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Diffstat (limited to 'image/decoders/nsBMPDecoder.cpp')
| -rw-r--r-- | image/decoders/nsBMPDecoder.cpp | 1067 |
1 files changed, 1067 insertions, 0 deletions
diff --git a/image/decoders/nsBMPDecoder.cpp b/image/decoders/nsBMPDecoder.cpp new file mode 100644 index 0000000000..1f0449e4e6 --- /dev/null +++ b/image/decoders/nsBMPDecoder.cpp @@ -0,0 +1,1067 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +// This is a cross-platform BMP Decoder, which should work everywhere, +// including big-endian machines like the PowerPC. +// +// BMP is a format that has been extended multiple times. To understand the +// decoder you need to understand this history. The summary of the history +// below was determined from the following documents. +// +// - http://www.fileformat.info/format/bmp/egff.htm +// - http://www.fileformat.info/format/os2bmp/egff.htm +// - http://fileformats.archiveteam.org/wiki/BMP +// - http://fileformats.archiveteam.org/wiki/OS/2_BMP +// - https://en.wikipedia.org/wiki/BMP_file_format +// - https://upload.wikimedia.org/wikipedia/commons/c/c4/BMPfileFormat.png +// +// WINDOWS VERSIONS OF THE BMP FORMAT +// ---------------------------------- +// WinBMPv1. +// - This version is no longer used and can be ignored. +// +// WinBMPv2. +// - First is a 14 byte file header that includes: the magic number ("BM"), +// file size, and offset to the pixel data (|mDataOffset|). +// - Next is a 12 byte info header which includes: the info header size +// (mBIHSize), width, height, number of color planes, and bits-per-pixel +// (|mBpp|) which must be 1, 4, 8 or 24. +// - Next is the semi-optional color table, which has length 2^|mBpp| and has 3 +// bytes per value (BGR). The color table is required if |mBpp| is 1, 4, or 8. +// - Next is an optional gap. +// - Next is the pixel data, which is pointed to by |mDataOffset|. +// +// WinBMPv3. This is the most widely used version. +// - It changed the info header to 40 bytes by taking the WinBMPv2 info +// header, enlargening its width and height fields, and adding more fields +// including: a compression type (|mCompression|) and number of colors +// (|mNumColors|). +// - The semi-optional color table is now 4 bytes per value (BGR0), and its +// length is |mNumColors|, or 2^|mBpp| if |mNumColors| is zero. +// - |mCompression| can be RGB (i.e. no compression), RLE4 (if |mBpp|==4) or +// RLE8 (if |mBpp|==8) values. +// +// WinBMPv3-NT. A variant of WinBMPv3. +// - It did not change the info header layout from WinBMPv3. +// - |mBpp| can now be 16 or 32, in which case |mCompression| can be RGB or the +// new BITFIELDS value; in the latter case an additional 12 bytes of color +// bitfields follow the info header. +// +// WinBMPv4. +// - It extended the info header to 108 bytes, including the 12 bytes of color +// mask data from WinBMPv3-NT, plus alpha mask data, and also color-space and +// gamma correction fields. +// +// WinBMPv5. +// - It extended the info header to 124 bytes, adding color profile data. +// - It also added an optional color profile table after the pixel data (and +// another optional gap). +// +// WinBMPv3-ICO. This is a variant of WinBMPv3. +// - It's the BMP format used for BMP images within ICO files. +// - The only difference with WinBMPv3 is that if an image is 32bpp and has no +// 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. +// +// OS/2 VERSIONS OF THE BMP FORMAT +// ------------------------------- +// OS2-BMPv1. +// - Almost identical to WinBMPv2; the differences are basically ignorable. +// +// OS2-BMPv2. +// - Similar to WinBMPv3. +// - The info header is 64 bytes but can be reduced to as little as 16; any +// omitted fields are treated as zero. The first 40 bytes of these fields are +// nearly identical to the WinBMPv3 info header; the remaining 24 bytes are +// different. +// - Also adds compression types "Huffman 1D" and "RLE24", which we don't +// support. +// - We treat OS2-BMPv2 