High CPU and increased memory usage fix for high-res (GIF, WEBP...) animations.

third_party/WebKit/Source/platform/graphics/BitmapImage.h

 /*
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2004, 2005, 2006 Apple Computer, Inc.  All rights reserved.
  * Copyright (C) 2008-2009 Torch Mobile, Inc.
  *
  * 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.
@@ skipping 26 matching lines @@
 #include "platform/graphics/ImageSource.h"
 #include "platform/image-decoders/ImageAnimation.h"
 #include "wtf/Forward.h"
 #include "wtf/OwnPtr.h"
 
 namespace blink {
 
 template <typename T> class Timer;
 
 class PLATFORM_EXPORT BitmapImage final : public Image {
+    friend class BitmapImageTest;
+    friend class CrossfadeGeneratedImage;
     friend class GeneratedImage;
-    friend class CrossfadeGeneratedImage;
     friend class GradientGeneratedImage;
     friend class GraphicsContext;
 public:
     static PassRefPtr<BitmapImage> create(ImageObserver* observer = 0)
     {
         return adoptRef(new BitmapImage(observer));
     }
 
     ~BitmapImage() override;
 
     bool isBitmapImage() const override { return true; }
 
     bool currentFrameHasSingleSecurityOrigin() const override;
 
     IntSize size() const override;
     IntSize sizeRespectingOrientation() const;
     bool getHotSpot(IntPoint&) const override;
     String filenameExtension() const override;
     bool dataChanged(bool allDataReceived) override;
 
     bool isAllDataReceived() const { return m_allDataReceived; }
     bool hasColorProfile() const;
 
-    // It may look unusual that there's no start animation call as public API.
-    // This because we start and stop animating lazily. Animation starts when
-    // the image is rendered, and automatically pauses once all observers no
-    // longer want to render the image.
-    void stopAnimation() override;
     void resetAnimation() override;
     bool maybeAnimated() override;
 
     void setAnimationPolicy(ImageAnimationPolicy policy) override { m_animationPolicy = policy; }
     ImageAnimationPolicy animationPolicy() override { return m_animationPolicy; }
     void advanceTime(double deltaTimeInSeconds) override;
 
     PassRefPtr<SkImage> imageForCurrentFrame() override;
     PassRefPtr<Image> imageForDefaultFrame() override;
 
     bool currentFrameKnownToBeOpaque(MetadataMode = UseCurrentMetadata) override;
     bool currentFrameIsComplete() override;
     bool currentFrameIsLazyDecoded() override;
 
     ImageOrientation currentFrameOrientation();
 
     // Construct a BitmapImage with the given orientation.
     static PassRefPtr<BitmapImage> createWithOrientationForTesting(const SkBitmap&, ImageOrientation);
     // Advance the image animation by one frame.
     void advanceAnimationForTesting() override { internalAdvanceAnimation(false); }
 
 private:
-    friend class BitmapImageTest;
-
-    void updateSize() const;
-
-private:
     enum RepetitionCountStatus {
       Unknown,    // We haven't checked the source's repetition count.
       Uncertain,  // We have a repetition count, but it might be wrong (some GIFs have a count after the image data, and will report "loop once" until all data has been decoded).
       Certain     // The repetition count is known to be correct.
     };
 
     BitmapImage(const SkBitmap &, ImageObserver* = 0);
     BitmapImage(ImageObserver* = 0);
 
     void draw(SkCanvas*, const SkPaint&, const FloatRect& dstRect, const FloatRect& srcRect, RespectImageOrientationEnum, ImageClampingMode) override;
 
     size_t currentFrame() const { return m_currentFrame; }
     size_t frameCount();
 
     PassRefPtr<SkImage> frameAtIndex(size_t);
 
     bool frameIsCompleteAtIndex(size_t);
     float frameDurationAtIndex(size_t);
     bool frameHasAlphaAtIndex(size_t);
     ImageOrientation frameOrientationAtIndex(size_t);
 
