32-bit glyph IDs about colr-gradients-spec HOT 8 CLOSED

I would like to treat 32 bit gids as a standalone thing - ideally forming a group for it, filed w3c/font-text-cg#8 - rather than scattering issues like this all over the place. Accordingly, I propose to close this (again).

from colr-gradients-spec.

• building in forward compatibility to a future in which fonts can have > 64K glyphs?

Yes, this was my intention.

• keeping 4-byte-integral structures?

That's a non-issue to me since everyone has to support unaligned anyway.

Note that this adds at least 6 bytes of padding to every colour glyph. For an emoji font, that will be an additional 12K to 20K (or more?) of padding.

Right. But will definitely be a tiny bit of the font size, so I'm happy to "waste" that. Compression takes care of it for any download situations as always.

from colr-gradients-spec.

We care about the size at rest (e.g. in a system image) as well as the transfer size. I suggest we use uint16. If/when we are ready to introduce 32-bit gids we should make that as a global or spec wide change, perhaps introducing COLRv2 which is just v1 with a 4-byte offset.

from colr-gradients-spec.

I agree with Rod, it feels odd to have 32-bit GlyphIDs only in COLRv1. We can always change it later and bump COLR table version.

from colr-gradients-spec.

I propose to close this issue and pickup 32 bit gids and offsets as a standalone project, likely a W3C WG spawned from the shiny new CG. I imagine the end result of that is COLR gains the ability to support 16 or 32 bit gids, compiler can choose as appropriate for the specific font. @behdad would that work for you?

from colr-gradients-spec.

Definitely works for me, yes. Just be more code and spec to maintain. Go ahead and close though.

from colr-gradients-spec.

Reopening and filing under the "COLRv2" milestone

Also, I note that making GIDs 32-bit compatible before glyf et al are updated, was already done in CFF2, per https://lists.aau.at/pipermail/mpeg-otspec/2020-September/002369.html

from colr-gradients-spec.

Relevant crosslink: MPEGGroup/OpenFontFormat#10

from colr-gradients-spec.