Android Camera showing corner border

[Sim Kim]

I am creating an application where I want to restrict the camera preview to about 80% of camera screen. I could accomplish it using the layout_weight=0.8 . Now I need to implement border at the corner of the camera preview.

I have attached a snapshot of what I really want to accomplish. The borders shown in red color is what I really want . Any pointer will be helpful.

Here is how I have reduced camera image to 80%.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal" android:layout_width="match_parent"
android:layout_height="match_parent" android:gravity="center"
android:weightSum="1.0">
<LinearLayout android:orientation="vertical" android:id="@+id/surfaceparent"
    android:layout_width="0dp" android:layout_height="match_parent"
    android:layout_weight="0.8" android:gravity="center"
    android:weightSum="1.0">
    <SurfaceView android:id="@+id/camera_preview"
        android:layout_width="fill_parent" android:layout_height="0dp"
        android:layout_weight="0.8">
    </SurfaceView>
</LinearLayout>
</LinearLayout>

Please see the attached image of what I really want.