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

Source/web/ViewportAnchor.h

Index: Source/web/ViewportAnchor.h
diff --git a/Source/web/ViewportAnchor.h b/Source/web/ViewportAnchor.h
index 8bd0a7b92b1ef0c77917e4b37fc754c2e69e768d..2f912e396f374711baaa563dfc8e18036c50e96d 100644
--- a/Source/web/ViewportAnchor.h
+++ b/Source/web/ViewportAnchor.h
@@ -56,9 +56,11 @@ class ViewportAnchor {
 public:
     explicit ViewportAnchor(EventHandler*);
 
-    void setAnchor(const IntRect& viewRect, const FloatSize& anchorInViewCoords);
+    void setAnchor(const IntRect& innerViewRect, const IntRect& outerViewRect, const FloatSize& anchorInViewCoords);
 
-    IntPoint computeOrigin(const IntSize& currentViewSize) const;
+    IntPoint computeInnerViewportOrigin(const IntSize& innerSize) const;
+
+    IntPoint computeOuterViewportOrigin(const IntPoint& innerOrigin, const IntSize& outerSize) const;

[aelias_OOO_until_Jul13, 2014/09/10 01:46:24]

How about merging these two functions into:

void computeOrigins(const IntSize& innerSize, const IntSize& outerSize, IntSize*
outerScrollOffset, FloatSize pinchViewportOffset);

(pinchViewportOffset would be the vector from outer -> inner, i.e. exactly the
value needed in the PinchViewport class.)

[timav, 2014/09/10 18:22:40]

Will do.

 
 private:
     RawPtrWillBeMember<EventHandler> m_eventHandler;
@@ -70,6 +72,7 @@ private:
 
     FloatSize m_anchorInViewCoords;
     FloatSize m_anchorInNodeCoords;
+    FloatSize m_outerInInnerCoords;

[aelias_OOO_until_Jul13, 2014/09/10 01:46:24]

Please rename this to m_normalizedPinchViewportOffset and invert the sign
(currently it's always negative or zero which seems weird, please make it always
nonnegative instead).

[timav, 2014/09/10 18:22:40]

Yes. The sign was positive in the beginning, but I decided to avoid multiplying
by -1.0. Was not thinking straight.

 };
 
 } // namespace blink