res/layout/fragment_preview.xml

<!--
  ~ Copyright (C) 2021 The Android Open Source Project
  ~
  ~ Licensed under the Apache License, Version 2.0 (the "License");
  ~ you may not use this file except in compliance with the License.
  ~ You may obtain a copy of the License at
  ~
  ~      http://www.apache.org/licenses/LICENSE-2.0
  ~
  ~ Unless required by applicable law or agreed to in writing, software
  ~ distributed under the License is distributed on an "AS IS" BASIS,
  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  ~ See the License for the specific language governing permissions and
  ~ limitations under the License.
  -->

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
             android:layout_width="match_parent"
             android:layout_height="match_parent">

    <androidx.viewpager2.widget.ViewPager2
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/preview_viewPager"
        android:layout_gravity="center"/>

    <Button
        android:id="@+id/preview_add_button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal|bottom"
        android:layout_marginHorizontal="@dimen/preview_buttons_margin_horizontal"
        android:layout_marginBottom="@dimen/preview_buttons_margin_bottom"
        android:backgroundTint="@color/preview_add_button_background_color"
        android:text="@string/add"
        android:textAllCaps="false"
        android:textColor="@color/preview_buttons_text_color"
        android:textSize="@dimen/preview_buttons_text_size"/>
</FrameLayout>