mirror of
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280 lines
8.5 KiB
C++
280 lines
8.5 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "nsWBMPDecoder.h"
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#include "RasterImage.h"
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#include "nspr.h"
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#include "nsRect.h"
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#include "gfxPlatform.h"
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#include "nsError.h"
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namespace mozilla {
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namespace image {
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static inline void SetPixel(uint32_t*& aDecoded, bool aPixelWhite)
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{
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uint8_t pixelValue = aPixelWhite ? 255 : 0;
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*aDecoded++ = gfxPackedPixel(0xFF, pixelValue, pixelValue, pixelValue);
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}
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/** Parses a WBMP encoded int field. Returns IntParseInProgress (out of
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* data), IntParseSucceeded if the field was read OK or IntParseFailed
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* on an error.
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* The encoding used for WBMP ints is per byte. The high bit is a
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* continuation flag saying (when set) that the next byte is part of the
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* field, and the low seven bits are data. New data bits are added in the
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* low bit positions, i.e. the field is big-endian (ignoring the high bits).
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* @param aField Variable holds current value of field. When this function
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* returns IntParseInProgress, aField will hold the
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* intermediate result of the decoding, so this function can be
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* called repeatedly for new bytes on the same field and will
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* operate correctly.
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* @param aBuffer Points to encoded field data.
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* @param aCount Number of bytes in aBuffer. */
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static WbmpIntDecodeStatus DecodeEncodedInt (uint32_t& aField, const char*& aBuffer, uint32_t& aCount)
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{
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while (aCount > 0) {
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// Check if the result would overflow if another seven bits were added.
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// The actual test performed is AND to check if any of the top seven bits are set.
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if (aField & 0xFE000000) {
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// Overflow :(
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return IntParseFailed;
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}
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// Get next encoded byte.
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char encodedByte = *aBuffer;
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// Update buffer state variables now we have read this byte.
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aBuffer++;
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aCount--;
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// Work out and store the new (valid) value of the encoded int with this byte added.
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aField = (aField << 7) + (uint32_t)(encodedByte & 0x7F);
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if (!(encodedByte & 0x80)) {
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// No more bytes, value is complete.
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return IntParseSucceeded;
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}
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}
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// Out of data but in the middle of an encoded int.
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return IntParseInProgress;
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}
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nsWBMPDecoder::nsWBMPDecoder(RasterImage &aImage)
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: Decoder(aImage),
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mWidth(0),
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mHeight(0),
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mRow(nullptr),
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mRowBytes(0),
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mCurLine(0),
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mState(WbmpStateStart)
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{
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// Nothing to do
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}
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nsWBMPDecoder::~nsWBMPDecoder()
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{
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moz_free(mRow);
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}
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void
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nsWBMPDecoder::WriteInternal(const char *aBuffer, uint32_t aCount)
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{
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NS_ABORT_IF_FALSE(!HasError(), "Shouldn't call WriteInternal after error!");
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// Loop until the input data is gone
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while (aCount > 0) {
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switch (mState) {
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case WbmpStateStart:
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{
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// Since we only accept a type 0 WBMP we can just check the first byte is 0.
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// (The specification says a well defined type 0 bitmap will start with a 0x00 byte).
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if (*aBuffer++ == 0x00) {
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// This is a type 0 WBMP.
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aCount--;
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mState = DecodingFixHeader;
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} else {
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// This is a new type of WBMP or a type 0 WBMP defined oddly (e.g. 0x80 0x00)
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PostDataError();
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mState = DecodingFailed;
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return;
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}
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break;
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}
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case DecodingFixHeader:
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{
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if ((*aBuffer++ & 0x9F) == 0x00) {
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// Fix header field is as expected
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aCount--;
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// For now, we skip the ext header field as it is not in a well-defined type 0 WBMP.
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mState = DecodingWidth;
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} else {
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// Can't handle this fix header field.
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PostDataError();
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mState = DecodingFailed;
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return;
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}
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break;
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}
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case DecodingWidth:
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{
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WbmpIntDecodeStatus widthReadResult = DecodeEncodedInt (mWidth, aBuffer, aCount);
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if (widthReadResult == IntParseSucceeded) {
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mState = DecodingHeight;
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} else if (widthReadResult == IntParseFailed) {
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// Encoded width was bigger than a uint32_t or equal to 0.
