[OpenFontLibrary] Using OTS to detect a "buggy" web font

[Peter Baker]

Paul,

Did you build it yourself? There's apparently no Ubuntu package, and
I'm having trouble building from source . . .

Peter

On Sunday, June 5, 2011, Paul Flo Williams <paul at frixxon.co.uk> wrote:
> [Reposted here at Christopher's suggestion]
>
> My first upload to the reborn Open Font Library was Segment14, and it
> failed badly as a web font in Firefox 3.6.17 on Fedora, not displaying at
> all.
>
> Christopher Adams confirmed that it worked on the WebKit-based browsers
> Safari and Midori, and it works on my HTC Desire.
>
> After some minor, unrelated, cleanups, FontForge gave both the SFD and OTF
> files a clean bill of health, but it still wasn’t working in Firefox, so I
> took a deeper look and found that Mozilla had added the OTS font
> sanitizing library to Firefox from version 3.6.13, back in December 2010.
>
> OTS is mainly designed to be added as a font condom for OpenType-consuming
> applications, as Firefox apply it, but it also has a standalone checker
> called ot-serialize. OTS isn’t packaged in Fedora yet, so I collected it
> from upstream and ran it over my font, with these results:
>
> ERROR at /home/paul/projects/ots/ots-read-only/src/cff.cc:377
> (bool::ParsePrivateDictData(const uint8_t*, size_t, size_t, size_t,
> ::DICT_DATA_TYPE, ots::OpenTypeCFF*))
>
> Ugly. Still, it’s a “yes/no” tool, so I’m prepared to do a little hunting
> through the source to find out exactly why it hates me.
>
> The answer is that my FontForge source had a definition of BlueValues in
> the Type 1 Private dictionary. I don’t remember how it got there, because
> it is optional, but I had put one in, and I had defined it as an empty
> array. OTS decided that, if arrays exist in the Private dictionary, they
> must not be empty. With a quick snip, my font works again.
>
> I’ll certainly be adding OTS to my fonty toolchain, and it strikes me that
> this would be a useful tool for packaging and using in font reviews. You
> wouldn’t want to fail a review because of it, but it would certainly help
> to know whether a font will fail on the Web, which must be a large part of
> users’ expectations now.
>
> P.S. Christopher Adams has now opened a blueprint to add this to the Open
> Font Library toolchain.
>
> https://blueprints.launchpad.net/openfontlibrary/+spec/sanitiser-for-opentype
>
> --
> Paul Flo Williams
> http://hisdeedsaredust.com/category/fonts/feed
>
>