Use fragmented bounding box for hit-test/paint clipping.

Source/core/rendering/RenderLayer.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
@@ skipping 210 matching lines @@
     void convertToLayerCoords(const RenderLayer* ancestorLayer, LayoutRect&) const;
 
     // The hitTest() method looks for mouse events by walking layers that intersect the point from front to back.
     bool hitTest(const HitTestRequest&, HitTestResult&);
     bool hitTest(const HitTestRequest&, const HitTestLocation&, HitTestResult&);
 
     // Pass offsetFromRoot if known.
     bool intersectsDamageRect(const LayoutRect& layerBounds, const LayoutRect& damageRect, const RenderLayer* rootLayer, const LayoutPoint* offsetFromRoot = 0) const;
 
     // Bounding box relative to some ancestor layer. Pass offsetFromRoot if known.
-    LayoutRect physicalBoundingBox(const RenderLayer* ancestorLayer, const LayoutPoint* offsetFromRoot = 0) const;
-    LayoutRect physicalBoundingBoxIncludingReflectionAndStackingChildren(const RenderLayer* ancestorLayer, const LayoutPoint& offsetFromRoot) const;

[Julien - ping for review, 2014/10/03 21:38:49]

Those 2 renamings are basically undoing what 18e0c42d did. While I prefer the
name without the physical prefix, I don't think it warrants the history churn
that we are introducing.

[rune, 2014/10/06 07:09:46]

Done.

+    LayoutRect boundingBox(const RenderLayer* ancestorLayer, const LayoutPoint* offsetFromRoot = 0) const;
+    LayoutRect boundingBoxIncludingReflectionAndStackingChildren(const RenderLayer* ancestorLayer, const LayoutPoint& offsetFromRoot) const;
+    LayoutRect fragmentsBoundingBox(const RenderLayer* ancestorLayer) const;
 
     // FIXME: This function is inconsistent as to whether the returned rect has been flipped for writing mode.
     LayoutRect boundingBoxForCompositingOverlapTest() const { return overlapBoundsIncludeChildren() ? boundingBoxForCompositing() : logicalBoundingBox(); }
 
     // If true, this layer's children are included in its bounds for overlap testing.
     // We can't rely on the children's positions if this layer has a filter that could have moved the children's pixels around.
     bool overlapBoundsIncludeChildren() const { return hasFilter() && renderer()->style()->filter().hasFilterThatMovesPixels(); }
 
     enum CalculateBoundsOptions {
         ApplyBoundsChickenEggHacks,
@@ skipping 293 matching lines @@
         DescendantsOfTransparencyClipBox,
         RootOfTransparencyClipBox
     };
 
     static LayoutRect transparencyClipBox(const RenderLayer*, const RenderLayer* rootLayer, TransparencyClipBoxBehavior transparencyBehavior,
         TransparencyClipBoxMode transparencyMode, const LayoutSize& subPixelAccumulation, PaintBehavior = 0);
 
 private:
     // Bounding box in the coordinates of this layer.
     LayoutRect logicalBoundingBox() const;
+    LayoutRect flippedLogicalBoundingBox() const;
 
     bool hasOverflowControls() const;
 
     void setAncestorChainHasSelfPaintingLayerDescendant();
     void dirtyAncestorChainHasSelfPaintingLayerDescendantStatus();
 
     void updateLayerPositionRecursive();
 
     void setNextSibling(RenderLayer* next) { m_next = next; }
     void setPreviousSibling(RenderLayer* prev) { m_previous = prev; }
@@ skipping 158 matching lines @@
 
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showLayerTree(const blink::RenderLayer*);
 void showLayerTree(const blink::RenderObject*);
 #endif
 
 #endif // RenderLayer_h