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gecko/image/decoders/nsBMPDecoder.cpp

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/* vim:set tw=80 expandtab softtabstop=4 ts=4 sw=4: */
/* 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/. */
// I got the format description from http://www.daubnet.com/formats/BMP.html
// This is a Cross-Platform BMP Decoder, which should work everywhere, including
// Big-Endian machines like the PowerPC.
#include <stdlib.h>
#include "ImageLogging.h"
#include "mozilla/Endian.h"
#include "mozilla/Likely.h"
#include "nsBMPDecoder.h"
#include "nsIInputStream.h"
#include "RasterImage.h"
#include <algorithm>
namespace mozilla {
namespace image {
#ifdef PR_LOGGING
static PRLogModuleInfo*
GetBMPLog()
{
static PRLogModuleInfo* sBMPLog;
if (!sBMPLog) {
sBMPLog = PR_NewLogModule("BMPDecoder");
}
return sBMPLog;
}
#endif
// Convert from row (1..height) to absolute line (0..height-1)
#define LINE(row) ((mBIH.height < 0) ? (-mBIH.height - (row)) : ((row) - 1))
#define PIXEL_OFFSET(row, col) (LINE(row) * mBIH.width + col)
nsBMPDecoder::nsBMPDecoder(RasterImage& aImage)
: Decoder(aImage)
{
mColors = nullptr;
mRow = nullptr;
mCurPos = mPos = mNumColors = mRowBytes = 0;
mOldLine = mCurLine = 1; // Otherwise decoder will never start
mState = eRLEStateInitial;
mStateData = 0;
mLOH = WIN_V3_HEADER_LENGTH;
mUseAlphaData = mHaveAlphaData = false;
}
nsBMPDecoder::~nsBMPDecoder()
{
delete[] mColors;
if (mRow) {
moz_free(mRow);
}
}
// Sets whether or not the BMP will use alpha data
void
nsBMPDecoder::SetUseAlphaData(bool useAlphaData)
{
mUseAlphaData = useAlphaData;
}
// Obtains the bits per pixel from the internal BIH header
int32_t
nsBMPDecoder::GetBitsPerPixel() const
{
return mBIH.bpp;
}
// Obtains the width from the internal BIH header
int32_t
nsBMPDecoder::GetWidth() const
{
return mBIH.width;
}
// Obtains the abs-value of the height from the internal BIH header
int32_t
nsBMPDecoder::GetHeight() const
{
return abs(mBIH.height);
}
// Obtains the internal output image buffer
uint32_t*
nsBMPDecoder::GetImageData()
{
return reinterpret_cast<uint32_t*>(mImageData);
}
// Obtains the size of the compressed image resource
int32_t
nsBMPDecoder::GetCompressedImageSize() const
{
// For everything except BI_RGB the header field must be defined
if (mBIH.compression != BI_RGB) {
return mBIH.image_size;
}
// mBIH.image_size isn't always filled for BI_RGB so calculate it manually
// The pixel array size is calculated based on extra 4 byte boundary padding
uint32_t rowSize = (mBIH.bpp * mBIH.width + 7) / 8; // + 7 to round up
// Pad to DWORD Boundary
if (rowSize % 4) {
rowSize += (4 - (rowSize % 4));
}
// The height should be the absolute value of what the height is in the BIH.
// If positive the bitmap is stored bottom to top, otherwise top to bottom
int32_t pixelArraySize = rowSize * GetHeight();
return pixelArraySize;
}
// Obtains whether or not a BMP file had alpha data in its 4th byte
// for 32BPP bitmaps. Only use after the bitmap has been processed.
