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

From: Brendan Kenny <bckenny@gmail.com>
Date: Tue, 13 Jul 2010 16:55:06 -0500
Message-ID: <AANLkTimG8hM_LKP2vDs78XeFUTaLcK0C1eBr8SV6surC@mail.gmail.com>
To: "L. David Baron" <dbaron@dbaron.org>
Cc: Brad Kemper <brad.kemper@gmail.com>, www-style list <www-style@w3.org>, fantasai <fantasai.lists@inkedblade.net>, Brian Manthos <brianman@microsoft.com>, Simon Fraser <smfr@me.com>
On Tue, Jul 13, 2010 at 3:21 PM, L. David Baron <dbaron@dbaron.org> wrote:
> On Tuesday 2010-07-13 07:15 -0700, Brad Kemper wrote:
>> Arguments in favor of the distance measuring the Entire blur region width (current spec language):
>>
>> 1) The entire perimeter is blurred, outer and inner, not just
>> outer, so it is logical that the width of the entire blur effect
>> width should match the authored value.
>
> However, for 'text-shadow' the value is called the "blur radius",
> not the "blur diameter" (and has been called "blur radius" since
> http://www.w3.org/TR/1998/REC-CSS2-19980512/text.html#text-shadow-props ).
>
> (I'm not sure when the definition of 'box-shadow' changed from using
> the commonly-used term "blur radius" to using the new term "blur
> distance".)
>
> I'd also note that blurring is implemented as a generic
> transformation of images; it's not just something applied to edges.
> In that form, I think measuring in terms of the radius
> (approximating the concept of how far away from its original
> location can the color of a point can get) makes more sense than
> using the diameter (approximating the distance between the two
> farthest points in opposite directions that the color of a pixel can
> reach).
>
> So I also favor switching the definition of box-shadow to match
> text-shadow and to describe a blur radius rather than a diameter.
>
> -David
>
> --
> L. David Baron                                 http://dbaron.org/
> Mozilla Corporation                       http://www.mozilla.com/


"blur distance" was added very recently, I think just a few messages
before it was realized that the change would be an issue:

http://dev.w3.org/cvsweb/csswg/css3-background/Overview.src.html.diff?r1=1.232&r2=1.233&f=h

"blur radius" had been replaced with "blur value" the revision before that.
Received on Tuesday, 13 July 2010 21:55:43 GMT

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