Re: [CSSOM] Revisiting transforms and getBoundingClientRect()

On Sep 8, 2011, at 10:03 AM, Erik Arvidsson wrote:

> On Wed, Sep 7, 2011 at 22:34, Robert O'Callahan <robert@ocallahan.org> wrote:
>> It would be difficult to expose a synchronous "onlayout" event to Web
>> content safely, and it would be pointless to make it asynchronous.
> 
> I don't think it would be pointless to have an async event that would
> be dispatched when we know that the layout is non dirty at some point
> before the next paint. At this point getting the layout rects would be
> cheap.
> 
> I agree that exposing a sync layout event sounds scary. Hello sync
> mutation events!
> 
> For debugging purpose I would love to have a way to "blow up" if a
> layout is happening when I don't expect it. This is definitely
> something the Firebug and Web Inspector could expose and does not need
> any standardization but I do think it requires cooperation from the
> code.

WebKit's web inspector does expose this, via the "Timeline" panel. It even tells you how long those layouts took.

Simon