How to implemennt OnZoomListener on MapView

Question

I would like to have onZoomListener on my MapView. The code below is what I have done. It registers if zoom buttons are tapped. Since all new phones now supports pinch to zoom, this is useless. Does anybody have idea how to do real onZoomListener? Thanks.

   OnZoomListener listener = new OnZoomListener() {
   @Override
   public void onVisibilityChanged(boolean arg0) {
    // TODO Auto-generated method stub

   }
   @Override
   public void onZoom(boolean arg0) {
    Log.d(TAG, "ZOOM CHANGED");
    // TODO Auto-generated method stub

   }
  };

  ZoomButtonsController zoomButton = mapView.getZoomButtonsController();
  zoomButton.setOnZoomListener(listener);

Answer 1

I had to subclass MapView and override dispatchDraw

Here is the code:

 int oldZoomLevel=-1;
 @Override
 public void dispatchDraw(Canvas canvas) {
  super.dispatchDraw(canvas);
  if (getZoomLevel() != oldZoomLevel) {
   Log.d(TAG, "ZOOOMED");
   oldZoomLevel = getZoomLevel();
  }
 }

This blog helped me a lot: http://pa.rezendi.com/2010/03/responding-to-zooms-and-pans-in.html

Above works great. Is there maybe simpler solution? I tried to implement onTouchListener on MapView directly but touch event would be detected only once if onTouchListener would return false. If it would return true, touch would be detected every time, but map zooming and panning wouldn't work.

Answer 2

I put all the code from above together and came up with this class:

package at.blockhaus.wheels.map;

import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.view.MotionEvent;

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

public class CustomMapView extends MapView {

    private int oldZoomLevel = -1;
    private GeoPoint oldCenterGeoPoint;
    private OnPanAndZoomListener mListener;

    public CustomMapView(Context context, String apiKey) {
        super(context, apiKey);
    }

    public CustomMapView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public CustomMapView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    public void setOnPanListener(OnPanAndZoomListener listener) {
        mListener = listener;
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        if (ev.getAction() == MotionEvent.ACTION_UP) {
            GeoPoint centerGeoPoint = this.getMapCenter();
            if (oldCenterGeoPoint == null || 
                    (oldCenterGeoPoint.getLatitudeE6() != centerGeoPoint.getLatitudeE6()) ||
                    (oldCenterGeoPoint.getLongitudeE6() != centerGeoPoint.getLongitudeE6()) ) {
                mListener.onPan();
            }
            oldCenterGeoPoint = this.getMapCenter();
        }
        return super.onTouchEvent(ev);
    }

    @Override
    protected void dispatchDraw(Canvas canvas) {
        super.dispatchDraw(canvas);
        if (getZoomLevel() != oldZoomLevel) {
            mListener.onZoom();
            oldZoomLevel = getZoomLevel();
        }
    }


}

And the corresponding listener interface:

package at.blockhaus.wheels.map;

public interface OnPanAndZoomListener {
    public void onPan();
    public void onZoom();
}

Answer 3

Maybe a bit late, but have you tried with an OnOverlayGestureListener?

http://code.google.com/p/mapview-overlay-manager/wiki/OnOverlayGestureListener

Answer 4

Try via this method

map.setMapListener(new MapListener()
                {
                    ....

                    @Override
                    public boolean onZoom(ZoomEvent event)
                        {

                            return false;
                        }
                });