auto-sync: draw on idle to avoid flicker/tearing

[st.git] / st.c

diff --git a/st.c b/st.c
index 3e48410..2bf133f 100644 (file)
--- a/st.c
+++ b/st.c
@@ -366,7 +366,8 @@ static const char base64_digits[] = {
 char
 base64dec_getc(const char **src)
 {
-       while (**src && !isprint(**src)) (*src)++;
+       while (**src && !isprint(**src))
+               (*src)++;
        return **src ? *((*src)++) : '=';  /* emulate padding if string ends */
 }
 
@@ -664,7 +665,7 @@ die(const char *errstr, ...)
 void
 execsh(char *cmd, char **args)
 {
-       char *sh, *prog;
+       char *sh, *prog, *arg;
        const struct passwd *pw;
 
        errno = 0;
@@ -678,13 +679,20 @@ execsh(char *cmd, char **args)
        if ((sh = getenv("SHELL")) == NULL)
                sh = (pw->pw_shell[0]) ? pw->pw_shell : cmd;
 
-       if (args)
+       if (args) {
                prog = args[0];
-       else if (utmp)
+               arg = NULL;
+       } else if (scroll) {
+               prog = scroll;
+               arg = utmp ? utmp : sh;
+       } else if (utmp) {
                prog = utmp;
-       else
+               arg = NULL;
+       } else {
                prog = sh;
-       DEFAULT(args, ((char *[]) {prog, NULL}));
+               arg = NULL;
+       }
+       DEFAULT(args, ((char *[]) {prog, arg, NULL}));
 
        unsetenv("COLUMNS");
        unsetenv("LINES");
@@ -722,7 +730,7 @@ sigchld(int a)
                die("child exited with status %d\n", WEXITSTATUS(stat));
        else if (WIFSIGNALED(stat))
                die("child terminated due to signal %d\n", WTERMSIG(stat));
-       exit(0);
+       _exit(0);
 }
 
 void
@@ -815,21 +823,26 @@ ttyread(void)
 {
        static char buf[BUFSIZ];
        static int buflen = 0;
-       int written;
-       int ret;
+       int ret, written;
 
        /* append read bytes to unprocessed bytes */
-       if ((ret = read(cmdfd, buf+buflen, LEN(buf)-buflen)) < 0)
-               die("couldn't read from shell: %s\n", strerror(errno));
-       buflen += ret;
+       ret = read(cmdfd, buf+buflen, LEN(buf)-buflen);
 
-       written = twrite(buf, buflen, 0);
-       buflen -= written;
-       /* keep any uncomplete utf8 char for the next call */
-       if (buflen > 0)
-               memmove(buf, buf + written, buflen);
+       switch (ret) {
+       case 0:
+               exit(0);
+       case -1:
+               die("couldn't read from shell: %s\n", strerror(errno));
+       default:
+               buflen += ret;
+               written = twrite(buf, buflen, 0);
+               buflen -= written;
+               /* keep any incomplete UTF-8 byte sequence for the next call */
+               if (buflen > 0)
+                       memmove(buf, buf + written, buflen);
+               return ret;
 
-       return ret;
+       }
 }
 
 void
@@ -2558,6 +2571,7 @@ void
 drawregion(int x1, int y1, int x2, int y2)
 {
        int y;
+
        for (y = y1; y < y2; y++) {
                if (!term.dirty[y])
                        continue;
@@ -2570,7 +2584,7 @@ drawregion(int x1, int y1, int x2, int y2)
 void
 draw(void)
 {
-       int cx = term.c.x;
+       int cx = term.c.x, ocx = term.ocx, ocy = term.ocy;
 
        if (!xstartdraw())
                return;
@@ -2586,9 +2600,11 @@ draw(void)
        drawregion(0, 0, term.col, term.row);
        xdrawcursor(cx, term.c.y, term.line[term.c.y][cx],
                        term.ocx, term.ocy, term.line[term.ocy][term.ocx]);
-       term.ocx = cx, term.ocy = term.c.y;
+       term.ocx = cx;
+       term.ocy = term.c.y;
        xfinishdraw();
-       xximspot(term.ocx, term.ocy);
+       if (ocx != term.ocx || ocy != term.ocy)
+               xximspot(term.ocx, term.ocy);
 }
 
 void