More appropriate run loop.

slock.c

@@ -628,11 +628,13 @@ readpw(struct arena *arena,
     struct timeval tv;
     KeySym ksym;
     XEvent ev;
-    unsigned long long last_millis;
+    unsigned long long rendering_timeout_millis;
     struct dpms_state dpms_state;
     struct fonts fonts;
     int error;
 
+    int needs_rendering;
+
     len = 0;
     running = 1;
     failure = 0;
@@ -655,35 +657,35 @@ readpw(struct arena *arena,
     if(!load_fonts(&fonts))
         die("slock: load_fonts\n");
 
-    render_screen(arena,
-                  dpy, locks,
-                  fonts.main_face, fonts.secondary_face,
-                  len);
-    
-    last_millis = millis();
+    needs_rendering = 1;
+
+    rendering_timeout_millis = millis();
+
     while(running) {
         fd_set fds;
         FD_ZERO(&fds);
         FD_SET(xfd, &fds);
         FD_SET(tfd, &fds);
 
-        XFlush(dpy);
-
         update_timerfd(tfd);
 
+        XFlush(dpy);
+
         while(XPending(dpy)) {
             XNextEvent(dpy, &ev);
 
             if(ev.type == MotionNotify) {
+                needs_rendering = 1;
                 dson = 1;
                 set_screen_on(dpy);
             } else if (ev.type == KeyPress) {
                 explicit_bzero(&buf, sizeof(buf));
                 num = XLookupString(&ev.xkey, buf, sizeof(buf), &ksym, 0);
 
+                needs_rendering = 1;
+
                 if(ksym != XK_Escape) {
                     dson = 1;
-                    set_screen_on(dpy);
                 }
 
                 if (IsKeypadKey(ksym)) {
@@ -730,11 +732,6 @@ readpw(struct arena *arena,
                     exit(1);
 #else
                     dson = !dson;
-                    if(dson)
-                        set_screen_on(dpy);
-                    else
-                        set_screen_off(dpy);
-                    continue;
 #endif
                 }
 
@@ -796,34 +793,42 @@ readpw(struct arena *arena,
                 for(screen = 0; screen < nscreens; screen++)
                     XRaiseWindow(dpy, locks[screen]->win);
             }
-
-            /* cap redraw at roughly 30 FPS */
-            if(millis() - last_millis >= 33) {
-                render_screen(arena,
-                              dpy, locks,
-                              fonts.main_face, fonts.secondary_face,
-                              len);
-                last_millis = millis();
-            }
         }
 
-        int ret;
-        if(displaytimeout > 0 && dson) {
-            tv.tv_sec = displaytimeout;
-            tv.tv_usec = 0;
-            ret = select(tfd + 1, &fds, 0, 0, &tv);
-        } else {
-            ret = select(tfd + 1, &fds, 0, 0, 0);
-        }
-        if (ret == 0) {
-            dson = 0;
+        if(dson)
+            set_screen_on(dpy);
+        else
             set_screen_off(dpy);
-        } else if (ret > 0 && FD_ISSET(xfd, &fds)) {
-        } else if (ret > 0 && FD_ISSET(tfd, &fds)) {
-            render_screen(arena,
-                          dpy, locks,
-                          fonts.main_face, fonts.secondary_face,
-                          len);
+
+        render_screen(arena,
+                      dpy, locks,
+                      fonts.main_face, fonts.secondary_face,
+                      len);
+
+        if(millis() - rendering_timeout_millis >= 500) {
+            needs_rendering = 0;
+            rendering_timeout_millis = millis();
+        }
+        
+        int ret;
+        if(needs_rendering) {
+            tv.tv_sec = 0;
+            tv.tv_usec = 33*1000; /* ~30 FPS */
+            ret = select(0, 0, 0, 0, &tv);
+        } else {
+            if(displaytimeout > 0 && dson) {
+                tv.tv_sec = displaytimeout;
+                tv.tv_usec = 0;
+                ret = select(tfd + 1, &fds, 0, 0, &tv);
+            } else {
+                ret = select(tfd + 1, &fds, 0, 0, 0);
+            }
+            if(ret == 0) {
+                dson = 0;
+                set_screen_off(dpy);
+            } else if(ret > 0 && FD_ISSET(xfd, &fds)) {
+            } else if(ret > 0 && FD_ISSET(tfd, &fds)) {
+            }
         }
     }