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Re: [css3-transitions] transitioning to/from auto value

From: Boris Zbarsky <bzbarsky@MIT.EDU>
Date: Wed, 28 Apr 2010 11:21:19 -0400
Message-ID: <4BD8526F.9090005@mit.edu>
To: Brad Kemper <brad.kemper@gmail.com>
CC: Perry Smith <pedzsan@gmail.com>, www-style list <www-style@w3.org>
On 4/28/10 11:07 AM, Brad Kemper wrote:
>>   Is the idea that all change processing needs to complete before sampling the "auto" height the transition should run to?
>
> Wel, yeah.

That's not what your original mail said, though.

>>   The moment such a thing is implemented, people will start demanding that various corner cases "work correctly"
>
> That still sounds better than having a huge number of non-edge cases broken.

 From a UA developer's point of view, no.  It's not.

> On Apr 28, 2010, at 6:55 AM, Boris Zbarsky wrote:
>
>>    var div = document.getElementById("x");
>>    div.style.height = "auto";
>>    div.style.width = "200px";
>>
>> What height should the div transition to and why?  Note that in current UAs those two style changes can be processed in arbitrary order; the page can't detect the difference.
>
> I guess I'll take your word on that, but I find it surprising.

Why?

> I would have thought that they would be processed in the order they were specified.

In Gecko that's not necessarily the case at all.  Note that the key is 
that style changes are coalesced; they are NOT processed when you make 
the .style.whatever change but at some later point in time.

> Couldn't their order be forced when there is a transition involved

Well, one can totally rewrite style change processing, yes....  But 
would that really give the right behavior?  As an author, I wouldn't 
expect behavior to depend on the ordering of the two lines above if a 
transition were to happen in this case.

-Boris
Received on Wednesday, 28 April 2010 15:21:54 GMT

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