bool
nsBMPDecoder::HasAlphaData() const
{
return mHaveAlphaData;
}
void
nsBMPDecoder::FinishInternal()
{
// We shouldn't be called in error cases
NS_ABORT_IF_FALSE(!HasError(), "Can't call FinishInternal on error!");
// We should never make multiple frames
NS_ABORT_IF_FALSE(GetFrameCount() <= 1, "Multiple BMP frames?");
// Send notifications if appropriate
if (!IsSizeDecode() && HasSize()) {
// Invalidate
nsIntRect r(0, 0, mBIH.width, GetHeight());
PostInvalidation(r);
if (mUseAlphaData) {
PostFrameStop(FrameBlender::kFrameHasAlpha);
} else {
PostFrameStop(FrameBlender::kFrameOpaque);
}
PostDecodeDone();
}
}
// ----------------------------------------
// Actual Data Processing
// ----------------------------------------
static void
calcBitmask(uint32_t aMask, uint8_t& aBegin, uint8_t& aLength)
{
// find the rightmost 1
uint8_t pos;
bool started = false;
aBegin = aLength = 0;
for (pos = 0; pos <= 31; pos++) {
if (!started && (aMask & (1 << pos))) {
aBegin = pos;
started = true;
} else if (started && !(aMask & (1 << pos))) {
aLength = pos - aBegin;
break;
}
}
}
NS_METHOD
nsBMPDecoder::CalcBitShift()
{
uint8_t begin, length;
// red
calcBitmask(mBitFields.red, begin, length);
mBitFields.redRightShift = begin;
mBitFields.redLeftShift = 8 - length;
// green
calcBitmask(mBitFields.green, begin, length);
mBitFields.greenRightShift = begin;
mBitFields.greenLeftShift = 8 - length;
// blue
calcBitmask(mBitFields.blue, begin, length);
mBitFields.blueRightShift = begin;
mBitFields.blueLeftShift = 8 - length;
return NS_OK;
}
void
nsBMPDecoder::WriteInternal(const char* aBuffer, uint32_t aCount,
DecodeStrategy)
{
NS_ABORT_IF_FALSE(!HasError(), "Shouldn't call WriteInternal after error!");
// aCount=0 means EOF, mCurLine=0 means we're past end of image
if (!aCount || !mCurLine) {
return;
}
// This code assumes that mRawBuf == WIN_V3_INTERNAL_BIH_LENGTH
// and that sizeof(mRawBuf) >= BFH_INTERNAL_LENGTH
MOZ_ASSERT(sizeof(mRawBuf) == WIN_V3_INTERNAL_BIH_LENGTH);
MOZ_ASSERT(sizeof(mRawBuf) >= BFH_INTERNAL_LENGTH);
MOZ_ASSERT(OS2_INTERNAL_BIH_LENGTH < WIN_V3_INTERNAL_BIH_LENGTH);
// This code also assumes it's working with a byte array
MOZ_ASSERT(sizeof(mRawBuf[0]) == 1);
if (mPos < BFH_INTERNAL_LENGTH) { /* In BITMAPFILEHEADER */
// BFH_INTERNAL_LENGTH < sizeof(mRawBuf)
// mPos < BFH_INTERNAL_LENGTH
// BFH_INTERNAL_LENGTH - mPos < sizeof(mRawBuf)
// so toCopy <= BFH_INTERNAL_LENGTH
// so toCopy < sizeof(mRawBuf)
// so toCopy > 0 && toCopy <= BFH_INTERNAL_LENGTH
uint32_t toCopy = BFH_INTERNAL_LENGTH - mPos;
if (toCopy > aCount) {
toCopy = aCount;
}
// mRawBuf is a byte array of size WIN_V3_INTERNAL_BIH_LENGTH
// (verified above)
// mPos is < BFH_INTERNAL_LENGTH
// BFH_INTERNAL_LENGTH < WIN_V3_INTERNAL_BIH_LENGTH
// so mPos < sizeof(mRawBuf)
//
// Therefore this assert should hold
MOZ_ASSERT(mPos < sizeof(mRawBuf));
// toCopy <= BFH_INTERNAL_LENGTH
