[OpenLayers-Users] Fwd: Problem with GML features

[Tim Schaub]

Hey Dmitri-

Dmitri Mizerkin wrote:
> Hi!
> 
> I haven't got any reaction to my previous mail, so I'm trying to point 
> your attention to my problem again in this follow-up.
> The problem is: after loading a GML layer the features collection of the 
> layer stays empty (at least for some time), which means that there's no 
> way to handle those in the loadend-event of the layer. Is there another 
> event, which is raised after the features collection of the loaded layer 
> is initialized? Is there any rational workaround?

You're right.  There is no good way to do what you want right now.  I 
assume you're talking about the WFS layer in vector mode (as opposed to 
marker mode).  When the tile for this layer is drawn a WFS request is 
made asynchronously - when this request returns, the GML is parsed and 
added to your layer.  As each feature is added to your layer, the 
optional onFeatureInsert property of your layer (a function) is called. 
  This is not handy if you want to know when the features are done being 
added.

I thought there was a ticket out there already for this.  I'll check - 
and add one if not.

I'm hoping to do some work on the WFS layer in the near future.  This 
and other issues will likely get addressed then.

Tim


> 
> Cheers,
> Dmitri Mizerkin
> 
> ---------- Forwarded message ----------
> From: *Dmitri Mizerkin* <eisberg at gmail.com <mailto:eisberg at gmail.com>>
> Date: 05.07.2007 10:33
> Subject: Problem with GML features
> To: users at openlayers.org <mailto:users at openlayers.org>
> 
> Hello everybody!
> 
> I'm experiencing problems with handling the features of a GML layer, 
> which is loaded when the page is opened. The problem is that after the 
> 'loanend' event is raised, the features-property of the layer stays 
> empty for some more time, so there is no way to examine the features in 
> this handler. In my case I need to extract the bounds-properties of the 
> features to construct an common bounds-object for zooming (the action 
> should simulate feature selection and zooming to the selection).
> 
> Any ideas, how this could work?
> 
> Here's my code snapshot:
> 
> function SelectFeature() {
>   var layer = GetLayerByName(FEATURE_LAYER); //returns a MapServer layer 
> to send a request on
>   if (layer == null)
>     return;
>   var selection_url = CreateWFSGetFeatureRequest(layer, FIELD_NAME, 
> FIELD_VALUE); //creates a WFS GetFeature-request
>   if ((selection != null)&&(selection.map != null)) {
>     OLMap.removeLayer (selection);
>     selection = null; 
>   }
>   selection = new OpenLayers.Layer.GML("Selected Objects", selection_url);
>   OLMap.addLayer(selection);
>   selection.displayInLayerChooser = false;
>   selection.events.register ("loadend", selection, ZoomToSelection);
>   selection.events.triggerEvent("loadend");
> }
> 
> function ZoomToSelection() {
>   var bounds = ComputeSelectionBounds();
>   if (bounds == null)
>     return;
>   OLMap.zoomToExtent(bounds);
> }
> 
> Thanks in advance!
> 
> -- 
> Regards,
> Dmitri
> 
> -- 
> Gruß,
> Dmitri
> 
> 
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