[texhax] The 'TeX ' metric table in OpenType fonts

[Paul Isambert]

Doug McKenna <doug at mathemaesthetics.com> a écrit:
> All (well, okay, Any) -
> 
> I've been messing around with OpenType/TrueType fonts, trying to 
> (re-)understand how the data structures work under the hood.  Basically, 
> a ".otf" (or ".ttf") file is an extensible list of tagged tables, 
> containing all variety of information.  Any software that reads the file 
> has the ability to ignore any table it doesn't understand.
> 
> There's dozens of table types, some for different platforms, different 
> software packages, etc.  I am trying to put together a list of as many 
> table tags as I can collect.
> 
> One in particular caught my eye: the FontForge program supports
> creating a 'TeX ' table type.  It's documented here (about halfway
> down the page):
> 
>  <http://cle.linux.org.tw/~edt1023/fontforge/non-standard.html>
> 
> But it plainly does not support all the information found in a ".tfm" 
> file.
> 
> Are there any fonts out there that incorporate this information?  Was 
> this just a FontForge experiement that went nowhere, because the only 
> program that cares about TeX Font Metrics is ... TeX, and it doesn't know 
> about OpenType font internals?  Is it for the benefit of XeTeX?
> 
> I can't find any other substantive information or discussion about this 
> OpenType table type, except the above link.
> 
> Que pasa?

I've never seen it in use either, but I think (I'm pretty sure, actually)
that LuaTeX can use it... but the OT loader in LuaTeX is based on
FontForge (and then you can do whatever you wish with the tables). I
don't think it was made for XeTeX, since the two projects are pretty
distinct, as far as I know, and XeTeX OT engine is based on something
else (ICU), again if I'm not mistaken.

Best,
Paul