[Fwd: Re: [UMN_MAPSERVER-DEV] single classed layers and GetLegendGraphic]

[Kralidis,Tom [Burlington]]

RULE makes me nervous because it's a MapServer specific which a WMS
client doesn't necessarily know at runtime.

This is what I propose:

- update GetLegendGraphic to:
 - print out legend icons of one layer as *just* an icon if there's only
one CLASS object
  - code change needed to handle this
 - print out legend icons of one layer with text of rule names if
there's more than one CLASS object
  - this is present behaviour -- no code change required
 - implement a VendorSpecific Capability called "GetLegend" which acts
like mode=legend, and prints out 'full' legends of multiple layers,
which includes titles for layers with icons

VERSION=1.1.1
SERVICE=WMS
REQUEST=GetLegend
FORMAT=<supported_image_format>
LAYERS=<layer_list>
STYLES=<style_list>

This way, one has the choice for both.  This eliminates the RULE
scenario from GetLegendGraphic.

Comments?

..Tom


> -----Original Message-----
> From: UMN MapServer Developers List 
> [mailto:MAPSERVER-DEV at LISTS.UMN.EDU] On Behalf Of Bart van den Eijnden
> Sent: Tuesday, 09 November, 2004 10:27
> To: MAPSERVER-DEV at LISTS.UMN.EDU
> Subject: [UMN_MAPSERVER-DEV] [Fwd: Re: [UMN_MAPSERVER-DEV] 
> single classed layers and GetLegendGraphic]
> 
> 
> Hi,
> 
> If I understand correctly, the problem is that 
> GetLegendGraphic for single class layers returns the text 
> next to the image if the Rule is not specified?
> 
> Maybe I am missing some part here in the discussion, but is a 
> GetStyles request not intended for getting the rule names?
> 
> >> We can use RULE=, however how would a WMS client know what the 
> >> rule/class names are?
> 
> BTW, I had not re-subsribed to the mapserver-dev list, I had 
> not realized it was also moved to the new listserv ...
> 
> Best regards,
> Bart
> 
> > 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.
> >  %2
>