[Mapserver-users] Q: Dynamic Legends

[Matt Doggett]

It seems like you could just do some kind of spatial query on your
"roads" (or land-use) layer based on the map extents. From the query
determine which classes are present, then modify the class layers
(dynamically w/ Perl/PHP mapscript of course) based on this information
before rendering the legend.

MD

>-----Original Message-----
>From: mapserver-users-admin at lists.gis.umn.edu [mailto:mapserver-users-
>admin at lists.gis.umn.edu] On Behalf Of Ed McNierney
>Sent: Thursday, January 29, 2004 2:16 PM
>To: Martin, Daniel A; Jean-Henry Berevoescu
>Cc: mapserver-users at lists.gis.umn.edu
>Subject: RE: [Mapserver-users] Q: Dynamic Legends
>
>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
>> >>>
>> >>>
>> >>>
>> >>>
>> >>
>> >>
>> >>
>> >>
>> >
>> >_______________________________________________
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>> >
>> >
>> >
>>
>>
>
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