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Re: [css-transforms] Why doesn't perspective-origin just use <position>?

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Wed, 17 Jun 2015 12:10:25 -0700
Message-ID: <CAAWBYDCjxkkdZJoUf=nh1i-P_ZMM4=g_YdJbGKiaWSfQRzf0tA@mail.gmail.com>
To: Simon Fraser <smfr@me.com>
Cc: www-style list <www-style@w3.org>, Dirk Schulze <dschulze@adobe.com>
On Jun 17, 2015 9:42 AM, "Simon Fraser" <smfr@me.com> wrote:
>>
>> On Jun 12, 2015, at 11:54 PM, Dirk Schulze <dschulze@adobe.com> wrote:
>>
>>> On Apr 8, 2015, at 4:37 PM, Tab Atkins Jr. <jackalmage@gmail.com> wrote:
>>>
>>> The 'perspective-origin' property specifies a point in a 2d box.  Why
>>> isn't its grammar just using the <position> production?  It looks like
>>> it's reusing the 'transform-origin' grammar, but without the 3rd
>>> coordinate.
>>>
>>> <position> is complicated enough that it's annoying to parse a grammar
>>> near it to figure out what's different/excluded.
>>
>>
>> I don’t know of a specific reason why we don’t use <position> on
perspective-origin.
>>
>> It looks like Gecko parses it the same way as transform-origin but
without the z coordinate.
>> WebKit and Blink use a special function just for perspective-origin.
Both can probably use <position>.
>>
>> Would implementations be willing to change?
>
>
> I forget if we’ve talked about this in the past, but we did have
discussion around transform-origin and background-position here:
> <https://lists.w3.org/Archives/Public/www-style/2012Oct/0306.html>
Yeah, transform-origin (unfortunately) can't just use <position>. (Damn
that 3-value syntax form!) But perspective-origin is 2d, so doesn't have
the same problem.

~TJ
Received on Wednesday, 17 June 2015 19:10:54 UTC

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