components are encoded in one of two ways:
+ *
+ * a) As a small integer, value 0..255, contained in a single byte. For the
+ * alpha channel the original value is simply value/255. For the color or
+ * luminance channels the value is encoded according to the sRGB specification
+ * and matches the 8-bit format expected by typical display devices.
+ *
+ * The color/gray channels are not scaled (pre-multiplied) by the alpha
+ * channel and are suitable for passing to color management software.
+ *
+ * b) As a value in the range 0..65535, contained in a 2-byte integer. All
+ * channels can be converted to the original value by dividing by 65535; all
+ * channels are linear. Color channels use the RGB encoding (RGB end-points) of
+ * the sRGB specification. This encoding is identified by the
+ * PNG_FORMAT_FLAG_LINEAR flag below.
+ *
+ * When the simplified API needs to convert between sRGB and linear colorspaces,
+ * the actual sRGB transfer curve defined in the sRGB specification (see the
+ * article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
+ * approximation used elsewhere in libpng.
+ *
+ * When an alpha channel is present it is expected to denote pixel coverage
+ * of the color or luminance channels and is returned as an associated alpha
+ * channel: the color/gray channels are scaled (pre-multiplied) by the alpha
+ * value.
+ *
+ * The samples are either contained directly in the image data, between 1 and 8
+ * bytes per pixel according to the encoding, or are held in a color-map indexed
+ * by bytes in the image data. In the case of a color-map the color-map entries
+ * are individual samples, encoded as above, and the image data has one byte per
+ * pixel to select the relevant sample from the color-map.
+ */
+
+/* PNG_FORMAT_*
+ *
+ * #defines to be used in png_image::format. Each #define identifies a
+ * particular layout of sample data and, if present, alpha values. There are
+ * separate defines for each of the two component encodings.
+ *
+ * A format is built up using single bit flag values. All combinations are
+ * valid. Formats can be built up from the flag values or you can use one of
+ * the predefined values below. When testing formats always use the FORMAT_FLAG
+ * macros to test for individual features - future versions of the library may
+ * add new flags.
+ *
+ * When reading or writing color-mapped images the format should be set to the
+ * format of the entries in the color-map then png_image_{read,write}_colormap
+ * called to read or write the color-map and set the format correctly for the
+ * image data. Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly!
+ *
+ * NOTE: libpng can be built with particular features disabled. If you see
+ * compiler errors because the definition of one of the following flags has been
+ * compiled out it is because libpng does not have the required support. It is
+ * possible, however, for the libpng configuration to enable the format on just
+ * read or just write; in that case you may see an error at run time. You can
+ * guard against this by checking for the definition of the appropriate
+ * "_SUPPORTED" macro, one of:
+ *
+ * PNG_SIMPLIFIED_{READ,WRITE}_{BGR,AFIRST}_SUPPORTED
+ */
+#define PNG_FORMAT_FLAG_ALPHA 0x01U /* format with an alpha channel */
+#define PNG_FORMAT_FLAG_COLOR 0x02U /* color format: otherwise grayscale */
+#define PNG_FORMAT_FLAG_LINEAR 0x04U /* 2-byte channels else 1-byte */
+#define PNG_FORMAT_FLAG_COLORMAP 0x08U /* image data is color-mapped */
+
+#ifdef PNG_FORMAT_BGR_SUPPORTED
+# define PNG_FORMAT_FLAG_BGR 0x10U /* BGR colors, else order is RGB */
+#endif
+
+#ifdef PNG_FORMAT_AFIRST_SUPPORTED
+# define PNG_FORMAT_FLAG_AFIRST 0x20U /* alpha channel comes first */
+#endif
+
+/* Commonly used formats have predefined macros.
+ *
+ * First the single byte (sRGB) formats:
+ */
+#define PNG_FORMAT_GRAY 0
+#define PNG_FORMAT_GA PNG_FORMAT_FLAG_ALPHA
+#define PNG_FORMAT_AG (PNG_FORMAT_GA|PNG_FORMAT_FLAG_AFIRST)
+#define PNG_FORMAT_RGB PNG_FORMAT_FLAG_COLOR
+#define PNG_FORMAT_BGR (PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_BGR)
+#define PNG_FORMAT_RGBA (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_ALPHA)
+#define PNG_FORMAT_ARGB (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_AFIRST)
+#define PNG_FORMAT_BGRA (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_ALPHA)
+#define PNG_FORMAT_ABGR (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_AFIRST)
+
+/* Then the linear 2-byte formats. When naming these "Y" is used to
+ * indicate a luminance (gray) channel.
+ */
+#define PNG_FORMAT_LINEAR_Y PNG_FORMAT_FLAG_LINEAR
+#define PNG_FORMAT_LINEAR_Y_ALPHA (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_ALPHA)
+#define PNG_FORMAT_LINEAR_RGB (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR)
+#define PNG_FORMAT_LINEAR_RGB_ALPHA \
+ (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA)
+
+/* With color-mapped formats the image data is one byte for each pixel, the byte
+ * is an index into the color-map which is formatted as above. To obtain a
+ * color-mapped format it is sufficient just to add the PNG_FOMAT_FLAG_COLORMAP
+ * to one of the above definitions, or you can use one of the definitions below.
