single classed layers and GetLegendGraphic

[Yewondwossen Assefa]

Kralidis,Tom [Burlington] wrote:

>>-----Original Message-----
>>From: Yewondwossen Assefa [mailto:assefa at dmsolutions.ca]
>>Sent: Monday, 08 November, 2004 10:30
>>To: Kralidis,Tom [Burlington]
>>Cc: MAPSERVER-DEV at LISTS.UMN.EDU
>>Subject: Re: [UMN_MAPSERVER-DEV] single classed layers and
>>GetLegendGraphic
>>
>>
>>Is it possible for you to use the RULE parameter (set to the
>>class name
>>) ? That should retun only the icon for the class.
>>If not, I am not sure what the best solution is. Maybe add a
>>support to
>>a vendor specific request parameter that alaways return an
>>icon for the
>>first class. I personnaly prefer this way rather than having
>>a diffrent
>>behaviour when there is one or more than one classes. Comments ?
>>
>
>
> We can use RULE=, however how would a WMS client know what the
> rule/class names are?
>
> I have received some other responses which favour this approach because
> one can get a 'full' legend without the need to print out text, as it's
> handled in the output graphic.  This makes sense in this context.
>
> As a result, what do people think about:
>
> - making GetLegendGraphic always return icon ONLY for single-class
> layers, full for multiple classes (as per now)
> - adding in VendorSpecificCapabilities called "GetLegend" which would
> return a 'full' legend, titles and all for multiple layers, so someone
> can get a single legend icon for multiple WMS layers from the same WMS?
> We could also extend so that such a request can also ingest a Web Map
> Context Document and output a single legend graphic.
>
> Comments?
>

I waited a bit for others to respond.

I personally like the idea of giving the control to the user to output
full legend or icons based on a specific VendorSpecificCapabilities.
   Saying that the implementation of the GetlegendGraphic has been
discussed lengthly and we ended up with what we have now. What you are
proposing is a behaviour change just before a release. It is not too
late to make this kind of change and if it is better we certainly should
do it before the release (since it is the first relase of Mapserver with
the GetlegnedGraphic), but others involved in it should certainly
approve this.  I have  cc'd Bart and Valik who were invloved in the
GetLegend development/dicsussion in case they are not the the dev list.

Later,






--
----------------------------------------------------------------
Assefa Yewondwossen
Software Analyst

Email: assefa at dmsolutions.ca
http://www.dmsolutions.ca/

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