files as if they are WinBMPv3 (i.e. ignore the extra 24 +// bytes in the info header), which in practice is good enough. + +#include "ImageLogging.h" +#include "nsBMPDecoder.h" + +#include <stdlib.h> + +#include "mozilla/Attributes.h" +#include "mozilla/EndianUtils.h" +#include "mozilla/Likely.h" + +#include "nsIInputStream.h" +#include "RasterImage.h" +#include <algorithm> + +using namespace mozilla::gfx; + +namespace mozilla { +namespace image { +namespace bmp { + +struct Compression { + enum { + RGB = 0, + RLE8 = 1, + RLE4 = 2, + BITFIELDS = 3 + }; +}; + +// RLE escape codes and constants. +struct RLE { + enum { + ESCAPE = 0, + ESCAPE_EOL = 0, + ESCAPE_EOF = 1, + ESCAPE_DELTA = 2, + + SEGMENT_LENGTH = 2, + DELTA_LENGTH = 2 + }; +}; + +} // namespace bmp + +using namespace bmp; + +/// Sets the pixel data in aDecoded to the given values. +/// @param aDecoded pointer to pixel to be set, will be incremented to point to +/// the next pixel. +static void +SetPixel(uint32_t*& aDecoded, uint8_t aRed, uint8_t aGreen, + uint8_t aBlue, uint8_t aAlpha = 0xFF) +{ + *aDecoded++ = gfxPackedPixel(aAlpha, aRed, aGreen, aBlue); +} + +static void +SetPixel(uint32_t*& aDecoded, uint8_t idx, + const UniquePtr<ColorTableEntry[]>& aColors) +{ + SetPixel(aDecoded, + aColors[idx].mRed, aColors[idx].mGreen, aColors[idx].mBlue); +} + +/// Sets two (or one if aCount = 1) pixels +/// @param aDecoded where the data is stored. Will be moved 4 resp 8 bytes +/// depending on whether one or two pixels are written. +/// @param aData The values for the two pixels +/// @param aCount Current count. Is decremented by one or two. +static void +Set4BitPixel(uint32_t*& aDecoded, uint8_t aData, uint32_t& aCount, + const UniquePtr<ColorTableEntry[]>& aColors) +{ + uint8_t idx = aData >> 4; + SetPixel(aDecoded, idx, aColors); + if (--aCount > 0) { + idx = aData & 0xF; + SetPixel(aDecoded, idx, aColors); + --aCount; + } +} + +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) + : Decoder(aImage) + , mLexer(Transition::To(aState, aLength), Transition::TerminateSuccess()) + , mIsWithinICO(false) + , mMayHaveTransparency(false) + , mDoesHaveTransparency(false) + , mNumColors(0) + , mColors(nullptr) + , mBytesPerColor(0) + , mPreGapLength(0) + , mPixelRowSize(0) + , mCurrentRow(0) + , mCurrentPos(0) + , mAbsoluteModeNumPixels(0) +{ +} + +// Constructor for normal BMP files. +nsBMPDecoder::nsBMPDecoder(RasterImage* aImage) + : nsBMPDecoder(aImage, State::FILE_HEADER, FILE_HEADER_LENGTH) +{ +} + +// 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) +{ + SetIsWithinICO(); + + // Even though the file header isn't present in this case, the dataOffset + // field is set as if it is, and so we must increment mPreGapLength + // accordingly. + mPreGapLength += FILE_HEADER_LENGTH; + + // This is the one piece of data we normally get from a BMP file header, so + // it must be provided via an argument. + mH.mDataOffset = aDataOffset; +} + +nsBMPDecoder::~nsBMPDecoder() +{ +} + +// Obtains the size of the compressed image resource. +int32_t +nsBMPDecoder::GetCompressedImageSize() const +{ + // In the RGB case mImageSize might not be set, so compute it manually. + MOZ_ASSERT(mPixelRowSize != 0); + return mH.mCompression == Compression::RGB + ? mPixelRowSize * AbsoluteHeight() + : mH.mImageSize; +} + +nsresult +nsBMPDecoder::BeforeFinishInternal() +{ + if (!IsMetadataDecode() && !mImageData) { + return NS_ERROR_FAILURE; // No image; something went wrong. + } + + return NS_OK; +} + +nsresult +nsBMPDecoder::FinishInternal() +{ + // We shouldn't be called in error cases. + MOZ_ASSERT(!HasError(), "Can't call FinishInternal on error!"); + + // We should never make multiple frames. + MOZ_ASSERT(GetFrameCount() <= 1, "Multiple BMP frames?"); + + // Send notifications if appropriate. + if (!IsMetadataDecode() && HasSize()) { + + // We should have image data. + MOZ_ASSERT(mImageData); + + // If it was truncated, fill in the missing pixels as black. + while (mCurrentRow > 