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Re: [whatwg] OffscreenCanvas from a worker and synchronization with DOM/CSS

From: Elliott Sprehn <esprehn@chromium.org>
Date: Sat, 23 Jan 2016 14:40:19 -0500
Message-ID: <CAO9Q3iKH3xmmzO0F6Vm9OL2=8Q1=647vZKSrftFUqV=ftUSeig@mail.gmail.com>
To: Gregg Tavares <gman@chromium.org>
Cc: WHAT Working Group <whatwg@whatwg.org>
I presume you're supposed to just postMessage back to the main thread when
you commit(). The spec should probably have a "commit" event though.
On Jan 23, 2016 1:49 PM, "Gregg Tavares" <gman@chromium.org> wrote:

> I just noticed Firefox shipped an OffscreenCanvas implementation. Looking
> at the spec it seems there is no way to synchronize updates from a worker
> with dom/css manipulations.
>
> Was this already discussed? There are web apps that synchronize HTML dom
> elements with canvas updates. I'm sure they'd all love to gain the benefits
> of being able to render to their canvas from a worker. But, if they can't
> synchronize the canvas update with their DOM element position updates there
> will be unacceptable skewing/judder/issues
>
> Maybe it was already decided but I couldn't find the discussion. It seems
> like a pretty bold thing to do for HTML because it basically encourages
> using as little HTML/DOM/CSS as possible rather than encouraging just doing
> some fancy rendering in a worker and the rest in HTML.
>
> A few example of apps that would love to get the benefit of offscreen
> rendering in a worker but could not without some way to synchronize
>
>     Apple Maps
>     https://youtu.be/bBs3sqH27Kk
>
>     Baidu Maps
>     https://youtu.be/dT-k-xI5UYw
>
>     Yahoo Japan Maps
>     https://youtu.be/DYVEILUCRZQ
>
> Worse, those things that could have been HTML but are no longer HTML can't
> be used in standard ways. For example because Yahoo Japan's Maps use HTML a
> translation extension, Rikaikun, is able to provide translations. The
> current OffscreenCanvas spec effectively discourages using HTML elements in
> these cases making features like these impossible.
>
>     Rakaikun on Yahoo Japan Maps
>     https://youtu.be/sQ68V8ggwB0
>
> Another example which would seem really relevant to WebVR is to allow
> various parts of a scene to be presented as a fully functional web page
> like this example
>
>
>
> http://learningthreejs.com/blog/2013/04/30/closing-the-gap-between-html-and-webgl/
>
> but that won't work if you can't synchronize dom and offscreencanvas.
>
Received on Saturday, 23 January 2016 19:40:49 UTC

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