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

Source/core/rendering/CompositedLayerMapping.cpp

Index: Source/core/rendering/CompositedLayerMapping.cpp
diff --git a/Source/core/rendering/CompositedLayerMapping.cpp b/Source/core/rendering/CompositedLayerMapping.cpp
index e1e41cd4f92137e54b6eb5ffaf030b81b69590bd..21343769146fcc623a4b89492e1772c9a100271a 100644
--- a/Source/core/rendering/CompositedLayerMapping.cpp
+++ b/Source/core/rendering/CompositedLayerMapping.cpp
@@ -217,6 +217,8 @@ void CompositedLayerMapping::createPrimaryGraphicsLayer()
 
     if (RuntimeEnabledFeatures::cssCompositingEnabled())
         updateLayerBlendMode(renderer()->style());
+    if (RuntimeEnabledFeatures::cssCompositingEnabled())

[enne (OOO), 2013/11/07 22:59:07]

Put these under the same conditional.

[rosca, 2013/11/08 15:36:32]

Done.

+        updateIsRootForIsolatedGroup();
 }
 
 void CompositedLayerMapping::destroyGraphicsLayers()
@@ -273,8 +275,15 @@ void CompositedLayerMapping::updateFilters(const RenderStyle* style)
     }
 }
 
-void CompositedLayerMapping::updateLayerBlendMode(const RenderStyle*)
+void CompositedLayerMapping::updateLayerBlendMode(const RenderStyle* style)
+{
+    setBlendMode(style->blendMode());
+}
+
+void CompositedLayerMapping::updateIsRootForIsolatedGroup()
 {
+    m_graphicsLayer->setIsRootForIsolatedGroup(m_owningLayer->hasCompositedBlendingDescendants()

[enne (OOO), 2013/11/07 22:59:07]

Whoa there.  If you have a tree of RenderLayers creating stacking contexts with
a blending child at the bottom, then all of them will be set as roots for
isolated groups and needlessly become composited layers?  And therefore also in
Chromium all of them will needlessly become render surfaces?

[rosca, 2013/11/08 15:36:32]

No. hasCompositedBlendingDescendants is true only if the layer has a descendant
in the current stacking context, descendants that are enclosed in a descendant
stacking contexts are not taken into account.
I agree that the function name doesn't suggest the same thing. I renamed it to
requiresIsolationForCompositedStackingContext. It will be set to true for all
the layers nodes between the blending layer up to its stacking context layer.
Only the stacking contexts having this flag set will request an isolated group.

+        && m_owningLayer->stackingNode()->isStackingContext());
 }
 
 void CompositedLayerMapping::updateContentsOpaque()
@@ -521,6 +530,8 @@ void CompositedLayerMapping::updateGraphicsLayerGeometry()
 
     if (RuntimeEnabledFeatures::cssCompositingEnabled())
         updateLayerBlendMode(renderer()->style());
+    if (RuntimeEnabledFeatures::cssCompositingEnabled())
+        updateIsRootForIsolatedGroup();
 
     bool isSimpleContainer = isSimpleContainerCompositingLayer();
 
@@ -1552,8 +1563,15 @@ void CompositedLayerMapping::setRequiresOwnBackingStore(bool requiresOwnBacking)
     compositor()->repaintInCompositedAncestor(m_owningLayer, compositedBounds());
 }
 
-void CompositedLayerMapping::setBlendMode(BlendMode)
+void CompositedLayerMapping::setBlendMode(BlendMode blendMode)
 {
+    if (m_ancestorClippingLayer) {
+        ASSERT(childForSuperlayers() == m_ancestorClippingLayer.get());
+        m_graphicsLayer->setBlendMode(BlendModeNormal);
+    } else {
+        ASSERT(childForSuperlayers() == m_graphicsLayer.get());
+    }
+    childForSuperlayers()->setBlendMode(blendMode);
 }
 
 void CompositedLayerMapping::setContentsNeedDisplay()