[whatwg] [canvas] globalCompositeOperation poorly defined

L. David Baron dbaron at dbaron.org
Fri Jul 21 09:07:53 PDT 2006

On Friday 2006-07-21 11:14 +0300, Henri Sivonen wrote:
> I gather that a normative reference to the Porter–Duff paper is needed:
> http://keithp.com/~keithp/porterduff/p253-porter.pdf

Perhaps, assuming that's what's been implemented, although that would
only define 10 of the 12 operators in the spec.  But that paper doesn't
define binary operators for 'darker' and 'lighter', which seem to be
among the less-interoperable right now.  (It defines a unary 'darken'
operator over a space of numeric parameters.)


L. David Baron                                <URL: http://dbaron.org/ >
           Technical Lead, Layout & CSS, Mozilla Corporation
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