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PostDataError();
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mState = DecodingFailed;
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return;
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} else {
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// We are still parsing the encoded int field.
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NS_ABORT_IF_FALSE((widthReadResult == IntParseInProgress),
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"nsWBMPDecoder got bad result from an encoded width field");
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return;
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}
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break;
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}
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case DecodingHeight:
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{
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WbmpIntDecodeStatus heightReadResult = DecodeEncodedInt (mHeight, aBuffer, aCount);
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if (heightReadResult == IntParseSucceeded) {
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// The header has now been entirely read.
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const uint32_t k64KWidth = 0x0000FFFF;
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if (mWidth == 0 || mWidth > k64KWidth
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|| mHeight == 0 || mHeight > k64KWidth) {
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// consider 0 as an incorrect image size
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// reject the extremely wide/high images to keep the math sane
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PostDataError();
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mState = DecodingFailed;
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return;
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}
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// Post our size to the superclass
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PostSize(mWidth, mHeight);
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if (HasError()) {
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// Setting the size led to an error.
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mState = DecodingFailed;
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return;
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}
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// If We're doing a size decode, we're done
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if (IsSizeDecode()) {
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mState = WbmpStateFinished;
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return;
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}
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if (!mImageData) {
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PostDecoderError(NS_ERROR_FAILURE);
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mState = DecodingFailed;
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return;
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}
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// Create mRow, the buffer that holds one line of the raw image data
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mRow = (uint8_t*)moz_malloc((mWidth + 7) / 8);
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if (!mRow) {
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PostDecoderError(NS_ERROR_OUT_OF_MEMORY);
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mState = DecodingFailed;
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return;
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}
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mState = DecodingImageData;
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} else if (heightReadResult == IntParseFailed) {
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// Encoded height was bigger than a uint32_t.
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PostDataError();
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mState = DecodingFailed;
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return;
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} else {
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// We are still parsing the encoded int field.
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NS_ABORT_IF_FALSE((heightReadResult == IntParseInProgress),
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"nsWBMPDecoder got bad result from an encoded height field");
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return;
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}
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break;
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}
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case DecodingImageData:
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{
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uint32_t rowSize = (mWidth + 7) / 8; // +7 to round up to nearest byte
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uint32_t top = mCurLine;
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// Process up to one row of data at a time until there is no more data.
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while ((aCount > 0) && (mCurLine < mHeight)) {
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// Calculate if we need to copy data to fill the next buffered row of raw data.
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uint32_t toCopy = rowSize - mRowBytes;
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// If required, copy raw data to fill a buffered row of raw data.
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if (toCopy) {
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if (toCopy > aCount)
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toCopy = aCount;
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memcpy(mRow + mRowBytes, aBuffer, toCopy);
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aCount -= toCopy;
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aBuffer += toCopy;
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mRowBytes += toCopy;
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}
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// If there is a filled buffered row of raw data, process the row.
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if (rowSize == mRowBytes) {
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uint8_t *p = mRow;
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uint32_t *d = reinterpret_cast<uint32_t*>(mImageData) + (mWidth * mCurLine); // position of the first pixel at mCurLine
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uint32_t lpos = 0;
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while (lpos < mWidth) {
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for (int8_t bit = 7; bit >= 0; bit--) {
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if (lpos >= mWidth)
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break;
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bool pixelWhite = (*p >> bit) & 1;
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SetPixel(d, pixelWhite);
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++lpos;
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}
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++p;
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}
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mCurLine++;
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mRowBytes = 0;
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}
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}
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nsIntRect r(0, top, mWidth, mCurLine - top);
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// Invalidate
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PostInvalidation(r);
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// If we've got all the pixel bytes, we're finished
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if (mCurLine == mHeight) {
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PostFrameStop();
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PostDecodeDone();
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mState = WbmpStateFinished;
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}
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break;
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}
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case WbmpStateFinished:
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{
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// Consume all excess data silently
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aCount = 0;
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break;
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}
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case DecodingFailed:
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{
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NS_ABORT_IF_FALSE(0, "Shouldn't process any data after decode failed!");
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return;
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}
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}
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}
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}
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} // namespace image
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} // namespace mozilla
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