[Mapserver-users] Q: Dynamic Legends

[Ed McNierney]

Daniel -

I don't think that's quite the scenario being described.  I have a
similar problem that is not soluble AFAIK with current MapServer
technology.

I have a Land Use map that covers the state with polygons, each of which
is assigned one of 37 land use codes.  Any given map is unlikely to
display more than 3 or 4 different codes, but they all have a legend
with 37 entries in it, making the 3 that are actually ON the map hard to
find.

It's not a matter of selecting features by spatial scale, but by
selecting legend symbology based on data that is actually in the current
view frame.

	- Ed

Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
ed at topozone.com
(978) 251-4242  

-----Original Message-----
From: Martin, Daniel A [mailto:Daniel.A.Martin at erac.com] 
Sent: Thursday, January 29, 2004 4:03 PM
To: Jean-Henry Berevoescu
Cc: mapserver-users at lists.gis.umn.edu
Subject: RE: [Mapserver-users] Q: Dynamic Legends

I do exactly the same thing.  The way I do it, I have two layers
pointing at the same data.  One has only the highway class, and the
other has all street types.  But, here's the trick.  Name both layers
the SAME exact name.  Now, have the range set where the minscale of the
highway layer is the maxscale of the detailed street layer.

As the user zooms in and out, MapServer will naturally transition from
highways to detailed streets.  However, the legend will show exactly
what you are asking for.  And, by naming both layers the same name, the
status (on/off) will carry over as the user zooms.  If the highway layer
was on, the street layer will also be on when the user zooms in.

I know it may sound strange, but I promise it works beautifully.

-Dan

> -----Original Message-----
> From: Jean-Henry Berevoescu [mailto:bjh at globexplorer.com]
> Sent: Thursday, January 29, 2004 2:51 PM
> To: Martin, Daniel A
> Cc: mapserver-users at lists.gis.umn.edu
> Subject: Re: [Mapserver-users] Q: Dynamic Legends
> 
> 
> 
> No. I have, for example, one of the layers with a number of classes 
> (say, streets, with each type of street having its own class). In a 
> certain area, at a certain scale, one could get, for example, only 
> highways. What I want is to have the legend showing only the 
> symbols/definitions for what is actually in the map at a certain 
> moment.
> 
> Jean
> 
> 
> Martin, Daniel A wrote:
> 
> >Do you mean layers that are on, and within range, but are
> not visible
> >because of your current location?  I don't believe that is possible. 
> >However, the default is to hide layers that are not visible
> or have a
> >status of OFF.  However, if you have layers that have a status of 
> >DEFAULT, then those are going to show no matter what.
> >
> >Am I misunderstanding you?
> >
> >-Dan
> >
> >  
> >
> >>-----Original Message-----
> >>From: mapserver-users-admin at lists.gis.umn.edu
> >>[mailto:mapserver-users-admin at lists.gis.umn.edu] On Behalf Of 
> >>Jean-Henry Berevoescu
> >>Sent: Thursday, January 29, 2004 1:16 PM
> >>To: mdoggett at coas.oregonstate.edu
> >>Cc: mapserver-users at lists.gis.umn.edu
> >>Subject: Re: [Mapserver-users] Q: Dynamic Legends
> >>
> >>
> >>
> >>I tried that one and all the possible combinations (and their sum). 
> >>Nothing works.
> >>
> >>Thanks,
> >>Jean
> >>
> >>
> >>Matt Doggett wrote:
> >>
> >>    
> >>
> >>>I believe HTML legends will do the trick. In the
> >>>      
> >>>
> >>legend_template.html
> >>    
> >>
> >>>file you could specify [leg_class_html opt_flag=12] for
> example. see
> >>>the HTML legend How-To for more details about the opt_flag
> bit mask.
> >>>
> >>>http://mapserver.gis.umn.edu/doc40/html-legend-howto.html
> >>>
> >>>MD
> >>>
> >>> 
> >>>
> >>>      
> >>>
> >>>>-----Original Message-----
> >>>>From: mapserver-users-admin at lists.gis.umn.edu
> >>>>        
> >>>>
> >[mailto:mapserver-users-
> >  
> >
> >>>admin at lists.gis.umn.edu] On Behalf Of Jean-Henry Berevoescu
> >>>Sent: Wednesday, January 28, 2004 8:12 PM
> >>>To: mapserver-users at lists.gis.umn.edu
> >>>Subject: [Mapserver-users] Q: Dynamic Legends
> >>>
> >>>
> >>>Hi,
> >>>Is there a way to have the legend dynamically show only
> the classes
> >>>of
> >>>   
> >>>
> >>>      
> >>>
> >>a
> >> 
> >>
> >>    
> >>
> >>>layer actually
> >>>shown in a map (not the whole defined set in the mapfile)?
> >>>
> >>>Jean
> >>>
> >>>_______________________________________________
> >>>Mapserver-users mailing list Mapserver-users at lists.gis.umn.edu 
> >>>http://lists.gis.umn.edu/mailman/listinfo/mapserver-users
> >>>   
> >>>
> >>>      
> >>>
> >> 
> >>
> >>    
> >>
> >
> >_______________________________________________
> >Mapserver-users mailing list
> >Mapserver-users at lists.gis.umn.edu
> >http://lists.gis.umn.edu/mailman/listinfo/mapserver-users
> >
> >  
> >
> 
> 

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