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      1 /*
      2  * Copyright (c) 2008, 2009, Google 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 are
      6  * met:
      7  *
      8  *     * Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *     * Redistributions in binary form must reproduce the above
     11  * copyright notice, this list of conditions and the following disclaimer
     12  * in the documentation and/or other materials provided with the
     13  * distribution.
     14  *     * Neither the name of Google Inc. nor the names of its
     15  * contributors may be used to endorse or promote products derived from
     16  * this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #ifndef ICOImageDecoder_h
     32 #define ICOImageDecoder_h
     33 
     34 #include "BMPImageReader.h"
     35 
     36 namespace WebCore {
     37 
     38     class PNGImageDecoder;
     39 
     40     // This class decodes the ICO and CUR image formats.
     41     class ICOImageDecoder : public ImageDecoder {
     42     public:
     43         ICOImageDecoder();
     44 
     45         // ImageDecoder
     46         virtual String filenameExtension() const { return "ico"; }
     47         virtual void setData(SharedBuffer*, bool allDataReceived);
     48         virtual bool isSizeAvailable();
     49         virtual IntSize size() const;
     50         virtual IntSize frameSizeAtIndex(size_t) const;
     51         virtual bool setSize(unsigned width, unsigned height);
     52         virtual size_t frameCount();
     53         virtual RGBA32Buffer* frameBufferAtIndex(size_t);
     54 
     55     private:
     56         enum ImageType {
     57             Unknown,
     58             BMP,
     59             PNG,
     60         };
     61 
     62         struct IconDirectoryEntry {
     63             IntSize m_size;
     64             uint16_t m_bitCount;
     65             uint32_t m_imageOffset;
     66         };
     67 
     68         // Returns true if |a| is a preferable icon entry to |b|.
     69         // Larger sizes, or greater bitdepths at the same size, are preferable.
     70         static bool compareEntries(const IconDirectoryEntry& a,
     71                                    const IconDirectoryEntry& b);
     72 
     73         inline uint16_t readUint16(int offset) const
     74         {
     75             return BMPImageReader::readUint16(m_data.get(),
     76                                               m_decodedOffset + offset);
     77         }
     78 
     79         inline uint32_t readUint32(int offset) const
     80         {
     81             return BMPImageReader::readUint32(m_data.get(),
     82                                               m_decodedOffset + offset);
     83         }
     84 
     85         // If the desired PNGImageDecoder exists, gives it the appropriate data.
     86         void setDataForPNGDecoderAtIndex(size_t);
     87 
     88         // Decodes the entry at |index|.  If |onlySize| is true, stops decoding
     89         // after calculating the image size.  If decoding fails but there is no
     90         // more data coming, sets the "decode failure" flag.
     91         //
     92         // NOTE: If the desired entry is a PNG, this doesn't actually trigger
     93         // decoding, it merely ensures the decoder is created and ready to
     94         // decode.  The caller will then call a function on the PNGImageDecoder
     95         // that actually triggers decoding.
     96         void decodeWithCheckForDataEnded(size_t index, bool onlySize);
     97 
     98         // Decodes the directory and directory entries at the beginning of the
     99         // data, and initializes members.  Returns true if all decoding
    100         // succeeded.  Once this returns true, all entries' sizes are known.
    101         bool decodeDirectory();
    102 
    103         // Decodes the specified entry.
    104         bool decodeAtIndex(size_t);
    105 
    106         // Processes the ICONDIR at the beginning of the data.  Returns true if
    107         // the directory could be decoded.
    108         bool processDirectory();
    109 
    110         // Processes the ICONDIRENTRY records after the directory.  Keeps the
    111         // "best" entry as the one we'll decode.  Returns true if the entries
    112         // could be decoded.
    113         bool processDirectoryEntries();
    114 
    115         // Reads and returns a directory entry from the current offset into
    116         // |data|.
    117         IconDirectoryEntry readDirectoryEntry();
    118 
    119         // Determines whether the desired entry is a BMP or PNG.  Returns true
    120         // if the type could be determined.
    121         ImageType imageTypeAtIndex(size_t);
    122 
    123         // True if we've seen all the data.
    124         bool m_allDataReceived;
    125 
    126         // An index into |m_data| representing how much we've already decoded.
    127         // Note that this only tracks data _this_ class decodes; once the
    128         // BMPImageReader takes over this will not be updated further.
    129         size_t m_decodedOffset;
    130 
    131         // The headers for the ICO.
    132         typedef Vector<IconDirectoryEntry> IconDirectoryEntries;
    133         IconDirectoryEntries m_dirEntries;
    134 
    135         // The image decoders for the various frames.
    136         typedef Vector<OwnPtr<BMPImageReader> > BMPReaders;
    137         BMPReaders m_bmpReaders;
    138         typedef Vector<OwnPtr<PNGImageDecoder> > PNGDecoders;
    139         PNGDecoders m_pngDecoders;
    140 
    141         // Valid only while a BMPImageReader is decoding, this holds the size
    142         // for the particular entry being decoded.
    143         IntSize m_frameSize;
    144     };
    145 
    146 } // namespace WebCore
    147 
    148 #endif
    149