void
Decoder::Write(const char* aBuffer, uint32_t aCount)
{
  PROFILER_LABEL("ImageDecoder", "Write");

  // We're strict about decoder errors
  NS_ABORT_IF_FALSE(!HasDecoderError(),
                    "Not allowed to make more decoder calls after error!");

  // If a data error occured, just ignore future data
  if (HasDataError())
    return;

  if (IsSizeDecode() && HasSize()) {
    // More data came in since we found the size. We have nothing to do here.
    return;
  }

  // Pass the data along to the implementation
  WriteInternal(aBuffer, aCount);

  // If we're a synchronous decoder and we need a new frame to proceed, let's
  // create one and call it again.
  while (mSynchronous && NeedsNewFrame() && !HasDataError()) {
    nsresult rv = AllocateFrame();

    if (NS_SUCCEEDED(rv)) {
      // Tell the decoder to use the data it saved when it asked for a new frame.
      WriteInternal(nullptr, 0);
    }
  }
}

void
Decoder::PostFrameStop(FrameBlender::FrameAlpha aFrameAlpha /* = FrameBlender::kFrameHasAlpha */,
                       FrameBlender::FrameDisposalMethod aDisposalMethod /* = FrameBlender::kDisposeKeep */,
                       int32_t aTimeout /* = 0 */,
                       FrameBlender::FrameBlendMethod aBlendMethod /* = FrameBlender::kBlendOver */)
{
  // We should be mid-frame
  MOZ_ASSERT(!IsSizeDecode(), "Stopping frame during a size decode");
  MOZ_ASSERT(mInFrame, "Stopping frame when we didn't start one");
  MOZ_ASSERT(mCurrentFrame, "Stopping frame when we don't have one");

  // Update our state
  mInFrame = false;

  if (aFrameAlpha == FrameBlender::kFrameOpaque) {
    mCurrentFrame->SetHasNoAlpha();
  }

  mCurrentFrame->SetFrameDisposalMethod(aDisposalMethod);
  mCurrentFrame->SetRawTimeout(aTimeout);
  mCurrentFrame->SetBlendMethod(aBlendMethod);
  mCurrentFrame->ImageUpdated(mCurrentFrame->GetRect());

  mProgress |= FLAG_FRAME_COMPLETE | FLAG_ONLOAD_UNBLOCKED;
}

nsresult
nsIconDecoder::InitInternal()
{
  // Fire OnStartDecode at init time to support bug 512435
  if (!IsSizeDecode() && mObserver)
    mObserver->OnStartDecode(nsnull);

  return NS_OK;
}

nsresult
nsIconDecoder::FinishInternal()
{
  // If we haven't notified of completion yet for a full/success decode, we
  // didn't finish. Notify in error mode
  if (!IsSizeDecode() && !mNotifiedDone)
    NotifyDone(/* aSuccess = */ PR_FALSE);

  return NS_OK;
}

void
nsJPEGDecoder::FinishInternal()
{
  // If we're not in any sort of error case, force our state to JPEG_DONE.
  if ((mState != JPEG_DONE && mState != JPEG_SINK_NON_JPEG_TRAILER) &&
      (mState != JPEG_ERROR) &&
      !IsSizeDecode()) {
    mState = JPEG_DONE;
  }
}

void
Decoder::Write(const char* aBuffer, uint32_t aCount, DecodeStrategy aStrategy)
{
  PROFILER_LABEL("ImageDecoder", "Write",
    js::ProfileEntry::Category::GRAPHICS);

  MOZ_ASSERT(NS_IsMainThread() || aStrategy == DecodeStrategy::ASYNC);

  // We're strict about decoder errors
  MOZ_ASSERT(!HasDecoderError(),
             "Not allowed to make more decoder calls after error!");

  // Begin recording telemetry data.
  TimeStamp start = TimeStamp::Now();
  mChunkCount++;

  // Keep track of the total number of bytes written.
  mBytesDecoded += aCount;

  // If we're flushing data, clear the flag.
  if (aBuffer == nullptr && aCount == 0) {
    MOZ_ASSERT(mNeedsToFlushData, "Flushing when we don't need to");
    mNeedsToFlushData = false;
  }

