Move gif image decoder to SkCodec

third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.cpp

Index: third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.cpp
diff --git a/third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.cpp b/third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.cpp
index 25a00e19e67b15afea346b667c28500d2a13b27d..d98538837f5deffb6d1d4c3f2634dab33fe20dca 100644
--- a/third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.cpp
+++ b/third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.cpp
@@ -26,9 +26,9 @@
 #include "platform/image-decoders/gif/GIFImageDecoder.h"
 
 #include <limits>
-#include "platform/image-decoders/gif/GIFImageReader.h"
 #include "platform/wtf/NotFound.h"
 #include "platform/wtf/PtrUtil.h"
+#include "third_party/skia/include/core/SkImageInfo.h"
 
 namespace blink {
 
@@ -36,247 +36,252 @@ GIFImageDecoder::GIFImageDecoder(AlphaOption alpha_option,
                                  const ColorBehavior& color_behavior,
                                  size_t max_decoded_bytes)
     : ImageDecoder(alpha_option, color_behavior, max_decoded_bytes),
-      repetition_count_(kCAnimationLoopOnce) {}
-
-GIFImageDecoder::~GIFImageDecoder() {}
+      codec_(),
+      segment_stream_(nullptr),
+      frame_infos_() {}
+
+GIFImageDecoder::~GIFImageDecoder() {
+  if (!codec_) {
+    // if we did not create |codec_| and thus did not pass ownership to it
+    if (segment_stream_)
+      delete segment_stream_;
+  }
+}
 
 void GIFImageDecoder::OnSetData(SegmentReader* data) {
-  if (reader_)
-    reader_->setData(data);
+  if (!data) {
+    if (segment_stream_)
+      segment_stream_->SetReader(nullptr);
+    return;
+  }
+
+  if (!segment_stream_)
+    segment_stream_ = new SegmentStream();
+
+  segment_stream_->SetReader(data);
+
+  if (!codec_) {
+    codec_.reset(SkCodec::NewFromStream(segment_stream_, nullptr));
+    if (!codec_) {
+      // |segment_stream_|'s ownership is passed into NewFromStream.
+      // It is deleted if NewFromStream fails.
+      // If NewFromStream fails, we set |segment_stream_| to null so
+      // we aren't pointing to reclaimed memory.
+      segment_stream_ = nullptr;
+      return;
+    }
+
+    // SkCodec::NewFromStream will read enough of the image to get the image
+    // size.
+    SkImageInfo image_info = codec_->getInfo();
+    SetSize(image_info.width(), image_info.height());
+  }
 }
 
 int GIFImageDecoder::RepetitionCount() const {
+  if (!codec_)
+    return kCAnimationLoopOnce;
+
+  DCHECK(!Failed());
+
   // This value can arrive at any point in the image data stream.  Most GIFs
   // in the wild declare it near the beginning of the file, so it usually is
   // set by the time we've decoded the size, but (depending on the GIF and the
-  // packets sent back by the webserver) not always.  If the reader hasn't
-  // seen a loop count yet, it will return cLoopCountNotSeen, in which case we
-  // should default to looping once (the initial value for
-  // |m_repetitionCount|).
-  //
-  // There are some additional wrinkles here. First, ImageSource::clear()
-  // may destroy the reader, making the result from the reader _less_
-  // authoritative on future calls if the recreated reader hasn't seen the
-  // loop count.  We don't need to special-case this because in this case the
-  // new reader will once again return cLoopCountNotSeen, and we won't
-  // overwrite the cached correct value.
+  // packets sent back by the webserver) not always.
   //
-  // Second, a GIF might never set a loop count at all, in which case we
-  // should continue to treat it as a "loop once" animation.  We don't need
-  // special code here either, because in this case we'll never change
-  // |m_repetitionCount| from its default value.
-  //
-  // Third, we use the same GIFImageReader for counting frames and we might
-  // see the loop count and then encounter a decoding error which happens
-  // later in the stream. It is also possible that no frames are in the
-  // stream. In these cases we should just loop once.
-  if (IsAllDataReceived() && ParseCompleted() && reader_->imagesCount() == 1)
-    repetition_count_ = kCAnimationNone;
-  else if (Failed() || (reader_ && (!reader_->imagesCount())))
-    repetition_count_ = kCAnimationLoopOnce;
-  else if (reader_ && reader_->loopCount() != cLoopCountNotSeen)
-    repetition_count_ = reader_->loopCount();
-  return repetition_count_;
-}
+  // SkCodec will parse forward in the file if the repetition count has not been
+  // seen yet.
+  int repetition_count = codec_->getRepetitionCount();
 
