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Bug 1290293 - Part 2b. Make nsBMPDecoder explicitly write transparent pixels for those skipped by delta encoding. r=tnikkel

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This commit is contained in:
Andrew Osmond 2017-02-13 19:51:40 -05:00
parent b5f1768cea
commit bd54fc7365
1 changed files with 19 additions and 16 deletions
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35
image/decoders/nsBMPDecoder.cpp
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@ -994,33 +994,36 @@ nsBMPDecoder::ReadRLEDelta(const char* aData)
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 XDelta. This clears to the end of the row, which
// which is perfect if there's a Y delta and harmless if not.
uint8_t xDelta = uint8_t(aData[0]);
int32_t finalPos = std::min<int32_t>(mH.mWidth, mCurrentPos + xDelta);
uint32_t* dst = RowBuffer();
while (mCurrentPos < mH.mWidth) {
SetPixel(dst, 0, 0, 0, 0);
++mCurrentPos;
}
// Handle the Y Delta.
int32_t yDelta = std::min<int32_t>(uint8_t(aData[1]), mCurrentRow);
mCurrentRow -= yDelta;
if (mDownscaler && yDelta > 0) {
if (yDelta > 0) {
// Commit the current row (the first of the skipped rows).
mDownscaler->CommitRow();
mCurrentPos = 0;
FinishRow();
// Clear and commit the remaining skipped rows.
for (int32_t line = 1; line < yDelta; line++) {
mDownscaler->ClearRow();
mDownscaler->CommitRow();
dst = RowBuffer();
while (mCurrentPos < mH.mWidth) {
SetPixel(dst, 0, 0, 0, 0);
++mCurrentPos;
}
mCurrentPos = 0;
FinishRow();
}
}
mCurrentPos = finalPos;
return mCurrentRow == 0
? Transition::TerminateSuccess()
: Transition::To(State::RLE_SEGMENT, RLE::SEGMENT_LENGTH);