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From: ari@eleazar.dartmouth.edu (Ari Halberstadt)
Newsgroups: comp.sys.mac.programmer
Subject: How to get the QD globals outside of an application
Message-ID: <18350@dartvax.Dartmouth.EDU>
Date: 6 Jan 90 19:59:51 GMT
Sender: news@dartvax.Dartmouth.EDU
Organization: Dartmouth College, Hanover, NH
Lines: 42

Several people have been curious about how to access the QuickDraw
globals from within an XCMD or XFCN. Here's a little routine
I wrote for THINK C which you can call when you initialize your
XCMD or XFCN. If I remember correctly, MPW uses a single global
structure to store the QuickDraw globals. Thus, one
BlockMove would suffice to implement this routine
in MPW.

/* QuickDraw global offsets off of A5 */
#define THEPORT 		0			/* GrafPtr */
#define WHITE			THEPORT-8	/* Pattern */
#define BLACK			WHITE-8		/* Pattern */
#define GRAY			BLACK-8		/* Pattern */
#define LTGRAY			GRAY-8		/* Pattern */
#define DKGRAY			LTGRAY-8	/* Pattern */
#define ARROW			DKGRAY-68	/* Cursor */
#define SCREENBITS		ARROW-14	/* BitMap */
#define RANDSEED		SCREENBITS-4 /* long */

/* Setup the QuickDraw globals by getting them from their offsets off of A5 */
/* By Ari Halberstadt, 1990 */
static void
SetupQDGlobals()
{
	Ptr	p;
	
	p = *((Ptr *) CurrentA5);
	thePort = (GrafPtr) (THEPORT + p);
	BlockMove(WHITE + p, white, sizeof(Pattern));
	BlockMove(BLACK + p, black, sizeof(Pattern));
	BlockMove(GRAY + p, gray, sizeof(Pattern));
	BlockMove(LTGRAY + p, ltGray, sizeof(Pattern));
	BlockMove(DKGRAY + p, dkGray, sizeof(Pattern));
	BlockMove(ARROW + p, &arrow, sizeof(Cursor));
	BlockMove(SCREENBITS + p, &screenBits, sizeof(BitMap));
	randSeed = (long) (RANDSEED + p); /*I hope this line is correct...*/
}

--

Ari Halberstadt '91, "Long live succinct signatures"
ari@eleazar.dartmouth.edu	Disclaimer: "Live Free or Die"