-    // Decodes and caches a frame. Never accessed except internally.
-    void cacheFrame(size_t index);
-
-    // Called before accessing m_frames[index]. Returns false on index out of bounds.
-    bool ensureFrameIsCached(size_t index);
+    PassRefPtr<SkImage> decodeAndCacheFrame(size_t index);
+    void updateSize() const;
 
     // Returns the total number of bytes allocated for all framebuffers, i.e.
     // the sum of m_source.frameBytesAtIndex(...) for all frames.
     size_t totalFrameBytes();
 
-    // Called to invalidate cached data. When |destroyAll| is true, we wipe out
-    // the entire frame buffer cache and tell the image source to destroy
-    // everything; this is used when e.g. we want to free some room in the image
-    // cache. If |destroyAll| is false, we delete frames except the current
-    // frame; this is used while animating large images to keep memory footprint
-    // low; the decoder should preserve the current frame and may preserve some
-    // other frames to avoid redecoding the whole image on every frame.
-    void destroyDecodedData(bool destroyAll) override;
-
-    // If the image is large enough, calls destroyDecodedData().
-    void destroyDecodedDataIfNecessary();
+    // Called to wipe out the entire frame buffer cache and tell the image
+    // source to destroy everything; this is used when e.g. we want to free
+    // some room in the image cache.
+    void destroyDecodedData() override;
 
     // Notifies observers that the memory footprint has changed.
     void notifyMemoryChanged();
 
     // Whether or not size is available yet.
     bool isSizeAvailable();
 
     // Animation.
+    // We start and stop animating lazily.  Animation starts when the image is
+    // rendered, and automatically stops once no observer wants to render the
+    // image.
     int repetitionCount(bool imageKnownToBeComplete);  // |imageKnownToBeComplete| should be set if the caller knows the entire image has been decoded.
     bool shouldAnimate();
     void startAnimation(CatchUpAnimation = CatchUp) override;
+    void stopAnimation();
     void advanceAnimation(Timer<BitmapImage>*);
 
     // Function that does the real work of advancing the animation.  When
     // skippingFrames is true, we're in the middle of a loop trying to skip over
     // a bunch of animation frames, so we should not do things like decode each
     // one or notify our observers.
     // Returns whether the animation was advanced.
     bool internalAdvanceAnimation(bool skippingFrames);
 
     ImageSource m_source;
     mutable IntSize m_size; // The size to use for the overall image (will just be the size of the first image).
     mutable IntSize m_sizeRespectingOrientation;
 
     size_t m_currentFrame; // The index of the current frame of animation.
     Vector<FrameData, 1> m_frames; // An array of the cached frames of the animation. We have to ref frames to pin them in the cache.
 
+    RefPtr<SkImage> m_cachedFrame; // A cached copy of the most recently-accessed frame.
+    size_t m_cachedFrameIndex; // Index of the frame that is cached.
+
     OwnPtr<Timer<BitmapImage>> m_frameTimer;
     int m_repetitionCount; // How many total animation loops we should do.  This will be cAnimationNone if this image type is incapable of animation.
     RepetitionCountStatus m_repetitionCountStatus;
     int m_repetitionsComplete;  // How many repetitions we've finished.
     double m_desiredFrameStartTime;  // The system time at which we hope to see the next call to startAnimation().
 
     size_t m_frameCount;
 
     ImageAnimationPolicy m_animationPolicy; // Whether or not we can play animation.
 
     bool m_animationFinished : 1; // Whether or not we've completed the entire animation.
 
     bool m_allDataReceived : 1; // Whether or not we've received all our data.
     mutable bool m_haveSize : 1; // Whether or not our |m_size| member variable has the final overall image size yet.
     bool m_sizeAvailable : 1; // Whether or not we can obtain the size of the first image frame yet from ImageIO.
     mutable bool m_haveFrameCount : 1;
 };
 
 DEFINE_IMAGE_TYPE_CASTS(BitmapImage);
 
 } // namespace blink
 
 #endif