[whatwg] [canvas] globalCompositeOperation poorly defined

[Henri Sivonen]

On Jul 21, 2006, at 00:59, L. David Baron wrote:

> On Friday 2006-06-23 12:30 +0200, Arve Bersvendsen wrote:
>> There are a number of tests for globalCompositeOperation here:
>>
>> <URL:http://testsuite.org/html/elements/canvas/getContext/2d/ 
>> globalCompositeOperation/>
>>
>> These tests are written pretty much to the letter of the  
>> specification,
>> but it would be appreciated if someone tried to verify the tests.
>
> I don't see how the pass conditions in those tests are derived from  
> the
> little that the specification says.  If someone could explain, perhaps
> they could write better text for the specification?

I gather that a normative reference to the Porter–Duff paper is needed:
http://keithp.com/~keithp/porterduff/p253-porter.pdf

-- 
Henri Sivonen
hsivonen at iki.fi
http://hsivonen.iki.fi/