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/*
* Copyright 2015 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkCodec.h"
#include "SkColorTable.h"
#include "SkEncodedFormat.h"
#include "SkImageInfo.h"
#include "SkRefCnt.h"
#include "SkSwizzler.h"
#ifdef SKIA_PNG_PREFIXED
// this must proceed png.h
#include "pngprefix.h"
#endif
#include "png.h"
class SkScanlineDecoder;
class SkStream;
class SkPngCodec : public SkCodec {
public:
static bool IsPng(SkStream*);
// Assume IsPng was called and returned true.
static SkCodec* NewFromStream(SkStream*);
static SkScanlineDecoder* NewSDFromStream(SkStream*);
virtual ~SkPngCodec();
protected:
Result onGetPixels(const SkImageInfo&, void*, size_t, const Options&, SkPMColor*, int*)
override;
SkEncodedFormat onGetEncodedFormat() const override { return kPNG_SkEncodedFormat; }
bool onRewind() override;
bool onReallyHasAlpha() const final;
// Helper to set up swizzler and color table. Also calls png_read_update_info.
Result initializeSwizzler(const SkImageInfo& requestedInfo, const Options&,
SkPMColor*, int* ctableCount);
SkPngCodec(const SkImageInfo&, SkStream*, png_structp, png_infop, int, int);
png_structp png_ptr() { return fPng_ptr; }
SkSwizzler* swizzler() { return fSwizzler; }
SkSwizzler::SrcConfig srcConfig() const { return fSrcConfig; }
int numberPasses() const { return fNumberPasses; }
enum AlphaState {
// This class has done no decoding, or threw away its knowledge (in
// scanline decodes).
kUnknown_AlphaState,
// This class found the image (possibly partial, in the case of a
// scanline decode) to be opaque.
kOpaque_AlphaState,
// Ths class found the image to have alpha.
kHasAlpha_AlphaState,
};
virtual AlphaState alphaInScanlineDecode() const = 0;
private:
png_structp fPng_ptr;
png_infop fInfo_ptr;
// These are stored here so they can be used both by normal decoding and scanline decoding.
SkAutoTUnref<SkColorTable> fColorTable; // May be unpremul.
SkAutoTDelete<SkSwizzler> fSwizzler;
SkSwizzler::SrcConfig fSrcConfig;
const int fNumberPasses;
int fBitDepth;
AlphaState fAlphaState;
bool decodePalette(bool premultiply, int* ctableCount);
void destroyReadStruct();
typedef SkCodec INHERITED;
};
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