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RE: [css3-background] Curved borders intersecting backgrounds of inner boxes

From: Brian Manthos <brianman@microsoft.com>
Date: Tue, 20 Apr 2010 10:56:18 +0000
To: Brad Kemper <brad.kemper@gmail.com>, fantasai <fantasai.lists@inkedblade.net>
CC: Zack Weinberg <zweinberg@mozilla.com>, W3C Emailing list for WWW Style <www-style@w3.org>
Message-ID: <FA122FEC823D524CB516E4E0374D9DCF014A8478@TK5EX14MBXC136.redmond.corp.microsoft.com>
Whenever I see phrasing like "appropriate curve", my default reaction is "it's not going to be clearly specified, begin preparing your follow-up refinement questions."

"A renderer is conformant to CSS Backgrounds and Borders Level 3 if, in addition to interpreting the style sheet as defined by the appropriate specifications".  A canonical list of such specifications would give this statement clarity and verifiability.  As it stands it's open-ended boilerplate which I find troubling as the definition of "conformance".

Perhaps change "appropriate specifications" to a link, targeting such a list?

I guess my concern is usage of the word 'appropriate' as shortcut to avoiding clear definition.

The usage in example XXI, in contrast, is...um...appropriate. ;)


-----Original Message-----
From: www-style-request@w3.org [mailto:www-style-request@w3.org] On Behalf Of Brad Kemper
Sent: Saturday, April 17, 2010 8:03 PM
To: fantasai
Cc: Zack Weinberg; W3C Emailing list for WWW Style
Subject: Re: [css3-background] Curved borders intersecting backgrounds of inner boxes

On Apr 17, 2010, at 6:34 PM, fantasai wrote:

> On 04/12/2010 11:41 AM, Brad Kemper wrote:
>>> I think 'background-clip' should just affect backgrounds, not other
>>> things like 'overflow'. 'border-radius' affects other properties
>>> because it changes the shape of the border and padding (and content)
>>> edges, but only affects them in that it changes that shape.
>> Good point. So then how do you determine the "appropriate" curve for 
>> border-radius overflow clipping? The CR says it is based on 
>> 'background-clip', but you are saying that should not affect overflow.
> The CR says that *backgrounds* determine the appropriate curve to
> clip to via 'background-clip'. It does not say which curve other
> clip effects use: that is determined by the property doing the
> clipping. In the case of 'overflow', the definition of 'overflow'
> says which edge to clip to. The 'border-radius' property just
> alters the shape of that edge, it does not change which edge.
> ~fantasai

Ah, so "the curve" in the second sentence ("Other effects that clip...also must clip to **the curve**.") does not necessarily refer to the same "appropriate curve" in the first sentence, if I understand you correctly. It's whatever edge is appropriate for that clipping effect. 

That's reasonable. Maybe someday we will have a "overflow-edge: border-box" property/value, but since the padding edge is the most useful one for overflow anyway, I'm in no hurry to change this. Perhaps an editorial change could clarify the meaning though, as I read "the curve" to mean the same curve that was deemed "appropriate" in the preceding sentence. Perhaps you would consider something like this:

Backgrounds, but not the border-image, are clipped to the appropriate curve (as determined by 'background-clip'). Other effects that clip to the border or padding edge (such as 'overflow' other than 'visible') also must clip to the curve _of that edge (the padding edge in the case of 'overflow)_. 
Received on Tuesday, 20 April 2010 10:59:15 UTC

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