Re: XeTeX 1.0 - request for comments

Le 14 oct. 05 à 22:56, Jonathan Kew a écrit :

> There are a few issues I know of already, so I'll mention those and  
> save you the trouble. Most are things that I'm already pretty sure  
> *won't* be done right now:

The two issues that immediately came to my mind are precisely two of  
them, alas!

> b. Lack of .vf support in the output driver. Not a high priority  
> for me, but I realize it further limits the selection of math fonts  
> you can use. The other major use for .vf's relates to supporting  
> various 8-bit font encodings, which should be a non-issue in the  
> Unicode world; if you need to use all those traditional TeX fonts,  
> then just use a traditional TeX!

VF support would be a major bonus, allowing people to use the various  
PS math fonts packages, such as mathptmx mathpazo etc. In this way we  
could have math fonts looking better than CM when combined with the  
various OS X fonts used for text thanks to XeTeX. I don't have this  
kind of problem myself, being lucky enough to own the Lucida fonts  
which don't require VF font features and blend well with the OS X  
fonts, but I imagine for other people it's a limitation.

> f. Proper individual character metrics when using native OS X  
> fonts. This is harder than it sounds, as TeX wants to know height,  
> depth, and italic correction for each character, and this  
> information is not present in fonts, only in .tfm's. And it can't  
> be derived accurately from the glyph outlines, either.

It's this problem which has prevented me so far to use XeTeX for all  
things TeX (I don't really mind about the speed issue with XeTeX  
compared with standard TeX). As soon as you're typing math in XeTeX,  
especially with subscripts and superscripts, or even changing fonts  
in the middle of a line (such as including a character from Lucida  
Grande -- e.g. an arrow -- in text written in Optima), you end up  
with irregular baselineskips, exactly as when mixing characters from  
Times and Symbol in old word processors like MacWrite Pro (maybe it's  
still the same in MS Word, I haven't tried).

As a result, to get aesthetically acceptable output, I have had to  
use tricks such as setting (in XeLaTeX) \baselinestretch to 1.2. I  
know the problem can be partly solved by changing \lineskiplimit to  
negative value, but I don't consider it a satisfactory fix as it as  
it alters the spacing before and after displayed equations as well.

Bruno Voisin