[mapserver-users] Mapserver: set symbol on lines according to line features length

[Eichner, Andreas - SID]

AFAIK you need to preprocess your data and use CLASSes in your map file. Using OGR or a SQL database you might be able to do this on the fly within your DATA. For example, the command
  $ ogrinfo -dialect sqlite -sql "select st_length(geometry) > 10 as longenough from water_pipes" water_pipes.shp
creates a computed field containing 1 if the line geometry has a length greater than 10. You can then classify on this an apply a symbolization conditionally:

LAYER
  CLASS
    EXPRESSION "([longenough] != 0)"
    STYLE
      SYMBOL "wp_arrow"
      GAP -100
      COLOR 255 0 0
      OFFSET -5 -99
      SIZE 6
    END
  END
  CLASS
	# default style goes here
  END
END

I have not tested this but it might give you a hint how to accomplish it.

HTH


> -----Ursprüngliche Nachricht-----
> Von: mapserver-users [mailto:mapserver-users-bounces at lists.osgeo.org] Im
> Auftrag von wiltomap
> Gesendet: Montag, 30. November 2015 13:34
> An: mapserver-users at lists.osgeo.org
> Betreff: [mapserver-users] Mapserver: set symbol on lines according to
> line features length
> 
> I need to display arrows alongside to line features. Lines represent water
> pipes. The issue I'm facing is that lines are a concatenation of numerous
> line features of various lengths. Therefore, symbols are attached to every
> line, whatever its length. This makes symbols either overlaying or
> touching
> eachother (as in example below).
> 
> <http://osgeo-org.1560.x6.nabble.com/file/n5239136/wpp.png>
> 
> Inside my mapfile, I define the display rules of my symbols in the STYLE
> element:
> 
>     STYLE
>         SYMBOL "wp_arrow"
>         GAP -100
>         COLOR 255 0 0
>         OFFSET -5 -99
>         SIZE 6
>     END
> 
> I would like these rules to apply only to line features being more than 10
> meters long (or x map units).
> 
> Thanks in advance for help or any advice!
> 
> 
> Thomas
> 
> 
> 
> 
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