-bool GIFImageDecoder::FrameIsCompleteAtIndex(size_t index) const {
-  return reader_ && (index < reader_->imagesCount()) &&
-         reader_->frameContext(index)->isComplete();
-}
-
-float GIFImageDecoder::FrameDurationAtIndex(size_t index) const {
-  return (reader_ && (index < reader_->imagesCount()) &&
-          reader_->frameContext(index)->isHeaderDefined())
-             ? reader_->frameContext(index)->delayTime()
-             : 0;
-}
+  switch (repetition_count) {
+    case 0: {
+      size_t frame_count = codec_->getFrameCount();
+      if (IsAllDataReceived() && frame_count == 1)
+        return kCAnimationNone;
 
-bool GIFImageDecoder::SetFailed() {
-  reader_.reset();
-  return ImageDecoder::SetFailed();
+      return kCAnimationLoopOnce;
+    }
+    case SkCodec::kRepetitionCountInfinite:
+      return kCAnimationLoopInfinite;
+    default:
+      return repetition_count;
+  }
 }
 
-bool GIFImageDecoder::HaveDecodedRow(size_t frame_index,
-                                     GIFRow::const_iterator row_begin,
-                                     size_t width,
-                                     size_t row_number,
-                                     unsigned repeat_count,
-                                     bool write_transparent_pixels) {
-  const GIFFrameContext* frame_context = reader_->frameContext(frame_index);
-  // The pixel data and coordinates supplied to us are relative to the frame's
-  // origin within the entire image size, i.e.
-  // (frameContext->xOffset, frameContext->yOffset). There is no guarantee
-  // that width == (size().width() - frameContext->xOffset), so
-  // we must ensure we don't run off the end of either the source data or the
-  // row's X-coordinates.
-  const int x_begin = frame_context->xOffset();
-  const int y_begin = frame_context->yOffset() + row_number;
-  const int x_end = std::min(static_cast<int>(frame_context->xOffset() + width),
-                             Size().Width());
-  const int y_end = std::min(
-      static_cast<int>(frame_context->yOffset() + row_number + repeat_count),
-      Size().Height());
-  if (!width || (x_begin < 0) || (y_begin < 0) || (x_end <= x_begin) ||
-      (y_end <= y_begin))
-    return true;
-
-  const GIFColorMap::Table& color_table =
-      frame_context->localColorMap().isDefined()
-          ? frame_context->localColorMap().getTable()
-          : reader_->globalColorMap().getTable();
-
-  if (color_table.IsEmpty())
-    return true;
-
-  GIFColorMap::Table::const_iterator color_table_iter = color_table.begin();
-
-  // Initialize the frame if necessary.
-  ImageFrame& buffer = frame_buffer_cache_[frame_index];
-  if (!InitFrameBuffer(frame_index))
+bool GIFImageDecoder::FrameIsCompleteAtIndex(size_t index) const {
+  if (!codec_)
     return false;
 