+ */
+#define PNG_FORMAT_RGB_COLORMAP (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_COLORMAP)
+#define PNG_FORMAT_BGR_COLORMAP (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_COLORMAP)
+#define PNG_FORMAT_RGBA_COLORMAP (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_COLORMAP)
+#define PNG_FORMAT_ARGB_COLORMAP (PNG_FORMAT_ARGB|PNG_FORMAT_FLAG_COLORMAP)
+#define PNG_FORMAT_BGRA_COLORMAP (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_COLORMAP)
+#define PNG_FORMAT_ABGR_COLORMAP (PNG_FORMAT_ABGR|PNG_FORMAT_FLAG_COLORMAP)
+
+/* PNG_IMAGE macros
+ *
+ * These are convenience macros to derive information from a png_image
+ * structure. The PNG_IMAGE_SAMPLE_ macros return values appropriate to the
+ * actual image sample values - either the entries in the color-map or the
+ * pixels in the image. The PNG_IMAGE_PIXEL_ macros return corresponding values
+ * for the pixels and will always return 1 for color-mapped formats. The
+ * remaining macros return information about the rows in the image and the
+ * complete image.
+ *
+ * NOTE: All the macros that take a png_image::format parameter are compile time
+ * constants if the format parameter is, itself, a constant. Therefore these
+ * macros can be used in array declarations and case labels where required.
+ * Similarly the macros are also pre-processor constants (sizeof is not used) so
+ * they can be used in #if tests.
+ *
+ * First the information about the samples.
+ */
+#define PNG_IMAGE_SAMPLE_CHANNELS(fmt)\
+ (((fmt)&(PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA))+1)
+ /* Return the total number of channels in a given format: 1..4 */
+
+#define PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt)\
+ ((((fmt) & PNG_FORMAT_FLAG_LINEAR) >> 2)+1)
+ /* Return the size in bytes of a single component of a pixel or color-map
+ * entry (as appropriate) in the image: 1 or 2.
+ */
+
+#define PNG_IMAGE_SAMPLE_SIZE(fmt)\
+ (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt))
+ /* This is the size of the sample data for one sample. If the image is
+ * color-mapped it is the size of one color-map entry (and image pixels are
+ * one byte in size), otherwise it is the size of one image pixel.
+ */
+
+#define PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)\
+ (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * 256)
+ /* The maximum size of the color-map required by the format expressed in a
+ * count of components. This can be used to compile-time allocate a
+ * color-map:
+ *
+ * png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)];
+ *
+ * png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)];
+ *
+ * Alternatively use the PNG_IMAGE_COLORMAP_SIZE macro below to use the
+ * information from one of the png_image_begin_read_ APIs and dynamically
+ * allocate the required memory.
+ */
+
+/* Corresponding information about the pixels */
+#define PNG_IMAGE_PIXEL_(test,fmt)\
+ (((fmt)&PNG_FORMAT_FLAG_COLORMAP)?1:test(fmt))
+
+#define PNG_IMAGE_PIXEL_CHANNELS(fmt)\
+ PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_CHANNELS,fmt)
+ /* The number of separate channels (components) in a pixel; 1 for a
+ * color-mapped image.
+ */
+
+#define PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)\
+ PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_COMPONENT_SIZE,fmt)
+ /* The size, in bytes, of each component in a pixel; 1 for a color-mapped
+ * image.
+ */
+
+#define PNG_IMAGE_PIXEL_SIZE(fmt) PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_SIZE,fmt)
+ /* The size, in bytes, of a complete pixel; 1 for a color-mapped image. */
+
+/* Information about the whole row, or whole image */
+#define PNG_IMAGE_ROW_STRIDE(image)\
+ (PNG_IMAGE_PIXEL_CHANNELS((image).format) * (image).width)
+ /* Return the total number of components in a single row of the image; this
+ * is the minimum 'row stride', the minimum count of components between each
+ * row. For a color-mapped image this is the minimum number of bytes in a
+ * row.
+ */
+
+#define PNG_IMAGE_BUFFER_SIZE(image, row_stride)\
+ (PNG_IMAGE_PIXEL_COMPONENT_SIZE((image).format)*(image).height*(row_stride))
+ /* Return the size, in bytes, of an image buffer given a png_image and a row
+ * stride - the number of components to leave space for in each row.
+ */
+
+#define PNG_IMAGE_SIZE(image)\
+ PNG_IMAGE_BUFFER_SIZE(image, PNG_IMAGE_ROW_STRIDE(image))
+ /* Return the size, in bytes, of the image in memory given just a png_image;
+ * the row stride is the minimum stride required for the image.
+ */
+
+#define PNG_IMAGE_COLORMAP_SIZE(image)\
+ (PNG_IMAGE_SAMPLE_SIZE((image).format) * (image).colormap_entries)
+ /* Return the size, in bytes, of the color-map of this image. If the image
+ * format is not a color-map format this will return a size sufficient for
+ * 256 entries in the given format; check PNG_FORMAT_FLAG_COLORMAP if
+ * you don't want to allocate a color-map in this case.
+ */
+
+/* PNG_IMAGE_FLAG_*
+ *
+ * Flags containing additional information about the image are held in the
+ * 'flags' field of png_image.
+ */
+#define PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB 0x01
+ /* This indicates the the RGB values of the in-memory bitmap do not
+ * correspond to the red, green and blue end-points defined by sRGB.
