Question

I’m using the below code to put an overlay on my MapView. For some reason after itterating through the location data it draws the point in the same place.

It seems to be happening on conversion from Location to GeoPoint to Projection:

Location (lat : lon) 51.2651789188385  : -0.5398589372634888
Projection (x : y)   239               : 361
Location (lat : lon) 51.26375198364258 : -0.5417096614837646
Projection (x : y)   239               : 361

Locations are Doubles
GeoPoints are Integers
Projections are screen coordinates.

Could someone please look over the below code and find if i am doing something wrong?

thanks

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.graphics.RectF;
import android.location.Location;
import android.util.Log;

import com.google.android.maps.GeoPoint;
import com.google.android.maps.MapView;
import com.google.android.maps.Overlay;
import com.google.android.maps.Projection;

public class ROverlay extends Overlay {

  private Context context;
  private HashMap<String, Location> friendLocations;
  private ArrayList<LocationData> locD;
  private Location location;
  private GeoPoint locationPoint;

  private Paint paint;
  private Paint backPaint;

  private static int markerRadius = 7;

  /** Get your current location */
    public Location getLocation() {
        return location;
}
/** Set your current location */
public void setLocation(Location location) {
  this.location = location;

  Double latitude = location.getLatitude()*1E6;
  Double longitude = location.getLongitude()*1E6;

  locationPoint = new GeoPoint(latitude.intValue(),longitude.intValue());      
}  

/** Refresh the locations of each of the contacts */
 public void refreshLocation() {
  locD = RMapView.getARR();
 }

   /**
 * Create a new FriendLocationOverlay to show your contact's locations on a map
 * @param _context Parent application context
 */
public ROverlay(Context _context) {
super();

context = _context;
friendLocations = new HashMap<String, Location>();
locD = new ArrayList<LocationData>();
//refreshFriendLocations();

// Create the paint objects
backPaint = new Paint();
backPaint.setARGB(200, 200, 200, 200);
backPaint.setAntiAlias(true);

paint = new Paint();
paint.setDither(true);
paint.setColor(Color.RED);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeJoin(Paint.Join.ROUND);
paint.setStrokeCap(Paint.Cap.ROUND);
paint.setStrokeWidth(5);   
 }

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

// Get the map projection to convert lat/long to screen coordinates
Projection projection = mapView.getProjection();

for (int q = 1; q < locD.size(); q++){
    Double latitude = locD.get(q-1).mLocation.getLatitude()*1e6;
    Double longitude = locD.get(q-1).mLocation.getLongitude()*1e6;
    GeoPoint geopoint = new GeoPoint(latitude.intValue(),longitude.intValue());
    //Log.d("Double", ""+latitude+" : "+longitude);
    //Log.d("Geopoint", ""+geopoint.getLatitudeE6()+" : "+geopoint.getLongitudeE6());
    Point point = new Point();
    projection.toPixels(geopoint, point);

    Double latitude2 = locD.get(q).mLocation.getLatitude()*1e6;
    Double longitude2 = locD.get(q).mLocation.getLongitude()*1e6;
    GeoPoint geopoint2 = new GeoPoint(latitude2.intValue(),longitude2.intValue());
    Point point2 = new Point();
    projection.toPixels(geopoint2, point2); 

    canvas.drawLine(point.x, point.y, point2.x, point2.y, paint);
    canvas.drawPoint(point.x, point.y, paint);
    Log.d("Point", ""+point.x+" : "+point.y);
}
super.draw(canvas, mapView, shadow);
}

@Override
public boolean onTap(GeoPoint point, MapView mapView) {
  // Do not react to screen taps.
  return false;
}
}

</code>

Answer 1

I don’t know what the problem is with this one. I couldn’t get it working and the debug was showing no errors so in the end i used code from the Google Mytracks project to enable the map view and projection problems

http://code.google.com/p/mytracks/