Drop background color optimization for composited layers

Source/core/rendering/compositing/CompositedLayerMapping.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 327 matching lines @@
     if (m_owningLayer->renderer()->containingBlock()->enclosingLayer() != m_owningLayer->ancestorScrollingLayer())
         return true;
 
     return false;
 }
 
 void CompositedLayerMapping::updateCompositedBounds()
 {
     // We need to know if we draw content in order to update our bounds (this has an effect
     // on whether or not descendands will paint into our backing). Update this value now.
-    updateDrawsContent(isSimpleContainerCompositingLayer());
+    updateDrawsContent();
 
     LayoutRect layerBounds = compositor()->calculateCompositedBounds(m_owningLayer, m_owningLayer);
 
     // Clip to the size of the document or enclosing overflow-scroll layer.
     // If this or an ancestor is transformed, we can't currently compute the correct rect to intersect with.
     // We'd need RenderObject::convertContainerToLocalQuad(), which doesn't yet exist.
     if (shouldClipCompositedBounds()) {
         RenderView* view = m_owningLayer->renderer()->view();
         RenderLayer* rootLayer = view->layer();
 
@@ skipping 147 matching lines @@
 
     if (m_owningLayer->reflectionInfo()) {
         if (m_owningLayer->reflectionInfo()->reflectionLayer()->hasCompositedLayerMapping()) {
             GraphicsLayer* reflectionLayer = m_owningLayer->reflectionInfo()->reflectionLayer()->compositedLayerMapping()->mainGraphicsLayer();
             m_graphicsLayer->setReplicatedByLayer(reflectionLayer);
         }
     } else {
         m_graphicsLayer->setReplicatedByLayer(0);
     }
 
-    updateBackgroundColor(isSimpleContainerCompositingLayer());
+    updateBackgroundColor();
 
     if (isDirectlyCompositedImage())
         updateImageContents();
 
     if (renderer->isEmbeddedObject() && toRenderEmbeddedObject(renderer)->allowsAcceleratedCompositing()) {
         PluginView* pluginView = toPluginView(toRenderWidget(renderer)->widget());
         m_graphicsLayer->setContentsToPlatformLayer(pluginView->platformLayer());
     } else if (renderer->node() && renderer->node()->isFrameOwnerElement() && toHTMLFrameOwnerElement(renderer->node())->contentFrame()) {
         blink::WebLayer* layer = toHTMLFrameOwnerElement(renderer->node())->contentFrame()->remotePlatformLayer();
         if (layer)
@@ skipping 97 matching lines @@
 
     // Set transform property, if it is not animating. We have to do this here because the transform
     // is affected by the layer dimensions.
     if (!hasActiveAnimationsOnCompositor(*renderer(), CSSPropertyWebkitTransform))
         updateTransform(renderer()->style());
 
     // Set opacity, if it is not animating.
     if (!hasActiveAnimationsOnCompositor(*renderer(), CSSPropertyOpacity))
         updateOpacity(renderer()->style());
 
-    bool isSimpleContainer = isSimpleContainerCompositingLayer();
-
     m_owningLayer->updateDescendantDependentFlags();
 
     // m_graphicsLayer is the corresponding GraphicsLayer for this RenderLayer and its non-compositing
     // descendants. So, the visibility flag for m_graphicsLayer should be true if there are any
     // non-compositing visible layers.
     bool contentsVisible = m_owningLayer->hasVisibleContent() || hasVisibleNonCompositingDescendantLayers();
     if (RuntimeEnabledFeatures::overlayFullscreenVideoEnabled() && renderer()->isVideo()) {
         HTMLMediaElement* mediaElement = toHTMLMediaElement(renderer()->node());
         if (mediaElement->isFullscreen())
             contentsVisible = false;
@@ skipping 200 matching lines @@
 