+ */
+
+#define PNG_IMAGE_FLAG_FAST 0x02
+ /* On write emphasise speed over compression; the resultant PNG file will be
+ * larger but will be produced significantly faster, particular for large
+ * images. Do not use this option for images which will be distributed, only
+ * used it when producing intermediate files that will be read back in
+ * repeatedly. For a typical 24-bit image the option will double the read
+ * speed at the cost of increasing the image size by 25%, however for many
+ * more compressible images the PNG file can be 10 times larger with only a
+ * slight speed gain.
+ */
+
+#define PNG_IMAGE_FLAG_16BIT_sRGB 0x04
+ /* On read if the image is a 16-bit per component image and there is no gAMA
+ * or sRGB chunk assume that the components are sRGB encoded. Notice that
+ * images output by the simplified API always have gamma information; setting
+ * this flag only affects the interpretation of 16-bit images from an
+ * external source. It is recommended that the application expose this flag
+ * to the user; the user can normally easily recognize the difference between
+ * linear and sRGB encoding. This flag has no effect on write - the data
+ * passed to the write APIs must have the correct encoding (as defined
+ * above.)
+ *
+ * If the flag is not set (the default) input 16-bit per component data is
+ * assumed to be linear.
+ *
+ * NOTE: the flag can only be set after the png_image_begin_read_ call,
+ * because that call initializes the 'flags' field.
+ */
+
+#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
+/* READ APIs
+ * ---------
+ *
+ * The png_image passed to the read APIs must have been initialized by setting
+ * the png_controlp field 'opaque' to NULL (or, safer, memset the whole thing.)
+ */
+#ifdef PNG_STDIO_SUPPORTED
+PNG_EXPORT(234, int, png_image_begin_read_from_file, (png_imagep image,
+ const char *file_name));
+ /* The named file is opened for read and the image header is filled in
+ * from the PNG header in the file.
+ */
+
+PNG_EXPORT(235, int, png_image_begin_read_from_stdio, (png_imagep image,
+ FILE* file));
+ /* The PNG header is read from the stdio FILE object. */
+#endif /* STDIO */
+
+PNG_EXPORT(236, int, png_image_begin_read_from_memory, (png_imagep image,
+ png_const_voidp memory, png_size_t size));
+ /* The PNG header is read from the given memory buffer. */
+
+PNG_EXPORT(237, int, png_image_finish_read, (png_imagep image,
+ png_const_colorp background, void *buffer, png_int_32 row_stride,
+ void *colormap));
+ /* Finish reading the image into the supplied buffer and clean up the
+ * png_image structure.
+ *
+ * row_stride is the step, in byte or 2-byte units as appropriate,
+ * between adjacent rows. A positive stride indicates that the top-most row
+ * is first in the buffer - the normal top-down arrangement. A negative
+ * stride indicates that the bottom-most row is first in the buffer.
+ *
+ * background need only be supplied if an alpha channel must be removed from
+ * a png_byte format and the removal is to be done by compositing on a solid
+ * color; otherwise it may be NULL and any composition will be done directly
+ * onto the buffer. The value is an sRGB color to use for the background,
+ * for grayscale output the green channel is used.
+ *
+ * background must be supplied when an alpha channel must be removed from a
+ * single byte color-mapped output format, in other words if:
+ *
+ * 1) The original format from png_image_begin_read_from_* had
+ * PNG_FORMAT_FLAG_ALPHA set.
+ * 2) The format set by the application does not.
+ * 3) The format set by the application has PNG_FORMAT_FLAG_COLORMAP set and
+ * PNG_FORMAT_FLAG_LINEAR *not* set.
+ *
+ * For linear output removing the alpha channel is always done by compositing
+ * on black and background is ignored.
+ *
+ * colormap must be supplied when PNG_FORMAT_FLAG_COLORMAP is set. It must
+ * be at least the size (in bytes) returned by PNG_IMAGE_COLORMAP_SIZE.
+ * image->colormap_entries will be updated to the actual number of entries
+ * written to the colormap; this may be less than the original value.
+ */
+
+PNG_EXPORT(238, void, png_image_free, (png_imagep image));
+ /* Free any data allocated by libpng in image->opaque, setting the pointer to
+ * NULL. May be called at any time after the structure is initialized.
+ */
+#endif /* SIMPLIFIED_READ */
+
+#ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
+#ifdef PNG_STDIO_SUPPORTED
+/* WRITE APIS
+ * ----------
+ * For write you must initialize a png_image structure to describe the image to
+ * be written. To do this use memset to set the whole structure to 0 then
+ * initialize fields describing your image.
+ *
+ * version: must be set to PNG_IMAGE_VERSION
+ * opaque: must be initialized to NULL
+ * width: image width in pixels
+ * height: image height in rows
+ * format: the format of the data (image and color-map) you wish to write
+ * flags: set to 0 unless one of the defined flags applies; set
+ * PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB for color format images where the RGB
+ * values do not correspond to the colors in sRGB.
+ * colormap_entries: set to the number of entries in the color-map (0 to 256)
+ */
+PNG_EXPORT(239, int, png_image_write_to_file, (png_imagep image,
+ const char *file, int convert_to_8bit, const void *buffer,
+ png_int_32 row_stride, const void *colormap));
+ /* Write the image to the named file. */
+
+PNG_EXPORT(240, int, png_image_write_to_stdio, (png_imagep image, FILE *file,
+ int convert_to_8_bit, const void *buffer, png_int_32 row_stride,
+ const void *colormap));
+ /* Write the image to the given (FILE*). */
+
+/* With both write APIs if image is in one of the linear formats with 16-bit
+ * data then setting convert_to_8_bit will cause the output to be an 8-bit PNG
+ * gamma encoded according to the sRGB specification, otherwise a 16-bit linear
+ * encoded PNG file is written.
