Fix updating of tiled backing opaquenss when the page background color changes
[WebKit-https.git] / Source / WebCore / rendering / RenderLayerCompositor.h
1 /*
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6  * are met:
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10  *    notice, this list of conditions and the following disclaimer in the
11  *    documentation and/or other materials provided with the distribution.
12  *
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25
26 #ifndef RenderLayerCompositor_h
27 #define RenderLayerCompositor_h
28
29 #include "ChromeClient.h"
30 #include "GraphicsLayerClient.h"
31 #include "GraphicsLayerUpdater.h"
32 #include "RenderLayer.h"
33 #include <wtf/HashMap.h>
34
35 namespace WebCore {
36
37 class FixedPositionViewportConstraints;
38 class GraphicsLayer;
39 class GraphicsLayerUpdater;
40 class RenderEmbeddedObject;
41 class RenderNamedFlowFragment;
42 class RenderVideo;
43 class RenderWidget;
44 class ScrollingCoordinator;
45 class StickyPositionViewportConstraints;
46 class TiledBacking;
47
48 typedef unsigned LayerTreeFlags;
49
50 enum CompositingUpdateType {
51     CompositingUpdateAfterStyleChange,
52     CompositingUpdateAfterLayout,
53     CompositingUpdateOnHitTest,
54     CompositingUpdateOnScroll,
55     CompositingUpdateOnCompositedScroll
56 };
57
58 enum {
59     CompositingReasonNone                                   = 0,
60     CompositingReason3DTransform                            = 1 << 0,
61     CompositingReasonVideo                                  = 1 << 1,
62     CompositingReasonCanvas                                 = 1 << 2,
63     CompositingReasonPlugin                                 = 1 << 3,
64     CompositingReasonIFrame                                 = 1 << 4,
65     CompositingReasonBackfaceVisibilityHidden               = 1 << 5,
66     CompositingReasonClipsCompositingDescendants            = 1 << 6,
67     CompositingReasonAnimation                              = 1 << 7,
68     CompositingReasonFilters                                = 1 << 8,
69     CompositingReasonPositionFixed                          = 1 << 9,
70     CompositingReasonPositionSticky                         = 1 << 10,
71     CompositingReasonOverflowScrollingTouch                 = 1 << 11,
72     CompositingReasonStacking                               = 1 << 12,
73     CompositingReasonOverlap                                = 1 << 13,
74     CompositingReasonNegativeZIndexChildren                 = 1 << 14,
75     CompositingReasonTransformWithCompositedDescendants     = 1 << 15,
76     CompositingReasonOpacityWithCompositedDescendants       = 1 << 16,
77     CompositingReasonMaskWithCompositedDescendants          = 1 << 17,
78     CompositingReasonReflectionWithCompositedDescendants    = 1 << 18,
79     CompositingReasonFilterWithCompositedDescendants        = 1 << 19,
80     CompositingReasonBlendingWithCompositedDescendants      = 1 << 20,
81     CompositingReasonPerspective                            = 1 << 21,
82     CompositingReasonPreserve3D                             = 1 << 22,
83     CompositingReasonRoot                                   = 1 << 23,
84     CompositingReasonIsolatesCompositedBlendingDescendants  = 1 << 24,
85 };
86 typedef unsigned CompositingReasons;
87
88 // RenderLayerCompositor manages the hierarchy of
89 // composited RenderLayers. It determines which RenderLayers
90 // become compositing, and creates and maintains a hierarchy of
91 // GraphicsLayers based on the RenderLayer painting order.
92 // 
93 // There is one RenderLayerCompositor per RenderView.
94
95 class RenderLayerCompositor final : public GraphicsLayerClient, public GraphicsLayerUpdaterClient {
96     WTF_MAKE_FAST_ALLOCATED;
97 public:
98     explicit RenderLayerCompositor(RenderView&);
99     virtual ~RenderLayerCompositor();
100
101     // Return true if this RenderView is in "compositing mode" (i.e. has one or more
102     // composited RenderLayers)
103     bool inCompositingMode() const { return m_compositing; }
104     // This will make a compositing layer at the root automatically, and hook up to
105     // the native view/window system.
