fab.xml

<ImageView
    android:id="@+id/mainly_image"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:src="@drawable/img_tenis"
    app:layout_constraintDimensionRatio="H,5:2"
    tools:ignore="ContentDescription" />

<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab"
    style="@style/FavoriteFAB"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    app:layout_constraintBottom_toBottomOf="@id/mainly_image"
    app:layout_constraintEnd_toEndOf="@id/end_margin"
    app:layout_constraintTop_toBottomOf="@id/mainly_image" />