-  const size_t transparent_pixel = frame_context->transparentPixel();
-  GIFRow::const_iterator row_end = row_begin + (x_end - x_begin);
-  ImageFrame::PixelData* current_address = buffer.GetAddr(x_begin, y_begin);
-
-  // We may or may not need to write transparent pixels to the buffer.
-  // If we're compositing against a previous image, it's wrong, and if
-  // we're writing atop a cleared, fully transparent buffer, it's
-  // unnecessary; but if we're decoding an interlaced gif and
-  // displaying it "Haeberli"-style, we must write these for passes
-  // beyond the first, or the initial passes will "show through" the
-  // later ones.
-  //
-  // The loops below are almost identical. One writes a transparent pixel
-  // and one doesn't based on the value of |writeTransparentPixels|.
-  // The condition check is taken out of the loop to enhance performance.
-  // This optimization reduces decoding time by about 15% for a 3MB image.
-  if (write_transparent_pixels) {
-    for (; row_begin != row_end; ++row_begin, ++current_address) {
-      const size_t source_value = *row_begin;
-      if ((source_value != transparent_pixel) &&
-          (source_value < color_table.size())) {
-        *current_address = color_table_iter[source_value];
-      } else {
-        *current_address = 0;
-        current_buffer_saw_alpha_ = true;
-      }
-    }
-  } else {
-    for (; row_begin != row_end; ++row_begin, ++current_address) {
-      const size_t source_value = *row_begin;
-      if ((source_value != transparent_pixel) &&
-          (source_value < color_table.size()))
-        *current_address = color_table_iter[source_value];
-      else
-        current_buffer_saw_alpha_ = true;
-    }
-  }
-
-  // Tell the frame to copy the row data if need be.
-  if (repeat_count > 1)
-    buffer.CopyRowNTimes(x_begin, x_end, y_begin, y_end);
+  if (frame_infos_.size() <= index)
+    return false;
 
-  buffer.SetPixelsChanged(true);
-  return true;
+  return frame_infos_[index].fFullyReceived;
 }
 
-bool GIFImageDecoder::ParseCompleted() const {
-  return reader_ && reader_->parseCompleted();
+float GIFImageDecoder::FrameDurationAtIndex(size_t index) const {
+  if (index < frame_buffer_cache_.size())
+    return frame_buffer_cache_[index].Duration();
+  return 0;
 }
 
-bool GIFImageDecoder::FrameComplete(size_t frame_index) {
-  // Initialize the frame if necessary.  Some GIFs insert do-nothing frames,
-  // in which case we never reach haveDecodedRow() before getting here.
-  if (!InitFrameBuffer(frame_index))
-    return SetFailed();
-
-  if (!current_buffer_saw_alpha_)
-    CorrectAlphaWhenFrameBufferSawNoAlpha(frame_index);
-
-  frame_buffer_cache_[frame_index].SetStatus(ImageFrame::kFrameComplete);
-
-  return true;
-}
+bool GIFImageDecoder::SetFailed() {
+  DCHECK(codec_);
 
-void GIFImageDecoder::ClearFrameBuffer(size_t frame_index) {
-  if (reader_ && frame_buffer_cache_[frame_index].GetStatus() ==
-                     ImageFrame::kFramePartial) {
-    // Reset the state of the partial frame in the reader so that the frame
-    // can be decoded again when requested.
-    reader_->clearDecodeState(frame_index);
-  }
-  ImageDecoder::ClearFrameBuffer(frame_index);
+  segment_stream_ = nullptr;
+  codec_ = nullptr;
+  return ImageDecoder::SetFailed();
 }
 
 size_t GIFImageDecoder::DecodeFrameCount() {
-  Parse(kGIFFrameCountQuery);
-  // If decoding fails, |m_reader| will have been destroyed.  Instead of
-  // returning 0 in this case, return the existing number of frames.  This way
-  // if we get halfway through the image before decoding fails, we won't
-  // suddenly start reporting that the image has zero frames.
-  return Failed() ? frame_buffer_cache_.size() : reader_->imagesCount();
+  if (!codec_)
+    return 0;
+
+  if (!Failed() && !segment_stream_->IsCleared())
+    frame_infos_ = codec_->getFrameInfo();
+  return frame_infos_.size();
 }
 
