Fix ImageDecoder::frameIsCompleteAtIndex - fully received instead of decoded.

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
@@ skipping 65 matching lines @@
     // stream. In these cases we should just loop once.
     if (isAllDataReceived() && parseCompleted() && m_reader->imagesCount() == 1)
         m_repetitionCount = cAnimationNone;
     else if (failed() || (m_reader && (!m_reader->imagesCount())))
         m_repetitionCount = cAnimationLoopOnce;
     else if (m_reader && m_reader->loopCount() != cLoopCountNotSeen)
         m_repetitionCount = m_reader->loopCount();
     return m_repetitionCount;
 }
 
-bool GIFImageDecoder::frameIsCompleteAtIndex(size_t index) const
+bool GIFImageDecoder::frameIsFullyReceivedAtIndex(size_t index) const
 {
     return m_reader && (index < m_reader->imagesCount()) && m_reader->frameContext(index)->isComplete();

[Peter Kasting, 2016/05/10 00:00:13]

Hmm.  This will always return false if decoding fails (i.e. if setFailed()
returns true).  Maybe it should always return true in that case instead?

[aleksandar.stojiljkovic, 2016/05/10 21:59:31]

What would be the usage of returning "frame is fully received" in case of
failure? 

[Peter Kasting, 2016/05/11 00:33:02]

We know we're not going to do any further updating/decoding, so anyone wanting
to know "is the image finalizable" should probably get back "yes".

[aleksandar.stojiljkovic, 2016/05/11 11:05:15]

The usage of this is in [1] - GraphicsContext::computeFilterQuality.
If image is not fully received, then lower quality interpolation is used. So for
case of failure we don't use high quality sampling. I think it is better to
leave it as it was.

[1]
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/WebKit...

[scroggo_chromium, 2016/05/11 15:17:34]

But it also will be used in crrev.com/1925533003 to state that we should use the
same genID so we'll use the same image from the cache, right?

[Peter Kasting, 2016/05/11 18:29:34]

The only reason we ever use low-quality filtering is so we don't spend too much
time filtering an image which is going to be erased momentarily and redrawn in a
different state.  Once failure occurs the image is finalized, we don't redraw
it, and thus we should use high-quality filtering, even on failed images.

[aleksandar.stojiljkovic, 2016/05/16 13:09:49]

Done.
Clear now; failed() added to "fully received" computation.

 }
 
 float GIFImageDecoder::frameDurationAtIndex(size_t index) const
 {
     return (m_reader && (index < m_reader->imagesCount()) &&
         m_reader->frameContext(index)->isHeaderDefined()) ?
         m_reader->frameContext(index)->delayTime() : 0;
 }
 
 bool GIFImageDecoder::setFailed()
@@ skipping 269 matching lines @@
 
     // Update our status to be partially complete.
     buffer->setStatus(ImageFrame::FramePartial);
 
     // Reset the alpha pixel tracker for this frame.
     m_currentBufferSawAlpha = false;
     return true;
 }
 
 } // namespace blink