On Thu, 10 Dec 2009 22:36:45 +0100, Oliver Hunt <oli...@apple.com> wrote:
Ideally if we were to have a graphics context in a worker we'd want it
to be the standard CanvasRenderingContext2D, the only real problem is
that CanvasRenderingContext2D references the parent canvas element which
clearly won't fly in a worker.
I think the solution to that is to just as with Navigator be more creative
with IDL interfaces. The methods that take HTMLImageElement or
HTMLVideoElement similarly should be excluded from the
CanvasRenderingContext2D exposed within Web Workers.
I've been thinking of creating something like a WorkerCanvas which is
basically a DOM-less CanvasRenderingContext2D, so you can do
var canvas = new WorkerCanvas(width, height);
canvas.putImageData(myData);
Something like that sounds good, though shouldn't putImageData() be on the
2D context you can get via WorkerCanvas?
I have a vague desire to allow a ImageData to be provided as a backing
store, but then you may hit perf or consistency issues on UAs that use
premultiplied alpha backing stores.
Additionally there's the question of origin tainting -- is it possible
to taint the origin in a worker? you don;t have image elements, you
can't xhr unsafely to other origins, but maybe i'm missing something?
<canvas> can only be tainted by unsafe <img> or <video> elements. Neither
is applicable, so no.
--
Anne van Kesteren
http://annevankesteren.nl/
