Saving MapFragment (Maps v2) State in Android

Question

I\'m working with the new GoogleMaps API (v2) and have some problems with the fragment. I have two fragments in my app (Map, List) and the user can switch between them. Work

Answer 1

How can I accomplish this?

If you replace() a fragment, the old fragment's views are destroyed, which takes out your MapView and, presumably, the CameraPosition.

onSaveInstanceState() is mostly for configuration changes, such as screen rotations. MapFragment and SupportMapFragment already retain the CameraPosition (which, BTW, is Parcelable, so you can save the whole object in the Bundle rather than piecemeal).

You could consider using show() and hide() instead of replace(), so the fragment and its views sticks around.

Answer 2

I solved this problem by holding on to a reference to the CameraPosition on the map in the onDestroyView() method of the fragment; then using that CameraPosition when reinstatiating the map.

The context of my solution has it's own quirks, but essentially I have a map fragment nested within another fragment (which I'm hanging on to, even after it get's replaced). So this is the code in the parent fragment's onActivityCreated() method:

    GoogleMapOptions mapOptions = new GoogleMapOptions();
    if(_savedCameraPosition != null)
    {
        mapOptions.camera(_savedCameraPosition);
    }
    else
    {
        // Centre on Australia
        mapOptions.camera(CameraPosition.fromLatLngZoom(new LatLng(-24.25, 133.25), 15));
    }
    _mapFragment = new SupportMapFragment().newInstance(mapOptions);

    FragmentTransaction fragmentTransaction = getFragmentManager().beginTransaction();
    fragmentTransaction.add(R.id.map_holder, _mapFragment);
    fragmentTransaction.commit();

Then later in the same class I have:

@Override
public void onDestroyView()
{
    super.onDestroyView();
    _savedCameraPosition = _map.getCameraPosition();
}