[NTG-context] active strings in luatex?

Mojca Miklavec mojca.miklavec.lists at gmail.com
Sun Jan 13 15:38:31 CET 2008


I only wanted to add a note:
XeTeX always converts, say, c + combining caron into a ccaron whenever
one exists in the font (and does that on a really low-level). If
ccaron doesn't exist (or if there's no such comination in unicode), it
simply requests both glyphs from the font (and only modern fonts have
those combining glyphs, I assume). In the case of LM, the font has
combining characters with zero width with the accent shifted to the
left, so that it looks OK on an average glyph (but in general, TeX
does a better job with combining characters) unless one requests two
accents.

In my opinion, LuaTeX should also be able to handle such combining
characters somewhere in the early stages (I have never followed the
low-level details of LuaTeX - very often "low level" means "mkiv" for
LuaTeX, so probably this still means - mkiv should handle that).

So, either ccaron or c+combining caron (or l+combining tilde) should
behave the same way:
- if there's such a glyph in the font, use it
- if there is no such glyph, combine the character from c and a caron
(but probably not the combining one! - different fonts have different
ideas of what a combining character should be)

Also, {\v x} and other strange combinations don't work in ConTeXt (I
guess it does in plain TeX) since ConTeXt MK II uses a clever way to
figure out if such characters exist in the font encoding, but
combinations of letters and accents that are not explicitely defined
that they should work, are ruled out, which is a pitty.

Mojca


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