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RE: [css3-writing-modes] a third option for implementing logical properties

From: Koji Ishii <kojiishi@gluesoft.co.jp>
Date: Mon, 25 Oct 2010 00:02:32 -0400
To: John Daggett <jdaggett@mozilla.com>, David Hyatt <hyatt@apple.com>
CC: "L. David Baron" <dbaron@dbaron.org>, "www-style@w3.org" <www-style@w3.org>
Message-ID: <A592E245B36A8949BDB0A302B375FB4E0AA363413D@MAILR001.mail.lan>
> For vertical text layout it's *not* an opt-in model because you need to
> somehow deal with display in browsers that only display horizontal text.
> The existing model of top/bottom/left/right is simple, an author doesn't
> need to scratch their head to remember, hmm, 'logical-width' is really
> height in vertical layouts.

We have both physical and logical model in current proposal, so if you like the physical model, you can continue using it. I think Dave said it's opt-in for that reason.

If you'd like to use logical model, it's more helpful than confusing. I as one of Japanese think logically, so I don't need to scratch my head to think whether it's horizontal or vertical. I just think about the length of line, and I know its direction can change depends on styles. It's more confusing if I have to think "this  is physical width in horizontal and physical height in vertical" when I think about the length of a line.

I understand it may not be easy to think logical layouts unless you used to do so. And that is why we're discussing how to mix physical and logical model, which leaves opt-in for people who want to keep using physical model.

In the world, there are people who had to be used to think layouts in logical way since 1st grade. And what we're saying is CSS provides opt-in model for that people.


> My point here is that if there are some elements that don't rotate within
> vertical text layouts, then simply flipping box properties based on the
> writing mode isn't always going to give you a workable layout in both
> vertical and horizontal modes.

As Dave said, it may not be 100%, but it serves 90% or more, and I hope you agree with it.

In Japanese text, we switch directions more often than you might imagine. It's just a stylistic property of a block for us. It's in "Format" menu for the every word processor. When I switch, I wish the software to preserve 90% or more of the format rather than completely destruct it and forces me to re-format from scratch.

Also there are people with dyslexia who can read only horizontal, or only vertical. A study showed that even without dyslexia, there are some people who takes 3 times longer to read horizontal text than to read vertical text. We need a reasonable fallback when directions are changed in user stylesheet for those people, even when author didn't create styles for a specific direction.


> Another interesting thing to point out is that the defaults for Western
> text don't really make sense as defaults for Japanese vertical text.  The
> margin settings above are the Webkit user agent stylesheet values.  With
> logical margins, the 1em top/bottom margins for horizontal layout become
> 1em left/right margins for vertical text layout. But vertical text layout
> in Japanese generally doesn't include spaces between paragraphs.  With this
> model there's no way for user agent stylesheets to use different defaults
> for different writing modes.

Murakami-san already pointed this out, but this is a different topic. Japanese generally doesn't include spaces between paragraphs, this is correct, but correct for both horizontal and vertical; it doesn't relate to the text flow. I always start writing from
P { margin-top:0px; }
And I wish it be margin-before:0px instead if vertical flow is supported in CSS.

MS Word has default style per language, and it sets "space-before-paragraph" to 0 in Japanese, regardless of the text flow. We may wish to re-visit this in future, but this is a different topic.


> Until all browsers in use support vertical text layout, authors designing
> layouts that use vertical text will need to consider the rendering in
> existing browsers.  So effectively, those authors will be designing dual
> layouts.

Not only for the existing browsers, but for the reason of accessibility and user preferences, I know I have to live with designing dual layouts. It is a burden for the Asian typography we cannot avoid. And logical directions make my life much easier by freeing me from duplicating styles everywhere.


Regards,
Koji
Received on Monday, 25 October 2010 04:00:33 GMT

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