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Re: animate/transition height to/from auto

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Mon, 26 Nov 2012 10:13:32 -0800
Message-ID: <CAAWBYDDG8GwzrHUJxro=k2yt73h3JoP72jnPWBiswKBopNnSiw@mail.gmail.com>
To: Rik Cabanier <cabanier@gmail.com>
Cc: Boris Zbarsky <bzbarsky@mit.edu>, www-style list <www-style@w3.org>
On Mon, Nov 26, 2012 at 10:03 AM, Rik Cabanier <cabanier@gmail.com> wrote:
> On Mon, Nov 26, 2012 at 9:36 AM, Tab Atkins Jr. <jackalmage@gmail.com>
> wrote:
>> On Sat, Nov 24, 2012 at 11:10 AM, Rik Cabanier <cabanier@gmail.com> wrote:
>> > I'll correct my previous statement:
>> >
>> > I think transitions should happen with resolved values.
>>
>> You really don't.  "resolved value" is a legacy hack, defined just to
>> make it easier to talk about getComputedStyle().  It's incredibly
>> inconsistent; a handful of properties from 2.1 return their used
>> values, while all other properties return their computed values,
>> including ones that act similarly to 2.1 properties.
>
> I agree about the hack. I got very confused because I assumed that
> 'getComputedStyle' would return the 'computed value'.
> Maybe the css 2.1 spec should change so it no longer uses 'computed value'.
> If someone then talks about 'computed value',  you'd know that they are
> using the obsolete definition.

It's not just 2.1 - we use the term "computed value" *everywhere*,
across all of our specs.  We could change, but it would be a huge cost
- we'd almost certainly have lingering occurrences of the term for a
long time, confusing people, and the switchover itself will confuse
people who know what the word currently means.

> I believe people would want the transition to happen between the values that
> 'getComputedStyle()' returns (whatever that is called).
> This site seems to emulate animation to 'auto' that way:
> http://css-tricks.com/snippets/jquery/animate-heightwidth-to-auto/

I already explained why you do not want to transition between the
resolved value, in the section of my email you quoted and directly
responded to.  It's inconsistent.  You want something else; some way
of using the *used* value of properties, without triggering the
problems that have already been brought up in this thread (children
acting differently based on the value).

~TJ
Received on Monday, 26 November 2012 18:14:21 GMT

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