[OpenLayers-Users] Proportional Symbol Mapping

[Bjorn Sandvik]

Hi Matt,

I'm currently implementing your suggestions. I'm able to size the 
symbols as a function of the initial zoom level, but I can't figure out 
how to attach an event handler to the endzoom event. How can I add an 
event handler which makes a function call?

http://localhost/thematicmapping/experiments/openlayers/propsymbols.html
(the hover effect still needs some improvements).

Bjorn
http://blog.thematicmapping.org


mpriour wrote:
> Bjorn
> The correct way to handle this is to attach an event handler to the endzoom
> event.
> This event should manage the size of the symbols so that they are
> propotionally sized.
> Choose the zoom level at which the symbol renders at the right proportion,
> this will be your refernece zoom level. Then size the symbol propotionally
> the ratio of resolution @ current zoom level / resolution @ reference zoom
> level. Depending on the event firing order, you may also need to call
> redraw() on your vector layer.
> Matt
>
> Bjorn Sandvik wrote:
>   
>> Hi,
>>
>> I'm currently testing the capabilities of doing thematic mapping with 
>> OpenLayers.
>>
>> This is a proportional symbol map based on GeoJSON encoded data:
>> http://thematicmapping.org/experiments/openlayers_propsymb.htm
>>
>> My question: Is there a way to keep the relative size of the symbols 
>> when the users zoom in/out?
>> (symbols should keep their size relative to the size of the countries).
>>
>> Bjorn
>>
>> http://blog.thematicmapping.org
>>
>>
>>
>>
>> -- 
>> The University of Edinburgh is a charitable body, registered in
>> Scotland, with registration number SC005336.
>>
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>>
>>     
>
>   


-- 
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.