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Re: [css3-background] box-shadow spread Multiple Choice Question

From: Brendan Kenny <bckenny@gmail.com>
Date: Fri, 4 Jun 2010 12:41:15 -0500
Message-ID: <AANLkTinON92XyBXu81Qb3pgshBEkz1ZGYOK6z07tMDu4@mail.gmail.com>
To: fantasai <fantasai.lists@inkedblade.net>
Cc: "www-style@w3.org" <www-style@w3.org>
On Thu, Jun 3, 2010 at 5:56 PM, fantasai <fantasai.lists@inkedblade.net> wrote:
> Given that
>  a) We made some very significant changes to CSS3 Backgrounds and Borders
>     at the last F2F in March
>  b) We have not yet published a new official draft of the changes
>  c) The spec is already in CR, and therefore under Call for Implementations
> I think it is imperative that we publish a new official Last Call Working
> Draft asap.
>
> However! We still have an open issue, which is the behavior of box-shadow's
> spread radius. There are a fixed number of options that have been proposed.
> I will attempt to list them all:
>
>  1. Change spread to scale. The border-box shape is scaled up or down
>     in each dimension independently as necessary to increase its width
>     and height by the spread radius.
>
>     Note: If the width and height are not equal, this will distort the
>           shape.
>
>  2. Define spread as an outward outset normal to the original shadow
>     perimeter. (This is equivalent to a blur operation with a threshold
>     operation that makes all non-transparent areas solid, and to stroking
>     the perimeter of the border-box with a spread-radius-sized brush,
>     and is the strictest interpretation of a "spread" concept.)
>
>     Note: If the corner curves are not circular, the curves will no
>           longer be elliptical.
>
>     Note: If the shadow shape is contracted by more than the border-radius,
>           round corners will become sharp.
>
>  2a. As for 2, but special-case border-radius: 0; to be a sharp-cornered
>      rectangle.
>
>  3. Define spread as an outward outset of the box sides and a corresponding
>     increase in the border-radii.
>
>     Note: If the corner curves are not circular, the distance between the
>           original edge and the altered edge will not be constant.
>
>     Note: If the shadow shape is contracted by more than the border-radius,
>           round corners will become sharp.
>
>  3a. As for 3, but special-case border-radius: 0; to be a sharp-cornered
>      rectangle.
>
>  4. Define spread radius as outward normal outset, but allow implementations
>     to approximate as per 3.
>
>  4a. As for 4, but special-case border-radius: 0; to be a sharp-cornered
>      rectangle.
>
>  5. Drop spread radius from box-shadow.
>
> If I am missing your preferred option, please respond to this email with an
> explanation of your preferred option.
>
> For details on concepts 2, 2a, 3, 3a, 4, and 4a, see the editor's draft,
> which defines 4a, and thus has definitions for all the rest.
>  http://dev.w3.org/csswg/css3-background/#the-box-shadow
> If you think the above definitions are missing details... They are missing
> details! Check the spec before complaining that they are missing. I've added
> Brad's diagram and rearranged the text. If there are any outstanding
> editorial
> or clarificational comments, let me know, preferably *before* we discuss the
> topic on a telecon.
>
> Finally, I respectfully request that the chairs schedule ten minutes of an
> upcoming telecon to conduct a straw poll, hopefully resolve the issue, and
> approve publication of a css3-background LCWD. I also request that if the
> discussion takes more than 8 minutes that we take option 5 and publish. I
> understand that CSS2.1 is the top priority, but it is also urgent that we
> officially publish the major changes we made to background-clip.
>
> Thanks~
>
> ~fantasai
>

Is there a reason why (1) needs to be specified as a length? It seems
more natural to specify a scale as a number multiplier or percentage.
This would also preserve shape, regardless of width/height ratio.
Received on Friday, 4 June 2010 17:41:51 GMT

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