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Re: [css3-multicol] Tests with wide or excessively wide column-gap

From: Morten Stenshorne <mstensho@opera.com>
Date: Mon, 29 Jul 2013 11:52:23 +0200
To: www-style@gtalbot.org
Cc: Håkon Wium Lie <howcome@opera.com>, "www-style mailing list" <www-style@w3.org>
Message-ID: <87k3k9puaw.fsf@aeneas.oslo.osa>
"Gérard Talbot" <www-style@gtalbot.org> writes:

> [src]
> http://test.csswg.org/source/contributors/opera/submitted/multicol/multicol-count-computed-001.xht
>
> [reftest]
> http://test.csswg.org/source/contributors/opera/submitted/multicol/multicol-count-computed-ref.xht
>
> When width of column-gaps equal the available width of a multi-column
> element, then used column-width of colum boxes should be 0px.
>
> (11)  if (column-width = auto) and (column-count != auto) then
> (12)    N := column-count;
> (13)    W := max(0, (available-width - ((N - 1) * column-gap)) / N);
> (14)  exit;
>
>   used width == max(0, (12em - ((3 - 1) * 6em)) / 3);
>   used width == max(0, (12em - (2 * 6em)) / 3);
>   used width == max(0, (12em - 12em) / 3);
>   used width == max(0, 0em / 3);
>   used width == 0px
>
>
> So, in this test, there should be 3 column boxes of each 0px wide. Now,
> §8.1 states:
> "
> Content in the normal flow that extends into column gaps (e.g., long words
> or images) is clipped in the middle of the column gap.
> "
> http://www.w3.org/TR/css3-multicol/#overflow-inside-multicol-elements
>
> So, I believe only the first 3 "x" of the <span id="pink"> should be
> displayed. And only the first 3 "x" of the <span id="orange"> should be
> displayed.
>
> §8.2 states:
> "
> overflow outside multicol elements
>
> Content and column rules that extend outside column boxes at the edges of
> the multi-column element are clipped according to the ‘overflow’ property.
> "
>
> And so (since default, initial value of 'overflow' is 'visible'), the 4
> "x" of the <span id="purple"> should be displayed, with the first,
> leftmost one overlapping the border-right. The 3 rightmost "x" of the span
> id="purple" should extend outside the multi-column element.
>
> The 2 blue column rules should be rendered too, with the left half
> (0.75em) of the first column rule overlapping the 3rd pink "x" and the
> left half (0.75em) of the 2nd column rule overlapping the 3rd orange "x".
>
> I believe the reftest is wrong.
>
> What am I missing?

Looks like this test was written for an older version of the spec:
http://www.w3.org/TR/2009/CR-css3-multicol-20091217/#pseudo-algorithm

In this version there are 10 lines dedicated to "insane" column-gap
values, but they are gone in the latest version of the spec. I'm pretty
sure both the tests and the Presto implementation (the implementation
was finished in February/March 2011, i.e. slightly older than the
current spec) were done with the 2009 version of the spec in mind.

This thread seems relevant:
http://lists.w3.org/Archives/Public/www-style/2010Nov/0434.html
Continues here:
http://lists.w3.org/Archives/Public/www-style/2011Feb/0143.html
Getting interesting here:
http://lists.w3.org/Archives/Public/www-style/2011Feb/0399.html

> --------------------
>
> [src]
> http://test.csswg.org/source/contributors/opera/submitted/multicol/multicol-count-computed-002.xht
>
> [reftest]
> http://test.csswg.org/source/contributors/opera/submitted/multicol/multicol-count-computed-2-ref.xht
>
> Here, the 2 column-gaps excede the available width. What should happen in
> such case?
>
> Should the given algorithm in §3.4 still be used? Because it seems (lines
> 11 to 14 mentioned above) can still apply...
>
> If we follow the given algorithm in §3.4, then used width of column boxes
> should be again 0.

Same problem again: this test was valid with the old version of the spec.

I think both these tests should be removed. They are invalid now.

-- 
---- Morten Stenshorne, developer, Opera Software ASA ----
------------------ http://www.opera.com/ -----------------
Received on Monday, 29 July 2013 09:52:44 UTC

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