Centering a background image in Android

Or if you want to use your mipmap image, you should use item instead of bitmap:

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@color/app_bg_color" />
    <item android:drawable="@mipmap/ic_launcher_round"
    android:gravity="center"/>
</layer-list>

You can use BitmapDrawable for the case. Create centered.xml in res/drawable folder:

<bitmap xmlns:android="http://schemas.android.com/apk/res/android"
    android:src="@drawable/your_image"
    android:gravity="center"/>

Then you can use centered drawable as background.