Re: Bug Report and Enhanced text question

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

On Tuesday 04 April 2006 12:25 pm, Bastian Maerkisch wrote:
> > 
> >> The usual enhanced_recursion calls will need feedback about the text 
> >> layout size from the terminal driver.
> 
> > For instance, the postscript driver itself knows little about text
> > layout.  That information is not available until much later, when
> > the output file is run through a postscript interpreter 
> > (e.g. a PostScript printer, ghostscript). By then it is far to late
> > to feed any information back to the gnuplot core routines.

> A quick look at gd.trm reveals the following piece of code in ENHGD_put_text():
> 
>     /* EAM - Software text justification requires two passes */
>      if (png_state.justify == RIGHT || png_state.justify == CENTRE)
> 	ENHgd_sizeonly = TRUE;
> 
> So for most terminals you really need a way to get feedback about the text layout
> size.

I'm not sure we're all three of us on the same page here.
It may be that I misunderstood the original question.

The terminal driver itself may need to track such information
internally in order to implement enhanced text.
That is certainly true.

But I thought Chris's question was whether a driver was 
obligated to pass such information back to the core code.
The answer to that one is 'no'. 

It would be nice if the core routines *could* ask a driver
for specific details, but unfortunately this doesn't work
in general.  PostScript is a major example, but it is also
true for svg and x11.  

[OK, x11 could be made to work that way but it would probably 
require a new set of pipes between gnuplot and gnuplot_x11.
I did consider doing this at one point, but decided it was
too much work for too little gain.]

-- 
Ethan A Merritt
Biomolecular Structure Center
University of Washington, Seattle WA