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From: zaccone@shire.cs.psu.edu
Newsgroups: comp.sys.mac.programmer
Subject: mouse down in grow box
Keywords: mouse down grow box
Message-ID: <1989Oct6.113511.3400@psuvax1.cs.psu.edu>
Date: 6 Oct 89 11:35:11 GMT
Sender: news@psuvax1.cs.psu.edu
Reply-To: zaccone@shire.cs.psu.edu ()
Organization: Penn State University
Lines: 26


The Macintosh Programming Primer contains a program called the Event
Tutor.  Here is how the program handles a mouse down event in the grow
box.  The code makes sense to me, except that I don't understand the
purpose of the GetPort and SetPort function calls.  I've tried taking
them out to convince myself that they are necessary, but I still don't
understand why they are needed.  Can someone explain this to a Mac
programming novice?


case inGrow:
    windSize = GrowWindow( whichWindow, gTheEvent.where, &gSizeRect );
    if (windSize != 0 ){
        GetPort( &oldPort );
        SetPort( whichWindow );
        EraseRect( &whichWindow->portRect );
        SizeWindow( whichWindow, LoWord( windSize ), HiWord( windSize ),
                    NORMAL_UPDATES );
        InvalRect( &whichWindow->portRect);
        SetPort( oldPort );
    }
    break;

Rick Zaccone
zaccone@bknlvms.bitnet
zaccone@sol.bucknell.edu