Path: utzoo!mnetor!tmsoft!torsqnt!jarvis.csri.toronto.edu!rutgers!usc!apple!agate!shelby!csli!wilson
From: wilson@csli.Stanford.EDU (Nathan Wilson)
Newsgroups: comp.sys.mac.programmer
Subject: Problems with Inits and Trap patches
Message-ID: <10403@csli.Stanford.EDU>
Date: 19 Sep 89 22:15:28 GMT
Sender: wilson@csli.Stanford.EDU (Nathan Wilson)
Distribution: comp.sys.mac.programmer
Organization: Center for the Study of Language and Information, Stanford U.
Lines: 139

I'm trying to write my first Init/Trap patch and am having a problem.
I've got the init part working.  In addition if I call GetTrapAddress
before and after the call to SetTrapAddress they differ and the new
address is the one I expect it to be.  Finally, if I run an
application version of the code, the initial call to GetTrapAddress
returns the same address as I used in the SetTrapAddress the Init.
All this seem to be fine and wonderful, except there is no change in
the behavior of the trap.  The complete code for MPW 3.0 follows.  In
addition to comments on the bug I would be happy to get any stylistic
comments people care to make.  FYI, the ultimate goal of this is to
have an init for multi-screen systems that patches the ZoomWindow call
so it will zoom to the screen containing the center of the window
rather than the "main" screen.  This is suggested by IM-V but isn't
implemented.  Does anyone know why?  The system I'm working on is a
MacIIcx with 8 meg of RAM, TMON installed, running MultiFinder,
PowerStation, and assorted inits.

	Thanks in advance,
			Nathan Wilson
			Teleos Research
			nathan%teleos.com@ai.sri.com


Here's the code for the Init part:

***** File ZoomMain.p *****

Unit ZoomMain;

Interface

Uses Memtypes,QuickDraw,OSIntf,ToolIntf,Packages;

Procedure LoadNewZoomWindow;

Implementation

Procedure MacsBugPrint( theMesg : Str255 );  inline $ABFF;

Procedure LoadNewZoomWindow;
const
	rsrcNum = 0;
	zoomID = $A83A;
var
	aZoomProc : Handle;
	aStr : Str255;
	
begin
	SysBeep( 30 );
	SetZone( SystemZone );
	aZoomProc := GetResource( 'Zoom', rsrcNum );
	if ResError <> noErr then SysBeep( 30 );
	DetachResource( aZoomProc );
	if ResError <> noErr then SysBeep( 30 );
	HLock( aZoomProc );
	NumToString( GetTrapAddress( zoomID ), aStr );
	MacsbugPrint( aStr );
	NumToString( LongInt( StripAddress( aZoomProc^ ) ), aStr );
	MacsbugPrint( aStr );
	SetTrapAddress( LongInt( StripAddress( aZoomProc^ ) ), zoomID );
	NumToString( GetTrapAddress( zoomID ), aStr );
	MacsbugPrint( aStr );
end;

end. {Unit}

***** End File ZoomMain.p

And the code in Zoom resource is just:

***** File ZoomFunc.p *****

Unit ZoomInit;

Interface

Uses Memtypes,QuickDraw,OSIntf,ToolIntf,Windows;

Procedure MyZoomWindow( theWindow: WindowPtr; partCode: Integer; front: Boolean);

Implementation

Procedure MyZoomWindow( theWindow: WindowPtr; partCode: Integer; front: Boolean);
begin
	Sysbeep( 30 );
end;

end. {Unit}

***** End File ZoomFunc.p *****

and the makefile is:

***** File Makefile *****

ZoomInit D ZoomFunc ZoomMain ZoomInit.r
	Rez ZoomInit.r -t INIT -c 'Zoom' -o ZoomInit

ZoomFunc D ZoomFunc.p.o
	Link -rt Zoom=0 6
		-ra =16 6
		-m MYZOOMWINDOW 6
		ZoomFunc.p.o 6
		-o ZoomFunc

ZoomMain D ZoomMain.p.o
	Link -rt INIT=0 6
		-ra =16 6
		-m LOADNEWZOOMWINDOW 6
		ZoomMain.p.o 6
		"{Libraries}"Interface.o 6
		-o ZoomMain
	
ZoomAppl D ZoomFunc ZoomMain.p.o ZoomInit.r
	Link ZoomMain.p.o 6
		-m LOADNEWZOOMWINDOW 6
		"{Libraries}"Interface.o 6
		"{PLibraries}"PasLib.o 6
		-o ZoomAppl
	Rez ZoomAppl.r -c 'Zoom' -o ZoomInit -append

***** End File Makefile *****

finally the .r files are:

***** File ZoomInit.r *****

include "ZoomFunc";
include "ZoomMain";

***** End File ZoomInit.r *****

and

***** File ZoomAppl.r *****

include "ZoomFunc";

***** End File ZoomAppl.r *****