為了實現遮罩效果動畫。android本身沒有提供api ，需要自己動手實現。
將view和view的parentLy進行相反方向動畫即可實現該效果：

AnimatorSet animatorSet = new AnimatorSet();
//背景layout
ObjectAnimator bgLy = ObjectAnimator.ofFloat(loginShowContainerLy,
                "translationX", -measureWidth(loginShowContainerLy), 0.0f);
        bgLy.setDuration(showLoginBgEnterTime);
 

        bgLy.setInterpolator(new LinearInterpolator());
ObjectAnimator view = ObjectAnimator.ofFloat(loginShowView,
                "translationX", measureWidth(loginShowView), 0.0f);
        viewLy.setDuration(showLoginBgEnterTime);
        viewLy.setInterpolator(new LinearInterpolator());

animatorSet.play
 
(bgLy).with(view);
animatorSet.start();