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Re: Mutation events replacement

From: Ojan Vafai <ojan@chromium.org>
Date: Tue, 5 Jul 2011 17:51:38 -0700
Message-ID: <CANMdWTstNz+JfCtPE_=c-j7nQJtxRV73B9AAapipy6Let1Aueg@mail.gmail.com>
To: Ryosuke Niwa <rniwa@webkit.org>
Cc: Rafael Weinstein <rafaelw@google.com>, Olli@pettay.fi, Aryeh Gregor <Simetrical+w3c@gmail.com>, Adam Klein <adamk@google.com>, Jonas Sicking <jonas@sicking.cc>, Anne van Kesteren <annevk@opera.com>, Webapps WG <public-webapps@w3.org>
On Tue, Jul 5, 2011 at 5:36 PM, Ryosuke Niwa <rniwa@webkit.org> wrote:

> On Tue, Jul 5, 2011 at 5:27 PM, Rafael Weinstein <rafaelw@google.com>wrote:
>> It seems like these are rarified enough cases that visual artifacts
>> are acceptable collateral damage if you do this. [Put another way, if
>> you care enough about the visual polish of your app that you will put
>> energy into avoiding flickr, you probably aren't using alert and
>> showModalDialog anyway].
>> Also, it's up to the app when to do it, so it's entirely in its
>> control (and thus avoid visual artifacts).
> Given that we don't provide an API to control paint in general, I'm not
> convinced that we should add such a requirement in the DOM mutation event
> spec.

Many of the use-cases for mutation events (e.g. model-driven views) are
poorly met if we don't give some assurances here.

>  Note that this is a problem with both proposals. Work done in (at
>> least some) mutation observers is delayed. If a sync paint occurs
>> before it, it's work won't be reflected on the screen.
> Right.  Maybe we can add a note saying that the user agents are recommended
> not to paint before all mutation observers are called.  I don't think we
> should make this a requirement.

There may be a middle ground that isn't so hard to for browser vendors
implement interoperably. Can we require no repaint except in the presence of
a specific list synchronous API calls? I'm sure that's too simplistic, but
I'm hoping someone with more experience can chime in with something that
might actually be a plausible requirement.

- Ryosuke
Received on Wednesday, 6 July 2011 00:52:22 UTC

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