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/*
* Copyright 2014 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkColorPriv.h"
#include "SkImageDecoder.h"
#include "SkPixelRef.h"
#include "SkScaledBitmapSampler.h"
#include "SkStream.h"
#include "SkStreamPriv.h"
#include "SkTypes.h"
#include "ktx.h"
#include "etc1.h"
/////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////////////
// KTX Image decoder
// ---
// KTX is a general texture data storage file format ratified by the Khronos Group. As an
// overview, a KTX file contains all of the appropriate values needed to fully specify a
// texture in an OpenGL application, including the use of compressed data.
//
// This decoder is meant to be used with an SkDiscardablePixelRef so that GPU backends
// can sniff the data before creating a texture. If they encounter a compressed format
// that they understand, they can then upload the data directly to the GPU. Otherwise,
// they will decode the data into a format that Skia supports.
class SkKTXImageDecoder : public SkImageDecoder {
public:
SkKTXImageDecoder() { }
Format getFormat() const override {
return kKTX_Format;
}
protected:
Result onDecode(SkStream* stream, SkBitmap* bm, Mode) override;
private:
typedef SkImageDecoder INHERITED;
};
SkImageDecoder::Result SkKTXImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) {
// TODO: Implement SkStream::copyToData() that's cheap for memory and file streams
SkAutoDataUnref data(SkCopyStreamToData(stream));
if (NULL == data) {
return kFailure;
}
SkKTXFile ktxFile(data);
if (!ktxFile.valid()) {
return kFailure;
}
const unsigned short width = ktxFile.width();
const unsigned short height = ktxFile.height();
// Set a flag if our source is premultiplied alpha
const SkString premulKey("KTXPremultipliedAlpha");
const bool bSrcIsPremul = ktxFile.getValueForKey(premulKey) == SkString("True");
// Setup the sampler...
SkScaledBitmapSampler sampler(width, height, this->getSampleSize());
// Determine the alpha of the bitmap...
SkAlphaType alphaType = kOpaque_SkAlphaType;
if (ktxFile.isRGBA8()) {
if (this->getRequireUnpremultipliedColors()) {
alphaType = kUnpremul_SkAlphaType;
// If the client wants unpremul colors and we only have
// premul, then we cannot honor their wish.
if (bSrcIsPremul) {
return kFailure;
}
} else {
alphaType = kPremul_SkAlphaType;
}
}
// Search through the compressed formats to see if the KTX file is holding
// compressed data
bool ktxIsCompressed = false;
SkTextureCompressor::Format ktxCompressedFormat;
for (int i = 0; i < SkTextureCompressor::kFormatCnt; ++i) {
SkTextureCompressor::Format fmt = static_cast<SkTextureCompressor::Format>(i);
if (ktxFile.isCompressedFormat(fmt)) {
ktxIsCompressed = true;
ktxCompressedFormat = fmt;
break;
}
}
// If the compressed format is a grayscale image, then setup the bitmap properly...
bool isCompressedAlpha = ktxIsCompressed &&
((SkTextureCompressor::kLATC_Format == ktxCompressedFormat) ||
(SkTextureCompressor::kR11_EAC_Format == ktxCompressedFormat));
// Set the image dimensions and underlying pixel type.
if (isCompressedAlpha) {
const int w = sampler.scaledWidth();
const int h = sampler.scaledHeight();
bm->setInfo(SkImageInfo::MakeA8(w, h));
} else {
const int w = sampler.scaledWidth();
const int h = sampler.scaledHeight();
bm->setInfo(SkImageInfo::MakeN32(w, h, alphaType));
}
if (SkImageDecoder::kDecodeBounds_Mode == mode) {
return kSuccess;
}
// If we've made it this far, then we know how to grok the data.
if (!this->allocPixelRef(bm, NULL)) {
return kFailure;
}
// Lock the pixels, since we're about to write to them...
SkAutoLockPixels alp(*bm);
if (isCompressedAlpha) {
if (!sampler.begin(bm, SkScaledBitmapSampler::kGray, *this)) {
return kFailure;
}
// Alpha data is only a single byte per pixel.
int nPixels = width * height;
SkAutoMalloc outRGBData(nPixels);
uint8_t *outRGBDataPtr = reinterpret_cast<uint8_t *>(outRGBData.get());
// Decode the compressed format
const uint8_t *buf = reinterpret_cast<const uint8_t *>(ktxFile.pixelData());
if (!SkTextureCompressor::DecompressBufferFromFormat(
outRGBDataPtr, width, buf, width, height, ktxCompressedFormat)) {
return kFailure;
}
// Set each of the pixels...
const int srcRowBytes = width;
const int dstHeight = sampler.scaledHeight();
const uint8_t *srcRow = reinterpret_cast<uint8_t *>(outRGBDataPtr);
srcRow += sampler.srcY0() * srcRowBytes;
for (int y = 0; y < dstHeight; ++y) {
sampler.next(srcRow);
srcRow += sampler.srcDY() * srcRowBytes;
}
return kSuccess;
} else if (ktxFile.isCompressedFormat(SkTextureCompressor::kETC1_Format)) {
if (!sampler.begin(bm, SkScaledBitmapSampler::kRGB, *this)) {
return kFailure;
}
// ETC1 Data is encoded as RGB pixels, so we should extract it as such
int nPixels = width * height;
SkAutoMalloc outRGBData(nPixels * 3);
uint8_t *outRGBDataPtr = reinterpret_cast<uint8_t *>(outRGBData.get());
// Decode ETC1
const uint8_t *buf = reinterpret_cast<const uint8_t *>(ktxFile.pixelData());
if (!SkTextureCompressor::DecompressBufferFromFormat(
outRGBDataPtr, width*3, buf, width, height, SkTextureCompressor::kETC1_Format)) {
return kFailure;
}
// Set each of the pixels...
