| /* |
| * Copyright (c) 2008, 2009, Google Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are |
| * met: |
| * |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following disclaimer |
| * in the documentation and/or other materials provided with the |
| * distribution. |
| * * Neither the name of Google Inc. nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include "third_party/blink/renderer/platform/fonts/vdmx_parser.h" |
| |
| #include "base/macros.h" |
| #include "base/sys_byteorder.h" |
| #include "third_party/blink/renderer/platform/wtf/allocator/allocator.h" |
| |
| #include <stdlib.h> |
| #include <string.h> |
| |
| namespace blink { |
| namespace { |
| |
| // Buffer helper class |
| // |
| // This class perform some trival buffer operations while checking for |
| // out-of-bounds errors. As a family they return false if anything is amiss, |
| // updating the current offset otherwise. |
| class Buffer { |
| STACK_ALLOCATED(); |
| |
| public: |
| Buffer(const uint8_t* buffer, size_t length) |
| : buffer_(buffer), length_(length), offset_(0) {} |
| |
| bool skip(size_t numBytes) { |
| if (offset_ + numBytes > length_) |
| return false; |
| offset_ += numBytes; |
| return true; |
| } |
| |
| bool ReadU8(uint8_t* value) { |
| if (offset_ + sizeof(uint8_t) > length_) |
| return false; |
| *value = buffer_[offset_]; |
| offset_ += sizeof(uint8_t); |
| return true; |
| } |
| |
| bool ReadU16(uint16_t* value) { |
| if (offset_ + sizeof(uint16_t) > length_) |
| return false; |
| memcpy(value, buffer_ + offset_, sizeof(uint16_t)); |
| *value = base::NetToHost16(*value); |
| offset_ += sizeof(uint16_t); |
| return true; |
| } |
| |
| bool ReadS16(int16_t* value) { |
| return ReadU16(reinterpret_cast<uint16_t*>(value)); |
| } |
| |
| size_t Offset() const { return offset_; } |
| |
| void SetOffset(size_t newoffset) { offset_ = newoffset; } |
| |
| private: |
| const uint8_t* const buffer_; |
| const size_t length_; |
| size_t offset_; |
| |
| DISALLOW_COPY_AND_ASSIGN(Buffer); |
| }; |
| |
| } // namespace |
| |
| // VDMX parsing code. |
| // |
| // VDMX tables are found in some TrueType/OpenType fonts and contain |
| // ascender/descender overrides for certain (usually small) sizes. This is |
| // needed in order to match font metrics on Windows. |
| // |
| // Freetype does not parse these tables so we do so here. |
| |
| // Parse a TrueType VDMX table. |
| // yMax: (output) the ascender value from the table |
| // yMin: (output) the descender value from the table (negative!) |
| // vdmx: the table bytes |
| // vdmxLength: length of @vdmx, in bytes |
| // targetPixelSize: the pixel size of the font (e.g. 16) |
| // |
| // Returns true iff a suitable match are found. Otherwise, *yMax and *yMin are |
| // untouched. size_t must be 32-bits to avoid overflow. |
| // |
| // See http://www.microsoft.com/opentype/otspec/vdmx.htm |
| bool ParseVDMX(int* y_max, |
| int* y_min, |
| const uint8_t* vdmx, |
| size_t vdmx_length, |
| unsigned target_pixel_size) { |
| Buffer buf(vdmx, vdmx_length); |
| |
| // We ignore the version. Future tables should be backwards compatible with |
| // this layout. |
| uint16_t num_ratios; |
| if (!buf.skip(4) || !buf.ReadU16(&num_ratios)) |
| return false; |
| |
| // Now we have two tables. Firstly we have @numRatios Ratio records, then a |
| // matching array of @numRatios offsets. We save the offset of the beginning |
| // of this second table. |
| // |
| // Range 6 <= x <= 262146 |
| size_t offset_table_offset = |
| buf.Offset() + 4 /* sizeof struct ratio */ * num_ratios; |
| |
| unsigned desired_ratio = 0xffffffff; |
| // We read 4 bytes per record, so the offset range is |
| // 6 <= x <= 524286 |
| for (unsigned i = 0; i < num_ratios; ++i) { |
| uint8_t x_ratio, y_ratio1, y_ratio2; |
| |
| if (!buf.skip(1) || !buf.ReadU8(&x_ratio) || !buf.ReadU8(&y_ratio1) || |
| !buf.ReadU8(&y_ratio2)) |
| return false; |
| |
| // This either covers 1:1, or this is the default entry (0, 0, 0) |
| if ((x_ratio == 1 && y_ratio1 <= 1 && y_ratio2 >= 1) || |
| (x_ratio == 0 && y_ratio1 == 0 && y_ratio2 == 0)) { |
| desired_ratio = i; |
| break; |
| } |
| } |
| |
| if (desired_ratio == 0xffffffff) // no ratio found |
| return false; |
| |
| // Range 10 <= x <= 393216 |
| buf.SetOffset(offset_table_offset + sizeof(uint16_t) * desired_ratio); |
| |
| // Now we read from the offset table to get the offset of another array |
| uint16_t group_offset; |
| if (!buf.ReadU16(&group_offset)) |
| return false; |
| // Range 0 <= x <= 65535 |
| buf.SetOffset(group_offset); |
| |
| uint16_t num_records; |
| if (!buf.ReadU16(&num_records) || !buf.skip(sizeof(uint16_t))) |
| return false; |
| |
| // We read 6 bytes per record, so the offset range is |
| // 4 <= x <= 458749 |
| for (unsigned i = 0; i < num_records; ++i) { |
| uint16_t pixel_size; |
| if (!buf.ReadU16(&pixel_size)) |
| return false; |
| // the entries are sorted, so we can abort early if need be |
| if (pixel_size > target_pixel_size) |
| return false; |
| |
| if (pixel_size == target_pixel_size) { |
| int16_t temp_y_max, temp_y_min; |
| if (!buf.ReadS16(&temp_y_max) || !buf.ReadS16(&temp_y_min)) |
| return false; |
| *y_min = temp_y_min; |
| *y_max = temp_y_max; |
| return true; |
| } |
| if (!buf.skip(2 * sizeof(int16_t))) |
| return false; |
| } |
| |
| return false; |
| } |
| |
| } // namespace blink |