[mapserver-dev] MapServer legend functionality

Yewondwossen Assefa yassefa at dmsolutions.ca
Fri Jun 11 12:09:56 EDT 2010

On 11/06/2010 11:54 AM, Lime, Steve D (DNR) wrote:
> I think it would be a reasonable addition. Are you thinking about simply adding a visibility flag to a layer and flipping it
> if features are rendered? Often legend rendering is done separately from drawing, as two separate requests. Presumably you'd
> need a something like a fake draw map option in the legend code to make a drawing-like pass through the data. Could get expensive.
  Yes,  it could be an expensive operation to do a fake draw to get the 
legend. I am wondering if we could save something when a draw is done 
and retrieve it for the legend if it validates the current 
layers/extent  constraint.  Draw and legend are separate process but 
come usually one after the other so trying to take into account that 
fact might help.


> Steve
> -----Original Message-----
> From: mapserver-dev-bounces at lists.osgeo.org [mailto:mapserver-dev-bounces at lists.osgeo.org] On Behalf Of Yewondwossen Assefa
> Sent: Thursday, June 10, 2010 7:24 PM
> To: 'MapServer Dev Mailing List'
> Subject: [mapserver-dev] MapServer legend functionality
> Hi all,
>    I was looking into possible solutions re. MapServer legend and the
> possibility to only draw a legend (icon and text) based on the current
> visible features.
> The idea is to have this functionality exposed through interfaces such
> as OGC GetLegendGraphic that can provide the drawing "context" (such as
> layers, bbox ...). The idea is to allow users to have a reasonable
> legend based on what they are drawing.
> Do others run into this and see it as a useful addition?
> best regards,

Assefa Yewondwossen
Software Analyst

Email: yassefa at dmsolutions.ca

Phone: (613) 565-5056 (ext 14)
Fax:   (613) 565-0925

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