[OpenLayers-Dev] cartodiagrams

[Tim Schaub]

Hey-

Per-Olof Norén wrote:
> Hi,
> 
> Pavel Simon skrev:
>> Hi everyone,
>>
>>  I plan to work on a project about adding cartodiagrams to OpenLayers.
>>  So I want to ask, if someone in your group works on a similar project?
>>  If the answer is yes, could you write me about it?
>>
>>   
> If you are using geoserver as backend, then maybe this nice tutorial 
> might be of interest:
> http://blog.geoserver.org/2008/12/08/dynamic-symbolizers-part-1/
> 
> I've tried using using google chart API to add pie charts to a dataset 
> of swedish election results from 2006. The charts is placed on each 
> election district's polygon centroid.
> 
> I uploaded an example image here:
> http://images.upload2world.com/get-3-2009-upload2world_com_ghdps.png
> 

Another example using the Google Chart API:
http://blog.thematicmapping.org/2008/04/openlayers-and-google-chart-mashup.html

If your symbols are generated on the server, there's no real work to do 
in OpenLayers (assuming values based on feature attributes are all that 
are needed).  If you don't have an image (or chart or cartodiagram or 
whatever) url in your feature attributes, you can generate a url for a 
symbolizer's externalGraphic property with a style's context property.

See http://openlayers.org/dev/examples/styles-context.html for an example.

Tim

> OpenLayers is then used as a client against geoserver WMS.
> 
> Regards
> Per-Olof
> 
> 
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-- 
Tim Schaub
OpenGeo - http://opengeo.org
Expert service straight from the developers.