// mPos >= 0 && mPos < BFH_INTERNAL_LENGTH
// sizeof(mRawBuf) >= BFH_INTERNAL_LENGTH (verified above)
//
// Therefore this assert should hold
MOZ_ASSERT(mPos + toCopy <= sizeof(mRawBuf));
memcpy(mRawBuf + mPos, aBuffer, toCopy);
mPos += toCopy;
aCount -= toCopy;
aBuffer += toCopy;
}
if (mPos == BFH_INTERNAL_LENGTH) {
ProcessFileHeader();
if (mBFH.signature[0] != 'B' || mBFH.signature[1] != 'M') {
PostDataError();
return;
}
if (mBFH.bihsize == OS2_BIH_LENGTH) {
mLOH = OS2_HEADER_LENGTH;
}
}
if (mPos >= BFH_INTERNAL_LENGTH && mPos < mLOH) { /* In BITMAPINFOHEADER */
// mLOH == WIN_V3_HEADER_LENGTH || mLOH == OS2_HEADER_LENGTH
// OS2_HEADER_LENGTH < WIN_V3_HEADER_LENGTH
// BFH_INTERNAL_LENGTH < OS2_HEADER_LENGTH
// BFH_INTERNAL_LENGTH < WIN_V3_HEADER_LENGTH
//
// So toCopy is in the range
// 1 to (WIN_V3_HEADER_LENGTH - BFH_INTERNAL_LENGTH)
// or 1 to (OS2_HEADER_LENGTH - BFH_INTERNAL_LENGTH)
//
// But WIN_V3_HEADER_LENGTH =
// BFH_INTERNAL_LENGTH + WIN_V3_INTERNAL_BIH_LENGTH
// and OS2_HEADER_LENGTH = BFH_INTERNAL_LENGTH + OS2_INTERNAL_BIH_LENGTH
//
// So toCopy is in the range
//
// 1 to WIN_V3_INTERNAL_BIH_LENGTH
// or 1 to OS2_INTERNAL_BIH_LENGTH
// and OS2_INTERNAL_BIH_LENGTH < WIN_V3_INTERNAL_BIH_LENGTH
//
// sizeof(mRawBuf) = WIN_V3_INTERNAL_BIH_LENGTH
// so toCopy <= sizeof(mRawBuf)
uint32_t toCopy = mLOH - mPos;
if (toCopy > aCount) {
toCopy = aCount;
}
// mPos is in the range
// BFH_INTERNAL_LENGTH to (WIN_V3_HEADER_LENGTH - 1)
//
// offset is then in the range (see toCopy comments for more details)
// 0 to (WIN_V3_INTERNAL_BIH_LENGTH - 1)
//
// sizeof(mRawBuf) is WIN_V3_INTERNAL_BIH_LENGTH so this
// offset stays within bounds and this assert should hold
const uint32_t offset = mPos - BFH_INTERNAL_LENGTH;
MOZ_ASSERT(offset < sizeof(mRawBuf));
// Two cases:
// mPos = BFH_INTERNAL_LENGTH
// mLOH = WIN_V3_HEADER_LENGTH
//
// offset = 0
// toCopy = WIN_V3_INTERNAL_BIH_LENGTH
//
// This will be in the bounds of sizeof(mRawBuf)
//
// Second Case:
// mPos = WIN_V3_HEADER_LENGTH - 1
// mLOH = WIN_V3_HEADER_LENGTH
//
// offset = WIN_V3_INTERNAL_BIH_LENGTH - 1
// toCopy = 1
//
// This will be in the bounds of sizeof(mRawBuf)
//
// As sizeof(mRawBuf) == WIN_V3_INTERNAL_BIH_LENGTH (verified above)
// and WIN_V3_HEADER_LENGTH is the largest range of values. If mLOH
// was equal to OS2_HEADER_LENGTH then the ranges are smaller.
MOZ_ASSERT(offset + toCopy <= sizeof(mRawBuf));
memcpy(mRawBuf + offset, aBuffer, toCopy);
mPos += toCopy;
aCount -= toCopy;
aBuffer += toCopy;
}
// At this point mPos should be >= mLOH unless aBuffer did not have enough
// data. In the latter case aCount should be 0.
MOZ_ASSERT(mPos >= mLOH || aCount == 0);
// HasSize is called to ensure that if at this point mPos == mLOH but
// we have no data left to process, the next time WriteInternal is called
// we won't enter this condition again.
