我有一个 FrameLayout,其中包含一个子类 SurfaceView 和一个 ImageView。我想在 ImageView 上做一个 TranslateAnimation。我可以使它工作的唯一方法是向 FrameLayout 添加一个空视图。否则,ImageView 在动画期间被剪裁(到动画开始时 ImageView 位置的边界)。
我很好奇为什么空的兄弟 View 允许 ImageView 正确设置动画。使其工作的行在下面的代码中标有注释。
public class Test5 extends Activity {
private static final String TAG = "Test5";
private MySurfaceView mMSV;
private ImageView mRectView;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mMSV = new MySurfaceView(this);
mRectView = new ImageView(this);
ShapeDrawable sd = new ShapeDrawable(new RectShape());
sd.getPaint().setColor(Color.RED);
sd.setIntrinsicWidth(300);
sd.setIntrinsicHeight(100);
mRectView.setImageDrawable(sd);
FrameLayout frameLayout = new FrameLayout(this);
frameLayout.addView(mMSV);
frameLayout.addView(mRectView, new FrameLayout.LayoutParams(
FrameLayout.LayoutParams.WRAP_CONTENT,
FrameLayout.LayoutParams.WRAP_CONTENT));
// I don't know why the following line prevents clipping during
// animation. It simply adds a vacuous View.
frameLayout.addView(new View(this));
setContentView(frameLayout);
} // onCreate
public class MySurfaceView extends SurfaceView implements
SurfaceHolder.Callback {
public MySurfaceView(Context context) {
super(context);
getHolder().addCallback(this);
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
Canvas can = mMSV.getHolder().lockCanvas();
can.drawColor(Color.GRAY);
mMSV.getHolder().unlockCanvasAndPost(can);
}
@Override
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2,
int arg3) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
if (ev.getAction() == MotionEvent.ACTION_UP) {
Log.v(TAG, String.format("ACTION_UP, w=%d, h=%d", mRectView
.getWidth(), mRectView.getHeight()));
Animation an = new TranslateAnimation(0f, 200f, 0f, 200f);
// Animation an = new RotateAnimation(0f, 90f);
an.setStartOffset(200);
an.setDuration(1000);
mRectView.startAnimation(an);
}
return true;
}
} // MySurfaceView
} // Test5