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

Re: [css-flexbox] Behaviour of percentage heights in column direction

From: Daniel Holbert <dholbert@mozilla.com>
Date: Mon, 9 Feb 2015 15:05:12 -0800
To: Peter Salas <psalas@microsoft.com>, "Tab Atkins Jr." <jackalmage@gmail.com>
Cc: www-style list <www-style@w3.org>
message-id: <54D93D28.7070608@mozilla.com>
On 02/09/2015 02:23 PM, Peter Salas wrote:
> Since the flex container explicitly determines the main axis sizes of each item by the flex algorithm, I'd argue that the main axis size of a flex item should be considered definite.

It sounds like you're saying *all* flex item main-sizes should be
considered definite, yes?

I think I disagree -- "definite" means "computable without inspecting
the content", basically.  And if we have "flex-basis:auto" on one of our
flex items, then the flexbox algorithm *necessarily* must look at the
content of that flex item.  So, this flex item's final size (produced by
the algorithm) is not really definite, because we can't compute it
without inspecting its content.

So, the spec handles this by saying that a flex item's main-size is only
definite if its flex-basis is definite -- because surely then, we don't
have to look at the content to determine the main-size.

Except, that gets to my original question -- even then, we likely *do*
have to look at the content, to evaluate the item's default
"min-height:auto".  This quantity (the min-height) is really as
important to the algorithm as the flex-basis is, when space is
constrained -- it may ends up directly setting the final main-size.

So, in cases where "min-height:auto" clearly makes a flex item depend on
the size of its contents, I don't see how we can consider its final size
"definite".

~Daniel
Received on Monday, 9 February 2015 23:05:43 UTC

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