Throttle rendering pipeline for invisible iframes

Source/core/frame/FrameView.h

 /*
    Copyright (C) 1997 Martin Jones (mjones@kde.org)
              (C) 1998 Waldo Bastian (bastian@kde.org)
              (C) 1998, 1999 Torben Weis (weis@kde.org)
              (C) 1999 Lars Knoll (knoll@kde.org)
              (C) 1999 Antti Koivisto (koivisto@kde.org)
    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
 
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
@@ skipping 208 matching lines @@
     void setIsPainting(bool val) { m_isPainting = val; }
     bool isPainting() const;
     void setLastPaintTime(double val) { m_lastPaintTime = val; }
     bool hasEverPainted() const { return m_lastPaintTime; }
     void setNodeToDraw(Node*);
     Node* nodeToDraw() { return m_nodeToDraw.get(); }
 
     Color documentBackgroundColor() const;
 
     // Run all needed lifecycle stages. After calling this method, all frames will be in the lifecycle state PaintInvalidationClean.
-    void updateAllLifecyclePhases();
+    // If lifecycle throttling is allowed, some frames may skip the lifecycle update (e.g., based on visibility) and will not end
+    // up being PaintInvalidationClean.
+    enum class LifecycleThrottlingMode { Disallow, Allow };
+    void updateAllLifecyclePhases(LifecycleThrottlingMode = LifecycleThrottlingMode::Disallow);
 
     // Computes the style, layout and compositing lifecycle stages if needed. After calling this method, all frames wil lbe in a lifecycle
     // state >= CompositingClean, and scrolling has been updated.
-    void updateLifecycleToCompositingCleanPlusScrolling();
+    void updateLifecycleToCompositingCleanPlusScrolling(LifecycleThrottlingMode = LifecycleThrottlingMode::Disallow);
 
     bool invalidateViewportConstrainedObjects();
 
     void incrementVisuallyNonEmptyCharacterCount(unsigned);
     void incrementVisuallyNonEmptyPixelCount(const IntSize&);
     bool isVisuallyNonEmpty() const { return m_isVisuallyNonEmpty; }
     void setIsVisuallyNonEmpty() { m_isVisuallyNonEmpty = true; }
     void enableAutoSizeMode(const IntSize& minSize, const IntSize& maxSize);
     void disableAutoSizeMode();
 
@@ skipping 308 matching lines @@
     // Returns true if the default scrolling direction is vertical. i.e. writing mode
     // is horiziontal. In a vertical document, a spacebar scrolls down.
     bool isVerticalDocument() const;
 
     // Returns true if the document's writing mode is right-to-left or bottom-to-top.
     bool isFlippedDocument() const;
 
     void setFrameTimingRequestsDirty(bool isDirty) { m_frameTimingRequestsDirty = isDirty; }
     bool frameTimingRequestsDirty() { return m_frameTimingRequestsDirty; }
 
+    // Returns true if this frame should skip rendering pipeline processing during the
+    // current BeginMainFrame.
+    bool shouldThrottleRenderingPipeline() const;
+
+    // Returns true if this frame should skip style computation, layout and
+    // compositing updates for the current BeginMainFrame.
+    bool shouldThrottleStyleLayoutAndCompositingUpdates() const;
+
+    // Updates the throttling status of all frames in the hierarchy and
+    // schedules new animations or lifecycle updates as necessary. Must be
+    // called after the layer update phase of the current BeginMainFrame.
+    void updateThrottling();
+
 protected:
     // Scroll the content via the compositor.
     bool scrollContentsFastPath(const IntSize& scrollDelta);
 
     // Scroll the content by invalidating everything.
     void scrollContentsSlowPath(const IntRect& updateRect);
 
     // These functions are used to create/destroy scrollbars.
     void setHasHorizontalScrollbar(bool);
     void setHasVerticalScrollbar(bool);
@@ skipping 33 matching lines @@
     explicit FrameView(LocalFrame*);
 
     void setScrollOffset(const IntPoint&, ScrollType) override;
     void setScrollOffset(const DoublePoint&, ScrollType) override;
 
     enum LifeCycleUpdateOption {
         AllPhases,
         OnlyUpToCompositingCleanPlusScrolling,
     };
 