+ *
+ * With color-mapped data formats the colormap parameter point to a color-map
+ * with at least image->colormap_entries encoded in the specified format. If
+ * the format is linear the written PNG color-map will be converted to sRGB
+ * regardless of the convert_to_8_bit flag.
+ *
+ * With all APIs row_stride is handled as in the read APIs - it is the spacing
+ * from one row to the next in component sized units (1 or 2 bytes) and if
+ * negative indicates a bottom-up row layout in the buffer. If row_stride is zero,
+ * libpng will calculate it for you from the image width and number of channels.
+ *
+ * Note that the write API does not support interlacing, sub-8-bit pixels, indexed
+ * PNG (color_type 3) or most ancillary chunks.
+ */
+#endif /* STDIO */
+#endif /* SIMPLIFIED_WRITE */
+/*******************************************************************************
+ * END OF SIMPLIFIED API
+ ******************************************************************************/
+#endif /* SIMPLIFIED_{READ|WRITE} */
+
+/*******************************************************************************
+ * Section 6: IMPLEMENTATION OPTIONS
+ *******************************************************************************
+ *
+ * Support for arbitrary implementation-specific optimizations. The API allows
+ * particular options to be turned on or off. 'Option' is the number of the
+ * option and 'onoff' is 0 (off) or non-0 (on). The value returned is given
+ * by the PNG_OPTION_ defines below.
+ *
+ * HARDWARE: normally hardware capabilites, such as the Intel SSE instructions,
+ * are detected at run time, however sometimes it may be impossible
+ * to do this in user mode, in which case it is necessary to discover
+ * the capabilities in an OS specific way. Such capabilities are
+ * listed here when libpng has support for them and must be turned
+ * ON by the application if present.
+ *
+ * SOFTWARE: sometimes software optimizations actually result in performance
+ * decrease on some architectures or systems, or with some sets of
+ * PNG images. 'Software' options allow such optimizations to be
+ * selected at run time.
+ */
+#ifdef PNG_SET_OPTION_SUPPORTED
+#ifdef PNG_ARM_NEON_API_SUPPORTED
+# define PNG_ARM_NEON 0 /* HARDWARE: ARM Neon SIMD instructions supported */
+#endif
+#define PNG_MAXIMUM_INFLATE_WINDOW 2 /* SOFTWARE: force maximum window */
+#define PNG_SKIP_sRGB_CHECK_PROFILE 4 /* SOFTWARE: Check ICC profile for sRGB */
+#define PNG_OPTION_NEXT 6 /* Next option - numbers must be even */
+
+/* Return values: NOTE: there are four values and 'off' is *not* zero */
+#define PNG_OPTION_UNSET 0 /* Unset - defaults to off */
+#define PNG_OPTION_INVALID 1 /* Option number out of range */
+#define PNG_OPTION_OFF 2
+#define PNG_OPTION_ON 3
+
+PNG_EXPORT(244, int, png_set_option, (png_structrp png_ptr, int option,
+ int onoff));
+#endif /* SET_OPTION */
+
+/*******************************************************************************
+ * END OF HARDWARE AND SOFTWARE OPTIONS
+ ******************************************************************************/
+
+/* Maintainer: Put new public prototypes here ^, in libpng.3, in project
+ * defs, and in scripts/symbols.def.
+ */
+
+/* The last ordinal number (this is the *last* one already used; the next
+ * one to use is one more than this.)
+ */
+#ifdef PNG_EXPORT_LAST_ORDINAL
+ PNG_EXPORT_LAST_ORDINAL(244);
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* PNG_VERSION_INFO_ONLY */
+/* Do not put anything past this line */
+#endif /* PNG_H */
diff --git a/libpng/pngbar.jpg b/libpng/pngbar.jpg
new file mode 100644
index 0000000..70ba8d8
--- /dev/null
+++ b/libpng/pngbar.jpg
Binary files differ
diff --git a/libpng/pngbar.png b/libpng/pngbar.png
new file mode 100644
index 0000000..49798c8
--- /dev/null
+++ b/libpng/pngbar.png
Binary files differ
diff --git a/libpng/pngconf.h b/libpng/pngconf.h
new file mode 100644
index 0000000..92f2500
--- /dev/null
+++ b/libpng/pngconf.h
@@ -0,0 +1,622 @@
+
+/* pngconf.h - machine configurable file for libpng
+ *
+ * libpng version 1.6.20, December 3, 2015
+ *
+ * Copyright (c) 1998-2015 Glenn Randers-Pehrson
+ * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ *
+ * Any machine specific code is near the front of this file, so if you
+ * are configuring libpng for a machine, you may want to read the section
+ * starting here down to where it starts to typedef png_color, png_text,
+ * and png_info.
+ */
+
+#ifndef PNGCONF_H
+#define PNGCONF_H
+
+#ifndef PNG_BUILDING_SYMBOL_TABLE /* else includes may cause problems */
+
+/* From libpng 1.6.0 libpng requires an ANSI X3.159-1989 ("ISOC90") compliant C
+ * compiler for correct compilation. The following header files are required by
+ * the standard. If your compiler doesn't provide these header files, or they
+ * do not match the standard, you will need to provide/improve them.
