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// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef ICO_DECODER_H_
#define ICO_DECODER_H_
#include "BMPImageReader.h"
#include "PNGImageDecoder.h"
namespace WebCore {
// This class decodes the ICO and CUR image formats.
class ICOImageDecoder : public BMPImageReader
{
public:
// See comments on |m_preferredIconSize| below.
ICOImageDecoder(const IntSize& preferredIconSize)
: m_preferredIconSize(preferredIconSize)
, m_imageType(UNKNOWN)
{
m_andMaskState = NOT_YET_DECODED;
}
virtual String filenameExtension() const { return "ico"; }
// BMPImageReader
virtual void decodeImage(SharedBuffer* data);
virtual RGBA32Buffer* frameBufferAtIndex(size_t index);
// ImageDecoder
virtual bool isSizeAvailable() const;
virtual IntSize size() const;
private:
enum ImageType {
UNKNOWN,
BMP,
PNG,
};
// These are based on the Windows ICONDIR and ICONDIRENTRY structs, but
// with unnecessary entries removed.
struct IconDirectory {
uint16_t idCount;
};
struct IconDirectoryEntry {
uint16_t bWidth; // 16 bits so we can represent 256 as 256, not 0
uint16_t bHeight; // "
uint16_t wBitCount;
uint32_t dwImageOffset;
};
// Processes the ICONDIR at the beginning of the data. Returns true if the
// directory could be decoded.
bool processDirectory(SharedBuffer* data);
// Processes the ICONDIRENTRY records after the directory. Keeps the
// "best" entry as the one we'll decode. Returns true if the entries could
// be decoded.
bool processDirectoryEntries(SharedBuffer* data);
// Reads and returns a directory entry from the current offset into |data|.
IconDirectoryEntry readDirectoryEntry(SharedBuffer* data);
// Returns true if |entry| is a preferable icon entry to m_dirEntry.
// Larger sizes, or greater bitdepths at the same size, are preferable.
bool isBetterEntry(const IconDirectoryEntry& entry) const;
// Called when the image to be decoded is a PNG rather than a BMP.
// Instantiates a PNGImageDecoder, decodes the image, and copies the
// results locally.
void decodePNG(SharedBuffer* data);
// The entry size we should prefer. If this is empty, we choose the
// largest available size. If no entries of the desired size are
// available, we pick the next larger size.
IntSize m_preferredIconSize;
// The headers for the ICO.
IconDirectory m_directory;
IconDirectoryEntry m_dirEntry;
// The PNG decoder, if we need to use one.
PNGImageDecoder m_pngDecoder;
// What kind of image data is stored at the entry we're decoding.
ImageType m_imageType;
};
}
#endif
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