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+/* -*- 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.
+//
+// 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.
+// - 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 "mozilla/UniquePtrExtensions.h"
+
+#include "RasterImage.h"
+#include "SurfacePipeFactory.h"
+#include "gfxPlatform.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;
+
+static double FixedPoint2Dot30_To_Double(uint32_t aFixed) {
+ constexpr double factor = 1.0 / 1073741824.0; // 2^-30
+ return double(aFixed) * factor;
+}
+
+static float FixedPoint16Dot16_To_Float(uint32_t aFixed) {
+ constexpr double factor = 1.0 / 65536.0; // 2^-16
+ return double(aFixed) * factor;
+}
+
+static float CalRbgEndpointToQcms(const CalRgbEndpoint& aIn,
+ qcms_CIE_xyY& aOut) {
+ aOut.x = FixedPoint2Dot30_To_Double(aIn.mX);
+ aOut.y = FixedPoint2Dot30_To_Double(aIn.mY);
+ aOut.Y = FixedPoint2Dot30_To_Double(aIn.mZ);
+ return FixedPoint16Dot16_To_Float(aIn.mGamma);
+}
+
+static void ReadCalRgbEndpoint(const char* aData, uint32_t aEndpointOffset,
+ uint32_t aGammaOffset, CalRgbEndpoint& aOut) {
+ aOut.mX = LittleEndian::readUint32(aData + aEndpointOffset);
+ aOut.mY = LittleEndian::readUint32(aData + aEndpointOffset + 4);
+ aOut.mZ = LittleEndian::readUint32(aData + aEndpointOffset + 8);
+ aOut.mGamma = LittleEndian::readUint32(aData + aGammaOffset);
+}
+
+/// 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++ = gfxPackedPixelNoPreMultiply(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,
+ bool aForClipboard)
+ : Decoder(aImage),
+ mLexer(Transition::To(aState, aLength), Transition::TerminateSuccess()),
+ mIsWithinICO(false),
+ mIsForClipboard(aForClipboard),
+ 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 or from the clipboard.
+nsBMPDecoder::nsBMPDecoder(RasterImage* aImage, bool aForClipboard)
+ : nsBMPDecoder(aImage,
+ 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,
+ /* aForClipboard */ false) {
+ 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();
+ }
+
+ 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() { return mRowBuffer.get() + mCurrentPos; }
+
+void nsBMPDecoder::ClearRowBufferRemainder() {
+ int32_t len = mH.mWidth - mCurrentPos;
+ memset(RowBuffer(), mMayHaveTransparency ? 0 : 0xFF, len * sizeof(uint32_t));
+}
+
+void nsBMPDecoder::FinishRow() {
+ mPipe.WriteBuffer(mRowBuffer.get());
+ Maybe<SurfaceInvalidRect> invalidRect = mPipe.TakeInvalidRect();
+ if (invalidRect) {
+ PostInvalidation(invalidRect->mInputSpaceRect,
+ Some(invalidRect->mOutputSpaceRect));
+ }
+ 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::SKIP_TO_COLOR_PROFILE:
+ return Transition::ContinueUnbuffered(State::SKIP_TO_COLOR_PROFILE);
+ case State::FOUND_COLOR_PROFILE:
+ return Transition::To(State::COLOR_PROFILE,
+ mH.mColorSpace.mProfile.mLength);
+ case State::COLOR_PROFILE:
+ return ReadColorProfile(aData, aLength);
+ case State::ALLOCATE_SURFACE:
+ return AllocateSurface();
+ 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) {
+ mH.mBIHSize = LittleEndian::readUint32(aData);
+
+ // Data offset can be wrong so fix it using the BIH size.
+ if (!mIsForClipboard && mH.mDataOffset < mPreGapLength + mH.mBIHSize) {
+ mH.mDataOffset = mPreGapLength + mH.mBIHSize;
+ }
+
+ mPreGapLength += aLength;
+
+ 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.
+
+ // Read color management properties we may need later.