+ */
+#include <limits.h>
+#include <stddef.h>
+
+/* Library header files. These header files are all defined by ISOC90; libpng
+ * expects conformant implementations, however, an ISOC90 conformant system need
+ * not provide these header files if the functionality cannot be implemented.
+ * In this case it will be necessary to disable the relevant parts of libpng in
+ * the build of pnglibconf.h.
+ *
+ * Prior to 1.6.0 string.h was included here; the API changes in 1.6.0 to not
+ * include this unnecessary header file.
+ */
+
+#ifdef PNG_STDIO_SUPPORTED
+ /* Required for the definition of FILE: */
+# include <stdio.h>
+#endif
+
+#ifdef PNG_SETJMP_SUPPORTED
+ /* Required for the definition of jmp_buf and the declaration of longjmp: */
+# include <setjmp.h>
+#endif
+
+#ifdef PNG_CONVERT_tIME_SUPPORTED
+ /* Required for struct tm: */
+# include <time.h>
+#endif
+
+#endif /* PNG_BUILDING_SYMBOL_TABLE */
+
+/* Prior to 1.6.0 it was possible to turn off 'const' in declarations using
+ * PNG_NO_CONST; this is no longer supported except for data declarations which
+ * apparently still cause problems in 2011 on some compilers.
+ */
+#define PNG_CONST const /* backward compatibility only */
+
+/* This controls optimization of the reading of 16-bit and 32-bit values
+ * from PNG files. It can be set on a per-app-file basis - it
+ * just changes whether a macro is used when the function is called.
+ * The library builder sets the default; if read functions are not
+ * built into the library the macro implementation is forced on.
+ */
+#ifndef PNG_READ_INT_FUNCTIONS_SUPPORTED
+# define PNG_USE_READ_MACROS
+#endif
+#if !defined(PNG_NO_USE_READ_MACROS) && !defined(PNG_USE_READ_MACROS)
+# if PNG_DEFAULT_READ_MACROS
+# define PNG_USE_READ_MACROS
+# endif
+#endif
+
+/* COMPILER SPECIFIC OPTIONS.
+ *
+ * These options are provided so that a variety of difficult compilers
+ * can be used. Some are fixed at build time (e.g. PNG_API_RULE
+ * below) but still have compiler specific implementations, others
+ * may be changed on a per-file basis when compiling against libpng.
+ */
+
+/* The PNGARG macro was used in versions of libpng prior to 1.6.0 to protect
+ * against legacy (pre ISOC90) compilers that did not understand function
+ * prototypes. It is not required for modern C compilers.
+ */
+#ifndef PNGARG
+# define PNGARG(arglist) arglist
+#endif
+
+/* Function calling conventions.
+ * =============================
+ * Normally it is not necessary to specify to the compiler how to call
+ * a function - it just does it - however on x86 systems derived from
+ * Microsoft and Borland C compilers ('IBM PC', 'DOS', 'Windows' systems
+ * and some others) there are multiple ways to call a function and the
+ * default can be changed on the compiler command line. For this reason
+ * libpng specifies the calling convention of every exported function and
+ * every function called via a user supplied function pointer. This is
+ * done in this file by defining the following macros:
+ *
+ * PNGAPI Calling convention for exported functions.
+ * PNGCBAPI Calling convention for user provided (callback) functions.
+ * PNGCAPI Calling convention used by the ANSI-C library (required
+ * for longjmp callbacks and sometimes used internally to
+ * specify the calling convention for zlib).
+ *
+ * These macros should never be overridden. If it is necessary to
+ * change calling convention in a private build this can be done
+ * by setting PNG_API_RULE (which defaults to 0) to one of the values
+ * below to select the correct 'API' variants.
+ *
+ * PNG_API_RULE=0 Use PNGCAPI - the 'C' calling convention - throughout.
+ * This is correct in every known environment.
+ * PNG_API_RULE=1 Use the operating system convention for PNGAPI and
+ * the 'C' calling convention (from PNGCAPI) for
+ * callbacks (PNGCBAPI). This is no longer required
+ * in any known environment - if it has to be used
+ * please post an explanation of the problem to the
+ * libpng mailing list.
+ *
+ * These cases only differ if the operating system does not use the C
+ * calling convention, at present this just means the above cases
+ * (x86 DOS/Windows sytems) and, even then, this does not apply to
+ * Cygwin running on those systems.
+ *
+ * Note that the value must be defined in pnglibconf.h so that what
+ * the application uses to call the library matches the conventions
+ * set when building the library.
+ */
+
+/* Symbol export
+ * =============
+ * When building a shared library it is almost always necessary to tell
+ * the compiler which symbols to export. The png.h macro 'PNG_EXPORT'
+ * is used to mark the symbols. On some systems these symbols can be
+ * extracted at link time and need no special processing by the compiler,
+ * on other systems the symbols are flagged by the compiler and just
+ * the declaration requires a special tag applied (unfortunately) in a
+ * compiler dependent way. Some systems can do either.
+ *
+ * A small number of older systems also require a symbol from a DLL to
+ * be flagged to the program that calls it. This is a problem because
+ * we do not know in the header file included by application code that
+ * the symbol will come from a shared library, as opposed to a statically
+ * linked one. For this reason the application must tell us by setting
+ * the magic flag PNG_USE_DLL to turn on the special processing before
+ * it includes png.h.
+ *
+ * Four additional macros are used to make this happen:
+ *
+ * PNG_IMPEXP The magic (if any) to cause a symbol to be exported from
+ * the build or imported if PNG_USE_DLL is set - compiler
+ * and system specific.
