6 files changed, 83 insertions(+), 9 deletions(-)

M README.md
M config.def.h
M config.h
M st.c
M st.info
M x.c

@@ 18,7 18,8 @@ This is a custom suckless st build (credits to lukesmith's build for ligatures p
 - newterm
 - anysize
 - anygeometry
-- xresources 
+- xresources
+- sync patch ( Better draw timing to reduce flicker/tearing and improve animation smoothness )
 - live reload ( change colors/fonts on the fly )
   and more...
   <br>

@@ 52,6 52,12 @@ static double minlatency = 8;
 static double maxlatency = 33;
 
 /*
+ * Synchronized-Update timeout in ms
+ * https://gitlab.com/gnachman/iterm2/-/wikis/synchronized-updates-spec
+ */
+static uint su_timeout = 200;
+
+/*
  * blinking timeout (set to 0 to disable blinking) for the terminal blinking
  * attribute.
  */

@@ 5,8 5,8 @@
  *
  * font: see http://freedesktop.org/software/fontconfig/fontconfig-user.html
  */
-static char *font = "JetBrainsMono Nerd Font:style:medium :pixelsize=15:antialias=true:autohint=true";
-static char *font2[] = { "JetBrainsMono Nerd Font:style:medium :pixelsize=15:antialias=true:autohint=true" };
+static char *font = "JetBrainsMono Nerd Font :pixelsize=15:antialias=true:autohint=true";
+static char *font2[] = { "JetBrainsMono Nerd Font :pixelsize=15:antialias=true:autohint=true" };
 static int borderpx = 0;
 
 /*


@@ 52,6 52,12 @@ static double minlatency = 8;
 static double maxlatency = 33;
 
 /*
+ * Synchronized-Update timeout in ms
+ * https://gitlab.com/gnachman/iterm2/-/wikis/synchronized-updates-spec
+ */
+static uint su_timeout = 200;
+
+/*
  * blinking timeout (set to 0 to disable blinking) for the terminal blinking
  * attribute.
  */

@@ 247,6 247,33 @@ static uchar utfmask[UTF_SIZ + 1] = {0xC0, 0x80, 0xE0, 0xF0, 0xF8};
 static Rune utfmin[UTF_SIZ + 1] = {       0,    0,  0x80,  0x800,  0x10000};
 static Rune utfmax[UTF_SIZ + 1] = {0x10FFFF, 0x7F, 0x7FF, 0xFFFF, 0x10FFFF};
 
+#include <time.h>
+static int su = 0;
+struct timespec sutv;
+
+static void
+tsync_begin()
+{
+	clock_gettime(CLOCK_MONOTONIC, &sutv);
+	su = 1;
+}
+
+static void
+tsync_end()
+{
+	su = 0;
+}
+
+int
+tinsync(uint timeout)
+{
+	struct timespec now;
+	if (su && !clock_gettime(CLOCK_MONOTONIC, &now)
+	       && TIMEDIFF(now, sutv) >= timeout)
+		su = 0;
+	return su;
+}
+
 ssize_t
 xwrite(int fd, const char *s, size_t len)
 {


@@ 835,6 862,9 @@ ttynew(char *line, char *cmd, char *out, char **args)
 	return cmdfd;
 }
 
+static int twrite_aborted = 0;
+int ttyread_pending() { return twrite_aborted; }
+
 size_t
 ttyread(void)
 {


@@ 844,10 874,10 @@ ttyread(void)
 	int ret;
 
 	/* append read bytes to unprocessed bytes */
-	if ((ret = read(cmdfd, buf+buflen, LEN(buf)-buflen)) < 0)
+	if ((ret = twrite_aborted ? 1 : read(cmdfd, buf+buflen, LEN(buf)-buflen)) < 0)
 		die("couldn't read from shell: %s\n", strerror(errno));
-	buflen += ret;
-
+    
+	buflen += twrite_aborted ? 0 : ret;
 	written = twrite(buf, buflen, 0);
 	buflen -= written;
 	/* keep any uncomplete utf8 char for the next call */


@@ 1010,6 1040,7 @@ tsetdirtattr(int attr)
 void
 tfulldirt(void)
 {
+	tsync_end();
 	tsetdirt(0, term.row-1);
 }
 


@@ 2008,6 2039,12 @@ strhandle(void)
 		return;
 	case 'P': /* DCS -- Device Control String */
 		term.mode |= ESC_DCS;
+		/* https://gitlab.com/gnachman/iterm2/-/wikis/synchronized-updates-spec */
+		if (strstr(strescseq.buf, "=1s") == strescseq.buf)
+			tsync_begin(), term.mode &= ~ESC_DCS;  /* BSU */
+		else if (strstr(strescseq.buf, "=2s") == strescseq.buf)
+			tsync_end(), term.mode &= ~ESC_DCS;  /* ESU */
+		return;
 	case '_': /* APC -- Application Program Command */
 	case '^': /* PM -- Privacy Message */
 		return;


@@ 2633,6 2670,9 @@ twrite(const char *buf, int buflen, int show_ctrl)
 	Rune u;
 	int n;
 
+	int su0 = su;
+	twrite_aborted = 0;
+
 	for (n = 0; n < buflen; n += charsize) {
 		if (IS_SET(MODE_UTF8) && !IS_SET(MODE_SIXEL)) {
 			/* process a complete utf8 char */


@@ 2643,6 2683,10 @@ twrite(const char *buf, int buflen, int show_ctrl)
 			u = buf[n] & 0xFF;
 			charsize = 1;
 		}
+		if (su0 && !su) {
+			twrite_aborted = 1;
+			break;  // ESU - allow rendering before a new BSU
+		}
 		if (show_ctrl && ISCONTROL(u)) {
 			if (u & 0x80) {
 				u &= 0x7f;

@@ 193,6 193,7 @@ st| simpleterm,
 	Ms=\E]52;%p1%s;%p2%s\007,
 	Se=\E[2 q,
 	Ss=\E[%p1%d q,
+	Sync=\EP=%p1%ds\E\\,
 
 st-256color| simpleterm with 256 colors,
 	use=st,

@@ 2003,6 2003,9 @@ resize(XEvent *e)
 	cresize(e->xconfigure.width, e->xconfigure.height);
 }
 
+int tinsync(uint);
+int ttyread_pending();
+
 void
 run(void)
 {


@@ 2037,7 2040,7 @@ 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;


@@ 2051,7 2054,8 @@ 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;


@@ 2075,7 2079,7 @@ 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;


@@ 2086,6 2090,18 @@ 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)) {