if (mPos == mLOH && !HasSize()) {
ProcessInfoHeader();
PR_LOG(GetBMPLog(), PR_LOG_DEBUG,
("BMP is %lix%lix%lu. compression=%lu\n",
mBIH.width, mBIH.height, mBIH.bpp, mBIH.compression));
// Verify we support this bit depth
if (mBIH.bpp != 1 && mBIH.bpp != 4 && mBIH.bpp != 8 &&
mBIH.bpp != 16 && mBIH.bpp != 24 && mBIH.bpp != 32) {
PostDataError();
return;
}
// BMPs with negative width are invalid
// Reject extremely wide images to keep the math sane
const int32_t k64KWidth = 0x0000FFFF;
if (mBIH.width < 0 || mBIH.width > k64KWidth) {
PostDataError();
return;
}
if (mBIH.height == INT_MIN) {
PostDataError();
return;
}
uint32_t real_height = GetHeight();
// Post our size to the superclass
PostSize(mBIH.width, real_height);
if (HasError()) {
// Setting the size led to an error.
return;
}
// We have the size. If we're doing a size decode, we got what
// we came for.
if (IsSizeDecode()) {
return;
}
// We're doing a real decode.
mOldLine = mCurLine = real_height;
if (mBIH.bpp <= 8) {
mNumColors = 1 << mBIH.bpp;
if (mBIH.colors && mBIH.colors < mNumColors) {
mNumColors = mBIH.colors;
}
// Always allocate 256 even though mNumColors might be smaller
mColors = new colorTable[256];
memset(mColors, 0, 256 * sizeof(colorTable));
} else if (mBIH.compression != BI_BITFIELDS && mBIH.bpp == 16) {
// Use default 5-5-5 format
mBitFields.red = 0x7C00;
mBitFields.green = 0x03E0;
mBitFields.blue = 0x001F;
CalcBitShift();
}
// Make sure we have a valid value for our supported compression modes
// before adding the frame
if (mBIH.compression != BI_RGB && mBIH.compression != BI_RLE8 &&
mBIH.compression != BI_RLE4 && mBIH.compression != BI_BITFIELDS) {
PostDataError();
return;
}
// If we have RLE4 or RLE8 or BI_ALPHABITFIELDS, then ensure we
// have valid BPP values before adding the frame
if (mBIH.compression == BI_RLE8 && mBIH.bpp != 8) {
PR_LOG(GetBMPLog(), PR_LOG_DEBUG,
("BMP RLE8 compression only supports 8 bits per pixel\n"));
PostDataError();
return;
}
if (mBIH.compression == BI_RLE4 && mBIH.bpp != 4 && mBIH.bpp != 1) {
PR_LOG(GetBMPLog(), PR_LOG_DEBUG,
("BMP RLE4 compression only supports 4 bits per pixel\n"));
PostDataError();
return;
}
if (mBIH.compression == BI_ALPHABITFIELDS &&
mBIH.bpp != 16 && mBIH.bpp != 32) {
PR_LOG(GetBMPLog(), PR_LOG_DEBUG,
("BMP ALPHABITFIELDS only supports 16 or 32 bits per pixel\n"
));
PostDataError();
return;
}
if (mBIH.compression != BI_RLE8 && mBIH.compression != BI_RLE4 &&
mBIH.compression != BI_ALPHABITFIELDS) {
// mRow is not used for RLE encoded images
mRow = (uint8_t*)moz_malloc((mBIH.width * mBIH.bpp) / 8 + 4);
// + 4 because the line is padded to a 4 bit boundary, but
// I don't want to make exact calculations here, that's unnecessary.
// Also, it compensates rounding error.
if (!mRow) {
PostDataError();
return;
}
}
if (!mImageData) {
PostDecoderError(NS_ERROR_FAILURE);
return;
}
// Prepare for transparency
if ((mBIH.compression == BI_RLE8) || (mBIH.compression == BI_RLE4)) {
// Clear the image, as the RLE may jump over areas
memset(mImageData, 0, mImageDataLength);
}
}
if (mColors && mPos >= mLOH) {
// OS/2 Bitmaps have no padding byte
uint8_t bytesPerColor = (mBFH.bihsize == OS2_BIH_LENGTH) ? 3 : 4;
if (mPos < (mLOH + mNumColors * bytesPerColor)) {
// Number of bytes already received
uint32_t colorBytes = mPos - mLOH;
// Color which is currently received
uint8_t colorNum = colorBytes / bytesPerColor;
uint8_t at = colorBytes % bytesPerColor;
while (aCount && (mPos < (mLOH + mNumColors * bytesPerColor))) {
switch (at) {
case 0:
mColors[colorNum].blue = *aBuffer;
break;
case 1:
mColors[colorNum].green = *aBuffer;
break;
case 2:
mColors[colorNum].red = *aBuffer;
// If there is no padding byte, increment the color index
// since we're done with the current color.
