Generalize paint chunks to clips, and implement clips in LayerPainter.

Source/core/paint/ViewDisplayList.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ViewDisplayList_h
 #define ViewDisplayList_h
 
 #include "core/rendering/PaintPhase.h"
+#include "platform/geometry/RoundedRect.h"
 #include "platform/graphics/DisplayList.h"
 #include "wtf/HashSet.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 class GraphicsContext;
 class RenderObject;
+class RenderLayer;
 struct AtomicPaintChunk;
 
-typedef Vector<OwnPtr<AtomicPaintChunk> > PaintCommandList;
 
-struct AtomicPaintChunk {
+struct DisplayItem {
+    virtual void replay(GraphicsContext*) = 0;
+
+    virtual ~DisplayItem() { }
+};
+
+struct ClipDisplayItem : DisplayItem {
+    RenderLayer* layer;
+    enum ClipType {
+        LayerOverflowControls,
+        LayerBackground,
+        LayerParent,
+        LayerFilter,
+        LayerForeground,
+        LayerFragmentFloat,
+        LayerFragmentForeground,
+        LayerFragmentChildOutline,
+        LayerFragmentOutline,
+        LayerFragmentMask,
+        LayerFragmentClippingMask,
+        LayerFragmentParent
+    };
+    ClipType clipType;
+    IntRect clipRect;
+    Vector<RoundedRect> roundedRectClips;
+
+    virtual void replay(GraphicsContext*);
+};
+
+struct EndClipDisplayItem : DisplayItem {
+    RenderLayer* layer;
+    virtual void replay(GraphicsContext*);
+};
+
+struct AtomicPaintChunk : DisplayItem {
     AtomicPaintChunk(PassRefPtr<DisplayList> inDisplayList, RenderObject* inRenderer, PaintPhase inPhase)
         : displayList(inDisplayList), renderer(inRenderer), phase(inPhase) { };
 
     RefPtr<DisplayList> displayList;
 
     // This auxillary data can be moved off the chunk if needed.
     RenderObject* renderer;
     PaintPhase phase;
+
+    virtual void replay(GraphicsContext*);
 };
 
+typedef Vector<OwnPtr<DisplayItem> > PaintList;
+
 class PaintCommandRecorder {
 public:
     explicit PaintCommandRecorder(GraphicsContext*, RenderObject*, PaintPhase, const FloatRect&);
     ~PaintCommandRecorder();
 
 private:
     GraphicsContext* m_context;
     RenderObject* m_renderer;
     PaintPhase m_phase;
 };
 
+class PaintClipRecorder {
+public:
+    explicit PaintClipRecorder(RenderLayer*, ClipDisplayItem::ClipType);
+    void setClipRect(IntRect);
+    void addRoundedRectClip(const RoundedRect&);
+    void startClip();
+    void endClip();
+
+private:
+    OwnPtr<ClipDisplayItem> clipDisplayItem;
+#ifdef ASSERT_ENABLED
+    bool m_started, m_ended;
+#endif
+};
+
 class ViewDisplayList {
 public:
     ViewDisplayList() { };
 
-    const PaintCommandList& paintCommandList();
-    void add(WTF::PassOwnPtr<AtomicPaintChunk>);
+    const PaintList& paintList();
+    void add(WTF::PassOwnPtr<DisplayItem>);
     void invalidate(const RenderObject*);
 
 private:
-    bool isRepaint(PaintCommandList::iterator, const AtomicPaintChunk&);
+    bool isRepaint(PaintList::iterator, const DisplayItem&);
     // Update m_paintList with any invalidations or new paints.
-    void updatePaintCommandList();
+    void updatePaintList();
 
-    PaintCommandList m_paintList;
+    PaintList m_paintList;
     HashSet<const RenderObject*> m_invalidated;
-    PaintCommandList m_newPaints;
+    PaintList m_newPaints;
 };
 
 } // namespace blink
 
 #endif // ViewDisplayList_h