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Re: SVG in OpenType proposal

From: Leonard Rosenthol <lrosenth@adobe.com>
Date: Fri, 1 Feb 2013 05:21:45 -0800
To: Cameron McCormack <cam@mcc.id.au>
CC: "public-svg-wg@w3.org" <public-svg-wg@w3.org>
Message-ID: <CD312505.8323%lrosenth@adobe.com>
On 1/31/13 8:08 PM, "Cameron McCormack" <cam@mcc.id.au> wrote:
>Would you be able to enumerate the problems for me, with pointers back
>to your mails that you brought them up in (which I am sure you have
>already done)?  

I don't know that I can find the original emails, but I can certainly
bring the main issue up again for discussion.

Your design/specification presumes (assumes?) that the SVG-based glyphs
will be rendered inside of a "web context".  This is extremely problematic
not just for the potential uses of these glyphs in a variety of non-web
contexts. Let me call out three such examples:

- alternate document formats (eg. PDF, ODF or OOXML)
- operating systems (eg. Windows, Mac OS, iOS, Android)
- authoring environment (eg. Word, DreamWeaver, iBooks Author)

In each of these cases, the parent context is not "the web". This raises
issues in two areas - animation and inheritance.

The animation issues are addressed in the Adobe proposal by providing a
way to have each glyph identified as animated or not (without requiring
parsing the SVG) so that a non-animated renderer or one that isn't running
on a web context can choose the static one (either a static SVG or the
classic glyph).  However, neither specification adequately addresses the
"animating outside the glyph's bounding box" problem that was raised in
email discussions earlier.  This will need to be called out/addressed, in
some fashion, in the final specification.

Regarding inheritance, your proposal introduces the "context-XXXX"
attribute values but in doing so (and in the examples provided) assumes
that the glyphs are being rendered inside of a web-context. No
consideration is given for a context that has completely different and/or
incompatible attributes. This is why the Adobe proposal specifically
leaves these for a future specification during which time the complex
issues can be evaluated and (hopefully) resolved.

A smaller issue, which may simply be something missing in your text (vs. a
design choice) is how the glyph position/layout is accomplished.  In the
Adobe specification, it specifically calls out that glyph sizes are the
same for SVG-glyphs as they are for classic glyphs - thus not requiring
any changes to the line layout algorithms (and enabling the same content
to appear w/o reflow when switching glyph types).  We (Adobe) believe this
is an extremely important aspect of the specification.

Received on Friday, 1 February 2013 13:22:15 UTC

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