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       gfx::Vector2dF start_scroll_offset,
  29       float start_page_scale_factor,
  30       gfx::SizeF viewport_size,
  31       gfx::SizeF root_layer_size,
  32       double start_time,
  33       scoped_ptr<TimingFunction> timing_function);
  34
  35   ~PageScaleAnimation();
  36
  37   // The following methods initialize the animation. Call one of them
  38   // immediately after construction to set the final scroll and page scale.
  39
  40   // Zoom while explicitly specifying the top-left scroll position.
  41   void ZoomTo(gfx::Vector2dF target_scroll_offset,
  42               float target_page_scale_factor,
  43               double duration);
  44
  45   // Zoom based on a specified anchor. The animator will attempt to keep it
  46   // at the same position on the physical display throughout the animation,
  47   // unless the edges of the root layer are hit. The anchor is specified
  48   // as an offset from the content layer.
  49   void ZoomWithAnchor(gfx::Vector2dF anchor,
  50                       float target_page_scale_factor,
  51                       double duration);
  52
  53   // Call these functions while the animation is in progress to output the
  54   // current state.
  55   gfx::Vector2dF ScrollOffsetAtTime(double time) const;
  56   float PageScaleFactorAtTime(double time) const;
  57   bool IsAnimationCompleteAtTime(double time) const;
  58
  59   // The following methods return state which is invariant throughout the
  60   // course of the animation.
  61   double start_time() const { return start_time_; }
  62   double duration() const { return duration_; }
  63   double end_time() const { return start_time_ + duration_; }
  64   gfx::Vector2dF target_scroll_offset() const { return target_scroll_offset_; }
  65   float target_page_scale_factor() const { return target_page_scale_factor_; }
  66
  67  protected:
  68   PageScaleAnimation(gfx::Vector2dF start_scroll_offset,
  69                      float start_page_scale_factor,
  70                      gfx::SizeF viewport_size,
  71                      gfx::SizeF root_layer_size,
  72                      double start_time,
  73                      scoped_ptr<TimingFunction> timing_function);
  74
  75  private:
  76   void ClampTargetScrollOffset();
  77   void InferTargetScrollOffsetFromStartAnchor();
  78   void InferTargetAnchorFromScrollOffsets();
  79
  80   gfx::SizeF StartViewportSize() const;
  81   gfx::SizeF TargetViewportSize() const;
  82   float InterpAtTime(double time) const;
  83   gfx::SizeF ViewportSizeAt(float interp) const;
  84   gfx::Vector2dF ScrollOffsetAt(float interp) const;
  85   gfx::Vector2dF AnchorAt(float interp) const;
  86   gfx::Vector2dF ViewportRelativeAnchorAt(float interp) const;
  87   float PageScaleFactorAt(float interp) const;
  88
  89   float start_page_scale_factor_;
  90   float target_page_scale_factor_;
  91   gfx::Vector2dF start_scroll_offset_;
  92   gfx::Vector2dF target_scroll_offset_;
  93
  94   gfx::Vector2dF start_anchor_;
  95   gfx::Vector2dF target_anchor_;
  96
  97   gfx::SizeF viewport_size_;
  98   gfx::SizeF root_layer_size_;
  99
 100   double start_time_;
 101   double duration_;
 102
 103   scoped_ptr<TimingFunction> timing_function_;
 104
 105   DISALLOW_COPY_AND_ASSIGN(PageScaleAnimation);
 106 };
 107
 108 }  // namespace cc
 109
 110 #endif  // CC_INPUT_PAGE_SCALE_ANIMATION_H_