Reduce compositing update in Silk's toggle_drawer by 20%

Source/core/rendering/compositing/GraphicsLayerUpdater.cpp

 /*
  * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2014 Google 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
@@ skipping 30 matching lines @@
     : m_renderView(renderView)
     , m_pixelsWithoutPromotingAllTransitions(0.0)
     , m_pixelsAddedByPromotingAllTransitions(0.0)
 {
 }
 
 GraphicsLayerUpdater::~GraphicsLayerUpdater()
 {
 }
 
-void GraphicsLayerUpdater::rebuildTree(RenderLayer& layer, Vector<GraphicsLayer*>& childLayersOfEnclosingLayer, int depth)
+void GraphicsLayerUpdater::rebuildTree(RenderLayer& layer, UpdateType updateType, Vector<GraphicsLayer*>& childLayersOfEnclosingLayer, int depth)
 {
     // Make the layer compositing if necessary, and set up clipping and content layers.
     // Note that we can only do work here that is independent of whether the descendant layers
     // have been processed. computeCompositingRequirements() will already have done the repaint if necessary.
 
     layer.stackingNode()->updateLayerListsIfNeeded();
     layer.update3dRenderingContext();
 
     const bool hasCompositedLayerMapping = layer.hasCompositedLayerMapping();
     CompositedLayerMappingPtr currentCompositedLayerMapping = layer.compositedLayerMapping();
 
-    update(layer);
+    updateType = update(layer, updateType);
 
     // Grab some stats for histograms.
     if (hasCompositedLayerMapping) {
         m_pixelsWithoutPromotingAllTransitions += layer.size().height() * layer.size().width();
     } else {
         if ((layer.renderer()->style()->transitionForProperty(CSSPropertyOpacity) ||
              layer.renderer()->style()->transitionForProperty(CSSPropertyWebkitTransform)) &&
             m_renderView.viewRect().intersects(layer.absoluteBoundingBox()))
             m_pixelsAddedByPromotingAllTransitions += layer.size().height() * layer.size().width();
     }
 
     // If this layer has a compositedLayerMapping, then that is where we place subsequent children GraphicsLayers.
     // Otherwise children continue to append to the child list of the enclosing layer.
     Vector<GraphicsLayer*> layerChildren;
     Vector<GraphicsLayer*>& childList = hasCompositedLayerMapping ? layerChildren : childLayersOfEnclosingLayer;
 
 #if !ASSERT_DISABLED
     LayerListMutationDetector mutationChecker(layer.stackingNode());
 #endif
 
     if (layer.stackingNode()->isStackingContainer()) {
         RenderLayerStackingNodeIterator iterator(*layer.stackingNode(), NegativeZOrderChildren);
         while (RenderLayerStackingNode* curNode = iterator.next())
-            rebuildTree(*curNode->layer(), childList, depth + 1);
+            rebuildTree(*curNode->layer(), updateType, childList, depth + 1);
 
         // If a negative z-order child is compositing, we get a foreground layer which needs to get parented.
         if (hasCompositedLayerMapping && currentCompositedLayerMapping->foregroundLayer())
             childList.append(currentCompositedLayerMapping->foregroundLayer());
     }
 
     RenderLayerStackingNodeIterator iterator(*layer.stackingNode(), NormalFlowChildren | PositiveZOrderChildren);
     while (RenderLayerStackingNode* curNode = iterator.next())
-        rebuildTree(*curNode->layer(), childList, depth + 1);
+        rebuildTree(*curNode->layer(), updateType, childList, depth + 1);
 
     if (hasCompositedLayerMapping) {
         bool parented = false;
         if (layer.renderer()->isRenderPart())
             parented = RenderLayerCompositor::parentFrameContentLayers(toRenderPart(layer.renderer()));
 
         if (!parented)
             currentCompositedLayerMapping->parentForSublayers()->setChildren(layerChildren);
 
         // If the layer has a clipping layer the overflow controls layers will be siblings of the clipping layer.
@@ skipping 18 matching lines @@
         childLayersOfEnclosingLayer.append(currentCompositedLayerMapping->childForSuperlayers());
     }
 
     if (!depth) {
         int percentageIncreaseInPixels = static_cast<int>(m_pixelsAddedByPromotingAllTransitions / m_pixelsWithoutPromotingAllTransitions * 100);
         blink::Platform::current()->histogramCustomCounts("Renderer.PixelIncreaseFromTransitions", percentageIncreaseInPixels, 0, 1000, 50);
     }
 }
 
 // This just updates layer geometry without changing the hierarchy.
-void GraphicsLayerUpdater::updateRecursive(RenderLayer& layer)
+void GraphicsLayerUpdater::updateRecursive(RenderLayer& layer, UpdateType updateType)
 {
-    update(layer);
+    updateType = update(layer, updateType);
 
 #if !ASSERT_DISABLED
     LayerListMutationDetector mutationChecker(layer.stackingNode());
 #endif
 
     RenderLayerStackingNodeIterator iterator(*layer.stackingNode(), AllChildren);
     while (RenderLayerStackingNode* curNode = iterator.next())
-        updateRecursive(*curNode->layer());
+        updateRecursive(*curNode->layer(), updateType);
 }
 
-void GraphicsLayerUpdater::update(RenderLayer& layer)
+GraphicsLayerUpdater::UpdateType GraphicsLayerUpdater::update(RenderLayer& layer, UpdateType updateType)
 {
     if (!layer.hasCompositedLayerMapping())
-        return;
+        return updateType;
 
     CompositedLayerMappingPtr mapping = layer.compositedLayerMapping();
 
     // Note carefully: here we assume that the compositing state of all descendants have been updated already,
     // so it is legitimate to compute and cache the composited bounds for this layer.
     mapping->updateCompositedBounds();
 
     if (RenderLayerReflectionInfo* reflection = layer.reflectionInfo()) {
         if (reflection->reflectionLayer()->hasCompositedLayerMapping())
             reflection->reflectionLayer()->compositedLayerMapping()->updateCompositedBounds();
     }
 
     mapping->updateGraphicsLayerConfiguration();
-    mapping->updateGraphicsLayerGeometry();
+    updateType = mapping->updateGraphicsLayerGeometry(updateType);
+    mapping->willUpdateGeometryOfAllDecendants();

[esprehn, 2014/03/02 08:06:38]

It seems like willUpdateGeometryOfAllDecendants() should be inside
updateRecursive, otherwise you can call update() and it'll clear the child bit
but not really do the recursive work?

[abarth-chromium, 2014/03/02 08:22:36]

That's why I moved this code into a separate GraphicsLayerUpdater class.  The
|update| function is now private and is only called by two functions, both of
which will complete the recursive walk.

 
     if (!layer.parent())
         layer.compositor()->updateRootLayerPosition();
 
     if (mapping->hasUnpositionedOverflowControlsLayers())
         layer.scrollableArea()->positionOverflowControls();
+
+    return updateType;
 }
 
 } // namespace WebCore