[whatwg] Adding blending to the canvas API

[Jeremy Apthorp]

On Wed, Apr 11, 2012 at 4:05 PM, Rik Cabanier <cabanier at gmail.com> wrote:

> All,
>
> I'm working on a spec to add blending and compositing through simple CSS
> keywords. It is trying to define a generic model that is not specific to
> Canvas, HTML or SVG and then lists how the model could be implemented.
> We've gotten some comments that this feature would be useful in Canvas as
> well so I was wondering if it made sense to add it to the canvas API.
>
> I can see 2 ways of adding this:
> 1. extend the list of compositing operators (
>
> http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html#compositing
> )
> with blending. This is what is currently in the draft spec (
> https://dvcs.w3.org/hg/FXTF/rawfile/tip/compositing/index.html chapter 7)
>
> 2. create a new attribute on the context called 'globalBlendOperation' that
> takes the same list of blend operations as css (
> https://dvcs.w3.org/hg/FXTF/rawfile/tip/compositing/index.html#blend-mode)
>
> Any thoughts?
>

This seems much more useful than the existing composite operations :)