Ripple水波纹

#Material Design使用

1. ripple水波纹
2. BottomNavigationView

##1.Ripple水波纹效果 爸爸原文链接

1. 继承关系
   java.lang.Object
   ↳ android.graphics.drawable.Drawable
   ↳ android.graphics.drawable.LayerDrawable
   ↳ android.graphics.drawable.RippleDrawable

2. Added in API level 21(android 5.0)

3. ripple配合selector使用可以创造出更加多变的点击反馈效果

<?xml version="1.0" encoding="utf-8"?>
<ripple xmlns:android="http://schemas.android.com/apk/res/android"
    android:color="#721632">
    <item android:state_pressed="false">
        <shape android:shape="rectangle">
            <solid android:color="@color/white"/>
        </shape>
    </item>
</ripple>