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Re: [css-compositing] Request to move Compositing and Blending spec to CR

From: James Robinson <jamesr@google.com>
Date: Wed, 11 Dec 2013 18:57:02 -0800
Message-ID: <CAD73md+=Yjeicj=UwDrcGy2W=dgV1xYV9DHWBTEWGLRMe9WOmg@mail.gmail.com>
To: Rik Cabanier <cabanier@gmail.com>
Cc: www-style list <www-style@w3.org>, "public-fx@w3.org" <public-fx@w3.org>, www-svg <www-svg@w3.org>
On Wed, Dec 11, 2013 at 6:44 PM, Rik Cabanier <cabanier@gmail.com> wrote:

>> Canvas is defined in HTML.  Having text here to define a behavior that
>> canvas does not use is just confusing with no upside.
> No, canvas refers to the compositing spec for the 'globalComposite'
> operator [1]:
> The globalCompositeOperation attribute sets the current composition
> operator, which controls how shapes and images are drawn onto the scratch
> bitmap<http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#scratch-bitmap>,
> once they have had globalAlpha<http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#dom-context-2d-globalalpha> and
> the current transformation matrix applied. The possible values are those
> defined in the Compositing and Blending specification. [COMPOSITE]<http://www.whatwg.org/specs/web-apps/current-work/multipage/references.html#refsCOMPOSITE>
> Do you think the canvas spec should be more clear that compositing is
> defined in the "Compositing and Blending specification"?

The paragraph in question -  "9.2.3. Clip to self behavior" - describes a
behavior that is not used by canvas, or (from what you've said) by anything
in the Compositing and Blending spec.  What value does it have other than
creating confusion, in that case?

- James
Received on Thursday, 12 December 2013 02:57:30 UTC

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