[mapserver-users] Some Problems with WMS-GetLegendGraphic using agg and pixmaps

"Schönhammer, Herbert" Schoenhammer.Herbert at Regensburg.de
Wed May 7 00:26:52 PDT 2008


Hi list,

I have got some troubles generating legends with MS 5.0.2, used as a WMS-Server, using agg - driver and generating the legends from a pixmap with getlegendgraphic-request.

(See the mapfile snippets below !)

First Problem:
==========

Using gd the pixmap referenced by KEYIMAGE is scaled to the size defined by KEYSIZE.
Using agg the pixmap is NOT scaled. A part of the pixmap is shown as legend-graphic. This part is not scaled, size is 100% as in the original pixmap.

(My pixmap is larger than the size defined by KEYSIZE)


Second Problem:
============
Scaling the original pixmap DOES NOT really solve the problem, because:

Always only a part of the original pixmap is used for generating the legend-graphic: it is the part "cr" (center right) of the pixmap. So, if the original pixmap is scaled, only the "cr"-part is very small drawn in the legend-graphic.

The size of the part is correct after scaling the original pixmap, but always only a part of the original pixmap is shown.


Solution ?
=======

I think this is a bug.
But if you know a workaround, please let us know !

Thanks very much
Herbert




Mapfile Snippets:
============

 OUTPUTFORMAT
   #NAME png
   #DRIVER "GD/PNG"
   MIMETYPE "image/png"
   NAME 'AGG_Q'
   DRIVER AGG/PNG
   EXTENSION PNG
   IMAGEMODE RGBA 
   TRANSPARENT ON 
 END
  
LEGEND
  STATUS ON
  #KEYSIZE 55 40
  KEYSIZE 200 520
  KEYSPACING 10 5
  LABEL
      COLOR 0 0 0
      TYPE TRUETYPE
      FONT "verdana"
      SIZE 8
  END # END LABEL
  TRANSPARENT ON
  IMAGECOLOR 255 255 255
END   #LEGEND


....
LAYER ...
   CLASS
     NAME "Stadtplan farbig"
     KEYIMAGE "/data/raster/stadtplan/stadtplan_legende_hoch.png"
   END 
....
END # LAYER
.....

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