+ *
+ * PNG_EXPORT_TYPE(type) A macro that pre or appends PNG_IMPEXP to
+ * 'type', compiler specific.
+ *
+ * PNG_DLL_EXPORT Set to the magic to use during a libpng build to
+ * make a symbol exported from the DLL. Not used in the
+ * public header files; see pngpriv.h for how it is used
+ * in the libpng build.
+ *
+ * PNG_DLL_IMPORT Set to the magic to force the libpng symbols to come
+ * from a DLL - used to define PNG_IMPEXP when
+ * PNG_USE_DLL is set.
+ */
+
+/* System specific discovery.
+ * ==========================
+ * This code is used at build time to find PNG_IMPEXP, the API settings
+ * and PNG_EXPORT_TYPE(), it may also set a macro to indicate the DLL
+ * import processing is possible. On Windows systems it also sets
+ * compiler-specific macros to the values required to change the calling
+ * conventions of the various functions.
+ */
+#if defined(_Windows) || defined(_WINDOWS) || defined(WIN32) ||\
+ defined(_WIN32) || defined(__WIN32__) || defined(__CYGWIN__)
+ /* Windows system (DOS doesn't support DLLs). Includes builds under Cygwin or
+ * MinGW on any architecture currently supported by Windows. Also includes
+ * Watcom builds but these need special treatment because they are not
+ * compatible with GCC or Visual C because of different calling conventions.
+ */
+# if PNG_API_RULE == 2
+ /* If this line results in an error, either because __watcall is not
+ * understood or because of a redefine just below you cannot use *this*
+ * build of the library with the compiler you are using. *This* build was
+ * build using Watcom and applications must also be built using Watcom!
+ */
+# define PNGCAPI __watcall
+# endif
+
+# if defined(__GNUC__) || (defined(_MSC_VER) && (_MSC_VER >= 800))
+# define PNGCAPI __cdecl
+# if PNG_API_RULE == 1
+ /* If this line results in an error __stdcall is not understood and
+ * PNG_API_RULE should not have been set to '1'.
+ */
+# define PNGAPI __stdcall
+# endif
+# else
+ /* An older compiler, or one not detected (erroneously) above,
+ * if necessary override on the command line to get the correct
+ * variants for the compiler.
+ */
+# ifndef PNGCAPI
+# define PNGCAPI _cdecl
+# endif
+# if PNG_API_RULE == 1 && !defined(PNGAPI)
+# define PNGAPI _stdcall
+# endif
+# endif /* compiler/api */
+
+ /* NOTE: PNGCBAPI always defaults to PNGCAPI. */
+
+# if defined(PNGAPI) && !defined(PNG_USER_PRIVATEBUILD)
+# error "PNG_USER_PRIVATEBUILD must be defined if PNGAPI is changed"
+# endif
+
+# if (defined(_MSC_VER) && _MSC_VER < 800) ||\
+ (defined(__BORLANDC__) && __BORLANDC__ < 0x500)
+ /* older Borland and MSC
+ * compilers used '__export' and required this to be after
+ * the type.
+ */
+# ifndef PNG_EXPORT_TYPE
+# define PNG_EXPORT_TYPE(type) type PNG_IMPEXP
+# endif
+# define PNG_DLL_EXPORT __export
+# else /* newer compiler */
+# define PNG_DLL_EXPORT __declspec(dllexport)
+# ifndef PNG_DLL_IMPORT
+# define PNG_DLL_IMPORT __declspec(dllimport)
+# endif
+# endif /* compiler */
+
+#else /* !Windows */
+# if (defined(__IBMC__) || defined(__IBMCPP__)) && defined(__OS2__)
+# define PNGAPI _System
+# else /* !Windows/x86 && !OS/2 */
+ /* Use the defaults, or define PNG*API on the command line (but
+ * this will have to be done for every compile!)
+ */
+# endif /* other system, !OS/2 */
+#endif /* !Windows/x86 */
+
+/* Now do all the defaulting . */
+#ifndef PNGCAPI
+# define PNGCAPI
+#endif
+#ifndef PNGCBAPI
+# define PNGCBAPI PNGCAPI
+#endif
+#ifndef PNGAPI
+# define PNGAPI PNGCAPI
+#endif
+
+/* PNG_IMPEXP may be set on the compilation system command line or (if not set)
+ * then in an internal header file when building the library, otherwise (when
+ * using the library) it is set here.
+ */
+#ifndef PNG_IMPEXP
+# if defined(PNG_USE_DLL) && defined(PNG_DLL_IMPORT)
+ /* This forces use of a DLL, disallowing static linking */
+# define PNG_IMPEXP PNG_DLL_IMPORT
+# endif
+
+# ifndef PNG_IMPEXP
+# define PNG_IMPEXP
+# endif
+#endif
+
+/* In 1.5.2 the definition of PNG_FUNCTION has been changed to always treat
+ * 'attributes' as a storage class - the attributes go at the start of the
+ * function definition, and attributes are always appended regardless of the
+ * compiler. This considerably simplifies these macros but may cause problems
+ * if any compilers both need function attributes and fail to handle them as
+ * a storage class (this is unlikely.)
