frame to mask underling view

gistfile1.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_height="wrap_content" android:layout_width="fill_parent">

    <!-- this can be any layout that you want to mask -->
    <LinearLayout android:id="@+id/mainLayout"
        android:layout_height="wrap_content"
        android:layout_width="fill_parent" android:orientation="vertical"
        android:background="@android:color/white">

        <TextView android:layout_height="wrap_content"
            android:layout_width="wrap_content" android:layout_gravity="center"
            android:text="Random text..." />

    </LinearLayout>

    <!-- FRAME TO MASK UNDERLYING VIEW -->
    <ImageView android:layout_height="fill_parent" 
        android:layout_width="fill_parent" 
        android:background="@drawable/grey_frame"
        android:layout_alignTop="@+id/mainLayout"
        android:layout_alignBottom="@+id/mainLayout" />

</RelativeLayout>