[MPEG-OTSPEC] Apple's use of hinting instructions (Re: CFF2 errata)

[Hin-Tak Leung]

 Behdad's little comment reminds me of a small investigation I had recently. Apple's Font Tools for Xcode 16 was released September 17, 2024 , about 6 week ago. It looks like that its libFontValidation.dylib , which is the font-checking backend of its command-line ftxvalidator tool and FontBook GUI font checking functionality, still cares about at least 1/4 of the hinting instruction errors/warnings that the last of Microsoft's Font Validator cares about.

Apple folks please feel free to confirm/deny or otherwise comment on this.

It is possibly quite difficult to see in practice, because truetype hinting is often done programmatically with ttfautohint / visual truetype these days. These tools don't let you create/insert intentionally flawed hinting instructions. I believe that, if you have a collection of intentionally flawedly hinted fonts triggering every one of MS FontVal's hinting instruction errors/warnings, Apple's Font Tools / FontBook checking would similarly complain about at least 1/4 of this hypothetical 'intentionally broken" font collection.


On 10/22/24 3:17 PM, Behdad Esfahbod via mpeg-otspec wrote:
Hi everyone,

CFF2 has a file size advantage over TrueType-flavored variable fonts, specially if one doesn't care about hinting (Android, Apple platforms, etc) but does care about (uncompressed) size.

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