Re: Provide capability in user timing API to mark for user agent events

On 03/11/2015 06:04 AM, Chih-Kai (Patrick) Wang wrote:
> Hi all,
> I am thinking of adding an API in navigator.performance to "ask
> browser to mark when something happens". Currently, user timing API
> provides us with methods to mark in web apps. However, to get more
> accurate mark of specific event, we may need supports from user agent.
> For example, we might care about when is the DOM modification we made in
> Javascript drawn onto screen. Calling to performance.mark() in the
> script is not able to mark when the composition happens. Another way is
> to listen to specific event of the operation, but the event itself takes
> time to propagate to content. For instance, under current multi-process
> architecture Firefox OS, the MozAfterPaint event in content process can
> be fired in up to 80ms after the corresponding composition done in
> parent process.
> The API I'd like to expose might look like:
>    performance.delayedMark('composite', 'done-visually-update');
> which means "set a 'done-visually-update' mark when next composition
> happens".
> Do you have any thought or comment?
My understanding is that the ability to figure out a DOM modification is 
actually being displayed on the screen is tricky and varies greatly 
between the browser engines. Did you look into Frame Timing?


Received on Wednesday, 11 March 2015 18:29:48 UTC