Question

Hey. I am having trouble setting up the OSMdroid library to display OpenSourceMaps. I am working on an activity that will allow the user to see a map of their current location wit buttons to allow the user to switch between normal google maps view, terrain google maps view, and openstreetmaps view. I am currently using the JAR file and just adding it to the build path of my project. It compiles fine however I don’t understand how to use the library. There are very few tutorials/directions online. Do I need to make an IMapView tag in the layout and use it like a Google Map view? How do I switch the layout tiles from normal google maps view?

If someone could just give me a very short walkthrough of how this library works it would be much appreciated. I have been coding in JAVA for numerous years so I just need an english description of what I need to do.

Thanks in advance.

Answer 1

I managed to get osmdroid working in a project, but had to have the Google and the OSM views in different activities as if you switch a Mapview from Google to OSM and then try to go back to Google, I got a runtime error saying something like “only one mapview allowed per activity”. This results in a lot of duplicate code but it does run OK.

Use the latest osmdroid-android-3.0.3.jar, it’s much simpler for drawing overlays. You’ll also need to include slf4j-android-1.5.8.jar. For what it’s worth here is the code for the lashed up demo that used to start with. It’s got a location listener and draws a very simple overlay (line across the screen) If you are familiar with Google Maps, you should be able to adapt it for your purpose.

package osmdemo.demo;

import java.util.List;

import org.osmdroid.tileprovider.tilesource.TileSourceFactory;
import org.osmdroid.util.GeoPoint;
import org.osmdroid.views.MapController;
import org.osmdroid.views.MapView;
import org.osmdroid.views.MapView.Projection;
import org.osmdroid.views.overlay.Overlay;
import org.osmdroid.views.util.constants.MapViewConstants;

import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.Paint.Style;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;

public class DemoMap extends Activity implements LocationListener,
        MapViewConstants {

    private MapView mapView;
    private MapController mapController;
    private MapOverlay mmapOverlay = null;
    private LocationManager mLocMgr;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.copymain);

        mapView = (MapView) this.findViewById(R.id.mapview);
        mapView.setTileSource(TileSourceFactory.MAPNIK);
        mapView.setBuiltInZoomControls(true);
        mapView.setMultiTouchControls(true);

        mapController = this.mapView.getController();
        mapController.setZoom(15);
        GeoPoint point2 = new GeoPoint(53554070, -2959520);
        mapController.setCenter(point2);
        mLocMgr = (LocationManager) getSystemService(LOCATION_SERVICE);
        mLocMgr.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1000, 100,
                this);
        this.mmapOverlay = new MapOverlay(this);
        List<Overlay> listOfOverlays = mapView.getOverlays();
        listOfOverlays.add(mmapOverlay);
        mapView.invalidate();
    }

    public void onLocationChanged(Location location) {

        int lat = (int) (location.getLatitude() * 1E6);
        int lng = (int) (location.getLongitude() * 1E6);
        GeoPoint gpt = new GeoPoint(lat, lng);
        mapController.setCenter(gpt);
        mapView.invalidate();
    }

    public class MapOverlay extends org.osmdroid.views.overlay.Overlay {

        public MapOverlay(Context ctx) {
            super(ctx);
            // TODO Auto-generated constructor stub
        }

        @Override
        protected void draw(Canvas pC, MapView pOsmv, boolean shadow) {
            if (shadow)
                return;

            Paint lp3;
            lp3 = new Paint();
            lp3.setColor(Color.RED);
            lp3.setAntiAlias(true);
            lp3.setStyle(Style.STROKE);
            lp3.setStrokeWidth(1);
            lp3.setTextAlign(Paint.Align.LEFT);
            lp3.setTextSize(12);
            final Rect viewportRect = new Rect();
            final Projection projection = pOsmv.getProjection();
            viewportRect.set(projection.getScreenRect());
            // Draw a line from one corner to the other
            pC.drawLine(viewportRect.left, viewportRect.top,
                    viewportRect.right, viewportRect.bottom, lp3);
        }

    }

    @Override
    public void onProviderDisabled(String arg0) {}

    @Override
    public void onProviderEnabled(String provider) {}

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {}

}

And the xml (copymain.xml)

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
    <org.osmdroid.views.MapView
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="fill_parent" 
        android:layout_height="fill_parent"
        android:id="@+id/mapview"
        ></org.osmdroid.views.MapView>
</LinearLayout>