Android性能优化 _ 帧动画OOM?优化帧动画之SurfaceView逐帧解析
作者:互联网
Android 提供了AnimationDrawable
用于实现帧动画。在动画开始之前,所有帧的图片都被解析并占用内存,一旦动画较复杂帧数较多,在低配置手机上容易发生 OOM。即使不发生 OOM,也会对内存造成不小的压力。下面代码展示了一个帧数为4的帧动画:
原生帧动画
AnimationDrawable drawable = new AnimationDrawable();
drawable.addFrame(getDrawable(R.drawable.frame1), frameDuration);
drawable.addFrame(getDrawable(R.drawable.frame2), frameDuration);
drawable.addFrame(getDrawable(R.drawable.frame3), frameDuration);
drawable.addFrame(getDrawable(R.drawable.frame4), frameDuration);
drawable.setOneShot(true);
ImageView ivFrameAnim = ((ImageView) findViewById(R.id.frame_anim));
ivFrameAnim.setImageDrawable(drawable);
drawable.start();
有没有什么办法让帧动画的数据逐帧加载,而不是一次性全部加载到内存?SurfaceView
就提供了这种能力。
SurfaceView
屏幕的显示机制和帧动画类似,也是一帧一帧的连环画,只不过刷新频率很高,感觉像连续的。为了显示一帧,需要经历计算和渲染两个过程,CPU 先计算出这一帧的图像数据并写入内存,然后调用 OpenGL 命令将内存中数据渲染成图像存放在 GPU Buffer 中,显示设备每隔一定时间从 Buffer 中获取图像并显示。
上述过程中的计算,对于View
来说,就好比在主线程遍历 View树 以决定视图画多大(measure),画在哪(layout),画些啥(draw),计算结果存放在内存中,SurfaceFlinger 会调用 OpenGL 命令将内存中的数据渲染成图像存放在 GPU Buffer 中。每隔16.6ms,显示器从 Buffer 中取出帧并显示。所以自定义 View 可以通过重载onMeasure()
、onLayout()
、onDraw()
来定义帧内容,但不能定义帧刷新频率。
SurfaceView
可以突破这个限制。而且它可以将计算帧数据放到独立的线程中进行。下面是自定义SurfaceView
的模版代码:
public abstract class BaseSurfaceView extends SurfaceView implements SurfaceHolder.Callback {
public static final int DEFAULT_FRAME_DURATION_MILLISECOND = 50;
//用于计算帧数据的线程
private HandlerThread handlerThread;
private Handler handler;
//帧刷新频率
private int frameDuration = DEFAULT_FRAME_DURATION_MILLISECOND;
//用于绘制帧的画布
private Canvas canvas;
private boolean isAlive;
public BaseSurfaceView(Context context) {
super(context);
init();
}
protected void init() {
getHolder().addCallback(this);
//设置透明背景,否则SurfaceView背景是黑的
setBackgroundTransparent();
}
private void setBackgroundTransparent() {
getHolder().setFormat(PixelFormat.TRANSLUCENT);
setZOrderOnTop(true);
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
isAlive = true;
startDrawThread();
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
stopDrawThread();
isAlive = false;
}
//停止帧绘制线程
private void stopDrawThread() {
handlerThread.quit();
handler = null;
}
//启动帧绘制线程
private void startDrawThread() {
handlerThread = new HandlerThread(“SurfaceViewThread”);
handlerThread.start();
handler = new Handler(handlerThread.getLooper());
handler.post(new DrawRunnable());
}
private class DrawRunnable implements Runnable {
@Override
public void run() {
if (!isAlive) {
return;
}
try {
//1.获取画布
canvas = getHolder().lockCanvas();
//2.绘制一帧
onFrameDraw(canvas);
} catch (Exception e) {
e.printStackTrace();
} finally {
//3.将帧数据提交
getHolder().unlockCanvasAndPost(canvas);
//4.一帧绘制结束
onFrameDrawFinish();
}
//不停的将自己推送到绘制线程的消息队列以实现帧刷新
handler.postDelayed(this, frameDuration);
}
}
protected abstract void onFrameDrawFinish();
