Android : Android fading circle in background

For the past some time I have been trying to create an animated gradient background to be used with my dialog box. The basic idea is that there will be a tiny dot in the background that will grow in size (and reduce in opacity). This animation has to go on incessantly. So far, this is what I have reached:

<?xml version="1.0" encoding="utf-8"?>
<!-- http://stackoverflow.com/questions/14412361/fade-animation-in-shape-background-gradient -->
<transition xmlns:android="http://schemas.android.com/apk/res/android">
    <!-- unfaded -->
    <item>
        <layer-list>
            <!-- bottom white background color, be be there at all times -->
            <shape android:shape="rectangle">
                <solid android:color="@color/translucent_white_background" />
            </shape>

            <!-- add a small dot shape -->

        </layer-list>
    </item>

    <!-- faded -->
    <item>
        <layer-list>
            <!-- bottom white background color, be be there at all times -->
            <shape android:shape="rectangle">
                <solid android:color="@android:color/white" />
            </shape>

            <!-- add large faded circle, very very large -->

        </layer-list>
    </item>
</transition>  

I could not proceed any further. I tried adding a shape circle with 10dp width and height but all I got was a large oval. I would be glad if you could help me finish this. Mortal Kombat, anyone?