Android编程中的逐帧动画性能提升技巧探讨
最编程
2024-02-17 18:43:30
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Android上如果使用逐帧动画的话,可以很方便地使用AnimationDrawable,无论是先声明xml还是直接代码里设置,都是几分钟的事,但使用AnimationDrawable有一个致命的弱点,那就是需要一次性加载所有图片到内存,万一帧数多了或者每张图片都比较大,很容易就报out of memory的异常了,所以有必要进行优化。
这里我们利用View.postDelayed方法延时替换图片,这样就能做到逐帧动画的效果了,然后在替换图片之前,强制回收ImageView当前bitmap就可以减少内存消耗了,废话少说,上代码。
public class SceneAnimation {
private ImageView mImageView;
private int[] mFrameRess;
private int[] mDurations;
private int mDuration;
private int mLastFrameNo;
private long mBreakDelay = 0L;
private int mLastPlayFrameNo = 0;
private boolean isStop = true;
public SceneAnimation(ImageView pImageView, int[] pFrameRess,
int[] pDurations) {
mImageView = pImageView;
mFrameRess = pFrameRess;
mDurations = pDurations;
mLastFrameNo = pFrameRess.length - 1;
// mImageView.setBackgroundResource(mFrameRess[0]);
}
public SceneAnimation(ImageView pImageView, int[] pFrameRess, int pDuration) {
mImageView = pImageView;
mFrameRess = pFrameRess;
mDuration = pDuration;
mLastFrameNo = pFrameRess.length - 1;
// mImageView.setBackgroundResource(mFrameRess[0]);
}
public SceneAnimation(ImageView pImageView, int[] pFrameRess,
int pDuration, long pBreakDelay) {
mImageView = pImageView;
mFrameRess = pFrameRess;
mDuration = pDuration;
mLastFrameNo = pFrameRess.length - 1;
mBreakDelay = pBreakDelay;
// mImageView.setBackgroundResource(mFrameRess[0]);
}
@SuppressWarnings("unused")
private void play(final int pFrameNo) {
mImageView.postDelayed(new Runnable() {
public void run() {
if (pFrameNo != mLastPlayFrameNo) {
recycleImage();
mLastPlayFrameNo = pFrameNo;
}
mImageView.setBackgroundResource(mFrameRess[pFrameNo]);
if (!isStop) {
if (pFrameNo == mLastFrameNo)
play(0);
else
play(pFrameNo + 1);
}
}
}, mDurations[pFrameNo]);
}
private void playConstant(final int pFrameNo) {
mImageView.postDelayed(new Runnable() {
public void run() {
if (pFrameNo != mLastPlayFrameNo) {
recycleImage();
mLastPlayFrameNo = pFrameNo;
}
mImageView.setBackgroundResource(mFrameRess[pFrameNo]);
if (!isStop) {
if (pFrameNo == mLastFrameNo)
playConstant(0);
else
playConstant(pFrameNo + 1);
}
}
}, pFrameNo == mLastFrameNo && mBreakDelay > 0 ? mBreakDelay
: mDuration);
}
public void stopPlay() {
isStop = true;
// recycleImage();
}
public void playConstant() {
isStop = false;
playConstant(mLastPlayFrameNo);
}
private void recycleImage() {
BitmapUtil.recycleImageView(mImageView);
}
public void playOnce(FinishCallback callback) {
isStop = false;
playOnce(callback, 0);
}
private void playOnce(FinishCallback callback, int frameNo) {
mImageView.postDelayed(new Runnable() {
public void run() {
if (frameNo != 0)
recycleImage();
mImageView.setBackgroundResource(mFrameRess[frameNo]);
if (!isStop) {
if (frameNo == mLastFrameNo) {
isStop = true;
if (callback != null)
callback.onFinish(SceneAnimation.this);
} else
playOnce(callback, frameNo + 1);
}
}
}, frameNo == mLastFrameNo && mBreakDelay > 0 ? mBreakDelay
: mDuration);
}
public interface FinishCallback {
public void onFinish(SceneAnimation sceneAnimation);
}
public boolean isRunning() {
return !isStop;
}
}
上面的类提供了两种方法,循环播放和只播放一次,stopPlay是停止当前动画,而mLastPlayFrameNo是当前图片是所有图片中的第几张,循环中当当前的frameNo不等于mLastPlayFrameNo时回收图片,这个相当重要,处理不当可能会报出使用回收后的bitmap的异常,因为有可能用户一开始ImageView设置的src就是第0张,又或者用户停止动画后又想重新播放,那么就会发生上面的情况。
好了,讲述完这个类,看一下如何使用吧,很简单。
SceneAnimation waitAnim = new SceneAnimation(waitImageView, waitResIds, 100); // 指定绑定的ImageView和图片资源数组以及每张图片的延时
waitAnim.playConstant(); // 循环播放
waitAnim.stopPlay(); // 停止播放
逐帧动画优化到这里结束了,后期我们或许可以继续优化,就是防止一个图片帧太大,加载时间过长,我们可以缓存多张,而不是现在的只缓存一张。
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