106     void enableCompositingMode(bool enable = true);
107
108     bool inForcedCompositingMode() const { return m_forceCompositingMode; }
109
110     // Returns true if the accelerated compositing is enabled
111     bool hasAcceleratedCompositing() const { return m_hasAcceleratedCompositing; }
112
113     bool canRender3DTransforms() const;
114
115     // Copy the accelerated compositing related flags from Settings
116     void cacheAcceleratedCompositingFlags();
117
118     // Called when the layer hierarchy needs to be updated (compositing layers have been
119     // created, destroyed or re-parented).
120     void setCompositingLayersNeedRebuild(bool needRebuild = true);
121     bool compositingLayersNeedRebuild() const { return m_compositingLayersNeedRebuild; }
122     
123     void willRecalcStyle();
124     void didRecalcStyleWithNoPendingLayout();
125
126     // GraphicsLayers buffer state, which gets pushed to the underlying platform layers
127     // at specific times.
128     void scheduleLayerFlush(bool canThrottle);
129     void flushPendingLayerChanges(bool isFlushRoot = true);
130     
131     // flushPendingLayerChanges() flushes the entire GraphicsLayer tree, which can cross frame boundaries.
132     // This call returns the rootmost compositor that is being flushed (including self).
133     RenderLayerCompositor* enclosingCompositorFlushingLayers() const;
134
135     // Called when the GraphicsLayer for the given RenderLayer has flushed changes inside of flushPendingLayerChanges().
136     void didFlushChangesForLayer(RenderLayer&, const GraphicsLayer*);
137
138     // Called when something outside WebKit affects the visible rect (e.g. delegated scrolling). Might schedule a layer flush.
139     void didChangeVisibleRect();
140     
141     // Rebuild the tree of compositing layers
142     void updateCompositingLayers(CompositingUpdateType, RenderLayer* updateRoot = nullptr);
143     // This is only used when state changes and we do not exepect a style update or layout to happen soon (e.g. when
144     // we discover that an iframe is overlapped during painting).
145     void scheduleCompositingLayerUpdate();
146     // This is used to cancel any pending update timers when the document goes into page cache.
147     void cancelCompositingLayerUpdate();
148
149     // Update the compositing state of the given layer. Returns true if that state changed.
150     enum CompositingChangeRepaint { CompositingChangeRepaintNow, CompositingChangeWillRepaintLater };
151     bool updateLayerCompositingState(RenderLayer&, CompositingChangeRepaint = CompositingChangeRepaintNow);
152
153     // Update the geometry for compositing children of compositingAncestor.
154     void updateCompositingDescendantGeometry(RenderLayer& compositingAncestor, RenderLayer&, bool compositedChildrenOnly);
155     
156     // Whether layer's backing needs a graphics layer to do clipping by an ancestor (non-stacking-context parent with overflow).
157     bool clippedByAncestor(RenderLayer&) const;
158     // Whether layer's backing needs a graphics layer to clip z-order children of the given layer.
159     bool clipsCompositingDescendants(const RenderLayer&) const;
160
161     // Whether the given layer needs an extra 'contents' layer.
162     bool needsContentsCompositingLayer(const RenderLayer&) const;
163
164     bool supportsFixedRootBackgroundCompositing() const;
165     bool needsFixedRootBackgroundLayer(const RenderLayer&) const;
166     GraphicsLayer* fixedRootBackgroundLayer() const;
167     
168     // Called after the view transparency, or the document or base background color change.
169     void rootBackgroundTransparencyChanged();
170     
171     // Repaint the appropriate layers when the given RenderLayer starts or stops being composited.
