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Re: Native browser/CSS support for TTC (raw and/or within WOFF)?

From: Chris Lilley <chris@w3.org>
Date: Fri, 18 Oct 2013 19:08:26 +0200
Message-ID: <1755471403.20131018190826@w3.org>
To: John Hudson <tiro@tiro.com>
CC: public-webfonts-wg@w3.org
Hello John,

Friday, October 18, 2013, 6:27:11 PM, you wrote:

> On 18/10/13 9:12 AM, Chris Lilley wrote:

>> Rather than modify @font-face, I suspect the correct approach would be
>> to define a fragment identifier syntax (the part of a url after the #)
>> that points into a TTC.

> Jonathan and I discussed this briefly during the meeting in Portland. As
> I recall, the intended mechanism is indeed to enumerate fonts within a
> TTC, but at present any support for TTCs seems to access only the first
> font. Perhaps Jonathan has more details.

Accessing only the first font is a reasonable fallback if someone
references a TTC without indicating which font they want. I would
expect a standardised fragment syntax for TTC to use that as the
default behaviour.

>> So a TTC is a single file containing multiple sfnt streams. What is
>> the official defining document?

> A TTC is a sort of composite sfnt in which one or more tables are 
> typically shared by more than one font, with offsets recorded in a 
> TTCHeader table. The TTC spec is embedded within the OT spec:
> http://www.microsoft.com/typography/otspec/otff.htm

Thanks. So the entire TTC is an sfnt (specifically, an entire TTC can
be encoded as a single WOFF?)

> Most commonly, the technology is used for CJK fonts sharing a single 
> glyf table with different cmap entries for roman and italic Latin 
> subsets. As another example, we built Cambria Regular and Cambria Math
> as a TTC with a shared glyf table and different cmap, OS/2, OTL tables
> and, of course, name tables.

Interesting (and I saw the request for standardizing Math tables).

I was previously only aware of TTC used for CJK fonts, and I
understood a typical use case to be 'mostly the same' Japanese and
Simplified Chinese fonts with distinct glyphs for those code points
where Unicode unification at the character level required different
language-specific glyphs. I may well have misunderstood, though.

Best regards,
 Chris                            mailto:chris@w3.org
Received on Friday, 18 October 2013 17:08:27 UTC

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