On 9/28/2018 10:56 PM, Ulrike Fischer wrote:
Due to a question on tex.sx
(https://tex.stackexchange.com/questions/452969/luatex-fontfeaturefractions-on-turns-first-digits-into-superscripts)
I looked again (see
https://www.mail-archive.com/ntg-context@ntg.nl/msg84822.html) at
the frac feature.
The output is still not really satisfactory. With mode=node numbers
with slash looks okay, but single numbers are rather odd: only the
last digit has the correct size:
\starttext
\font\test={file:linlibertine_r.otf:mode=node;script=latn;language=DFLT;+frac}
\test
787347 125
it all depends on the font and lookups i guess
the logic can be a combination of:
1 - replace digit when followed by digit or slash
2 - replace digit when preceded by slash
3 - replace digit when preceded by fract digit
so a last digit not preceded will not
in fact one can then as well replace all digits non contextual
1/7 1/2 3/4 5/6 7/8 9/10 11/12 31415/27182 1000/1000000
\font\test={file:linlibertine_r.otf:mode=base;script=latn;language=DFLT;+frac}
\test
787347 125
1/7 1/2 3/4 5/6 7/8 9/10 11/12 31415/27182 1000/1000000
forget about base mode ... dependent on how the font does frac single
substitutions will be applied (maybe ligs)
\stoptext
(It could be a font bug, the output with xetex isn't good either).
fonts probably have a limited set of lookups
(the 5 and 7 suggests some inconsistency in the lookups)
i must admit that i've seen so many bad frac implementations that i
never use it (and it's definitely something that should be applied very
selectively, not on a whole text stream)
Hans
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