W3C home > Mailing lists > Public > www-style@w3.org > February 2011

RE: [css3-multicol] pseudo-algorithm

From: Sylvain Galineau <sylvaing@microsoft.com>
Date: Fri, 11 Feb 2011 01:40:06 +0000
To: Stephen Zilles <szilles@adobe.com>, Håkon Wium Lie <howcome@opera.com>
CC: "www-style@w3.org" <www-style@w3.org>
Message-ID: <045A765940533D4CA4933A4A7E32597E2AB5A92D@TK5EX14MBXC120.redmond.corp.microsoft.com>
[Stephen Zilles:]
> I find this whole discussion focusing on finding the "right" algorithm
> rather than focusing on what would a user want. That is, what is most
> important to preserve as the size of the area in which columns are to go
> changes (more explicitly shrinks).

+1. 

[snip]
> For example, I would like to understand the use case for allowing column-
> widths to go to zero. That means that no content would show. If one is not
> allowed to set a column-width of zero, then the system should not give
> that result in a fall back situation.


+2!
 
> In the long term, it seems reasonable to have a property that sets the
> minimum column-width. But, in the short term, it would be reasonable to
> establish a default value for that property, say 5 characters or 10
> characters. Yes, I know that that will cause some words to break in an
> arbitrary way, but that seems far less worse than losing any form of
> comprehensible text.
> 
> I would then argue that the rules that reduce the number of columns be
> used when the minimum column-width is hit and not when zero is hit.
> 
> I would interpret Sylvain's point as saying that the ratio of area used
> for column gaps to that used of column content should also be used to
> trigger a reduction in the number of columns. I do not, however, have a
> suggestion on how to use that ratio in the algorithm.

Actually, my suggestion is that column-gap is always a maximum gap width.
So in overconstrained situations, gaps are shrunk to preserve as much
content as possible. (The minimum amount of gap to preserve is where I
would tentatively suggest hardcoding a value) 

My first aim was simpler though: to point out that Hakon's proposal has 
such an effect and understand why it constitutes an improvement beyond
its mathematical ability to produce a column count closer to that which
was specified and 'less abrupt changes'. The latter are implicitly 
assumed to be 'better' and I don't yet understand why. 

