Add ability to set overlap bits for glyphs

Glyphs
1

It would be great if we could set the overlap bits for individual glyphs. In the OT spec, these are bit 6 for outline glyphs and bit 10 for composite glyphs, glyf - Glyf data table (OpenType 1.9) - Typography | Microsoft Learn

UFOs already have this covered, Glyph Interchange Format

2

Out of curiosity: where do you need this?

3

I apologise for the rabbit hole you’re about to fall into, Set overlap bit on every glyph in every VF and keep it set · Issue #4405 · google/fonts · GitHub.

4

I’ll think about this.
Would it be hurtful to just always set the bit?
If one would try to automate his, it needs to check all layers if they have an overlap?

5

Sorry for the delay, was on holiday.

Would it be hurtful to just always set the bit?

Unfortunately yes. AFAIK, FreeType takes around 4x longer to render glyphs with these flags set.

If one would try to automate his, it needs to check all layers if they have an overlap?

Correct.

6

And there might be overlaps that only happen between masters. So checking would not work 100%. I’ll have a look.