session-android/res/layout/mediapicker_media_item.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginRight="2dp"
    android:layout_marginBottom="2dp"
    android:animateLayoutChanges="true">

    <org.thoughtcrime.securesms.components.SquareImageView
        android:id="@+id/mediapicker_image_item_thumbnail"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:adjustViewBounds="true"
        android:scaleType="centerCrop"
        tools:src="@drawable/empty_inbox_1"/>

    <View
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="?mediapicker_image_outline" />

    <FrameLayout
        android:id="@+id/mediapicker_play_overlay"
        android:layout_width="36dp"
        android:layout_height="36dp"
        android:background="@drawable/circle_white"
        android:layout_gravity="center"
        android:longClickable="false"
        android:visibility="gone"
        tools:visibility="gone">

        <ImageView
            android:layout_width="15dp"
            android:layout_height="18dp"
            android:layout_gravity="center"
            android:layout_marginLeft="2dp"
            android:tint="@color/core_blue"
            android:scaleType="fitXY"
            app:srcCompat="@drawable/triangle_right" />

    </FrameLayout>

    <View
        android:id="@+id/mediapicker_select_overlay"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/transparent_black_90" />

    <ImageView
        android:id="@+id/mediapicker_select_on"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="top|right|end"
        android:padding="6dp"
        android:src="@drawable/ic_select_on"
        android:visibility="gone"
        tools:visibility="visible" />

    <ImageView
        android:id="@+id/mediapicker_select_off"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="top|right|end"
        android:padding="6dp"
        android:src="@drawable/ic_select_off"
        android:visibility="gone" />

</FrameLayout>