"Class 0" in GSUB/GPOS

Simon Cozens
Posts: 792
The spec says:
Does "all glyphs not assigned to a class" literally mean every other glyph in the font or every other glyph in the coverage table or something else?
A font developer can assign any glyph to any class, each identified with an integer called a class value. A Class Definition table (ClassDef) groups glyph indices by class, beginning with Class 1, then Class 2, and so on. All glyphs not assigned to a class fall into Class 0.
Does "all glyphs not assigned to a class" literally mean every other glyph in the font or every other glyph in the coverage table or something else?
0
Comments
-
Answering my own question after a bit of experimentation, it does appear to mean “every other glyph in the font”. Which is a) cool and potentially very useful, b) extremely unwieldy to express in feature language, and therefore c) probably the reason why my font has been building for the past thirty minutes.1
-
Every other glyph in the font.
1 -
Yes, every other glyph in the font: a ClassDef creates a partition of glyphs for the entire font.0
Categories
- All Categories
- 46 Introductions
- 3.8K Typeface Design
- 476 Type Design Critiques
- 555 Type Design Software
- 1.1K Type Design Technique & Theory
- 640 Type Business
- 830 Font Technology
- 29 Punchcutting
- 507 Typography
- 120 Type Education
- 313 Type History
- 74 Type Resources
- 109 Lettering and Calligraphy
- 30 Lettering Critiques
- 79 Lettering Technique & Theory
- 530 Announcements
- 84 Events
- 110 Job Postings
- 166 Type Releases
- 169 Miscellaneous News
- 274 About TypeDrawers
- 53 TypeDrawers Announcements
- 119 Suggestions and Bug Reports