android - Adding Image to an XML Gradient Button

Question

I have created a gradient button using bstyle.xml

<?xml version="1.0" encoding="utf-8"?>

<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle" >
<corners
android:radius="14dp"

/>
<gradient
android:angle="45"
android:centerX="35%"
android:centerColor="#A8A8A8"
android:startColor="#E8E8E8"
android:endColor="#EBFEFF"
android:type="linear"
/>
<padding
android:left="0dp"
android:top="0dp"
android:right="0dp"
android:bottom="0dp"
/>
<size
android:width="60dp"
android:height="55dp"
/>
<stroke
android:width="3dp"
android:color="#919089"
/>
</shape>

In the layout i have set the background of a button to this,it works but what i want is i want to put an image on top of the gradient button(like image button),How can i do it?