I think "opaque" vs. "alpha: false" is a matter of opinion. The functionality doesn't change, regardless of what you call it.
I agree with Gregg that this really should be implemented to reflect the functionality that WebGL already has. Wether 2D or 3D, there's a lot of common ground between the various canvas contexts and it doesn't make much sense to reinvent the wheel when one context type has already implemented the functionality. --Brandon On Wed, Mar 13, 2013 at 1:02 PM, Maciej Stachowiak <[email protected]> wrote: > > An attribute on the canvas element would presumably be equally applicable > to all contexts. Is there a reason that it's better to have opaqueness > specified at context creation time instead of on the canvas? Also, I think > "opaque" is easier to understand than "alpha: false". > > - Maciej > > On Mar 13, 2013, at 9:57 AM, Gregg Tavares <[email protected]> wrote: > > It would be nice if this was the same as WebGL instead of different. > Especially because 2d canvas and WebGL need to inter-operate in the near > future. > > In WebGL to create a canvas with no alpha (an opaque canvas) you do this > > gl = canvas.getContext("experimental-webgl", { alpha: false }); > > Why can't 2D canvas be this > > ctx = canvas.getContext("2d", {alpha: false}); > > As for why this is important to be the same see the proposal for Canvas in > Workers here (http://wiki.whatwg.org/wiki/CanvasInWorkers) > > In that proposal the "backingstore" of a canvas can be moved to/from a > worker. That solution may or many not be the final solution but it points > out that whatever solution is chosen we need the solution to work for both > canvas 2d and WebGL and as such needs a common way to create backing stores > with no alpha. > > > > On Wed, Mar 13, 2013 at 9:30 AM, Dirk Schulze <[email protected]> wrote: > >> This is a very long thread and I did not see any conclusions or agreement >> on this thread. Can you summarize the topic and the status on the >> acceptance level please? >> >> Greetings, >> Dirk >> >> On Mar 13, 2013, at 9:15 AM, Stephen White <[email protected]> >> wrote: >> >> > Hi WebKittens, >> > >> > I'm planning to implement the canvas "opaque" attribute, as proposed >> here: >> http://lists.w3.org/Archives/Public/public-whatwg-archive/2013Mar/0109.html >> . >> > >> > This is an attribute that causes the allocation of an opaque backing >> store for <canvas>, allowing optimizations at the time the canvas is >> composited into the page, such as disabling blending and culling obscured >> content. It is based on the moz-opaque attribute currently shipping in >> Firefox. >> > >> > I'll be placing the feature behind the build-time flag >> ENABLE(OPAQUE_CANVAS). >> > >> > Let me know if you have any comments or concerns. >> > >> > Stephen >> > _______________________________________________ >> > webkit-dev mailing list >> > [email protected] >> > https://lists.webkit.org/mailman/listinfo/webkit-dev >> >> _______________________________________________ >> webkit-dev mailing list >> [email protected] >> https://lists.webkit.org/mailman/listinfo/webkit-dev >> > > _______________________________________________ > webkit-dev mailing list > [email protected] > https://lists.webkit.org/mailman/listinfo/webkit-dev > > > > _______________________________________________ > webkit-dev mailing list > [email protected] > https://lists.webkit.org/mailman/listinfo/webkit-dev > >
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