Quelle  activity_crop.xml

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

    <com.google.android.material.appbar.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <com.google.android.material.appbar.MaterialToolbar
            android:id="@+id/crop_toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:contentInsetEnd="0dp"
            app:contentInsetStart="0dp"
            app:title="@string/crop_image_title" />

    </com.google.android.material.appbar.AppBarLayout>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:id="@+id/crop_parent"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">

        <com.canhub.cropper.CropImageView
            android:id="@+id/crop_image"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:background="?android:attr/colorBackground"
            app:cropBorderCornerLength="20dp"
            app:cropBorderCornerOffset="0dp"
            app:cropBorderLineColor="#88FFFFFF"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

        <com.google.android.material.floatingactionbutton.ExtendedFloatingActionButton
            android:id="@+id/floating"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="@dimen/grid_unit_x2"
            android:clickable="true"
            android:contentDescription="@string/crop"
            android:focusable="true"
            android:text="@string/crop"
            app:icon="@drawable/ic_crop_outline"
            app:layout_anchor="@id/crop_parent"
            app:layout_anchorGravity="bottom|right"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintRight_toRightOf="parent" />

    </androidx.constraintlayout.widget.ConstraintLayout>

</androidx.coordinatorlayout.widget.CoordinatorLayout>