Cross script kerning #811
Cross script kerning #811
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I think this is ready for review. |
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Several implementations can apply kerning cross-script, so instead of splitting cross-script kerning pairs, we now keep all kerning for scripts which have common kerning pairs in one lookup and split the rest.
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... as long as they have the same horizontal script direction, that is. Mixed script directions still aren't allowed in the same lookup, and that's ok. |
| } kern_Grek; | ||
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| lookup kern_Latn { | ||
| @kern1.Cyrl_Grek_Latn_Orya.bar = [a-cy]; |
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I wonder if these class names may get too long, I believe FEA imposes some limits on the length. Maybe it's fine and we do already take care of ensuring the names are compliant and unique?
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Interestingly, feaLib has a limit of 63 char limit on class names, but makeotf does not. fonttools/fonttools#3424 should fix this (and #588 as well).
We already make sure names are unique.
These were implemented to follow FEA spec, but makeotf does not seem to have a length limit on class names, and the glyph names limit (if it still has it, I didn’t check) seems like an implementation detail we don’t have to enforce. Fixes googlefonts/ufo2ft#588 See also googlefonts/ufo2ft#811 (comment)
Co-authored-by: Cosimo Lupo <clupo@google.com>
Co-authored-by: Cosimo Lupo <clupo@google.com>
Co-authored-by: Cosimo Lupo <clupo@google.com>
These were implemented to follow FEA spec, but makeotf does not seem to have a name length limit any more (or it has a very large one, I tested a 600-character name and it was accepted). Fixes googlefonts/ufo2ft#588 See also googlefonts/ufo2ft#811 (comment)
These were implemented to follow FEA spec, but makeotf does not seem to have a name length limit any more (or it has a very large one, I tested a 600-character name and it was accepted). Fixes googlefonts/ufo2ft#588 See also googlefonts/ufo2ft#811 (comment)
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It would also be nice to add some logging that reports if/when kerning pairs between glyphs from different scripts get merged into the same kern lookup, because it might be unintentional and the font developer may be inadvertently getting a sparser (and potentially larger?) GPOS table simply because some glyphs are being used in multiple script contexts (either because doubly cmapped or because substituted to by GSUB rules that make their script-ness ambiguous). |
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Thanks, lgtm. Feel free to merge when you're ready. |
Since several implementations can apply cross-script kerning, instead of splitting cross-script kerning pairs, we now keep all kerning for scripts which have common kerning pairs in one lookup and split the rest if any.
Fixes #808