Support edge-inclusive intersections in mapToVisibleRectInAncestorSpace

third_party/WebKit/Source/platform/geometry/LayoutRect.h

 /*
  * Copyright (c) 2012, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 146 matching lines @@
     // This checks to see if the rect contains x,y in the traditional sense.
     // Equivalent to checking if the rect contains a 1x1 rect below and to the right of (px,py).
     bool contains(LayoutUnit px, LayoutUnit py) const
         { return px >= x() && px < maxX() && py >= y() && py < maxY(); }
     bool contains(const LayoutPoint& point) const { return contains(point.x(), point.y()); }
 
     void intersect(const LayoutRect&);
     void unite(const LayoutRect&);
     void uniteIfNonZero(const LayoutRect&);
 
+    // Set this rect to be the intersection of itself and the argument rect
+    // using edge-inclusive geometry.  If the two rectangles overlap but the
+    // overlap region is zero-area (either because one of the two rectangles
+    // is zero-area, or because the rectangles overlap at an edge or a corner),
+    // the result is the zero-area intersection.  The return value indicates
+    // whether the two rectangle actually have an intersection, since checking
+    // the result for isEmpty() is not conclusive.
+    bool inclusiveIntersect(const LayoutRect&);
+
     // Besides non-empty rects, this method also unites empty rects (as points or line segments).
     // For example, union of (100, 100, 0x0) and (200, 200, 50x0) is (100, 100, 150x100).
     void uniteEvenIfEmpty(const LayoutRect&);
 
     void inflateX(LayoutUnit dx)
     {
         m_location.setX(m_location.x() - dx);
         m_size.setWidth(m_size.width() + dx + dx);
     }
     void inflateY(LayoutUnit dy)
@@ skipping 86 matching lines @@
     return IntRect(roundedIntPoint(location), pixelSnappedIntSize(size, location));
 }
 
 // Redeclared here to avoid ODR issues.
 // See platform/testing/GeometryPrinters.h.
 void PrintTo(const LayoutRect&, std::ostream*);
 
 } // namespace blink
 
 #endif // LayoutRect_h