patch: appsync

x.c

@@ -1936,6 +1936,9 @@ resize(XEvent *e)
 	cresize(e->xconfigure.width, e->xconfigure.height);
 }
 
+int tinsync(uint);
+int ttyread_pending();
+
 void
 run(void)
 {
@@ -1970,7 +1973,7 @@ run(void)
 		FD_SET(ttyfd, &rfd);
 		FD_SET(xfd, &rfd);
 
-		if (XPending(xw.dpy))
+		if (XPending(xw.dpy) || ttyread_pending())
 			timeout = 0;  /* existing events might not set xfd */
 
 		seltv.tv_sec = timeout / 1E3;
@@ -1984,7 +1987,8 @@ run(void)
 		}
 		clock_gettime(CLOCK_MONOTONIC, &now);
 
-		if (FD_ISSET(ttyfd, &rfd))
+		int ttyin = FD_ISSET(ttyfd, &rfd) || ttyread_pending();
+		if (ttyin)
 			ttyread();
 
 		xev = 0;
@@ -2008,7 +2012,7 @@ run(void)
 		 * maximum latency intervals during `cat huge.txt`, and perfect
 		 * sync with periodic updates from animations/key-repeats/etc.
 		 */
-		if (FD_ISSET(ttyfd, &rfd) || xev) {
+		if (ttyin || xev) {
 			if (!drawing) {
 				trigger = now;
 				drawing = 1;
@@ -2019,6 +2023,18 @@ run(void)
 				continue;  /* we have time, try to find idle */
 		}
 
+		if (tinsync(su_timeout)) {
+			/*
+			 * on synchronized-update draw-suspension: don't reset
+			 * drawing so that we draw ASAP once we can (just after
+			 * ESU). it won't be too soon because we already can
+			 * draw now but we skip. we set timeout > 0 to draw on
+			 * SU-timeout even without new content.
+			 */
+			timeout = minlatency;
+			continue;
+		}
+
 		/* idle detected or maxlatency exhausted -> draw */
 		timeout = -1;
 		if (blinktimeout && tattrset(ATTR_BLINK)) {