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495

answers:

1

In V2 there was a way to limit panning/dragging so the map stays within certain bounds. How is that done in V3?

Let's say I want the users to only look at Europe. I've already limited the zoom, but if I allow dragging (which I have to in this case, for other reasons) then the user can pan beyond the area I want to show.

Please give working example or code snippet - I'm not an expert coder...

Thanks!

+3  A: 

The trick is to listen to the dragend event, and if the map is dragged outside the allowed bounds, move it back inside. If you define your allowed bounds as a LatLngBounds object, you can use the contains() method, since it returns true if the given lat/lng argument is within the bounds.

It is also important to limit the zoom level, but it seems you are already doing this.

Therefore, you may want to try the following example:

<!DOCTYPE html>
<html> 
<head> 
   <meta http-equiv="content-type" content="text/html; charset=UTF-8"/> 
   <title>Google Maps JavaScript API v3 Example: Limit Panning</title> 
   <script type="text/javascript" 
           src="http://maps.google.com/maps/api/js?sensor=false"&gt;&lt;/script&gt;
</head> 
<body> 
   <div id="map" style="width: 400px; height: 300px;"></div> 

   <script type="text/javascript"> 

   var minZoomLevel = 5;

   var map = new google.maps.Map(document.getElementById('map'), {
      zoom: minZoomLevel,
      center: new google.maps.LatLng(38.50, -90.50),
      mapTypeId: google.maps.MapTypeId.ROADMAP
   });

   // Bounds for North America
   var allowedBounds = new google.maps.LatLngBounds(
     new google.maps.LatLng(28.70, -127.50), 
     new google.maps.LatLng(48.85, -55.90));

   // Listen for the dragend event
   google.maps.event.addListener(map, 'dragend', function() {
     if (allowedBounds.contains(map.getCenter())) return;

     // Out of bounds - Move the map back within the bounds

     var c = map.getCenter(),
         x = c.lng(),
         y = c.lat(),
         maxX = allowedBounds.getNorthEast().lng(),
         maxY = allowedBounds.getNorthEast().lat(),
         minX = allowedBounds.getSouthWest().lng(),
         minY = allowedBounds.getSouthWest().lat();

     if (x < minX) x = minX;
     if (x > maxX) x = maxX;
     if (y < minY) y = minY;
     if (y > maxY) y = maxY;

     map.setCenter(new google.maps.LatLng(y, x));
   });

   // Limit the zoom level
   google.maps.event.addListener(map, 'zoom_changed', function() {
     if (map.getZoom() < minZoomLevel) map.setZoom(minZoomLevel);
   });

   </script> 
</body> 
</html>

Screenshot from the above example. The user will not be able to drag further south or east in this case:

Google Maps JavaScript API v3 Example: Limit Panning

Daniel Vassallo