/**
* Write an integer value to a stream in little-endian order.
*/
static void write_int_to_buffer(uint32_t val, SkWStream* out) {
val = SkEndian_SwapLE32(val);
for (size_t byte = 0; byte < 4; ++byte) {
out->write8((uint8_t)(val & 0xff));
val = val >> 8;
}
}
/**
* Write an integer value into a bytebuffer in little-endian order.
*/
static void write_int_to_buffer(int val, char* buf) {
val = SkEndian_SwapLE32(val);
for (int byte=0; byte<4; byte++) {
*buf++ = (char)(val & 0xff);
val = val >> 8;
}
}
static bool is_astc(SkStreamRewindable* stream) {
// Read the ASTC header and make sure it's valid.
uint32_t magic;
if (stream->read((void*)&magic, 4) != 4) {
return false;
}
return kASTCMagicNumber == SkEndian_SwapLE32(magic);
}
SkImageDecoder::Result SkASTCImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) {
SkAutoMalloc autoMal;
const size_t length = SkCopyStreamToStorage(&autoMal, stream);
if (0 == length) {
return kFailure;
}
unsigned char* buf = (unsigned char*)autoMal.get();
// Make sure that the magic header is there...
SkASSERT(SkEndian_SwapLE32(*(reinterpret_cast<uint32_t*>(buf))) == kASTCMagicNumber);
// Advance past the magic header
buf += 4;
const int blockDimX = buf[0];
const int blockDimY = buf[1];
const int blockDimZ = buf[2];
if (1 != blockDimZ) {
// We don't support decoding 3D
return kFailure;
}
// Choose the proper ASTC format
SkTextureCompressor::Format astcFormat;
if (4 == blockDimX && 4 == blockDimY) {
astcFormat = SkTextureCompressor::kASTC_4x4_Format;
} else if (5 == blockDimX && 4 == blockDimY) {
astcFormat = SkTextureCompressor::kASTC_5x4_Format;
} else if (5 == blockDimX && 5 == blockDimY) {
astcFormat = SkTextureCompressor::kASTC_5x5_Format;
} else if (6 == blockDimX && 5 == blockDimY) {
astcFormat = SkTextureCompressor::kASTC_6x5_Format;
} else if (6 == blockDimX && 6 == blockDimY) {
astcFormat = SkTextureCompressor::kASTC_6x6_Format;
} else if (8 == blockDimX && 5 == blockDimY) {
astcFormat = SkTextureCompressor::kASTC_8x5_Format;
} else if (8 == blockDimX && 6 == blockDimY) {
astcFormat = SkTextureCompressor::kASTC_8x6_Format;
} else if (8 == blockDimX && 8 == blockDimY) {
astcFormat = SkTextureCompressor::kASTC_8x8_Format;
} else if (10 == blockDimX && 5 == blockDimY) {
astcFormat = SkTextureCompressor::kASTC_10x5_Format;
} else if (10 == blockDimX && 6 == blockDimY) {
astcFormat = SkTextureCompressor::kASTC_10x6_Format;
} else if (10 == blockDimX && 8 == blockDimY) {
astcFormat = SkTextureCompressor::kASTC_10x8_Format;
} else if (10 == blockDimX && 10 == blockDimY) {
astcFormat = SkTextureCompressor::kASTC_10x10_Format;
} else if (12 == blockDimX && 10 == blockDimY) {
astcFormat = SkTextureCompressor::kASTC_12x10_Format;
} else if (12 == blockDimX && 12 == blockDimY) {
astcFormat = SkTextureCompressor::kASTC_12x12_Format;
} else {
// We don't support any other block dimensions..
return kFailure;
}
// Advance buf past the block dimensions
buf += 3;
// Read the width/height/depth from the buffer...
const int width = read_24bit(buf);
const int height = read_24bit(buf + 3);
const int depth = read_24bit(buf + 6);
if (1 != depth) {
// We don't support decoding 3D.
return kFailure;
}
// Advance the buffer past the image dimensions
buf += 9;
// Setup the sampler...
SkScaledBitmapSampler sampler(width, height, this->getSampleSize());
// Determine the alpha of the bitmap...
SkAlphaType alphaType = kOpaque_SkAlphaType;
if (this->getRequireUnpremultipliedColors()) {
alphaType = kUnpremul_SkAlphaType;
} else {
alphaType = kPremul_SkAlphaType;
}
// Set the config...
bm->setInfo(SkImageInfo::MakeN32(sampler.scaledWidth(), sampler.scaledHeight(), alphaType));
if (SkImageDecoder::kDecodeBounds_Mode == mode) {
return kSuccess;
}
if (!this->allocPixelRef(bm, NULL)) {
return kFailure;
}
// Lock the pixels, since we're about to write to them...
SkAutoLockPixels alp(*bm);
if (!sampler.begin(bm, SkScaledBitmapSampler::kRGBA, *this)) {
return kFailure;
}
// ASTC Data is encoded as RGBA pixels, so we should extract it as such
int nPixels = width * height;
SkAutoMalloc outRGBAData(nPixels * 4);
uint8_t *outRGBADataPtr = reinterpret_cast<uint8_t *>(outRGBAData.get());
// Decode ASTC
if (!SkTextureCompressor::DecompressBufferFromFormat(
outRGBADataPtr, width*4, buf, width, height, astcFormat)) {
return kFailure;
}
// Set each of the pixels...
const int srcRowBytes = width * 4;
const int dstHeight = sampler.scaledHeight();
const uint8_t *srcRow = reinterpret_cast<uint8_t *>(outRGBADataPtr);
srcRow += sampler.srcY0() * srcRowBytes;
for (int y = 0; y < dstHeight; ++y) {
sampler.next(srcRow);
srcRow += sampler.srcDY() * srcRowBytes;
}
return kSuccess;
}
