[Mapserver-users] GetLegendGraphic questions
Bart van den Eijnden
bartvde at xs4all.nl
Sat May 8 05:42:41 EDT 2004
Hi Assefa,
I got a response from Keith Pomakis (Cubewerx) on the wms-dev list and my
assumption was right. I also missed the labels next to the graphic in the
Mapserver implementation, but apparently the spec is not explicit about
this. But it would be nice to have it implemented like Cubewerx did.
Should I file an enhancement bug about this so we won't forget it?
This was his answer:
Yes, that's what it means. The title of each rule (or perhaps the name if
a title is not available) should perhaps be displayed as well so that the
rules can be distinguished.
Here's an working example of a GetLegendGraphic request that does this:
http://demo.cubewerx.com/demo/cubeserv/cubeserv.cgi?CONFIG=nrcan&SERVICE=WMS&VERSION=1.3.0&REQUEST=GetLegendGraphic&LAYER=ROUTE_L%3Anrcan&STYLE=Topographic&SCALE=125000&FORMAT=image%2Fpng&SLD=http%3A%2F%2Fdemo.cubewerx.com%2Fsld%2Fdemos%2Fntdb.xml
Best regards,
Bart
On Fri, 07 May 2004 21:15:52 +0200, Bart van den Eijnden
<bartvde at xs4all.nl> wrote:
> 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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>>
>>
>
>
>
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