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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
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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(ImageSource::AlphaOption, ImageSource::GammaAndColorProfileOption);
     44         virtual ~ICOImageDecoder();
     45 
     46         // ImageDecoder
     47         virtual String filenameExtension() const { return "ico"; }
     48         virtual void setData(SharedBuffer*, bool allDataReceived);
     49         virtual bool isSizeAvailable();
     50         virtual IntSize size() const;
     51         virtual IntSize frameSizeAtIndex(size_t) const;
     52         virtual bool setSize(unsigned width, unsigned height);
     53         virtual size_t frameCount();
     54         virtual ImageFrame* frameBufferAtIndex(size_t);
     55         // CAUTION: setFailed() deletes all readers and decoders.  Be careful to
     56         // avoid accessing deleted memory, especially when calling this from
     57         // inside BMPImageReader!
     58         virtual bool setFailed();
     59 
     60     private:
     61         enum ImageType {
     62             Unknown,
     63             BMP,
     64             PNG,
     65         };
     66 
     67         struct IconDirectoryEntry {
     68             IntSize m_size;
     69             uint16_t m_bitCount;
     70             uint32_t m_imageOffset;
     71         };
     72 
     73         // Returns true if |a| is a preferable icon entry to |b|.
     74         // Larger sizes, or greater bitdepths at the same size, are preferable.
     75         static bool compareEntries(const IconDirectoryEntry& a, const IconDirectoryEntry& b);
     76 
     77         inline uint16_t readUint16(int offset) const
     78         {
     79             return BMPImageReader::readUint16(m_data.get(), m_decodedOffset + offset);
     80         }
     81 
     82         inline uint32_t readUint32(int offset) const
     83         {
     84             return BMPImageReader::readUint32(m_data.get(), m_decodedOffset + offset);
     85         }
     86 
     87         // If the desired PNGImageDecoder exists, gives it the appropriate data.
     88         void setDataForPNGDecoderAtIndex(size_t);
     89 
     90         // Decodes the entry at |index|.  If |onlySize| is true, stops decoding
     91         // after calculating the image size.  If decoding fails but there is no
     92         // more data coming, sets the "decode failure" flag.
     93         void decode(size_t index, bool onlySize);
     94 
     95         // Decodes the directory and directory entries at the beginning of the
     96         // data, and initializes members.  Returns true if all decoding
     97         // succeeded.  Once this returns true, all entries' sizes are known.
     98         bool decodeDirectory();
     99 
    100         // Decodes the specified entry.
    101         bool decodeAtIndex(size_t);
    102 
    103         // Processes the ICONDIR at the beginning of the data.  Returns true if
    104         // the directory could be decoded.
    105         bool processDirectory();
    106 
    107         // Processes the ICONDIRENTRY records after the directory.  Keeps the
    108         // "best" entry as the one we'll decode.  Returns true if the entries
    109         // could be decoded.
    110         bool processDirectoryEntries();
    111 
    112         // Reads and returns a directory entry from the current offset into
    113         // |data|.
    114         IconDirectoryEntry readDirectoryEntry();
    115 
    116         // Determines whether the desired entry is a BMP or PNG.  Returns true
    117         // if the type could be determined.
    118         ImageType imageTypeAtIndex(size_t);
    119 
    120         // An index into |m_data| representing how much we've already decoded.
    121         // Note that this only tracks data _this_ class decodes; once the
    122         // BMPImageReader takes over this will not be updated further.
    123         size_t m_decodedOffset;
    124 
    125         // The headers for the ICO.
    126         typedef Vector<IconDirectoryEntry> IconDirectoryEntries;
    127         IconDirectoryEntries m_dirEntries;
    128 
    129         // The image decoders for the various frames.
    130         typedef Vector<OwnPtr<BMPImageReader> > BMPReaders;
    131         BMPReaders m_bmpReaders;
    132         typedef Vector<OwnPtr<PNGImageDecoder> > PNGDecoders;
    133         PNGDecoders m_pngDecoders;
    134 
    135         // Valid only while a BMPImageReader is decoding, this holds the size
    136         // for the particular entry being decoded.
    137         IntSize m_frameSize;
    138     };
    139 
    140 } // namespace WebCore
    141 
    142 #endif
    143