172     void repaintOnCompositingChange(RenderLayer&);
173     
174     void repaintInCompositedAncestor(RenderLayer&, const LayoutRect&);
175     
176     // Notify us that a layer has been added or removed
177     void layerWasAdded(RenderLayer& parent, RenderLayer& child);
178     void layerWillBeRemoved(RenderLayer& parent, RenderLayer& child);
179
180     void layerStyleChanged(StyleDifference, RenderLayer&, const RenderStyle* oldStyle);
181
182     static bool canCompositeClipPath(const RenderLayer&);
183
184     // Get the nearest ancestor layer that has overflow or clip, but is not a stacking context
185     RenderLayer* enclosingNonStackingClippingLayer(const RenderLayer&) const;
186
187     // Repaint all composited layers.
188     void repaintCompositedLayers();
189
190     // Returns true if the given layer needs it own backing store.
191     bool requiresOwnBackingStore(const RenderLayer&, const RenderLayer* compositingAncestorLayer, const LayoutRect& layerCompositedBoundsInAncestor, const LayoutRect& ancestorCompositedBounds) const;
192
193     WEBCORE_EXPORT RenderLayer& rootRenderLayer() const;
194     GraphicsLayer* rootGraphicsLayer() const;
195     WEBCORE_EXPORT GraphicsLayer* scrollLayer() const;
196     GraphicsLayer* clipLayer() const;
197     GraphicsLayer* rootContentLayer() const;
198
199 #if ENABLE(RUBBER_BANDING)
200     GraphicsLayer* headerLayer() const;
201     GraphicsLayer* footerLayer() const;
202 #endif
203
204     enum RootLayerAttachment {
205         RootLayerUnattached,
206         RootLayerAttachedViaChromeClient,
207         RootLayerAttachedViaEnclosingFrame
208     };
209
210     RootLayerAttachment rootLayerAttachment() const { return m_rootLayerAttachment; }
211     void updateRootLayerAttachment();
212     void updateRootLayerPosition();
213     
214     void setIsInWindow(bool);
215
216     void clearBackingForAllLayers();
217     
218     void layerBecameComposited(const RenderLayer&) { ++m_compositedLayerCount; }
219     void layerBecameNonComposited(const RenderLayer&);
220     
221 #if ENABLE(VIDEO)
222     // Use by RenderVideo to ask if it should try to use accelerated compositing.
223     bool canAccelerateVideoRendering(RenderVideo&) const;
224 #endif
225
226     // Walk the tree looking for layers with 3d transforms. Useful in case you need
227     // to know if there is non-affine content, e.g. for drawing into an image.
228     bool has3DContent() const;
229     
230     // Most platforms connect compositing layer trees between iframes and their parent document.
231     // Some (currently just Mac) allow iframes to do their own compositing.
232     static bool allowsIndependentlyCompositedFrames(const FrameView*);
233     bool shouldPropagateCompositingToEnclosingFrame() const;
234
235     static RenderLayerCompositor* frameContentsCompositor(RenderWidget*);
236     // Return true if the layers changed.
237     static bool parentFrameContentLayers(RenderWidget*);
238
239     // Update the geometry of the layers used for clipping and scrolling in frames.
