layout.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/constraintlayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >


    <ImageView
        android:id="@+id/image_view"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginStart="80dp"
        android:layout_marginLeft="80dp"
        android:layout_marginEnd="80dp"
        android:layout_marginRight="80dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintDimensionRatio="1"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/change"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Change"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/image_view" />

</androidx.constraintlayout.widget.ConstraintLayout>