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Re: Timed Text / CSS styling requirements

From: Pierre-Anthony Lemieux <pal@sandflow.com>
Date: Thu, 3 Aug 2017 08:05:46 -0700
Message-ID: <CAF_7JxBaMqFOkHyhCjtvYYbYmk=61vZW=T7cw_M8g1RZzPVc9w@mail.gmail.com>
To: Simon Fraser <smfr@me.com>
Cc: "www-style@w3.org" <www-style@w3.org>, Nigel Megitt <nigel.megitt@bbc.co.uk>
Hi Simon et al.,

Is the intent for CSS stroke-width [1] to have the same behavior as
-webkit-text-stroke-width [2]?

If so, it looks like stroke is not drawn outside the glyph outline,
but on the glyph outline, thereby hiding the fill of the glyph.

See code pen at: https://codepen.io/palemieux/pen/ZJpwxJ

This does not match subtitle/caption practice where the outline is
drawn outside and used to create a contrast between the fill of the
glyph and the background.

Can the stroke be drawn outside the outline?


-- Pierre

[1] https://www.w3.org/TR/fill-stroke-3/
[2] https://developer.mozilla.org/en-US/docs/Web/CSS/-webkit-text-stroke-color

On Tue, Aug 1, 2017 at 9:19 AM, Nigel Megitt <nigel.megitt@bbc.co.uk> wrote:
> Thanks for that Simon! I've updated the page with a "partial mapping" on the
> basis that while the outline thickness maps to stroke-width quite well, and
> there's good support for this in browsers (despite the spec being in FPWD),
> the blur radius length component in TTML has no equivalent. It's possible
> that some combination of text-shadow and stroke-width might achieve a
> similar visual effect.
> Kind regards,
> Nigel
> From: Simon Fraser <smfr@me.com>
> Date: Friday, 28 July 2017 at 19:35
> To: Nigel Megitt <nigel.megitt@bbc.co.uk>
> Cc: "www-style@w3.org" <www-style@w3.org>
> Subject: Re: Timed Text / CSS styling requirements
> On Jul 22, 2017, at 2:25 AM, Nigel Megitt <nigel.megitt@bbc.co.uk> wrote:
> Dear CSS WG,
> Following up from the request for horizontal review of TTML2 and also on an
> observation that mapping even some TTML1 styling permitted in the IMSC1 text
> profile is not straightforward, TTWG has created a wiki page [1] listing all
> the styling features in TTML2 and IMSC with their mapping to CSS where
> available, for review, with each classified as unsupported/partial
> mapping/direct mapping as appropriate.
> Disclaimer: there may be some errors in understanding in which case the
> mappings might be inappropriately classified. Review comments/fixes welcome.
> It's probably worth noting that the most important high level objective is
> for the styling requirements for subtitles and captions are supported in
> CSS.
> In terms of specific issues TTWG is probably less concerned about syntactic
> differences than semantic ones, since any CSS based TTML implementation
> would need to map syntax in any case.
> Thanks also to @dbaron for his email that began this assessment for us back
> in November.
> This alignment requirement is also being looked at by TAG at
> https://github.com/w3ctag/design-reviews/issues/138
> One update to this page:
> textOutline maps to the CSS fill and stroke properties
> (https://www.w3.org/TR/fill-stroke-3/) so should be labeled as "Unclear
> mapping", I think.
> Simon
Received on Thursday, 3 August 2017 15:06:38 UTC

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