Animated PNG implementation

third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.cpp

Index: third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.cpp
diff --git a/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.cpp b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.cpp
index 1aa5b1f62ec31626cce8f7f99840de72abfc0791..eff0a2bfbdd8f9c864395db240f4244784dda2ba 100644
--- a/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.cpp
+++ b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.cpp
@@ -50,10 +50,57 @@ PNGImageDecoder::PNGImageDecoder(AlphaOption alphaOption,
                                  size_t maxDecodedBytes,
                                  size_t offset)
     : ImageDecoder(alphaOption, colorOptions, maxDecodedBytes),
-      m_offset(offset) {}
+      m_offset(offset),
+      m_currentFrame(0) {}
 
 PNGImageDecoder::~PNGImageDecoder() {}
 
+bool PNGImageDecoder::frameIsCompleteAtIndex(size_t index) const {
+  if (!m_reader || failed())
+    return false;
+  if (m_frameBufferCache.size() <= 1)
+    return ImageDecoder::frameIsCompleteAtIndex(index);
+  bool frameIsLoadedAtIndex = index < m_frameBufferCache.size();
+  return frameIsLoadedAtIndex;
+}
+
+float PNGImageDecoder::frameDurationAtIndex(size_t index) const {
+  return (index < m_frameBufferCache.size())
+             ? m_frameBufferCache[index].duration()
+             : 0;
+}
+
+int PNGImageDecoder::repetitionCount() const {
+  return (!m_reader || failed()) ? cAnimationNone : m_reader->repetitionCount();
+}
+
+size_t PNGImageDecoder::clearCacheExceptFrame(size_t clearExceptFrame) {
+  if (clearExceptFrame >= m_frameBufferCache.size() ||
+      m_frameBufferCache.size() <= 1)
+    return 0;
+
+  size_t prevFrame = clearExceptFrame;
+  if (m_frameBufferCache[prevFrame].getDisposalMethod() ==
+      ImageFrame::DisposeOverwritePrevious)
+    prevFrame = m_frameBufferCache[prevFrame].requiredPreviousFrameIndex();
+
+  while (clearExceptFrame != kNotFound &&
+         m_frameBufferCache[clearExceptFrame].getStatus() !=
+             ImageFrame::FrameComplete) {
+    clearExceptFrame =
+        m_frameBufferCache[clearExceptFrame].requiredPreviousFrameIndex();
+  }
+
+  size_t frameBytesCleared = 0;
+  for (size_t i = 0; i < m_frameBufferCache.size(); ++i) {
+    if (i != prevFrame && i != clearExceptFrame) {
+      frameBytesCleared += frameBytesAtIndex(i);
+      clearFrameBuffer(i);
+    }
+  }
+  return frameBytesCleared;
+}
+
 inline float pngFixedToFloat(png_fixed_point x) {
   return ((float)x) * 0.00001f;
 }
@@ -111,22 +158,7 @@ inline sk_sp<SkColorSpace> readColorSpace(png_structp png, png_infop info) {
 void PNGImageDecoder::headerAvailable() {
   png_structp png = m_reader->pngPtr();
   png_infop info = m_reader->infoPtr();
-  png_uint_32 width = png_get_image_width(png, info);
-  png_uint_32 height = png_get_image_height(png, info);
-
-  // Protect against large PNGs. See http://bugzil.la/251381 for more details.
-  const unsigned long maxPNGSize = 1000000UL;
-  if (width > maxPNGSize || height > maxPNGSize) {
-    longjmp(JMPBUF(png), 1);
-    return;
-  }
-
-  // Set the image size now that the image header is available.
-  if (!setSize(width, height)) {
-    longjmp(JMPBUF(png), 1);
-    return;
-  }
-
+  png_uint_32 width, height;
   int bitDepth, colorType, interlaceType, compressionType, filterType, channels;
   png_get_IHDR(png, info, &width, &height, &bitDepth, &colorType,
                &interlaceType, &compressionType, &filterType);
@@ -200,19 +232,6 @@ void PNGImageDecoder::headerAvailable() {
   ASSERT(channels == 3 || channels == 4);
 
