[whatwg] canvas context "alpha" attribute

Ian Hickson ian at hixie.ch
Wed Mar 12 10:49:56 PDT 2014

On Wed, 12 Mar 2014, Rik Cabanier wrote:
> About a year ago, Google and mozilla proposed the "alpha" attribute as an
> option when you create the canvas context. The wiki explains the feature
> very well. [1]
> Since then, Google has implemented and shipped this [2][3]. There is a
> proposal to implement [4] and a patch [5] for firefox.
> An author can "feature test" by setting alpha to false and reading a pixel
> in the context. If the pixel comes back with an alpha of 0, it means that
> it is not supported.
> Could this be added to the HTML specification? [6]

It's being tracked here:


It's awaiting interest from a second vendor. It's not clear to me from the 
Mozilla bug whether Mozilla engineers actually support this.

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'

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