Re: special behavior of postscript terminal? (again)

[Allin C. <cot...@wf...>]

On Thu, 23 Oct 2008, Ethan Merritt wrote:

> On Thursday 23 October 2008 12:30:21 Allin Cottrell wrote:
> > It seems to me that a nice solution would be if "set style line" 
> > were extended to include a "dashtype/dt" option, in the same way 
> > that pointtype can be selected independently of other features of 
> > the line.  
> 
> Isn't that what it does now?
> Each line type has an explicit dash pattern, selected by saying "lt N",
> analogous to selecting point type by saying "pt N".

Yes, but this depends on the terminal type, making it more or less 
impossible to produce a "portable" gnuplot command file which will 
produce similar effects (modulo inevitable differences in 
capabilities) across the various terminals.

I'm particularly interested in eps, pdf(cairo), png(cairo) and emf 
(on behalf of Windows users).  To get any dashes you have to set 
the "dashed" option for these terminals (except for postscript, 
which as I noted is exceptional in doing dashes by default).  But 
the "linetype" numbers in dashed mode produce different effects 
as noted below:

In postscript, dashed mode:

 solid lines: 1, 10, 19, 28
 regular dash: 2, 11, 20, 29
 short dash: 3, 12, 21, 30

in pngcairo, pdfcairo, dashed mode:

 solid lines: 1, 6, 11, 16, 21
 regular dash: 2, 7, 12, 17, 22
 short dash: 3, 8, 13, 18

in emf, dashed mode:

 solid lines: 1 to 15
 regular dash: 16 to 30
 short dash: 31 to 33

This is a total nightmare with regard to portability.  

Allin Cottrell