   m_reader->setHasAlpha(channels == 4);
-
-  if (m_reader->decodingSizeOnly()) {
-// If we only needed the size, halt the reader.
-#if PNG_LIBPNG_VER_MAJOR > 1 || \
-    (PNG_LIBPNG_VER_MAJOR == 1 && PNG_LIBPNG_VER_MINOR >= 5)
-    // Passing '0' tells png_process_data_pause() not to cache unprocessed data.
-    m_reader->setReadOffset(m_reader->currentBufferSize() -
-                            png_process_data_pause(png, 0));
-#else
-    m_reader->setReadOffset(m_reader->currentBufferSize() - png->buffer_size);
-    png->buffer_size = 0;
-#endif
-  }
 }
 
 void PNGImageDecoder::rowAvailable(unsigned char* rowBuffer,
@@ -222,7 +241,7 @@ void PNGImageDecoder::rowAvailable(unsigned char* rowBuffer,
     return;
 
   // Initialize the framebuffer if needed.
-  ImageFrame& buffer = m_frameBufferCache[0];
+  ImageFrame& buffer = m_frameBufferCache[m_currentFrame];
   if (buffer.getStatus() == ImageFrame::FrameEmpty) {
     png_structp png = m_reader->pngPtr();
     if (!buffer.setSizeAndColorSpace(size().width(), size().height(),
@@ -233,9 +252,12 @@ void PNGImageDecoder::rowAvailable(unsigned char* rowBuffer,
 
     unsigned colorChannels = m_reader->hasAlpha() ? 4 : 3;
     if (PNG_INTERLACE_ADAM7 ==
-        png_get_interlace_type(png, m_reader->infoPtr())) {
-      m_reader->createInterlaceBuffer(colorChannels * size().width() *
-                                      size().height());
+            png_get_interlace_type(png, m_reader->infoPtr()) ||
+        m_currentFrame) {
+      if (!m_reader->interlaceBuffer()) {
+        m_reader->createInterlaceBuffer(colorChannels * size().width() *
+                                        size().height());
+      }
       if (!m_reader->interlaceBuffer()) {
         longjmp(JMPBUF(png), 1);
         return;
@@ -245,8 +267,10 @@ void PNGImageDecoder::rowAvailable(unsigned char* rowBuffer,
     buffer.setStatus(ImageFrame::FramePartial);
     buffer.setHasAlpha(false);
 
-    // For PNGs, the frame always fills the entire image.
-    buffer.setOriginalFrameRect(IntRect(IntPoint(), size()));
+    if (!initFrameBuffer()) {
+      longjmp(JMPBUF(png), 1);
+      return;
+    }
   }
 
   /* libpng comments (here to explain what follows).
@@ -298,6 +322,10 @@ void PNGImageDecoder::rowAvailable(unsigned char* rowBuffer,
     png_progressive_combine_row(m_reader->pngPtr(), row, rowBuffer);
   }
 
+  // Only do incremental image display for the first frame.
+  if (m_currentFrame)
+    return;
+
   // Write the decoded row pixels to the frame buffer. The repetitive
   // form of the row write loops is for speed.
   ImageFrame::PixelData* const dstRow = buffer.getAddr(0, y);
@@ -363,28 +391,203 @@ void PNGImageDecoder::complete() {
   if (m_frameBufferCache.isEmpty())
     return;
 
