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

Re: [css3-transitions] Transitions from display:none

From: Boris Zbarsky <bzbarsky@MIT.EDU>
Date: Fri, 13 Jan 2012 15:39:50 -0500
Message-ID: <4F109696.8060909@mit.edu>
To: "Tab Atkins Jr." <jackalmage@gmail.com>
CC: Sylvain Galineau <sylvaing@microsoft.com>, "www-style@w3.org" <www-style@w3.org>
On 1/13/12 3:22 PM, Tab Atkins Jr. wrote:
> No, it doesn't.  If the adblocker wants to know an image's size, it
> will *request* the image's size.  *That* is an operation that requires
> up-to-date layout information.  Setting the src of an image might
> trigger an adblocker's operation, but it does not, itself, require any
> layout info to complete.

My point is that you, as the spec writer, can't require that the act of 
setting an image src not trigger an ad blocker.

>> You seem to think that text input values are simpler than they really are...
>> they're not.
>
> I do not understand at all how the style engine is involved in
> changing the value of an input.  Enlighten me?

<shrug>.  I'm happy to paste a bunch of C++ here if you want if you 
don't want to take my word for it.  The short is that if values can be 
stored in multiple places and shuffled lazily (say between the element 
and the CSS box, which is what you see on screen), then the 
implementation can allow temporary inconsistent states which can only be 
resolved by making sure the set of CSS boxes is up to date, which 
involves computing style.

> (The only thing I can think of is if it's considered similar to a DOM mutation.)

Well, it certainly _is_ that in Gecko. Trusted code can even touch that 
DOM inside the text input.  I was leaving that out, because that's a 
whole separate kettle of worms.

> Yes, I'd like to do so.  It makes sense to me to base this timing off
> of the flush points (specifying when flush points occur)

I don't think this is feasible.

> but there
> may be a better place to do so, like "at the end of the current task"
> (the hook used for the new mutation events).

Or perhaps off the same timing source that requestAnimationFrame runs from?

-Boris
Received on Friday, 13 January 2012 23:25:36 GMT

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