240     void frameViewDidChangeLocation(const IntPoint& contentsOffset);
241     void frameViewDidChangeSize();
242     void frameViewDidScroll();
243     void frameViewDidAddOrRemoveScrollbars();
244     void frameViewDidLayout();
245     void rootFixedBackgroundsChanged();
246
247     void scrollingLayerDidChange(RenderLayer&);
248     void fixedRootBackgroundLayerChanged();
249
250     String layerTreeAsText(LayerTreeFlags);
251
252     virtual float deviceScaleFactor() const override;
253     virtual float contentsScaleMultiplierForNewTiles(const GraphicsLayer*) const override;
254     virtual float pageScaleFactor() const override;
255     virtual float zoomedOutPageScaleFactor() const override;
256
257     virtual void didCommitChangesForLayer(const GraphicsLayer*) const override;
258     virtual void notifyFlushBeforeDisplayRefresh(const GraphicsLayer*) override;
259
260     void layerTiledBackingUsageChanged(const GraphicsLayer*, bool /*usingTiledBacking*/);
261     
262     bool acceleratedDrawingEnabled() const { return m_acceleratedDrawingEnabled; }
263
264     void deviceOrPageScaleFactorChanged();
265
266     void windowScreenDidChange(PlatformDisplayID);
267
268     GraphicsLayer* layerForHorizontalScrollbar() const { return m_layerForHorizontalScrollbar.get(); }
269     GraphicsLayer* layerForVerticalScrollbar() const { return m_layerForVerticalScrollbar.get(); }
270     GraphicsLayer* layerForScrollCorner() const { return m_layerForScrollCorner.get(); }
271 #if ENABLE(RUBBER_BANDING)
272     GraphicsLayer* layerForOverhangAreas() const { return m_layerForOverhangAreas.get(); }
273     GraphicsLayer* layerForContentShadow() const { return m_contentShadowLayer.get(); }
274
275     GraphicsLayer* updateLayerForTopOverhangArea(bool wantsLayer);
276     GraphicsLayer* updateLayerForBottomOverhangArea(bool wantsLayer);
277     GraphicsLayer* updateLayerForHeader(bool wantsLayer);
278     GraphicsLayer* updateLayerForFooter(bool wantsLayer);
279 #endif
280
281     ScrollableArea* scrollableAreaForScrollLayerID(ScrollingNodeID) const;
282
283     void updateScrollCoordinatedStatus(RenderLayer&);
284     void removeFromScrollCoordinatedLayers(RenderLayer&);
285
286     void willRemoveScrollingLayerWithBacking(RenderLayer&, RenderLayerBacking&);
287     void didAddScrollingLayer(RenderLayer&);
288
289 #if PLATFORM(IOS)
290     void registerAllViewportConstrainedLayers();
291     void unregisterAllViewportConstrainedLayers();
292
293     void registerAllScrollingLayers();
294     void unregisterAllScrollingLayers();
295 #endif
296
297     void resetTrackedRepaintRects();
298     void setTracksRepaints(bool);
299
300     void setShouldReevaluateCompositingAfterLayout() { m_reevaluateCompositingAfterLayout = true; }
301
302     bool viewHasTransparentBackground(Color* backgroundColor = nullptr) const;
303
304     bool hasNonMainLayersWithTiledBacking() const { return m_layersWithTiledBackingCount; }
305
306     CompositingReasons reasonsForCompositing(const RenderLayer&) const;
307
308     void setLayerFlushThrottlingEnabled(bool);
309     void disableLayerFlushThrottlingTemporarilyForInteraction();
310     
311     void didPaintBacking(RenderLayerBacking*);
312
313     void setRootExtendedBackgroundColor(const Color&);
314     Color rootExtendedBackgroundColor() const { return m_rootExtendedBackgroundColor; }
315
316     // For testing.
317     WEBCORE_EXPORT void startTrackingLayerFlushes();
318     WEBCORE_EXPORT unsigned layerFlushCount() const;
319
320     WEBCORE_EXPORT void startTrackingCompositingUpdates();
321     WEBCORE_EXPORT unsigned compositingUpdateCount() const;
322
323 private:
324     class OverlapMap;
325     struct CompositingState;
326     struct OverlapExtent;
327
328     // GraphicsLayerClient implementation
329     virtual void notifyFlushRequired(const GraphicsLayer*) override;
330     virtual void paintContents(const GraphicsLayer*, GraphicsContext&, GraphicsLayerPaintingPhase, const FloatRect&) override;
331     virtual void customPositionForVisibleRectComputation(const GraphicsLayer*, FloatPoint&) const override;
332     virtual bool isTrackingRepaints() const override;
333     
334     // GraphicsLayerUpdaterClient implementation
335     virtual void flushLayersSoon(GraphicsLayerUpdater&) override;
336
337     // Whether the given RL needs a compositing layer.
338     bool needsToBeComposited(const RenderLayer&, RenderLayer::ViewportConstrainedNotCompositedReason* = nullptr) const;
339     // Whether the layer has an intrinsic need for compositing layer.