if (bytesPerColor == 3) {
colorNum++;
}
break;
case 3:
// This is a padding byte only in Windows BMPs. Increment
// the color index since we're done with the current color.
colorNum++;
break;
}
mPos++; aBuffer++; aCount--;
at = (at + 1) % bytesPerColor;
}
}
} else if (aCount && mBIH.compression == BI_BITFIELDS && mPos <
(WIN_V3_HEADER_LENGTH + BITFIELD_LENGTH)) {
// If compression is used, this is a windows bitmap (compression
// can't be used with OS/2 bitmaps),
// hence we can use WIN_V3_HEADER_LENGTH instead of mLOH.
// (verified below)
// If aCount != 0 then mPos should be >= mLOH due to the if statements
// at the beginning of the function
MOZ_ASSERT(mPos >= mLOH);
MOZ_ASSERT(mLOH == WIN_V3_HEADER_LENGTH);
// mLOH == WIN_V3_HEADER_LENGTH (verified above)
// mPos >= mLOH (verified above)
// mPos < WIN_V3_HEADER_LENGTH + BITFIELD_LENGTH
//
// So toCopy is in the range
// 0 to (BITFIELD_LENGTH - 1)
uint32_t toCopy = (WIN_V3_HEADER_LENGTH + BITFIELD_LENGTH) - mPos;
if (toCopy > aCount) {
toCopy = aCount;
}
// mPos >= WIN_V3_HEADER_LENGTH
// mPos < WIN_V3_HEADER_LENGTH + BITFIELD_LENGTH
//
// offset is in the range
// 0 to (BITFIELD_LENGTH - 1)
//
// BITFIELD_LENGTH < WIN_V3_INTERNAL_BIH_LENGTH
// and sizeof(mRawBuf) == WIN_V3_INTERNAL_BIH_LENGTH (verified at
// top of function)
//
// Therefore this assert should hold
const uint32_t offset = mPos - WIN_V3_HEADER_LENGTH;
MOZ_ASSERT(offset < sizeof(mRawBuf));
// Two cases:
// mPos = WIN_V3_HEADER_LENGTH
//
// offset = 0
// toCopy = BITFIELD_LENGTH
//
// This will be in the bounds of sizeof(mRawBuf)
//
// Second case:
//
// mPos = WIN_V3_HEADER_LENGTH + BITFIELD_LENGTH - 1
//
// offset = BITFIELD_LENGTH - 1
// toCopy = 1
//
// This will be in the bounds of sizeof(mRawBuf)
//
// As BITFIELD_LENGTH < WIN_V3_INTERNAL_BIH_LENGTH and
// sizeof(mRawBuf) == WIN_V3_INTERNAL_BIH_LENGTH
//
// Therefore this assert should hold
MOZ_ASSERT(offset + toCopy <= sizeof(mRawBuf));
memcpy(mRawBuf + offset, aBuffer, toCopy);
mPos += toCopy;
aBuffer += toCopy;
aCount -= toCopy;
}
if (mPos == WIN_V3_HEADER_LENGTH + BITFIELD_LENGTH &&
mBIH.compression == BI_BITFIELDS) {
mBitFields.red = LittleEndian::readUint32(reinterpret_cast<uint32_t*>
(mRawBuf));
mBitFields.green = LittleEndian::readUint32(reinterpret_cast<uint32_t*>
(mRawBuf + 4));
mBitFields.blue = LittleEndian::readUint32(reinterpret_cast<uint32_t*>
(mRawBuf + 8));
CalcBitShift();
}
while (aCount && (mPos < mBFH.dataoffset)) { // Skip whatever is between
// header and data
mPos++; aBuffer++; aCount--;
}
if (aCount && ++mPos >= mBFH.dataoffset) {
// Need to increment mPos, else we might get to mPos==mLOH again
// From now on, mPos is irrelevant
if (!mBIH.compression || mBIH.compression == BI_BITFIELDS) {
uint32_t rowSize = (mBIH.bpp * mBIH.width + 7) / 8; // + 7 to
// round up
