在多数情况下，你需要在view的xml定义中，定义它的背景：
- android:attr/selectableItemBackground 有界限的波纹
-
android:attr/selectableItemBackgroundBorderless 延伸到view之外的波纹 note：该属性为api21添加
或者，你可以用xml定义一个RippleDrawable类型的资源，并使用波纹属性。
你可以指定一个颜色给RippleDrawable对象，以改变它的默认触摸反馈颜色，使用主题的android:colorControlHighlight属性。
Use the Reveal Effect 使用展现效果
ViewAnimationUtils.createCircularReveal()方法使您能够激活一个循环显示或隐藏一个视图。
显示：// previously invisible view View myView = findViewById(R.id.my_view); // get the center for the clipping circle int cx = (myView.getLeft() + myView.getRight()) / 2; int cy = (myView.getTop() + myView.getBottom()) / 2; // get the final radius for the clipping circle int finalRadius = myView.getWidth(); // create and start the animator for this view // (the start radius is zero) Animator anim = ViewAnimationUtils.createCircularReveal(myView, cx, cy, 0, finalRadius); anim.start(); 隐藏 // previously visible view final View myView = findViewById(R.id.my_view); // get the center for the clipping circle int cx = (myView.getLeft() + myView.getRight()) / 2; int cy = (myView.getTop() + myView.getBottom()) / 2; // get the initial radius for the clipping circle int initialRadius = myView.getWidth(); // create the animation (the final radius is zero) Animator anim = ViewAnimationUtils.createCircularReveal(myView, cx, cy, initialRadius, 0); // make the view invisible when the animation is done anim.addListener(new AnimatorListenerAdapter() { @Override public void onAnimationEnd(Animator animation) { super.onAnimationEnd(animation); myView.setVisibility(View.INVISIBLE); } }); // start the animation anim.start();Customize Activity Transitions 定义Activity的过渡动画
