[MPEG-OTSPEC] Possible edit for LTSH and b64k

[Hin-Tak Leung]

 AFAIK, Microsoft's CacheTT precompiled 3 tables, LTSH, hdmx, and VDMX. May need to update the other two table's numglyphs and other fields.
    On Sunday, 4 February 2024 at 16:26:13 GMT, Hin-Tak Leung via mpeg-otspec <mpeg-otspec at lists.aau.at> wrote:  
 
  The version field in LTSH is going to be another case of "that field hasn't changed for 3 decades, it is possible that implementation(s) stopped wasting time reading it some years ago..." .
One would hope that the numGlyphs field, on the other hand, is read and cross-checked against maxp, head, etc in practical implementation(s), regardless of the version field.
    On Friday, 2 February 2024 at 19:08:39 GMT, Takaaki Fuji 藤 貴亮 via mpeg-otspec <mpeg-otspec at lists.aau.at> wrote:  
 
 Thank you so much! As for versioning I have no particular opinions and whatever is fine.

Regards,

Takaaki Fuji

> On Feb 3, 2024, at 3:31, Behdad Esfahbod <behdad at behdad.org> wrote:
> 
> 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
> 
> _______________________________________________
> mpeg-otspec mailing list
> mpeg-otspec at lists.aau.at
> https://lists.aau.at/mailman/listinfo/mpeg-otspec

_______________________________________________
mpeg-otspec mailing list
mpeg-otspec at lists.aau.at
https://lists.aau.at/mailman/listinfo/mpeg-otspec
  _______________________________________________
mpeg-otspec mailing list
mpeg-otspec at lists.aau.at
https://lists.aau.at/mailman/listinfo/mpeg-otspec
  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.aau.at/mailman/private/mpeg-otspec/attachments/20240204/bf1d9620/attachment.htm>