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From: rs4u#@ANDREW.CMU.EDU (Richard Siegel)
Newsgroups: comp.sys.mac
Subject: Re: QuickDraw Request
Message-ID: <MS.V3.17.rs4u.80020d16.dunmore.ibm032.616.1@andrew.cmu.edu>
Date: Sun, 16-Nov-86 20:33:22 EST
Article-I.D.: andrew.MS.V3.17.rs4u.80020d16.dunmore.ibm032.616.1
Posted: Sun Nov 16 20:33:22 1986
Date-Received: Mon, 17-Nov-86 02:04:30 EST
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: University of California at Berkeley
Lines: 32


[Line-Eater? What line-eater? *chomp* 8-)]

SetRect and OffsetRect are two entirely different operations.

SetRect fills the fields of a rectangle with values, to initialize it. If you
try to use OffsetRect on an uninitialized rectangle, you get garbage. 

OffsetRect is useful for moving a rectangle by a certain distance
horizontally and/or vertically; the same thing could be achieved by adding
the offsets into all fields of your rectangle:

	{
		r.top += voffset;
		r.bottom += voffset;
		r.left += hoffset;
		 r.right += hoffset;
	}


 I would suspect that OffsetRect does much the same thing, so the efficiency
gain by using OffsetRect versus the above 4 lines of code is minimal, if
there is anything. 

To rehash: use SetRect to initialize a rectangle (or you could fill the
fields by hand, it's only a difference in readability. To move a rectangle,
use either OffsetRect (for readability), or else use those 4 lines of code
above...

Hope this helps out.

		--Rich