Use abvm/blwm on USE scripts and Khmer

googlefonts / ufo2ft

A bridge from UFOs to FontTools objects (and therefore, OTFs and TTFs).

MIT License

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Use abvm/blwm on USE scripts and Khmer #567

Closed simoncozens closed 2 years ago

simoncozens commented 2 years ago

Add constants for list of Indic/USE scripts
Add USE and Khmer to abvm/blwm scripts

Fixes #566, #565, #522

behdad commented 2 years ago

Make sure you handle Myanmar as well.

simoncozens commented 2 years ago

MS suggests using mark for Myanmar, not abvm/blwm.

behdad commented 2 years ago

MS suggests using mark for Myanmar, not abvm/blwm.

Right.

khaledhosny commented 2 years ago

With this PR, my kashida mark to base is moved from mark feature to abvm/blwm and they don’t get applied for Arabic except in HarfBuzz.

khaledhosny commented 2 years ago

I guess this is because unicodedata.script_extension() returns {'Phlp', 'Arab', 'Mand', 'Ougr', 'Syrc', 'Mani', 'Sogd', 'Adlm', 'Rohg'} for 0x0640, but:

For characters that can b e used in multiple scripts, it should be added to all relevant features for these scripts, not only one of them.
If the font does not have any characters of a given script other than shared ones, it should not be considered (alternatively font’s languagesystems should to be consulted).