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      1 /*
      2  * Copyright (C) 2009 Apple Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
     14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
     17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 #ifndef RenderLayerCompositor_h
     27 #define RenderLayerCompositor_h
     28 
     29 #include "ChromeClient.h"
     30 #include "RenderLayer.h"
     31 #include "RenderLayerBacking.h"
     32 
     33 namespace WebCore {
     34 
     35 #define PROFILE_LAYER_REBUILD 0
     36 
     37 class GraphicsLayer;
     38 class RenderEmbeddedObject;
     39 class RenderPart;
     40 #if ENABLE(VIDEO)
     41 class RenderVideo;
     42 #endif
     43 
     44 enum CompositingUpdateType {
     45     CompositingUpdateAfterLayoutOrStyleChange,
     46     CompositingUpdateOnPaitingOrHitTest,
     47     CompositingUpdateOnScroll
     48 };
     49 
     50 // RenderLayerCompositor manages the hierarchy of
     51 // composited RenderLayers. It determines which RenderLayers
     52 // become compositing, and creates and maintains a hierarchy of
     53 // GraphicsLayers based on the RenderLayer painting order.
     54 //
     55 // There is one RenderLayerCompositor per RenderView.
     56 
     57 class RenderLayerCompositor : public GraphicsLayerClient {
     58 public:
     59     RenderLayerCompositor(RenderView*);
     60     ~RenderLayerCompositor();
     61 
     62     // Return true if this RenderView is in "compositing mode" (i.e. has one or more
     63     // composited RenderLayers)
     64     bool inCompositingMode() const { return m_compositing; }
     65     // This will make a compositing layer at the root automatically, and hook up to
     66     // the native view/window system.
     67     void enableCompositingMode(bool enable = true);
     68 
     69     // Returns true if the accelerated compositing is enabled
     70     bool hasAcceleratedCompositing() const { return m_hasAcceleratedCompositing; }
     71 
     72     bool canRender3DTransforms() const;
     73 
     74     // Copy the accelerated compositing related flags from Settings
     75     void cacheAcceleratedCompositingFlags();
     76 
     77     // Called when the layer hierarchy needs to be updated (compositing layers have been
     78     // created, destroyed or re-parented).
     79     void setCompositingLayersNeedRebuild(bool needRebuild = true);
     80     bool compositingLayersNeedRebuild() const { return m_compositingLayersNeedRebuild; }
     81 
     82     // Controls whether or not to consult geometry when deciding which layers need
     83     // to be composited. Defaults to true.
     84     void setCompositingConsultsOverlap(bool b) { m_compositingConsultsOverlap = b; }
     85     bool compositingConsultsOverlap() const { return m_compositingConsultsOverlap; }
     86 
     87     // GraphicsLayers buffer state, which gets pushed to the underlying platform layers
     88     // at specific times.
     89     void scheduleLayerFlush();
     90     void flushPendingLayerChanges();
     91     bool isFlushingLayers() const { return m_flushingLayers; }
     92 
     93     // flushPendingLayerChanges() flushes the entire GraphicsLayer tree, which can cross frame boundaries.
     94     // This call returns the rootmost compositor that is being flushed (including self).
     95     RenderLayerCompositor* enclosingCompositorFlushingLayers() const;
     96 
     97     // Rebuild the tree of compositing layers
     98     void updateCompositingLayers(CompositingUpdateType = CompositingUpdateAfterLayoutOrStyleChange, RenderLayer* updateRoot = 0);
     99     // This is only used when state changes and we do not exepect a style update or layout to happen soon (e.g. when
    100     // we discover that an iframe is overlapped during painting).
    101     void scheduleCompositingLayerUpdate();
    102     bool compositingLayerUpdatePending() const;
    103 
    104     // Update the compositing state of the given layer. Returns true if that state changed.
    105     enum CompositingChangeRepaint { CompositingChangeRepaintNow, CompositingChangeWillRepaintLater };
    106     bool updateLayerCompositingState(RenderLayer*, CompositingChangeRepaint = CompositingChangeRepaintNow);
    107 
    108     // Update the geometry for compositing children of compositingAncestor.
    109     void updateCompositingDescendantGeometry(RenderLayer* compositingAncestor, RenderLayer* layer, RenderLayerBacking::UpdateDepth);
    110 
    111     // Whether layer's backing needs a graphics layer to do clipping by an ancestor (non-stacking-context parent with overflow).
    112     bool clippedByAncestor(RenderLayer*) const;
    113     // Whether layer's backing needs a graphics layer to clip z-order children of the given layer.
    114     bool clipsCompositingDescendants(const RenderLayer*) const;
    115 
    116     // Whether the given layer needs an extra 'contents' layer.
    117     bool needsContentsCompositingLayer(const RenderLayer*) const;
    118     // Return the bounding box required for compositing layer and its childern, relative to ancestorLayer.
    119     // If layerBoundingBox is not 0, on return it contains the bounding box of this layer only.
