From telford@progsoc.uts.edu.au  Tue Apr 11 08:21:44 2000
From: telford@progsoc.uts.edu.au (Telford Tendys)
Date: Tue, 11 Apr 2000 17:21:44 +1000
Subject: xfig device (was [Rd] Re: [R] MetaPost device?)
In-Reply-To: <Pine.GSO.4.05.10004110718120.4502-100000@auk.stats>; from ripley@stats.ox.ac.uk on Tue, Apr 11, 2000 at 07:25:50AM +0100
References: <20000411113215.E7411@ftoomsh.progsoc.uts.edu.au> <Pine.GSO.4.05.10004110718120.4502-100000@auk.stats>
Message-ID: <20000411172144.A22534@ftoomsh.progsoc.uts.edu.au>

On Tue, Apr 11, 2000 at 07:25:50AM +0100, Prof Brian D Ripley wrote:
> On Tue, 11 Apr 2000, Telford Tendys wrote:
> 
> > > Even to plot "threshold" centred you need to know its width and height and
> > > depth: see GText.
> > 
> > In xfig you can choose for a string to be centered and then give it
> > the string and the centre-point and it figures out the rest, it also
> > outputs this correctly centred despite font variations.
> 
> Eh?  R allows proportional centring (adj can be between 0 and 1) and my
> point was that the R driver model *requires* the knowledge. As I said, see
> the code for GText.

Hmm, OK xfig only supports left, right and centre, and now I look closer
at the drivers I see that there is a slot for a string width function.
I also notice the PS driver supports the string width function by simply
summing up the character widths from the afm (see the PostScriptStringWidth
function in devPS.c).

So I agree, make the assumption that all xfig fonts are postscript fonts and
share code with the PS driver for string width.

There should be a fancier implementation of the string width calculation
inside the GNU ghostscript source somewhere. Since that is GPL code it
should be OK to paste into R (adapting it should not be too difficult),
this would include all kerning stuff and would guarantee compatability
between the R driver and the printout (if I remember rightly, gs is built
from lots and lots of little source files, each one implementing one function).

> My point, which you seem to have missed, is that existing code for font
> metric information could be used in an xfig driver.

Yup, I'm with you now.

	- Tel
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xfig device (was [Rd] Re: [R] MetaPost device?)
Telford Tendys