OpenCV android camera preview with custom layout?

edit

I want to add a button to the opencvcamera preview, but the button isnt visible and the Preview still fills the whole screen. Is there a way to make a custom layout where the OpenCV camera preview does not fill the whole scrren to display an additional button?

 <LinearLayout  xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        xmlns:opencv="http://schemas.android.com/apk/res-auto"

        android:layout_width="match_parent" 
        android:layout_height="match_parent" 
        android:orientation="horizontal">

        <org.opencv.android.NativeCameraView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:visibility="gone"
            android:id="@+id/HelloOpenCvView"
            opencv:show_fps="true"
            opencv:camera_id="any" />

       <Button
        android:id="@+id/takepicture"  
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:text=" * Take Picture " 
        android:layout_gravity="bottom|right"
        android:layout_margin="10px"
        />

     </LinearLayout >