Move gif image decoder to SkCodec

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

 /*
  * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #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 {
 
 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 we don't have a SkCodec yet, create one from the stream

[scroggo_chromium, 2017/04/24 20:25:07]

nit: This comment is probably not necessary.

[cblume, 2017/04/24 21:35:53]

Done.

+  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|).
+  // packets sent back by the webserver) not always.
   //
-  // 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.
-  //
-  // 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();
+
+  switch (repetition_count) {
+    case 0: {
+      size_t frame_count = codec_->getFrameCount();
+      if (IsAllDataReceived() && frame_count == 1)
+        return kCAnimationNone;
+
+      return kCAnimationLoopOnce;
+    }
+    case SkCodec::kRepetitionCountInfinite:
+      return kCAnimationLoopInfinite;
+    default:
+      return repetition_count;
+  }
 }
 
 bool GIFImageDecoder::FrameIsCompleteAtIndex(size_t index) const {
-  return reader_ && (index < reader_->imagesCount()) &&
-         reader_->frameContext(index)->isComplete();
+  if (!codec_)
+    return false;
+
+  if (frame_infos_.size() <= index)
+    return false;
+
+  return frame_infos_[index].fFullyReceived;
 }
 
 float GIFImageDecoder::FrameDurationAtIndex(size_t index) const {
-  return (reader_ && (index < reader_->imagesCount()) &&
-          reader_->frameContext(index)->isHeaderDefined())
-             ? reader_->frameContext(index)->delayTime()
-             : 0;
+  if (index < frame_buffer_cache_.size())
+    return frame_buffer_cache_[index].Duration();
+  return 0;
 }
 
 bool GIFImageDecoder::SetFailed() {
-  reader_.reset();
+  DCHECK(codec_);
+
+  segment_stream_ = nullptr;
+  codec_ = nullptr;
   return ImageDecoder::SetFailed();
 }
 
-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))
-    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;
+size_t GIFImageDecoder::DecodeFrameCount() {
+  if (!codec_)
+    return 0;
+
+  if (!Failed() && !segment_stream_->IsCleared())
+    frame_infos_ = codec_->getFrameInfo();
+  return frame_infos_.size();
+}
+
+void GIFImageDecoder::InitializeNewFrame(size_t index) {
+  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.

[scroggo_chromium, 2017/04/24 20:25:07]

Maybe add a comment that the original frame rect is not used anyway?

[cblume, 2017/04/24 21:35:53]

Done.

+  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) {
+  if (Failed())
+    return;
+
+  if (!codec_)

[scroggo_chromium, 2017/04/24 20:25:07]

This seems redundant. We cannot have a codec if we have Failed. How about:

void GIFImageDecoder::Decode(size_t index) {
  if (!codec)
    return;
  DCHECK(!Failed());
  ...

[cblume, 2017/04/24 21:35:53]

Done.

+    return;
+
+  if (segment_stream_->IsCleared())
+    return;
+
+  if (frame_buffer_cache_.size() <= index) {
+    // It is a fatal error if all data is received and we have decoded all

[scroggo_chromium, 2017/04/24 20:25:07]

It surprised me that this got moved up front. It seems like we could know there
is a failure at this point, but this will also change behavior, won't it?
Previously we would have decoded frames that |index| depends on, and now we
won't. But I'm not sure that will have an effect on what the user sees.

[cblume, 2017/04/24 21:35:53]

I think I see what you're saying.
Actually, this branch should never be entered anyway, right? We won't call
Decode(index) without first learning that there are more frames and increasing
the size of frame_buffer_cache_.
As is, I think this whole branch is useless.

The original branch checked if we're within known index bounds, all data is
received, but the parse still hasn't completed. That last bit is the part that
matters here.
If we have all the data but the parse is incomplete then the file is truncated.
That is the case we should be handling here.

That is also the case we handle down below, inside the switch for
incrementalDecode()'s result.

So I think I should just delete this branch.

[scroggo_chromium, 2017/04/25 15:31:40]

Agreed.
Maybe there should be a DCHECK(index < frame_buffer_cache_.size()) ? (Or I think
there is a LessThan variant of DCHECK.)
sgtm

[cblume, 2017/04/26 10:09:39]

Done.

+    // frames available but the file is truncated.
+    if (IsAllDataReceived())
+      SetFailed();
+
+    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;
       }
-    }
-  } 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);
-
-  buffer.SetPixelsChanged(true);
-  return true;
-}
-
-bool GIFImageDecoder::ParseCompleted() const {
-  return reader_ && reader_->parseCompleted();
-}
-
-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;
-}
-
-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);
-}
-
-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();
-}
-
-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));
-}
-
-void GIFImageDecoder::Decode(size_t index) {
-  Parse(kGIFFrameCountQuery);
-
-  if (Failed())
-    return;
-
-  UpdateAggressivePurging(index);
-
-  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)) {
+      options.fHasPriorFrame = true;
+    }
+  }
+
+  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);

[scroggo_chromium, 2017/04/24 20:25:07]

Should we check the return value? (At least to assert?)

[cblume, 2017/04/24 21:35:53]

I think we might not need that.
The returned bool only indicates whether the frame was fully decoded. It doesn't
indicate whether PostDecodeProcessing() succeeded or failed.
And we already know the frame was fully decoded.

+      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);
+        frame.SetHasAlpha(!SkAlphaTypeIsOpaque(frame_infos_[index].fAlphaType));

[scroggo_chromium, 2017/04/24 20:25:07]

Maybe add a comment that ZeroFillFrameRect changed has_alpha_ to true, but we
want to leave it whatever it was set by InitializeNewFrame?

[cblume, 2017/04/24 21:35:53]

Done.

+      }
+
+      frame.SetPixelsChanged(true);
+      break;
+    default:
       SetFailed();
       return;
-    }
-
-    // If this returns false, we need more data to continue decoding.
-    if (!PostDecodeProcessing(*i))
-      break;
-  }
-
-  // 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;
-
-  if (!reader_) {
-    reader_ = WTF::MakeUnique<GIFImageReader>(this);
-    reader_->setData(data_);
-  }
-
-  if (!reader_->parse(query))
-    SetFailed();
-}
-
-void GIFImageDecoder::OnInitFrameBuffer(size_t frame_index) {
-  current_buffer_saw_alpha_ = false;
-}
-
-bool GIFImageDecoder::CanReusePreviousFrameBuffer(size_t frame_index) const {
-  DCHECK(frame_index < frame_buffer_cache_.size());
-  return frame_buffer_cache_[frame_index].GetDisposalMethod() !=
-         ImageFrame::kDisposeOverwritePrevious;
+  }
+}
+
+bool GIFImageDecoder::CanReusePreviousFrameBuffer(size_t index) const {
+  DCHECK(index < frame_buffer_cache_.size());
+
+  // 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 (index + 1 >= frame_buffer_cache_.size())
+    return 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();
+
+  return required_frame_index != next_required_frame_index;
 }
 
 }  // namespace blink