Android AnimationDrawable并知道动画何时结束

Question

我想用几个图像文件制作一个动画，为此，AnimationDrawable效果很好。但是，我需要知道动画何时开始以及何时结束（即添加诸如Animation.AnimationListener之类的侦听器）。搜索答案后，我很难过AnimationDrawable不支持侦听器。

有谁知道如何在Android上使用侦听器创建逐帧图像动画？

Answer 1

我需要知道一次完成的AnimationDrawable何时完成，而不必将AnimationDrawable子类化，因为我必须以XML设置动画列表。我写了这个课，并在Gingerbread和ICS上进行了测试。它可以很容易地扩展以在每个帧上提供回调。/** * Provides a callback when a non-looping {@link AnimationDrawable} completes its animation sequence. More precisely, * {@link #onAnimationComplete()} is triggered when {@link View#invalidateDrawable(Drawable)} has been called on the * last frame. *  * @author Benedict Lau */public abstract class AnimationDrawableCallback implements Callback {    /**     * The last frame of {@link Drawable} in the {@link AnimationDrawable}.     */    private Drawable mLastFrame;    /**     * The client's {@link Callback} implementation. All calls are proxied to this wrapped {@link Callback}     * implementation after intercepting the events we need.     */    private Callback mWrappedCallback;    /**     * Flag to ensure that {@link #onAnimationComplete()} is called only once, since     * {@link #invalidateDrawable(Drawable)} may be called multiple times.     */    private boolean mIsCallbackTriggered = false;    /**     *      * @param animationDrawable     *            the {@link AnimationDrawable}.     * @param callback     *            the client's {@link Callback} implementation. This is usually the {@link View} the has the     *            {@link AnimationDrawable} as background.     */    public AnimationDrawableCallback(AnimationDrawable animationDrawable, Callback callback) {        mLastFrame = animationDrawable.getFrame(animationDrawable.getNumberOfFrames() - 1);        mWrappedCallback = callback;    }    @Override    public void invalidateDrawable(Drawable who) {        if (mWrappedCallback != null) {            mWrappedCallback.invalidateDrawable(who);        }        if (!mIsCallbackTriggered && mLastFrame != null && mLastFrame.equals(who.getCurrent())) {            mIsCallbackTriggered = true;            onAnimationComplete();        }    }    @Override    public void scheduleDrawable(Drawable who, Runnable what, long when) {        if (mWrappedCallback != null) {            mWrappedCallback.scheduleDrawable(who, what, when);        }    }    @Override    public void unscheduleDrawable(Drawable who, Runnable what) {        if (mWrappedCallback != null) {            mWrappedCallback.unscheduleDrawable(who, what);        }    }    //    // Public methods.    //    /**     * Callback triggered when {@link View#invalidateDrawable(Drawable)} has been called on the last frame, which marks     * the end of a non-looping animation sequence.     */    public abstract void onAnimationComplete();}这是使用方法。AnimationDrawable countdownAnimation = (AnimationDrawable) mStartButton.getBackground();countdownAnimation.setCallback(new AnimationDrawableCallback(countdownAnimation, mStartButton) {    @Override    public void onAnimationComplete() {        // TODO Do something.    }});countdownAnimation.start();

Answer 2

通过重写AnimationDrawable类中的selectDrawable方法，可以轻松跟踪动画结束。完整的代码如下：public class AnimationDrawable2 extends AnimationDrawable{    public interface IAnimationFinishListener    {        void onAnimationFinished();    }    private boolean finished = false;    private IAnimationFinishListener animationFinishListener;    public IAnimationFinishListener getAnimationFinishListener()    {        return animationFinishListener;    }    public void setAnimationFinishListener(IAnimationFinishListener animationFinishListener)    {        this.animationFinishListener = animationFinishListener;    }    @Override    public boolean selectDrawable(int idx)    {        boolean ret = super.selectDrawable(idx);        if ((idx != 0) && (idx == getNumberOfFrames() - 1))        {            if (!finished)            {                finished = true;                if (animationFinishListener != null) animationFinishListener.onAnimationFinished();            }        }        return ret;    }}