Generate scroll/clip display item hierarchy for SPv2

Source/core/paint/DeprecatedPaintLayer.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 124 matching lines @@
     const DeprecatedPaintLayerReflectionInfo* reflectionInfo() const { return m_reflectionInfo.get(); }
 
     const DeprecatedPaintLayer* root() const
     {
         const DeprecatedPaintLayer* curr = this;
         while (curr->parent())
             curr = curr->parent();
         return curr;
     }
 
-    const LayoutPoint& location() const { ASSERT(!m_needsPositionUpdate); return m_location; }
+    enum LocationQueryBehavior {
+        IncludeScroll,
+        ExcludeScroll
+    };
+    LayoutPoint location(LocationQueryBehavior behavior = IncludeScroll) const { ASSERT(!m_needsPositionUpdate); return behavior == IncludeScroll ? m_location : locationExcludeOverflowScroll(); }
+    // Note: This function is only needed during the transition period to SPv2.
+    // Once we have eliminated layer-based hit testing and clipping,
+    // we can cache the unscrolled location instead.
+    LayoutPoint locationExcludeOverflowScroll() const;

[jbroman, 2015/09/09 19:58:30]

nit: "locationExcludingOverflowScroll", please? I initially read this as
"locationExcludesOverflowScroll" and wondered why it didn't return a boolean.

[trchen, 2015/09/15 04:48:40]

Done.

     // FIXME: size() should ASSERT(!m_needsPositionUpdate) as well, but that fails in some tests,
     // for example, fast/repaint/clipped-relative.html.
     const IntSize& size() const { return m_size; }
     void setSizeHackForLayoutTreeAsText(const IntSize& size) { m_size = size; }
 
     LayoutRect rect() const { return LayoutRect(location(), LayoutSize(size())); }
 
     bool isRootLayer() const { return m_isRootLayer; }
 
     DeprecatedPaintLayerCompositor* compositor() const;
@@ skipping 64 matching lines @@
     DeprecatedPaintLayer* enclosingLayerForPaintInvalidationCrossingFrameBoundaries() const;
 
     bool hasAncestorWithFilterOutsets() const;
 
     bool canUseConvertToLayerCoords() const
     {
         // These LayoutObjects have an impact on their layers without the layoutObjects knowing about it.
         return !layoutObject()->hasTransformRelatedProperty() && !layoutObject()->isSVGRoot();
     }
 
-    void convertToLayerCoords(const DeprecatedPaintLayer* ancestorLayer, LayoutPoint&) const;
+    void convertToLayerCoords(const DeprecatedPaintLayer* ancestorLayer, LayoutPoint&, LocationQueryBehavior = IncludeScroll) const;
     void convertToLayerCoords(const DeprecatedPaintLayer* ancestorLayer, LayoutRect&) const;
 
     // Does the same as convertToLayerCoords() when not in multicol. For multicol, however,
     // convertToLayerCoords() calculates the offset in flow-thread coordinates (what the layout
     // engine uses internally), while this method calculates the visual coordinates; i.e. it figures
     // out which column the layer starts in and adds in the offset. See
     // http://www.chromium.org/developers/design-documents/multi-column-layout for more info.
     LayoutPoint visualOffsetFromAncestor(const DeprecatedPaintLayer* ancestorLayer) const;
 
     // The hitTest() method looks for mouse events by walking layers that intersect the point from front to back.
@@ skipping 499 matching lines @@
 
 } // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showLayerTree(const blink::DeprecatedPaintLayer*);
 void showLayerTree(const blink::LayoutObject*);
 #endif
 
 #endif // Layer_h