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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 "SkImageInfo.h"
#include "gif_lib.h"
/*
*
* This class implements the decoding for gif images
*
*/
class SkGifCodec : public SkCodec {
public:
/*
* Checks the start of the stream to see if the image is a gif
*/
static bool IsGif(SkStream*);
/*
* Assumes IsGif was called and returned true
* Creates a gif decoder
* Reads enough of the stream to determine the image format
*/
static SkCodec* NewFromStream(SkStream*);
protected:
/*
* Read enough of the stream to initialize the SkGifCodec.
* Returns a bool representing success or failure.
*
* @param codecOut
* If it returned true, and codecOut was not nullptr,
* codecOut will be set to a new SkGifCodec.
*
* @param gifOut
* If it returned true, and codecOut was nullptr,
* gifOut must be non-nullptr and gifOut will be set to a new
* GifFileType 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 returned a gifOut.
*
*/
static bool ReadHeader(SkStream* stream, SkCodec** codecOut, GifFileType** gifOut);
/*
* Initiates the gif decode
*/
Result onGetPixels(const SkImageInfo&, void*, size_t, const Options&,
SkPMColor*, int32_t*) override;
SkEncodedFormat onGetEncodedFormat() const override {
return kGIF_SkEncodedFormat;
}
bool onRewind() override;
private:
/*
* This function cleans up the gif object after the decode completes
* It is used in a SkAutoTCallIProc template
*/
static void CloseGif(GifFileType* gif);
/*
* Frees any extension data used in the decode
* Used in a SkAutoTCallVProc
*/
static void FreeExtension(SavedImage* image);
/*
* Creates an instance of the decoder
* Called only by NewFromStream
*
* @param srcInfo contains the source width and height
* @param stream the stream of image data
* @param gif pointer to library type that manages gif decode
* takes ownership
*/
SkGifCodec(const SkImageInfo& srcInfo, SkStream* stream, GifFileType* gif);
SkAutoTCallVProc<GifFileType, CloseGif> fGif; // owned
typedef SkCodec INHERITED;
};
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