Source/core/platform/image-decoders/gif/GIFImageDecoder.h

/*
 * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef GIFImageDecoder_h
#define GIFImageDecoder_h

#include "core/platform/image-decoders/ImageDecoder.h"
#include "wtf/OwnPtr.h"

class GIFImageReader;

namespace WebCore {

    // This class decodes the GIF image format.
    class GIFImageDecoder : public ImageDecoder {
    public:
        GIFImageDecoder(ImageSource::AlphaOption, ImageSource::GammaAndColorProfileOption, const IntSize&);
        virtual ~GIFImageDecoder();

        enum GIFParseQuery { GIFSizeQuery, GIFFrameCountQuery };

        // ImageDecoder
        virtual String filenameExtension() const OVERRIDE { return "gif"; }
        virtual void setData(SharedBuffer* data, bool allDataReceived) OVERRIDE;
        virtual bool isSizeAvailable() OVERRIDE;
        virtual size_t frameCount() OVERRIDE;
        virtual int repetitionCount() const OVERRIDE;
        virtual ImageFrame* frameBufferAtIndex(size_t) OVERRIDE;
        virtual bool frameIsCompleteAtIndex(size_t) const OVERRIDE;
        virtual float frameDurationAtIndex(size_t) const OVERRIDE;
        virtual size_t clearCacheExceptFrame(size_t) OVERRIDE;
        // CAUTION: setFailed() deletes |m_reader|.  Be careful to avoid
        // accessing deleted memory, especially when calling this from inside
        // GIFImageReader!
        virtual bool setFailed() OVERRIDE;

        // Callbacks from the GIF reader.
        bool haveDecodedRow(size_t frameIndex, const Vector<unsigned char>& rowBuffer, size_t width, size_t rowNumber, unsigned repeatCount, bool writeTransparentPixels);
        bool frameComplete(size_t frameIndex);

        // For testing.
        bool parseCompleted() const;

    private:
        virtual void clearFrameBuffer(size_t frameIndex) OVERRIDE;

        // Parses as much as is needed to answer the query, ignoring bitmap
        // data. If parsing fails, sets the "decode failure" flag.
        void parse(GIFParseQuery);

        // Decodes bitmap data of the frame. Depending on the disposal method
        // of prior frames, also decodes all required prior frames. If decoding
        // fails, sets the "decode failure" flag.
        void decode(size_t frameIndex);

        // Called to initialize the frame buffer with the given index, based on
        // the previous frame's disposal method. Returns true on success. On
        // failure, this will mark the image as failed.
        bool initFrameBuffer(size_t frameIndex);

        bool m_currentBufferSawAlpha;
        mutable int m_repetitionCount;
        OwnPtr<GIFImageReader> m_reader;
    };

} // namespace WebCore

#endif