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[whatwg] canvas context "alpha" attribute

From: Rik Cabanier <cabanier@gmail.com>
Date: Wed, 12 Mar 2014 02:04:47 -0700
Message-ID: <CAGN7qDCUYH=t9fyFNASQ16AFpChWENpq3Rq+Gz1XEGTY5TkZ1A@mail.gmail.com>
To: "whatwg@whatwg.org" <whatwg@whatwg.org>
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]

1: http://wiki.whatwg.org/wiki/CanvasOpaque
2: http://crbug.com/234297
4: https://groups.google.com/forum/#!topic/mozilla.dev.platform/5i8H-xKGtEg
5: https://bugzilla.mozilla.org/show_bug.cgi?id=982480
Received on Wednesday, 12 March 2014 09:05:38 UTC

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