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

From: Simon Fraser <smfr@me.com>
Date: Wed, 17 Jun 2015 09:41:49 -0700
Cc: "Tab Atkins Jr." <jackalmage@gmail.com>, www-style list <www-style@w3.org>
Message-id: <96AA95D0-0C2C-4F04-8E10-7537ED09F7CF@me.com>
To: Dirk Schulze <dschulze@adobe.com>
> 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 <https://lists.w3.org/Archives/Public/www-style/2012Oct/0306.html>>

Simon


Received on Wednesday, 17 June 2015 16:42:43 UTC

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