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Re: [css3-values][css3-background][css3-transforms] <position> vs. transform-origin

From: Simon Sapin <simon.sapin@exyr.org>
Date: Sat, 23 Mar 2013 16:52:36 +0000
Message-ID: <514DDDD4.5020109@exyr.org>
To: "Tab Atkins Jr." <jackalmage@gmail.com>
CC: Øyvind Stenhaug <oyvinds@opera.com>, www-style list <www-style@w3.org>
Le 20/03/2013 23:11, Tab Atkins Jr. a écrit :
> On Wed, Mar 20, 2013 at 7:23 AM, Øyvind Stenhaug <oyvinds@opera.com> wrote:
>> On Wed, 20 Mar 2013 13:59:52 +0100, Simon Sapin <simon.sapin@exyr.org>
>> wrote:
>>> The syntax for transform-origin and perspective-origin seem to be the same
>>> as CSS 2.1’s <position> (I haven’t checked in details) but do not call it
>>> <position>. Does that mean that they are not extended if css3-background is
>>> supported?
>> I believe so.
> Technically, yes.
>> The transform-origin value type is different from that of
>> background-position in that a third component value represents a position on
>> the Z-axis rather than an offset to a preceding percentage/keyword.
>> (<http://lists.w3.org/Archives/Public/www-style/2012Mar/0195.html> has a
>> resolution concerning this.)
> I wish we could solve this. :/  The grammatical ambiguity is annoying.
>   It would probably be worthwhile to define a <3d-position> type,
> though, that just matches transform-origin's current grammar.

Using '<position> <length>?' would be ambiguous, right? Even with tricks 
like "parsing <position> should consume as many tokens as possible"?

>> That difference doesn't apply to perspective-origin, though, so that does
>> seem to be an issue. Has been reported earlier here:
>> http://lists.w3.org/Archives/Public/www-style/2012Jan/0964.html
> Looks like it got forgotten in the craziness of that thread.  It would
> indeed be nice (and backwards-compatible) to upgrade
> perspective-origin to a <position>.

I read half of that thread but I’ll probably stop here :)

Can we ask in the next conf call to have perspective-origin reference 
Values 3 for <position>, and leave the discussion of what <position> 
should be for another time?

Simon Sapin
Received on Saturday, 23 March 2013 16:53:21 UTC

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