Checking if frame is complete and access duration doesn't need a decode

Source/core/platform/image-decoders/gif/GIFImageDecoder.h

 /*
  * 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 31 matching lines @@
         enum GIFQuery { GIFFullQuery, GIFSizeQuery, GIFFrameCountQuery };
 
         // ImageDecoder
         virtual String filenameExtension() const { return "gif"; }
         virtual void setData(SharedBuffer* data, bool allDataReceived);
         virtual bool isSizeAvailable();
         virtual bool setSize(unsigned width, unsigned height);
         virtual size_t frameCount();
         virtual int repetitionCount() const;
         virtual ImageFrame* frameBufferAtIndex(size_t index);
+        virtual bool frameIsCompleteAtIndex(size_t) const;
+        virtual float frameDurationAtIndex(size_t) const;
         // CAUTION: setFailed() deletes |m_reader|.  Be careful to avoid
         // accessing deleted memory, especially when calling this from inside
         // GIFImageReader!
         virtual bool setFailed();
         virtual void clearFrameBufferCache(size_t clearBeforeFrame);
 
         // Callbacks from the GIF reader.
         bool haveDecodedRow(unsigned frameIndex, const Vector<unsigned char>& rowBuffer, size_t width, size_t rowNumber, unsigned repeatCount, bool writeTransparentPixels);
         bool frameComplete(unsigned frameIndex, unsigned frameDuration, ImageFrame::FrameDisposalMethod disposalMethod);
         void gifComplete();
 
     private:
         // If the query is GIFFullQuery, decodes the image up to (but not
         // including) |haltAtFrame|.  Otherwise, decodes as much as is needed to
         // answer the query, ignoring bitmap data.  If decoding fails but there
         // is no more data coming, sets the "decode failure" flag.
         void decode(unsigned haltAtFrame, GIFQuery);
 
         // Called to initialize the frame buffer with the given index, based on
         // the previous frame's disposal method. Returns true on success. On
         // failure, this will mark the image as failed.
         bool initFrameBuffer(unsigned frameIndex);
 
+        // Return true only if the file is known to be truncated.
+        bool truncated() const;
+
         bool m_currentBufferSawAlpha;
         mutable int m_repetitionCount;
         OwnPtr<GIFImageReader> m_reader;
     };
 
 } // namespace WebCore
 
 #endif