Android屬性動畫設定中心點

public static void rotateIn(RelativeLayout layout, long delay) {
    ObjectAnimator rotate = ObjectAnimator.ofFloat(layout, "rotation", -f, f);
    layout.setPivotX(layout.getWidth()/);
    layout.setPivotY(layout.getHeight());
    //顯示的調用invalidate
    layout.invalidate();
    rotate.setDuration();
    rotate.setStartDelay(delay);
    rotate.addListener(new MyAnimationListener2());
    rotate.start();
}