On Mon, 10 Sep 2012 13:14:30 -0500, Dean Jackson <d...@apple.com> wrote:
To give a real world example, the popular tool Modernizr tests for the
availability of WebGL by attempting to create a WebGL context. This can
happen
even on pages that have no intention of using WebGL - an author has just
inserted Modernizr into their page and is using it to test for another
feature.
As I said, creating a context is not a free operation. In fact, on
shipping
Safari (Mountain Lion) this causes us to switch to a more powerful GPU
on systems that have two graphics processors.
An alternative (for the WebGL case) would be to have the author test for
the
presence of window.WebGLRenderingContext. However, this is not reliable.
This is actually what Modernizr does these days [1], but older versions
did in fact create the context.
[1]
https://github.com/Modernizr/Modernizr/blob/master/modernizr.js#L429-436
--
Mike Taylor
Opera Software
