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
   9 #include "app/animation.h"
  10 #include "base/time.h"
  11
  12 class AnimationDelegate;
  13
  14 // Linear time bounded animation. As the animation progresses AnimateToState is
  15 // invoked.
  16 class LinearAnimation : public Animation {
  17  public:
  18   // Initializes everything except the duration.
  19   //
  20   // Caller must make sure to call SetDuration() if they use this
  21   // constructor; it is preferable to use the full one, but sometimes
  22   // duration can change between calls to Start() and we need to
  23   // expose this interface.
  24   LinearAnimation(int frame_rate, AnimationDelegate* delegate);
  25
  26   // Initializes all fields.
  27   LinearAnimation(int duration, int frame_rate, AnimationDelegate* delegate);
  28
  29   // Gets the value for the current state, according to the animation curve in
  30   // use. This class provides only for a linear relationship, however subclasses
  31   // can override this to provide others.
  32   virtual double GetCurrentValue() const;
  33
  34   // Skip to the end of the current animation.
  35   void End();
  36
  37   // Changes the length of the animation. This resets the current
  38   // state of the animation to the beginning.
  39   void SetDuration(int duration);
  40
  41  protected:
  42   // Called when the animation progresses. Subclasses override this to
  43   // efficiently update their state.
  44   virtual void AnimateToState(double state) = 0;
  45
  46   // Invoked by the AnimationContainer when the animation is running to advance
  47   // the animation. Use |time_now| rather than Time::Now to avoid multiple
  48   // animations running at the same time diverging.
  49   virtual void Step(base::TimeTicks time_now);
  50
  51   // Overriden to advance to the end (if End was invoked).
  52   virtual void AnimationStopped();
  53
  54   // Overriden to return true if state is not 1.
  55   virtual bool ShouldSendCanceledFromStop();
  56
  57  private:
  58   base::TimeDelta duration_;
  59
  60   // Current state, on a scale from 0.0 to 1.0.
  61   double state_;
  62
  63   // If true, we're in end. This is used to determine if the animation should
  64   // be advanced to the end from AnimationStopped.
  65   bool in_end_;
  66
  67   DISALLOW_COPY_AND_ASSIGN(LinearAnimation);
  68 };
  69
  70 #endif  // APP_LINEAR_ANIMATION_H_