mix-blend-mode implementation for accelerated layers - blink part

Source/core/rendering/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 193 matching lines @@
 
 #if !OS(ANDROID)
     if (m_isMainFrameRenderViewLayer)
         m_graphicsLayer->contentLayer()->setDrawCheckerboardForMissingTiles(true);
 #endif
 
     updateOpacity(renderer()->style());
     updateTransform(renderer()->style());
     updateFilters(renderer()->style());
 
-    if (RuntimeEnabledFeatures::cssCompositingEnabled())
+    if (RuntimeEnabledFeatures::cssCompositingEnabled()) {
         updateLayerBlendMode(renderer()->style());
+        updateIsRootForIsolatedGroup();
+    }
 }
 
 void CompositedLayerMapping::destroyGraphicsLayers()
 {
     if (m_graphicsLayer)
         m_graphicsLayer->removeFromParent();
 
     m_ancestorClippingLayer = nullptr;
     m_graphicsLayer = nullptr;
     m_foregroundLayer = nullptr;
@@ skipping 36 matching lines @@
         //
         // Similarly, if filters used to be painted in the compositor and are now painted in software, we need to:
         // (1) Create a FilterEffectRenderer.
         // (2) Repaint the layer contents to apply a software filter because the compositor won't apply it.
         //
         m_owningLayer->updateOrRemoveFilterEffectRenderer();
         setContentsNeedDisplay();
     }
 }
 
-void CompositedLayerMapping::updateLayerBlendMode(const RenderStyle*)
+void CompositedLayerMapping::updateLayerBlendMode(const RenderStyle* style)
 {
+    setBlendMode(style->blendMode());
+}
+
+void CompositedLayerMapping::updateIsRootForIsolatedGroup()
+{
+    bool isolate = m_owningLayer->shouldIsolateCompositedDescendants();
+
+    // non stacking context layers should never isolate
+    ASSERT(m_owningLayer->stackingNode()->isStackingContext() || !isolate);
+
+    m_graphicsLayer->setIsRootForIsolatedGroup(isolate);
 }
 
 void CompositedLayerMapping::updateContentsOpaque()
 {
     // For non-root layers, background is always painted by the primary graphics layer.
     ASSERT(m_isMainFrameRenderViewLayer || !m_backgroundLayer);
     if (m_backgroundLayer) {
         m_graphicsLayer->setContentsOpaque(false);
         m_backgroundLayer->setContentsOpaque(m_owningLayer->backgroundIsKnownToBeOpaqueInRect(compositedBounds()));
     } else {
@@ skipping 231 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 (!renderer()->animation().isRunningAcceleratedAnimationOnRenderer(renderer(), CSSPropertyWebkitTransform))
         updateTransform(renderer()->style());
 
     // Set opacity, if it is not animating.
     if (!renderer()->animation().isRunningAcceleratedAnimationOnRenderer(renderer(), CSSPropertyOpacity))
         updateOpacity(renderer()->style());
 
-    if (RuntimeEnabledFeatures::cssCompositingEnabled())
+    if (RuntimeEnabledFeatures::cssCompositingEnabled()) {

[shawnsingh, 2013/11/23 00:38:13]

I think it would be equivalent to move these down to the end of this function
along with all the other updateXXX functions, right?  If that's true, let's do
it that way.

[rosca, 2013/11/25 21:11:41]

It should be the same. Done.

         updateLayerBlendMode(renderer()->style());
+        updateIsRootForIsolatedGroup();
+    }
 
     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()) {
@@ skipping 1042 matching lines @@
 void CompositedLayerMapping::paintsIntoCompositedAncestorChanged()
 {
     // The answer to paintsIntoCompositedAncestor() affects cached clip rects, so when
     // it changes we have to clear clip rects on descendants.
     m_owningLayer->clipper().clearClipRectsIncludingDescendants(PaintingClipRects);
     m_owningLayer->repainter().computeRepaintRectsIncludingDescendants();
 
     compositor()->repaintInCompositedAncestor(m_owningLayer, compositedBounds());
 }
 
-void CompositedLayerMapping::setBlendMode(BlendMode)
+void CompositedLayerMapping::setBlendMode(BlendMode blendMode)
 {
+    if (m_ancestorClippingLayer) {

[shawnsingh, 2013/11/23 00:38:13]

lately we are adding more layers in the CompositedLayerMapping, each of which
may be the childForSuperlayers() under different scenarios.  So it's probably
best not to rely on childForSuperLayers() unless you intend to reset the blend
mode to BlendModeNormal for all these other layers, too.

Would it work to simply use m_graphicsLayer to house the blend mode always?  Why
does it need to be the root-most layer of this cluster?

[rosca, 2013/11/25 21:11:41]

The same approach is used by scrolling coordinator (updateScrollParent). We
should keep this in sync when other childForSuperlayers are added.
Blending doesn't work if the blend mode is set on m_graphicsLayer being clipped
by an ancestorClippingLayer. It seems like such a structure doesn't allow cc
renderer to copy the correct backdrop. I should look more into this. I'd prefer
to address this with a follow-up patch if you are ok with this.
Added a layout test with this scenario.

+        ASSERT(childForSuperlayers() == m_ancestorClippingLayer.get());
+        m_graphicsLayer->setBlendMode(BlendModeNormal);
+    } else {
+        ASSERT(childForSuperlayers() == m_graphicsLayer.get());
+    }
+    childForSuperlayers()->setBlendMode(blendMode);
 }
 
 void CompositedLayerMapping::setContentsNeedDisplay()
 {
     ASSERT(!paintsIntoCompositedAncestor());
 
     if (m_graphicsLayer && m_graphicsLayer->drawsContent())
         m_graphicsLayer->setNeedsDisplay();
 
     if (m_foregroundLayer && m_foregroundLayer->drawsContent())
@@ skipping 419 matching lines @@
     } else if (graphicsLayer == m_scrollingContentsLayer.get()) {
         name = "Scrolling Contents Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace WebCore