Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!decwrl!decvax!ucbvax!pasteur!ames!nrl-cmf!cmcl2!brl-adm!umd5!uvaarpa!mcnc!thorin!unc!steele
From: steele@unc.cs.unc.edu (Oliver Steele)
Newsgroups: comp.sys.mac
Subject: Re: (LSC) Deep Dark Secrets Wanted!
Message-ID: <817@thorin.cs.unc.edu>
Date: 22 Jan 88 02:44:33 GMT
References: <870111@hpcilzb.HP.COM>
Sender: news@thorin.cs.unc.edu
Reply-To: steele@unc.UUCP (Oliver Steele)
Organization: University Of North Carolina, Chapel Hill
Lines: 73

tedj@hpcilzb.HP.COM (Ted Johnson) writes:
>
>Would someone please share the DEEP DARK programming secrets on how to:
>	
>	(1)black out the ENTIRE screen (including JCLOCK)?  I have seen several
>           screen savers that do this...  What is the magical ROM routine
>           that I have to call?

There are experts on this on the net, but (deep breath) here goes:
	GrafPort myPort;
	OpenPort(&myPort);	/*does a SetPort too*/
	EraseRect(&myPort.portRect);

This is OK for a stand-alone, MultiFinder-animous application.  If you
want something that will trigger update events when it goes away, try
	Rect bounds;
	bounds = WMgrPort->portRect;
	myWindow = NewWindow(0,&bounds,"\pI may appear on the top screen",
		false,0,-1,false,0);
	ShowWindow(myWindow);
	SetPort(myWindow);
	RectRgn(myWindow.port.visRgn, &bounds);
	EraseRect(&bounds);
	...
	RectRgn(((WindowPeek)myWindow).strucRgn, &bounds);
	DisposeWindow(myWindow);
	DrawMenuBar();
	/* or something like this.  I'm not at home, so I can't
	   try this out */

Remember that if you do some drawing after you black out the screen,
you need to erase the four corners yourself.

Neither of these keeps JCLOCK from doing its thing.  JCLOCK is run off
of the VBL interrupt, and doesn't write into a window, so you need to
  o Disable VBL interrupts.  Nasty.
  o Change ScreenBits to a buffer area.  Nasty.
  o Flip to the alternate screen buffer.  Only works on a Plus and earlier.
  o Change all the colors to black.  Only works on a II (or later? :-)

>	(2)make a DA live forever (i.e., remain active across launching
>           different applications from the non-multi Finder), unless
>           you explicitly close it by clicking on it's close box.
>	   I assume this means patching one or more of the ROM routines....   

Set the DA up to launch a VBL task.  I think da-insect at sumex has
C source for this.

>	(3)Write an INIT?

	main(){SysBeep(7);}
Set the code type to 'INIT', any number.  Build a file called
Beeper.  User ResEdit or FileMaster or some such to change the
type of Beeper to 'INIT'.  Put Beeper in your System Folder.
Set your sound level to something besides 0.  Reboot.  You get the idea.

"The interrupt system, memory manager, and ROM-based I/O drivers have
already been initialized by the ROM boot code.  The boot code initializes
the Event Manager, the Font Manager, the Resource Manager, and the file
system.  (Althought the toolbox is initialized at this point, MacsBug
does not use the Toolbox.)"  This is from the docs for MacsBug, and tells
the state of the world when MacsBug is loaded.  Since INITs are loaded at
about the same time, you're probably safe assuming you have use of the
above managers from an INIT.  Just remember not to use any A5-relative
locations, such as thePort (in InitGraf(&thePort)), but I think the LSC
documentation talks about this.

------------------------------------------------------------------------------
Oliver Steele				  ...!{decvax,ihnp4}!mcnc!unc!steele
							   steele@cs.unc.edu

"What is L-marked?  Theta-marked.  I mean, the mind
 boggles at the idea of a VP being theta-marked!"	-- Gary Hendrick