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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 "SkImageInfo.h"
#include "SkJpegDecoderMgr.h"
#include "SkJpegUtility_codec.h"
#include "SkStream.h"
extern "C" {
#include "jpeglib.h"
}
/*
*
* This class implements the decoding for jpeg images
*
*/
class SkJpegCodec : public SkCodec {
public:
/*
* Checks the start of the stream to see if the image is a jpeg
* Does not take ownership of the stream
*/
static bool IsJpeg(SkStream*);
/*
* 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*) override;
SkEncodedFormat onGetEncodedFormat() const override {
return kJPEG_SkEncodedFormat;
}
SkScanlineDecoder* onGetScanlineDecoder(const SkImageInfo& dstInfo, const Options& options,
SkPMColor ctable[], int* ctableCount) 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 NULL,
* codecOut will be set to a new SkJpegCodec.
*
* @param decoderMgrOut
* If this returns true, and codecOut was NULL,
* decoderMgrOut must be non-NULL 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 srcInfo contains the source width and height
* @param stream the encoded image data
* @param decoderMgr holds decompress struct, src manager, and error manager
* takes ownership
*/
SkJpegCodec(const SkImageInfo& srcInfo, SkStream* stream, JpegDecoderMgr* decoderMgr);
/*
* Explicit destructor is used to ensure that the scanline decoder is deleted
* before the decode manager.
*/
~SkJpegCodec() override;
/*
* Handles rewinding the input stream if it is necessary
*/
bool handleRewind();
/*
* Checks if we can scale to the requested dimensions and scales the dimensions
* if possible
*/
bool scaleToDimensions(uint32_t width, uint32_t height);
/*
* Create the swizzler based on the encoded format
*/
void initializeSwizzler(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes,
const Options& options);
SkAutoTDelete<JpegDecoderMgr> fDecoderMgr;
SkAutoTDelete<SkSwizzler> fSwizzler;
size_t fSrcRowBytes;
friend class SkJpegScanlineDecoder;
typedef SkCodec INHERITED;
};
#endif
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