Store repaint rects in the coordinate space of their backing GraphicsLayer.

Source/core/rendering/RenderObject.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 789 matching lines @@
 
     // Return the RenderLayerModelObject in the container chain which is responsible for painting this object, or 0
     // if painting is root-relative. This is the container that should be passed to the 'forRepaint'
     // methods.
     const RenderLayerModelObject* containerForRepaint() const;
     const RenderLayerModelObject* enclosingCompositedContainer() const;
     const RenderLayerModelObject* adjustCompositedContainerForSpecialAncestors(const RenderLayerModelObject* repaintContainer) const;
     bool isRepaintContainer() const;
 
     // Returns the repaint rect for this RenderObject in the coordinate space of the composited layer that this RenderObject paints into, or the RenderView if not
-    // composited.
-    LayoutRect computeRepaintRect() const;
+    // composited. If |repaintContainer| is 0, uses containerForRepaint().
+    LayoutRect computeRepaintRect(const RenderLayerModelObject* repaintContainer = 0) const;

[leviw_travelin_and_unemployed, 2014/05/29 18:27:08]

How about a computeRepaintRect that takes no parameters that's inline and calls
the one that takes a parameter with containerForRepaint? I only suggest this
because we want to be very clear that you should never be in this code without a
repaint container.

[chrishtr, 2014/05/29 18:34:11]

Never be in this code without a repaint container? What do you mean?

+
+    // Returns the rect bounds needed to repaint this object, in the coordinate space of the rendering backing of |repaintContainer|
+    LayoutRect boundsRectForRepaint(const RenderLayerModelObject* repaintContainer) const;
 
     // Actually do the repaint of rect r for this object which has been computed in the coordinate space
     // of repaintContainer. If repaintContainer is 0, repaint via the view.
     void repaintUsingContainer(const RenderLayerModelObject* repaintContainer, const IntRect&, InvalidationReason) const;
 
     // Repaint the entire object.  Called when, e.g., the color of a border changes, or when a border
     // style changes.
     void repaint() const;
 
     // Repaint a specific subrectangle within a given object.  The rect |r| is in the object's coordinate space.
@@ skipping 248 matching lines @@
     // containerRect is a rect that has already been added for the currentLayer which is likely to
     // be a container for child elements. Any rect wholly contained by containerRect can be
     // skipped.
     virtual void addLayerHitTestRects(LayerHitTestRects&, const RenderLayer* currentLayer, const LayoutPoint& layerOffset, const LayoutRect& containerRect) const;
 
     // Add hit-test rects for this renderer only to the provided list. layerOffset is the offset
     // of this renderer within the current layer that should be used for each result.
     virtual void computeSelfHitTestRects(Vector<LayoutRect>&, const LayoutPoint& layerOffset) const { };
 
 private:
-    LayoutRect computeRepaintRectInternal(const RenderLayerModelObject* repaintContainer) const;
-
     RenderBlock* containerForFixedPosition(const RenderLayerModelObject* repaintContainer = 0, bool* repaintContainerSkipped = 0) const;
 
     RenderFlowThread* locateFlowThreadContainingBlock() const;
     void removeFromRenderFlowThread();
     void removeFromRenderFlowThreadRecursive(RenderFlowThread*);
 
     bool hasImmediateNonWhitespaceTextChildOrPropertiesDependentOnColor() const;
 
     RenderStyle* cachedFirstLineStyle() const;
     StyleDifference adjustStyleDifference(StyleDifference, unsigned contextSensitiveProperties) const;
@@ skipping 392 matching lines @@
 void showTree(const WebCore::RenderObject*);
 void showLineTree(const WebCore::RenderObject*);
 void showRenderTree(const WebCore::RenderObject* object1);
 // We don't make object2 an optional parameter so that showRenderTree
 // can be called from gdb easily.
 void showRenderTree(const WebCore::RenderObject* object1, const WebCore::RenderObject* object2);
 
 #endif
 
 #endif // RenderObject_h