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      1 // Copyright 2011 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CC_INPUT_PAGE_SCALE_ANIMATION_H_
      6 #define CC_INPUT_PAGE_SCALE_ANIMATION_H_
      7 
      8 #include "base/basictypes.h"
      9 #include "base/memory/scoped_ptr.h"
     10 #include "base/time/time.h"
     11 #include "ui/gfx/size.h"
     12 #include "ui/gfx/vector2d_f.h"
     13 
     14 namespace cc {
     15 
     16 class TimingFunction;
     17 
     18 // A small helper class that does the math for zoom animations, primarily for
     19 // double-tap zoom. Initialize it with starting and ending scroll/page scale
     20 // positions and an animation length time, then call ...AtTime() at every frame
     21 // to obtain the current interpolated position. The supplied timing function
     22 // is used to ease the animation.
     23 //
     24 // All sizes and vectors in this class's public methods are in the root scroll
     25 // layer's coordinate space.
     26 class PageScaleAnimation {
     27  public:
     28   // Construct with the state at the beginning of the animation.
     29   static scoped_ptr<PageScaleAnimation> Create(
     30       const gfx::Vector2dF& start_scroll_offset,
     31       float start_page_scale_factor,
     32       const gfx::SizeF& viewport_size,
     33       const gfx::SizeF& root_layer_size,
     34       scoped_ptr<TimingFunction> timing_function);
     35 
     36   ~PageScaleAnimation();
     37 
     38   // The following methods initialize the animation. Call one of them
     39   // immediately after construction to set the final scroll and page scale.
     40 
     41   // Zoom while explicitly specifying the top-left scroll position.
     42   void ZoomTo(const gfx::Vector2dF& target_scroll_offset,
     43               float target_page_scale_factor,
     44               double duration);
     45 
     46   // Zoom based on a specified anchor. The animator will attempt to keep it
     47   // at the same position on the physical display throughout the animation,
     48   // unless the edges of the root layer are hit. The anchor is specified
     49   // as an offset from the content layer.
     50   void ZoomWithAnchor(const gfx::Vector2dF& anchor,
     51                       float target_page_scale_factor,
     52                       double duration);
     53 
     54   // These should be called before the first frame of animation to initialize
     55   // the start time. StartAnimation should only be called once after creation.
     56   bool IsAnimationStarted() const;
     57   void StartAnimation(base::TimeTicks time);
     58 
     59   // Call these functions while the animation is in progress to output the
     60   // current state.
     61   gfx::Vector2dF ScrollOffsetAtTime(base::TimeTicks time) const;
     62   float PageScaleFactorAtTime(base::TimeTicks time) const;
     63   bool IsAnimationCompleteAtTime(base::TimeTicks time) const;
     64 
     65   // The following methods return state which is invariant throughout the
     66   // course of the animation.
     67   base::TimeTicks start_time() const { return start_time_; }
     68   base::TimeDelta duration() const { return duration_; }
     69   base::TimeTicks end_time() const { return start_time_ + duration_; }
     70   gfx::Vector2dF target_scroll_offset() const { return target_scroll_offset_; }
     71   float target_page_scale_factor() const { return target_page_scale_factor_; }
     72 
     73  protected:
     74   PageScaleAnimation(const gfx::Vector2dF& start_scroll_offset,
     75                      float start_page_scale_factor,
     76                      const gfx::SizeF& viewport_size,
     77                      const gfx::SizeF& root_layer_size,
     78                      scoped_ptr<TimingFunction> timing_function);
     79 
     80  private:
     81   void ClampTargetScrollOffset();
     82   void InferTargetScrollOffsetFromStartAnchor();
     83   void InferTargetAnchorFromScrollOffsets();
     84 
     85   gfx::SizeF StartViewportSize() const;
     86   gfx::SizeF TargetViewportSize() const;
     87   float InterpAtTime(base::TimeTicks time) const;
     88   gfx::SizeF ViewportSizeAt(float interp) const;
     89   gfx::Vector2dF ScrollOffsetAt(float interp) const;
     90   gfx::Vector2dF AnchorAt(float interp) const;
     91   gfx::Vector2dF ViewportRelativeAnchorAt(float interp) const;
     92   float PageScaleFactorAt(float interp) const;
     93 
     94   float start_page_scale_factor_;
     95   float target_page_scale_factor_;
     96   gfx::Vector2dF start_scroll_offset_;
     97   gfx::Vector2dF target_scroll_offset_;
     98 
     99   gfx::Vector2dF start_anchor_;
    100   gfx::Vector2dF target_anchor_;
    101 
    102   gfx::SizeF viewport_size_;
    103   gfx::SizeF root_layer_size_;
    104 
    105   base::TimeTicks start_time_;
    106   base::TimeDelta duration_;
    107 
    108   scoped_ptr<TimingFunction> timing_function_;
    109 
    110   DISALLOW_COPY_AND_ASSIGN(PageScaleAnimation);
    111 };
    112 
    113 }  // namespace cc
    114 
    115 #endif  // CC_INPUT_PAGE_SCALE_ANIMATION_H_
    116