That's really cool. I ended up directly patching the font, but the patch itself would probably be easier to produce with some scripting. I'll definitely play around with your code. Thanks Hans!
2016-01-07 13:43 GMT+01:00 Hans Hagen <pra...@wxs.nl>: > On 1/6/2016 5:28 PM, Paolo Brasolin wrote: >> >> Hello. >> >> I am trying to add some custom ligatures to a font using a feature file. >> Everything works just fine, until I try what is called a chained >> contextual substitution, i.e. a GSUB lookup of type 6. >> I am studying the specs from >> >> http://www.adobe.com/devnet/opentype/afdko/topic_feature_file_syntax.html#5.f >> >> A simple example.fea that does not work for me is: >> >> >> languagesystem dflt dflt; >> >> lookup FOOBAR { >> sub B by Q ; >> } FOOBAR; >> >> feature foba { >> sub [A] B' lookup FOOBAR; >> } foba ; >> >> >> I'd expect it to replace B with Q only when preceeded by A. >> The same rule expressed with a lookup of type 8 works just fine: >> >> >> languagesystem dflt dflt; >> >> feature foba { >> sub [A] B' by Q; >> } foba ; >> >> >> Ultimately I would need to use multiple inline lookups, something like >> sub [A]' B' lookup FOO C' lookup BAR; >> >> Are inline lookups unsupported by the engine? >> That would seem strange to me. >> I'm probably missing some point, but I'm unable to find more >> documentation. >> Am I using the wrong syntax? > > > As we have a way to define additional features in context i played a bit > with contextual lookups. As a result we now have an additional type > chainsubstitution. In due time I will document this better (once it's > settled). I still need to think of a way to kick this into place at a > specific location in the sequence. > > Btw, contrary to fea extensions (not supported in the new font loader > anyway) these are runtime extensions i.e. not cached. > > I'll upload a beta. > > ---------------------------------------------------------------------- > > \startluacode > fonts.handlers.otf.addfeature { > name = "stest", > type = "substitution", > data = { > a = "X", > b = "P", > } > } > \stopluacode > > \startluacode > fonts.handlers.otf.addfeature { > name = "atest", > type = "alternate", > data = { > a = { "X", "Y" }, > b = { "P", "Q" }, > } > } > \stopluacode > > \startluacode > fonts.handlers.otf.addfeature { > name = "mtest", > type = "multiple", > data = { > a = { "X", "Y" }, > b = { "P", "Q" }, > } > } > \stopluacode > > \startluacode > fonts.handlers.otf.addfeature { > name = "ltest", > type = "ligature", > data = { > ['1'] = { "a", "b" }, > ['2'] = { "d", "a" }, > } > } > \stopluacode > > \startluacode > fonts.handlers.otf.addfeature { > name = "ktest", > type = "kern", > data = { > a = { b = -500 }, > } > } > \stopluacode > > \startluacode > fonts.handlers.otf.addfeature { > name = "ytest", > type = "chainsubstitution", > -- flags = { false, false, false, false }, > lookups = { > { > type = "substitution", > data = { > ["b"] = "B", > ["c"] = "C", > }, > }, > }, > -- steps = { > -- { > -- rules = { > -- { > -- before = { { "a" } }, > -- current = { { "b", "c" } }, > -- lookups = { 1 }, > -- }, > -- }, > -- }, > -- }, > data = { > rules = { > { > before = { { "a" } }, > current = { { "b", "c" } }, > lookups = { 1 }, > }, > }, > }, > } > \stopluacode > > \definefontfeature[stest][stest=yes] > \definefontfeature[atest][atest=yes] > \definefontfeature[mtest][mtest=yes] > \definefontfeature[ltest][ltest=yes] > \definefontfeature[ktest][ktest=yes] > \definefontfeature[ytest][ytest=yes] > > \starttext > > \startTEXpage > \definedfont[file:dejavu-serif.ttf*default]% > abracadabra\par > {\addff{stest}abracadabra\par} > {\addff{atest}abracadabra\par} > {\addff{mtest}abracadabra\par} > {\addff{ltest}abracadabra\par} > {\addff{ktest}abracadabra\par} > \enabletrackers[otf.*] > {\addff{ytest}abracadabra\par} > \disabletrackers[otf.*] > \stopTEXpage > > \stoptext > > > > > ----------------------------------------------------------------- > Hans Hagen | PRAGMA ADE > Ridderstraat 27 | 8061 GH Hasselt | The Netherlands > tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com > | www.pragma-pod.nl > ----------------------------------------------------------------- > ___________________________________________________________________________________ > If your question is of interest to others as well, please add an entry to > the Wiki! > > maillist : ntg-context@ntg.nl / > http://www.ntg.nl/mailman/listinfo/ntg-context > webpage : http://www.pragma-ade.nl / http://tex.aanhet.net > archive : http://foundry.supelec.fr/projects/contextrev/ > wiki : http://contextgarden.net > ___________________________________________________________________________________ ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://tex.aanhet.net archive : http://foundry.supelec.fr/projects/contextrev/ wiki : http://contextgarden.net ___________________________________________________________________________________
