[whatwg] [canvas] Proposal for supportsContext

Glenn Maynard glenn at zewt.org
Mon Oct 22 17:31:38 PDT 2012

On Mon, Oct 22, 2012 at 6:36 PM, Ian Hickson <ian at hixie.ch> wrote:

> > If you really want to protect users from the behavior of pages, you'd
> > really need to make creating the context cheap.  For example, don't
> > switch to a high-power GPU until the page actually draws something,
> > and--since many pages use both Canvas and WebGL for one-shot
> > rendering--be sure to switch back to the low-power GPU after some idle
> > time.
> That does seem like a somewhat better implementation strategy, if viable,
> but doesn't preclude the supportsContext() feature.

It doesn't preclude it, but it doesn't seem to fix the problem, either:

> Yes, it could. But we don't control Modernizr or any other scripts people
might use. I'd rather provide something at the browser-level to protect
from bad practice than expect every page to behave nicely.

This (from Dean, the OP) seems to be an argument *against* supportsContext,
since supportsContext is precisely "expecting every page to behave
nicely".  Something-at-the-browser-level is what I described above (in

And if the nicer above fix is implementable, supportsContext seems

Glenn Maynard

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