340     bool requiresCompositingLayer(const RenderLayer&, RenderLayer::ViewportConstrainedNotCompositedReason* = nullptr) const;
341     // Whether the layer could ever be composited.
342     bool canBeComposited(const RenderLayer&) const;
343
344     // Make or destroy the backing for this layer; returns true if backing changed.
345     enum class BackingRequired { No, Yes, Unknown };
346     bool updateBacking(RenderLayer&, CompositingChangeRepaint shouldRepaint, BackingRequired = BackingRequired::Unknown);
347
348     void clearBackingForLayerIncludingDescendants(RenderLayer&);
349     void setIsInWindowForLayerIncludingDescendants(RenderLayer&, bool isInWindow);
350
351     // Repaint this and its child layers.
352     void recursiveRepaintLayer(RenderLayer&);
353
354     void computeExtent(const OverlapMap&, const RenderLayer&, OverlapExtent&) const;
355     void addToOverlapMap(OverlapMap&, const RenderLayer&, OverlapExtent&);
356     void addToOverlapMapRecursive(OverlapMap&, const RenderLayer&, const RenderLayer* ancestorLayer = nullptr);
357
358     void updateCompositingLayersTimerFired();
359
360     // Returns true if any layer's compositing changed
361     void computeCompositingRequirements(RenderLayer* ancestorLayer, RenderLayer&, OverlapMap&, CompositingState&, bool& layersChanged, bool& descendantHas3DTransform);
362
363     void computeRegionCompositingRequirements(RenderNamedFlowFragment*, OverlapMap&, CompositingState&, bool& layersChanged, bool& anyDescendantHas3DTransform);
364
365     void computeCompositingRequirementsForNamedFlowFixed(RenderLayer&, OverlapMap&, CompositingState&, bool& layersChanged, bool& anyDescendantHas3DTransform);
366
367     // Recurses down the tree, parenting descendant compositing layers and collecting an array of child layers for the current compositing layer.
368     void rebuildCompositingLayerTree(RenderLayer&, Vector<GraphicsLayer*>& childGraphicsLayersOfEnclosingLayer, int depth);
369
370     // Recurses down the RenderFlowThread tree, parenting descendant compositing layers and collecting an array of child 
371     // layers for the current compositing layer corresponding to the anonymous region (that belongs to the region's parent).
372     void rebuildRegionCompositingLayerTree(RenderNamedFlowFragment*, Vector<GraphicsLayer*>& childList, int depth);
373
374     void rebuildCompositingLayerTreeForNamedFlowFixed(RenderLayer&, Vector<GraphicsLayer*>& childList, int depth);
375
376     // Recurses down the tree, updating layer geometry only.
377     void updateLayerTreeGeometry(RenderLayer&, int depth);
378     
379     // Hook compositing layers together
380     void setCompositingParent(RenderLayer& childLayer, RenderLayer* parentLayer);
381     void removeCompositedChildren(RenderLayer&);
382
383     bool layerHas3DContent(const RenderLayer&) const;
384     bool isRunningTransformAnimation(RenderLayerModelObject&) const;
385
386     void appendDocumentOverlayLayers(Vector<GraphicsLayer*>&);
387     bool hasAnyAdditionalCompositedLayers(const RenderLayer& rootLayer) const;
388
389     void ensureRootLayer();
390     void destroyRootLayer();
391
392     void attachRootLayer(RootLayerAttachment);
393     void detachRootLayer();
394     
395     void rootLayerAttachmentChanged();
396
397     void updateOverflowControlsLayers();
398
399     void updateScrollLayerPosition();
400
401     FloatPoint positionForClipLayer() const;
402
403     void notifyIFramesOfCompositingChange();
404
405     bool isFlushingLayers() const { return m_flushingLayers; }
406     void updateScrollCoordinatedLayersAfterFlushIncludingSubframes();
407     void updateScrollCoordinatedLayersAfterFlush();
408     
409     Page* page() const;
410     
411     GraphicsLayerFactory* graphicsLayerFactory() const;
412     ScrollingCoordinator* scrollingCoordinator() const;
413
