Grab the Location of LocationClient before it is provided to Maps?

Question

I'm messing with the LocationClient in combination with Google Maps V2, because I wanna integrate it in my app and outdate the LocationListener, LocationSource combination.

One requirement of the app I'm working on is to grab the Location provided from the LocationListener, modify that Location and pass it to Maps via LocationSource.

This is working but I don't know how to manage this using LocationClient. Because it seems that it automatically provide the Location to Maps and there is no point to grab the Location before where I can modify it.

Do I miss something or is that a fact?

Answer 1

LocationClient works similarly to the original Android Location API in that it takes in a LocationListener as an argument to listen for location updates: http://developer.android.com/reference/com/google/android/gms/location/LocationClient.html

The LocationListener.onLocationChanged(Location location) method then gets called by the platform with new locations.

Therefore, you can use the same strategy for passing location updates to the Maps API v2 via the LocationSource and LocationSource.OnLocationChangedListener to control what locations get shown on the map.

First, declare an OnLocationChangedListener object in your Activity:

private OnLocationChangedListener mListener; //Used to update the map with new location

Then, implement LocationSource for your activity, something like:

public class MapScreen extends FragmentActivity implements LocationSource{

In onCreate(), set up the LocationSource for this Activity when you're setting up the Map object:

...
//Show the location on the map
mMap.setMyLocationEnabled(true);
//Set location source
mMap.setLocationSource(this);
...

Then, add the methods required for the LocationSource interface:

/**
 * Maps V2 Location updates
 */
@Override
public void activate(OnLocationChangedListener listener) {
    mListener = listener;       
}

/**
 * Maps V2 Location updates
 */
@Override
public void deactivate() {
     mListener = null;      
}

The final part is passing in the location updates from a normal LocationListener to the Activity implementing the LocationSource:

//Update real-time location on map
if(mListener != null){
    mListener.onLocationChanged(location);
}