     // We can't make this call in RenderLayerCompositor::allocateOrClearCompositedLayerMapping
     // since it depends on whether compAncestor draws content, which gets updated later.
     updateRequiresOwnBackingStoreForAncestorReasons(compAncestor);
 
     if (RuntimeEnabledFeatures::cssCompositingEnabled()) {
         updateLayerBlendMode(style);
         updateIsRootForIsolatedGroup();
     }
 
-    updateContentsRect(isSimpleContainer);
-    updateBackgroundColor(isSimpleContainer);
-    updateDrawsContent(isSimpleContainer);
+    updateContentsRect();
+    updateBackgroundColor();
+    updateDrawsContent();
     updateContentsOpaque();
     updateAfterWidgetResize();
     updateRenderingContext();
     updateShouldFlattenTransform();
     updateChildrenTransform();
     registerScrollingLayers();
 
     updateCompositingReasons();
 }
 
@@ skipping 64 matching lines @@
 
         if (m_ancestorClippingLayer)
             m_squashingContainmentLayer->addChild(m_ancestorClippingLayer.get());
         else
             m_squashingContainmentLayer->addChild(m_graphicsLayer.get());
 
         m_squashingContainmentLayer->addChild(m_squashingLayer.get());
     }
 }
 
-void CompositedLayerMapping::updateContentsRect(bool isSimpleContainer)
+void CompositedLayerMapping::updateContentsRect()
 {
-    LayoutRect contentsRect;
-    if (isSimpleContainer && renderer()->hasBackground())
-        contentsRect = backgroundBox();
-    else
-        contentsRect = contentsBox();
-
-    m_graphicsLayer->setContentsRect(pixelSnappedIntRect(contentsRect));
+    m_graphicsLayer->setContentsRect(pixelSnappedIntRect(contentsBox()));
 }
 
-void CompositedLayerMapping::updateDrawsContent(bool isSimpleContainer)
+void CompositedLayerMapping::updateDrawsContent()
 {
     if (m_scrollingLayer) {
         // We don't have to consider overflow controls, because we know that the scrollbars are drawn elsewhere.
         // m_graphicsLayer only needs backing store if the non-scrolling parts (background, outlines, borders, shadows etc) need to paint.
         // m_scrollingLayer never has backing store.
         // m_scrollingContentsLayer only needs backing store if the scrolled contents need to paint.
         bool hasNonScrollingPaintedContent = m_owningLayer->hasVisibleContent() && m_owningLayer->hasBoxDecorationsOrBackground();
         m_graphicsLayer->setDrawsContent(hasNonScrollingPaintedContent);
 
         bool hasScrollingPaintedContent = m_owningLayer->hasVisibleContent() && (renderer()->hasBackground() || paintsChildren());
         m_scrollingContentsLayer->setDrawsContent(hasScrollingPaintedContent);
         return;
     }
 
-    bool hasPaintedContent = containsPaintedContent(isSimpleContainer);
+    bool hasPaintedContent = containsPaintedContent();
     if (hasPaintedContent && isAcceleratedCanvas(renderer())) {
         CanvasRenderingContext* context = toHTMLCanvasElement(renderer()->node())->renderingContext();
         // Content layer may be null if context is lost.
         if (blink::WebLayer* contentLayer = context->platformLayer()) {
             Color bgColor(Color::transparent);
             if (contentLayerSupportsDirectBackgroundComposition(renderer())) {
                 bgColor = rendererBackgroundColor();
                 hasPaintedContent = false;
             }
             contentLayer->setBackgroundColor(bgColor.rgb());
@@ skipping 513 matching lines @@
 
