[luatex] Unicode composite characters and TrueType fonts

[Daniel Flipo]

Le 25/05/2017 à 19:00, Ulrike Fischer a écrit :

> In short: the harfbuzz library in xetex tries to use the composed
> glyph if it exists. 
> 
> You can mimick this feature, by adding "ligatures" which combine the
> accent and the char. This here works for me on texlive 2017:

Both harfbuzz library in xetex and the "ligatures" option suggested by
Ulrike for luatex disturb the hyphenation process: the
"character+accent" are displayed as one glyph but count as two for
\lefthyphenmin and \righthyphenmin.

Example of flaw for French (\lefthyphenmin=2 \righthyphenmin=3):

\showhyphens{élargissons, élargissons} % second é = e^^^^0301

=> \TU/Verdana(0)/m/n/10 élar-gis-sons, é-lar-gis-sons

\showhyphens{éternité, éternité, éternités} % 4th é = e^^^^0301

=> \TU/Verdana(0)/m/n/10 éter-nité, éter-ni-té, éter-ni-tés,

Even if the coding "character+accent" is legal in Unicode, its usage
seems not to be fully supported neither in xetex nor in luatex.
Converting "character+accent" in the source file into a ready made
character is not a big deal anyway… currently, it looks to me like the
safest way to go.

-- 
Daniel Flipo