Re: [AD] set_difference_blender patch

[Peter W. <nov...@gm...>]

On 2011-01-30, Jon Rafkind <wo...@cc...> wrote:
> Anyone mind if I apply this patch to set_difference_blender for 4.4? It
> clamps the lowest value to 0 instead of using ABS to wrap around. Heres
> a post on a.cc that no one responded to:
> http://www.allegro.cc/forums/thread/606235
> 
> I can add an example program if someone wants.

The relevant change log entry is: 

+   3.9.17: Burton Radons changed the truecolor pixel blending functions to 
+   use a single callback function rather than the previous table. This may 
+   break some old code, but should remain largely backward compatible, and 
+   the new way is much more flexible. He also added a more complete set of 
+   blender functions, including Photoshop modes like burn, difference, 
+   lumincance, etc.

I don't have Photoshop, but if GIMP implements the same thing then your
patch would appear to be correct.

Peter