Re: Enhanced Mode and Postscript (again)

[Ethan M. <merritt@u.washington.edu>]

On Thursday 24 July 2008 13:48:52 Philipp K. Janert wrote:
> 
> I think there might be a problem with 
> enhanced mode in Postscript and the 
> overlay/lifting operator ~
> 
> The following commands produce good
> results with the enhanced wxt terminal,
> but not with the enhanced postscript
> terminal:
> 
> set label 1 "~a{.7{/*.7\\~}}" at 0,0
> set label 2 "~a{.7{/*.8=}}" at .5,0
> set label 3 "~a{.6{/*1-}}" at -.5,0
> plot [-1:1][-1:1] 2
> 
> The problem appears to be that the second
> character is not properly lifted as it should be,
> when using Postscript.
> 
> Is this a known issue?

Yes. But it's more fundamental that that.
Basically you cannot nest curly braces inside the overprint
operator.  If you remove the nested braces, everything works
as expected (I think :-).

 set label 1 "~a{.7\\~}" at 0,0
 set label 2 "~a{.7=}" at .5,0
 set label 3 "~a{.6-}" at -.5,0

The overprint operator really does not work very well.
I have a list of problems from various drivers.  If you can,
it is better to use either the @ operator instead, or in a case
like your example simply use the extended character set to
draw the accented character as a single glyph.

For instance, your first label above could be

  set label 1 "@^\\~_a"
or (much better)
  set encoding iso_8859_15
  set label 1 "{\343}"

This all works better in the gd or wxt terminals than in PostScript, however.

	Ethan




> 
> Also, and I am not sure whether I consider
> this a bug or a feature, when making the
> overlayed character very large, it affects
> the absolute position of the first character
> in the enhanced wxt terminal.
> 
> (My guess is that gnuplot uses the combined
> bounding box of both characters to position
> the entire label. From a user perspective, I
> would have expected that only the non-lifted
> character determines the position.)
> 
> 
> 
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-- 
Ethan A Merritt