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Re: [css3-break] fragments vs boxes (what is a box?)

From: Dirk Schulze <dschulze@adobe.com>
Date: Fri, 3 Jan 2014 07:25:23 +0000
To: Robert O'Callahan <robert@ocallahan.org>
CC: www-style <www-style@w3.org>
Message-ID: <0CD51FD7-22C2-4C40-94CA-79461DB2F05A@adobe.com>

On Dec 31, 2013, at 1:53 AM, Robert O'Callahan <robert@ocallahan.org> wrote:

> In CSS 2.1, inline elements are described as splitting into multiple boxes:
> http://www.w3.org/TR/CSS2/visuren.html#inline-formatting
> I always assumed that therefore each fragment of an inline element had its own border-box, padding-box, content-box, etc. And therefore at that point it made sense for CSSOM-VIew to define getClientRects() to return a list of rectangles, one rectangle per border-box. Each fragment having its own border-box, padding-box, etc is also very useful for defining how those fragments are laid out and how they render borders, backgrounds etc.

The CSS Regions spec supports your interpretation [1], even though it does not clarify which box is used for getClientRects() for each region.

I really donít think it should be in the CSS Regions spec but rather in CSS Fragmentation or CSSOM View though.

> 
> But I've just realized that the CSS3 Fragments spec talks about elements --- including inline elements --- having a single 'box' that breaks into multiple 'fragments'. So here are a couple of questions that need clarification:
> -- Does each fragment have its own border-box, padding-box, etc? If so, does it make sense for a spec to talk about "an element's border-boxes", meaning the border-boxes of its fragments? If not, how are we to describe the equivalent of the border-box of each fragment (the rectangle that's the outside edge of the border of the fragment)?
> -- Should we really be talking about a 'box' consisting of multiple fragments? To me a 'box' suggests something rectangular, not something whose geometry is a list of rectangles. If the answer is nevertheless "yes" then we need to indicate, probably in CSS3 Fragments, that the splitting of boxes described in CSS 2.1 is obsolete terminology. We would also need to eliminate all references to 'CSS boxes' that expect them to have rectangular geometry.
> 
> Rob
> -- 
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Greetings,
Dirk

[1] http://dev.w3.org/csswg/css-regions/#cssomview-getclientrects-and-getboundingclientrect
Received on Friday, 3 January 2014 07:25:58 UTC

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