<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.lukas.music.InstrumentView
        android:layout_width="300dp"
        android:layout_height="300dp"
        android:paddingBottom="40dp"
        app:exampleDimension="24sp"
        app:exampleString="Hello, InstrumentView" />

</FrameLayout>