cc: Rewrite PageScaleAnimation for new coordinate system.

cc/page_scale_animation.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_PAGE_SCALE_ANIMATION_H_
 #define CC_PAGE_SCALE_ANIMATION_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "ui/gfx/size.h"
-#include "ui/gfx/vector2d.h"
+#include "ui/gfx/vector2d_f.h"
 
 namespace cc {
 
 // A small helper class that does the math for zoom animations, primarily for
 // double-tap zoom. Initialize it with starting and ending scroll/page scale
 // positions and an animation length time, then call ...AtTime() at every frame
 // to obtain the current interpolated position.
+//
+// All sizes and vectors in this class's public methods are in the root scroll
+// layer's coordinate space.
 class PageScaleAnimation {
 public:
-    // Construct with the starting page scale and scroll offset (which is in
-    // pageScaleStart space). The window size is the user-viewable area
-    // in pixels.
-    static scoped_ptr<PageScaleAnimation> create(gfx::Vector2d scrollStart, float pageScaleStart, const gfx::Size& windowSize, const gfx::Size& contentSize, double startTime);
+    // Construct with the state at the beginning of the animation.
+    static scoped_ptr<PageScaleAnimation> create(const gfx::Vector2dF& startScrollOffset, float startPageScaleFactor, const gfx::SizeF& viewportSize, const gfx::SizeF& rootLayerSize, double startTime);
+
     ~PageScaleAnimation();
 
     // The following methods initialize the animation. Call one of them
     // immediately after construction to set the final scroll and page scale.
 
-    // Zoom while explicitly specifying the top-left scroll position. The
-    // scroll offset is in finalPageScale coordinates.
-    void zoomTo(gfx::Vector2d finalScroll, float finalPageScale, double duration);
+    // Zoom while explicitly specifying the top-left scroll position.
+    void zoomTo(const gfx::Vector2dF& targetScrollOffset, float targetPageScaleFactor, double duration);
 
-    // Zoom based on a specified onscreen anchor, which will remain at the same
-    // position on the screen throughout the animation. The anchor is in local
-    // space relative to scrollStart.
-    void zoomWithAnchor(gfx::Vector2d anchor, float finalPageScale, double duration);
+    // Zoom based on a specified anchor. The animator will attempt to keep it
+    // at the same position on the physical display throughout the animation,
+    // unless the edges of the root layer are hit. The anchor is specified
+    // as an offset from the content layer.
+    void zoomWithAnchor(const gfx::Vector2dF& anchor, float targetPageScaleFactor, double duration);
 
     // Call these functions while the animation is in progress to output the
     // current state.
-    gfx::Vector2d scrollOffsetAtTime(double time) const;
-    float pageScaleAtTime(double time) const;
+    gfx::Vector2dF scrollOffsetAtTime(double time) const;
+    float pageScaleFactorAtTime(double time) const;
     bool isAnimationCompleteAtTime(double time) const;
 
     // The following methods return state which is invariant throughout the
     // course of the animation.
     double startTime() const { return m_startTime; }
     double duration() const { return m_duration; }
     double endTime() const { return m_startTime + m_duration; }
-    gfx::Vector2d finalScrollOffset() const { return m_scrollEnd; }
-    float finalPageScale() const { return m_pageScaleEnd; }
+    const gfx::Vector2dF& targetScrollOffset() const { return m_targetScrollOffset; }
+    float targetPageScaleFactor() const { return m_targetPageScaleFactor; }
 
 protected:
-    PageScaleAnimation(gfx::Vector2d scrollStart, float pageScaleStart, const gfx::Size& windowSize, const gfx::Size& contentSize, double startTime);
+    PageScaleAnimation(const gfx::Vector2dF& startScrollOffset, float startPageScaleFactor, const gfx::SizeF& viewportSize, const gfx::SizeF& rootLayerSize, double startTime);
 
 private:
-    float progressRatioForTime(double time) const;
-    gfx::Vector2d scrollOffsetAtRatio(float ratio) const;
-    float pageScaleAtRatio(float ratio) const;
+    void clampTargetScrollOffset();
+    void inferTargetScrollOffsetFromStartAnchor();
+    void inferTargetAnchorFromScrollOffsets();
+    gfx::SizeF viewportSizeAtScale(float pageScaleFactor) const;
 
-    gfx::Vector2d m_scrollStart;
-    float m_pageScaleStart;
-    gfx::Size m_windowSize;
-    gfx::Size m_contentSize;
+    float interpAtTime(double time) const;
+    gfx::Vector2dF scrollOffsetAt(float interp) const;
+    gfx::Vector2dF anchorAt(float interp) const;
+    gfx::Vector2dF viewportRelativeAnchorAt(float interp) const;
+    float pageScaleFactorAt(float interp) const;
 
-    bool m_anchorMode;
-    gfx::Vector2d m_anchor;
-    gfx::Vector2d m_scrollEnd;
-    float m_pageScaleEnd;
+    float m_startPageScaleFactor;
+    float m_targetPageScaleFactor;
+    gfx::Vector2dF m_startScrollOffset;
+    gfx::Vector2dF m_targetScrollOffset;
+
+    gfx::Vector2dF m_startAnchor;
+    gfx::Vector2dF m_targetAnchor;
+
+    gfx::SizeF m_viewportSize;
+    gfx::SizeF m_rootLayerSize;
 
     double m_startTime;
     double m_duration;
 };
 
 }  // namespace cc
 
 #endif  // CC_PAGE_SCALE_ANIMATION_H_