[texhax] xetex: using fonts with missing glyphs

[Uwe Lueck]

I wrote:
>"Susan Dittmar" , 26.11.2010 13:57:11:
>> I just did my first steps with xelatex and immediately ran into a problem.
>> I would like to use a font which has only a very sparse set of glyphs. Even
>> comma and fullstop are missing.
>>
>> Is there an easy way to tell xelatex which font to use as fallback for
>> missing glyphs? (This is for glyphs that are missing completely, like the
>> comma.)
>>
>> Is there an easy way to tell xelatex on a case-by-case basis which
>> glyph (or combination of glyphs) to use for a special missing glyph? (This
>> is for glyphs that can be replaced by existing glyphs.)
>
> I even never have tried xelatex at all and may be the wrong one to answer. 
[...]
> Another solution could be with active characters in the good 
> old way, but with unicode the active character is rather something 
> like an active byte working like a macro with parameters 
> (I guess ...)

finally I did RTFM; I was wrong.

TFM I R is Kew's paper in TUGboat 26-2. I even downloaded 
Michel Goossens' XeTeX Companion (just google).

With XeTeX, simply all characters are 16 bit. What I wrote 
came from my little experience with UTF-8.

So with XeTeX, you indeed could try things like

    \catcode`\,\active \def,{...}

Of course, this is difficult with comma-separated ... such as \fontspec 
(may need to be redefined to \catcode`\,=12 locally).

Such things become especially difficult when with hyperref 
labels contain text. In my niceverb.sty from the nicetext bundle 
I solved this by doing the \catcode assignment in the .aux as well.

Don't worry, be happy!

     Uwe.