  // If a data error occured, just ignore future data.
  if (HasDataError())
    return;

  if (IsSizeDecode() && HasSize()) {
    // More data came in since we found the size. We have nothing to do here.
    return;
  }

  // Pass the data along to the implementation
  WriteInternal(aBuffer, aCount, aStrategy);

  // If we're a synchronous decoder and we need a new frame to proceed, let's
  // create one and call it again.
  if (aStrategy == DecodeStrategy::SYNC) {
    while (NeedsNewFrame() && !HasDataError()) {
      nsresult rv = AllocateFrame();

      if (NS_SUCCEEDED(rv)) {
        // Use the data we saved when we asked for a new frame.
        WriteInternal(nullptr, 0, aStrategy);
      }

      mNeedsToFlushData = false;
    }
  }

  // Finish telemetry.
  mDecodeTime += (TimeStamp::Now() - start);
}

void
Decoder::PostDecodeDone(int32_t aLoopCount /* = 0 */)
{
  NS_ABORT_IF_FALSE(!IsSizeDecode(), "Can't be done with decoding with size decode!");
  NS_ABORT_IF_FALSE(!mInFrame, "Can't be done decoding if we're mid-frame!");
  NS_ABORT_IF_FALSE(!mDecodeDone, "Decode already done!");
  mDecodeDone = true;

  mImageMetadata.SetLoopCount(aLoopCount);

  mProgress |= FLAG_DECODE_COMPLETE;
}

void
Decoder::Finish()
{
  // Implementation-specific finalization
  if (!HasError())
    FinishInternal();

  // If the implementation left us mid-frame, finish that up.
  if (mInFrame && !HasDecoderError())
    PostFrameStop();

  // If PostDecodeDone() has not been called, we need to sent teardown
  // notifications.
  if (!IsSizeDecode() && !mDecodeDone) {

    // Log data errors to the error console
    nsCOMPtr<nsIConsoleService> consoleService =
      do_GetService(NS_CONSOLESERVICE_CONTRACTID);
    nsCOMPtr<nsIScriptError2> errorObject =
      do_CreateInstance(NS_SCRIPTERROR_CONTRACTID);

    if (consoleService && errorObject && !HasDecoderError()) {
      nsAutoString msg(NS_LITERAL_STRING("Image corrupt or truncated: ") +
                       NS_ConvertASCIItoUTF16(mImage->GetURIString()));

      errorObject->InitWithWindowID
        (msg.get(),
         NS_ConvertUTF8toUTF16(mImage->GetURIString()).get(),
         nsnull,
         0, 0, nsIScriptError::errorFlag,
         "Image", mImage->InnerWindowID()
         );
  
      nsCOMPtr<nsIScriptError> error = do_QueryInterface(errorObject);
      consoleService->LogMessage(error);
    }

    // If we only have a data error, see if things are worth salvaging
    bool salvage = !HasDecoderError() && mImage->GetNumFrames();

    // If we're salvaging, say we finished decoding
    if (salvage)
      mImage->DecodingComplete();

    // Fire teardown notifications
    if (mObserver) {
      mObserver->OnStopContainer(nsnull, mImage);
      mObserver->OnStopDecode(nsnull, salvage ? NS_OK : NS_ERROR_FAILURE, nsnull);
    }
  }
}

void
Decoder::Init()
{
  // No re-initializing
  NS_ABORT_IF_FALSE(!mInitialized, "Can't re-initialize a decoder!");

  // Fire OnStartDecode at init time to support bug 512435
  if (!IsSizeDecode() && mObserver)
      mObserver->OnStartDecode(nsnull);

