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Re: Exposing Fundamental Primitives (was: [css-regions] Named Flows, Elements and Box Generation)

From: Alan Stearns <stearns@adobe.com>
Date: Mon, 28 Oct 2013 18:57:30 -0700
To: "L. David Baron" <dbaron@dbaron.org>, "Tab Atkins Jr." <jackalmage@gmail.com>
CC: Brian Kardell <bkardell@gmail.com>, François REMY <francois.remy.dev@outlook.com>, Johannes Wilm <johannes@fiduswriter.org>, www-style list <www-style@w3.org>, Hċkon Wium Lie <howcome@opera.com>
Message-ID: <CE94609D.14869%stearns@adobe.com>
On 10/28/13 6:18 PM, "L. David Baron" <dbaron@dbaron.org> wrote:

>On Monday 2013-10-28 17:35 -0700, Tab Atkins Jr. wrote:
>> On Mon, Oct 28, 2013 at 5:29 PM, L. David Baron <dbaron@dbaron.org>
>>wrote:
>> > On Monday 2013-10-28 17:02 -0700, Tab Atkins Jr. wrote:
>> >> Regions, or at least something very similar to them, are clearly the
>> >> primitive underlying Multicol and some of the more exotic Page
>> >> features.
>> >
>> > I don't think so -- these other features all describe their layout
>> > model in a way allows implementations to do layout in a specific
>> > order without such a multi-pass model.  And I'm not convinced that
>> > the complex multi-pass model is regions actually allows describing
>> > things like the intrinsic sizing of multicol.
>> 
>> This is also fine.  It's okay for the sugar to optimize things better
>> than authors can achieve on their own.
>> 
>> Sizing is a whole nother thing to eventually expose.  We're chipping
>> away at this piece by piece; don't think it's worthless just because
>> not everything has been revealed yet.
>
>I don't think "expose" is what regions is doing here.  This isn't a
>pre-existing primitive.  Sure, you can make it a new primitive and
>rebuild other things on top of it -- but that doesn't make it the
>thing they were built on before, nor does it make it the right
>primitive to build them on (which I don't think it is).

The way I've put it is that the CSSOM we provide for named flows and
region chains "explain" fragmentation. They make the inputs and outputs of
fragmentation accessible instead of hiding it behind CSS 'magic'. Multicol
and pagination don't necessarily need to be built directly on top of named
flows and region chains, but they can be partially explained by reference
to the fragmentation concepts in CSS Regions. There might still be some
'magic' involved in bridging the gap between CSS Regions and Multicol
(what Tab is describing as the sugar optimizing things better), but the
gap is much much smaller than it used to be.

If you do not think CSS Regions are the right primitive, I'd like to get
specific feedback why that might be. We have been improving the spec based
on feedback from implementors, authors, and polyfill-developers over the
last few years, but I expect there are still more improvements to make.

Thanks,

Alan
Received on Tuesday, 29 October 2013 01:58:10 UTC

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