tachiyomi/app/src/main/res/layout/fragment_page.xml

<?xml version="1.0" encoding="utf-8"?>

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

    <ProgressBar
        android:id="@+id/progress"
        style="?android:attr/progressBarStyleLarge"
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:layout_gravity="center_vertical|center_horizontal"
        android:visibility="gone" />

        <include layout="@layout/chapter_image"/>

</FrameLayout>