<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true">
        <shape android:shape="rectangle" >
            <solid android:color="@color/color_state_pressed" />
            <corners android:radius="500dp"/>
            <padding android:bottom="@dimen/_2sdp"
                android:left="@dimen/_2sdp"
                android:right="@dimen/_2sdp"
                android:top="@dimen/_2sdp"/>
        </shape>
    </item>
    <item android:drawable="@drawable/transparent" />
</selector>