 void GIFImageDecoder::InitializeNewFrame(size_t index) {
-  ImageFrame* buffer = &frame_buffer_cache_[index];
-  const GIFFrameContext* frame_context = reader_->frameContext(index);
-  buffer->SetOriginalFrameRect(
-      Intersection(frame_context->frameRect(), IntRect(IntPoint(), Size())));
-  buffer->SetDuration(frame_context->delayTime());
-  buffer->SetDisposalMethod(frame_context->getDisposalMethod());
-  buffer->SetRequiredPreviousFrameIndex(
-      FindRequiredPreviousFrame(index, false));
+  DCHECK(codec_);
+
+  ImageFrame& frame = frame_buffer_cache_[index];
+  // SkCodec does not inform us if only a portion of the image was updated
+  // in the current frame. Because of this, rather than correctly filling in
+  // the frame rect, we set the frame rect to be the image's full size.
+  // The original frame rect is not used, anyway.
+  IntSize full_image_size = Size();
+  frame.SetOriginalFrameRect(IntRect(IntPoint(), full_image_size));
+  frame.SetDuration(frame_infos_[index].fDuration);
+  frame.SetHasAlpha(!SkAlphaTypeIsOpaque(frame_infos_[index].fAlphaType));
+  size_t required_previous_frame_index;
+  if (frame_infos_[index].fRequiredFrame == SkCodec::kNone) {
+    required_previous_frame_index = WTF::kNotFound;
+  } else {
+    required_previous_frame_index =
+        static_cast<size_t>(frame_infos_[index].fRequiredFrame);
+  }
+  frame.SetRequiredPreviousFrameIndex(required_previous_frame_index);
+  // The disposal method is not required any more, but is left in place
+  // for the other image decoders that do not yet rely on SkCodec.
+  // For now, fill it with DisposeKeep.
+  frame.SetDisposalMethod(ImageFrame::kDisposeKeep);
 }
 
 void GIFImageDecoder::Decode(size_t index) {
-  Parse(kGIFFrameCountQuery);
+  if (!codec_)
+    return;
 
-  if (Failed())
+  DCHECK(!Failed());
+
+  if (segment_stream_->IsCleared())
     return;
 
   UpdateAggressivePurging(index);
+  SkImageInfo image_info = codec_->getInfo().makeColorType(kN32_SkColorType);
+
+  SkCodec::Options options;
+  options.fFrameIndex = index;
+  options.fHasPriorFrame = false;
+  options.fZeroInitialized = SkCodec::kNo_ZeroInitialized;
+
+  ImageFrame& frame = frame_buffer_cache_[index];
+  if (frame.GetStatus() == ImageFrame::kFrameEmpty) {
+    size_t required_previous_frame_index = frame.RequiredPreviousFrameIndex();
+    if (required_previous_frame_index == WTF::kNotFound) {
+      frame.AllocatePixelData(Size().Width(), Size().Height(),
+                              ColorSpaceForSkImages());
+    } else {
+      ImageFrame& required_previous_frame =
+          frame_buffer_cache_[required_previous_frame_index];
+
+      if (required_previous_frame.GetStatus() != ImageFrame::kFrameComplete)
+        Decode(required_previous_frame_index);
+
+      // We try to reuse |required_previous_frame| as starting state to avoid
+      // copying. If CanReusePreviousFrameBuffer returns false, we must copy
+      // the data since |required_previous_frame| is necessary to decode this
+      // or later frames. In that case copy the data instead.
+      if ((!CanReusePreviousFrameBuffer(index) ||
+           !frame.TakeBitmapDataIfWritable(&required_previous_frame)) &&
+          !frame.CopyBitmapData(required_previous_frame)) {
+        SetFailed();
+        return;
+      }
+      options.fHasPriorFrame = true;
+    }
+  }
 
