outline_gradient_shadow_on_circle.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:gravity="center">
        <shape android:shape="oval">
            <gradient
                android:centerColor="#80000000"
                android:endColor="#00000000"
                android:gradientRadius="90"
                android:startColor="#ff000000"
                android:type="radial" />
            <size
                android:width="100dp"
                android:height="100dp" />
        </shape>
    </item>
    <item android:gravity="center">
        <shape android:shape="oval">
            <solid android:color="#fff" />
            <size
                android:width="80dp"
                android:height="80dp" />
        </shape>
    </item>
</layer-list>