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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 SkJpegCodec_DEFINED
#define SkJpegCodec_DEFINED
#include "SkCodec.h"
#include "SkColorSpace.h"
#include "SkColorSpaceXform.h"
#include "SkImageInfo.h"
#include "SkSwizzler.h"
#include "SkStream.h"
#include "SkTemplates.h"
class JpegDecoderMgr;
/*
*
* This class implements the decoding for jpeg images
*
*/
class SkJpegCodec : public SkCodec {
public:
static bool IsJpeg(const void*, size_t);
/*
* Assumes IsJpeg was called and returned true
* Creates a jpeg decoder
* Takes ownership of the stream
*/
static SkCodec* NewFromStream(SkStream*);
protected:
/*
* Recommend a set of destination dimensions given a requested scale
*/
SkISize onGetScaledDimensions(float desiredScale) const override;
/*
* Initiates the jpeg decode
*/
Result onGetPixels(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes, const Options&,
SkPMColor*, int*, int*) override;
bool onQueryYUV8(SkYUVSizeInfo* sizeInfo, SkYUVColorSpace* colorSpace) const override;
Result onGetYUV8Planes(const SkYUVSizeInfo& sizeInfo, void* planes[3]) override;
SkEncodedImageFormat onGetEncodedFormat() const override {
return SkEncodedImageFormat::kJPEG;
}
bool onRewind() override;
bool onDimensionsSupported(const SkISize&) override;
private:
/*
* Read enough of the stream to initialize the SkJpegCodec.
* Returns a bool representing success or failure.
*
* @param codecOut
* If this returns true, and codecOut was not nullptr,
* codecOut will be set to a new SkJpegCodec.
*
* @param decoderMgrOut
* If this returns true, and codecOut was nullptr,
* decoderMgrOut must be non-nullptr and decoderMgrOut will be set to a new
* JpegDecoderMgr pointer.
*
* @param stream
* Deleted on failure.
* codecOut will take ownership of it in the case where we created a codec.
* Ownership is unchanged when we set decoderMgrOut.
*
*/
static bool ReadHeader(SkStream* stream, SkCodec** codecOut,
JpegDecoderMgr** decoderMgrOut);
/*
* Creates an instance of the decoder
* Called only by NewFromStream
*
* @param info contains properties of the encoded data
* @param stream the encoded image data
* @param decoderMgr holds decompress struct, src manager, and error manager
* takes ownership
*/
SkJpegCodec(int width, int height, const SkEncodedInfo& info, SkStream* stream,
JpegDecoderMgr* decoderMgr, sk_sp<SkColorSpace> colorSpace, Origin origin);
/*
* Checks if the conversion between the input image and the requested output
* image has been implemented.
*
* Sets the output color space.
*/
bool setOutputColorSpace(const SkImageInfo& dst);
void initializeSwizzler(const SkImageInfo& dstInfo, const Options& options);
void allocateStorage(const SkImageInfo& dstInfo);
int readRows(const SkImageInfo& dstInfo, void* dst, size_t rowBytes, int count);
/*
* Scanline decoding.
*/
SkSampler* getSampler(bool createIfNecessary) override;
Result onStartScanlineDecode(const SkImageInfo& dstInfo, const Options& options,
SkPMColor ctable[], int* ctableCount) override;
int onGetScanlines(void* dst, int count, size_t rowBytes) override;
bool onSkipScanlines(int count) override;
std::unique_ptr<JpegDecoderMgr> fDecoderMgr;
// We will save the state of the decompress struct after reading the header.
// This allows us to safely call onGetScaledDimensions() at any time.
const int fReadyState;
SkAutoTMalloc<uint8_t> fStorage;
uint8_t* fSwizzleSrcRow;
uint32_t* fColorXformSrcRow;
// libjpeg-turbo provides some subsetting. In the case that libjpeg-turbo
// cannot take the exact the subset that we need, we will use the swizzler
// to further subset the output from libjpeg-turbo.
SkIRect fSwizzlerSubset;
std::unique_ptr<SkSwizzler> fSwizzler;
typedef SkCodec INHERITED;
};
#endif
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