1/*
2 * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#ifndef GIFImageDecoder_h
27#define GIFImageDecoder_h
28
29#include "ImageDecoder.h"
30#include <wtf/OwnPtr.h>
31
32class GIFImageReader;
33
34namespace WebCore {
35
36    // This class decodes the GIF image format.
37    class GIFImageDecoder : public ImageDecoder {
38    public:
39        GIFImageDecoder(ImageSource::AlphaOption, ImageSource::GammaAndColorProfileOption);
40        virtual ~GIFImageDecoder();
41
42        enum GIFQuery { GIFFullQuery, GIFSizeQuery, GIFFrameCountQuery };
43
44        // ImageDecoder
45        virtual String filenameExtension() const { return "gif"; }
46        virtual void setData(SharedBuffer* data, bool allDataReceived);
47        virtual bool isSizeAvailable();
48        virtual bool setSize(unsigned width, unsigned height);
49        virtual size_t frameCount();
50        virtual int repetitionCount() const;
51        virtual ImageFrame* frameBufferAtIndex(size_t index);
52        // CAUTION: setFailed() deletes |m_reader|.  Be careful to avoid
53        // accessing deleted memory, especially when calling this from inside
54        // GIFImageReader!
55        virtual bool setFailed();
56        virtual void clearFrameBufferCache(size_t clearBeforeFrame);
57
58        // Callbacks from the GIF reader.
59        bool haveDecodedRow(unsigned frameIndex, const Vector<unsigned char>& rowBuffer, size_t width, size_t rowNumber, unsigned repeatCount, bool writeTransparentPixels);
60        bool frameComplete(unsigned frameIndex, unsigned frameDuration, ImageFrame::FrameDisposalMethod disposalMethod);
61        void gifComplete();
62
63    private:
64        // If the query is GIFFullQuery, decodes the image up to (but not
65        // including) |haltAtFrame|.  Otherwise, decodes as much as is needed to
66        // answer the query, ignoring bitmap data.  If decoding fails but there
67        // is no more data coming, sets the "decode failure" flag.
68        void decode(unsigned haltAtFrame, GIFQuery);
69
70        // Called to initialize the frame buffer with the given index, based on
71        // the previous frame's disposal method. Returns true on success. On
72        // failure, this will mark the image as failed.
73        bool initFrameBuffer(unsigned frameIndex);
74
75        bool m_currentBufferSawAlpha;
76        mutable int m_repetitionCount;
77        OwnPtr<GIFImageReader> m_reader;
78    };
79
80} // namespace WebCore
81
82#endif
83