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From: ado@elsie.nci.nih.gov (Arthur David Olson)
Newsgroups: comp.protocols.time.ntp
Subject: xclock :-)
Message-ID: <90392@elsie.nci.nih.gov>
Date: 5 Dec 90 04:33:46 GMT
Organization: NIH/NCI/LEC, Bethesda, MD
Lines: 91

So now that you've got your system's clock within milliseconds of where you
want it to be, what about the display on your screen?  The attached is only a
start; the ftime system call would be needed for a complete job, along with
the code to lead the time by the delay between when the xclock process sends
the bits and when bits appear on screen.

				--ado

< From ado Tue Dec  4 23:20:23 1990
< To: xbugs@expo.lcs.mit.edu
< Subject: xclock -analog can be up to a minute behind (with fix)
< Cc:  adam@ncifcrf.gov
< 
< 
< 			  X Window System Bug Report
< 			    xbugs@expo.lcs.mit.edu
< 
< 
< 
< 
< VERSION:
< 	XV11R4 (plus fixes through fix-14)
< 
< CLIENT MACHINE and OPERATING SYSTEM:
< 	Sun 3/60 running SunOS 4.0.3
< 
< DISPLAY:
< 	Sun CG4
< 
< WINDOW MANAGER:
< 	twm
< 
< AREA:
< 	xclock
< 
< SYNOPSIS:
< 	An analog xclock can be up to a minute behind.
< 
< DESCRIPTION:
< 	It rounds time down to the nearest minute; if it does an update at,
< 	say, 59 seconds past the minute, you lose.
< 
< 
< REPEAT BY:
< 	At 50 seconds past the minute, start up an
< 		xclock -analog -geom 300x300+1+1
< 	and note the position of the hands
< 
< SAMPLE FIX:
< mit/lib/Xaw/SCCS/s.Clock.c: 1.2 vs. 1.3
< *** 1.2/mit/lib/Xaw/Clock.c	Tue Dec  4 23:18:10 1990
< --- 1.3/mit/lib/Xaw/Clock.c	Tue Dec  4 23:18:11 1990
< ***************
< *** 379,385 ****
< 			     */
< 			    DrawHand(w,
< 				w->clock.minute_hand_length, w->clock.hand_width,
< ! 				((double) tm.tm_min)/60.0
< 			    );
< 			    if(w->clock.Hdpixel != w->core.background_pixel)
< 				XFillPolygon( dpy,
< --- 379,385 ----
< 			     */
< 			    DrawHand(w,
< 				w->clock.minute_hand_length, w->clock.hand_width,
< ! 				(tm.tm_min * 60.0 + tm.tm_sec) / (60.0 * 60.0)
< 			    );
< 			    if(w->clock.Hdpixel != w->core.background_pixel)
< 				XFillPolygon( dpy,
< ***************
< *** 394,401 ****
< 			    w->clock.hour = w->clock.segbuffptr;
< 			    DrawHand(w, 
< 				w->clock.hour_hand_length, w->clock.hand_width,
< ! 				((((double)tm.tm_hour) + 
< ! 				    (((double)tm.tm_min)/60.0)) / 12.0)
< 			    );
< 			    if(w->clock.Hdpixel != w->core.background_pixel) {
< 			      XFillPolygon(dpy,
< --- 394,401 ----
< 			    w->clock.hour = w->clock.segbuffptr;
< 			    DrawHand(w, 
< 				w->clock.hour_hand_length, w->clock.hand_width,
< ! 				(((tm.tm_hour * 60.0) + tm.tm_min) * 60.0 +
< ! 				tm.tm_sec) / (12.0 * 60.0 * 60.0)
< 			    );
< 			    if(w->clock.Hdpixel != w->core.background_pixel) {
< 			      XFillPolygon(dpy,
< -- 
< 		Arthur David Olson	ado@elsie.nci.nih.gov
< 		ADO and Elsie are Ampex and Borden trademarks