Composite Quesiton

[Jonathan Morton]

On Mon, 2010-05-17 at 17:39 +0800, Huang, FrankR wrote:
>             You can imagine the result of this test. I attached the
> result of this application. I can understand the green part , but for
> the black part, I have no idea. Is it all solid to black???

The (src IN mask) part essentially modifies the "input" side of the
equation to a green-black pattern, actually a (1,0,1,0) to (0,0,0,0)
ARGB vector pattern.  Using the SRC operator then causes this to be
literally copied to the destination.

If you want the mask to limit the area of influence of the green,
producing a green-white result rather than a green-black pattern, you
need to use the OVER operator.

If you want the mask to extend beyond the 20x20 square, you need to set
the Repeat property on it as well as the source.

-- 
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From: Jonathan Morton
      jonathan.morton at movial.com