Android之android.graphics.drawable.Drawable.Callback回调接口

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/*如果你想实现一个扩展子Drawable的动画drawable，那么你可以通过setCallBack(android.graphics.drawable.Drawable.Callback)来把你实现的该接口注册到动画drawable
*中。可以实现对动画的调度和执行
*/
public static interface Callback {
/**
* 当drawable重画时触发，这个点上drawable将被置为不可用（起码drawable展示部分不可用）
* @param 要求重画的drawable
*/
public void invalidateDrawable(Drawable who);

/**
* drawable可以通过该方法来安排动画的下一帧。可以仅仅简单的调用postAtTime(Runnable, Object, long)来实现该方法。参数分别与方法的参数对
*应
* @param who The drawable being scheduled.
* @param what The action to execute.
* @param when The time (in milliseconds) to run
*/
public void scheduleDrawable(Drawable who, Runnable what, long when);

/**
*可以用于取消先前通过scheduleDrawable(Drawable who, Runnable what, long when)调度的某一帧。可以通过调用removeCallbacks(Runnable,Object)来实现
* @param who The drawable being unscheduled.
* @param what The action being unscheduled.
*/
public void unscheduleDrawable(Drawable who, Runnable what);
}