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// 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 CCPageScaleAnimation_h
#define CCPageScaleAnimation_h
#include "base/memory/scoped_ptr.h"
#include "IntSize.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.
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(const IntSize& scrollStart, float pageScaleStart, const IntSize& windowSize, const IntSize& contentSize, double startTime);
// 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(const IntSize& finalScroll, float finalPageScale, 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(const IntSize& anchor, float finalPageScale, double duration);
// Call these functions while the animation is in progress to output the
// current state.
IntSize scrollOffsetAtTime(double time) const;
float pageScaleAtTime(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; }
const IntSize& finalScrollOffset() const { return m_scrollEnd; }
float finalPageScale() const { return m_pageScaleEnd; }
protected:
PageScaleAnimation(const IntSize& scrollStart, float pageScaleStart, const IntSize& windowSize, const IntSize& contentSize, double startTime);
private:
float progressRatioForTime(double time) const;
IntSize scrollOffsetAtRatio(float ratio) const;
float pageScaleAtRatio(float ratio) const;
IntSize m_scrollStart;
float m_pageScaleStart;
IntSize m_windowSize;
IntSize m_contentSize;
bool m_anchorMode;
IntSize m_anchor;
IntSize m_scrollEnd;
float m_pageScaleEnd;
double m_startTime;
double m_duration;
};
} // namespace cc
#endif
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