Revert 114283 - Avoid using backing store for compositing layers that just need to clip

Source/WebCore/rendering/RenderLayerBacking.cpp

 /*
  * Copyright (C) 2009, 2010, 2011 Apple 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 74 matching lines @@
     UNUSED_PARAM(renderer);
 #endif
     return false;
 }
 
 RenderLayerBacking::RenderLayerBacking(RenderLayer* layer)
     : m_owningLayer(layer)
     , m_artificiallyInflatedBounds(false)
     , m_isMainFrameRenderViewLayer(false)
     , m_usingTiledCacheLayer(false)
-    , m_requiresOwnBackingStore(true)
 #if ENABLE(CSS_FILTERS)
     , m_canCompositeFilters(false)
 #endif
 {
     if (renderer()->isRenderView()) {
         Frame* frame = toRenderView(renderer())->frameView()->frame();
         Page* page = frame ? frame->page() : 0;
         if (page && frame && page->mainFrame() == frame) {
             m_isMainFrameRenderViewLayer = true;
 
@@ skipping 453 matching lines @@
         reflectionBacking->updateGraphicsLayerGeometry();
         
         // The reflection layer has the bounds of m_owningLayer->reflectionLayer(),
         // but the reflected layer is the bounds of this layer, so we need to position it appropriately.
         FloatRect layerBounds = compositedBounds();
         FloatRect reflectionLayerBounds = reflectionBacking->compositedBounds();
         reflectionBacking->graphicsLayer()->setReplicatedLayerPosition(FloatPoint() + (layerBounds.location() - reflectionLayerBounds.location()));
     }
 
     m_graphicsLayer->setContentsRect(contentsBox());
-
-    // If this layer was created just for clipping or to apply perspective, it doesn't need its own backing store.
-    setRequiresOwnBackingStore(compositor()->requiresOwnBackingStore(m_owningLayer, compAncestor));
-
     updateDrawsContent();
     updateAfterWidgetResize();
 }
 
 void RenderLayerBacking::updateInternalHierarchy()
 {
     // m_foregroundLayer has to be inserted in the correct order with child layers,
     // so it's not inserted here.
     if (m_ancestorClippingLayer) {
         m_ancestorClippingLayer->removeAllChildren();
@@ skipping 359 matching lines @@
                     return true;
             }
         }
     }
 
     return false;
 }
 
 bool RenderLayerBacking::containsPaintedContent() const
 {
-    if (isSimpleContainerCompositingLayer() || paintsIntoWindow() || paintsIntoCompositedAncestor() || m_artificiallyInflatedBounds || m_owningLayer->isReflection())
+    if (isSimpleContainerCompositingLayer() || paintsIntoWindow() || m_artificiallyInflatedBounds || m_owningLayer->isReflection())
         return false;
 
     if (isDirectlyCompositedImage())
         return false;
 
     // FIXME: we could optimize cases where the image, video or canvas is known to fill the border box entirely,
     // and set background color on the layer in that case, instead of allocating backing store and painting.
 #if ENABLE(VIDEO)
     if (renderer()->isVideo() && toRenderVideo(renderer())->shouldDisplayVideo())
         return hasBoxDecorationsOrBackground(renderer());
@@ skipping 137 matching lines @@
 #endif
 
         return compositor()->rootLayerAttachment() != RenderLayerCompositor::RootLayerAttachedViaEnclosingFrame;
     }
     
     return false;
 }
 
 void RenderLayerBacking::setContentsNeedDisplay()
 {
-    ASSERT(!paintsIntoCompositedAncestor());
-    
     if (m_graphicsLayer && m_graphicsLayer->drawsContent())
         m_graphicsLayer->setNeedsDisplay();
     
     if (m_foregroundLayer && m_foregroundLayer->drawsContent())
         m_foregroundLayer->setNeedsDisplay();
 
     if (m_maskLayer && m_maskLayer->drawsContent())
         m_maskLayer->setNeedsDisplay();
 }
 
 // r is in the coordinate space of the layer's render object
 void RenderLayerBacking::setContentsNeedDisplayInRect(const IntRect& r)
 {
-    ASSERT(!paintsIntoCompositedAncestor());
-
     if (m_graphicsLayer && m_graphicsLayer->drawsContent()) {
         IntRect layerDirtyRect = r;
         layerDirtyRect.move(-m_graphicsLayer->offsetFromRenderer());
         m_graphicsLayer->setNeedsDisplayInRect(layerDirtyRect);
     }
 
     if (m_foregroundLayer && m_foregroundLayer->drawsContent()) {
         IntRect layerDirtyRect = r;
         layerDirtyRect.move(-m_foregroundLayer->offsetFromRenderer());
         m_foregroundLayer->setNeedsDisplayInRect(layerDirtyRect);
     }
 
     if (m_maskLayer && m_maskLayer->drawsContent()) {
         IntRect layerDirtyRect = r;
         layerDirtyRect.move(-m_maskLayer->offsetFromRenderer());
         m_maskLayer->setNeedsDisplayInRect(layerDirtyRect);
     }
 }
 
 void RenderLayerBacking::paintIntoLayer(RenderLayer* rootLayer, GraphicsContext* context,
                     const IntRect& paintDirtyRect, // In the coords of rootLayer.
                     PaintBehavior paintBehavior, GraphicsLayerPaintingPhase paintingPhase,
                     RenderObject* paintingRoot)
 {
-    if (paintsIntoWindow() || paintsIntoCompositedAncestor()) {
+    if (paintsIntoWindow()) {
         ASSERT_NOT_REACHED();
         return;
     }
 
     FontCachePurgePreventer fontCachePurgePreventer;
     
     RenderLayer::PaintLayerFlags paintFlags = 0;
     if (paintingPhase & GraphicsLayerPaintBackground)
         paintFlags |= RenderLayer::PaintLayerPaintingCompositingBackgroundPhase;
     if (paintingPhase & GraphicsLayerPaintForeground)
@@ skipping 387 matching lines @@
     if (m_layerForScrollCorner)
         backingArea += m_layerForScrollCorner->backingStoreArea();
     
     return backingArea;
 }
 
 } // namespace WebCore
 
 #endif // USE(ACCELERATED_COMPOSITING)