dictionary - Create an Android GPS tracking application

Question

Recently, I've taken up android development as a hobby and was looking to develop an application that can find and track a users position using Google Maps.

Once the application has a GPS lock, it can track their movements by drawing a route using an overlay class.

I've seen similar applications like Mytracks that are open source but they're too complex for me right now.

Ideally i'd love to create an application that looks like this

Here is my code below without the imports.

What I'm trying to do is create an array of geopoints. Every time the location changes a new geopoint is created. I then try to use a for loop to iterate through each geopoint and draw a path between them.

public class Tracking extends MapActivity implements LocationListener {

LocationManager locman;
LocationListener loclis;
Location Location;
private MapView map;

List<GeoPoint> geoPointsArray = new ArrayList<GeoPoint>();
private MapController controller;
String provider = LocationManager.GPS_PROVIDER;
double lat;
double lon;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.map);
    initMapView();
    initMyLocation();
    locman = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    // locman.requestLocationUpdates(provider,60000, 100,loclis);
    // Location = locman.getLastKnownLocation(provider);

}

/** Find and initialize the map view. */
private void initMapView() {
    map = (MapView) findViewById(R.id.map);
    controller = map.getController();
    map.setSatellite(false);
    map.setBuiltInZoomControls(true);
}

/** Find Current Position on Map. */
private void initMyLocation() {
    final MyLocationOverlay overlay = new MyLocationOverlay(this, map);
    overlay.enableMyLocation();
    overlay.enableCompass(); // does not work in emulator
    overlay.runOnFirstFix(new Runnable() {
        public void run() {
            // Zoom in to current location
            controller.setZoom(24);
            controller.animateTo(overlay.getMyLocation());
        }
    });
    map.getOverlays().add(overlay);
}

@Override
public void onLocationChanged(Location location) {
    if (Location != null) {
        lat = Location.getLatitude();
        lon = Location.getLongitude();
        GeoPoint New_geopoint = new GeoPoint((int) (lat * 1e6),
                (int) (lon * 1e6));
        controller.animateTo(New_geopoint);

    }

}

class MyOverlay extends Overlay {
    public MyOverlay() {
    }

    public void draw(Canvas canvas, MapView mapv, boolean shadow) {
        super.draw(canvas, mapv, shadow);

        Projection projection = map.getProjection();
        Path p = new Path();
        for (int i = 0; i < geoPointsArray.size(); i++) {
            if (i == geoPointsArray.size() - 1) {
                break;
            }
            Point from = new Point();
            Point to = new Point();
            projection.toPixels(geoPointsArray.get(i), from);
            projection.toPixels(geoPointsArray.get(i + 1), to);
            p.moveTo(from.x, from.y);
            p.lineTo(to.x, to.y);
        }
        Paint mPaint = new Paint();
        mPaint.setStyle(Style.STROKE);
        mPaint.setColor(0xFFFF0000);
        mPaint.setAntiAlias(true);
        canvas.drawPath(p, mPaint);
        super.draw(canvas, map, shadow);
    }
}

@Override
public void onProviderDisabled(String provider) {
    // TODO Auto-generated method stub

}

@Override
public void onProviderEnabled(String provider) {
    // TODO Auto-generated method stub

}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
    // TODO Auto-generated method stub

}

@Override
protected boolean isRouteDisplayed() {
    // TODO Auto-generated method stub
    return false;
}
}

The application runs fine without errors but there is no path drawn, the location dot just moves as i move.

Any help would be greatly appreciated Thanks.

Answer 1

The source code for the Android mobile application open-gpstracker which you appreciated is available here.

You can checkout the code using SVN client application or via Git:

• svn checkout http://open-gpstracker.googlecode.com/svn/trunk/ open-gpstracker-read-only
• git clone https://code.google.com/p/open-gpstracker/

Debugging the source code will surely help you.