414 #if USE(REQUEST_ANIMATION_FRAME_DISPLAY_MONITOR)
415     RefPtr<DisplayRefreshMonitor> createDisplayRefreshMonitor(PlatformDisplayID) const override;
416 #endif
417
418     bool requiresCompositingForAnimation(RenderLayerModelObject&) const;
419     bool requiresCompositingForTransform(RenderLayerModelObject&) const;
420     bool requiresCompositingForBackfaceVisibility(RenderLayerModelObject&) const;
421     bool requiresCompositingForVideo(RenderLayerModelObject&) const;
422     bool requiresCompositingForCanvas(RenderLayerModelObject&) const;
423     bool requiresCompositingForPlugin(RenderLayerModelObject&) const;
424     bool requiresCompositingForFrame(RenderLayerModelObject&) const;
425     bool requiresCompositingForFilters(RenderLayerModelObject&) const;
426     bool requiresCompositingForScrollableFrame() const;
427     bool requiresCompositingForPosition(RenderLayerModelObject&, const RenderLayer&, RenderLayer::ViewportConstrainedNotCompositedReason* = nullptr) const;
428     bool requiresCompositingForOverflowScrolling(const RenderLayer&) const;
429     bool requiresCompositingForIndirectReason(RenderLayerModelObject&, bool hasCompositedDescendants, bool has3DTransformedDescendants, RenderLayer::IndirectCompositingReason&) const;
430
431 #if PLATFORM(IOS)
432     bool requiresCompositingForScrolling(const RenderLayer&) const;
433
434     void updateCustomLayersAfterFlush();
435
436     ChromeClient* chromeClient() const;
437
438 #endif
439
440     void updateScrollCoordinationForThisFrame(ScrollingNodeID);
441     ScrollingNodeID attachScrollingNode(RenderLayer&, ScrollingNodeType, ScrollingNodeID parentNodeID);
442     void updateScrollCoordinatedLayer(RenderLayer&, LayerScrollCoordinationRoles);
443     void detachScrollCoordinatedLayer(RenderLayer&, LayerScrollCoordinationRoles);
444     void reattachSubframeScrollLayers();
445     
446     FixedPositionViewportConstraints computeFixedViewportConstraints(RenderLayer&) const;
447     StickyPositionViewportConstraints computeStickyViewportConstraints(RenderLayer&) const;
448
449     bool requiresScrollLayer(RootLayerAttachment) const;
450     bool requiresHorizontalScrollbarLayer() const;
451     bool requiresVerticalScrollbarLayer() const;
452     bool requiresScrollCornerLayer() const;
453 #if ENABLE(RUBBER_BANDING)
454     bool requiresOverhangAreasLayer() const;
455     bool requiresContentShadowLayer() const;
456 #endif
457
458     // True if the FrameView uses a ScrollingCoordinator.
459     bool hasCoordinatedScrolling() const;
460
461     bool isAsyncScrollableStickyLayer(const RenderLayer&, const RenderLayer** enclosingAcceleratedOverflowLayer = nullptr) const;
462     bool isViewportConstrainedFixedOrStickyLayer(const RenderLayer&) const;
463     
464     bool shouldCompositeOverflowControls() const;
465
466     void scheduleLayerFlushNow();
467     bool isThrottlingLayerFlushes() const;
468     void startInitialLayerFlushTimerIfNeeded();
469     void startLayerFlushTimerIfNeeded();
470     void layerFlushTimerFired();
471
472     void paintRelatedMilestonesTimerFired();
473
474 #if !LOG_DISABLED
475     const char* logReasonsForCompositing(const RenderLayer&);
476     void logLayerInfo(const RenderLayer&, int depth);
477 #endif
478
479     bool mainFrameBackingIsTiled() const;
480
481 private:
482     RenderView& m_renderView;
483     std::unique_ptr<GraphicsLayer> m_rootContentLayer;
484     Timer m_updateCompositingLayersTimer;
485
486     bool m_hasAcceleratedCompositing;
487     ChromeClient::CompositingTriggerFlags m_compositingTriggers;
488
489     bool m_showDebugBorders;
490     bool m_showRepaintCounter;
491     bool m_acceleratedDrawingEnabled;
492
493     // When true, we have to wait until layout has happened before we can decide whether to enter compositing mode,
494     // because only then do we know the final size of plugins and iframes.
