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Re: [ttml2] embedded content, background image styling, other edits

From: Glenn Adams <glenn@skynav.com>
Date: Wed, 26 Nov 2014 07:51:51 -0700
Message-ID: <CACQ=j+c6NuXnx920uj8t2JH5TkUg1-AEC2cUNq5wV_-gQ8-rVQ@mail.gmail.com>
To: John Birch <John.Birch@screensystems.tv>
Cc: "public-tt@w3.org" <public-tt@w3.org>, "tai@irt.de" <tai@irt.de>, "nigel.megitt@bbc.co.uk" <nigel.megitt@bbc.co.uk>
On Wed, Nov 26, 2014 at 7:41 AM, John Birch <John.Birch@screensystems.tv>
wrote:

>  That note may also need to be referred to from the font-face section too?
>
> It would seem that (except for ASCII / LATIN 1) as mentioned, the use of
> the Unicode ‘range’ element becomes almost mandatory when a resource is
> referenced internally?
>

Not really. The only use of family, style, weight, and range attributes on
<font/> are to allow font selection processing to reject use of a font
without actually having to access/load the font. Further, the range
element, if specified would only indicate the character range supported by
a subsetted font (if it were indeed subsetted).

In the absence of a range attribute (not element) the font selection
algorithm *may* need to load the font resource and use the internal CMAP
tables (or equivalent) to determine the effective range(s) of coverage. But
if that font were later in the prioritized list of font candidates (for
selection processing) then it may not even be accessed (or loaded) if a
font earlier in that list satisfies the selection criteria.

So, the answer about whether range is useful or not: it depends.


>
>
> Best,
>
> John
>
>
>
>
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> *From:* Glenn Adams [mailto:glenn@skynav.com]
> *Sent:* 26 November 2014 14:37
> *To:* John Birch
> *Cc:* public-tt@w3.org; tai@irt.de; nigel.megitt@bbc.co.uk
> *Subject:* Re: [ttml2] embedded content, background image styling, other
> edits
>
>
>
>
>
> On Wed, Nov 26, 2014 at 7:30 AM, John Birch <John.Birch@screensystems.tv>
> wrote:
>
> Thanks! I'll follow up Nigel's proposal. As indicated, I don't view it as
> a strong requirement (for STL files)... Not sure about this concept for
> other large resources (like fonts)...
>
>
>
> btw, for fonts, you should be using subsetted fonts, i.e., containing only
> glyphs for characters used in a document; with an ASCII or LATIN-1 only
> font, this won't make much difference, but for modern Unicode fonts
> covering multiple scripts or for CJK fonts, this makes a huge difference;
>
>
>
> i will add a note in the section defining the font element reminding
> readers of this fact
>
>
>
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Received on Wednesday, 26 November 2014 14:52:38 UTC

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