[Mapserver-users] GetLegendGraphic questions
Bart van den Eijnden
bartvde at xs4all.nl
Fri May 7 15:15:52 EDT 2004
Hi Assefa,
my interpretation of the OGC spec is different.
If you do not provide a rule in the request, I think the SLD WMS should
produce a graphic for each Rule (in Mapserver terms CLASS) combined in one
image. I don't think it is the intention of the spec to draw them all on
top of each other though ....
"to produce a graphic that is representative of all of the rules of the
style." I don't think an image which draws them all on top of each other
is representative of all the rules of the style. But I must agree the spec
is a bit vague on this subject.
I will ask on the wms-dev list.
Best regards,
Bart
On Fri, 07 May 2004 15:02:46 -0400, Yewondwossen Assefa
<assefa at dmsolutions.ca> wrote:
> Hi There,
>
> From reading the specs, my interpretation of the GetLegendGraphic is
> that It is supposed to return one image (icon) representing the styles
> used to render a particular layer. I don't think It is meant to return
> an image containing all the icons for every class that is found in the
> layer. (If It was implemented that way, It would be impossible for a
> user to specify adequattly the the width/heigh of the image since he
> does not really know how many classes are in the layer).
>
> The other note is that all the classes are drawn on top of each other.
> Here again the implmentation is based on my interpretaion of the specs
> (sld1.0 section 12 Map Legends) where the mention the following for the
> RULE parameter of the GetLegendGraphic request:
>
> "Rule of style to produce legend graphic for, if applicable. In the
> case that a style has multiple rules but no specific rule is selected,
> then the map server is obligated to produce a graphic that is
> representative of all of the rules of the style."
>
> Since we do not support RULE for now, drawing all the classes seemed
> to be the closest interpretation. When/If RULE is supported, the user
> will have the option to use it to draw a particular class.
>
>
> Later,
>
>
>
>
> Emil Zegers wrote:
>
>> Hello Bart,
>>
>> Don't know if this is the cause but when you look in maplegend.c
>> msDrawLegendIcon is called in the else part if class is NULL (if class
>> is NULL all classes should be drawn):
>>
>> // Call drawLegendIcon with destination (0, 0)
>> // Return an empty image if lp==NULL || class=NULL //(If class is
>> NULL draw the legend for all classes. Modifications done
>> // Fev 2004 by AY)
>> if (lp) {
>> msClearLayerPenValues(lp); // just in case the mapfile has already
>> been processed
>> if (class) {
>> msDrawLegendIcon(map, lp, class, width, height, image->img.gd, 0,
>> 0);
>> }
>> else {
>> for (i=0; i<lp->numclasses; i++) {
>> msDrawLegendIcon(map, lp, &lp->class[i], width, height,
>> image->img.gd, 0, 0);
>> }
>> }
>> }
>>
>> But doesn't it clip every image on top on the former one like this with
>> dstX en dstY set to 0?
>>
>> Regards,
>>
>> Emil Zegers
>>
>>
>>
>>>>> <bartvde at xs4all.nl> 05/07/04 01:38pm >>>
>>
>> Hi list,
>>
>> I have some questions about the GetLegendGraphic operation in Mapserver.
>>
>> I have a layer in my MAP file which has 5 classes, but when performing a
>> GetLegendGraphic request I only get an image of the last class defined.
>> Should I not get an image of all classes?
>>
>> Also, how do you get the "text labels" for the specific classes, e.g.
>> "0-20%" next to the symbols?
>>
>> Maybe I am missing something in my LAYER definition?
>>
>> This is the request I am using:
>> http://myserver/cgi-bin/mapserv.exe?map=/ms4w/apps/zulte/map/zulte_server..map&layer=kwelder_2000&version=1.1.1&request=GetLegendGraphic&format=image/png
>> This is my LAYER definition:
>>
>> LAYER
>>
>> METADATA
>> WMS_TITLE "2000_kwelder"
>> WFS_TITLE "2000_kwelder"
>> WMS_ABSTRACT "2000_kwelder"
>> WMS_SRS "epsg:28992"
>> END
>> NAME "kwelder_2000"
>> CONNECTIONTYPE OGR
>> TILEINDEX "2000.shp"
>>
>> SIZEUNITS PIXELS
>> STATUS ON
>> TOLERANCE 3
>> TOLERANCEUNITS PIXELS
>> TYPE POLYGON
>> DUMP TRUE
>> TEMPLATE "blank.html"
>> UNITS METERS
>> CLASSITEM "Kwelder_to"
>> CLASS
>> EXPRESSION (([Kwelder_to] > 0) AND ([Kwelder_to] <= 20))
>> NAME "0-20%"
>> COLOR 254 255 212
>> END
>> CLASS
>> EXPRESSION (([Kwelder_to] > 20) AND ([Kwelder_to] <= 40))
>> NAME "21-40%"
>> COLOR 255 218 143
>> END
>> CLASS
>> EXPRESSION (([Kwelder_to] > 40) AND ([Kwelder_to] <= 60))
>> NAME "41-60%"
>> COLOR 255 151 41
>> END
>> CLASS
>> EXPRESSION (([Kwelder_to] > 60) AND ([Kwelder_to] <= 80))
>> NAME "61-80%"
>> COLOR 217 95 13
>> END
>> CLASS
>> EXPRESSION (([Kwelder_to] > 80) AND ([Kwelder_to] <= 100))
>> NAME "81-100%"
>> COLOR 153 54 5
>> END
>> END
>>
>> Thanks in advance for any info on this subject.
>>
>> Best regards,
>> Bart
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