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

From: Greg Whitworth <gwhit@microsoft.com>
Date: Sat, 21 Jun 2014 04:33:31 +0000
To: Jon Rimmer <jon.rimmer@gmail.com>
CC: Tab Atkins Jr. <jackalmage@gmail.com>, www-style list <www-style@w3.org>
Message-ID: <a1ad5c68dcb34c65b76dedeff4d79f48@DM2PR03MB400.namprd03.prod.outlook.com>
> The problem is, determining the size of flex items, even when they're within
> a definitely sized parent container, requires you to calculate their content
> size when they don't have a definite flex basis. See item E in the algorithm
> for calculating the flex base size.[1]
> If the size of their content is playing into their own sizing algorithm, then they
> can't be definite.
> Jon
> [1] http://dev.w3.org/csswg/css-flexbox/#algo-main-item

Right, I'm not debating that there might be scenarios that authors get themselves into where they want child elements to be resolved against their parent but can't due to recursion where the child is asking its parent for its dimensions but the parent is requesting the same of its children. In that case I agree that nothing should appear [1] (updated fiddle showing this is what occurs in FF/IE/Chrome). 

But when you take the example I sent out earlier[2] (based on upon the examples you sent out) this is essentially what is happening:

1. Flex container is created with flex-direction of column and sets its height to 100px
2. The flex item is created and is told to grow to fill its contents (which is 100px)
3. The div inside can resolve its height of 100% since the flex item knows its height is 100px

I believe you and I are on the same page regarding what should occur in this situation and it currently is what IE/FF do.

[1] http://jsfiddle.net/6LTwU/6/

[2] http://jsfiddle.net/6LTwU/5/

Received on Saturday, 21 June 2014 04:34:01 UTC

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