Enable fast/images with slimming paint

Source/core/paint/TransparencyDisplayItem.cpp

Index: Source/core/paint/TransparencyDisplayItem.cpp
diff --git a/Source/core/paint/TransparencyDisplayItem.cpp b/Source/core/paint/TransparencyDisplayItem.cpp
index 77605749f74b035fee3a09e5c0dd1def7c8bb693..bae051acd5de09e6926b37b365916cb705bb5b27 100644
--- a/Source/core/paint/TransparencyDisplayItem.cpp
+++ b/Source/core/paint/TransparencyDisplayItem.cpp
@@ -5,14 +5,19 @@
 #include "config.h"
 #include "core/paint/TransparencyDisplayItem.h"
 
+#include "core/rendering/RenderObject.h"
+#include "core/rendering/RenderView.h"
+#include "platform/RuntimeEnabledFeatures.h"
 #include "platform/graphics/GraphicsContext.h"
 
 namespace blink {
 
 void BeginTransparencyDisplayItem::replay(GraphicsContext* context)
 {
-    context->save();
-    context->clip(m_clipRect);
+    if (m_clipBehavior == ClipToRect) {

[chrishtr, 2014/11/21 20:09:02]

Should we just create an extra ClipDisplayItem rather than having this code
here?

+        context->save();
+        context->clip(m_clipRect);
+    }
 
     bool hasBlendMode = this->hasBlendMode();
     if (hasBlendMode)
@@ -40,7 +45,8 @@ WTF::String BeginTransparencyDisplayItem::asDebugString() const
 void EndTransparencyDisplayItem::replay(GraphicsContext* context)
 {
     context->endLayer();
-    context->restore();
+    if (m_clipBehavior == ClipToRect)
+        context->restore();
 }
 
 #ifndef NDEBUG
@@ -51,4 +57,26 @@ WTF::String EndTransparencyDisplayItem::asDebugString() const
 }
 #endif
 
+TransparencyRecorder::TransparencyRecorder(GraphicsContext* graphicsContext, const RenderObject* renderer, DisplayItem::Type type, const LayoutRect& clipRect, const WebBlendMode& blendMode, const float opacity, TransparencyClipBehavior clipBehavior)
+    : m_renderer(renderer)
+    , m_type(type)
+    , m_graphicsContext(graphicsContext)
+    , m_clipBehavior(clipBehavior)
+{
+    OwnPtr<BeginTransparencyDisplayItem> beginTransparencyDisplayItem = adoptPtr(new BeginTransparencyDisplayItem(renderer, type, clipRect, blendMode, opacity, clipBehavior));
+    if (RuntimeEnabledFeatures::slimmingPaintEnabled())
+        renderer->view()->viewDisplayList().add(beginTransparencyDisplayItem.release());
+    else
+        beginTransparencyDisplayItem->replay(graphicsContext);
+}
+
+TransparencyRecorder::~TransparencyRecorder()
+{
+    OwnPtr<EndTransparencyDisplayItem> endTransparencyDisplayItem = adoptPtr(new EndTransparencyDisplayItem(m_renderer, m_type, m_clipBehavior));
+    if (RuntimeEnabledFeatures::slimmingPaintEnabled())
+        m_renderer->view()->viewDisplayList().add(endTransparencyDisplayItem.release());
+    else
+        endTransparencyDisplayItem->replay(m_graphicsContext);
+}
+
 } // namespace blink