Stylistic sets and alts

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Eben Sorkin
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Joined: 27 Apr 2021

Stylistic sets and alts

Post by Eben Sorkin »

I think I recall reading that Kern-on looks to kern glyphs that have unicodes but not those with no unicode. In general this makes sense, but if you have stylistic sets you have to remember to code those manually at the end of the process - kind of like kerning for the workspace if you do that.

It may be that you could make a separate font with the stylistic set swapped in ( e.g. 'a.ss01' swapped for 'a' ), run kern on; and get your kern data to apply to a.ss01 from that. However, that might not save time vs just doing it manually with kern kraft or whatever.

So I have some questions:

1) Could Kern-on kern a select group of stylistic set varients by extending its existing logic? Maybe by treating .ss glyphs as if they used the unicode preceding the ".ssxx" name?

2) If it could, when might that happen? Obviously, no promises but I'm still curious.

3) If this is impossible what would you say is the most efficient way to move stylistic set kerning data from a swapped stylistic set font to the main one? Or would you advise against this model and say - 'No, that's a fool's errand. Don't even try that.'?
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Tim Ahrens
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Re: Stylistic sets and alts

Post by Tim Ahrens »

Hi Eben, Kern On applies your OT features and generates all relevant kerning pairs. No need to manually transfer any kerning. Btw, KO ignores the glyph names, all it needs is the OT features.

If there are any missing pairs, i.e. glyph-glyph pairs that you think should be kerned, but KO is not autokerning them please let me know and we’ll figure it out together!
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Tim Ahrens
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Re: Stylistic sets and alts

Post by Tim Ahrens »

Btw, there is some information in the Under the Hood video at around 4:30.
Eben Sorkin
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Joined: 27 Apr 2021

Re: Stylistic sets and alts

Post by Eben Sorkin »

I'll try this. Thanks!
psb1558
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Joined: 28 Jun 2022

Re: Stylistic sets and alts

Post by psb1558 »

First of all, thanks for this amazing tool, and for this useful forum!

I've read this thread and watched the "Under the Hood" video, and I'm having problems with KO not finding a number of glyphs referenced in OT features. The feature that's giving trouble (the one I've found so far, anyway) is calt, which in this case is invoking a lookup in the Prefix. That lookup contains chaining contextual substitutions which invoke other lookups containing single substitutions.

So my question is: are there some kinds of OT features that KO can't process? If so, are there any workarounds? Right now I'm going through a lot of pairs making them "user-set autopairs," and I fear having to do this too often (because it involves a good bit of the kind of tedium that KO is so very good at relieving!).
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Tim Ahrens
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Re: Stylistic sets and alts

Post by Tim Ahrens »

Sorry to hear about the missing pairs. Initially, I implemented and tested the generation of OT feature based pairs in Glyphs 2, and then found that Glyphs 3 writes some kinds of substitutions differently from Glyphs 2. I am aware that the implementation for Glyphs 3 – for complex substitutions – may not be complete yet. (Sorry, that was not high enough on my to-do-list.)

What you describe (chaining contextual substitutions) sounds very much like you are using such kinds of lookups.

Would you mind sending me the .glyphs file? Then I can add the implementation for the missing lookup types as quickly as possible. Thanks!
psb1558
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Joined: 28 Jun 2022

Re: Stylistic sets and alts

Post by psb1558 »

Thanks for the reply, Tim. The files are in Glyphs 2 format, but being edited in Glyphs 3 (because Glyphs 2 files work better with fontmake). You can grab either Elstob.glyphs or Elstob-Italic.glyphs at https://github.com/psb1558/Elstob-font/ ... er/sources. Look especially at glyphs b.lf, h.lf, k.lf and l.lf, and in the Prefix lookups calt_fligs_2 and lig_right.

For an added complication, I've set these glyphs to "no kerning" on the left. At a glance, kerning on the right for these glyphs may look fairly normal, but I've explicitly set a great many of their pairs to "auto."

I'm still very new to KO, and feeling my way along, so if you notice I'm doing anything wrong, please do mention it.

And I'll mention that, even though I'm doing some manual labor right now, KO is still saving me days and days of work.
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