Question

I’m trying to make a custom marker for an OSMdroid map with a custom Overlay class. I think I get it but it gives me a StackOverflowError on the draw contructor

Here’s the code of the main activity

package com.example.osmap1;import java.util.List;

import org.osmdroid.util.GeoPoint;
import org.osmdroid.views.MapController;
import org.osmdroid.views.MapView;
import org.osmdroid.views.overlay.Overlay;

import com.example.osmap1.herramientas.MiOverlay;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;

public class MainActivity extends Activity {
MapView map;
MapController mc;
GeoPoint gp;
List<Overlay> mOverlays;

private static MainActivity mainActivity=null;
public static MainActivity getInstance(){
    if(mainActivity == null){
        mainActivity=new MainActivity();

    }
    return mainActivity;
}

@Override
public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    mainActivity=this;
    map=(MapView)findViewById(R.id.mapView);

    mc=map.getController();
    map.setBuiltInZoomControls(true);
    map.setMultiTouchControls(true);

    addPointToMapOverlay("43.528023","-5.672949");

}

private void addPointToMap (String latitud, String longitud){

    String coordenadas[]={latitud,longitud};
    double lat=Double.parseDouble(coordenadas[0]);
    double lng=Double.parseDouble(coordenadas[1]);
    GeoPoint gp=new GeoPoint((int)lat*1E6,(int)lng*1E6);
    mc.animateTo(gp);
    mc.setZoom(4);
    /*map.invalidate(); no funciona en osm*/
}

private void addPointToMapOverlay (String latitud, String longitud){


    String coordenadas[]={latitud,longitud};
    double lat=Double.parseDouble(coordenadas[0]);
    double lng=Double.parseDouble(coordenadas[1]);
    GeoPoint gp=new GeoPoint((int)lat*1E6,(int)lng*1E6);

    mOverlays=map.getOverlays();
    MiOverlay marker= new MiOverlay(gp);
    mOverlays.add(marker);
    mc.animateTo(gp);
    mc.setZoom(4);
    map.invalidate();
}



@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_main, menu);
    return true;
 }
}

And this is my custom class code

public class MiOverlay extends Overlay{

private GeoPoint punto;


public MiOverlay(GeoPoint point) {

    super(MainActivity.getInstance().getBaseContext());
    this.punto=point;
    // TODO Auto-generated constructor stub
}

@Override
public void draw(Canvas canvas, MapView mapview, boolean shadow) {

    // TODO Auto-generated method stub
    this.draw(canvas, mapview, shadow);

    //se traduce el punto geo localizado a un punto en la pantalla
    Point scrnPoint = new Point();
    mapview.getProjection().toPixels(this.punto, scrnPoint);

    //se construye un bitmap a partir de la imagen
    Bitmap marker = BitmapFactory.decodeResource(MainActivity.getInstance().getResources(),com.example.osmap1.R.drawable.seas);

    //se dibuja la imagen del marker
    canvas.drawBitmap(marker, scrnPoint.x - marker.getWidth() / 2, scrnPoint.y - marker.getHeight() / 2, null);


}

public boolean onTouchEvent(MotionEvent event, MapView mapView) 
{   
    //---when user lifts his finger---
    if (event.getAction() == 1) {                
        GeoPoint p = (GeoPoint) mapView.getProjection().fromPixels(
            (int) event.getX(),
            (int) event.getY());
            Toast.makeText(MainActivity.getInstance().getBaseContext(), 
                p.getLatitudeE6() / 1E6 + "," + 
                p.getLongitudeE6() /1E6 , 
                Toast.LENGTH_SHORT).show();
    }                            
    return false;
}        

}

I think the problem coud be mapview.getProjection().toMapPixels(this.punto, scrnPoint) but I’m not sure… Any sugestion is wellcome

Answer 1

It’s an infinite loop – I admit I don’t quite understand what you’re trying to do, but the draw function calls itself recursively:

@Override
public void draw(Canvas canvas, MapView mapview, boolean shadow) {

    this.draw(canvas, mapview, shadow); // This is the same method!
}

the result, illustrating flow of control, is this:

draw()
 -> draw()
    -> draw()
    ...
    StackOverflowException

perhaps you meant super.draw(canvas, mapview, shadow)?