[MPEG-OTSPEC] Possible edit for LTSH and b64k

[Behdad Esfahbod]

Thank you for this. I filed the following issue with a proposal:

  https://github.com/harfbuzz/boring-expansion-spec/issues/132

behdad
http://behdad.org/


On Thu, Feb 1, 2024 at 10:46 PM Takaaki Fuji 藤 貴亮 via mpeg-otspec <
mpeg-otspec at lists.aau.at> wrote:

> Hello all,
>
> Sorry if I missed past discussions, but I found LTSH might also need a
> small change for the b64k proposal, where the 'numGlyphs' field is uint16.
>
> I checked the fonts currently available in macOS and Windows, and still a
> number of fonts include a set of VDMX/hdmx/LTSH table, possibly generated
> with the Microsoft’s CacheTT tool. I also found out that B612 (
> https://b612-font.com) is one of the recent fonts with those tables.
>
> For b64k fonts, I suppose just capping this field at 65,535 should suffice
> as you can put an arbitrary number of 'yPels' in the table anyway. Like the
> 'sbix' table, putting a line like
>
> > The glyph count is derived from the size of the ‘GLYF’ table when
> present, or from the 'maxp' table.
>
> into the description sounds nice to make sure b64k-aware clients should
> ignore the ’numGlyphs’ field in this table.
>
> So, in case this table is still in use, we might want to make a small
> edit. What do you think?
>
> Regards,
>
> Takaaki Fuji
>
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