activity_main.xml
<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/fireTopLayout"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#000"
    android:keepScreenOn="true">

    <com.hoineki.mlkittext.CameraSourcePreview
        android:id="@+id/firePreview"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true">

        <com.hoineki.mlkittext.GraphicOverlay
            android:id="@+id/fireFaceOverlay"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_alignParentStart="true"
            android:layout_alignParentTop="true"
            android:layout_alignParentBottom="true"/>
    </com.hoineki.mlkittext.CameraSourcePreview>

    <TextView android:id="@+id/text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingLeft="80dp"
        android:textColor="#FFF"
        android:textSize="20sp"
        android:textStyle="bold" />

    <FrameLayout
        android:id="@+id/control"
        android:layout_width="match_parent"
        android:layout_height="60dp"
        android:layout_alignParentBottom="true"
        android:layout_alignParentStart="true"
        android:layout_toEndOf="@id/firePreview"
        android:background="#000">

        <ToggleButton
            android:id="@+id/facingswitch"
            android:layout_width="48dp"
            android:layout_height="48dp"
            android:layout_gravity="center"
            android:background="@layout/toggle_style"
            android:textOff=""
            android:textOn=""
            android:checked="false" />
    </FrameLayout>
</RelativeLayout>