app/src/main/res/drawable/circle.xml

<?xml version="1.0" encoding="utf-8"?>
<shape
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval">

    <solid
        android:color="#33000000"/>

    <size
        android:width="120dp"
        android:height="120dp"/>
</shape>