<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
  <meta content="text/html;charset=UTF-8" http-equiv="Content-Type">
</head>
<body bgcolor="#ffffff" text="#000000">
Hello Jay,<br>
<br>
Thanks for your help. I ended up doing:<br>
<br>
markers.events.on({ "featureselected": onMarkerSelect,
"featureunselected": onMarkerUnselect, <b>"visibilitychanged":
onMarkerToggle</b> });<br>
<br>
     function onMarkerToggle(event)
{                                                                                                                                             
<br>
        //ask for this layers refresh if visibility becomes
true                                                                                                                 
<br>
        if(markers.visibility ==
true){                                                                                                                                          
<br>
//          alert("requesting marker
refresh");                                                                                                                                  
<br>
            updateActiveAlarms(); //this refreshes the layer<br>
       
}                                                                                                                                                                        
<br>
    }                                         <br>
<br>
It works perfectly. Thanks again,<br>
Adrian<br>
<br>
Jay Douillard wrote:
<blockquote
 cite="mid:10988451.80491247678255022.JavaMail.root@verrazzano"
 type="cite">
  <pre wrap="">Adrian,

You need to register events to fire when want refreshing to occur.
You can use the visibility property of a layer to test if it is visible and only refresh those layers that are.
<a class="moz-txt-link-freetext" href="http://dev.openlayers.org/releases/OpenLayers-2.8/doc/apidocs/files/OpenLayers/Layer-js.html#OpenLayers.Layer.visibility">http://dev.openlayers.org/releases/OpenLayers-2.8/doc/apidocs/files/OpenLayers/Layer-js.html#OpenLayers.Layer.visibility</a>

<a class="moz-txt-link-freetext" href="http://dev.openlayers.org/apidocs/files/OpenLayers/Events-js.html">http://dev.openlayers.org/apidocs/files/OpenLayers/Events-js.html</a>
----
Jay 


----- Original Message -----
From: "Adrian Popa" <a class="moz-txt-link-rfc2396E" href="mailto:adrian_gh.popa@romtelecom.ro">&lt;adrian_gh.popa@romtelecom.ro&gt;</a>
To: <a class="moz-txt-link-abbreviated" href="mailto:users@openlayers.org">users@openlayers.org</a>
Sent: Tuesday, July 14, 2009 11:27:17 PM GMT -08:00 US/Canada Pacific
Subject: [OpenLayers-Users] Overriding overlay select to force a reload of the toggled layer

Hi everybody,

I have several overlay vector layers that get their data in KML format 
from some server-side scripts. The data is highly dynamic, so it needs 
to be refreshed constantly (this is solved). The problem appears if only 
one overlay layer is selected (visible), I need to refresh all overlay 
layers so that if the user toggles another overlay, he will have the 
most recent data. I would like to reduce the overhead on the server and 
client side and only refresh the visible overlay layers, and to force a 
refresh of a layer whenever the user makes it visible. For this I would 
have to override the function that runs when a layer is selected in the 
layer switcher and call another refresh function before the layer is 
made visible. Can anyone point me in the right direction?

P.S. I would like to do this without editing the openlayers code; 
instead I would like to override/overload the function for my objects only.

Thanks,
Adrian

_______________________________________________
Users mailing list
<a class="moz-txt-link-abbreviated" href="mailto:Users@openlayers.org">Users@openlayers.org</a>
<a class="moz-txt-link-freetext" href="http://openlayers.org/mailman/listinfo/users">http://openlayers.org/mailman/listinfo/users</a>

  </pre>
</blockquote>
<br>
</body>
</html>