[OpenLayers-Users] Markers' events memory leak?

[Donal]

I hope that some might find this useful.

I found the following function at http://dev.rubyonrails.org/ticket/5198

// Remove all event handlers from an element
  stopObservingElement: function (element) {
    if (! Event.observers) return;
      for (var i = 0; i < Event.observers.length; ) {
        if (element == Event.observers[i][0]) {
          Event.stopObserving.apply (this, Event.observers[i]);
          Event.observers.splice (i, 1);
        }
        else
          i++;
      }
   }

I added this function to the OpenLayers.Event class.

I now can call OpenLayers.Event.stopObservingElement(this.imageDiv); in the
icon destroy() method and the memory leak is kept in check.

Cheers,

Donal




Donal wrote:
> 
> Hello,
> 
> I have a GeoRSS layer which displays a number of icons equal to the value
> of a select box e.g. 10,25,50,100.
> When the select box changes value, the GeoRSS layer is destroyed and a new
> layer is displayed with the new number of icons. I notice in IE 6 that the
> memory used steadily increases as I repeatedly change (up and down)  the
> value in the select box.
> 
> I see that when a marker is initialized,  BROWSER_EVENTS are attached to
> the marker's element (this.icon.imageDiv)  with a call to
> OpenLayers.Event.observe(element,eventType,this.handleBrowserEvent.bindAsEventListener(this));
> in Events.js attachToElement() function.
> 
> If I comment out the call to attachToElement, the memory used stays fairly
> constant as I change the select box value (but obviously my markers have
> no events associated with them which isn't much use). This suggests to me
> that events not being detached/removed properly are the cause of the leak.
> 
> So I want to try something like 
> 
> OpenLayers.Event.stopObserving(this.icon.imageDiv, "mouseover", observer);
> 
> for each of the BROWSER_EVENTS as the markers are destroyed but I am not
> sure what I should put as the value for observer.
> 
> I have tried 
> 
> adding the following propeties to the Events object
> 
> this.obs_handles = new Object();
> this.obs_handles[element] = new Array();
> 
> and then in attachToElement doing
> 
> this.obs_handles[element][eventType] =
> this.handleBrowserEvent.bindAsEventListener(this);
> OpenLayers.Event.observe(element, eventType,
> this.obs_handles[element][eventType]);
> 
> and then in Markers.destroy() adding
> 	
> OpenLayers.Event.stopObserving(this.icon.imageDiv,"mouseover",this.events.obs_handles[this.icon.imageDiv]["mouseover"]);
> OpenLayers.Event.stopObserving(this.icon.imageDiv,"mouseout",this.events.obs_handles[this.icon.imageDiv]["mouseout"]);
> OpenLayers.Event.stopObserving(this.icon.imageDiv,"mousedown",this.events.obs_handles[this.icon.imageDiv]["mousedown"]);
> etc;
> 
> this.events.obs_handles[this.icon.imageDiv] = null;
> this.events.obs_handles = null;
> 
> but this has no effect.
> 
> Am I barking up the wrong tree? Any help/advice will be gratefully
> received.
> 
> Thanks,
> 
> Donal
> 
> 

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