在Android中，如果要设置对象动画并使对象从location1移动到location2，则动画API会找出中间位置（补间），然后使用计时器在适当的时间将适当的移动操作排队到主线程上。除主线程通常用于许多其他事情（绘画，打开文件，响应用户输入等）外，此方法工作正常。排队的计时器通常可能会延迟。编写良好的程序将始终尝试在后台线程（非主线程）中执行尽可能多的操作，但是您始终不能避免使用主线程。要求您对UI对象进行操作的操作始终必须在主线程上完成。同样，许多API会将操作作为线程安全性的形式集中到主线程。
所有视图均在同一GUI线程上绘制，该GUI线程也用于所有用户交互。
因此，如果您需要快速更新GUI或渲染花费太多时间并影响用户体验，请使用SurfaceView。
旋转图片示例：
public class MySurfaceView extends SurfaceView implements SurfaceHolder.Callback {
private DrawThread drawThread;
public MySurfaceView(Context context) {
super(context);
getHolder().addCallback(this);
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
drawThread = new DrawThread(getHolder(), getResources());
drawThread.setRunning(true);
drawThread.start();
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
drawThread.setRunning(false);
while (retry) {
try {
drawThread.join();
retry = false;
} catch (InterruptedException e) {
}
}
}
}
class DrawThread extends Thread{
private boolean runFlag = false;
private SurfaceHolder surfaceHolder;
private Bitmap picture;
private Matrix matrix;
private long prevTime;
public DrawThread(SurfaceHolder surfaceHolder, Resources resources){
this.surfaceHolder = surfaceHolder;
picture = BitmapFactory.decodeResource(resources, R.drawable.icon);
matrix = new Matrix();
matrix.postScale(3.0f, 3.0f);
matrix.postTranslate(100.0f, 100.0f);
prevTime = System.currentTimeMillis();
}
public void setRunning(boolean run) {
runFlag = run;
}
@Override
public void run() {
Canvas canvas;
while (runFlag) {
long now = System.currentTimeMillis();
long elapsedTime = now - prevTime;
if (elapsedTime > 30){
prevTime = now;
matrix.preRotate(2.0f, picture.getWidth() / 2, picture.getHeight() / 2);
}
canvas = null;
try {
canvas = surfaceHolder.lockCanvas(null);
synchronized (surfaceHolder) {
canvas.drawColor(Color.BLACK);
canvas.drawBitmap(picture, matrix, null);
}
}
finally {
if (canvas != null) {
surfaceHolder.unlockCanvasAndPost(canvas);
}
}
}
}
}
活动：
public class SurfaceViewActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new MySurfaceView(this));
}
}