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Re: [css3-transforms] Effect of CSS transforms on scrollable areas

From: Øyvind Stenhaug <oyvinds@opera.com>
Date: Thu, 31 May 2012 15:42:45 +0200
To: www-style@w3.org
Message-ID: <op.we6dpjgmbunlto@oyvinds-desktop>
On Thu, 31 May 2012 06:52:21 +0200, Sebastian Zartner  
<sebastianzartner@gmx.de> wrote:

>> On Thu, May 31, 2012 at 11:31 AM, Robert O'Callahan
>> <robert@ocallahan.org>wrote:

>> > http://people.mozilla.org/~roc/test_transform_scrollable_area.html

>> I've updated the testcase. Now if you hover over the animated element
>> while
>> it's animating, you can observe changes to the result of
>> getBoundingClientRect during the animation. Curiously, changes to the
>> scrollbar state are still not reflected until the end of the animation.
>>
>> I don't think we should spec the details of that mess. However, I don't
>> know what to do instead.
>
> I believe what Opera and Firefox do here is what the user would expect.  
> Why shouldn't the scrollable area be affected by an animation? Imagine  
> the animated object being completely outside of the scrollable container  
> for a longer animation and you're not able to scroll to it. Wouldn't  
> that be annoying?

I agree, it sounds like a WebKit bug. Can't reproduce it in Chromium 18 on  
Ubuntu 10.04, though.

Spec seems reasonably clear: "[...] the extent of the overflow area takes  
into account transformed elements. This behavior is similar to what  
happens when elements are offset via relative positioning. Therefore, if  
the value of the ‘overflow’ property is ‘scroll’ or ‘auto’, scrollbars  
will appear as needed to see content that is transformed outside the  
visible area."

-- 
Øyvind Stenhaug
Core Norway, Opera Software ASA
Received on Thursday, 31 May 2012 13:43:17 GMT

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