11

How can one get the coordinates of a particular point on a map in OpenLayers?

Félix Adriyel Gagnon-Grenier
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cuser
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  • Do you mean getting the coordinates of the point where the user clicked? Or showing the coordinates of the cursor when moving it over the map? – amercader Jan 29 '10 at 10:01
  • yes, but I want to get all the coordinates of the previously marked points on the same map. Is it possible? I'm implementing a crime mapping system. For that I need that functionality. thanks. – cuser Feb 03 '10 at 14:48
  • What you mean as "previously marked points"? I think you need to be more specific and describe complete user's interaction flow, otherwise it will be difficult to help you. – mloskot Feb 03 '10 at 17:43

2 Answers2

33

Handle click event on map Click handler. Here is one of many sample codes you can find in OpenLayers mailing list archives:

map.events.register('click', map, handleMapClick);

function handleMapClick(e)
{
   var lonlat = map.getLonLatFromViewPortPx(e.xy);
   // use lonlat

   // If you are using OpenStreetMap (etc) tiles and want to convert back 
   // to gps coords add the following line :-
   // lonlat.transform( map.projection,map.displayProjection);

   // Longitude = lonlat.lon
   // Latitude  = lonlat.lat
}
mloskot
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5
<html>
 <head>
 <script src="http://openlayers.org/api/OpenLayers.js"></script>
 <script type="text/javascript"> 
    function init(){
      map = new OpenLayers.Map('map');
      base_layer = new OpenLayers.Layer.WMS( "OpenLayers WMS",
      "http://labs.metacarta.com/wms/vmap0", {layers: 'basic'} );
      map.addLayer(base_layer);
      map.zoomToMaxExtent();
      map.events.register('click', map, handleMapClick);
    } 

    function handleMapClick(evt)
    {
       var lonlat = map.getLonLatFromViewPortPx(evt.xy);
       // use lonlat
       alert(lonlat);
    } 
 </script>
 </head>
 <body onload="init()">
  Hello Map.<br />
 <div id="map"></div>
 </body>
</html>

@mloskot Your answer is great you had a mistake with the evt variable.

Just added the html markup to make it a working page.

MINDoSOFT
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