  // Implementation-specific initialization
  InitInternal();
  mInitialized = true;
}

void
nsJPEGDecoder::FinishInternal()
{
  /* If we're not in any sort of error case, flush the decoder.
   *
   * XXXbholley - It seems wrong that this should be necessary, but at the
   * moment I'm just folding the contents of Flush() into Close() so that
   * we can get rid of it.
   */
  if ((mState != JPEG_DONE && mState != JPEG_SINK_NON_JPEG_TRAILER) &&
      (mState != JPEG_ERROR) &&
      !IsSizeDecode())
    this->Write(nullptr, 0);
}

void
Decoder::PostDecodeDone(int32_t aLoopCount /* = 0 */)
{
  NS_ABORT_IF_FALSE(!IsSizeDecode(), "Can't be done with decoding with size decode!");
  NS_ABORT_IF_FALSE(!mInFrame, "Can't be done decoding if we're mid-frame!");
  NS_ABORT_IF_FALSE(!mDecodeDone, "Decode already done!");
  mDecodeDone = true;

  mImageMetadata.SetLoopCount(aLoopCount);
  mImageMetadata.SetIsNonPremultiplied(GetDecodeFlags() & DECODER_NO_PREMULTIPLY_ALPHA);

  if (mObserver) {
    mObserver->OnStopDecode(NS_OK);
  }
}

void
nsWEBPDecoder::FinishInternal()
{
  // Flush the Decoder and let it free the output image buffer.
  WebPIDelete(mDecoder);
  WebPFreeDecBuffer(&mDecBuf);

  // We should never make multiple frames
  MOZ_ASSERT(GetFrameCount() <= 1, "Multiple WebP frames?");

  // Send notifications if appropriate
  if (!IsSizeDecode() && (GetFrameCount() == 1)) {
    PostFrameStop();
    PostDecodeDone();
  }
}

void
nsJPEGDecoder::FinishInternal()
{
  /* If we're not in any sort of error case, flush the decoder.
   *
   * XXXbholley - It seems wrong that this should be necessary, but at the
   * moment I'm just folding the contents of Flush() into Close() so that
   * we can get rid of it.
   *
   * XXX(seth): It'd be great to get rid of this. For now, we treat this as a
   * write to a synchronous decoder, which means that this must be called only
   * on the main thread. (That's asserted in Decoder::Finish and
   * Decoder::FinishSharedDecoder.)
   */
  if ((mState != JPEG_DONE && mState != JPEG_SINK_NON_JPEG_TRAILER) &&
      (mState != JPEG_ERROR) &&
      !IsSizeDecode())
    this->Write(nullptr, 0, DECODE_SYNC);
}

void
Decoder::Init(RasterImage* aImage, imgIDecoderObserver* aObserver)
{
  // We should always have an image
  NS_ABORT_IF_FALSE(aImage, "Can't initialize decoder without an image!");

  // No re-initializing
  NS_ABORT_IF_FALSE(mImage == nsnull, "Can't re-initialize a decoder!");

  // Save our paremeters
  mImage = aImage;
  mObserver = aObserver;

  // Fire OnStartDecode at init time to support bug 512435
  if (!IsSizeDecode() && mObserver)
      mObserver->OnStartDecode(nsnull);

  // Implementation-specific initialization
  InitInternal();
  mInitialized = true;
}

void
Decoder::PostDecodeDone()
{
  NS_ABORT_IF_FALSE(!IsSizeDecode(), "Can't be done with decoding with size decode!");
  NS_ABORT_IF_FALSE(!mInFrame, "Can't be done decoding if we're mid-frame!");
  NS_ABORT_IF_FALSE(!mDecodeDone, "Decode already done!");
  mDecodeDone = true;

  // Set premult before DecodingComplete(), since DecodingComplete() calls Optimize()
  int frames = GetFrameCount();
  bool isNonPremult = GetDecodeFlags() & DECODER_NO_PREMULTIPLY_ALPHA;
  for (int i = 0; i < frames; i++) {
    mImage.SetFrameAsNonPremult(i, isNonPremult);
  }

  // Notify
  mImage.DecodingComplete();
  if (mObserver) {
    mObserver->OnStopContainer(nsnull, &mImage);
    mObserver->OnStopDecode(nsnull, NS_OK, nsnull);
  }
}

void
nsPNGDecoder::WriteInternal(const char* aBuffer, uint32_t aCount)
{
  MOZ_ASSERT(!HasError(), "Shouldn't call WriteInternal after error!");

  // If we only want width/height, we don't need to go through libpng
  if (IsSizeDecode()) {

    // Are we done?
    if (mHeaderBytesRead == BYTES_NEEDED_FOR_DIMENSIONS) {
      return;
    }

