Kern On

Hi,

am I doing something wrong – I set the model pairs in a big typeface (12 masters). In the slanted italics follow the Upright spacing, so I set them to build kerning based on the uprights.

I set the "Y." and "A*" in every master as a model pair, yet after building kerning the one of the pairs is not included.

It seems like those are quite basic pairs to be built in the system right? I've set the limit of the file size to 14 kB which results in over 3800 kerning pairs, but no Y. (The A* is kerned)

Any advice would be welcome! :)

I tested last night with larger file size, setting the kerning to "Auto" in Kern-On and mixing the settings in other ways - still no luck. Once the kerning was present but only in one of the masters. It makes no sense to me. Why if I set it to a "model" pair the kerning is not included in the final list?

Could you send me the file? Then I can have a closer look.

Hi Tim,

just sent it from borys@kosmynka.com. Cheers and thank you for having a look.

Thanks for the file. It took a while to understand what is going on but here is the explanation:

Your font contains RTL kerning. Kern On currently does not support RTL autokerning but it preserves existing RTL kerning, including the kerning groups. Since asterisk and period are kerned RTL, their kerning groups are treated as “protected” by KO. As you checked “re-generate kerning groups”, Kern On generates class kerning for all LTR-kerned glyphs (including asterisk and period), and this part of the code assumes these new kerning groups will be used. Later, as the new kerning groups are written to Glyphs, the protections kicks in, and when KO finally writes its kerning pairs, assuming the new groups are available, this fails.

I am not an expert in RTL kerning. It is common to have glyphs that have RTL as well as LTR kerning? The perfect solution would be if I implement a system that allows to re-generate the kerning groups except for those glyphs that are used in RTL kerning. That’s not trivial, though.

For now, what you can do is _not_ to activate “re-generate kerning groups”, then the kerning should be written correctly even if RTL kerning is present.

I quickly checked a few fonts on my computer and couldn’t find any that have kerning between Hebrew and period or asterisk. What’s the current best practice?

Wow! That's intense! Thanks so much for troubleshooting - I would have never figured that out on my end.

For the Hebrew - hard to say – I'll ask the designer that worked on the Hebrew in that project and let you know what they say if I have anything good.

ps. the solution works and the kerning seems to be progressing well. Now I just need to fine tune and I think it'll be good to go! Cheers!

Good to know!