[whatwg] Enabling LCD Text and antialiasing in canvas

Rik Cabanier cabanier at gmail.com
Wed Mar 13 19:36:51 PDT 2013

On Wed, Mar 13, 2013 at 11:48 AM, Gregg Tavares <gman at google.com> wrote:

> Sorry for only mentioning this so late but is there any chance to steer
> this to be more inline with WebGL?
> WebGL already has the option to have an opaque canvas using context
> creation parameters. In WebGL it's
>    gl = canvas.getContext("webgl", {alpha: false});
> If we go forward with an "opaque" attribute now you have 2 conflicting
> settings.
>    canvas.opaque = true;
>    gl = canvas.getContext("webgl", {alpha: true});
> Who wins that conflict? Yea, I know we could come up with rules. (&& the 2
> settings, etc...)
> But, there are other context creation attributes we'd like to see on a 2d
> canvas. One that comes to mind is 'preserveDrawingBuffer'.
> preserveDrawingBuffer: false in WebGL means that the canvas is double
> buffered. This is a performance win since most browsers using GPU
> compositing need to copy the contents of the canvas when compositing.
> Setting preseverDrawingBuffer: false (which is the default in WebGL) means
> the browser can double buffer and avoid the copy. We'd like to see that
> same attribute for 2D canvas/contexts to get the same perf benefit for
> canvas games, etc.
> So, given we want more creation attributes and given WebGL already has a
> way to declare opaqueness why not follow the existing method and add
> context creation parameters to 2d canvas to solve this issue rather than
> make a new and conflicting 'opaque' attribute?

It seems that we should follow the path that WebGL followed so it's not
confusing for authors.

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