[OpenLayers-Users] Re: Questions about Filtering WFS

[Phil Scadden]

On 8/12/2011 6:02 p.m., Diego M. wrote:
>
> *Strongly consider using WMS to display and WFS to query instead. *
> is there any example to explane how to do that ?
Add the layer to the map as a WMS layer styled with a SLD. A simple 
query (click on the object) can be done then wmsgetfeature (see OL 
examples). For polygon, within-radius-of-click, text search,
you create a wfsProtocol object, set the appropriate filter (polygon, 
dwithin or a logically query depending on application) and do  a read on 
the protocol, with a call back to process the result.

Look at examples and search mailing list for wfsprotocol.

>
> *You need to convert the distance into native projection (application
> knowledge). *
> also how i can do that ?
>
> I'm really stuck here.
Something like:
pt1 = e.features.geometry; // assuming you are doing this a registered event
pt2 = pt1.clone();
pt2.x += myDistance // in display projection units)
pt1.transform(displayprojection, nativeproject);
pt2.trasnform(displayprojection, nativeproject);
myDistance = Math.abs(pt1.x-pt2.x);

However, you need to know what native projection is. Get that from the 
server.


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