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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.
*/
#ifndef SkPngCodec_DEFINED
#define SkPngCodec_DEFINED
#include "SkCodec.h"
#include "SkColorSpaceXform.h"
#include "SkColorTable.h"
#include "SkPngChunkReader.h"
#include "SkEncodedImageFormat.h"
#include "SkImageInfo.h"
#include "SkRefCnt.h"
#include "SkSwizzler.h"
// FIXME (scroggo): GOOGLE3 is currently using an outdated version of libpng,
// so we need to work around the lack of the method png_process_data_pause.
// This code will be unnecessary once we update GOOGLE3. It would make more
// sense to condition this on the version of libpng being used, but we do not
// know that here because png.h is only included by the cpp file.
#define SK_GOOGLE3_PNG_HACK
class SkStream;
class SkPngCodec : public SkCodec {
public:
static bool IsPng(const char*, size_t);
// Assume IsPng was called and returned true.
static SkCodec* NewFromStream(SkStream*, SkPngChunkReader* = NULL);
virtual ~SkPngCodec();
protected:
// We hold the png_ptr and info_ptr as voidp to avoid having to include png.h
// or forward declare their types here. voidp auto-casts to the real pointer types.
struct voidp {
voidp(void* ptr) : fPtr(ptr) {}
template <typename T>
operator T*() const { return (T*)fPtr; }
explicit operator bool() const { return fPtr != nullptr; }
void* fPtr;
};
SkPngCodec(const SkEncodedInfo&, const SkImageInfo&, SkStream*, SkPngChunkReader*,
void* png_ptr, void* info_ptr, int bitDepth);
Result onGetPixels(const SkImageInfo&, void*, size_t, const Options&, SkPMColor*, int*, int*)
override;
SkEncodedImageFormat onGetEncodedFormat() const override { return SkEncodedImageFormat::kPNG; }
bool onRewind() override;
uint64_t onGetFillValue(const SkImageInfo&) const override;
SkSampler* getSampler(bool createIfNecessary) override;
void applyXformRow(void* dst, const void* src);
voidp png_ptr() { return fPng_ptr; }
voidp info_ptr() { return fInfo_ptr; }
SkSwizzler* swizzler() { return fSwizzler.get(); }
// Initialize variables used by applyXformRow.
void initializeXformParams();
/**
* Pass available input to libpng to process it.
*
* libpng will call any relevant callbacks installed. This will continue decoding
* until it reaches the end of the file, or until a callback tells libpng to stop.
*/
void processData();
#ifdef SK_GOOGLE3_PNG_HACK
// In libpng 1.2.56, png_process_data_pause does not exist, so when we wanted to
// read the header, we may have read too far. In that case, we need to delete the
// png_ptr and info_ptr and recreate them. This method does that (and attaches the
// chunk reader.
bool rereadHeaderIfNecessary();
// This method sets up the new png_ptr/info_ptr (created in rereadHeaderIfNecessary)
// the way we set up the old one the first time in AutoCleanPng.decodeBounds's callback.
void rereadInfoCallback();
#endif
Result onStartIncrementalDecode(const SkImageInfo& dstInfo, void* pixels, size_t rowBytes,
const SkCodec::Options&,
SkPMColor* ctable, int* ctableCount) override;
Result onIncrementalDecode(int*) override;
sk_sp<SkPngChunkReader> fPngChunkReader;
voidp fPng_ptr;
voidp fInfo_ptr;
// These are stored here so they can be used both by normal decoding and scanline decoding.
sk_sp<SkColorTable> fColorTable; // May be unpremul.
std::unique_ptr<SkSwizzler> fSwizzler;
SkAutoTMalloc<uint8_t> fStorage;
void* fColorXformSrcRow;
const int fBitDepth;
private:
enum XformMode {
// Requires only a swizzle pass.
kSwizzleOnly_XformMode,
// Requires only a color xform pass.
kColorOnly_XformMode,
// Requires a swizzle and a color xform.
kSwizzleColor_XformMode,
};
bool createColorTable(const SkImageInfo& dstInfo, int* ctableCount);
// Helper to set up swizzler, color xforms, and color table. Also calls png_read_update_info.
bool initializeXforms(const SkImageInfo& dstInfo, const Options&, SkPMColor* colorPtr,
int* colorCount);
void initializeSwizzler(const SkImageInfo& dstInfo, const Options&, bool skipFormatConversion);
void allocateStorage(const SkImageInfo& dstInfo);
void destroyReadStruct();
virtual Result decodeAllRows(void* dst, size_t rowBytes, int* rowsDecoded) = 0;
virtual void setRange(int firstRow, int lastRow, void* dst, size_t rowBytes) = 0;
virtual Result decode(int* rowsDecoded) = 0;
XformMode fXformMode;
SkColorSpaceXform::ColorFormat fXformColorFormat;
SkAlphaType fXformAlphaType;
int fXformWidth;
#ifdef SK_GOOGLE3_PNG_HACK
bool fNeedsToRereadHeader;
#endif
typedef SkCodec INHERITED;
};
#endif // SkPngCodec_DEFINED
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