Xml

 1.

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >

    <item
        android:drawable="@drawable/add6"
        android:width="50dp"
        android:height="50dp"
        />

</layer-list >

2.

3.

4.