    // Scan the header for the width and height bytes
    uint32_t pos = 0;
    const uint8_t* bptr = (uint8_t*)aBuffer;

    while (pos < aCount && mHeaderBytesRead < BYTES_NEEDED_FOR_DIMENSIONS) {
      // Verify the signature bytes
      if (mHeaderBytesRead < sizeof(pngSignatureBytes)) {
        if (bptr[pos] != nsPNGDecoder::pngSignatureBytes[mHeaderBytesRead]) {
          PostDataError();
          return;
        }
      }

      // Get width and height bytes into the buffer
      if ((mHeaderBytesRead >= WIDTH_OFFSET) &&
          (mHeaderBytesRead < BYTES_NEEDED_FOR_DIMENSIONS)) {
        mSizeBytes[mHeaderBytesRead - WIDTH_OFFSET] = bptr[pos];
      }
      pos ++;
      mHeaderBytesRead ++;
    }

    // If we're done now, verify the data and set up the container
    if (mHeaderBytesRead == BYTES_NEEDED_FOR_DIMENSIONS) {

      // Grab the width and height, accounting for endianness (thanks libpng!)
      uint32_t width = png_get_uint_32(mSizeBytes);
      uint32_t height = png_get_uint_32(mSizeBytes + 4);

      // Too big?
      if ((width > MOZ_PNG_MAX_DIMENSION) || (height > MOZ_PNG_MAX_DIMENSION)) {
        PostDataError();
        return;
      }

      // Post our size to the superclass
      PostSize(width, height);
    }

  // Otherwise, we're doing a standard decode
  } else {

    // libpng uses setjmp/longjmp for error handling - set the buffer
    if (setjmp(png_jmpbuf(mPNG))) {

      // We might not really know what caused the error, but it makes more
      // sense to blame the data.
      if (!HasError()) {
        PostDataError();
      }

      png_destroy_read_struct(&mPNG, &mInfo, nullptr);
      return;
    }

    // Pass the data off to libpng
    png_process_data(mPNG, mInfo, (unsigned char*)aBuffer, aCount);

  }
}

void
nsJPEGDecoder::WriteInternal(const char* aBuffer, uint32_t aCount,
                             DecodeStrategy)
{
  mSegment = (const JOCTET*)aBuffer;
  mSegmentLen = aCount;

  NS_ABORT_IF_FALSE(!HasError(), "Shouldn't call WriteInternal after error!");

  // Return here if there is a fatal error within libjpeg.
  nsresult error_code;
  // This cast to nsresult makes sense because setjmp() returns whatever we
  // passed to longjmp(), which was actually an nsresult.
  if ((error_code = (nsresult)setjmp(mErr.setjmp_buffer)) != NS_OK) {
    if (error_code == NS_ERROR_FAILURE) {
      PostDataError();
      // Error due to corrupt stream - return NS_OK and consume silently
      // so that ImageLib doesn't throw away a partial image load
      mState = JPEG_SINK_NON_JPEG_TRAILER;
      PR_LOG(GetJPEGDecoderAccountingLog(), PR_LOG_DEBUG,
             ("} (setjmp returned NS_ERROR_FAILURE)"));
      return;
    } else {
      // Error due to reasons external to the stream (probably out of
      // memory) - let ImageLib attempt to clean up, even though
      // mozilla is seconds away from falling flat on its face.
      PostDecoderError(error_code);
      mState = JPEG_ERROR;
      PR_LOG(GetJPEGDecoderAccountingLog(), PR_LOG_DEBUG,
             ("} (setjmp returned an error)"));
      return;
    }
  }

  PR_LOG(GetJPEGLog(), PR_LOG_DEBUG,
         ("[this=%p] nsJPEGDecoder::Write -- processing JPEG data\n", this));

  switch (mState) {
    case JPEG_HEADER: {
      LOG_SCOPE(GetJPEGLog(), "nsJPEGDecoder::Write -- entering JPEG_HEADER"
                " case");

