[OpenLayers-Users] How to stop registering events

[Max Stephan]

Ok, thanks. Now the unregistering works and the function that gets called
when the event was triggered only runs once. But another problem appeared.
The layer that contains the features I want to select is shown or hidden
depending on the resolution. For this reason I need to query the WFS-Server
if the searched feature is not in the current bounds or the layer is not
shown at all because of the resolution of the map. By doing this I can get
the bounds of the searched feature, zoom to it and then wait for the layer
that contains features of this featuretype to load. When it has finished
loading I can select the feature.

So, what´s the problem now? If the feature is already in the layer so that
no extra WFS-query has to be performed selecting it works flawlessly. I can
click out of this feature and it get´s unselected etc.
On the other hand, when an extra-WFS-request has to be performed the feature
also gets selected and the map zooms to it. BUT: It leads to a very strange
behavior:
1. when clicking outside the feature it doesn´t get unselected. It only
get´s unselected when clicking on another feature
2. some features that I select after this immediately get unselected again
after they´ve got marked as selected and the map zoomed to them

This behaviour persists so I guess something got corrupted in the script. It
also is existent when I´m only zooming to the queried feature (without
selecting it).

If needed I can give you the URL to the application via private mail but I
can´t make it public.

Here´s the code segment with comments:
function zoomToTrigger(evt){
	aufrufCounter ++; //just for debugging
	document.getElementById('selectStatus').innerHTML+="zoomTrigger
ausgef&uuml;hrt;<br>";
	// unregister the loadend event

wfsLiegenschaften.events.unregister('loadend',wfsLiegenschaften,zoomToTrigger);
	//
	zoomToLiegenschaft(globalID);
};

/* Given an id this method first calls the searchFeature-method to find out
if this feature
is already loaded into the layer. This is necessary because the layer is
only visible in an
given resolution-interval. If that´s not the case (false returned) it calls
the getFeatureBounds-method
which performs a wfs-filter-request, calculates the bounds for the feature,
zooms to this extend and waits
for the layer to load and after that event was triggerd calls the
zoomToTrigger-method which
unregister the loadend-event and recursively calls the
zoomToLiegenschaft-method */
function zoomToLiegenschaft(id){
	// remembers the id that was searched for in a global attribute
	globalID = id;
	searchResult = searchFeature(wfsLiegenschaften,id);

	if(searchResult==false){
		getFeatureBounds('jos:Liegenschaften','FlaechenID',id);
	}
};

/* finds out if a feature with the given id exists in the layer. If it´s the
case
this feature gets selected (selecting it automatically zooms to it´s bounds)
and true is
returned. If the feature is not available "false" is returned. */
function searchFeature(layer,id){
	for(var feat in layer.features){
		if(layer.features[feat].attributes.FlaechenID == id){
			selectControl.unselectAll();
			selectControl.select(layer.features[feat]);
			return true;
		}
	}
	return false;
};

function getFeatureBounds(layer,filterAttribute,filterValue){
	var params = new Array();
	// Schreiben der gesuchten ID in globale Variable, damit sie für andere
Methoden zur Verfügung steht
	temp_filterValue = filterValue;
	temp_layer = layer;
	params[0] = "typename="+layer;
	params[1] = "FILTER=<Filter>";
	params[1] += "<PropertyIsEqualTo>";
	params[1] += "<PropertyName>" + filterAttribute + "</PropertyName>";
	params[1] += "<Literal>" + filterValue + "</Literal>";
	params[1] += "</PropertyIsEqualTo>";
	params[1] += "</Filter>";
	try{

OpenLayers.loadURL('//GEOSERVER-Location//',('?srs=EPSG:31468&SERVICE=WFS&VERSION=1.0.0&REQUEST=GetFeature&'+params[0]+'&'+params[1]),readGML,readGML,loadFailure);
	}
	catch(err){
		showError("@loadGML: Fehler beim Laden der GML (" + err.message + ")");
	}
}

function loadFailure(response){
	showError("Fehler beim Laden der GML (" + err.message +")");
}

function readGML(response){
	// Parse the GML
	gml = new OpenLayers.Format.GML();
	featureList = gml.read(response.responseText);
	// Get the Bounds for the received features
	featureBoundsList = new Array();
	for(var features in featureList){
		featureBoundsList[features] = featureList[features].geometry.getBounds();
	}
	// calculate the Bounds for the feature/features
	totalBounds = 0;
	for(var bounds in featureBoundsList){
		if(totalBounds == 0){totalBounds = featureBoundsList[bounds];}
		else{totalBounds.extend(featureBoundsList[bounds]);}
	}
	// zoom to the calculated bounds
	map.zoomToExtent(totalBounds);
	// register when the layer that contains the features finished loading and
call the zoomToTrigger-method

wfsLiegenschaften.events.register('loadend',wfsLiegenschaften,zoomToTrigger);
}

Eric Lemoine-2-2 wrote:
> 
> On Thu, Oct 29, 2009 at 3:17 PM, Max Stephan <x.zam at gmx.net> wrote:
>>
>> Hi Eric,
>>
>> thanks for your help but I don't get the idea what your code is doing.
>> Could
>> you explain it?
> 
> it was just to show you that unregister works as expected.
> 
>> Furthermore what is the unregister function in general
>> exactly doing. Am I right in thinking it stops the previous defined
>> registering of an event or is it doing something else?
> 
> it unregisters an event listener, it doesn't stop the event from being
> triggered.
> 
> 
> -- 
> Eric Lemoine
> 
> Camptocamp France SAS
> Savoie Technolac, BP 352
> 73377 Le Bourget du Lac, Cedex
> 
> Tel : 00 33 4 79 44 44 96
> Mail : eric.lemoine at camptocamp.com
> http://www.camptocamp.com
> _______________________________________________
> Users mailing list
> Users at openlayers.org
> http://openlayers.org/mailman/listinfo/users
> 
> 

-- 
View this message in context: http://n2.nabble.com/How-to-stop-registering-events-tp3911670p3918351.html
Sent from the OpenLayers Users mailing list archive at Nabble.com.