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notofonts / tifinagh

Noto Tifinagh
SIL Open Font License 1.1
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inconsistency in GDEF class in Tifinagh #13

Closed jungshik closed 7 years ago

jungshik commented 8 years ago

In GDEF of Noto Sans Tifinagh, I found an seemingly inconsistent glyph class assignment that I don't understand.

For instance, I wonder why the first one is class 1 (base) while the second one is class 3 (mark). [1] 

<ClassDef glyph="uni2D592D5C" class="1"/>
<ClassDef glyph="uni2D622D5C" class="3"/>

image

If I understand GDEF glyph classes correctly, both seem to have to be assigned class 2 (ligature).

[1] https://www.microsoft.com/typography/otspec/gdef.htm

Unicode Tifinagh block chart: http://www.unicode.org/charts/PDF/U2D30.pdf

/cc @dougfelt @roozbehp @behdad

jungshik commented 8 years ago

In addition, both uni2D592D5C and uni2D622D5C are included in the base character list for lookup 0 (in GPOS) to be combined with U+030[12467], U+0323, U+0331. So, I don't understand different glyph classes assigned to them in GDEF.

behdad commented 8 years ago

There's no requirement that ligatures be marked as ligatures in GDEF. They have to, only if they need mark positioning on individual components, which might not be feasible if the ligature is inherently vertical...

jungshik commented 8 years ago

I gather that this inconsistency does not cause any user-visible/practical change. It's just a bit strange that there's an inconsistency (class 1 vs class 3). So, this issue is kinda just for book-keeping.

marekjez86 commented 7 years ago

NotoSansTifinagh-Regular.ttx.zip

all of the above are class 1

marekjez86 commented 7 years ago

the font is in noto-fonts-alpha