 Color CompositedLayerMapping::rendererBackgroundColor() const
 {
     RenderObject* backgroundRenderer = renderer();
     if (backgroundRenderer->isRoot())
         backgroundRenderer = backgroundRenderer->rendererForRootBackground();
 
     return backgroundRenderer->resolveColor(CSSPropertyBackgroundColor);
 }
 
-void CompositedLayerMapping::updateBackgroundColor(bool isSimpleContainer)
+void CompositedLayerMapping::updateBackgroundColor()
 {
-    Color backgroundColor = rendererBackgroundColor();
-    if (isSimpleContainer) {
-        m_graphicsLayer->setContentsToSolidColor(backgroundColor);
-        m_graphicsLayer->setBackgroundColor(Color::transparent);
-    } else {
-        m_graphicsLayer->setContentsToSolidColor(Color::transparent);
-        m_graphicsLayer->setBackgroundColor(backgroundColor);
-    }
-}
-
-static bool supportsDirectBoxDecorationsComposition(const RenderObject* renderer)
-{
-    if (renderer->hasClip())
-        return false;
-
-    if (hasBoxDecorationsOrBackgroundImage(renderer->style()))
-        return false;
-
-    // FIXME: we should be able to allow backgroundComposite; However since this is not a common use case it has been deferred for now.
-    if (renderer->style()->backgroundComposite() != CompositeSourceOver)
-        return false;
-
-    if (renderer->style()->backgroundClip() == TextFillBox)
-        return false;
-
-    return true;
-}
-
-bool CompositedLayerMapping::paintsBoxDecorations() const
-{
-    if (!m_owningLayer->hasVisibleBoxDecorations())
-        return false;
-
-    if (!supportsDirectBoxDecorationsComposition(renderer()))
-        return true;
-
-    return false;
+    m_graphicsLayer->setBackgroundColor(rendererBackgroundColor());
 }
 
 bool CompositedLayerMapping::paintsChildren() const
 {
     if (m_owningLayer->hasVisibleContent() && m_owningLayer->hasNonEmptyChildRenderers())
         return true;
 
     if (hasVisibleNonCompositingDescendantLayers())
         return true;
 
     return false;
 }
 
 static bool isCompositedPlugin(RenderObject* renderer)
 {
     return renderer->isEmbeddedObject() && toRenderEmbeddedObject(renderer)->allowsAcceleratedCompositing();
 }
 
-// A "simple container layer" is a RenderLayer which has no visible content to render.
-// It may have no children, or all its children may be themselves composited.
-// This is a useful optimization, because it allows us to avoid allocating backing store.
-bool CompositedLayerMapping::isSimpleContainerCompositingLayer() const
+// FIXME: it's O(n^2). A better solution is needed.
+bool CompositedLayerMapping::hasVisibleContentOrNonCompositingDescendantLayers() const
 {
     RenderObject* renderObject = renderer();
     if (renderObject->hasMask()) // masks require special treatment
-        return false;
+        return true;
 
     if (renderObject->isReplaced() && !isCompositedPlugin(renderObject))
-        return false;
+        return true;
 
-    if (paintsBoxDecorations() || paintsChildren())
-        return false;
+    if (m_owningLayer->hasVisibleBoxDecorations() || paintsChildren())
+        return true;
 
     if (renderObject->isRenderRegion())
-        return false;
+        return true;
 
     if (renderObject->node() && renderObject->node()->isDocumentNode()) {
         // Look to see if the root object has a non-simple background
         RenderObject* rootObject = renderObject->document().documentElement() ? renderObject->document().documentElement()->renderer() : 0;
         if (!rootObject)
             return false;
 
         RenderStyle* style = rootObject->style();
 
         // Reject anything that has a border, a border-radius or outline,
         // or is not a simple background (no background, or solid color).
         if (hasBoxDecorationsOrBackgroundImage(style))
-            return false;
+            return true;
 
         // Now look at the body's renderer.
         HTMLElement* body = renderObject->document().body();
         RenderObject* bodyObject = (body && body->hasLocalName(bodyTag)) ? body->renderer() : 0;
         if (!bodyObject)
             return false;
 
         style = bodyObject->style();
 
         if (hasBoxDecorationsOrBackgroundImage(style))
-            return false;
+            return true;
     }
-
-    return true;
+    return false;
 }
 
 static bool hasVisibleNonCompositingDescendant(RenderLayer* parent)
 {
     // FIXME: We shouldn't be called with a stale z-order lists. See bug 85512.
     parent->stackingNode()->updateLayerListsIfNeeded();
 
