ring-android/app/src/main/res/layout/frag_scan.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_marginTop="@dimen/padding_large">


    <TextView
        android:id="@+id/error_msg_txt"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/error_pane"
        android:gravity="center_vertical|center_horizontal"
        android:padding="16dp"
        android:textColor="@color/white"
        android:textSize="14sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:visibility="gone" />


    <com.journeyapps.barcodescanner.DecoratedBarcodeView
        android:id="@+id/barcode_scanner"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

    </com.journeyapps.barcodescanner.DecoratedBarcodeView>


</androidx.constraintlayout.widget.ConstraintLayout>