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

Source/core/platform/graphics/GraphicsLayer.cpp

 /*
  * Copyright (C) 2009 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 91 matching lines @@
 PassOwnPtr<GraphicsLayer> GraphicsLayer::create(GraphicsLayerFactory* factory, GraphicsLayerClient* client)
 {
     return factory->createGraphicsLayer(client);
 }
 
 GraphicsLayer::GraphicsLayer(GraphicsLayerClient* client)
     : m_client(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)
     , m_masksToBounds(false)
     , m_drawsContent(false)
     , m_contentsVisible(true)
     , m_paintingPhase(GraphicsLayerPaintAllWithOverflowClip)
     , m_contentsOrientation(CompositingCoordinatesTopDown)
     , m_parent(0)
     , m_maskLayer(0)
@@ skipping 600 matching lines @@
     if (m_size != IntSize()) {
         writeIndent(ts, indent + 1);
         ts << "(bounds " << m_size.width() << " " << m_size.height() << ")\n";
     }
 
     if (m_opacity != 1) {
         writeIndent(ts, indent + 1);
         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";
     }
 
     if (m_preserves3D) {
         writeIndent(ts, indent + 1);
         ts << "(preserves3D " << m_preserves3D << ")\n";
     }
 
@@ skipping 267 matching lines @@
     m_layer->setDoubleSided(m_backfaceVisibility);
 }
 
 void GraphicsLayer::setOpacity(float opacity)
 {
     float clampedOpacity = std::max(std::min(opacity, 1.0f), 0.0f);
     m_opacity = clampedOpacity;
     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()) {
         contentsLayer->invalidate();
         addRepaintRect(contentsRect());
     }
 }
 
 void GraphicsLayer::setNeedsDisplay()
 {
@@ skipping 301 matching lines @@
 #ifndef NDEBUG
 void showGraphicsLayerTree(const WebCore::GraphicsLayer* layer)
 {
     if (!layer)
         return;
 
     String output = layer->layerTreeAsText(WebCore::LayerTreeIncludesDebugInfo);
     fprintf(stderr, "%s\n", output.utf8().data());
 }
 #endif