[GRASS-dev] Getting a dotted line in ps.map - Style mechanism

[Hamish]

Alessandro Frigeri wrote:
> I wonder how can I obtain a dotted linestyle with ps.map.  
> Using the style parameter with a 1010 value, I only get a dashed
> line.  What controls the length of the dashes?  From the ps.map
> man-page (6.3.0) I really did not fully understand the mechanism of
> the 'style' parameter.

sorry, the documentation did not match the code very well.
(ie either the docs or the code is buggy, I am not really sure which)

try like:

# spearfish dataset
ps.map out=test.ps << EOF
vlines roads
  style 011111111
  where label ~ 'highway'
  width 0.5
  label Highways
  end
end
EOF


The first block is draw, the second block is don't draw. So with a single
zero followed by lots of ones it draws a little then skips a lot making a
dotted line.


> Moreover, the example of the style parameter reported in the vlines
> section of the manual with '0-9' value, rises up an error:
> 
> ERROR: style 0-9 : illegal line style (vlines)

"0-9" just means some value in the range of zero to nine. Forget about
that, just use 0s and 1s. Any non-zero number will be treated as a one.


I've just updated the man page in SVN to make things clearer:
  http://trac.osgeo.org/grass/changeset/32537

although I am not sure if the current way is as-intended or a bug.
intuitively I'd guess that 0 should be don't draw and 1 should be draw,
but alas..


devels see also the PostScript 'setdash' command usage and new debug messages:
  http://www.capcode.de/help/setdash


Hamish