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[css3-break] Was: [css-regions] Handling 0 height regions

From: Alan Stearns <stearns@adobe.com>
Date: Fri, 14 Sep 2012 15:10:02 -0700
To: Andrei Bucur <abucur@adobe.com>, "www-style@w3.org" <www-style@w3.org>
Message-ID: <CC78F4FE.162F9%stearns@adobe.com>
On 9/10/12 6:54 PM, "Alan Stearns" <stearns@adobe.com> wrote:

>On 9/7/12 1:09 AM, "Andrei Bucur" <abucur@adobe.com> wrote:
>
>>Hi!
>>
>>I'd like to clear-up how 0 height regions should be handled. The spec
>>currently does not take into account this edge case.
>>The main issue is wether they should generate break point considering
>>they
>>can't receive any content. For example:
>>#region1 { height: 0px; flow-from: flow;}
>>#region2 { height: 100px; flow-from: flow;}
>>P { margin: 10px; flow-into: flow; }
>>
>>What's the correct behaviour in this case? If region1 generates a break,
>>then the paragraph will not have a visual margin in region2 because the
>>margin collapse started in region1. If region1 is ignored, the block
>>starts in region2 and the margin will be present.
>>
>>Thoughts?
>
>I think I'd like to say that 0-height regions in a region chain are
>ignored while laying out content. But what about a region that is non-zero
>height, but still too small to fit any fragment of the named flow? I think
>if you change #region1 above to 'height: 2px;' it still should have no
>effect on how margins are displayed in #region2 (assuming default-sized
>line boxes).
>
>Thanks,
>
>Alan

This is another issue that should be defined in css3-break. This situation
can occur with regions, overflow:fragments boxes or columns if we specify
an individual column selector.

Elika, Rossen - what do you think of this addition to CSS Fragmentation?
Perhaps somewhere in section 5.1?

---
  A fragmentation context may contain fragmentainers
  that contain no portion of the fragmented flow.
  This can occur if a fragmentainer has zero height,
  or its height is too small to contain the next
  monolithic element and the UA chooses to overflow
  the fragmentainer instead of slicing the element.
  In this case, the empty fragmentainer is completely
  ignored. Layout continues with the next fragmentainer
  as if the empty fragmentainer did not exist.
---

Thanks,

Alan
Received on Friday, 14 September 2012 22:12:08 GMT

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