Compute better reference/visual boxes for clip-path in columns

third_party/WebKit/Source/core/paint/PaintLayer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. 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>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 2058 matching lines @@
     return toLayoutBox(layoutObject())->borderBoxRect();
 }
 
 bool PaintLayer::hitTestClippedOutByClipPath(PaintLayer* rootLayer, const HitTestLocation& hitTestLocation) const
 {
     if (!layoutObject()->hasClipPath())
         return false;
     DCHECK(isSelfPaintingLayer());
     DCHECK(rootLayer);
 
-    LayoutPoint offsetToRootLayer;
-    convertToLayerCoords(rootLayer, offsetToRootLayer);
     LayoutRect referenceBox(boxForClipPath());
-    referenceBox.moveBy(offsetToRootLayer);
+    if (enclosingPaginationLayer())
+        convertFromFlowThreadToVisualBoundingBoxInAncestor(rootLayer, referenceBox);
+    else
+        convertToLayerCoords(rootLayer, referenceBox);
 
     FloatPoint point(hitTestLocation.point());
 
     ClipPathOperation* clipPathOperation = layoutObject()->style()->clipPath();
     DCHECK(clipPathOperation);
     if (clipPathOperation->type() == ClipPathOperation::SHAPE) {
         ShapeClipPathOperation* clipPath = toShapeClipPathOperation(clipPathOperation);
         return !clipPath->path(FloatRect(referenceBox)).contains(point);
     }
     DCHECK_EQ(clipPathOperation->type(), ClipPathOperation::REFERENCE);
     ReferenceClipPathOperation* referenceClipPathOperation = toReferenceClipPathOperation(clipPathOperation);
     Element* element = layoutObject()->document().getElementById(referenceClipPathOperation->fragment());
     if (!isSVGClipPathElement(element) || !element->layoutObject())
         return false;
     LayoutSVGResourceClipper* clipper =
         toLayoutSVGResourceClipper(toLayoutSVGResourceContainer(element->layoutObject()));
     // If the clipPath is using "userspace on use" units, then the origin of
     // the coordinate system is the top-left of the reference box, so adjust
     // the point accordingly.
     if (clipper->clipPathUnits() == SVGUnitTypes::kSvgUnitTypeUserspaceonuse)
-        point.moveBy(-offsetToRootLayer);
+        point.moveBy(-referenceBox.location());
     return !clipper->hitTestClipContent(FloatRect(referenceBox), point);
 }
 
 bool PaintLayer::intersectsDamageRect(const LayoutRect& layerBounds, const LayoutRect& damageRect, const LayoutPoint& offsetFromRoot) const
 {
     // Always examine the canvas and the root.
     // FIXME: Could eliminate the isDocumentElement() check if we fix background painting so that the LayoutView
     // paints the root's background.
     if (isRootLayer() || layoutObject()->isDocumentElement())
         return true;
@@ skipping 837 matching lines @@
 
 void showLayerTree(const blink::LayoutObject* layoutObject)
 {
     if (!layoutObject) {
         fprintf(stderr, "Cannot showLayerTree. Root is (nil)\n");
         return;
     }
     showLayerTree(layoutObject->enclosingLayer());
 }
 #endif