Re: CSS Regions considered harmful (was: [css-regions] issue 16858 redux)

On Thursday 2014-01-23 10:13 -0800, L. David Baron wrote:
> On Thursday 2014-01-23 12:58 +0100, Johannes Wilm wrote:
> > I contacted the Firefox list or IRC a while back and asked for advice on
> >  how to implement something like
> > http://sourcefabric.github.io/BookJS/using the fragment-overflow
> > specification. The answer was that this isn't
> > possible, because the fragment spec requires all the fragments to be
> > siblings of oneanother.
> 
> What is it that isn't possible?
> 
> > This seems to significantly limit the use cases of
> > fragment-overflow. If you should decide to go for the fragment-overflow
> > specification instead, I would strongly recommend that you extend it to at
> > least cover all the current use cases of CSS Regions.
> 
> Just because Regions can do it doesn't mean it's a feature that
> belongs in the fragmentation system.  I think regions is addressing
> use cases by reordering fragments that ought to be addressed by the
> layout model rather than by the fragmentation model.  Addressing
> layout features in the layout model allows the layout model to be
> designed for performant in-order layout to address its use cases.
> This, in turn, doesn't require that existing layout systems,
> designed for layout in content order, end up being used by regions
> out-of-order in a way that's either going to be slow or buggy
> (depending on which sacrifices the regions spec makes).

Also, to be clear:  I think it would be great for CSS to have a
mechanism for reordering and changing the tree structure of its
input, before that input reaches the layout system.  Would that
address your use cases?

What I don't want is the reordering after fragmentation happens,
which requires the contortions of using a layout system designed to
deal with content in a certain order and giving it the content in a
different order.

-David

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                          https://www.mozilla.org/   𝄂
             Before I built a wall I'd ask to know
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