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[css3-flexbox] Some references to "flex basis" should be replaced with "hypothetical main size"

From: Daniel Holbert <dholbert@mozilla.com>
Date: Tue, 05 Jun 2012 14:38:18 -0700
Message-ID: <4FCE7C4A.40708@mozilla.com>
To: www-style@w3.org
Just noticed one issue in the flexbox spec:

Section 9.7. "Resolving Flexible Lengths" tells us to do math with the
flex basis, even though our flex basis may be a keyword like "auto" or
"fit-content", which we can't do math with.

In particular, there are three mentions of "flex basis", quoted below:
   # If the flexibility is positive
   [...]
   #   Set the item's main size to its flex basis plus a fraction
   #   of the free space proportional to the ratio.
and...
   # If the flexibility is negative
   #   For every item on the line, multiply its flex shrink ratio
   #   by its flex basis, [...]  Set the item's main size to its
   #   flex basis minus a fraction of the free space [...]

http://dev.w3.org/csswg/css3-flexbox/#resolve-flexible-lengths

These mathematical operations are meaningless when the flex basis is a
keyword like e.g. "auto", "fit-content"  (or really when it's any
indefinite size),

I think this chunk of spec really wants to refer to the "hypothetical
main size", which is a definite length value that's derived from the
(possibly-keyword-valued) flex basis in Section 9.2.

Correct?

Thanks,
~Daniel
Received on Tuesday, 5 June 2012 21:38:46 GMT

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