Newsgroups: comp.sys.next
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From: patl@athena.mit.edu (Patrick J. LoPresti)
Subject: A simple question or two
Message-ID: <1991Apr11.212629.25773@athena.mit.edu>
Summary: How do I draw with a Mac-like transfer mode? Whence "trap #2"?
Sender: news@athena.mit.edu (News system)
Organization: Massachusetts Institute of Technology
Date: Thu, 11 Apr 91 21:26:29 GMT
Lines: 21

I want to draw a line across a View so that black pixels along the line
become white and white pixels along the line become black.  In other
words, I want an XOR transfer mode for my pen.  I don't care what
happens to shades of gray.

I have waded through both NeXT and Adobe documentation, but have found
no way to do this.  The closest I have seen is the NX_XOR compositing
option, but that relies on transparency, and the image in my View is
entirely opaque.

What if I want to move a bitmap onto the screen with an XOR transfer
mode?  How about AND?  Does the NeXT paradigm support such Mac-like
things?

Second Question:  Someone posted a while ago that the assembly
instruction "trap #2" flushes the 68040 instruction (data?) cache on the
NeXT.  Where is this documented?  What do the other traps do?

Please respond by Email,
Pat
 "Questions are a burden to others; answers a prison for oneself."