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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 "SkEndian.h"
#include "SkColorPriv.h"
#include "SkImageDecoder.h"
#include "SkScaledBitmapSampler.h"
#include "SkStream.h"
#include "SkStreamPriv.h"
#include "SkTypes.h"
#include "SkTextureCompressor.h"
class SkASTCImageDecoder : public SkImageDecoder {
public:
SkASTCImageDecoder() { }
Format getFormat() const override {
return kASTC_Format;
}
protected:
Result onDecode(SkStream* stream, SkBitmap* bm, Mode) override;
private:
typedef SkImageDecoder INHERITED;
};
/////////////////////////////////////////////////////////////////////////////////////////
static const uint32_t kASTCMagicNumber = 0x5CA1AB13;
static inline int read_24bit(const uint8_t* buf) {
// Assume everything is little endian...
return
static_cast<int>(buf[0]) |
(static_cast<int>(buf[1]) << 8) |
(static_cast<int>(buf[2]) << 16);
}
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;
}
/////////////////////////////////////////////////////////////////////////////////////////
DEFINE_DECODER_CREATOR(ASTCImageDecoder);
/////////////////////////////////////////////////////////////////////////////////////////
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);
}
static SkImageDecoder* sk_libastc_dfactory(SkStreamRewindable* stream) {
if (is_astc(stream)) {
return SkNEW(SkASTCImageDecoder);
}
return NULL;
}
static SkImageDecoder_DecodeReg gReg(sk_libastc_dfactory);
static SkImageDecoder::Format get_format_astc(SkStreamRewindable* stream) {
if (is_astc(stream)) {
return SkImageDecoder::kASTC_Format;
}
return SkImageDecoder::kUnknown_Format;
}
static SkImageDecoder_FormatReg gFormatReg(get_format_astc);
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