cc/input/page_scale_animation.h

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