<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/preview_imageview"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_gravity="center"
    android:orientation="vertical"
    >

    <ImageView
        android:id="@+id/preview_theme_image"
        android:layout_width="@dimen/preview_image_width"
        android:layout_height="@dimen/preview_image_height"
        android:layout_gravity="center"
        android:contentDescription="@string/preview_content"
        android:src="@null" 
            android:layout_marginBottom="10dp"
    android:layout_marginLeft="20dp"
    android:layout_marginRight="20dp"
    android:layout_marginTop="10dp"/>

</LinearLayout>