[mapserver-dev] MapServer legend functionality

Kralidis,Tom [Ontario] Tom.Kralidis at ec.gc.ca
Fri Jun 11 12:13:08 EDT 2010


Assefa: isn't this a GetMap request which outputs a legend image
instead?  I see similar logic.

I've seen CubeWerx use 'GetLegend', which displays a full legend, as a
VendorSpecificParameter in their WMS implementation, which I think is
very useful.

..Tom


> -----Original Message-----
> From: mapserver-dev-bounces at lists.osgeo.org 
> [mailto:mapserver-dev-bounces at lists.osgeo.org] On Behalf Of 
> Yewondwossen Assefa
> Sent: Friday, 11 June 2010 12:10
> To: Lime, Steve D (DNR)
> Cc: 'MapServer Dev Mailing List'
> Subject: Re: [mapserver-dev] MapServer legend functionality
> 
> 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.
> 
> regards
> 
> > 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
> http://www.dmsolutions.ca/
> 
> Phone: (613) 565-5056 (ext 14)
> Fax:   (613) 565-0925
> ----------------------------------------------------------------
> 
> 
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