+ */
+#ifndef PNG_FUNCTION
+# define PNG_FUNCTION(type, name, args, attributes) attributes type name args
+#endif
+
+#ifndef PNG_EXPORT_TYPE
+# define PNG_EXPORT_TYPE(type) PNG_IMPEXP type
+#endif
+
+ /* The ordinal value is only relevant when preprocessing png.h for symbol
+ * table entries, so we discard it here. See the .dfn files in the
+ * scripts directory.
+ */
+
+#ifndef PNG_EXPORTA
+# define PNG_EXPORTA(ordinal, type, name, args, attributes) \
+ PNG_FUNCTION(PNG_EXPORT_TYPE(type), (PNGAPI name), PNGARG(args), \
+ PNG_LINKAGE_API attributes)
+#endif
+
+/* ANSI-C (C90) does not permit a macro to be invoked with an empty argument,
+ * so make something non-empty to satisfy the requirement:
+ */
+#define PNG_EMPTY /*empty list*/
+
+#define PNG_EXPORT(ordinal, type, name, args) \
+ PNG_EXPORTA(ordinal, type, name, args, PNG_EMPTY)
+
+/* Use PNG_REMOVED to comment out a removed interface. */
+#ifndef PNG_REMOVED
+# define PNG_REMOVED(ordinal, type, name, args, attributes)
+#endif
+
+#ifndef PNG_CALLBACK
+# define PNG_CALLBACK(type, name, args) type (PNGCBAPI name) PNGARG(args)
+#endif
+
+/* Support for compiler specific function attributes. These are used
+ * so that where compiler support is available incorrect use of API
+ * functions in png.h will generate compiler warnings.
+ *
+ * Added at libpng-1.2.41.
+ */
+
+#ifndef PNG_NO_PEDANTIC_WARNINGS
+# ifndef PNG_PEDANTIC_WARNINGS_SUPPORTED
+# define PNG_PEDANTIC_WARNINGS_SUPPORTED
+# endif
+#endif
+
+#ifdef PNG_PEDANTIC_WARNINGS_SUPPORTED
+ /* Support for compiler specific function attributes. These are used
+ * so that where compiler support is available, incorrect use of API
+ * functions in png.h will generate compiler warnings. Added at libpng
+ * version 1.2.41. Disabling these removes the warnings but may also produce
+ * less efficient code.
+ */
+# if defined(__clang__) && defined(__has_attribute)
+ /* Clang defines both __clang__ and __GNUC__. Check __clang__ first. */
+# if !defined(PNG_USE_RESULT) && __has_attribute(__warn_unused_result__)
+# define PNG_USE_RESULT __attribute__((__warn_unused_result__))
+# endif
+# if !defined(PNG_NORETURN) && __has_attribute(__noreturn__)
+# define PNG_NORETURN __attribute__((__noreturn__))
+# endif
+# if !defined(PNG_ALLOCATED) && __has_attribute(__malloc__)
+# define PNG_ALLOCATED __attribute__((__malloc__))
+# endif
+# if !defined(PNG_DEPRECATED) && __has_attribute(__deprecated__)
+# define PNG_DEPRECATED __attribute__((__deprecated__))
+# endif
+# if !defined(PNG_PRIVATE)
+# ifdef __has_extension
+# if __has_extension(attribute_unavailable_with_message)
+# define PNG_PRIVATE __attribute__((__unavailable__(\
+ "This function is not exported by libpng.")))
+# endif
+# endif
+# endif
+# ifndef PNG_RESTRICT
+# define PNG_RESTRICT __restrict
+# endif
+
+# elif defined(__GNUC__)
+# ifndef PNG_USE_RESULT
+# define PNG_USE_RESULT __attribute__((__warn_unused_result__))
+# endif
+# ifndef PNG_NORETURN
+# define PNG_NORETURN __attribute__((__noreturn__))
+# endif
+# if __GNUC__ >= 3
+# ifndef PNG_ALLOCATED
+# define PNG_ALLOCATED __attribute__((__malloc__))
+# endif
+# ifndef PNG_DEPRECATED
+# define PNG_DEPRECATED __attribute__((__deprecated__))
+# endif
+# ifndef PNG_PRIVATE
+# if 0 /* Doesn't work so we use deprecated instead*/
+# define PNG_PRIVATE \
+ __attribute__((warning("This function is not exported by libpng.")))
