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

Source/core/platform/graphics/GraphicsLayer.cpp

Index: Source/core/platform/graphics/GraphicsLayer.cpp
diff --git a/Source/core/platform/graphics/GraphicsLayer.cpp b/Source/core/platform/graphics/GraphicsLayer.cpp
index 6b6505187d94cf264d69571656488d616460a3b2..47d1cbce643dd680ca97368383990c78730cb83a 100644
--- a/Source/core/platform/graphics/GraphicsLayer.cpp
+++ b/Source/core/platform/graphics/GraphicsLayer.cpp
@@ -109,6 +109,8 @@ GraphicsLayer::GraphicsLayer(GraphicsLayerClient* client)
     , m_anchorPoint(0.5f, 0.5f, 0)
     , m_opacity(1)
     , m_zPosition(0)
+    , m_blendMode(BlendModeNormal)
+    , m_isRootForIsolatedGroup(false)
     , m_contentsOpaque(false)
     , m_preserves3D(false)
     , m_backfaceVisibility(true)
@@ -729,6 +731,16 @@ void GraphicsLayer::dumpProperties(TextStream& ts, int indent, LayerTreeFlags fl
         ts << "(opacity " << m_opacity << ")\n";
     }
 
+    if (m_blendMode != BlendModeNormal) {
+        writeIndent(ts, indent + 1);
+        ts << "(blendMode " << m_blendMode << ")\n";

[shawnsingh, 2013/09/13 10:22:59]

Does this mean that various blend modes will be identified as integers in the
output of layout tests?  I think we should stringify this somehow, so that there
is some sanity to looking at the output manually.  Could be a major timesaver
for anyone who needs to debug blend mode layout tests in the future.

[rosca, 2013/09/19 14:26:54]

Done.

+    }
+
+    if (m_isRootForIsolatedGroup) {
+        writeIndent(ts, indent + 1);
+        ts << "(isolate " << m_isRootForIsolatedGroup << ")\n";
+    }
+
     if (m_contentsOpaque) {
         writeIndent(ts, indent + 1);
         ts << "(contentsOpaque " << m_contentsOpaque << ")\n";
@@ -1016,6 +1028,22 @@ void GraphicsLayer::setOpacity(float opacity)
     platformLayer()->setOpacity(opacity);
 }
 
+void GraphicsLayer::setBlendMode(BlendMode blendMode)
+{
+    if (m_blendMode == blendMode)
+        return;
+    m_blendMode = blendMode;
+    platformLayer()->setBlendMode(WebKit::WebBlendMode(blendMode));

[shawnsingh, 2013/09/13 10:22:59]

using platformLayer() here seems correct.  I just want to make sure that we
consider the case where GraphicsLayer has a contentsLayer in addition to
m_layer, and which of those layers would we want to set the blend mode.

[rosca, 2013/09/19 14:26:54]

We set the blend mode to the outermost layer so it can take its subtree and
blend it with the backdrop. contentsLayer is set as a child of the
platformLayer, so it is fine to set the blend mode to the platformLayer. I 
tried to blend elements with contensLayer (accelerated canvas) and it seems to
work.

+}
+
+void GraphicsLayer::setIsRootForIsolatedGroup(bool isolated)
+{
+    if (m_isRootForIsolatedGroup == isolated)
+        return;
+    m_isRootForIsolatedGroup = isolated;
+    platformLayer()->setIsRootForIsolatedGroup(isolated);

[shawnsingh, 2013/09/13 10:22:59]

Same issue for platformLayer() accessor here.

[rosca, 2013/09/19 14:26:54]

Done.

+}
+
 void GraphicsLayer::setContentsNeedsDisplay()
 {
     if (WebLayer* contentsLayer = contentsLayerIfRegistered()) {