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Re: [css3-text-layout] New editor's draft - margin-before/after/start/end etc.

From: MURAKAMI Shinyu <murakami@antenna.co.jp>
Date: Wed, 02 Jun 2010 17:48:50 +0900
To: Hakon Wium Lie <howcome@opera.com>
Cc: "L. David Baron" <dbaron@dbaron.org>, Boris Zbarsky <bzbarsky@MIT.EDU>, David Hyatt <hyatt@apple.com>, www-style list <www-style@w3.org>
Message-Id: <20100602174850.61E6.C598BCD7@antenna.co.jp>
Håkon Wium Lie <howcome@opera.com> wrote on 2010/06/01 16:59:01
> The current draft [1] seems to sketch a simpler model where:
>   - the properties are not real properies but aliases for existing
>     properties (although they are referred to as "logical properties";
>     this should probably be changed to "direction-dependent aliases"
>     (DDAs) or something, I'll use that term here)
>   - DDAs are mapped to their respective properties as soon as the
>     computed value of 'writing-mode' is known; thereafter DDAs --
>     their values and existence -- can be forgotton

I am OK with "direction-dependent aliases".
I used the term "conditional aliases" for same meaning:

| In Antenna House's implementation, the logical properties are treated 
| as conditional aliases of corresponding physical properties.
| Mozilla and WebKit seem doing same thing.

>   - there is no DOM access to DDAs (I hope, the draft doesn't say)
> This undertanding is supported by [2]:
>  > For UAs supporting only horizontal writing, *-before, *-after,
>  > logical-width and logical-height are simply aliases of *-top, *-bottom,
>  > width and height respectively. No costs needed.
> From this, however, it is unclear if the properties turn into "real
> properties" when/if vertical writing is supported.

The *-before, etc. will be pure aliases until vertical writing 
is supported, and turn into DDAs when vertical writing is supported.

> A clarification on this would be helpful in assessing the
> cost/benefits of DDAs vs other proposals.
> [1] http://dev.w3.org/csswg/css3-text-layout/
> [2] http://lists.w3.org/Archives/Public/www-style/2010May/0563.html


村上 真雄 (MURAKAMI Shinyu)
Antenna House Formatter:
Received on Wednesday, 2 June 2010 08:49:29 UTC

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