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 "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_