Support bottom-right anchored fixed-position elements during a pinch gesture

cc/layer_impl.h

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_LAYER_IMPL_H_
 #define CC_LAYER_IMPL_H_
 
 #include <string>
 
 #include "base/logging.h"
@@ skipping 134 matching lines @@
     void setOpacity(float);
     float opacity() const;
     bool opacityIsAnimating() const;
 
     void setPosition(const gfx::PointF&);
     const gfx::PointF& position() const { return m_position; }
 
     void setIsContainerForFixedPositionLayers(bool isContainerForFixedPositionLayers) { m_isContainerForFixedPositionLayers = isContainerForFixedPositionLayers; }
     bool isContainerForFixedPositionLayers() const { return m_isContainerForFixedPositionLayers; }
 
+    void setFixedContainerSizeDelta(const gfx::Vector2dF& fixedContainerSizeDelta) { m_fixedContainerSizeDelta = fixedContainerSizeDelta; }
+    const gfx::Vector2dF& fixedContainerSizeDelta() const { return m_fixedContainerSizeDelta; }
+
     void setFixedToContainerLayer(bool fixedToContainerLayer = true) { m_fixedToContainerLayer = fixedToContainerLayer;}
     bool fixedToContainerLayer() const { return m_fixedToContainerLayer; }
 
+    void setFixedToRightEdge(bool fixedToRightEdge) { m_fixedToRightEdge = fixedToRightEdge; }
+    bool fixedToRightEdge() const { return m_fixedToRightEdge; }
+
+    void setFixedToBottomEdge(bool fixedToBottomEdge) { m_fixedToBottomEdge = fixedToBottomEdge; }
+    bool fixedToBottomEdge() const { return m_fixedToBottomEdge; }
+
     void setPreserves3D(bool);
     bool preserves3D() const { return m_preserves3D; }
 
     void setUseParentBackfaceVisibility(bool useParentBackfaceVisibility) { m_useParentBackfaceVisibility = useParentBackfaceVisibility; }
     bool useParentBackfaceVisibility() const { return m_useParentBackfaceVisibility; }
 
     void setSublayerTransform(const gfx::Transform&);
     const gfx::Transform& sublayerTransform() const { return m_sublayerTransform; }
 
     // Debug layer name.
@@ skipping 214 matching lines @@
     bool m_useParentBackfaceVisibility;
     bool m_drawCheckerboardForMissingTiles;
     gfx::Transform m_sublayerTransform;
     gfx::Transform m_transform;
 
     bool m_drawsContent;
     bool m_forceRenderSurface;
 
     // Set for the layer that other layers are fixed to.
     bool m_isContainerForFixedPositionLayers;
+    // This property is effective when m_isContainerForFixedPositionLayers == true,
+    // Currently the only fixed container that resizes is the main frame

[shawnsingh, 2013/03/07 09:57:06]

I imagine that it will be easy to overlook updating this comment if we ever have
to change it.   Also, we should be able to make this patch work for any
container layer that resizes (even though that wouldn't happen yet).  So my vote
is to remove this second sentence in this comment.

+    // scroll layer during a pinch gesture.
+    gfx::Vector2dF m_fixedContainerSizeDelta;
     // This is true if the layer should be fixed to the closest ancestor container.
     bool m_fixedToContainerLayer;
+    // These two properties are effective when m_fixedToContainerLayer == true,
+    // and only make sense if its fixed container resizes itself.
+    bool m_fixedToRightEdge;
+    bool m_fixedToBottomEdge;
 
     gfx::Vector2dF m_scrollDelta;
     gfx::Vector2d m_sentScrollDelta;
     gfx::Vector2d m_maxScrollOffset;
     gfx::Transform m_implTransform;
     gfx::Vector2dF m_lastScrollOffset;
 
     // The global depth value of the center of the layer. This value is used
     // to sort layers from back to front.
     float m_drawDepth;
@@ skipping 28 matching lines @@
     // Group of properties that need to be computed based on the layer tree
     // hierarchy before layers can be drawn.
     DrawProperties<LayerImpl, RenderSurfaceImpl> m_drawProperties;
 
     DISALLOW_COPY_AND_ASSIGN(LayerImpl);
 };
 
 }
 
 #endif  // CC_LAYER_IMPL_H_