xfig device (was [Rd] Re: [R] MetaPost device?)

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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