Grass GUI (was Re: [GRASS5] Problems with vector import, and a suggestion)

[Glynn Clements]

Radim Blazek wrote:

> > > Well, I like the idea of postscript.  The only drawback I see is that
> > > poor performance in redrawing are to be expected if you have a lot of
> > > lines to draw, and that you must include a postscript interpreter (or
> > > call an external one, which is also not very good for performances)
> >
> > Well, obviously the interpreter would be either Ghostscript (for
> > screen display, image creation, and printing to non-PostScript
> > printers), or the one which is built into a PostScript printer.
> >
> > As for performance, the overhead of sending PostScript to an external
> > process is trivial compared to the actual processing and rendering
> > (which occurs regardless of whether the interpreter is external).
> > Rendering complex geometry is expensive however you do it.
> 
> I share the fear of performance. I have tested the same vector:
> d.vect     2s
> gv           5s
> It is more than 100%. Do you have any trick how to get at least the
> same speed? 

It might be possible to modifiy the Ghostscript "x11" driver to detect
when the line width corresponds to 1 pixel and handle it as a special
case via XDrawLines().

Beyond that, if the performance of d.vect is paramount, there isn't
really any alternative to XDrawLines().

-- 
Glynn Clements <glynn.clements at virgin.net>