[cairo] Simplifying the operator set

[Bill Spitzak]

On Thursday 06 January 2005 10:45 pm, Carl Worth wrote:
>                 "A atop B is the union of A in B and B out A"
>                 "A xor B is the union of A out B and B out A".

Actually they are the *sum* of the component operations.

The word "union" implies to me the "A+B-AB" operation, ie what happens to the 
alpha in "over" and in many of the photoshop style operators.

-- 
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     /\_       _|_========___         Bill Spitzak
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