How to draw an image in the center of the Radio button

Question

How to draw an image in the center of the Radio button

I looked at an example posted at http://bakhtiyor.com/2009/10/iphonish-tabs/ , in fact they posted the Radio button here as a replacement for Tabview.

But the problem is that I can not set the image in the center. It is always aligned to the left.

Here is a screenshot. I want my look to look like this, but instead I want the image to be in the center. enter image description here

This is what my layout XML file looks like

    <?xml version="1.0" encoding="utf-8"?>
<TabHost xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@android:id/tabhost" 
  android:layout_width="fill_parent"
  android:layout_height="fill_parent">

  <LinearLayout android:orientation="vertical"
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent">

    <FrameLayout android:id="@android:id/tabcontent"
      android:layout_width="fill_parent" 
      android:layout_height="wrap_content"
      android:layout_weight="1" 
      android:padding="20dip"/>

    <RadioGroup android:layout_width="fill_parent"
      android:layout_height="wrap_content" 
      android:orientation="horizontal"
      android:checkedButton="@+id/allcontacts"
      android:gravity="center"
      android:id="@+id/contactgroup">


      <RadioButton android:id="@+id/allcontacts" 
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:layout_weight="1"
      android:orientation="vertical"
      android:background="@drawable/button_radio"/>


      <RadioButton
          android:id="@+id/categories"
          android:layout_width="fill_parent"
          android:layout_height="wrap_content"
          android:layout_weight="1"
          android:background="@drawable/button_radio"
          android:orientation="vertical"
          android:layout_gravity="center|right"/>

      <RadioButton android:id="@+id/favourites" 
   android:layout_width="fill_parent"
          android:layout_height="wrap_content"

    android:gravity="center"
    android:orientation="vertical"
      android:layout_weight="1" 
      android:background="@drawable/button_radio"/>

    </RadioGroup>

    <TabWidget android:id="@android:id/tabs"
      android:layout_width="fill_parent" 
      android:layout_height="wrap_content"
      android:layout_weight="0" android:visibility="gone" />
  </LinearLayout>
</TabHost>