-  Vector<size_t> frames_to_decode = FindFramesToDecode(index);
-  for (auto i = frames_to_decode.rbegin(); i != frames_to_decode.rend(); ++i) {
-    if (!reader_->decode(*i)) {
-      SetFailed();
-      return;
+  if (frame.GetStatus() == ImageFrame::kFrameAllocated) {
+    SkCodec::Result start_incremental_decode_result =
+        codec_->startIncrementalDecode(image_info, frame.Bitmap().getPixels(),
+                                       frame.Bitmap().rowBytes(), &options,
+                                       nullptr, nullptr);
+    switch (start_incremental_decode_result) {
+      case SkCodec::kSuccess:
+        break;
+      case SkCodec::kIncompleteInput:
+        return;
+      default:
+        SetFailed();
+        return;
     }
+    frame.SetStatus(ImageFrame::kFramePartial);
+  }
+  int rows_decoded = 0;
+  SkCodec::Result incremental_decode_result =
+      codec_->incrementalDecode(&rows_decoded);
+  switch (incremental_decode_result) {
+    case SkCodec::kSuccess:
+      frame.SetPixelsChanged(true);
+      frame.SetStatus(ImageFrame::kFrameComplete);
+      PostDecodeProcessing(index);
+      break;
+    case SkCodec::kIncompleteInput:
+      if (FrameIsCompleteAtIndex(index) || IsAllDataReceived()) {
+        SetFailed();
+        return;
+      }
+      {
+        IntRect remaining_rect = frame.OriginalFrameRect();
+        remaining_rect.SetY(rows_decoded);
+        remaining_rect.SetHeight(remaining_rect.Height() - rows_decoded);
+        frame.ZeroFillFrameRect(remaining_rect);
+        // ZeroFillFrameRect() resets the alpha to true.
+        // We want to preserve the alpha. So we need to set it back.
+        frame.SetHasAlpha(!SkAlphaTypeIsOpaque(frame_infos_[index].fAlphaType));
+      }
 
-    // If this returns false, we need more data to continue decoding.
-    if (!PostDecodeProcessing(*i))
+      frame.SetPixelsChanged(true);
       break;
+    default:
+      SetFailed();
+      return;
   }
-
-  // It is also a fatal error if all data is received and we have decoded all
-  // frames available but the file is truncated.
-  if (index >= frame_buffer_cache_.size() - 1 && IsAllDataReceived() &&
-      reader_ && !reader_->parseCompleted())
-    SetFailed();
 }
 
-void GIFImageDecoder::Parse(GIFParseQuery query) {
-  if (Failed())
-    return;
+bool GIFImageDecoder::CanReusePreviousFrameBuffer(size_t index) const {
+  DCHECK(index < frame_buffer_cache_.size());
 
-  if (!reader_) {
-    reader_ = WTF::MakeUnique<GIFImageReader>(this);
-    reader_->setData(data_);
-  }
+  // If the current frame and the next frame depend on the same frame, we cannot
+  // reuse the old frame. We must preserve it for the next frame.
+  //
+  // However, if the current and next frame depend on different frames then we
+  // know the current frame is the last one to use the frame it depends on. That
+  // means the current frame can reuse the previous frame buffer.
+  //
+  // If we do not have information about the next frame yet, we cannot assume it
+  // is safe to reuse the previous frame buffer.
 
-  if (!reader_->parse(query))
-    SetFailed();
-}
+  if (index + 1 >= frame_buffer_cache_.size())
+    return false;
 
-void GIFImageDecoder::OnInitFrameBuffer(size_t frame_index) {
-  current_buffer_saw_alpha_ = false;
-}
+  const ImageFrame& frame = frame_buffer_cache_[index];
+  size_t required_frame_index = frame.RequiredPreviousFrameIndex();
+
+  const ImageFrame& next_frame = frame_buffer_cache_[index + 1];
+  size_t next_required_frame_index = next_frame.RequiredPreviousFrameIndex();
 
-bool GIFImageDecoder::CanReusePreviousFrameBuffer(size_t frame_index) const {
-  DCHECK(frame_index < frame_buffer_cache_.size());
-  return frame_buffer_cache_[frame_index].GetDisposalMethod() !=
-         ImageFrame::kDisposeOverwritePrevious;
+  return required_frame_index != next_required_frame_index;
 }
 
 }  // namespace blink