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Re: [css3-writing-modes] text-orientation:upright

From: MURAKAMI Shinyu <murakami@antenna.co.jp>
Date: Wed, 19 Sep 2012 14:04:50 +0900
To: John Daggett <jdaggett@mozilla.com>
Cc: www-style@w3.org
Message-Id: <20120919140449.80F4.C598BCD7@antenna.co.jp>
John Daggett <jdaggett@mozilla.com> wrote on 2012/09/18 15:38:46
> > My concern here is that the actual orientation will be font
> > dependent and that causes serious problem when we set
> > ‘text-orientation: upright’ for arrows (←↑→↓↖↗↘↙ etc.) and pointing
> > indexes (☜☝☞☟ etc.). These characters are rotated (MVO=R) in default
> > ‘text-orientation: mixed-right’ and we will often want to set
> > upright for these characters (e.g. for “⇧UP”). If fonts do not have
> > rotated vertical glyphs we will get the expected results, but
> > unfortunately most CJK fonts have rotated vertical glyphs for some
> > arrows, and it is font-dependent which arrows are rotated.
> 
> What you're saying is right but I don't think it's really so much of
> an issue in actual practice.  If you're suggesting that the value
> 'upright' should *not* enable the use of vertical alternates, then
> there will be a whole different set of problems with characters that
> *require* the use of vertical alternates (ideographic punctuation,
> square katakana, etc.).
> 
> If there are given codepoints for which an author is concerned about
> the use of vertical alternates, such as the arrow codepoints you list,
> they can always explicitly disable vertical alternates for text runs
> containing those codepoints:
> 
>   text-orientation: upright;
>   font-feature-settings: "vert" off;
> 
> The CSS3 Fonts spec defines explicit precedence rules for how features
> are applied in this case, the value of 'font-feature-settings' always
> overrides feature settings implied by other properties, so with the
> properties above the orientation will never vary depending on the font.
> 
> > Should we recommend to use the ‘text-combine-horizontal’ property
> > instead of ‘text-orientation’?
> 
> No, that's an abuse of that property.  Use 'font-feature-settings'
> instead to explicitly disable vertical alternates.

 I understand it's a current limitation but I tested
'-webkit-font-feature-settings: "vert" off' and found that does not
work on some WebKit-based browsers and EPUB 3.0 devices, 
and that's not a standard feature of EPUB 3.0 CSS profile.
This limitation will be solved in the future. But right now Japanese
EPUB 3.0 ebooks with vertical text are being made and they need 
a workaround; '-epub-text-combine:horizontal' can be used for 
such purpose.

> 
> That said, I don't think this will be needed in most cases, since this
> is really an edge case.  As more devices are available with fonts that
> are more consistent about their use of vertical alternates (i.e. a
> world without MS Gothic), the need to worry about this edge case will
> also evaporate.

I don't think this is an edge case. All modern Japanese fonts 
supporting vertical typesetting have rotated ←↑→↓ glyphs.
Using '←' for up-arrow in vertical text may be a workaround
but we want same up-arrow in both vertical and horizontal text.

Regards,

Shinyu Murakami
Antenna House
Received on Wednesday, 19 September 2012 05:05:12 GMT

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