      // Step 3: read file parameters with jpeg_read_header()
      if (jpeg_read_header(&mInfo, TRUE) == JPEG_SUSPENDED) {
        PR_LOG(GetJPEGDecoderAccountingLog(), PR_LOG_DEBUG,
               ("} (JPEG_SUSPENDED)"));
        return; // I/O suspension
      }

      int sampleSize = mImage.GetRequestedSampleSize();
      if (sampleSize > 0) {
        mInfo.scale_num = 1;
        mInfo.scale_denom = sampleSize;
      }

      // Used to set up image size so arrays can be allocated
      jpeg_calc_output_dimensions(&mInfo);

      // Post our size to the superclass
      PostSize(mInfo.output_width, mInfo.output_height,
               ReadOrientationFromEXIF());
      if (HasError()) {
        // Setting the size led to an error.
        mState = JPEG_ERROR;
        return;
      }

      // If we're doing a size decode, we're done.
      if (IsSizeDecode()) {
        return;
      }

      // We're doing a full decode.
      if (mCMSMode != eCMSMode_Off &&
          (mInProfile = GetICCProfile(mInfo)) != nullptr) {
        uint32_t profileSpace = qcms_profile_get_color_space(mInProfile);
        bool mismatch = false;

#ifdef DEBUG_tor
      fprintf(stderr, "JPEG profileSpace: 0x%08X\n", profileSpace);
#endif
      switch (mInfo.jpeg_color_space) {
        case JCS_GRAYSCALE:
          if (profileSpace == icSigRgbData) {
            mInfo.out_color_space = JCS_RGB;
          } else if (profileSpace != icSigGrayData) {
            mismatch = true;
          }
          break;
        case JCS_RGB:
          if (profileSpace != icSigRgbData) {
            mismatch =  true;
          }
          break;
        case JCS_YCbCr:
          if (profileSpace == icSigRgbData) {
            mInfo.out_color_space = JCS_RGB;
          } else {
            // qcms doesn't support ycbcr
            mismatch = true;
//.........这里部分代码省略.........

//.........这里部分代码省略.........
        mGIFStruct.suffix[i] = i;

      mGIFStruct.stackp = mGIFStruct.stack;

      GETN(1, gif_sub_block);
    }
    break;

    /* All GIF files begin with "GIF87a" or "GIF89a" */
    case gif_type:
      if (!strncmp((char*)q, "GIF89a", 6)) {
        mGIFStruct.version = 89;
      } else if (!strncmp((char*)q, "GIF87a", 6)) {
        mGIFStruct.version = 87;
      } else {
        mGIFStruct.state = gif_error;
        break;
      }
      GETN(7, gif_global_header);
      break;

    case gif_global_header:
      /* This is the height and width of the "screen" or
       * frame into which images are rendered.  The
       * individual images can be smaller than the
       * screen size and located with an origin anywhere
       * within the screen.
       */

      mGIFStruct.screen_width = GETINT16(q);
      mGIFStruct.screen_height = GETINT16(q + 2);
      mGIFStruct.global_colormap_depth = (q[4]&0x07) + 1;

      if (IsSizeDecode()) {
        MOZ_ASSERT(!mGIFOpen, "Gif should not be open at this point");
        PostSize(mGIFStruct.screen_width, mGIFStruct.screen_height);
        return;
      }

      // screen_bgcolor is not used
      //mGIFStruct.screen_bgcolor = q[5];
      // q[6] = Pixel Aspect Ratio
      //   Not used
      //   float aspect = (float)((q[6] + 15) / 64.0);

      if (q[4] & 0x80) { /* global map */
        // Get the global colormap
        const uint32_t size = (3 << mGIFStruct.global_colormap_depth);
        if (len < size) {
          // Use 'hold' pattern to get the global colormap
          GETN(size, gif_global_colormap);
          break;
        }
        // Copy everything, go to colormap state to do CMS correction
        memcpy(mGIFStruct.global_colormap, buf, size);
        buf += size;
        len -= size;
        GETN(0, gif_global_colormap);
        break;
      }

      GETN(1, gif_image_start);
      break;

    case gif_global_colormap:
      // Everything is already copied into global_colormap

void
Decoder::Finish(RasterImage::eShutdownIntent aShutdownIntent)
{
  // Implementation-specific finalization
  if (!HasError())
    FinishInternal();

  // If the implementation left us mid-frame, finish that up.
  if (mInFrame && !HasError())
    PostFrameStop();