if (rowSize % 4) {
rowSize += (4 - (rowSize % 4)); // Pad to DWORD Boundary
}
uint32_t toCopy;
do {
toCopy = rowSize - mRowBytes;
if (toCopy) {
if (toCopy > aCount) {
toCopy = aCount;
}
memcpy(mRow + mRowBytes, aBuffer, toCopy);
aCount -= toCopy;
aBuffer += toCopy;
mRowBytes += toCopy;
}
if (rowSize == mRowBytes) {
// Collected a whole row into mRow, process it
uint8_t* p = mRow;
uint32_t* d = reinterpret_cast<uint32_t*>(mImageData) +
PIXEL_OFFSET(mCurLine, 0);
uint32_t lpos = mBIH.width;
switch (mBIH.bpp) {
case 1:
while (lpos > 0) {
int8_t bit;
uint8_t idx;
for (bit = 7; bit >= 0 && lpos > 0; bit--) {
idx = (*p >> bit) & 1;
SetPixel(d, idx, mColors);
--lpos;
}
++p;
}
break;
case 4:
while (lpos > 0) {
Set4BitPixel(d, *p, lpos, mColors);
++p;
}
break;
case 8:
while (lpos > 0) {
SetPixel(d, *p, mColors);
--lpos;
++p;
}
break;
case 16:
while (lpos > 0) {
uint16_t val = LittleEndian::
readUint16(reinterpret_cast<uint16_t*>(p));
SetPixel(d,
(val & mBitFields.red) >>
mBitFields.redRightShift <<
mBitFields.redLeftShift,
(val & mBitFields.green) >>
mBitFields.greenRightShift <<
mBitFields.greenLeftShift,
(val & mBitFields.blue) >>
mBitFields.blueRightShift <<
mBitFields.blueLeftShift);
--lpos;
p+=2;
}
break;
case 24:
while (lpos > 0) {
SetPixel(d, p[2], p[1], p[0]);
p += 2;
--lpos;
++p;
}
break;
case 32:
while (lpos > 0) {
if (mUseAlphaData) {
if (!mHaveAlphaData && p[3]) {
// Non-zero alpha byte detected! Clear previous
// pixels that we have already processed.
// This works because we know that if we
// are reaching here then the alpha data in byte
// 4 has been right all along. And we know it
// has been set to 0 the whole time, so that
// means that everything is transparent so far.
uint32_t* start = reinterpret_cast<uint32_t*>
(mImageData) + GetWidth() *
(mCurLine - 1);
uint32_t heightDifference = GetHeight() -
mCurLine + 1;
uint32_t pixelCount = GetWidth() *
heightDifference;
memset(start, 0, pixelCount * sizeof(uint32_t));
PostHasTransparency();
mHaveAlphaData = true;
}
SetPixel(d, p[2], p[1], p[0], mHaveAlphaData ? p[3] : 0xFF);
} else {
SetPixel(d, p[2], p[1], p[0]);
}
p += 4;
--lpos;
}
break;
default:
NS_NOTREACHED("Unsupported color depth,"
" but earlier check didn't catch it");
}
mCurLine --;
if (mCurLine == 0) { // Finished last line
break;
}
mRowBytes = 0;
}
} while (aCount > 0);
} else if ((mBIH.compression == BI_RLE8) ||
(mBIH.compression == BI_RLE4)) {
if (((mBIH.compression == BI_RLE8) && (mBIH.bpp != 8)) ||
((mBIH.compression == BI_RLE4) && (mBIH.bpp != 4) &&
(mBIH.bpp != 1))) {
PR_LOG(GetBMPLog(), PR_LOG_DEBUG,
("BMP RLE8/RLE4 compression only supports 8/4 bits per"
" pixel\n"));
PostDataError();
return;
}
while (aCount > 0) {
uint8_t byte;
switch(mState) {
case eRLEStateInitial:
mStateData = (uint8_t)*aBuffer++;
aCount--;
mState = eRLEStateNeedSecondEscapeByte;
