diff options
Diffstat (limited to 'image/decoders/nsBMPDecoder.cpp')
| -rw-r--r-- | image/decoders/nsBMPDecoder.cpp | 45 |
1 files changed, 32 insertions, 13 deletions
diff --git a/image/decoders/nsBMPDecoder.cpp b/image/decoders/nsBMPDecoder.cpp index fc79c223d..b93eb42b6 100644 --- a/image/decoders/nsBMPDecoder.cpp +++ b/image/decoders/nsBMPDecoder.cpp @@ -66,6 +66,17 @@ // compression, then instead of treating the pixel data as 0RGB it is treated // as ARGB, but only if one or more of the A values are non-zero. // +// Clipboard variants. +// - It's the BMP format used for BMP images captured from the clipboard. +// - It is missing the file header, containing the BM signature and the data +// offset. Instead the data begins after the header. +// - If it uses BITFIELDS compression, then there is always an additional 12 +// bytes of data after the header that must be read. In WinBMPv4+, the masks +// are supposed to be included in the header size, which are the values we use +// for decoding purposes, but there is additional three masks following the +// header which must be skipped to get to the pixel data. +// +// // OS/2 VERSIONS OF THE BMP FORMAT // ------------------------------- // OS2-BMPv1. @@ -168,10 +179,12 @@ static mozilla::LazyLogModule sBMPLog("BMPDecoder"); // The length of the mBIHSize field in the info header. static const uint32_t BIHSIZE_FIELD_LENGTH = 4; -nsBMPDecoder::nsBMPDecoder(RasterImage* aImage, State aState, size_t aLength) +nsBMPDecoder::nsBMPDecoder(RasterImage* aImage, State aState, size_t aLength, + bool aForClipboard) : Decoder(aImage) , mLexer(Transition::To(aState, aLength), Transition::TerminateSuccess()) , mIsWithinICO(false) + , mIsForClipboard(aForClipboard) , mMayHaveTransparency(false) , mDoesHaveTransparency(false) , mNumColors(0) @@ -188,14 +201,16 @@ nsBMPDecoder::nsBMPDecoder(RasterImage* aImage, State aState, size_t aLength) // Constructor for normal BMP files or from the clipboard. nsBMPDecoder::nsBMPDecoder(RasterImage* aImage, bool aForClipboard) : nsBMPDecoder(aImage, - aForClipboard ? State::CLIPBOARD_HEADER : State::FILE_HEADER, - aForClipboard ? BIHSIZE_FIELD_LENGTH : FILE_HEADER_LENGTH) + aForClipboard ? State::INFO_HEADER_SIZE : State::FILE_HEADER, + aForClipboard ? BIHSIZE_FIELD_LENGTH : FILE_HEADER_LENGTH, + aForClipboard) { } // Constructor used for WinBMPv3-ICO files, which lack a file header. nsBMPDecoder::nsBMPDecoder(RasterImage* aImage, uint32_t aDataOffset) - : nsBMPDecoder(aImage, State::INFO_HEADER_SIZE, BIHSIZE_FIELD_LENGTH) + : nsBMPDecoder(aImage, State::INFO_HEADER_SIZE, BIHSIZE_FIELD_LENGTH, + /* aForClipboard */ false) { SetIsWithinICO(); @@ -457,7 +472,6 @@ nsBMPDecoder::DoDecode(SourceBufferIterator& aIterator, IResumable* aOnResume) [=](State aState, const char* aData, size_t aLength) { switch (aState) { case State::FILE_HEADER: return ReadFileHeader(aData, aLength); - case State::CLIPBOARD_HEADER: return ReadClipboardHeader(aData, aLength); case State::INFO_HEADER_SIZE: return ReadInfoHeaderSize(aData, aLength); case State::INFO_HEADER_REST: return ReadInfoHeaderRest(aData, aLength); case State::BITFIELDS: return ReadBitfields(aData, aLength); @@ -491,14 +505,6 @@ nsBMPDecoder::ReadFileHeader(const char* aData, size_t aLength) return Transition::To(State::INFO_HEADER_SIZE, BIHSIZE_FIELD_LENGTH); } -LexerTransition<nsBMPDecoder::State> -nsBMPDecoder::ReadClipboardHeader(const char* aData, size_t aLength) -{ - // With the clipboard, the data offset is the header length. - mH.mDataOffset = LittleEndian::readUint32(aData); - return ReadInfoHeaderSize(aData, aLength); -} - // We read the info header in two steps: (a) read the mBIHSize field to // determine how long the header is; (b) read the rest of the header. LexerTransition<nsBMPDecoder::State> @@ -609,6 +615,13 @@ nsBMPDecoder::ReadInfoHeaderRest(const char* aData, size_t aLength) // Bitfields are present in the info header, so we can read them // immediately. mBitFields.ReadFromHeader(aData + 36, /* aReadAlpha = */ true); + + // If this came from the clipboard, then we know that even if the header + // explicitly includes the bitfield masks, we need to add an additional + // offset for the start of the RGB data. + if (mIsForClipboard) { + mH.mDataOffset += BitFields::LENGTH; + } } else { // Bitfields are present after the info header, so we will read them in // ReadBitfields(). @@ -723,6 +736,12 @@ nsBMPDecoder::ReadColorTable(const char* aData, size_t aLength) aData += mBytesPerColor; } + // If we are decoding a BMP from the clipboard, we did not know the data + // offset in advance. It is defined as just after the header and color table. + if (mIsForClipboard) { + mH.mDataOffset += mPreGapLength; + } + // We know how many bytes we've read so far (mPreGapLength) and we know the // offset of the pixel data (mH.mDataOffset), so we can determine the length // of the gap (possibly zero) between the color table and the pixel data. |