protected abstract void onFrameDraw(Canvas canvas);
}
- 用
HandlerThread
作为独立帧绘制线程,好处是可以通过与其绑定的Handler
方便地实现“每隔一段时间刷新”,而且在Surface
被销毁的时候可以方便的调用HandlerThread.quit()
来结束线程执行的逻辑。 DrawRunnable.run()
运用模版方法模式定义了绘制算法框架,其中帧绘制逻辑的具体实现被定义成两个抽象方法,推迟到子类中实现,因为绘制的东西是多样的,对于本文来说,绘制的就是一张张图片,所以新建BaseSurfaceView
的子类FrameSurfaceView
:
逐帧解析 & 及时回收
public class FrameSurfaceView extends BaseSurfaceView {
public static final int INVALID_BITMAP_INDEX = Integer.MAX_VALUE;
private List bitmaps = new ArrayList<>();
//帧图片
private Bitmap frameBitmap;
//帧索引
private int bitmapIndex = INVALID_BITMAP_INDEX;
private Paint paint = new Paint();
private BitmapFactory.Options options = new BitmapFactory.Options();
//帧图片原始大小
private Rect srcRect;
//帧图片目标大小
private Rect dstRect = new Rect();
private int defaultWidth;
private int defaultHeight;
public void setDuration(int duration) {
int frameDuration = duration / bitmaps.size();
setFrameDuration(frameDuration);
}
public void setBitmaps(List bitmaps) {
if (bitmaps == null || bitmaps.size() == 0) {
return;
}
this.bitmaps = bitmaps;
//默认情况下,计算第一帧图片的原始大小
getBitmapDimension(bitmaps.get(0));
}
private void getBitmapDimension(Integer integer) {
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(this.getResources(), integer, options);
defaultWidth = options.outWidth;
defaultHeight = options.outHeight;
srcRect = new Rect(0, 0, defaultWidth, defaultHeight);
requestLayout();
}
public FrameSurfaceView(Context context) {
super(context);
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
dstRect.set(0, 0, getWidth(), getHeight());
}
@Override
protected void onFrameDrawFinish() {
//在一帧绘制完后,直接回收它
recycleOneFrame();
}
//回收帧
private void recycleOneFrame() {
if (frameBitmap != null) {
frameBitmap.recycle();
frameBitmap = null;
}
}
@Override
protected void onFrameDraw(Canvas canvas) {
//绘制一帧前需要先清画布,否则所有帧都叠在一起同时显示
clearCanvas(canvas);
if (!isStart()) {
return;
}
if (!isFinish()) {
drawOneFrame(canvas);
} else {
onFrameAnimationEnd();
}
}
//绘制一帧,是张Bitmap
private void drawOneFrame(Canvas canvas) {
frameBitmap = BitmapUtil.decodeOriginBitmap(getResources(), bitmaps.get(bitmapIndex), options);
canvas.drawBitmap(frameBitmap, srcRect, dstRect, paint);
bitmapIndex++;
}
private void onFrameAnimationEnd() {
reset();
}
private void reset() {
bitmapIndex = INVALID_BITMAP_INDEX;
}
//帧动画是否结束
private boolean isFinish() {
return bitmapInde
x >= bitmaps.size();
}
//帧动画是否开始
private boolean isStart() {
return bitmapIndex != INVALID_BITMAP_INDEX;
_BITMAP_INDEX;
}
//帧动画是否结束
private boolean isFinish() {
return bitmapInde[外链图片转存中…(img-Eug6Luq9-1642137464297)]
x >= bitmaps.size();
}
//帧动画是否开始
private boolean isStart() {
return bitmapIndex != INVALID_BITMAP_INDEX;
标签:动画,OOM,void,private,int,drawable,优化,public 来源: https://blog.csdn.net/m0_66144992/article/details/122492234