BayernMessenger/vector/src/main/res/layout/activity_media_viewer.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
    android:orientation="vertical">

    <androidx.appcompat.widget.Toolbar
        android:id="@+id/mediaViewerToolbar"
        style="@style/VectorToolbarStyle"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
        app:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar" />

    <com.github.piasy.biv.view.BigImageView
        android:id="@+id/mediaViewerImageView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:failureImageInitScaleType="center"
        app:optimizeDisplay="true" />

</LinearLayout>