app/linear_animation.h

   1 // Copyright (c) 2010 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 // Inspired by NSAnimation
   5
   6 #ifndef APP_LINEAR_ANIMATION_H_
   7 #define APP_LINEAR_ANIMATION_H_
   8 #pragma once
   9
  10 #include "app/animation.h"
  11 #include "base/time.h"
  12
  13 class AnimationDelegate;
  14
  15 // Linear time bounded animation. As the animation progresses AnimateToState is
  16 // invoked.
  17 class 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   virtual double GetCurrentValue() const;
  34
  35   // Skip to the end of the current animation.
  36   void End();
  37
  38   // Changes the length of the animation. This resets the current
  39   // state of the animation to the beginning.
  40   void SetDuration(int duration);
  41
  42  protected:
  43   // Called when the animation progresses. Subclasses override this to
  44   // efficiently update their state.
  45   virtual void AnimateToState(double state) = 0;
  46
  47   // Invoked by the AnimationContainer when the animation is running to advance
  48   // the animation. Use |time_now| rather than Time::Now to avoid multiple
  49   // animations running at the same time diverging.
  50   virtual void Step(base::TimeTicks time_now);
  51
  52   // Overriden to advance to the end (if End was invoked).
  53   virtual void AnimationStopped();
  54
  55   // Overriden to return true if state is not 1.
  56   virtual bool ShouldSendCanceledFromStop();
  57
  58  private:
  59   base::TimeDelta duration_;
  60
  61   // Current state, on a scale from 0.0 to 1.0.
  62   double state_;
  63
  64   // If true, we're in end. This is used to determine if the animation should
  65   // be advanced to the end from AnimationStopped.
  66   bool in_end_;
  67
  68   DISALLOW_COPY_AND_ASSIGN(LinearAnimation);
  69 };
  70
  71 #endif  // APP_LINEAR_ANIMATION_H_