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

use dispatchTouch() method to detect touch events on the map and make sure you call the super() method to carry out the default map touch functions. (Setting onTouchListener will disable the in built events like zooming and panning if you return true from your functiion, and will handle touch only once if you return false.)

in dispatchTouch method, you can check for no of touch points by using event.getPointerCount(). use Action_UP to detect whether the user has zoomed out or not by calling mapview.getZoomLevel(); if you find the zoom level changed, you can carry out your actions.