[whatwg] Offscreen canvas (or canvas for web workers).

Jonas Sicking jonas at sicking.cc
Mon Feb 22 15:10:52 PST 2010

On Mon, Feb 22, 2010 at 11:13 AM, David Levin <levin at google.com> wrote:
> I've talked with some other folks on WebKit (Maciej and Oliver) about having
> a canvas that is available to workers. They suggested some nice
> modifications to make it an offscreen canvas, which may be used in the
> Document or in a Worker.

What is the use case for this? It seems like in most cases you'll want
to display something on screen to the user, and so the difference
comes down to shipping drawing commands across the pipe, vs. shipping
the pixel data.

The other use case I can think of is doing image manipulation and then
sending the result directly to the server, without ever displaying it
to the user. However this is first of all not supported by the
suggested API, and second I can't think of any image manipulation that
you wouldn't want to display to the user except for scaling down a
high resolution image. But that seems like a much simpler API than all
of canvas. And again, not even this simple use case is supported by
the current API.

/ Jonas

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