0) { + uint32_t* dst = RowBuffer(); + while (mCurrentPos < mH.mWidth) { + SetPixel(dst, 0, 0, 0); + mCurrentPos++; + } + mCurrentPos = 0; + FinishRow(); + } + + // Invalidate. + nsIntRect r(0, 0, mH.mWidth, AbsoluteHeight()); + PostInvalidation(r); + + MOZ_ASSERT_IF(mDoesHaveTransparency, mMayHaveTransparency); + + // We have transparency if we either detected some in the image itself + // (i.e., |mDoesHaveTransparency| is true) or we're in an ICO, which could + // mean we have an AND mask that provides transparency (i.e., |mIsWithinICO| + // is true). + // XXX(seth): We can tell when we create the decoder if the AND mask is + // present, so we could be more precise about this. + const Opacity opacity = mDoesHaveTransparency || mIsWithinICO + ? Opacity::SOME_TRANSPARENCY + : Opacity::FULLY_OPAQUE; + + PostFrameStop(opacity); + PostDecodeDone(); + } + + return NS_OK; +} + +// ---------------------------------------- +// Actual Data Processing +// ---------------------------------------- + +void +BitFields::Value::Set(uint32_t aMask) +{ + mMask = aMask; + + // Handle this exceptional case first. The chosen values don't matter + // (because a mask of zero will always give a value of zero) except that + // mBitWidth: + // - shouldn't be zero, because that would cause an infinite loop in Get(); + // - shouldn't be 5 or 8, because that could cause a false positive match in + // IsR5G5B5() or IsR8G8B8(). + if (mMask == 0x0) { + mRightShift = 0; + mBitWidth = 1; + return; + } + + // Find the rightmost 1. + uint8_t i; + for (i = 0; i < 32; i++) { + if (mMask & (1 << i)) { + break; + } + } + mRightShift = i; + + // Now find the leftmost 1 in the same run of 1s. (If there are multiple runs + // of 1s -- which isn't valid -- we'll behave as if only the lowest run was + // present, which seems reasonable.) + for (i = i + 1; i < 32; i++) { + if (!(mMask & (1 << i))) { + break; + } + } + mBitWidth = i - mRightShift; +} + +MOZ_ALWAYS_INLINE uint8_t +BitFields::Value::Get(uint32_t aValue) const +{ + // Extract the unscaled value. + uint32_t v = (aValue & mMask) >> mRightShift; + + // Idea: to upscale v precisely we need to duplicate its bits, possibly + // repeatedly, possibly partially in the last case, from bit 7 down to bit 0 + // in v2. For example: + // + // - mBitWidth=1: v2 = v<<7 | v<<6 | ... | v<<1 | v>>0 k -> kkkkkkkk + // - mBitWidth=2: v2 = v<<6 | v<<4 | v<<2 | v>>0 jk -> jkjkjkjk + // - mBitWidth=3: v2 = v<<5 | v<<2 | v>>1 ijk -> ijkijkij + // - mBitWidth=4: v2 = v<<4 | v>>0 hijk -> hijkhijk + // - mBitWidth=5: v2 = v<<3 | v>>2 ghijk -> ghijkghi + // - mBitWidth=6: v2 = v<<2 | v>>4 fghijk -> fghijkfg + // - mBitWidth=7: v2 = v<<1 | v>>6 efghijk -> efghijke + // - mBitWidth=8: v2 = v>>0 defghijk -> defghijk + // - mBitWidth=9: v2 = v>>1 cdefghijk -> cdefghij + // - mBitWidth=10: v2 = v>>2 bcdefghijk -> bcdefghi + // - mBitWidth=11: v2 = v>>3 abcdefghijk -> abcdefgh + // - etc. + // + uint8_t v2 = 0; + int32_t i; // must be a signed integer + for (i = 8 - mBitWidth; i > 0; i -= mBitWidth) { + v2 |= v << uint32_t(i); + } + v2 |= v >> uint32_t(-i); + return v2; +} + +MOZ_ALWAYS_INLINE uint8_t +BitFields::Value::GetAlpha(uint32_t aValue, bool& aHasAlphaOut) const +{ + if (mMask == 0x0) { + return 0xff; + } + aHasAlphaOut = true; + return Get(aValue); +} + +MOZ_ALWAYS_INLINE uint8_t +BitFields::Value::Get5(uint32_t aValue) const +{ + MOZ_ASSERT(mBitWidth == 5); + uint32_t v = (aValue & mMask) >> mRightShift; + return (v << 3u) | (v >> 2u); +} + +MOZ_ALWAYS_INLINE uint8_t +BitFields::Value::Get8(uint32_t aValue) const +{ + MOZ_ASSERT(mBitWidth == 8); + uint32_t v = (aValue & mMask) >> mRightShift; + return v; +} + +void +BitFields::SetR5G5B5() +{ + mRed.Set(0x7c00); + mGreen.Set(0x03e0); + mBlue.Set(0x001f); +} + +void +BitFields::SetR8G8B8() +{ + mRed.Set(0xff0000); + mGreen.Set(0xff00); + mBlue.Set(0x00ff); +} + +bool +BitFields::IsR5G5B5() const +{ + return mRed.mBitWidth == 5 && + mGreen.mBitWidth == 5 && + mBlue.mBitWidth == 5 && + mAlpha.mMask == 0x0; +} + +bool +BitFields::IsR8G8B8() const +{ + return mRed.mBitWidth == 8 && + mGreen.mBitWidth == 8 && + mBlue.mBitWidth == 8 && + mAlpha.mMask == 0x0; +} + +uint32_t* +nsBMPDecoder::RowBuffer() +{ + if (mDownscaler) { + return reinterpret_cast<uint32_t*>(mDownscaler->RowBuffer()) + mCurrentPos; + } + + // Convert from row (1..mHeight) to absolute line (0..mHeight-1). + int32_t line = (mH.mHeight < 0) + ? -mH.mHeight - mCurrentRow + : mCurrentRow - 1; + int32_t offset = line * mH.mWidth + mCurrentPos; + return reinterpret_cast<uint32_t*>(mImageData) + offset; +} + +void +nsBMPDecoder::FinishRow() +{ + if (mDownscaler) { + mDownscaler->CommitRow(); + + if (mDownscaler->HasInvalidation()) { + DownscalerInvalidRect invalidRect = mDownscaler->TakeInvalidRect(); + PostInvalidation(invalidRect.mOriginalSizeRect, + Some(invalidRect.mTargetSizeRect)); + } + } else { + PostInvalidation(IntRect(0, mCurrentRow, mH.mWidth, 1)); + } + mCurrentRow--; +} + +LexerResult +nsBMPDecoder::DoDecode(SourceBufferIterator& aIterator, IResumable* aOnResume) +{ + MOZ_ASSERT(!HasError(), "Shouldn't call DoDecode after error!"); + + return mLexer.Lex(aIterator, aOnResume, + [=](State aState, const char* aData, size_t aLength) { + switch (aState) { + case State::FILE_HEADER: return ReadFileHeader(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); + case State::COLOR_TABLE: return ReadColorTable(aData, aLength); + case State::GAP: return SkipGap(); + case State::AFTER_GAP: return AfterGap(); + case State::PIXEL_ROW: return ReadPixelRow(aData); + case State::RLE_SEGMENT: return ReadRLESegment(aData); + case State::RLE_DELTA: return ReadRLEDelta(aData); + case State::RLE_ABSOLUTE: return ReadRLEAbsolute(aData, aLength); + default: + MOZ_CRASH("Unknown State"); + } + }); +} + +LexerTransition<nsBMPDecoder::State> +nsBMPDecoder::ReadFileHeader(const char* aData, size_t aLength) +{ + mPreGapLength += aLength; + + bool signatureOk = aData[0] == 'B' && aData[1] == 'M'; + if (!signatureOk) { + return Transition::TerminateFailure(); + } + + // We ignore the filesize (aData + 2) and reserved (aData + 6) fields. + + mH.mDataOffset = LittleEndian::readUint32(aData + 10); + + return Transition::To(State::INFO_HEADER_SIZE, BIHSIZE_FIELD_LENGTH); +} + +// 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> +nsBMPDecoder::ReadInfoHeaderSize(const char* aData, size_t aLength) +{ + mPreGapLength += aLength; + + mH.mBIHSize = LittleEndian::readUint32(aData); + + bool bihSizeOk = mH.mBIHSize == InfoHeaderLength::WIN_V2 || + mH.mBIHSize == InfoHeaderLength::WIN_V3 || + mH.mBIHSize == InfoHeaderLength::WIN_V4 || + mH.mBIHSize == InfoHeaderLength::WIN_V5 || + (mH.mBIHSize >= InfoHeaderLength::OS2_V2_MIN && + mH.mBIHSize <= InfoHeaderLength::OS2_V2_MAX); + if (!bihSizeOk) { + return Transition::TerminateFailure(); + } + // ICO BMPs must have a WinBMPv3 header. nsICODecoder should have already + // terminated decoding if this isn't the case. + MOZ_ASSERT_IF(mIsWithinICO, mH.mBIHSize == InfoHeaderLength::WIN_V3); + + return Transition::To(State::INFO_HEADER_REST, + mH.mBIHSize - BIHSIZE_FIELD_LENGTH); +} + +LexerTransition<nsBMPDecoder::State> +nsBMPDecoder::ReadInfoHeaderRest(const char* aData, size_t aLength) +{ + mPreGapLength += aLength; + + // |mWidth| and |mHeight| may be signed (Windows) or unsigned (OS/2). We just + // read as unsigned because in practice that's good enough. + if (mH.mBIHSize == InfoHeaderLength::WIN_V2) { + mH.mWidth = LittleEndian::readUint16(aData + 0); + mH.mHeight = LittleEndian::readUint16(aData + 2); + // We ignore the planes (aData + 4) field; it should always be 1. + mH.mBpp = LittleEndian::readUint16(aData + 6); + } else { + mH.mWidth = LittleEndian::readUint32(aData + 0); + mH.mHeight = LittleEndian::readUint32(aData + 4); + // We ignore the planes (aData + 4) field; it should always be 1. + mH.mBpp = LittleEndian::readUint16(aData + 10); + + // For OS2-BMPv2 the info header may be as little as 16 