You can generate circular gradient with the following code:
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" >
<gradient
android:centerColor="#c1c1c1"
android:endColor="#4f4f4f"
android:gradientRadius="400"
android:startColor="#c1c1c1"
android:type="radial" >
</gradient>
</shape>
But how would one draw elliptical gradient in android? I.e. different radius for X and Y?