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

    <rotate
        android:duration="4000"
        android:fromDegrees="0"
        android:pivotX="50%"
        android:pivotY="50%"
        android:toDegrees="360" />

</set>