bmpimagedecoder.cpp

linux下开源浏览器WebKit的源码,市面上的很多商用浏览器都是移植自WebKit

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 * this software without specific prior written permission.
 * 
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 */

#include "config.h"
#include "BMPImageDecoder.h"

namespace WebCore {

// Number of bits in .BMP used to store the file header (doesn't match
// "sizeof(BMPImageDecoder::BitmapFileHeader)" since we omit some fields and
// don't pack).
static const size_t sizeOfFileHeader = 14;

void BMPImageDecoder::decodeImage(SharedBuffer* data)
{
    // Read and process file header.
    if ((m_decodedOffset < sizeOfFileHeader) && !processFileHeader(data))
        return;

    // Decode BMP.
    decodeBMP(data);
}

bool BMPImageDecoder::processFileHeader(SharedBuffer* data)
{
    // Read file header.
    ASSERT(!m_decodedOffset);
    if (data->size() < sizeOfFileHeader)
        return false;
    const uint16_t fileType =
        (data->data()[0] << 8) | static_cast<uint8_t>(data->data()[1]);
    m_imgDataOffset = readUint32(data, 10);
    m_decodedOffset = m_headerOffset = sizeOfFileHeader;

    // See if this is a bitmap filetype we understand.
    enum {
        BMAP = 'BM',
        // The following additional OS/2 2.x header values (see
        // http://www.fileformat.info/format/os2bmp/egff.htm ) aren't widely
        // decoded, and are unlikely to be in much use.
        /*
        ICON = 'IC',
        POINTER = 'PT',
        COLORICON = 'CI',
        COLORPOINTER = 'CP',
        BITMAPARRAY = 'BA',
        */
    };
    if (fileType != BMAP)
        m_failed = true;

    return !m_failed;
}

} // namespace WebCore