 #if !ASSERT_DISABLED
     LayerListMutationDetector mutationChecker(parent->stackingNode());
 #endif
@@ skipping 21 matching lines @@
 }
 
 // FIXME: By name the implementation is correct. But the code that uses this function means something
 // very slightly different - the implementation needs to also include composited descendants that
 // don't paint into their own backing, and instead paint into this backing.
 bool CompositedLayerMapping::hasVisibleNonCompositingDescendantLayers() const
 {
     return hasVisibleNonCompositingDescendant(m_owningLayer);
 }
 
-bool CompositedLayerMapping::containsPaintedContent(bool isSimpleContainer) const
+bool CompositedLayerMapping::containsPaintedContent() const

[alokp, 2014/02/28 06:50:28]

We already have too many functions with similar names. I think it will be less
confusing if the code in isSimpleContainerCompositingLayer is moved into this
function.

Re-arranging the order in which the tests are done would also help performance.
If paintsIntoOwningLayer is expensive then you should not be calling that first.
You should first try trivial checks. Is there any problem with combining the two
functions?

[dshwang, 2014/02/28 10:59:53]

That's excellent idea.
I guess no. let me test.

 {
-    if (isSimpleContainer || paintsIntoCompositedAncestor() || m_artificiallyInflatedBounds || m_owningLayer->isReflection())
+    if (!hasVisibleContentOrNonCompositingDescendantLayers() || paintsIntoCompositedAncestor() || 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 (renderer()->isVideo() && toRenderVideo(renderer())->shouldDisplayVideo())
         return m_owningLayer->hasBoxDecorationsOrBackground();
 
@@ skipping 46 matching lines @@
     Image* image = cachedImage->imageForRenderer(imageRenderer);
     if (!image)
         return;
 
     // We have to wait until the image is fully loaded before setting it on the layer.
     if (!cachedImage->isLoaded())
         return;
 
     // This is a no-op if the layer doesn't have an inner layer for the image.
     m_graphicsLayer->setContentsToImage(image);
-    bool isSimpleContainer = false;
-    updateDrawsContent(isSimpleContainer);
+    updateDrawsContent();
 
     // Image animation is "lazy", in that it automatically stops unless someone is drawing
     // the image. So we have to kick the animation each time; this has the downside that the
     // image will keep animating, even if its layer is not visible.
     image->startAnimation();
 }
 
 FloatPoint3D CompositedLayerMapping::computeTransformOrigin(const IntRect& borderBox) const
 {
     RenderStyle* style = renderer()->style();
@@ skipping 26 matching lines @@
     return LayoutSize(-m_compositedBounds.x(), -m_compositedBounds.y());
 }
 
 LayoutRect CompositedLayerMapping::contentsBox() const
 {
     LayoutRect contentsBox = contentsRect(renderer());
     contentsBox.move(contentOffsetInCompostingLayer());
     return contentsBox;
 }
 
-IntRect CompositedLayerMapping::backgroundBox() const
-{
-    LayoutRect backgroundBox = backgroundRect(renderer());
-    backgroundBox.move(contentOffsetInCompostingLayer());
-    return pixelSnappedIntRect(backgroundBox);
-}
-
 GraphicsLayer* CompositedLayerMapping::parentForSublayers() const
 {
     if (m_scrollingContentsLayer)
         return m_scrollingContentsLayer.get();
 
     if (m_childContainmentLayer)
         return m_childContainmentLayer.get();
 
     if (m_childTransformLayer)
         return m_childTransformLayer.get();
@@ skipping 398 matching lines @@
     } else if (graphicsLayer == m_scrollingContentsLayer.get()) {
         name = "Scrolling Contents Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace WebCore