bytes, so be + // careful for these fields. + mH.mCompression = aLength >= 16 ? LittleEndian::readUint32(aData + 12) : 0; + mH.mImageSize = aLength >= 20 ? LittleEndian::readUint32(aData + 16) : 0; + // We ignore the xppm (aData + 20) and yppm (aData + 24) fields. + mH.mNumColors = aLength >= 32 ? LittleEndian::readUint32(aData + 28) : 0; + // We ignore the important_colors (aData + 36) field. + + // For WinBMPv4, WinBMPv5 and (possibly) OS2-BMPv2 there are additional + // fields in the info header which we ignore, with the possible exception + // of the color bitfields (see below). + } + + // Run with MOZ_LOG=BMPDecoder:5 set to see this output. + MOZ_LOG(sBMPLog, LogLevel::Debug, + ("BMP: bihsize=%u, %d x %d, bpp=%u, compression=%u, colors=%u\n", + mH.mBIHSize, mH.mWidth, mH.mHeight, uint32_t(mH.mBpp), + mH.mCompression, mH.mNumColors)); + + // BMPs with negative width are invalid. Also, reject extremely wide images + // to keep the math sane. And reject INT_MIN as a height because you can't + // get its absolute value (because -INT_MIN is one more than INT_MAX). + const int32_t k64KWidth = 0x0000FFFF; + bool sizeOk = 0 <= mH.mWidth && mH.mWidth <= k64KWidth && + mH.mHeight != INT_MIN; + if (!sizeOk) { + return Transition::TerminateFailure(); + } + + // Check mBpp and mCompression. + bool bppCompressionOk = + (mH.mCompression == Compression::RGB && + (mH.mBpp == 1 || mH.mBpp == 4 || mH.mBpp == 8 || + mH.mBpp == 16 || mH.mBpp == 24 || mH.mBpp == 32)) || + (mH.mCompression == Compression::RLE8 && mH.mBpp == 8) || + (mH.mCompression == Compression::RLE4 && mH.mBpp == 4) || + (mH.mCompression == Compression::BITFIELDS && + // For BITFIELDS compression we require an exact match for one of the + // WinBMP BIH sizes; this clearly isn't an OS2 BMP. + (mH.mBIHSize == InfoHeaderLength::WIN_V3 || + mH.mBIHSize == InfoHeaderLength::WIN_V4 || + mH.mBIHSize == InfoHeaderLength::WIN_V5) && + (mH.mBpp == 16 || mH.mBpp == 32)); + if (!bppCompressionOk) { + return Transition::TerminateFailure(); + } + + // Initialize our current row to the top of the image. + mCurrentRow = AbsoluteHeight(); + + // Round it up to the nearest byte count, then pad to 4-byte boundary. + // Compute this even for a metadate decode because GetCompressedImageSize() + // relies on it. + mPixelRowSize = (mH.mBpp * mH.mWidth + 7) / 8; + uint32_t surplus = mPixelRowSize % 4; + if (surplus != 0) { + mPixelRowSize += 4 - surplus; + } + + size_t bitFieldsLengthStillToRead = 0; + if (mH.mCompression == Compression::BITFIELDS) { + // Need to read bitfields. + if (mH.mBIHSize >= InfoHeaderLength::WIN_V4) { + // Bitfields are present in the info header, so we can read them + // immediately. + mBitFields.ReadFromHeader(aData + 36, /* aReadAlpha = */ true); + } else { + // Bitfields are present after the info header, so we will read them in + // ReadBitfields(). + bitFieldsLengthStillToRead = BitFields::LENGTH; + } + } else if (mH.mBpp == 16) { + // No bitfields specified; use the default 5-5-5 values. + mBitFields.SetR5G5B5(); + } else if (mH.mBpp == 32) { + // No bitfields specified; use the default 8-8-8 values. + mBitFields.SetR8G8B8(); + } + + return Transition::To(State::BITFIELDS, bitFieldsLengthStillToRead); +} + +void +BitFields::ReadFromHeader(const char* aData, bool aReadAlpha) +{ + mRed.Set (LittleEndian::readUint32(aData + 0)); + mGreen.Set(LittleEndian::readUint32(aData + 4)); + mBlue.Set (LittleEndian::readUint32(aData + 8)); + if (aReadAlpha) { + mAlpha.Set(LittleEndian::readUint32(aData + 12)); + } +} + +LexerTransition<nsBMPDecoder::State> +nsBMPDecoder::ReadBitfields(const char* aData, size_t aLength) +{ + mPreGapLength += aLength; + + // If aLength is zero there are no bitfields to read, or we already read them + // in ReadInfoHeader(). + if (aLength != 0) { + mBitFields.ReadFromHeader(aData, /* aReadAlpha = */ false); + } + + // Note that RLE-encoded BMPs might be transparent because the 'delta' mode + // can skip pixels and cause implicit