[Chameleon] querytool and radius

[Bart van den Eijnden]

Hi Paul,

thanks for the reply. I knew about the buffer option in queryByPoint from dealing with Mapserver WFS lately.

First I thought this would require changes to be made to the Chameleon core since executePointQuery in map_query.php does not take a radius/buffer argument. 

But looking a bit further even buffers in meters would be possible without changes to the Chameleon core by setting TOLERANCEITEMS to METERS on the LAYER and a TOLERANCE on the LAYER object using PHP/Mapscript.

Maybe I'll try to create this in the next weeks (for local layers).

Best regards,
Bart

Bart van den Eijnden
Syncera-ITSolutions
Postbus 270
2600 AG  DELFT

tel.nr.: 015-7512436
email: BEN at Syncera-ITSolutions.nl

>>> Paul Spencer <pspencer at dmsolutions.ca> 05/13/05 03:50pm >>>
Bart,

the radius is actually not used except in WMS queries and it is a 
vendor-specific-extension of WMS used by CubeSERV web servers ... I 
think there was a plan to add it to MapServer but I don't know if it 
ever happened.  Also, the radius is in pixels, not geographic units.

I'm not sure if it is possible to do this out of the box with mapserver 
queries, but it would be a neat addition to Chameleon.  I just checked 
the php/mapscript docs and it seems that only query by point supports a 
buffer and it is in pixels.  Specifying a buffer in other coordinates 
would require a conversion to pixels at the current scale with an 
associated loss of precision

The real solution to this will come with GEOS integration.

Paul

Bart van den Eijnden wrote:
> Hi list,
> 
> does Chameleon have functionality for the following? I see there is a radius attribute for the query tool which can be set by the developer, but can it be set by the user?
> 
> Can a user specify a radius in meters in an input field, and then when he clicks in the map, similar DHTML functionality to the ROICircle tool draws the circle on the map. The query is then performed within this radius. If he resets the radius, and clicks again in the map, no circle is drawn.
> 
> If there is no functionality for this, how could it be created best?
> 
> Best regards,
> Bart
> 
> Bart van den Eijnden
> Syncera-ITSolutions
> Postbus 270
> 2600 AG  DELFT
> 
> tel.nr.: 015-7512436
> email: BEN at Syncera-ITSolutions.nl 
> 
> 
> _______________________________________________
> Chameleon mailing list
> Chameleon at lists.maptools.org 
> http://lists.maptools.org/mailman/listinfo/chameleon 
> 

-- 
+-----------------------------------------------------------------+
|Paul Spencer                           pspencer at dmsolutions.ca   |
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|Applications & Software Development                              |
|DM Solutions Group Inc                 http://www.dmsolutions.ca/| 
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