> 
> So, lets first agree on what makes sense from the author (and viewer)'s
> point of view and then decide on the algorithm.
> 
> Steve Zilles
> 
> 
> > -----Original Message-----
> > From: www-style-request@w3.org [mailto:www-style-request@w3.org] On
> > Behalf Of Sylvain Galineau
> > Sent: Thursday, February 10, 2011 4:23 PM
> > To: Håkon Wium Lie
> > Cc: www-style@w3.org
> > Subject: RE: [css3-multicol] pseudo-algorithm
> >
> > > I've run a simulation to compare the two.
> > I know, I saw the earlier results. But it doesn't measure how much
> > surface goes to content vs. gap in the element. The exercise seems to
> > assume that the more columns, the better even though the result is a
> > large increase in the amount of the multicol element's surface
> > dedicated to honoring the gap. While it can be argued to be what the
> > author wanted - the column-width is auto but column-count and
> > column-gap are explicitly specified so the algorithm makes every
> > effort to honor the author's request - I'm not sure this is helpful as
> > it means column-width:auto might yield poorer result when, for
> > instance, the user snaps/tiles his window to half the screen space.
> >
> > In the results below, I go from
> > > 1200 to 0 in width. The resulting number of columns and their widths
> > > are shown in the comments to the right (with a "/" between
> > > them:
> > >
> > > width: 1200; column-gap: 125; column-count: 6; /* current: 6/95
> > > revised
> > > 6/95 */
> > > width: 1180; column-gap: 125; column-count: 6; /* current: 6/92
> > > revised
> > > 6/92 */
> > > width: 1160; column-gap: 125; column-count: 6; /* current: 6/89
> > > revised
> > > 6/89 */
> > > width: 1140; column-gap: 125; column-count: 6; /* current: 6/85
> > > revised
> > > 6/85 */
> > > width: 1120; column-gap: 125; column-count: 6; /* current: 6/82
> > > revised
> > > 6/82 */
> > > width: 1100; column-gap: 125; column-count: 6; /* current: 6/79
> > > revised
> > > 6/79 */
> > > width: 1080; column-gap: 125; column-count: 6; /* current: 6/75
> > > revised
> > > 6/75 */
> > > width: 1060; column-gap: 125; column-count: 6; /* current: 6/72
> > > revised
> > > 6/72 */
> > > width: 1040; column-gap: 125; column-count: 6; /* current: 6/69
> > > revised
> > > 6/69 */
> > > width: 1020; column-gap: 125; column-count: 6; /* current: 6/65
> > > revised
> > > 6/65 */
> > > width: 1000; column-gap: 125; column-count: 6; /* current: 6/62
> > > revised
> > > 6/62 */
> > > width: 980; column-gap: 125; column-count: 6; /* current: 6/59
> > > revised
> > > 6/59 */
> > > width: 960; column-gap: 125; column-count: 6; /* current: 6/55
> > > revised
> > > 6/55 */
> > > width: 940; column-gap: 125; column-count: 6; /* current: 6/52
> > > revised
> > > 6/52 */
> > > width: 920; column-gap: 125; column-count: 6; /* current: 6/49
> > > revised
> > > 6/49 */
> > > width: 900; column-gap: 125; column-count: 6; /* current: 6/45
> > > revised
> > > 6/45 */
> > > width: 880; column-gap: 125; column-count: 6; /* current: 6/42
> > > revised
> > > 6/42 */
> > > width: 860; column-gap: 125; column-count: 6; /* current: 6/39
> > > revised
> > > 6/39 */
> > > width: 840; column-gap: 125; column-count: 6; /* current: 6/35
> > > revised
> > > 6/35 */
> > > width: 820; column-gap: 125; column-count: 6; /* current: 6/32
> > > revised
> > > 6/32 */
> > > width: 800; column-gap: 125; column-count: 6; /* current: 6/29
> > > revised
> > > 6/29 */
> > > width: 780; column-gap: 125; column-count: 6; /* current: 6/25
> > > revised
> > > 6/25 */
> > > width: 760; column-gap: 125; column-count: 6; /* current: 6/22
> > > revised
> > > 6/22 */
> > > width: 740; column-gap: 125; column-count: 6; /* current: 6/19
> > > revised
> > > 6/19 */
> > > width: 720; column-gap: 125; column-count: 6; /* current: 6/15
> > > revised
> > > 6/15 */
> > > width: 700; column-gap: 125; column-count: 6; /* current: 6/12
> > > revised
> > > 6/12 */
> > > width: 680; column-gap: 125; column-count: 6; /* current: 6/9
> > > revised 6/9 */
> > > width: 660; column-gap: 125; column-count: 6; /* current: 6/5
> > > revised 6/5 */
> > > width: 640; column-gap: 125; column-count: 6; /* current: 6/2
> > > revised 6/2 */
> > > width: 620; column-gap: 125; column-count: 6; /* current: 4/61
> > > revised
> > > 5/24 */
> > > width: 600; column-gap: 125; column-count: 6; /* current: 4/56
> > > revised
> > > 5/20 */
> > > width: 580; column-gap: 125; column-count: 6; /* current: 4/51
> > > revised
> > > 5/16 */
> > > width: 560; column-gap: 125; column-count: 6; /* current: 4/46
> > > revised
> > > 5/12 */
> > > width: 540; column-gap: 125; column-count: 6; /* current: 4/41
> > > revised
> > 5/8
> > > */
> > > width: 520; column-gap: 125; column-count: 6; /* current: 4/36
> > > revised
> > 5/4
> > > */
> > > width: 500; column-gap: 125; column-count: 6; /* current: 4/31
> > > revised
> > 5/0
> > > */
> > > width: 480; column-gap: 125; column-count: 6; /* current: 3/76
> > > revised
> > > 4/26 */