-  m_frameBufferCache[0].setStatus(ImageFrame::FrameComplete);
+  ImageFrame& buffer = m_frameBufferCache[m_currentFrame];
+  buffer.setStatus(ImageFrame::FrameComplete);
+
+  if (!m_currentFrame)
+    return;
+
+  const IntRect& rect = buffer.originalFrameRect();
+  bool hasAlpha = m_reader->hasAlpha();
+  unsigned colorChannels = hasAlpha ? 4 : 3;
+  unsigned alphaMask = 255;
+  ImageFrame::AlphaBlendSource blendMethod = buffer.getAlphaBlendSource();
+
+  if (blendMethod == ImageFrame::BlendAtopPreviousFrame && !hasAlpha)
+    blendMethod = ImageFrame::BlendAtopBgcolor;
+
+  png_bytep row = m_reader->interlaceBuffer();
+  for (int y = rect.y(); y < rect.maxY();
+       ++y, row += colorChannels * size().width()) {
+    png_bytep srcPtr = row;
+    ImageFrame::PixelData* dstRow = buffer.getAddr(rect.x(), y);
+    if (hasAlpha) {
+      if (SkColorSpaceXform* xform = colorTransform()) {
+        SkColorSpaceXform::ColorFormat colorFormat =
+            SkColorSpaceXform::kRGBA_8888_ColorFormat;
+        xform->apply(colorFormat, srcPtr, colorFormat, srcPtr, rect.width(),
+                     kUnpremul_SkAlphaType);
+      }
+
+      if (blendMethod == ImageFrame::BlendAtopBgcolor) {
+        if (buffer.premultiplyAlpha()) {
+          for (auto *dstPixel = dstRow; dstPixel < dstRow + rect.width();
+               dstPixel++, srcPtr += 4) {
+            buffer.setRGBAPremultiply(dstPixel, srcPtr[0], srcPtr[1], srcPtr[2],
+                                      srcPtr[3]);
+            alphaMask &= srcPtr[3];
+          }
+        } else {
+          for (auto *dstPixel = dstRow; dstPixel < dstRow + rect.width();
+               dstPixel++, srcPtr += 4) {
+            buffer.setRGBARaw(dstPixel, srcPtr[0], srcPtr[1], srcPtr[2],
+                              srcPtr[3]);
+            alphaMask &= srcPtr[3];
+          }
+        }
+      } else {
+        if (buffer.premultiplyAlpha()) {
+          for (auto *dstPixel = dstRow; dstPixel < dstRow + rect.width();
+               dstPixel++, srcPtr += 4) {
+            buffer.overRGBAPremultiply(dstPixel, srcPtr[0], srcPtr[1],
+                                       srcPtr[2], srcPtr[3]);
+            alphaMask &= srcPtr[3];
+          }
+        } else {
+          for (auto *dstPixel = dstRow; dstPixel < dstRow + rect.width();
+               dstPixel++, srcPtr += 4) {
+            buffer.overRGBARaw(dstPixel, srcPtr[0], srcPtr[1], srcPtr[2],
+                               srcPtr[3]);
+            alphaMask &= srcPtr[3];
+          }
+        }
+      }
+    } else {
+      for (auto *dstPixel = dstRow; dstPixel < dstRow + rect.width();
+           dstPixel++, srcPtr += 3) {
+        buffer.setRGBARaw(dstPixel, srcPtr[0], srcPtr[1], srcPtr[2], 255);
+      }
+
+      if (SkColorSpaceXform* xform = colorTransform()) {
+        xform->apply(xformColorFormat(), dstRow, xformColorFormat(), dstRow,
+                     rect.width(), kOpaque_SkAlphaType);
+      }
+    }
+  }
+
+  if (alphaMask == 255) {
+    if (buffer.originalFrameRect().contains(IntRect(IntPoint(), size()))) {
+      buffer.setHasAlpha(false);
+    } else {
+      size_t frameIndex = m_currentFrame;
+      const ImageFrame* prevBuffer = &m_frameBufferCache[--frameIndex];
+      while (frameIndex && (prevBuffer->getDisposalMethod() ==
+                            ImageFrame::DisposeOverwritePrevious))
+        prevBuffer = &m_frameBufferCache[--frameIndex];
+      if ((prevBuffer->getDisposalMethod() ==
+           ImageFrame::DisposeOverwriteBgcolor) &&
+          !prevBuffer->hasAlpha() &&
+          buffer.originalFrameRect().contains(prevBuffer->originalFrameRect()))
+        buffer.setHasAlpha(false);
+    }
+  } else if (blendMethod == ImageFrame::BlendAtopBgcolor &&
+             !buffer.hasAlpha()) {
+    buffer.setHasAlpha(true);
+  }
 }
 
-inline bool isComplete(const PNGImageDecoder* decoder) {
-  return decoder->frameIsCompleteAtIndex(0);
+size_t PNGImageDecoder::decodeFrameCount() {
+  return parse() ? m_reader->imagesCount() : m_frameBufferCache.size();
 }
 
-void PNGImageDecoder::decode(bool onlySize) {
-  if (failed())
+void PNGImageDecoder::decode(size_t index) {
+  if (!m_reader || failed())
     return;
 
