Hi,
I use always a baselayer like
var fakeLayer = new OpenLayers.Layer.Vector("Fake");
fakeLayer.isBaseLayer = true;
//fakeLayer.displayInLayerSwitcher = false;
,when i not use commercial layers.
Arnd
-----Ursprüngliche Nachricht-----
Von: openlayers-users-boun...@lists.osgeo.org
[mailto:openlayers-users-boun...@lists.osgeo.org] Im Auftrag von Puneet
Kishor
Gesendet: Sonntag, 28. November 2010 16:03
An: users
Betreff: [OpenLayers-Users] Re: map.removeLayer vs. map.destroy
I think I know what is going on, but I don't know why. Read on...
Puneet Kishor wrote:
> I have a map with lots of image layers (in addition to a few reference
> layers) for "scenario A". References to these image layers are stored
> in a global array, say "globLayers". I want to "reset" my map to
> depict another "scenario B". Right now I am removing all the layers
> for scenario A and then adding those for scenario B. It goes like so
>
> // Remove any old layers
> if (globLayers.length > 0) {
> for (var i = 0; i < globLayers.length; i++) {
> map.removeLayer(globLayers[i]);
> }
>
> // Reset globLayers
> globLayers = [];
> }
>
> /*
> Create new layers (various values that define the layer
> are calculated elsewhere)
> */
> for (var year = this.config.start_year; year <= end_year; year++) {
> var layer = new OpenLayers.Layer.Image(
> year,
> uri,
> new OpenLayers.Bounds(xmin, ymin, xmax, ymax),
> new OpenLayers.Size(img_w, img_h),
> {
> format: "image/gif",
> isBaseLayer: false,
> displayInLayerSwitcher: false,
> visibility: false
> }
> );
>
> // Register a moveend event that swaps the image on zoom level
> change
> layer.events.register("moveend", null, onzoom);
>
> globLayers.push(layer);
> }
>
> map.addLayers(globLayers);
>
> All of the above works just fine the first time. If I change my
> scenario, and load a new set of layers, I get the following error in
> Firebug in "OpenLayers.js (line 837)"
>
> layer is undefined
> if(this.allOverlays){layer.isBaseLayer=false;}
>
In my map options, I have allOverlays true. This is because I don't have an
explicit base layer. This works the first time I create the map and add
layers to it. However, if I remove the layers and add new layers back again,
the above `if(this.allOverlays){layer.isBaseLayer=false}` is triggered.
What can I do to avoid this?
> Two questions -- one, what is the reason for the error above? and two,
> should I be using map.removeLayers or map.destroy? I am assuming
> map.removeLayers because my map object is still needed, and is reused.
> In fact, I need it with all the other reference layers still visible.
>
> A corollary question -- under what scenarios does one use map.destroy?
> What is its usefulness?
>
> Puneet.
>
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