Subtree caching implementation in blink-core

Source/core/paint/DeprecatedPaintLayer.h

Index: Source/core/paint/DeprecatedPaintLayer.h
diff --git a/Source/core/paint/DeprecatedPaintLayer.h b/Source/core/paint/DeprecatedPaintLayer.h
index a82ca8e54b1c2b9a1d2b03b8c2d918b890d01b34..c79d1eccc38b72ec0166df69afc5a009f9359c8e 100644
--- a/Source/core/paint/DeprecatedPaintLayer.h
+++ b/Source/core/paint/DeprecatedPaintLayer.h
@@ -109,7 +109,9 @@ public:
     DeprecatedPaintLayer* firstChild() const { return m_first; }
     DeprecatedPaintLayer* lastChild() const { return m_last; }
 
-    const DeprecatedPaintLayer* compositingContainer() const;
+    // TODO(wangxianzhu): Find a better name for it. 'paintContainer' might be good but
+    // we can't use it for now because it conflicts with PaintInfo::paintContainer.

[chrishtr, 2015/08/27 04:29:48]

How about stackingContainerForPaint()? With a comment saying that it's either a
stacking context or acts like one in the context
of the css 2.1 painting algorithm?

[Xianzhu, 2015/08/27 16:38:02]

stackingContainerForPaint seems incomplete, because for a
non-treated-as-stacking-context layer, the function returns the parent layer of
any kind, including non-stacking-context overflow-scroll layer.

A description might be: the ancestor layer whose paintLayer method will directly
call this layer's paintLayer method.

+    DeprecatedPaintLayer* compositingContainer() const;
 
     void addChild(DeprecatedPaintLayer* newChild, DeprecatedPaintLayer* beforeChild = 0);
     DeprecatedPaintLayer* removeChild(DeprecatedPaintLayer*);
@@ -537,6 +539,10 @@ public:
     static LayoutRect transparencyClipBox(const DeprecatedPaintLayer*, const DeprecatedPaintLayer* rootLayer, TransparencyClipBoxBehavior transparencyBehavior,
         TransparencyClipBoxMode transparencyMode, GlobalPaintFlags = GlobalPaintNormalPhase);
 
+    bool needsRepaint() const { return m_needsRepaint; }
+    void setNeedsRepaint();
+    void clearNeedsRepaint() { m_needsRepaint = false; }
+
 private:
     // Bounding box in the coordinates of this layer.
     LayoutRect logicalBoundingBox() const;
@@ -609,6 +615,8 @@ private:
 
     void blockSelectionGapsBoundsChanged();
 
+    void markCompositingContainerChainForChildNeedsRepaint();
+
     DeprecatedPaintLayerType m_layerType;
 
     // Self-painting layer is an optimization where we avoid the heavy Layer painting
@@ -660,6 +668,8 @@ private:
     // and we don't yet know to what graphics layer this Layer will be assigned.
     unsigned m_lostGroupedMapping : 1;
 
+    unsigned m_needsRepaint : 1;
+
     LayoutBoxModelObject* m_layoutObject;
 
     DeprecatedPaintLayer* m_parent;