+ mH.mCsType =
+ aLength >= 56
+ ? static_cast<InfoColorSpace>(LittleEndian::readUint32(aData + 52))
+ : InfoColorSpace::SRGB;
+ mH.mCsIntent = aLength >= 108 ? static_cast<InfoColorIntent>(
+ LittleEndian::readUint32(aData + 104))
+ : InfoColorIntent::IMAGES;
+
+ switch (mH.mCsType) {
+ case InfoColorSpace::CALIBRATED_RGB:
+ if (aLength >= 104) {
+ ReadCalRgbEndpoint(aData, 56, 92, mH.mColorSpace.mCalibrated.mRed);
+ ReadCalRgbEndpoint(aData, 68, 96, mH.mColorSpace.mCalibrated.mGreen);
+ ReadCalRgbEndpoint(aData, 80, 100, mH.mColorSpace.mCalibrated.mBlue);
+ } else {
+ mH.mCsType = InfoColorSpace::SRGB;
+ }
+ break;
+ case InfoColorSpace::EMBEDDED:
+ if (aLength >= 116) {
+ mH.mColorSpace.mProfile.mOffset =
+ LittleEndian::readUint32(aData + 108);
+ mH.mColorSpace.mProfile.mLength =
+ LittleEndian::readUint32(aData + 112);
+ } else {
+ mH.mCsType = InfoColorSpace::SRGB;
+ }
+ break;
+ case InfoColorSpace::LINKED:
+ case InfoColorSpace::SRGB:
+ case InfoColorSpace::WIN:
+ default:
+ // Nothing to be done at this time.
+ break;
+ }
+
+ // 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).
+ }
+
+ // The height for BMPs embedded inside an ICO includes spaces for the AND
+ // mask even if it is not present, thus we need to adjust for that here.
+ if (mIsWithinICO) {
+ // XXX(seth): Should we really be writing the absolute value from
+ // the BIH below? Seems like this could be problematic for inverted BMPs.
+ mH.mHeight = abs(mH.mHeight) / 2;
+ }
+
+ // 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, "
+ "data-offset=%u\n",
+ mH.mBIHSize, mH.mWidth, mH.mHeight, uint32_t(mH.mBpp),
+ mH.mCompression, mH.mNumColors, mH.mDataOffset));
+
+ // 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);
+
+ // 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().
+ 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());
+ if (HasError()) {
+ return Transition::TerminateFailure();
+ }
+
+ // 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 = MakeUniqueFallible<ColorTableEntry[]>(256);
+ if (NS_WARN_IF(!mColors)) {
+ return Transition::TerminateFailure();
+ }
+ memset(mColors.get(), 0, 256 * sizeof(ColorTableEntry));
+
+ // OS/2 Bitmaps have no padding byte.
+ mBytesPerColor = (mH.mBIHSize == InfoHeaderLength::WIN_V2) ? 3 : 4;
+ }
+
+ if (mCMSMode != CMSMode::Off) {
+ switch (mH.mCsType) {
+ case InfoColorSpace::EMBEDDED:
+ return SeekColorProfile(aLength);
+ case InfoColorSpace::CALIBRATED_RGB:
+ PrepareCalibratedColorProfile();
+ break;
+ case InfoColorSpace::SRGB:
+ case InfoColorSpace::WIN:
+ MOZ_LOG(sBMPLog, LogLevel::Debug, ("using sRGB color profile\n"));
+ if (mColors) {
+ // We will transform the color table instead of the output pixels.
+ mTransform = GetCMSsRGBTransform(SurfaceFormat::R8G8B8);
+ } else {
+ mTransform = GetCMSsRGBTransform(SurfaceFormat::OS_RGBA);
+ }
+ break;
+ case InfoColorSpace::LINKED:
+ default:
+ // Not supported, no color management.
+ MOZ_LOG(sBMPLog, LogLevel::Debug, ("color space type not provided\n"));
+ break;
+ }
+ }
+
+ return Transition::To(State::ALLOCATE_SURFACE, 0);
+}
+
+void nsBMPDecoder::PrepareCalibratedColorProfile() {
+ // BMP does not define a white point. Use the same as sRGB. This matches what
+ // Chrome does as well.
