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From: rbd@lamont.ldgo.columbia.edu (roger davis)
Newsgroups: comp.windows.x
Subject: negative Xlib drawing coordinates
Message-ID: <3644@lamont.ldgo.columbia.edu>
Date: 18 Apr 91 15:25:22 GMT
Organization: Lamont-Doherty Geological Observatory N.Y.
Lines: 22

Is it safe to use negative pixel coordinates as arguments to
Xlib drawing routines, e.g.,

	XDrawLine(dpy, drw, gc, -20, -80, 100, 200);

and does Xlib or the server properly clip such operations at
the boundaries of the drawable? Is this behavior well-defined
for all server/Xlib implementations?

My immediate problem is that I need to draw arbitrarily rotated
rectangles which may be partially off the drawable, and I'd
rather not compute the clipping myself.

I'm hopeful that this is guaranteed to work since the arguments
are not declared as unsigned, but I can't find any explicit mention
of this in any of my FMs. Can anyone in the know comment on this?

Thanks.
-- 
Roger Davis
Lamont-Doherty Geological Observatory
rbd@lamont.ldgo.columbia.edu