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Re: h

From: Liam R E Quin <liam@w3.org>
Date: Thu, 10 Oct 2013 09:52:10 -0400
Message-ID: <1381413130.20642.46.camel@slave.barefootcomputing.com>
To: fantasai <fantasai.lists@inkedblade.net>
Cc: www-style@w3.org, Håkon Wium Lie <howcome@opera.com>
On Thu, 2013-10-10 at 00:03 -0700, fantasai wrote:
> On 07/19/2013 03:47 AM, Morten Stenshorne wrote:
[...]
> > The spec isn't very strict about this, other than "don't break more than
> > you have to" and "don't break inside truly unbreakable stuff". But it
> > also seems to suggest that fragmentainer heights be balanced (like in
> > multicol?), but that seems weird to me. If you have a text document that
> > needs one and a half pages, should you then make both pages 75% full,
> > rather than filling the first one completely and leaving the second one
> > half empty?
> 
> I think "end of content" counts as a forced break. I'm not entirely
> sure what was in mind when these rule were written (they date back
> to CSS2.0). I've asked Håkon if he remembers what was on his mind
> wrt even heights, since I believe he was in charge of that chapter...
>    http://www.w3.org/TR/1998/REC-CSS2-19980512/page.html#q16
> 
> Liam might also have an idea. Liam?

Yes, end of content should be a force break. One way to achieve this
might be to give the html or body element a page-break-after: always
value in the user agent stylesheet. CSS2.1 is rather sketchy in this
area.

More detail:

A system that can balance pages will generally only vary the height of a
page to a maximum, and usually in print at east there's a limit of a
difference in height of 1 line between successive double-page spreads
(both pages on a spread, that you see at the same time, should always be
the same height as each other of course).

So you might add 1 line to pages 2 and 3, then add 2 lines to pages 4
and 5, then add only one line again to pages 6 and 7.

But the end of content is yes a forced page break, and the only
balancing expected there is that you don't want to have just one or two
lines at the top of a page, so you might have a balancing algorithm
(widows and orphans) to try to prevent that.

So, if you have 1.5 pages worth of content you'd normally just end up
with one full page and one half-full page. If you have one page plus one
line, and it's possible, you should squeeze everything onto one page.

The page balancing algorithms try to fill pages as evenly as possible,
not to spread out content so that pages are not full. I see Håkon has
already replied to mention show-through; this also means you often can't
vary the line spacing to balance pages, although that depends partly on
taste and partly on the kind of ink and paper being used.

Hope this helps,

Liam

-- 
Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
Pictures from old books: http://fromoldbooks.org/
Ankh: irc.sorcery.net irc.gnome.org freenode/#xml
Received on Thursday, 10 October 2013 13:52:12 UTC

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