// A BMP inside of an ICO has *2 height because of the AND mask
// that follows the actual bitmap. The BMP shouldn't know about
// this difference though.
bool
nsICODecoder::FixBitmapHeight(PRInt8 *bih)
{
// Get the height from the BMP file information header
PRInt32 height;
memcpy(&height, bih + 8, sizeof(height));
height = LITTLE_TO_NATIVE32(height);
// The bitmap height is by definition * 2 what it should be to account for
// the 'AND mask'. It is * 2 even if the `AND mask` is not present.
height /= 2;
if (height > 256) {
return false;
}
// We should always trust the height from the bitmap itself instead of
// the ICO height. So fix the ICO height.
if (height == 256) {
mDirEntry.mHeight = 0;
} else {
mDirEntry.mHeight = (PRInt8)height;
}
// Fix the BMP height in the BIH so that the BMP decoder can work properly
height = NATIVE32_TO_LITTLE(height);
memcpy(bih + 8, &height, sizeof(height));
return true;
}
PRInt32
nsICODecoder::ExtractBIHSizeFromBitmap(PRInt8 *bih)
{
PRInt32 headerSize;
memcpy(&headerSize, bih, sizeof(headerSize));
headerSize = LITTLE_TO_NATIVE32(headerSize);
return headerSize;
}
// The BMP information header's bits per pixel should be trusted
// more than what we have. Usually the ICO's BPP is set to 0
PRInt32
nsICODecoder::ExtractBPPFromBitmap(PRInt8 *bih)
{
PRInt32 bitsPerPixel;
memcpy(&bitsPerPixel, bih + 14, sizeof(bitsPerPixel));
bitsPerPixel = LITTLE_TO_NATIVE32(bitsPerPixel);
return bitsPerPixel;
}
int32_t
nsICODecoder::ExtractBIHSizeFromBitmap(int8_t *bih)
{
int32_t headerSize;
memcpy(&headerSize, bih, sizeof(headerSize));
headerSize = LITTLE_TO_NATIVE32(headerSize);
return headerSize;
}
// We should always trust the contained resource for the width
// information over our own information.
bool
nsICODecoder::FixBitmapWidth(PRInt8 *bih)
{
// Get the width from the BMP file information header
PRInt32 width;
memcpy(&width, bih + 4, sizeof(width));
width = LITTLE_TO_NATIVE32(width);
if (width > 256) {
return false;
}
// We should always trust the width from the bitmap itself instead of
// the ICO width.
if (width == 256) {
mDirEntry.mWidth = 0;
} else {
mDirEntry.mWidth = (PRInt8)width;
}
return true;
}