+  Vector<size_t> framesToDecode;
+  size_t frameToDecode = index;
+  do {
+    framesToDecode.append(frameToDecode);
+    frameToDecode =
+        m_frameBufferCache[frameToDecode].requiredPreviousFrameIndex();
+  } while (frameToDecode != kNotFound &&
+           m_frameBufferCache[frameToDecode].getStatus() !=
+               ImageFrame::FrameComplete);
+
+  for (auto i = framesToDecode.rbegin(); i != framesToDecode.rend(); ++i) {
+    m_currentFrame = *i;
+    if (!m_reader->decode(*m_data, m_currentFrame)) {
+      setFailed();
+      break;
+    }
+
+    // We need more data to continue decoding.
+    if (m_frameBufferCache[m_currentFrame].getStatus() !=
+        ImageFrame::FrameComplete)
+      break;
+  }
+}
+
+void PNGImageDecoder::initializeNewFrame(size_t index) {
+  ImageFrame* buffer = &m_frameBufferCache[index];
+  bool frameRectIsOpaque = buffer->getStatus() == ImageFrame::FrameComplete
+                               ? !m_reader->hasAlpha()
+                               : false;
+  buffer->setRequiredPreviousFrameIndex(
+      findRequiredPreviousFrame(index, frameRectIsOpaque));
+  const PNGImageReader::FrameInfo* frame = m_reader->frameInfo(index);
+  IntRect frameRect(frame->xOffset, frame->yOffset, frame->width,
+                    frame->height);
+  buffer->setOriginalFrameRect(
+      intersection(frameRect, IntRect(IntPoint(), size())));
+  buffer->setDuration(frame->duration);
+  buffer->setDisposalMethod(frame->dispose == 2
+                                ? ImageFrame::DisposeOverwritePrevious
+                                : frame->dispose == 1
+                                      ? ImageFrame::DisposeOverwriteBgcolor
+                                      : ImageFrame::DisposeKeep);
+  buffer->setAlphaBlendSource(frame->blend == 1
+                                  ? ImageFrame::BlendAtopPreviousFrame
+                                  : ImageFrame::BlendAtopBgcolor);
+}
+
+bool PNGImageDecoder::initFrameBuffer() {
+  ImageFrame& buffer = m_frameBufferCache[m_currentFrame];
+
+  const size_t requiredPreviousFrameIndex = buffer.requiredPreviousFrameIndex();
+  if (requiredPreviousFrameIndex == kNotFound) {
+    // This frame doesn't rely on any previous data.
+    buffer.zeroFillPixelData();
+    if (!m_currentFrame)
+      buffer.setHasAlpha(false);
+  } else {
+    ImageFrame& prevBuffer = m_frameBufferCache[requiredPreviousFrameIndex];
+    DCHECK(prevBuffer.getStatus() == ImageFrame::FrameComplete);
+
+    // Preserve the last frame as the starting state for this frame.
+    if (!buffer.takeBitmapDataIfWritable(&prevBuffer)) {
+      if (!buffer.copyBitmapData(prevBuffer))
+        return setFailed();
+    }
+
+    if (prevBuffer.getDisposalMethod() == ImageFrame::DisposeOverwriteBgcolor) {
+      // We want to clear the previous frame to transparent, without
+      // affecting pixels in the image outside of the frame.
+      const IntRect& prevRect = prevBuffer.originalFrameRect();
+      DCHECK(!prevRect.contains(IntRect(IntPoint(), size())));
+      buffer.zeroFillFrameRect(prevRect);
+    }
+  }
+  return true;
+}
+
+bool PNGImageDecoder::parse() {
+  if (failed())
+    return false;
+
   if (!m_reader)
     m_reader = wrapUnique(new PNGImageReader(this, m_offset));
 
   // If we couldn't decode the image but have received all the data, decoding
   // has failed.
-  if (!m_reader->decode(*m_data, onlySize) && isAllDataReceived())
+  if (!m_reader->parse(*m_data) && isAllDataReceived())
     setFailed();
 
-  // If decoding is done or failed, we don't need the PNGImageReader anymore.
-  if (isComplete(this) || failed())
+  if (failed()) {
     m_reader.reset();
+    return false;
+  }
+  return true;
 }
 
 }  // namespace blink