[OpenLayers-Users] Re: removing a layer

[Puneet Kishor]

On Jan 19, 2012, at 10:40 PM, Imran Rajjad wrote:

> I think the correct function is
> 
> layer.destroyFeatures();
> 
> which will empty the vector layer. You should not remove or re-initialize
> the layer. It makes sense to remove the layer from the map if you do not
> need it further.


Thanks, but nope, that does not work. here is my pseudocode triggered "onzoomend"

    var layer, features = [];
    
    function foo() {
        if (features.length > 0) {
            layer.destroyFeatures();
            features.length = 0;
        }
        else {
            layer = new OpenLayers.Layer.Vector("A vector layer");
            map.addLayer(layer);    
        }
        
        // add features and store in array
        for (var i = 0; i < n; i++) {
            var feature = createFeature();
            features.push(feature);    
        }
        
        layer.addFeatures(features);
    }
    
Everytime I zoom in or out, the above is triggered. features[] has n elements all the time showing that it is emptied and refilled, but the layer from previous iteration is still visible on the map. Any other suggestions?

This should not be so difficult but is confounding me. Maybe it needs its own special entry on a wiki or an FAQ.



> 
> regards,
> Imran
> On Fri, Jan 20, 2012 at 3:19 AM, Puneet Kishor <punk.kish at gmail.com> wrote:
> 
>> I am completely at my wits end. I am trying to check if a vector layer
>> exists, and if it does, I need to either completely remove it or remove all
>> the features from it (whichever is more efficient from the point of speed
>> and memory), and then redraw that layer. Have been trying all sorts of
>> permutations and combinations, but am just not successful.
>> 
>> My latest code attempt is below, and the original attempt is below that
>> from my OP.
>> 
>>   var arr = map.getLayersByName("Vector layer");
>> 
>>   if (arr.length) {
>>       //map.removeLayer(arr[0]);
>>       layer.removeAllFeatures();
>>   }
>>   else {
>>       layer = new OpenLayers.Layer.Vector("Vector layer", {styleMap:
>> myStyles});
>>   }
>> 
>> Neither `map.removeLayer(arr[0])` nor `layer.removeAllFeatures()` works.
>> 
>> Would appreciate suggestions.
>> 
>> On Jan 19, 2012, at 3:00 PM, Puneet Kishor wrote:
>> 
>>> I am trying to remove a layer with
>>> 
>>>   if (map.getLayerIndex(layer) > 0) {
>>>       map.removeLayer(layer);
>>>   }
>>> 
>>> but no joy. How can I remove a layer?
>>> 
>>> A bonus question: if I want to reconstruct a  vector layer on map
>> "zoomend", that is, redraw all the features on it so they are resized
>> accordingly, should I remove the layer (hence, the question above), or
>> simply remove all the features and redraw the features? If the latter, then
>> how?
>>> 
>>> Many thanks,
>>> 
>>> --
>>> Puneet Kishor
>> 
>> 
>> _______________________________________________
>> Users mailing list
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>> http://lists.osgeo.org/mailman/listinfo/openlayers-users
>> 
> 
> 
> 
> -- 
> I.R