  // If PostDecodeDone() has not been called, we need to sent teardown
  // notifications.
  if (!IsSizeDecode() && !mDecodeDone) {

    // Log data errors to the error console
    nsCOMPtr<nsIConsoleService> consoleService =
      do_GetService(NS_CONSOLESERVICE_CONTRACTID);
    nsCOMPtr<nsIScriptError> errorObject =
      do_CreateInstance(NS_SCRIPTERROR_CONTRACTID);

    if (consoleService && errorObject && !HasDecoderError()) {
      nsAutoString msg(NS_LITERAL_STRING("Image corrupt or truncated: ") +
                       NS_ConvertUTF8toUTF16(mImage.GetURIString()));

      if (NS_SUCCEEDED(errorObject->InitWithWindowID(
                         msg,
                         NS_ConvertUTF8toUTF16(mImage.GetURIString()),
                         EmptyString(), 0, 0, nsIScriptError::errorFlag,
                         "Image", mImage.InnerWindowID()
                       ))) {
        consoleService->LogMessage(errorObject);
      }
    }

    bool usable = true;
    if (aShutdownIntent != RasterImage::eShutdownIntent_NotNeeded && !HasDecoderError()) {
      // If we only have a data error, we're usable if we have at least one complete frame.
      if (GetCompleteFrameCount() == 0) {
        usable = false;
      }
    }

    // If we're usable, do exactly what we should have when the decoder
    // completed.
    if (usable) {
      if (mInFrame) {
        PostFrameStop();
      }
      PostDecodeDone();
    } else {
      if (mObserver) {
        mObserver->OnStopDecode(NS_ERROR_FAILURE);
      }
    }
  }

  // Set image metadata before calling DecodingComplete, because DecodingComplete calls Optimize().
  mImageMetadata.SetOnImage(&mImage);

  if (mDecodeDone) {
    mImage.DecodingComplete();
  }
}

void
nsIconDecoder::WriteInternal(const char* aBuffer, uint32_t aCount,
                             DecodeStrategy)
{
  NS_ABORT_IF_FALSE(!HasError(), "Shouldn't call WriteInternal after error!");

  // We put this here to avoid errors about crossing initialization with case
  // jumps on linux.
  uint32_t bytesToRead = 0;

  // Loop until the input data is gone
  while (aCount > 0) {
    switch (mState) {
      case iconStateStart:

        // Grab the width
        mWidth = (uint8_t)*aBuffer;

        // Book Keeping
        aBuffer++;
        aCount--;
        mState = iconStateHaveHeight;
        break;

      case iconStateHaveHeight:

        // Grab the Height
        mHeight = (uint8_t)*aBuffer;

        // Post our size to the superclass
        PostSize(mWidth, mHeight);

        PostHasTransparency();

        if (HasError()) {
          // Setting the size led to an error.
          mState = iconStateFinished;
          return;
        }

        // If We're doing a size decode, we're done
        if (IsSizeDecode()) {
          mState = iconStateFinished;
          break;
        }

        if (!mImageData) {
          PostDecoderError(NS_ERROR_OUT_OF_MEMORY);
          return;
        }

        // Book Keeping
        aBuffer++;
        aCount--;
        mState = iconStateReadPixels;
        break;

      case iconStateReadPixels: {

        // How many bytes are we reading?
        bytesToRead = std::min(aCount, mImageDataLength - mPixBytesRead);

        // Copy the bytes
        memcpy(mImageData + mPixBytesRead, aBuffer, bytesToRead);

        // Performance isn't critical here, so our update rectangle is
        // always the full icon
        nsIntRect r(0, 0, mWidth, mHeight);

        // Invalidate
        PostInvalidation(r);

        // Book Keeping
        aBuffer += bytesToRead;
        aCount -= bytesToRead;
        mPixBytesRead += bytesToRead;

        // If we've got all the pixel bytes, we're finished
        if (mPixBytesRead == mImageDataLength) {
          PostFrameStop();
          PostDecodeDone();
          mState = iconStateFinished;
        }
        break;
      }

      case iconStateFinished:

        // Consume all excess data silently
        aCount = 0;

        break;
    }
  }
}