transparency. + mMayHaveTransparency = + mIsWithinICO || + mH.mCompression == Compression::RLE8 || + mH.mCompression == Compression::RLE4 || + (mH.mCompression == Compression::BITFIELDS && + mBitFields.mAlpha.IsPresent()); + if (mMayHaveTransparency) { + PostHasTransparency(); + } + + // Post our size to the superclass. + PostSize(mH.mWidth, AbsoluteHeight()); + + // We've now read all the headers. If we're doing a metadata decode, we're + // done. + if (IsMetadataDecode()) { + return Transition::TerminateSuccess(); + } + + // Set up the color table, if present; it'll be filled in by ReadColorTable(). + if (mH.mBpp <= 8) { + mNumColors = 1 << mH.mBpp; + if (0 < mH.mNumColors && mH.mNumColors < mNumColors) { + mNumColors = mH.mNumColors; + } + + // Always allocate and zero 256 entries, even though mNumColors might be + // smaller, because the file might erroneously index past mNumColors. + mColors = MakeUnique<ColorTableEntry[]>(256); + memset(mColors.get(), 0, 256 * sizeof(ColorTableEntry)); + + // OS/2 Bitmaps have no padding byte. + mBytesPerColor = (mH.mBIHSize == InfoHeaderLength::WIN_V2) ? 3 : 4; + } + + MOZ_ASSERT(!mImageData, "Already have a buffer allocated?"); + nsresult rv = AllocateFrame(/* aFrameNum = */ 0, OutputSize(), + FullOutputFrame(), + mMayHaveTransparency ? SurfaceFormat::B8G8R8A8 + : SurfaceFormat::B8G8R8X8); + if (NS_FAILED(rv)) { + return Transition::TerminateFailure(); + } + MOZ_ASSERT(mImageData, "Should have a buffer now"); + + if (mDownscaler) { + // BMPs store their rows in reverse order, so the downscaler needs to + // reverse them again when writing its output. Unless the height is + // negative! + rv = mDownscaler->BeginFrame(Size(), Nothing(), + mImageData, mMayHaveTransparency, + /* aFlipVertically = */ mH.mHeight >= 0); + if (NS_FAILED(rv)) { + return Transition::TerminateFailure(); + } + } + + return Transition::To(State::COLOR_TABLE, mNumColors * mBytesPerColor); +} + +LexerTransition<nsBMPDecoder::State> +nsBMPDecoder::ReadColorTable(const char* aData, size_t aLength) +{ + MOZ_ASSERT_IF(aLength != 0, mNumColors > 0 && mColors); + + mPreGapLength += aLength; + + for (uint32_t i = 0; i < mNumColors; i++) { + // The format is BGR or BGR0. + mColors[i].mBlue = uint8_t(aData[0]); + mColors[i].mGreen = uint8_t(aData[1]); + mColors[i].mRed = uint8_t(aData[2]); + aData += mBytesPerColor; + } + + // 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. + // + // If the gap is negative the file must be malformed (e.g. mH.mDataOffset + // points into the middle of the color palette instead of past the end) and + // we give up. + if (mPreGapLength > mH.mDataOffset) { + return Transition::TerminateFailure(); + } + + uint32_t gapLength = mH.mDataOffset - mPreGapLength; + return Transition::ToUnbuffered(State::AFTER_GAP, State::GAP, gapLength); +} + +LexerTransition<nsBMPDecoder::State> +nsBMPDecoder::SkipGap() +{ + return Transition::ContinueUnbuffered(State::GAP); +} + +LexerTransition<nsBMPDecoder::State> +nsBMPDecoder::AfterGap() +{ + // If there are no pixels we can stop. + // + // XXX: normally, if there are no pixels we will have stopped decoding before + // now, outside of this decoder. However, if the BMP is within an ICO file, + // it's possible that the ICO claimed the image had a non-zero size while the + // BMP claims otherwise. This test is to catch that awkward case. If we ever + // come up with a more general solution to this ICO-and-BMP-disagree-on-size + // problem, this test can be removed. + if (mH.mWidth == 0 || mH.mHeight == 0) { + return Transition::TerminateSuccess(); + } + + bool hasRLE = mH.mCompression == Compression::RLE8 || + mH.mCompression == Compression::RLE4; + return hasRLE + ? Transition::To(State::RLE_SEGMENT, RLE::SEGMENT_LENGTH) + : Transition::To(State::PIXEL_ROW, mPixelRowSize); +} + +LexerTransition<nsBMPDecoder::State> +nsBMPDecoder::ReadPixelRow(const char* aData) +{ + MOZ_ASSERT(mCurrentRow > 0); + MOZ_ASSERT(mCurrentPos == 0); + + const uint8_t* src = reinterpret_cast<const uint8_t*>(aData); + uint32_t* dst = RowBuffer(); + uint32_t lpos = mH.mWidth; + switch (mH.mBpp) { + case 1: + while (lpos > 0) { + int8_t bit; + uint8_t idx; + for (bit = 7; bit >= 0 && lpos > 0; bit--) { + idx = (*src >> bit) & 1; + SetPixel(dst, idx, mColors); + --lpos; + } + ++src; + } + break; + + case 4: + while (lpos > 0) { + Set4BitPixel(dst, *src, lpos, mColors); + ++src; + } + break; + + case 8: + while (lpos > 0) { + SetPixel(dst, *src, mColors); + --lpos; + ++src; + } + break; + + case 16: + if (mBitFields.IsR5G5B5()) { + // Specialize this common case. + while (lpos > 0) { + uint16_t val = LittleEndian::readUint16(src); + SetPixel(dst, mBitFields.mRed.Get5(val), + mBitFields.mGreen.Get5(val), + mBitFields.mBlue.Get5(val)); + --lpos; + src += 2; + } + } else { + bool anyHasAlpha = false; + while (lpos > 0) { + uint16_t val = LittleEndian::readUint16(src); + SetPixel(dst, mBitFields.mRed.Get(val), + mBitFields.mGreen.Get(val), + mBitFields.mBlue.Get(val), + mBitFields.mAlpha.GetAlpha(val, anyHasAlpha)); + --lpos; + src += 2; + } + if (anyHasAlpha) { + MOZ_ASSERT(mMayHaveTransparency); + mDoesHaveTransparency = true; + } + } + break; + + case 24: + while (lpos > 0) { + SetPixel(dst, src[2], src[1], src[0]); + --lpos; + src += 3; + } + break; + + case 32: + if (mH.mCompression == Compression::RGB && mIsWithinICO && + mH.mBpp == 32) { + // This is a special case only used for 32bpp WinBMPv3-ICO files, which + // could be in either 0RGB or ARGB format. We start by assuming it's + // an 0RGB image. If we hit a non-zero alpha value, then we know it's + // actually an ARGB image, and change tack accordingly. + // (Note: a fully-transparent ARGB image is indistinguishable from a + // 0RGB image, and we will render such an image as a 0RGB image, i.e. + // opaquely. This is unlikely to be a problem in practice.) + while (lpos > 0) { + if (!mDoesHaveTransparency && src[3] != 0) { + // Up until now this looked like an 0RGB image, but we now know + // it's actually an ARGB image. Which means every pixel we've seen + // so far has been fully transparent. So we go back and redo them. + + // Tell the Downscaler to go back to the start. + if (mDownscaler) { + mDownscaler->ResetForNextProgressivePass(); + } + + // Redo the complete rows we've already done. + MOZ_ASSERT(mCurrentPos == 0); + int32_t currentRow = mCurrentRow; + mCurrentRow = AbsoluteHeight(); + while (mCurrentRow > currentRow) { + dst = RowBuffer(); + for (int32_t i = 0; i < mH.mWidth; i++) { + SetPixel(dst, 0, 0, 0, 0); + } + FinishRow(); + } + + // Redo the part of this row we've already done. + dst = RowBuffer(); + int32_t n = mH.mWidth - lpos; + for (int32_t i = 0; i < n; i++) { + SetPixel(dst, 0, 0, 0, 0); + } + + MOZ_ASSERT(mMayHaveTransparency); + mDoesHaveTransparency = true; + } + + // If mDoesHaveTransparency is false, treat this as an 0RGB image. + // Otherwise, treat this as an ARGB image. + SetPixel(dst, src[2], src[1], src[0], + mDoesHaveTransparency ? src[3] : 0xff); + src += 4; + --lpos; + } + } else if (mBitFields.IsR8G8B8()) { + // Specialize this common case. + while (lpos > 0) { + uint32_t val = LittleEndian::readUint32(src); + SetPixel(dst, mBitFields.mRed.Get8(val), + mBitFields.mGreen.Get8(val), + mBitFields.mBlue.Get8(val)); + --lpos; + src += 4; + } + } else { + bool anyHasAlpha = false; + while (lpos > 0) { + uint32_t val = LittleEndian::readUint32(src); + SetPixel(dst, mBitFields.mRed.Get(val), + mBitFields.mGreen.Get(val), + mBitFields.mBlue.Get(val), + mBitFields.mAlpha.GetAlpha(val, anyHasAlpha)); + --lpos; + src += 4; + } + if (anyHasAlpha) { + MOZ_ASSERT(mMayHaveTransparency); + mDoesHaveTransparency = true; + } + } + break; + + default: + MOZ_CRASH("Unsupported color depth; earlier check didn't catch it?"); + } + + FinishRow(); + return mCurrentRow == 0 + ? Transition::TerminateSuccess() + : Transition::To(State::PIXEL_ROW, mPixelRowSize); +} + +LexerTransition<nsBMPDecoder::State> +nsBMPDecoder::ReadRLESegment(const