Re: [css-display]? Compositing, expensive things, and laziness

On Fri, May 10, 2013 at 7:20 AM, Ali Juma <ajuma@chromium.org> wrote:
> On Thu, May 9, 2013 at 11:34 PM, Robert O'Callahan <robert@ocallahan.org>
> wrote:
>> On Thu, May 9, 2013 at 8:23 PM, Tab Atkins Jr. <jackalmage@gmail.com>
>> wrote:
>>> Right, but as soon as the animation triggers, and starts its expensive
>>> paint, unrelated rAF timers will hitch as well.
>>
>> I'm a bit confused. If you're painting on the main thread, any attempt to
>> paint the content could cause delays in the firing some some rAF callback.
>> If you're not painting on the main thread, none of this matters. Are you
>> painting it on the main thread with the ability to interrupt painting to
>> return to the event loop?
>
> This is with painting off the main the thread, but it still matters. While
> the main thread is free to fire rAF callbacks and process scroll updates, we
> still need to get the resulting changes to the screen. Without a way to
> indicate that the expensive content should be handled in a special way, the
> painting thread cannot know that it should give the other content higher
> priority and provide the painted tiles for the other content to the
> compositor before the expensive content's tiles are ready (note that this is
> different from what we would normally do: we usually want the compositor to
> have a coherent set of tiles, so that if the page is, say, alternating
> between all-red and all-green, the compositor never produces a half-red
> half-green frame).

Further thoughts, roc?  This thread accidentally died.  ^_^

~TJ

Received on Thursday, 23 May 2013 18:18:28 UTC