continue;
case eRLEStateNeedSecondEscapeByte:
byte = *aBuffer++;
aCount--;
if (mStateData != RLE_ESCAPE) { // encoded mode
// Encoded mode consists of two bytes:
// the first byte (mStateData) specifies the
// number of consecutive pixels to be drawn
// using the color index contained in
// the second byte
// Work around bitmaps that specify too many pixels
mState = eRLEStateInitial;
uint32_t pixelsNeeded = std::min<uint32_t>(mBIH.width - mCurPos,
mStateData);
if (pixelsNeeded) {
uint32_t* d = reinterpret_cast<uint32_t*>
(mImageData) + PIXEL_OFFSET(mCurLine, mCurPos);
mCurPos += pixelsNeeded;
if (mBIH.compression == BI_RLE8) {
do {
SetPixel(d, byte, mColors);
pixelsNeeded --;
} while (pixelsNeeded);
} else {
do {
Set4BitPixel(d, byte, pixelsNeeded, mColors);
} while (pixelsNeeded);
}
}
continue;
}
switch(byte) {
case RLE_ESCAPE_EOL:
// End of Line: Go to next row
mCurLine --;
mCurPos = 0;
mState = eRLEStateInitial;
break;
case RLE_ESCAPE_EOF: // EndOfFile
mCurPos = mCurLine = 0;
break;
case RLE_ESCAPE_DELTA:
mState = eRLEStateNeedXDelta;
continue;
default : // absolute mode
// Save the number of pixels to read
mStateData = byte;
if (mCurPos + mStateData > (uint32_t)mBIH.width) {
// We can work around bitmaps that specify
// one pixel too many, but only if their
// width is odd.
mStateData -= mBIH.width & 1;
if (mCurPos + mStateData > (uint32_t)mBIH.width) {
PostDataError();
return;
}
}
// See if we will need to skip a byte
// to word align the pixel data
// mStateData is a number of pixels
// so allow for the RLE compression type
// Pixels RLE8=1 RLE4=2
// 1 Pad Pad
// 2 No Pad
// 3 Pad No
// 4 No No
if (((mStateData - 1) & mBIH.compression) != 0) {
mState = eRLEStateAbsoluteMode;
} else {
mState = eRLEStateAbsoluteModePadded;
}
continue;
}
break;
case eRLEStateNeedXDelta:
// Handle the XDelta and proceed to get Y Delta
byte = *aBuffer++;
aCount--;
mCurPos += byte;
// Delta encoding makes it possible to skip pixels
// making the image transparent.
if (MOZ_UNLIKELY(!mHaveAlphaData)) {
PostHasTransparency();
}
mUseAlphaData = mHaveAlphaData = true;
if (mCurPos > mBIH.width) {
mCurPos = mBIH.width;
}
mState = eRLEStateNeedYDelta;
continue;
case eRLEStateNeedYDelta:
// Get the Y Delta and then "handle" the move
byte = *aBuffer++;
aCount--;
mState = eRLEStateInitial;
// Delta encoding makes it possible to skip pixels
// making the image transparent.
if (MOZ_UNLIKELY(!mHaveAlphaData)) {
PostHasTransparency();
}
mUseAlphaData = mHaveAlphaData = true;
mCurLine -= std::min<int32_t>(byte, mCurLine);
break;
case eRLEStateAbsoluteMode: // Absolute Mode
case eRLEStateAbsoluteModePadded:
if (mStateData) {
// In absolute mode, the second byte (mStateData)
// represents the number of pixels
// that follow, each of which contains
// the color index of a single pixel.
