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Re: [css3-flexbox] Computing the height of an auto-sized multicol element in a flex container

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Tue, 2 Oct 2012 16:15:40 -0700
Message-ID: <CAAWBYDBQDtWz4dK4hhCzWNhEOXF45uY7gchUZ616uZv2oF2b5g@mail.gmail.com>
To: Daniel Holbert <dholbert@mozilla.com>
Cc: www-style list <www-style@w3.org>, Ojan Vafai <ojan@chromium.org>
On Mon, Oct 1, 2012 at 6:35 PM, Daniel Holbert <dholbert@mozilla.com> wrote:
> On 10/01/2012 05:32 PM, Tab Atkins Jr. wrote:
>> I don't think you should interpet that "narrowest measure" quite that
>> literally for multicol elements.  Your interpretation *always* forces
>> multicol elements into a single column when you set "width:
>> max-content", which I think is very undesirable.
>
> Well, that undesirable thing is exactly what browsers do right now...
>
> Opera, Firefox, and Chrome all currently agree that a multicol element
> should only have a single column, when wrapped in a either a floated div
> or an inline-block (which I think are both ways of getting the
> max-content width):
> https://people.mozilla.com/~dholbert/tests/flexbox/multicol-sizing-1.html

After thinking about this a bit more, I actually think this is
reasonable.  It's the only way to maintain the invariant that
min/max-content are independent of surrounding layout; that is, that
they are "definite" sizes.

While we *could* adjust the layout algorithm to surgically address
this category of things, I think I'd prefer to just leave it as it is.
 It does mean that you'll have to explicitly set a multicol flex item
to be "width: fill-available;" if you want the "better" behavior where
it fills out the correct number of columns, but I think that's okay.
(The other similar case where this happens - a multiline column
flexbox - doesn't have the ability to pre-declare its number of
columns at all.)

>> We very specifically went with max-content over fill-available.  I
>> don't like it nearly as much, but it was intentional.
>
> I think this choice (max-content sizing for flex items) was wise for the
> general case.  But I'm wondering whether it might be wise to also add a
> special-case just for "align-self:stretch".  (Maybe you're saying that
> special-case was considered and rejected -- if so, ok.)
>
> I'm not convinced that I like the prospect of this special case, but
> given the apparent consensus among rendering engines about the
> max-content size of multicol elements, I think it could provide more
> intuitive behavior for multicol-in-a-flex-container.  I also don't think
> it'd affect many other types of flex items (but I haven't convinced
> myself of that yet).
>
> In any case: I mostly just want this to be clearly-defined and
> interoperable. :)

Yeah, granted.  In any case, it looks like Chrome's behavior is not
justifiable - there's nothing in the flexbox layout algorithm that
allows you to run an additional layout in the "stretch" case.

~TJ
Received on Tuesday, 2 October 2012 23:16:28 GMT

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