Pinch to zoom with Osmdroid

I've written a mapping application which has two activities, one activity displays a Google Maps view, the other displays the equivalent view using osmdroid 3.0.5 jar.开发者_如何学编程

Until now I've been testing on emulators only and the functionality is completely identical in terms of area shown and overlay data. Now I have run the app on a real Gingerbread device, I notice that the Google Maps activity seems to support pinch to zoom, whilst the Osmdroid one doesn't.

I haven't written any code specific to pinch to zoom for the Google side or for Osmdroid. Both activities implement OnTouchListener. Both activities just have a stub for OnTouch like:

@Override
public boolean onTouch(View v, MotionEvent e) {
    // chain it for now
    return false;
}

My mapview in the Osmdroid activity is of the class: org.osmdroid.views.MapView

Does anybody know how to make pinch to zoom work with osmdroid or know of a sample application using osmdroid that I could study and adapt into my app?

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MapView.setBuiltInZoomControls(true);
MapView.setMultiTouchControls(true);

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Osmdroid has the functionality to zoom. You will need to setup a gesturelistener to check for the pinch action, at which point you should call the zoom function in osmdroid. I believe in osmdroid 3.0.5 it is something like

mOsm.getController.setZoomLevel(someNumber) (mOsm is an instance of the map view).

I have the zoom function working for the opposite pinch (you fingers start close together and then expand). I suggest using a MotionEvent (like you are currently doing) and doing something like this:

boolean finished = false;

@Override
public boolean onTouch(View v, MotionEvent e) {

    switch (e.getAction()) {

        case MotionEvent.ACTION_DOWN:
            finished = false;
            break;

        case MotionEvent.ACTION_MOVE:
            finished = false;
            break;

        case MotionEvent.ACTION_UP:
            //action is finishing at this point, so now I can do my refreshActionOnMap();
            if (!finished) 
                refreshActionOnMap();
            break;
    }
    return true;
}

The code I have added deals with the pinch - the finished boolean is something I implemented in my program to figure out when to refresh the map. That should help you out more.

Here is a further explanation of this.

If you are looking for something different, then try reading here. Android has been supporting the pinch action since June 2010 apparently.

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Is it possible not to zoom to the map center but to the middle of users two finger.

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As shameus.burp said, the codeline-

mapView.setMultiTouchControls(true); 

Is working for me in order to pinch for zoom (check at 2021).

Notice that the function that shows zoom-controller (basically it is buttons of (-) and (+)) -

MapView.setBuiltInZoomControls(true);

is deprecated by osmdroid.

So instead, you can use the code line -

mapView.getZoomController().setVisibility(CustomZoomButtonsController.Visibility.ALWAYS);

By default (without adding the last code line) osmdroid is set the zoom-controller to show and fade. Equivalent to

CustomZoomButtonsController.Visibility.SHOW_AND_FADEOUT 

option.