Kerning classes in different scripts

[dstype]

Hi Tim, just bought KernOn and the same letter shape in different scripts, for instance with: A; A-cy and Alpha, they don't show as they belong to the same kerning classes even if they are exactly the same. Is there any workaround to solve this sort of issues? (Of course I can manually do that in order to avoid a gigantic number of kerning pairs)

[Tim Ahrens]

Hi Dino!

In Glyphs, glyphs from different scripts cannot be in the same kerning class. This has something to do with how Glyphs divides the kerning into subtables when you export a font. While Kern On creates the kerning classes, it is aware of these subtables that will be created by Glyphs (in fact, they are precisely simulated internally). It will not put A, A-cy and Alpha in the same kerning class even if they have identical shapes. If you were doing kerning manually you shouldn’t do this either. Sorry, couldn’t find a source for this but the topic must have been discussed somewhere.

[Tim Ahrens]

That said, the above rules are not set in stone. In fact, together with Georg, I have worked on concepts to optimize the kerning subtables, which saved about a quarter of data size compared to Glyphs’ current simple-and-robust approach. Maybe we’ll sit down again and work out how subtables could be optimized better.

[dstype]

Hi Tim, Thanks for the info. I wasn't aware if such Glyphs issue. I always made them into the same classes and it worked.