+ qcms_CIE_xyY white_point = qcms_white_point_sRGB();
+
+ qcms_CIE_xyYTRIPLE primaries;
+ float redGamma =
+ CalRbgEndpointToQcms(mH.mColorSpace.mCalibrated.mRed, primaries.red);
+ float greenGamma =
+ CalRbgEndpointToQcms(mH.mColorSpace.mCalibrated.mGreen, primaries.green);
+ float blueGamma =
+ CalRbgEndpointToQcms(mH.mColorSpace.mCalibrated.mBlue, primaries.blue);
+
+ // Explicitly verify the profile because sometimes the values from the BMP
+ // header are just garbage.
+ mInProfile = qcms_profile_create_rgb_with_gamma_set(
+ white_point, primaries, redGamma, greenGamma, blueGamma);
+ if (mInProfile && qcms_profile_is_bogus(mInProfile)) {
+ // Bad profile, just use sRGB instead. Release the profile here, so that
+ // our destructor doesn't assume we are the owner for the transform.
+ qcms_profile_release(mInProfile);
+ mInProfile = nullptr;
+ }
+
+ if (mInProfile) {
+ MOZ_LOG(sBMPLog, LogLevel::Debug, ("using calibrated RGB color profile\n"));
+ PrepareColorProfileTransform();
+ } else {
+ MOZ_LOG(sBMPLog, LogLevel::Debug,
+ ("failed to create calibrated RGB color profile, using sRGB\n"));
+ if (mColors) {
+ // We will transform the color table instead of the output pixels.
+ mTransform = GetCMSsRGBTransform(SurfaceFormat::R8G8B8);
+ } else {
+ mTransform = GetCMSsRGBTransform(SurfaceFormat::OS_RGBA);
+ }
+ }
+}
+
+void nsBMPDecoder::PrepareColorProfileTransform() {
+ if (!mInProfile || !GetCMSOutputProfile()) {
+ return;
+ }
+
+ qcms_data_type inType;
+ qcms_data_type outType;
+ if (mColors) {
+ // We will transform the color table instead of the output pixels.
+ inType = QCMS_DATA_RGB_8;
+ outType = QCMS_DATA_RGB_8;
+ } else {
+ inType = gfxPlatform::GetCMSOSRGBAType();
+ outType = inType;
+ }
+
+ qcms_intent intent;
+ switch (mH.mCsIntent) {
+ case InfoColorIntent::BUSINESS:
+ intent = QCMS_INTENT_SATURATION;
+ break;
+ case InfoColorIntent::GRAPHICS:
+ intent = QCMS_INTENT_RELATIVE_COLORIMETRIC;
+ break;
+ case InfoColorIntent::ABS_COLORIMETRIC:
+ intent = QCMS_INTENT_ABSOLUTE_COLORIMETRIC;
+ break;
+ case InfoColorIntent::IMAGES:
+ default:
+ intent = QCMS_INTENT_PERCEPTUAL;
+ break;
+ }
+
+ mTransform = qcms_transform_create(mInProfile, inType, GetCMSOutputProfile(),
+ outType, intent);
+ if (!mTransform) {
+ MOZ_LOG(sBMPLog, LogLevel::Debug,
+ ("failed to create color profile transform\n"));
+ }
+}
+
+LexerTransition<nsBMPDecoder::State> nsBMPDecoder::SeekColorProfile(
+ size_t aLength) {
+ // The offset needs to be at least after the color table.
+ uint32_t offset = mH.mColorSpace.mProfile.mOffset;
+ if (offset <= mH.mBIHSize + aLength + mNumColors * mBytesPerColor ||
+ mH.mColorSpace.mProfile.mLength == 0) {
+ return Transition::To(State::ALLOCATE_SURFACE, 0);
+ }
+
+ // We have already read the header and bitfields.
+ offset -= mH.mBIHSize + aLength;
+
+ // We need to skip ahead to search for the embedded color profile. We want
+ // to return to this point once we read it.
+ mReturnIterator = mLexer.Clone(*mIterator, SIZE_MAX);
+ if (!mReturnIterator) {
+ return Transition::TerminateFailure();
+ }
+
+ return Transition::ToUnbuffered(State::FOUND_COLOR_PROFILE,
+ State::SKIP_TO_COLOR_PROFILE, offset);
+}
+
+LexerTransition<nsBMPDecoder::State> nsBMPDecoder::ReadColorProfile(
+ const char* aData, size_t aLength) {
+ mInProfile = qcms_profile_from_memory(aData, aLength);
+ if (mInProfile) {
+ MOZ_LOG(sBMPLog, LogLevel::Debug, ("using embedded color profile\n"));
+ PrepareColorProfileTransform();
+ }
+
+ // Jump back to where we left off.