    120     IntRect calculateCompositedBounds(const RenderLayer* layer, const RenderLayer* ancestorLayer);
    121 
    122     // Repaint the appropriate layers when the given RenderLayer starts or stops being composited.
    123     void repaintOnCompositingChange(RenderLayer*);
    124 
    125     // Notify us that a layer has been added or removed
    126     void layerWasAdded(RenderLayer* parent, RenderLayer* child);
    127     void layerWillBeRemoved(RenderLayer* parent, RenderLayer* child);
    128 
    129     // Get the nearest ancestor layer that has overflow or clip, but is not a stacking context
    130     RenderLayer* enclosingNonStackingClippingLayer(const RenderLayer* layer) const;
    131 
    132     // Repaint parts of all composited layers that intersect the given absolute rectangle.
    133     void repaintCompositedLayersAbsoluteRect(const IntRect&);
    134 
    135     RenderLayer* rootRenderLayer() const;
    136     GraphicsLayer* rootPlatformLayer() const;
    137 
    138     enum RootLayerAttachment {
    139         RootLayerUnattached,
    140         RootLayerAttachedViaChromeClient,
    141         RootLayerAttachedViaEnclosingFrame
    142     };
    143 
    144     RootLayerAttachment rootLayerAttachment() const { return m_rootLayerAttachment; }
    145     void updateRootLayerAttachment();
    146     void updateRootLayerPosition();
    147 
    148     void didMoveOnscreen();
    149     void willMoveOffscreen();
    150 
    151     void didStartAcceleratedAnimation(CSSPropertyID);
    152 
    153 #if ENABLE(VIDEO)
    154     // Use by RenderVideo to ask if it should try to use accelerated compositing.
    155     bool canAccelerateVideoRendering(RenderVideo*) const;
    156 #endif
    157 
    158     // Walk the tree looking for layers with 3d transforms. Useful in case you need
    159     // to know if there is non-affine content, e.g. for drawing into an image.
    160     bool has3DContent() const;
    161 
    162     // Most platforms connect compositing layer trees between iframes and their parent document.
    163     // Some (currently just Mac) allow iframes to do their own compositing.
    164     static bool allowsIndependentlyCompositedFrames(const FrameView*);
    165     bool shouldPropagateCompositingToEnclosingFrame() const;
    166 
    167     HTMLFrameOwnerElement* enclosingFrameElement() const;
    168 
    169     static RenderLayerCompositor* frameContentsCompositor(RenderPart*);
    170     // Return true if the layers changed.
    171     static bool parentFrameContentLayers(RenderPart*);
    172 
    173     // Update the geometry of the layers used for clipping and scrolling in frames.
    174     void frameViewDidChangeLocation(const IntPoint& contentsOffset);
    175     void frameViewDidChangeSize();
    176     void frameViewDidScroll(const IntPoint& = IntPoint());
    177 
    178     String layerTreeAsText(bool showDebugInfo = false);
    179 
    180     // These are named to avoid conflicts with the functions in GraphicsLayerClient
    181     // These return the actual internal variables.
    182     bool compositorShowDebugBorders() const { return m_showDebugBorders; }
    183     bool compositorShowRepaintCounter() const { return m_showRepaintCounter; }
    184 
    185     void updateContentsScale(float, RenderLayer* = 0);
    186 
    187     GraphicsLayer* layerForHorizontalScrollbar() const { return m_layerForHorizontalScrollbar.get(); }
    188     GraphicsLayer* layerForVerticalScrollbar() const { return m_layerForVerticalScrollbar.get(); }
    189     GraphicsLayer* layerForScrollCorner() const { return m_layerForScrollCorner.get(); }
    190 
    191 private:
    192     // GraphicsLayerClient Implementation
    193     virtual void notifyAnimationStarted(const GraphicsLayer*, double) { }
    194     virtual void notifySyncRequired(const GraphicsLayer*) { scheduleLayerFlush(); }
    195     virtual void paintContents(const GraphicsLayer*, GraphicsContext&, GraphicsLayerPaintingPhase, const IntRect&);
    196 
    197     // These calls return false always. They are saying that the layers associated with this client
    198     // (the clipLayer and scrollLayer) should never show debugging info.
    199     virtual bool showDebugBorders() const { return false; }
    200     virtual bool showRepaintCounter() const { return false; }
    201 
    202     // Whether the given RL needs a compositing layer.
    203     bool needsToBeComposited(const RenderLayer*) const;
    204     // Whether the layer has an intrinsic need for compositing layer.
    205     bool requiresCompositingLayer(const RenderLayer*) const;
    206     // Whether the layer could ever be composited.
    207     bool canBeComposited(const RenderLayer*) const;
    208 
    209     // Make or destroy the backing for this layer; returns true if backing changed.
    210     bool updateBacking(RenderLayer*, CompositingChangeRepaint shouldRepaint);
    211 
    212     // Repaint the given rect (which is layer's coords), and regions of child layers that intersect that rect.
