Initial draft - modify ViewportAnchor to know about both inner and outer viewports.

Source/web/ViewportAnchor.h

 /*
  * Copyright (C) 2013 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 38 matching lines @@
 // and an anchor point (in view coordinates, e.g., (0, 0) == viewport origin,
 // (0.5, 0) == viewport top center). The anchor point tracks the underlying DOM
 // node; as the node moves or the view is resized, the viewport anchor maintains
 // its orientation relative to the node, and the viewport origin maintains its
 // orientation relative to the anchor.
 class ViewportAnchor {
     STACK_ALLOCATED();
 public:
     explicit ViewportAnchor(EventHandler*);
 
-    void setAnchor(const IntRect& viewRect, const FloatSize& anchorInViewCoords);
+    void setAnchor(const IntRect& outerViewRect, const IntRect& innerViewRect, const FloatSize& anchorInViewCoords);

[bokan, 2014/09/12 20:53:07]

The inner rect has scale applied to it so it should be a FloatRect (here and
other uses of Inner size/position)

[timav, 2014/09/12 23:33:35]

Acknowledged.

 
-    IntPoint computeOrigin(const IntSize& currentViewSize) const;
+    void computeOrigins(const IntSize& outerSize, const IntSize& innerSize,
+        IntPoint* mainFrameOffset, FloatPoint* pinchViewportOffset) const;
+
+private:
+    FloatPoint getInnerOrigin(const IntSize& innerSize) const;
 
 private:
     RawPtrWillBeMember<EventHandler> m_eventHandler;
 
-    IntRect m_viewRect;
+    // Inner viewport origin in the reference frame of the document in CSS pixels
+    FloatPoint m_pinchViewportInDocument;
+
+    // Inner viewport origin in the reference frame of the outer viewport
+    // normalized to the outer viewport size.
+    FloatSize m_normalizedPinchViewportOffset;
 
     RefPtrWillBeMember<Node> m_anchorNode;
     LayoutRect m_anchorNodeBounds;
 
-    FloatSize m_anchorInViewCoords;
+    FloatSize m_anchorInInnerViewCoords;
     FloatSize m_anchorInNodeCoords;
 };
 
 } // namespace blink
 
  #endif