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From: fry@huma1.HARVARD.EDU (David Fry)
Newsgroups: comp.sys.mac
Subject: Re: Delphi digest volume 3, issue 36
Message-ID: <2640@husc6.UUCP>
Date: Mon, 3-Aug-87 18:15:12 EDT
Article-I.D.: husc6.2640
Posted: Mon Aug  3 18:15:12 1987
Date-Received: Tue, 4-Aug-87 05:40:15 EDT
Sender: news@husc6.UUCP
Reply-To: fry@huma1.UUCP (David Fry)
Distribution: world
Organization: Harvard Math Department
Lines: 52

>From: JIMH
>Subject: changing pixel depth
>Date: 25-JUL 01:47 Macintosh II

>Does anyone know how the monitor cdev cause the desktop (or any
>programs) to redraw themselve with the new screen depth?  I want a fkey
>to toggle between 1 and 8 bit mode.  It pretty straightforward to set
>the mode to whatever depth you need and when you r elaunch the finder
>(return to finder you have new depth set. what is less straightforward
>is to get the desktop to draw itself without a launch.  best jim

I've been using this method with success. It assumes a menu
bar is present, but I guess you'd have to check that.

	menuBar = GetMenuBar();
	ClearMenuBar();
	
	bigPtr = &bigPort;
	OpenCPort(bigPtr);
	EraseRect(&bigPtr->portRect);  
    /* this opens and erases a screen-sized port */

	PenMode(patCopy);
	PaintRect(&bigPtr->portRect);
    /* this paints everything black */

	CloseCPort(bigPtr);

	theRgn = GetGrayRgn();
    /* this function is defined in the latest
       Lightspeed C release, but you can access 
       the global variable GrayRgn if you don't have
       LSC  */
	PaintOne(NULL,theRgn);

	SetMenuBar(menuBar);
	DrawMenuBar();
	DisposHandle(menuBar);

	temp = FrontWindow();
	while ( temp != NULL ) {
		PaintOne((CWindowPeek)temp,((CWindowPeek)temp)->strucRgn);
	    /* this fixes up all the windows */
		temp = ((CWindowPeek)temp)->nextWindow;
		} 

	/* we're done! */

David Fry				fry@huma1.harvard.EDU
Department of Mathematics		fry@harvma1.bitnet
Harvard University			...!harvard!huma1!fry
Cambridge, MA  02138