uint32_t* d = reinterpret_cast<uint32_t*>
(mImageData) +
PIXEL_OFFSET(mCurLine, mCurPos);
uint32_t* oldPos = d;
if (mBIH.compression == BI_RLE8) {
while (aCount > 0 && mStateData > 0) {
byte = *aBuffer++;
aCount--;
SetPixel(d, byte, mColors);
mStateData--;
}
} else {
while (aCount > 0 && mStateData > 0) {
byte = *aBuffer++;
aCount--;
Set4BitPixel(d, byte, mStateData, mColors);
}
}
mCurPos += d - oldPos;
}
if (mStateData == 0) {
// In absolute mode, each run must
// be aligned on a word boundary
if (mState == eRLEStateAbsoluteMode) {
// word aligned
mState = eRLEStateInitial;
} else if (aCount > 0) {
// not word aligned
// "next" byte is just a padding byte
// so "move" past it and we can continue
aBuffer++;
aCount--;
mState = eRLEStateInitial;
}
}
// else state is still eRLEStateAbsoluteMode
continue;
default :
NS_ABORT_IF_FALSE(0,
"BMP RLE decompression: unknown state!");
PostDecoderError(NS_ERROR_UNEXPECTED);
return;
}
// Because of the use of the continue statement
// we only get here for eol, eof or y delta
if (mCurLine == 0) {
// Finished last line
break;
}
}
}
}
const uint32_t rows = mOldLine - mCurLine;
if (rows) {
// Invalidate
nsIntRect r(0, mBIH.height < 0 ? -mBIH.height - mOldLine : mCurLine,
mBIH.width, rows);
PostInvalidation(r);
mOldLine = mCurLine;
}
return;
}
void
nsBMPDecoder::ProcessFileHeader()
{
memset(&mBFH, 0, sizeof(mBFH));
memcpy(&mBFH.signature, mRawBuf, sizeof(mBFH.signature));
memcpy(&mBFH.filesize, mRawBuf + 2, sizeof(mBFH.filesize));
memcpy(&mBFH.reserved, mRawBuf + 6, sizeof(mBFH.reserved));
memcpy(&mBFH.dataoffset, mRawBuf + 10, sizeof(mBFH.dataoffset));
memcpy(&mBFH.bihsize, mRawBuf + 14, sizeof(mBFH.bihsize));
// Now correct the endianness of the header
mBFH.filesize = LittleEndian::readUint32(&mBFH.filesize);
mBFH.dataoffset = LittleEndian::readUint32(&mBFH.dataoffset);
mBFH.bihsize = LittleEndian::readUint32(&mBFH.bihsize);
}
void
nsBMPDecoder::ProcessInfoHeader()
{
memset(&mBIH, 0, sizeof(mBIH));
if (mBFH.bihsize == 12) { // OS/2 Bitmap
memcpy(&mBIH.width, mRawBuf, 2);
memcpy(&mBIH.height, mRawBuf + 2, 2);
memcpy(&mBIH.planes, mRawBuf + 4, sizeof(mBIH.planes));
memcpy(&mBIH.bpp, mRawBuf + 6, sizeof(mBIH.bpp));
} else {
memcpy(&mBIH.width, mRawBuf, sizeof(mBIH.width));
memcpy(&mBIH.height, mRawBuf + 4, sizeof(mBIH.height));
memcpy(&mBIH.planes, mRawBuf + 8, sizeof(mBIH.planes));
memcpy(&mBIH.bpp, mRawBuf + 10, sizeof(mBIH.bpp));
memcpy(&mBIH.compression, mRawBuf + 12, sizeof(mBIH.compression));
memcpy(&mBIH.image_size, mRawBuf + 16, sizeof(mBIH.image_size));
memcpy(&mBIH.xppm, mRawBuf + 20, sizeof(mBIH.xppm));
memcpy(&mBIH.yppm, mRawBuf + 24, sizeof(mBIH.yppm));
memcpy(&mBIH.colors, mRawBuf + 28, sizeof(mBIH.colors));
memcpy(&mBIH.important_colors, mRawBuf + 32,
sizeof(mBIH.important_colors));
}
// Convert endianness
mBIH.width = LittleEndian::readUint32(&mBIH.width);
mBIH.height = LittleEndian::readUint32(&mBIH.height);
mBIH.planes = LittleEndian::readUint16(&mBIH.planes);
mBIH.bpp = LittleEndian::readUint16(&mBIH.bpp);
mBIH.compression = LittleEndian::readUint32(&mBIH.compression);
mBIH.image_size = LittleEndian::readUint32(&mBIH.image_size);
mBIH.xppm = LittleEndian::readUint32(&mBIH.xppm);
mBIH.yppm = LittleEndian::readUint32(&mBIH.yppm);
mBIH.colors = LittleEndian::readUint32(&mBIH.colors);
mBIH.important_colors = LittleEndian::readUint32(&mBIH.important_colors);
}
} // namespace image
} // namespace mozilla
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