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Re: [css3-background] Where we are with Blur value discussion

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Wed, 14 Jul 2010 17:17:27 -0700
Message-ID: <AANLkTim7MeWm0no9TBk5mqYSa0YmUtEFlETp_bYsQUag@mail.gmail.com>
To: "L. David Baron" <dbaron@dbaron.org>
Cc: Aryeh Gregor <Simetrical+w3c@gmail.com>, Brad Kemper <brad.kemper@gmail.com>, Simon Fraser <smfr@me.com>, Brendan Kenny <bckenny@gmail.com>, www-style list <www-style@w3.org>
On Wed, Jul 14, 2010 at 4:56 PM, L. David Baron <dbaron@dbaron.org> wrote:
> On Wednesday 2010-07-14 16:19 -0700, Tab Atkins Jr. wrote:
>> That part's not acceptable.  Authors win over implementors in general,
>> and in this case having the authors perform mental math or
>> guess-and-check every single time they use a shadow (or force them to
>> develop an intuition for it) versus implementors figuring out the
>> proper conversion once and putting that in their code isn't even a
>> contest.  Authors win.
>
> Authors don't read the spec every time they use the 'box-shadow'
> property, and most don't read it ever.  So the spec should still
> describe how it works using existing terminology that implementors
> will understand.
>
> I'm fine with having you come up with a measurement that you think
> is better for authors.
>
> However, that measurement should be explained in the spec in terms
> of the normal terminology used to describe blur effects.
>
> And writing the explanation in terms of the normal terminology might
> lead you to discover places where you've invented your own
> terminology where the existing terminology will work just fine.

The problem, though, is that the "standard terminology" you're
pointing to is the standard *for gaussian blurs*, which I don't
particularly want to explicitly require.  At least, I don't think
Webkit wants to require that.

If we can get everyone to agree that we want to require a gaussian
blur, then I'm more than happy to provide the exact equation you can
plug the blur length into to get a stdev to hand to the gaussian blur
function.  I don't think everyone will agree to that, though.

Without specifying a precise algorithm that must be used, I don't
think there is any standard terminology to lean on.

~TJ
Received on Thursday, 15 July 2010 00:18:20 GMT

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