[OpenLayers-Users] removing a layer

[Puneet Kishor]

anyone, any suggestions? I am stuck on this for a couple of three days now. Briefly, I want to remove all the features from a vector layer so I can draw them anew on every "zoomend"

Many thanks in advance.


On Jan 20, 2012, at 11:45 AM, Puneet Kishor wrote:

> 
> 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
>>> Users at lists.osgeo.org
>>> http://lists.osgeo.org/mailman/listinfo/openlayers-users
>>> 
>> 
>> 
>> 
>> -- 
>> I.R
>