session-android/res/layout/zooming_image_view.xml

<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android"
       xmlns:tools="http://schemas.android.com/tools"
       tools:context="org.thoughtcrime.securesms.components.ZoomingImageView">

    <com.github.chrisbanes.photoview.PhotoView android:id="@+id/image_view"
                                               android:layout_width="match_parent"
                                               android:layout_height="match_parent"
                                               android:visibility="visible"/>

    <com.davemorrissey.labs.subscaleview.SubsamplingScaleImageView
            android:id="@+id/subsampling_image_view"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:visibility="gone"/>

</merge>