W3C home > Mailing lists > Public > www-style@w3.org > March 2015

Re: [css-sizing][css-flexbox] intrinsic min/max-width/height values and percentage children

From: Daniel Holbert <dholbert@mozilla.com>
Date: Mon, 2 Mar 2015 16:11:05 -0800
To: "Tab Atkins Jr." <jackalmage@gmail.com>
Cc: www-style list <www-style@w3.org>
message-id: <54F4FC19.2050909@mozilla.com>
On 03/02/2015 12:54 PM, Tab Atkins Jr. wrote:
> So, this doesn't work.
[...]
> If you have min-width:auto, then you need to calculate the min-content
> size of the flex item.  This doesn't care about the width or
> flex-basis, it cares about the min-size contributions of the flex
> item's children.  We thus can't treat a percentage on a child as
> resolving against a definite width here, because we're in the process
> of computing that width; but if the width isn't definite, then the
> percentage becomes auto *here*, and then a resolved definite value
> *later*, which is confusing and weird and two-pass, and we'd like to
> avoid two-pass layout in the default case.  (In other words, this
> becomes just a variant of the option C two-pass layout.)

Right -- this what I was trying to get across in
  https://lists.w3.org/Archives/Public/www-style/2015Feb/0489.html
and elsewhere in that thread, but you explained it here better than I did.

> So I think we're screwed and need to go with option A.

This is unfortunate, but I think I agree, for perf reasons (to avoid getting O(n^2) behavior *by default* for some pretty simple cases, due to the two-pass layout that can't really be avoided).

~Daniel
Received on Tuesday, 3 March 2015 00:11:35 UTC

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