> > > width: 460; column-gap: 125; column-count: 6; /* current: 3/70
> > > revised
> > > 4/21 */
> > > width: 440; column-gap: 125; column-count: 6; /* current: 3/63
> > > revised
> > > 4/16 */
> > > width: 420; column-gap: 125; column-count: 6; /* current: 3/56
> > > revised
> > > 4/11 */
> > > width: 400; column-gap: 125; column-count: 6; /* current: 3/50
> > > revised
> > 4/6
> > > */
> > > width: 380; column-gap: 125; column-count: 6; /* current: 3/43
> > > revised
> > 4/1
> > > */
> > > width: 360; column-gap: 125; column-count: 6; /* current: 2/117
> > > revised
> > > 3/36 */
> > > width: 340; column-gap: 125; column-count: 6; /* current: 2/107
> > > revised
> > > 3/30 */
> > > width: 320; column-gap: 125; column-count: 6; /* current: 2/97
> > > revised
> > > 3/23 */
> > > width: 300; column-gap: 125; column-count: 6; /* current: 2/87
> > > revised
> > > 3/16 */
> > > width: 280; column-gap: 125; column-count: 6; /* current: 2/77
> > > revised
> > > 3/10 */
> > > width: 260; column-gap: 125; column-count: 6; /* current: 2/67
> > > revised
> > 3/3
> > > */
> > > width: 240; column-gap: 125; column-count: 6; /* current: 1/240
> > > revised
> > > 2/57 */
> > > width: 220; column-gap: 125; column-count: 6; /* current: 1/220
> > > revised
> > > 2/47 */
> > > width: 200; column-gap: 125; column-count: 6; /* current: 1/200
> > > revised
> > > 2/37 */
> > > width: 180; column-gap: 125; column-count: 6; /* current: 1/180
> > > revised
> > > 2/27 */
> > > width: 160; column-gap: 125; column-count: 6; /* current: 1/160
> > > revised
> > > 2/17 */
> > > width: 140; column-gap: 125; column-count: 6; /* current: 1/140
> > > revised
> > > 2/7 */
> > > width: 120; column-gap: 125; column-count: 6; /* current: 1/120
> > > revised
> > > 1/120 */
> > > width: 100; column-gap: 125; column-count: 6; /* current: 1/100
> > > revised
> > > 1/100 */
> > > width: 80; column-gap: 125; column-count: 6; /* current: 1/80
> > > revised
> > 1/80
> > > */
> > > width: 60; column-gap: 125; column-count: 6; /* current: 1/60
> > > revised
> > 1/60
> > > */
> > > width: 40; column-gap: 125; column-count: 6; /* current: 1/40
> > > revised
> > 1/40
> > > */
> > > width: 20; column-gap: 125; column-count: 6; /* current: 1/20
> > > revised
> > 1/20
> > > */
> > > width: 0; column-gap: 125; column-count: 6; /* current: 1/0 revised
> > > 1/0
> > */
> > >
> > > In both cases, we will have to deal with very narrow colunmns.
> > That is a rather generous statement given cases like this:
> >
> > > width: 360; column-gap: 125; column-count: 6; /* current: 2/117
> > > revised
> > > 3/36 */
> >
> > The revised algorithm shrinks the column width by 70% ! In general,
> > the proposed revision is worst as the number of columns goes down as
> > the extra gap added by the new column is substracted from fewer
> > columns.
> >
> >
> > > I doubt that there's much to gain.
> > I'm not worried about gaining right now. I'm worried about losing
> > quite a bit of Content space for a poorer result.
> >
> > >
> > > However, I agree it's one of the options. Let's try list the options:
> > >
> > > 1) keep the current algorithm
> > >
> > >    + easy
> > >    - gives us abrupt changes (6 -> 4) in #columns
> >
> > I don't understand why abrupt changes in number of columns is an
> > issue. The solution you propose can result in drastic changes in the
> > amount of space available for content.
> > Why isn't that a relevant factor ?
> >
> > >
> > > 2) revise line 24 (by adding 1)
> > >
> > >    + no abrupt changes in #columns
> > >    + more consistant column widths
> > >    - more situations where columns are narrow
> >
> > See above. The result is less space available for content.
> >
> > > 3) always honor column-count
> > >
> > >    + that'll teach'em
> > >    + easy
> > >    - more situationw where column widths are zero
> >
> > I'll assume this is here for completeness.
> >
> > > 4) go to 1 column as soon as column-width reaches zero
> > >
> > >    + easy
> > >    - abrupt chance
> >
> > So by abrupt you really mean, 'furthest from specified column-count'.
> >
> > > 5) try adjust column-gap as the width decreases
> > >
> > >    + smooth, if we find the right formula
> > >    - complex?
> > >    - doesn't honor 'column-gap'
> >
> > Agree with those. My suggestion was to treat column-gap as a
> > max-column- gap.
> > I assume the content of the multicol is the most important part for
> > the author and the user, so when available space is scarce column-gap
> > always loses.
> >
> > > 6) introduce min-column-width (probably in combination with 2)
> > >
> > >    + fewer narrow columns
> > >    - would bring us back to last call
> > >    - more complex to implement
> > >    - there would still be lots of clipping
> >
> > Definitely more complex; #5 seems less complex and achieve some of
> > this by allowing column-gaps to shrink.
> 
Received on Friday, 11 February 2011 02:07:55 GMT

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