W3C home > Mailing lists > Public > www-style@w3.org > November 2012

Re: animate/transition height to/from auto

From: Boris Zbarsky <bzbarsky@MIT.EDU>
Date: Fri, 23 Nov 2012 22:49:01 -0500
Message-ID: <50B043AD.4090401@mit.edu>
To: Rik Cabanier <cabanier@gmail.com>
CC: www-style@w3.org
On 11/23/12 10:33 PM, Rik Cabanier wrote:
> I guess it depends. In Chrome (WebKit?) the computed style inspector
> says '100px'

The "computed style" inspector is reporting what getComputedStyle 
returns, which is the CSS2 "computed value" for the 'height', not the 
current "computed value".  Nowadays what it's returning is called the 
"used value".  See http://dev.w3.org/csswg/cssom/#resolved-value for the 
gory details.

> The spec says (1):

Indeed.  The computed value is "auto" here.

> I don't believe it is possible to implement the desired behavior for
> this particular case.

My point is that this is not an edge case.  This sort of thing is the 
common case for "auto", because "auto" heights are affected by so many 
factors and because they affect so many things around them differently 
than do fixed heights.

> There are going to be many edge cases and possible
> recursion problems that will be very hard to crack.

Yes, agree.

> A simply rule (= used the computed value) is much easier to understand
> and can give the desired effect.

No, it can't. The computed value here is "auto".  Now again, what should 
"0.3*0 + 0.7*auto" evaluate to, exactly?

Received on Saturday, 24 November 2012 03:49:29 UTC

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