Add crosshair overlay to google map v2

Issue

I'm trying to add an overlay to my google map which is fixed in the center of the screen so users can use it to finely selected a location.

Currently the code below draws a mapview with a centered crosshair image but as the button is below the mapview the center of the map changes and the crosshair no longer represents the center point of the map which has been moved upwards by the height of the button.

I've looked at Android - Showing a crosshair in the center of my Google Map but it seems it is only suitable for v1 :(

<RelativeLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <fragment xmlns:android="http://schemas.android.com/apk/res/android"
     android:id="@+id/locationpicker_map"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:layout_above="@+id/locationpicker_add_venue"
     android:clickable="true" 
     android:layout_weight="1"
     class="com.google.android.gms.maps.SupportMapFragment"/>
        <ImageView
            android:id="@+id/imageView1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/crosshairs"
            android:layout_gravity="center_vertical"
            android:layout_centerInParent="true"/>
        <Button 
        android:id="@+id/locationpicker_add_venue" 
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text = "Add new venue here"
        android:layout_alignParentBottom="true"/>
</RelativeLayout>

Solution

In order to achieve this effect I used a relative layout wrapped around the map fragment with an imageview centered. For the example see below;

<RelativeLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <fragment xmlns:android="http://schemas.android.com/apk/res/android"
     android:id="@+id/locationpicker_map"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:clickable="true" 
     android:layout_weight="1"
     class="com.google.android.gms.maps.SupportMapFragment"/>
        <ImageView
            android:id="@+id/imageView1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/crosshairs"
            android:layout_gravity="center_vertical"
            android:layout_centerInParent="true"/>
        <Button 
        android:id="@+id/locationpicker_add_venue" 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text = "Add new venue here"
        style="@style/Buttonpurple_style"
        android:layout_gravity="center"
        android:layout_centerHorizontal="true" 
        android:layout_alignParentBottom="true"
        />
</RelativeLayout>

Answered By - Garbit