-    void updateLifecyclePhasesInternal(LifeCycleUpdateOption);
+    void updateLifecyclePhasesInternal(LifeCycleUpdateOption, LifecycleThrottlingMode);
     void invalidateTreeIfNeededRecursive();
     void scrollContentsIfNeededRecursive();
     void updateStyleAndLayoutIfNeededRecursive();
     void paintForSlimmingPaintV2();
     void compositeForSlimmingPaintV2();
 
     void reset();
     void init();
 
     void clearLayoutSubtreeRootsAndMarkContainingBlocks();
@@ skipping 84 matching lines @@
     // LayoutObject for the viewport-defining element (see Document::viewportDefiningElement).
     LayoutObject* viewportLayoutObject();
 
     void collectAnnotatedRegions(LayoutObject&, Vector<AnnotatedRegionValue>&);
 
     typedef WTF::HashMap <const GraphicsLayer*, Vector<std::pair<int64_t, WebRect>>> GraphicsLayerFrameTimingRequests;
     void updateFrameTimingRequestsIfNeeded();
     void collectFrameTimingRequests(GraphicsLayerFrameTimingRequests&);
     void collectFrameTimingRequestsRecursive(GraphicsLayerFrameTimingRequests&);
 
+    void computeViewportVisibility();
+    void setLifecycleThrottlingModeRecursive(LifecycleThrottlingMode);
+    void updateThrottlingRecursive(bool hasCrossedSecurityOrigin);
+
     LayoutSize m_size;
 
     typedef HashSet<RefPtr<LayoutEmbeddedObject>> EmbeddedObjectSet;
     EmbeddedObjectSet m_partUpdateSet;
 
     // FIXME: These are just "children" of the FrameView and should be RefPtrWillBeMember<Widget> instead.
     HashSet<RefPtr<LayoutPart>> m_parts;
 
     // The RefPtr cycle between LocalFrame and FrameView is broken
     // when a LocalFrame is detached by LocalFrame::detach().
@@ skipping 102 matching lines @@
     OwnPtr<LayoutAnalyzer> m_analyzer;
 
     // Mark if something has changed in the mapping from Frame to GraphicsLayer
     // and the Frame Timing regions should be recalculated.
     bool m_frameTimingRequestsDirty;
 
     // Exists only on root frame.
     // TODO(bokan): crbug.com/484188. We should specialize FrameView for the
     // main frame.
     OwnPtrWillBeMember<ScrollableArea> m_viewportScrollableArea;
+
+    LifecycleThrottlingMode m_lifecycleThrottlingMode;
+    // This frame's bounds in the root frame's content coordinates, clipped
+    // recursively through every ancestor view.
+    IntRect m_clippedBounds;
+
+    enum class ViewportVisibility { Hidden, Visible, Unknown };
+    ViewportVisibility m_viewportVisibility;
+
+    // The following members control rendering pipeline throttling for this
+    // frame. They are only updated at the end of the pipeline (after painting)
+    // to avoid running further pipeline stages for a frame without having gone
+    // through the previous ones.
+    ViewportVisibility m_viewportVisibilityForThrottling;
+    bool m_isCrossOriginForThrottling;
 };
 
 inline void FrameView::incrementVisuallyNonEmptyCharacterCount(unsigned count)
 {
     if (m_isVisuallyNonEmpty)
         return;
     m_visuallyNonEmptyCharacterCount += count;
     // Use a threshold value to prevent very small amounts of visible content from triggering didFirstVisuallyNonEmptyLayout.
     // The first few hundred characters rarely contain the interesting content of the page.
     static const unsigned visualCharacterThreshold = 200;
@@ skipping 10 matching lines @@
     static const unsigned visualPixelThreshold = 32 * 32;
     if (m_visuallyNonEmptyPixelCount > visualPixelThreshold)
         setIsVisuallyNonEmpty();
 }
 
 DEFINE_TYPE_CASTS(FrameView, Widget, widget, widget->isFrameView(), widget.isFrameView());
 
 } // namespace blink
 
 #endif // FrameView_h