arcanechat-android/res/layout/activity_registration_qr.xml

<?xml version="1.0" encoding="UTF-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center_horizontal"
    tools:context=".WelcomeActivity">

    <androidx.legacy.widget.Space
        android:layout_weight="1"
        android:layout_width="match_parent"
        android:layout_height="0dp"/>

    <ImageView
        android:id="@+id/welcome_icon"
        android:layout_width="128dp"
        android:layout_height="128dp"
        android:src="@drawable/intro1"
        android:padding="8dp"
        tools:ignore="contentDescription"/>

    <TextView
        android:id="@+id/welcome_header"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:padding="16dp"
        android:text="@string/qrscan_title"
        android:textSize="22sp"
        android:textStyle="bold"/>

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="6"
        android:layout_marginStart="24dp"
        android:layout_marginEnd="24dp"
        android:orientation="vertical">

        <com.journeyapps.barcodescanner.CompoundBarcodeView
            android:id="@+id/zxing_barcode_scanner"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_alignParentBottom="true" />

    </RelativeLayout>

    <androidx.legacy.widget.Space
        android:layout_weight="1"
        android:layout_width="match_parent"
        android:layout_height="0dp"/>

</LinearLayout>