+ mIterator = std::move(mReturnIterator);
+ return Transition::To(State::ALLOCATE_SURFACE, 0);
+}
+
+LexerTransition<nsBMPDecoder::State> nsBMPDecoder::AllocateSurface() {
+ SurfaceFormat format;
+ SurfacePipeFlags pipeFlags = SurfacePipeFlags();
+
+ if (mMayHaveTransparency) {
+ format = SurfaceFormat::OS_RGBA;
+ if (!(GetSurfaceFlags() & SurfaceFlags::NO_PREMULTIPLY_ALPHA)) {
+ pipeFlags |= SurfacePipeFlags::PREMULTIPLY_ALPHA;
+ }
+ } else {
+ format = SurfaceFormat::OS_RGBX;
+ }
+
+ if (mH.mHeight >= 0) {
+ // BMPs store their rows in reverse order, so we may need to flip.
+ pipeFlags |= SurfacePipeFlags::FLIP_VERTICALLY;
+ }
+
+ mRowBuffer.reset(new (fallible) uint32_t[mH.mWidth]);
+ if (!mRowBuffer) {
+ return Transition::TerminateFailure();
+ }
+
+ // Only give the color transform to the SurfacePipe if we are not transforming
+ // the color table in advance.
+ qcms_transform* transform = mColors ? nullptr : mTransform;
+
+ Maybe<SurfacePipe> pipe = SurfacePipeFactory::CreateSurfacePipe(
+ this, Size(), OutputSize(), FullFrame(), format, format, Nothing(),
+ transform, pipeFlags);
+ if (!pipe) {
+ return Transition::TerminateFailure();
+ }
+
+ mPipe = std::move(*pipe);
+ ClearRowBufferRemainder();
+ 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;
+ }
+
+ // If we have a color table and a transform, we can avoid transforming each
+ // pixel by doing the table in advance. We color manage every entry in the
+ // table, even if it is smaller in case the BMP is malformed and overruns
+ // its stated color range.
+ if (mColors && mTransform) {
+ qcms_transform_data(mTransform, mColors.get(), mColors.get(), 256);
+ }
+
+ // If we are decoding a BMP from the clipboard, we did not know the data
+ // offset in advance. It is just defined as 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.
+ //
+ // 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 SurfacePipe to go back to the start.
+ mPipe.ResetToFirstRow();
+
+ // Redo the complete rows we've already done.
+ MOZ_ASSERT(mCurrentPos == 0);
+ int32_t currentRow = mCurrentRow;
+ mCurrentRow = AbsoluteHeight();
+ ClearRowBufferRemainder();
+ while (mCurrentRow > currentRow) {
+ FinishRow();
+ }
+
+ // Reset the row pointer back to where we started.
+ dst = RowBuffer() + (mH.mWidth - lpos);
+
+ 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) {
+ ClearRowBufferRemainder();
+ 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;
+
+ // 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).
+ ClearRowBufferRemainder();
+
+ // 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);
+ if (yDelta > 0) {
+ // Commit the current row (the first of the skipped rows).
+ FinishRow();
+
+ // Clear and commit the remaining skipped rows. We want to be careful not
+ // to change mCurrentPos here.
+ memset(mRowBuffer.get(), 0, mH.mWidth * sizeof(uint32_t));
+ for (int32_t line = 1; line < yDelta; line++) {
+ FinishRow();
+ }
+ }
+
+ 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)) {
+ // Some DIB RLE8 encoders count a padding byte as the absolute mode
+ // pixel number at the end of the row.
+ if (mH.mCompression == Compression::RLE8 && n > 0 && (n & 1) == 0 &&
+ mCurrentPos + n - uint32_t(mH.mWidth) == 1 && aLength > 0 &&
+ aData[aLength - 1] == 0) {
+ n--;
+ } else {
+ // 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