W3C home > Mailing lists > Public > www-style@w3.org > April 2009

Re: [Backgrounds/Borders] Suggestion: Remove background-break and border-break

From: fantasai <fantasai.lists@inkedblade.net>
Date: Thu, 09 Apr 2009 12:13:46 -0700
Message-ID: <49DE48EA.4020401@inkedblade.net>
To: Brad Kemper <brad.kemper@gmail.com>
CC: "www-style@w3.org list" <www-style@w3.org>
Brad Kemper wrote:
> 
> I agree. Similarly, if you have a background that is supposed to align 
> with the top, bottom, or middle of the box, then it seems likely that 
> you would want it to break in the same fashion as border-break. That is, 
> if there are two border-tops and two border-bottoms for each element 
> because of a page break, then the backgrounds should similarly be 
> repeated on both pages. But if the border breaking policy is to treat it 
> as one box that's been sliced in two, then it should work the same way 
> for backgrounds.
> 
> It does seem to me that border-break and background-break should be the 
> same property. Thus, if border-break is "none", then background-break 
> should be "each box", otherwise should be "continuous". Then again, I 
> don't really understand the difference between "continuous" and 
> "bounding-box" (I don't think it is explained very clearly). 
> Is "bounding-box" really needed, or just for edge cases, or should it 
> replace "continuous"? It seems like it is trying to do something special 
> when there are varying page widths, but it is something nothing else 
> about the box does.

bounding-box vs. continuous becomes particularly relevant in multicol
elements.

Imagine my background image is a stretchable gradient

   :  :  : : :::

continuous for an element broken across 2 columns looks like

              +---------+
  +---------+ |  : : :::|
  |  : : :::| |  : : :::|
  |  : : :::| |  : : :::|
  |  : : :::| +---------+
  +---------+

That is, the background is rendered as if the boxes were pieces of

  +---------+
  |  : : :::|
  |  : : :::|
  |  : : :::|
  |  : : :::|
  |  : : :::|
  |  : : :::|
  +---------+

bounding-box looks like

              +---------+
  +---------+ | : : ::::|
  |    :   :| | : : ::::|
  |    :   :| | : : ::::|
  |    :   :| +---------+
  +---------+

That is, the background is rendered as if the boxes are cut out of

  +---------------------+
  |    :   :  : : : ::::|
  |    :   :  : : : ::::|
  |    :   :  : : : ::::|
  |    :   :  : : : ::::|
  +---------------------+


~fantasai
Received on Thursday, 9 April 2009 19:14:24 GMT

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