ui/gfx/animation/linear_animation.h

   1 // Copyright (c) 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 UI_GFX_ANIMATION_LINEAR_ANIMATION_H_
   6 #define UI_GFX_ANIMATION_LINEAR_ANIMATION_H_
   7
   8 #include "base/time/time.h"
   9 #include "ui/gfx/animation/animation.h"
  10
  11 namespace gfx {
  12
  13 class AnimationDelegate;
  14
  15 // Linear time bounded animation. As the animation progresses AnimateToState is
  16 // invoked.
  17 class GFX_EXPORT LinearAnimation : public Animation {
  18  public:
  19   // Initializes everything except the duration.
  20   //
  21   // Caller must make sure to call SetDuration() if they use this
  22   // constructor; it is preferable to use the full one, but sometimes
  23   // duration can change between calls to Start() and we need to
  24   // expose this interface.
  25   LinearAnimation(int frame_rate, AnimationDelegate* delegate);
  26
  27   // Initializes all fields.
  28   LinearAnimation(int duration, int frame_rate, AnimationDelegate* delegate);
  29
  30   // Gets the value for the current state, according to the animation curve in
  31   // use. This class provides only for a linear relationship, however subclasses
  32   // can override this to provide others.
  33   double GetCurrentValue() const override;
  34
  35   // Change the current state of the animation to |new_value|.
  36   void SetCurrentValue(double new_value);
  37
  38   // Skip to the end of the current animation.
  39   void End();
  40
  41   // Changes the length of the animation. This resets the current
  42   // state of the animation to the beginning.
  43   void SetDuration(int duration);
  44
  45  protected:
  46   // Called when the animation progresses. Subclasses override this to
  47   // efficiently update their state.
  48   virtual void AnimateToState(double state) {}
  49
  50   // Invoked by the AnimationContainer when the animation is running to advance
  51   // the animation. Use |time_now| rather than Time::Now to avoid multiple
  52   // animations running at the same time diverging.
  53   void Step(base::TimeTicks time_now) override;
  54
  55   // Overriden to initialize state.
  56   void AnimationStarted() override;
  57
  58   // Overriden to advance to the end (if End was invoked).
  59   void AnimationStopped() override;
  60
  61   // Overriden to return true if state is not 1.
  62   bool ShouldSendCanceledFromStop() override;
  63
  64  private:
  65   base::TimeDelta duration_;
  66
  67   // Current state, on a scale from 0.0 to 1.0.
  68   double state_;
  69
  70   // If true, we're in end. This is used to determine if the animation should
  71   // be advanced to the end from AnimationStopped.
  72   bool in_end_;
  73
  74   DISALLOW_COPY_AND_ASSIGN(LinearAnimation);
  75 };
  76
  77 }  // namespace gfx
  78
  79 #endif  // APP_LINEAR_ANIMATION_H_