char* aData) +{ + if (mCurrentRow == 0) { + return Transition::TerminateSuccess(); + } + + uint8_t byte1 = uint8_t(aData[0]); + uint8_t byte2 = uint8_t(aData[1]); + + if (byte1 != RLE::ESCAPE) { + // Encoded mode consists of two bytes: byte1 specifies the number of + // consecutive pixels to be drawn using the color index contained in + // byte2. + // + // Work around bitmaps that specify too many pixels. + uint32_t pixelsNeeded = + std::min<uint32_t>(mH.mWidth - mCurrentPos, byte1); + if (pixelsNeeded) { + uint32_t* dst = RowBuffer(); + mCurrentPos += pixelsNeeded; + if (mH.mCompression == Compression::RLE8) { + do { + SetPixel(dst, byte2, mColors); + pixelsNeeded --; + } while (pixelsNeeded); + } else { + do { + Set4BitPixel(dst, byte2, pixelsNeeded, mColors); + } while (pixelsNeeded); + } + } + return Transition::To(State::RLE_SEGMENT, RLE::SEGMENT_LENGTH); + } + + if (byte2 == RLE::ESCAPE_EOL) { + mCurrentPos = 0; + FinishRow(); + return mCurrentRow == 0 + ? Transition::TerminateSuccess() + : Transition::To(State::RLE_SEGMENT, RLE::SEGMENT_LENGTH); + } + + if (byte2 == RLE::ESCAPE_EOF) { + return Transition::TerminateSuccess(); + } + + if (byte2 == RLE::ESCAPE_DELTA) { + return Transition::To(State::RLE_DELTA, RLE::DELTA_LENGTH); + } + + // Absolute mode. |byte2| gives the number of pixels. The length depends on + // whether it's 4-bit or 8-bit RLE. Also, the length must be even (and zero + // padding is used to achieve this when necessary). + MOZ_ASSERT(mAbsoluteModeNumPixels == 0); + mAbsoluteModeNumPixels = byte2; + uint32_t length = byte2; + if (mH.mCompression == Compression::RLE4) { + length = (length + 1) / 2; // halve, rounding up + } + if (length & 1) { + length++; + } + return Transition::To(State::RLE_ABSOLUTE, length); +} + +LexerTransition<nsBMPDecoder::State> +nsBMPDecoder::ReadRLEDelta(const char* aData) +{ + // Delta encoding makes it possible to skip pixels making part of the image + // transparent. + MOZ_ASSERT(mMayHaveTransparency); + mDoesHaveTransparency = true; + + if (mDownscaler) { + // Clear the skipped pixels. (This clears to the end of the row, + // which is perfect if there's a Y delta and harmless if not). + mDownscaler->ClearRestOfRow(/* aStartingAtCol = */ mCurrentPos); + } + + // Handle the XDelta. + mCurrentPos += uint8_t(aData[0]); + if (mCurrentPos > mH.mWidth) { + mCurrentPos = mH.mWidth; + } + + // Handle the Y Delta. + int32_t yDelta = std::min<int32_t>(uint8_t(aData[1]), mCurrentRow); + mCurrentRow -= yDelta; + + if (mDownscaler && yDelta > 0) { + // Commit the current row (the first of the skipped rows). + mDownscaler->CommitRow(); + + // Clear and commit the remaining skipped rows. + for (int32_t line = 1; line < yDelta; line++) { + mDownscaler->ClearRow(); + mDownscaler->CommitRow(); + } + } + + return mCurrentRow == 0 + ? Transition::TerminateSuccess() + : Transition::To(State::RLE_SEGMENT, RLE::SEGMENT_LENGTH); +} + +LexerTransition<nsBMPDecoder::State> +nsBMPDecoder::ReadRLEAbsolute(const char* aData, size_t aLength) +{ + uint32_t n = mAbsoluteModeNumPixels; + mAbsoluteModeNumPixels = 0; + + if (mCurrentPos + n > uint32_t(mH.mWidth)) { + // Bad data. Stop decoding; at least part of the image may have been + // decoded. + return Transition::TerminateSuccess(); + } + + // In absolute mode, n represents the number of pixels that follow, each of + // which contains the color index of a single pixel. + uint32_t* dst = RowBuffer(); + uint32_t iSrc = 0; + uint32_t* oldPos = dst; + if (mH.mCompression == Compression::RLE8) { + while (n > 0) { + SetPixel(dst, aData[iSrc], mColors); + n--; + iSrc++; + } + } else { + while (n > 0) { + Set4BitPixel(dst, aData[iSrc], n, mColors); + iSrc++; + } + } + mCurrentPos += dst - oldPos; + + // We should read all the data (unless the last byte is zero padding). + MOZ_ASSERT(iSrc == aLength - 1 || iSrc == aLength); + + return Transition::To(State::RLE_SEGMENT, RLE::SEGMENT_LENGTH); +} + +} // namespace image +} // namespace mozilla |