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Re: [css3-exclusions][css3-gcpm] Reconciling exclusions and floats

From: David Hyatt <hyatt@apple.com>
Date: Fri, 17 Feb 2012 16:46:17 -0600
Cc: "www-style@w3.org Style" <www-style@w3.org>
Message-id: <898D6477-CBE3-4E83-BD58-9037DD3CC14F@apple.com>
To: Håkon Wium Lie <howcome@opera.com>
On Feb 17, 2012, at 4:17 PM, Håkon Wium Lie wrote:

> 
>> What I don't understand is why we would move from a float-model of
>> exclusions to a new model that applies to all block-level elements,
>> even normal flow elements. What is the value of allowing exclusions
>> to be applied to arbitrary layout schemes? If we instead
>> implemented precise positioning of floats, e.g., the "positioned
>> floats" idea, then we could limit exclusions to be applicable only
>> to floats.
> 
> Indeed. And, with the GCPM approach, exclusions would be able to
> describe the most common (if not the simplest) use case: a pull quote
> positioned between two columns.
> 
>  http://lists.w3.org/Archives/Public/www-style/2011Dec/0271.html
>  http://dev.w3.org/csswg/css3-gcpm/#the-float-offset-property

I like having shorthands for common cases. For more power I really want to use positioning. For example, a very common use case of just putting a pull quote in the center of a page that happens to be two columns could be done with the following syntax assuming you had positioned floats:

#myImage {
float: positioned;
position: page center;  // (Note that the latest draft of CSS3 positioning seems to make these two values exclusive, but you should obviously be able to center within a page).
}

That's pretty simple.

You could imagine also allowing column based positioning too to do floating to the top and bottom of columns.

#myImage { float: positioned; position: column; top:0 }

I think we need to not lose sight of the fact that in many of these magazine layout use cases the images are most definitely floating (as are sidebars, etc.). I don't see any distinction between an image that happens to intrude into multiple columns and float right vs. an image that intrudes into a normal single column flow and floats right. It would be silly to have to define the former using some completely brand new concept, e.g., to state that you have to make a region just to hold the float, etc.

Floating images should work with multi-column layout and pages regardless of what gets defined with regions and page templates.

I believe if we allow floats to also be positioned objects (something I have even already prototyped in WebKit and that turned out to be a surprisingly simple change), then floats can simply *be* exclusions, and we'll have all the power we need to put exclusions everywhere authors would want.

dave
(hyatt@apple.com)
Received on Friday, 17 February 2012 22:46:47 GMT

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