+# else
+# define PNG_PRIVATE \
+ __attribute__((__deprecated__))
+# endif
+# endif
+# if ((__GNUC__ > 3) || !defined(__GNUC_MINOR__) || (__GNUC_MINOR__ >= 1))
+# ifndef PNG_RESTRICT
+# define PNG_RESTRICT __restrict
+# endif
+# endif /* __GNUC__.__GNUC_MINOR__ > 3.0 */
+# endif /* __GNUC__ >= 3 */
+
+# elif defined(_MSC_VER) && (_MSC_VER >= 1300)
+# ifndef PNG_USE_RESULT
+# define PNG_USE_RESULT /* not supported */
+# endif
+# ifndef PNG_NORETURN
+# define PNG_NORETURN __declspec(noreturn)
+# endif
+# ifndef PNG_ALLOCATED
+# if (_MSC_VER >= 1400)
+# define PNG_ALLOCATED __declspec(restrict)
+# endif
+# endif
+# ifndef PNG_DEPRECATED
+# define PNG_DEPRECATED __declspec(deprecated)
+# endif
+# ifndef PNG_PRIVATE
+# define PNG_PRIVATE __declspec(deprecated)
+# endif
+# ifndef PNG_RESTRICT
+# if (_MSC_VER >= 1400)
+# define PNG_RESTRICT __restrict
+# endif
+# endif
+
+# elif defined(__WATCOMC__)
+# ifndef PNG_RESTRICT
+# define PNG_RESTRICT __restrict
+# endif
+# endif
+#endif /* PNG_PEDANTIC_WARNINGS */
+
+#ifndef PNG_DEPRECATED
+# define PNG_DEPRECATED /* Use of this function is deprecated */
+#endif
+#ifndef PNG_USE_RESULT
+# define PNG_USE_RESULT /* The result of this function must be checked */
+#endif
+#ifndef PNG_NORETURN
+# define PNG_NORETURN /* This function does not return */
+#endif
+#ifndef PNG_ALLOCATED
+# define PNG_ALLOCATED /* The result of the function is new memory */
+#endif
+#ifndef PNG_PRIVATE
+# define PNG_PRIVATE /* This is a private libpng function */
+#endif
+#ifndef PNG_RESTRICT
+# define PNG_RESTRICT /* The C99 "restrict" feature */
+#endif
+
+#ifndef PNG_FP_EXPORT /* A floating point API. */
+# ifdef PNG_FLOATING_POINT_SUPPORTED
+# define PNG_FP_EXPORT(ordinal, type, name, args)\
+ PNG_EXPORT(ordinal, type, name, args);
+# else /* No floating point APIs */
+# define PNG_FP_EXPORT(ordinal, type, name, args)
+# endif
+#endif
+#ifndef PNG_FIXED_EXPORT /* A fixed point API. */
+# ifdef PNG_FIXED_POINT_SUPPORTED
+# define PNG_FIXED_EXPORT(ordinal, type, name, args)\
+ PNG_EXPORT(ordinal, type, name, args);
+# else /* No fixed point APIs */
+# define PNG_FIXED_EXPORT(ordinal, type, name, args)
+# endif
+#endif
+
+#ifndef PNG_BUILDING_SYMBOL_TABLE
+/* Some typedefs to get us started. These should be safe on most of the common
+ * platforms.
+ *
+ * png_uint_32 and png_int_32 may, currently, be larger than required to hold a
+ * 32-bit value however this is not normally advisable.
+ *
+ * png_uint_16 and png_int_16 should always be two bytes in size - this is
+ * verified at library build time.
+ *
+ * png_byte must always be one byte in size.
+ *
+ * The checks below use constants from limits.h, as defined by the ISOC90
+ * standard.
+ */
+#if CHAR_BIT == 8 && UCHAR_MAX == 255
+ typedef unsigned char png_byte;
+#else
+# error "libpng requires 8-bit bytes"
+#endif
+
+#if INT_MIN == -32768 && INT_MAX == 32767
+ typedef int png_int_16;
+#elif SHRT_MIN == -32768 && SHRT_MAX == 32767
+ typedef short png_int_16;
+#else
+# error "libpng requires a signed 16-bit type"
+#endif
+
+#if UINT_MAX == 65535
+ typedef unsigned int png_uint_16;
+#elif USHRT_MAX == 65535
+ typedef unsigned short png_uint_16;
+#else
+# error "libpng requires an unsigned 16-bit type"
+#endif
+
+#if INT_MIN < -2147483646 && INT_MAX > 2147483646
+ typedef int png_int_32;
+#elif LONG_MIN < -2147483646 && LONG_MAX > 2147483646
+ typedef long int png_int_32;
+#else
+# error "libpng requires a signed 32-bit (or more) type"
+#endif
+
+#if UINT_MAX > 4294967294
+ typedef unsigned int png_uint_32;
+#elif ULONG_MAX > 4294967294
+ typedef unsigned long int png_uint_32;
+#else
+# error "libpng requires an unsigned 32-bit (or more) type"
+#endif
+
+/* Prior to 1.6.0 it was possible to disable the use of size_t, 1.6.0, however,
+ * requires an ISOC90 compiler and relies on consistent behavior of sizeof.
+ */
+typedef size_t png_size_t;
+typedef ptrdiff_t png_ptrdiff_t;
+
+/* libpng needs to know the maximum value of 'size_t' and this controls the
+ * definition of png_alloc_size_t, below. This maximum value of size_t limits
+ * but does not control the maximum allocations the library makes - there is
+ * direct application control of this through png_set_user_limits().
+ */
+#ifndef PNG_SMALL_SIZE_T
+ /* Compiler specific tests for systems where size_t is known to be less than
+ * 32 bits (some of these systems may no longer work because of the lack of
+ * 'far' support; see above.)
+ */
+# if (defined(__TURBOC__) && !defined(__FLAT__)) ||\
+ (defined(_MSC_VER) && defined(MAXSEG_64K))
+# define PNG_SMALL_SIZE_T
+# endif
+#endif
+
+/* png_alloc_size_t is guaranteed to be no smaller than png_size_t, and no
+ * smaller than png_uint_32. Casts from png_size_t or png_uint_32 to
+ * png_alloc_size_t are not necessary; in fact, it is recommended not to use
+ * them at all so that the compiler can complain when something turns out to be
+ * problematic.
+ *
+ * Casts in the other direction (from png_alloc_size_t to png_size_t or
+ * png_uint_32) should be explicitly applied; however, we do not expect to
+ * encounter practical situations that require such conversions.
+ *
+ * PNG_SMALL_SIZE_T must be defined if the maximum value of size_t is less than
