Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!vsi1!apple!bloom-beacon!EXPO.LCS.MIT.EDU!rws
From: rws@EXPO.LCS.MIT.EDU (Bob Scheifler)
Newsgroups: comp.windows.x
Subject: Re: Help needed with GC's
Message-ID: <8901141509.AA05645@EXPIRE.LCS.MIT.EDU>
Date: 14 Jan 89 15:09:33 GMT
References: <8937@burdvax.PRC.Unisys.COM>
Sender: daemon@bloom-beacon.MIT.EDU
Organization: The Internet
Lines: 10


    What I want to know is what is quickest way to swap the foreground and
    background pixels of a given rectangle that works on both monochrome and
    color monitors?

When only two pixel values are involved, A and B, you can either
set the function to GXinvert and the plane mask to (A xor B) and
the foreground to all ones, or you can set the function to GXxor
and the foreground to (A xor B) and the plane mask to all ones.
Which one is faster will probably depend on the server.