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Re: [css3-background] vastly different takes on "blur"

From: Brad Kemper <brad.kemper@gmail.com>
Date: Sat, 12 Jun 2010 23:07:36 -0700
Cc: Simon Fraser <smfr@me.com>, "L. David Baron" <dbaron@dbaron.org>, Brian Manthos <brianman@microsoft.com>, "www-style@w3.org" <www-style@w3.org>
Message-Id: <52D1F5C4-718B-4991-B094-FA824D998C19@gmail.com>
To: fantasai <fantasai.lists@inkedblade.net>

On Jun 12, 2010, at 1:38 PM, fantasai wrote:

> On 06/12/2010 12:05 PM, Brad Kemper wrote:
>> 
>> On Jun 12, 2010, at 11:03 AM, fantasai wrote:
>> 
>>> Ok, I've updated the spec text:
>>>  http://dev.w3.org/csswg/css3-background/#the-box-shadow
>>>  http://dev.w3.org/cvsweb/csswg/css3-background/Overview.src.html.diff?r1=1.230&r2=1.231&f=h
>>> 
>>> Let me know if this is better.
>> 
>> Yes, the last paragraph you added looks very good to me.
>> 
>> I still think the word radius and radii should be removed, except when talking
>> about border-radius, but instead it seems to be there even more. The way we
>> are defining it, it is not a direct input of the Gaussian blur (Dave Benning
>> seemed hopeful that it could be mathified into such an input, to give the
>> results [or perhaps close approximation?] of the last paragraph added). and
>> it does not seem to be the radius of any other circle... was this a regression
>> of your earlier text where you had mostly removed that term?
> 
> Fixed.
> 
>> I also start losing track of where the sentence is going in the part about
>> positive and negative number, absolute values, etc. Maybe that part would
>> be better broken into bullet points for more clarity. A negative spread
>> on an outer shadow has the same sort of effect on the shape as a positive
>> spread on an inner shadow, and vice versa, but I didn't really get that
>> sense while reading this.
> 
> The general sense of what happens is given above, where the values are
> defined. This paragraph is the details of exactly how to interpret it.
> Anyway, I've tried to fix up the paragraph a bit, take a look now.

OK, it does make sense to me as I read it now. I didn't really understand before. And I see you added that it is twice the value you want to end up with. Yeah, that makes sense, since the blur is happening in two directions (in and out from the original edge, and only one of those directions will contribute to the spread width.

One more thing: You have this:

The UA may approximate this operation by taking an outward outset of the specified amount...

I think you need to add the inner shadow case to that, as you do in the "alternatively" case. So:

The UA may approximate this operation by taking an outward outset (inward for inner shadows) of the specified amount...

>> When you say "a positive blur [radius]", it sort of implies that there could
>> be a negative blur. So I think "a non-zero blur amount" would be better there.
> 
> Fixed.

Thanks. I really hope we can evidence of the major UAs converge on implementing this, prior to entering CR when prefixes are dropped.
Received on Sunday, 13 June 2010 06:08:13 GMT

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