    213     void recursiveRepaintLayerRect(RenderLayer* layer, const IntRect& rect);
    214 
    215     typedef HashMap<RenderLayer*, IntRect> OverlapMap;
    216     static void addToOverlapMap(OverlapMap&, RenderLayer*, IntRect& layerBounds, bool& boundsComputed);
    217     static bool overlapsCompositedLayers(OverlapMap&, const IntRect& layerBounds);
    218 
    219     void updateCompositingLayersTimerFired(Timer<RenderLayerCompositor>*);
    220 
    221 #if ENABLE(COMPOSITED_FIXED_ELEMENTS)
    222     bool checkForPositionedElements(Vector<RenderLayer*>* list);
    223 #endif
    224 
    225     // Returns true if any layer's compositing changed
    226     void computeCompositingRequirements(RenderLayer*, OverlapMap*, struct CompositingState&, bool& layersChanged);
    227 
    228     // Recurses down the tree, parenting descendant compositing layers and collecting an array of child layers for the current compositing layer.
    229     void rebuildCompositingLayerTree(RenderLayer* layer, const struct CompositingState&, Vector<GraphicsLayer*>& childGraphicsLayersOfEnclosingLayer);
    230 
    231     // Recurses down the tree, updating layer geometry only.
    232     void updateLayerTreeGeometry(RenderLayer*);
    233 
    234     // Hook compositing layers together
    235     void setCompositingParent(RenderLayer* childLayer, RenderLayer* parentLayer);
    236     void removeCompositedChildren(RenderLayer*);
    237 
    238     bool layerHas3DContent(const RenderLayer*) const;
    239 
    240     void ensureRootPlatformLayer();
    241     void destroyRootPlatformLayer();
    242 
    243     void attachRootPlatformLayer(RootLayerAttachment);
    244     void detachRootPlatformLayer();
    245 
    246     void rootLayerAttachmentChanged();
    247 
    248     void updateOverflowControlsLayers();
    249 
    250     void scheduleNeedsStyleRecalc(Element*);
    251     void notifyIFramesOfCompositingChange();
    252 
    253     // Whether a running transition or animation enforces the need for a compositing layer.
    254     bool requiresCompositingForAnimation(RenderObject*) const;
    255     bool requiresCompositingForTransform(RenderObject*) const;
    256     bool requiresCompositingForVideo(RenderObject*) const;
    257     bool requiresCompositingForCanvas(RenderObject*) const;
    258     bool requiresCompositingForPlugin(RenderObject*) const;
    259     bool requiresCompositingForFrame(RenderObject*) const;
    260     bool requiresCompositingWhenDescendantsAreCompositing(RenderObject*) const;
    261     bool requiresCompositingForFullScreen(RenderObject*) const;
    262 
    263 #if PLATFORM(ANDROID)
    264     // Whether we are using layers for new android features (overflow support, fixed elements)
    265     bool requiresCompositingForAndroidLayers(const RenderLayer* layer) const;
    266 #endif
    267 
    268     bool requiresScrollLayer(RootLayerAttachment) const;
    269     bool requiresHorizontalScrollbarLayer() const;
    270     bool requiresVerticalScrollbarLayer() const;
    271     bool requiresScrollCornerLayer() const;
    272 
    273 private:
    274     RenderView* m_renderView;
    275     OwnPtr<GraphicsLayer> m_rootPlatformLayer;
    276     Timer<RenderLayerCompositor> m_updateCompositingLayersTimer;
    277 
    278     bool m_hasAcceleratedCompositing;
    279     ChromeClient::CompositingTriggerFlags m_compositingTriggers;
    280 
    281     bool m_showDebugBorders;
    282     bool m_showRepaintCounter;
    283     bool m_compositingConsultsOverlap;
    284 
    285     // When true, we have to wait until layout has happened before we can decide whether to enter compositing mode,
    286     // because only then do we know the final size of plugins and iframes.
    287     // FIXME: once set, this is never cleared.
    288     mutable bool m_compositingDependsOnGeometry;
    289 
    290     bool m_compositing;
    291     bool m_compositingLayersNeedRebuild;
    292     bool m_flushingLayers;
    293     bool m_forceCompositingMode;
    294 
    295     RootLayerAttachment m_rootLayerAttachment;
    296 
    297     // Enclosing clipping layer for iframe content
    298     OwnPtr<GraphicsLayer> m_clipLayer;
    299     OwnPtr<GraphicsLayer> m_scrollLayer;
    300 
    301     // Enclosing layer for overflow controls and the clipping layer
    302     OwnPtr<GraphicsLayer> m_overflowControlsHostLayer;
    303 
    304     // Layers for overflow controls
    305     OwnPtr<GraphicsLayer> m_layerForHorizontalScrollbar;
    306     OwnPtr<GraphicsLayer> m_layerForVerticalScrollbar;
    307     OwnPtr<GraphicsLayer> m_layerForScrollCorner;
    308 #if PROFILE_LAYER_REBUILD
    309     int m_rootLayerUpdateCount;
    310 #endif
    311 };
    312 
    313 
    314 } // namespace WebCore
    315 
    316 #endif // RenderLayerCompositor_h
    317