Shape画圆形控件

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
    <!-- outer circle -->
    <item>
        <shape android:shape="oval" >
            <solid android:color="#FFACB8C3" />
        </shape>
    </item>
    <!-- inner shadow of outer circle -->
    <item 
        android:bottom="2dp"
        android:left="2dp"
        android:right="2dp"
        android:top="2dp">
        <shape android:shape="oval">
            <solid android:color="#FFbdcad6" />
        </shape>
    </item>
    <item
        android:bottom="3dp"
        android:left="3dp"
        android:right="3dp"
        android:top="3dp">
        <shape android:shape="oval">
            <solid android:color="#FFc3cfd9" />
        </shape>
    
    </item>
    <item
        android:bottom="4dp"
        android:left="4dp"
        android:right="4dp"
        android:top="4dp">
        <shape android:shape="oval">
            <solid android:color="#FFcbd6df" />
        </shape>
    </item>
    <item
        android:bottom="5dp"
        android:left="5dp"
        android:right="5dp"
        android:top="5dp">
        <shape android:shape="oval">
            <solid android:color="#FFd4dee5" />
        </shape>
    </item>
 
    <!-- gap -->
    <item
        android:bottom="6dp"
        android:left="6dp"
        android:right="6dp"
        android:top="6dp">
        <shape android:shape="oval" >
            <solid android:color="#FFdae2e8" />
        </shape>
    </item>
 
    <!-- outer shadow of center circle -->
    <item
        android:bottom="10dp"
        android:left="10dp"
        android:right="10dp"
        android:top="10dp">
        <shape android:shape="oval">
            <solid android:color="#FFced5dc" />
        </shape>
    </item>
    <item
        android:bottom="12dp"
        android:left="12dp"
        android:right="12dp"
        android:top="12dp">
        <shape android:shape="oval">
            <solid android:color="#FFbcc4c9" />
        </shape>
    </item>
    <item
        android:bottom="13dp"
        android:left="13dp"
        android:right="13dp"
        android:top="13dp">
        <shape android:shape="oval">
            <solid android:color="#FFb4bbc0" />
        </shape>
    </item>
    <item
        android:bottom="14dp"
        android:left="14dp"
        android:right="14dp"
        android:top="14dp">
        <shape android:shape="oval">
            <solid android:color="#FFacb3b8" />
        </shape>
    </item>
 
    <!-- center circle -->
    <item
        android:bottom="15dp"
        android:left="15dp"
        android:right="15dp"
        android:top="15dp">
        <shape android:shape="oval">
            <stroke android:width="1dp" android:color="#FFFCFCFC"/>
            <gradient
                android:angle="270"
                android:endColor="#FFCFD7DD"
                android:startColor="#FFF0F5F9" />
        </shape>
    </item>
 
</layer-list>

<Button
        android:id="@+id/button2"
        android:layout_width="300dp"
        android:layout_height="300dp"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:background="@drawable/circle"
        android:textSize="20sp" />