495     mutable bool m_reevaluateCompositingAfterLayout;
496
497     bool m_compositing;
498     bool m_compositingLayersNeedRebuild;
499     bool m_flushingLayers;
500     bool m_shouldFlushOnReattach;
501     bool m_forceCompositingMode;
502     bool m_inPostLayoutUpdate; // true when it's OK to trust layout information (e.g. layer sizes and positions)
503     bool m_subframeScrollLayersNeedReattach;
504
505     bool m_isTrackingRepaints; // Used for testing.
506
507     int m_compositedLayerCount { 0 };
508     unsigned m_layersWithTiledBackingCount { 0 };
509     unsigned m_layerFlushCount { 0 };
510     unsigned m_compositingUpdateCount { 0 };
511
512     RootLayerAttachment m_rootLayerAttachment;
513
514     // Enclosing clipping layer for iframe content
515     std::unique_ptr<GraphicsLayer> m_clipLayer;
516     std::unique_ptr<GraphicsLayer> m_scrollLayer;
517
518 #if PLATFORM(IOS)
519     HashSet<RenderLayer*> m_scrollingLayers;
520     HashSet<RenderLayer*> m_scrollingLayersNeedingUpdate;
521 #endif
522     HashSet<RenderLayer*> m_scrollCoordinatedLayers;
523     HashSet<RenderLayer*> m_scrollCoordinatedLayersNeedingUpdate;
524
525     // Enclosing layer for overflow controls and the clipping layer
526     std::unique_ptr<GraphicsLayer> m_overflowControlsHostLayer;
527
528     // Layers for overflow controls
529     std::unique_ptr<GraphicsLayer> m_layerForHorizontalScrollbar;
530     std::unique_ptr<GraphicsLayer> m_layerForVerticalScrollbar;
531     std::unique_ptr<GraphicsLayer> m_layerForScrollCorner;
532 #if ENABLE(RUBBER_BANDING)
533     std::unique_ptr<GraphicsLayer> m_layerForOverhangAreas;
534     std::unique_ptr<GraphicsLayer> m_contentShadowLayer;
535     std::unique_ptr<GraphicsLayer> m_layerForTopOverhangArea;
536     std::unique_ptr<GraphicsLayer> m_layerForBottomOverhangArea;
537     std::unique_ptr<GraphicsLayer> m_layerForHeader;
538     std::unique_ptr<GraphicsLayer> m_layerForFooter;
539 #endif
540
541     std::unique_ptr<GraphicsLayerUpdater> m_layerUpdater; // Updates tiled layer visible area periodically while animations are running.
542
543     Timer m_layerFlushTimer;
544     bool m_layerFlushThrottlingEnabled;
545     bool m_layerFlushThrottlingTemporarilyDisabledForInteraction;
546     bool m_hasPendingLayerFlush;
547     bool m_layerNeedsCompositingUpdate { false };
548
549     Timer m_paintRelatedMilestonesTimer;
550
551 #if !LOG_DISABLED
552     int m_rootLayerUpdateCount { 0 };
553     int m_obligateCompositedLayerCount { 0 }; // count of layer that have to be composited.
554     int m_secondaryCompositedLayerCount { 0 }; // count of layers that have to be composited because of stacking or overlap.
555     double m_obligatoryBackingStoreBytes { 0 };
556     double m_secondaryBackingStoreBytes { 0 };
557 #endif
558
559     Color m_rootExtendedBackgroundColor;
560     Color m_lastDocumentBackgroundColor;
561
562     HashMap<ScrollingNodeID, RenderLayer*> m_scrollingNodeToLayerMap;
563 };
564
565
566 } // namespace WebCore
567
568 #endif // RenderLayerCompositor_h