[whatwg] [canvas] request for {create, get, put}ImageDataHD and ctx.backingStorePixelRatio
Glenn Maynard
glenn at zewt.org
Mon Apr 23 18:50:56 PDT 2012
On Mon, Apr 23, 2012 at 12:43 PM, Darin Fisher <darin at chromium.org> wrote:
> That said, I've come around to being OK with getImageDataHD. As I wrote
> recently, this is because it is possible to implement that in a
> non-blocking fashion. It can just queue up a readback. It only becomes
> necessary to block the calling thread when a pixel is dereferenced. This
> affords developers with an opportunity to instead pass the ImageData off to
> a web worker before dereferencing. Hence, the main thread should not jank
> up. This of course requires developers to be very smart about what they
> are doing, and for browsers to be smart too.
>
It's reasonable to expect users to use async APIs in the main thread;
that's just a part of the platform. It's not reasonable to expect people
to fire up a worker and transfer the buffer to the worker to prevent the
blocking from happening in the main thread. That's a particularly hackish
workaround, not a replacement for an async API.
--
Glenn Maynard
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