const int srcRowBytes = width * 3;
const int dstHeight = sampler.scaledHeight();
const uint8_t *srcRow = reinterpret_cast<uint8_t *>(outRGBDataPtr);
srcRow += sampler.srcY0() * srcRowBytes;
for (int y = 0; y < dstHeight; ++y) {
sampler.next(srcRow);
srcRow += sampler.srcDY() * srcRowBytes;
}
return kSuccess;
} else if (ktxFile.isRGB8()) {
// Uncompressed RGB data (without alpha)
if (!sampler.begin(bm, SkScaledBitmapSampler::kRGB, *this)) {
return kFailure;
}
// Just need to read RGB pixels
const int srcRowBytes = width * 3;
const int dstHeight = sampler.scaledHeight();
const uint8_t *srcRow = reinterpret_cast<const uint8_t *>(ktxFile.pixelData());
srcRow += sampler.srcY0() * srcRowBytes;
for (int y = 0; y < dstHeight; ++y) {
sampler.next(srcRow);
srcRow += sampler.srcDY() * srcRowBytes;
}
return kSuccess;
} else if (ktxFile.isRGBA8()) {
// Uncompressed RGBA data
// If we know that the image contains premultiplied alpha, then
// we need to turn off the premultiplier
SkScaledBitmapSampler::Options opts (*this);
if (bSrcIsPremul) {
SkASSERT(bm->alphaType() == kPremul_SkAlphaType);
SkASSERT(!this->getRequireUnpremultipliedColors());
opts.fPremultiplyAlpha = false;
}
if (!sampler.begin(bm, SkScaledBitmapSampler::kRGBA, opts)) {
return kFailure;
}
// Just need to read RGBA pixels
const int srcRowBytes = width * 4;
const int dstHeight = sampler.scaledHeight();
const uint8_t *srcRow = reinterpret_cast<const uint8_t *>(ktxFile.pixelData());
srcRow += sampler.srcY0() * srcRowBytes;
for (int y = 0; y < dstHeight; ++y) {
sampler.next(srcRow);
srcRow += sampler.srcDY() * srcRowBytes;
}
return kSuccess;
}
return kFailure;
}
///////////////////////////////////////////////////////////////////////////////
// KTX Image Encoder
//
// This encoder takes a best guess at how to encode the bitmap passed to it. If
// there is an installed discardable pixel ref with existing PKM data, then we
// will repurpose the existing ETC1 data into a KTX file. If the data contains
// KTX data, then we simply return a copy of the same data. For all other files,
// the underlying KTX library tries to do its best to encode the appropriate
// data specified by the bitmap based on the config. (i.e. kAlpha8_Config will
// be represented as a full resolution 8-bit image dump with the appropriate
// OpenGL defines in the header).
class SkKTXImageEncoder : public SkImageEncoder {
protected:
bool onEncode(SkWStream* stream, const SkBitmap& bm, int quality) override;
private:
virtual bool encodePKM(SkWStream* stream, const SkData *data);
typedef SkImageEncoder INHERITED;
};
bool SkKTXImageEncoder::onEncode(SkWStream* stream, const SkBitmap& bitmap, int) {
if (!bitmap.pixelRef()) {
return false;
}
SkAutoDataUnref data(bitmap.pixelRef()->refEncodedData());
// Is this even encoded data?
if (data) {
const uint8_t *bytes = data->bytes();
if (etc1_pkm_is_valid(bytes)) {
return this->encodePKM(stream, data);
}
// Is it a KTX file??
if (SkKTXFile::is_ktx(bytes)) {
return stream->write(bytes, data->size());
}
// If it's neither a KTX nor a PKM, then we need to
// get at the actual pixels, so fall through and decompress...
}
return SkKTXFile::WriteBitmapToKTX(stream, bitmap);
}
bool SkKTXImageEncoder::encodePKM(SkWStream* stream, const SkData *data) {
const uint8_t* bytes = data->bytes();
SkASSERT(etc1_pkm_is_valid(bytes));
etc1_uint32 width = etc1_pkm_get_width(bytes);
etc1_uint32 height = etc1_pkm_get_height(bytes);
// ETC1 Data is stored as compressed 4x4 pixel blocks, so we must make sure
// that our dimensions are valid.
if (width == 0 || (width & 3) != 0 || height == 0 || (height & 3) != 0) {
return false;
}
// Advance pointer to etc1 data.
bytes += ETC_PKM_HEADER_SIZE;
return SkKTXFile::WriteETC1ToKTX(stream, bytes, width, height);
}
/////////////////////////////////////////////////////////////////////////////////////////
DEFINE_DECODER_CREATOR(KTXImageDecoder);
DEFINE_ENCODER_CREATOR(KTXImageEncoder);
/////////////////////////////////////////////////////////////////////////////////////////
static SkImageDecoder* sk_libktx_dfactory(SkStreamRewindable* stream) {
if (SkKTXFile::is_ktx(stream)) {
return SkNEW(SkKTXImageDecoder);
}
return NULL;
}
static SkImageDecoder::Format get_format_ktx(SkStreamRewindable* stream) {
if (SkKTXFile::is_ktx(stream)) {
return SkImageDecoder::kKTX_Format;
}
return SkImageDecoder::kUnknown_Format;
}
SkImageEncoder* sk_libktx_efactory(SkImageEncoder::Type t) {
return (SkImageEncoder::kKTX_Type == t) ? SkNEW(SkKTXImageEncoder) : NULL;
}
static SkImageDecoder_DecodeReg gReg(sk_libktx_dfactory);
static SkImageDecoder_FormatReg gFormatReg(get_format_ktx);
static SkImageEncoder_EncodeReg gEReg(sk_libktx_efactory);