Re: [css3-regions][css3-gcpm] Thoughts on Plan A and Plan B

On Feb 21, 2012, at 11:52 AM, Brad Kemper wrote:

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> On Feb 13, 2012, at 2:47 PM, David Hyatt <hyatt@apple.com> wrote:
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>> (3) Problems with CSS Regions:
>> 	(a) CSS Regions require explicit elements right now in order to work. This is terrible. Ideally any solution for paged presentations would not involve having to spit out a bunch of elements just to support pagination. Especially for many of the simpler magazine-style layouts, CSS multi-column has a real edge here. This is the single biggest problem with the CSS Regions proposal right now.
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> As I understand it, CSS Regions does not require explicit elements. It just punts on how you would get other pseudo-elements, which you would then turn into regions. I think that in theory, you could flow content from a body::before to a body::after.

Right, it isn't that the regions spec is wrong. It's that there is no other spec defining how to use regions in a good way.

> 
>> 	
>> In other words, instead of thinking of this as Plan A vs. Plan B, I'd suggest we step back and define how to build pages of regions using all the layout systems we have at our disposal. I think then we will arrive at a fairly elegant solution. I do very much like the idea of CSS multi-column being the layout that you end up using by default for most pages, with more complex layouts being achieved using grids/positioning in conjunction with CSS properties to control flow placement/ordering (to handle the Sushi example above).
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> I completely agree with this approach. In my view, we almost have page masters right now, with @page and its related @rules, except that they are only masters for margin boxes and size, and not the main content area. If we added column-related properties to the properties that could be used directly with @page, then the simple case of having different column numbers, width, etc. per named page (or pseudo-class selected page) would immediately be available. If we add to that being able to right rule sets with selectors within @page (like you can within @region), then you would be able to change fonts, colors, widths, etc. of any element based on what page it was in. If you go one step further, and add the ability to create an arbitrary number of pseudo-elements per page, then you could use 'content' with them to put decorations wherever you want on whatever pages you want, not just in the margins. I have proposed '@slot()' for this. combining this with regions, and you could have content flow from region to region, page to page. You could have your sushi column in your example work, by flowing it into a slot that is on the title page and the third page, but not the second. Anything that didn't fit in a slot because of page size or other constraints would automatically go to the next available page with the same 'flow-from'.
> 

Yeah, we are definitely on the same page here. (Haha.) I would like to see column rules applicable to @page as well as the ability to define a set of slots for the page that can then be regions. The placement of the slots should be achievable with grid layout, floating or positioning.

> Combine all that with overflow:paged by making the pages it generates obey css3-page, and you've got a complete solution.
> 

Yes.

>> If the CSS Regions spec remains the way it is, though, with explicit elements and scripting being the only way to build the paginated content, then I think we'll have failed. Page masters/templates and automatic generation of regions has to be addressed, and the explicit element requirement needs to be removed. The list of questions I have regarding how the layout of explicit element flows works is just growing (everything from layout cycles to sizing to how they paginate, etc.). If regions could only be generated anonymously by pagination and/or multi-column, then many layout, pagination and styling issues just go away.
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> Anonymously means they can't be selected and styled though, which I consider a negative.
> 

I wasn't really using the spec term "anonymous." I just meant "they don't have a DOM element."

dave
(hyatt@apple.com)