Fix status bar flicker by double-buffering the output.

Add a bar struct to contain the properties of each bar.

Eliminate redundant calls to set the bar colors.

ok marco

diff --git a/spectrwm.c b/spectrwm.c
index 8916331..1115cac 100644 (file)
--- a/spectrwm.c
+++ b/spectrwm.c
@@ -331,6 +331,12 @@ struct swm_geometry {
 struct swm_screen;
 struct workspace;
 
+struct swm_bar {
+       Window                  id;
+       Pixmap                  buffer;
+       struct swm_geometry     g;
+};
+
 /* virtual "screens" */
 struct swm_region {
        TAILQ_ENTRY(swm_region) entry;
@@ -338,7 +344,7 @@ struct swm_region {
        struct workspace        *ws;    /* current workspace on this region */
        struct workspace        *ws_prior; /* prior workspace on this region */
        struct swm_screen       *s;     /* screen idx */
-       Window                  bar_window;
+       struct swm_bar          *bar;
 };
 TAILQ_HEAD(swm_region_list, swm_region);
 
@@ -1331,8 +1337,6 @@ bar_print(struct swm_region *r, const char *s)
        size_t                  len;
        XRectangle              ibox, lbox;
 
-       XClearWindow(display, r->bar_window);
-
        len = strlen(s);
        XmbTextExtents(bar_fs, s, len, &ibox, &lbox);
 
@@ -1351,9 +1355,21 @@ bar_print(struct swm_region *r, const char *s)
        if (x < SWM_BAR_OFFSET)
                x = SWM_BAR_OFFSET;
 
-       DRAWSTRING(display, r->bar_window, bar_fs, r->s->bar_gc,
+       /* clear back buffer */
+       XSetForeground(display, r->s->bar_gc, r->s->c[SWM_S_COLOR_BAR].color);
+       XFillRectangle(display, r->bar->buffer, r->s->bar_gc, 0, 0,
+           WIDTH(r->bar), HEIGHT(r->bar));
+
+       /* draw back buffer */
+       XSetForeground(display, r->s->bar_gc,
+           r->s->c[SWM_S_COLOR_BAR_FONT].color);
+       DRAWSTRING(display, r->bar->buffer, bar_fs, r->s->bar_gc,
            x, (bar_fs_extents->max_logical_extent.height - lbox.height) / 2 -
            lbox.y, s, len);
+
+       /* blt */
+       XCopyArea(display, r->bar->buffer, r->bar->id, r->s->bar_gc, 0, 0,
+           WIDTH(r->bar), HEIGHT(r->bar), 0, 0);
 }
 
 void
@@ -1688,6 +1704,8 @@ bar_fmt_print(void)
 
        for (i = 0; i < ScreenCount(display); i++) {
                TAILQ_FOREACH(r, &screens[i].rl, entry) {
+                       if (r->bar == NULL)
+                               continue;
                        bar_fmt(fmtexp, fmtnew, r, sizeof fmtnew);
                        bar_replace(fmtnew, fmtrep, r, sizeof fmtrep);
                        bar_print(r, fmtrep);
@@ -1735,14 +1753,17 @@ bar_toggle(struct swm_region *r, union arg *args)
 
        DNPRINTF(SWM_D_BAR, "bar_toggle\n");
 
-       if (bar_enabled)
+       if (bar_enabled) {
                for (i = 0; i < sc; i++)
                        TAILQ_FOREACH(tmpr, &screens[i].rl, entry)
-                               XUnmapWindow(display, tmpr->bar_window);
-       else
+                               if (tmpr->bar)
+                                       XUnmapWindow(display, tmpr->bar->id);
+       } else {
                for (i = 0; i < sc; i++)
                        TAILQ_FOREACH(tmpr, &screens[i].rl, entry)
-                               XMapRaised(display, tmpr->bar_window);
+                               if (tmpr->bar)
+                                       XMapRaised(display, tmpr->bar->id);
+       }
 
        bar_enabled = !bar_enabled;
 
@@ -1790,11 +1811,13 @@ bar_refresh(void)
        bzero(&wa, sizeof wa);
        for (i = 0; i < ScreenCount(display); i++)
                TAILQ_FOREACH(r, &screens[i].rl, entry) {
+                       if (r->bar == NULL)
+                               continue;
                        wa.border_pixel =
                            screens[i].c[SWM_S_COLOR_BAR_BORDER].color;
                        wa.background_pixel =
                            screens[i].c[SWM_S_COLOR_BAR].color;
-                       XChangeWindowAttributes(display, r->bar_window,
+                       XChangeWindowAttributes(display, r->bar->id,
                            CWBackPixel | CWBorderPixel, &wa);
                }
        bar_update();
@@ -1806,13 +1829,15 @@ bar_setup(struct swm_region *r)
        char                    *default_string;
        char                    **missing_charsets;
        int                     num_missing_charsets = 0;
-       int                     i, x, y;
+       int                     i;
 
        if (bar_fs) {
                XFreeFontSet(display, bar_fs);
                bar_fs = NULL;
        }
 
+       if ((r->bar = calloc(1, sizeof(struct swm_bar))) == NULL)
+               err(1, "bar_setup: calloc: failed to allocate memory.");
 
        DNPRINTF(SWM_D_BAR, "bar_setup: loading bar_fonts: %s\n", bar_fonts);
 
@@ -1845,18 +1870,27 @@ bar_setup(struct swm_region *r)
        if (bar_height < 1)
                bar_height = 1;
 
-       x = X(r);
-       y = bar_at_bottom ? (Y(r) + HEIGHT(r) - bar_height) : Y(r);
+       X(r->bar) = X(r);
+       Y(r->bar) = bar_at_bottom ? (Y(r) + HEIGHT(r) - bar_height) : Y(r);
+       WIDTH(r->bar) = WIDTH(r) - 2 * bar_border_width;
+       HEIGHT(r->bar) = bar_height - 2 * bar_border_width;
 
-       r->bar_window = XCreateSimpleWindow(display,
-           r->s->root, x, y, WIDTH(r) - 2 * bar_border_width,
-           bar_height - 2 * bar_border_width,
+       r->bar->id = XCreateSimpleWindow(display,
+           r->s->root, X(r->bar), Y(r->bar), WIDTH(r->bar), HEIGHT(r->bar),
            bar_border_width, r->s->c[SWM_S_COLOR_BAR_BORDER].color,
            r->s->c[SWM_S_COLOR_BAR].color);
-       XSelectInput(display, r->bar_window, VisibilityChangeMask);
+
+       r->bar->buffer = XCreatePixmap(display, r->bar->id, WIDTH(r->bar),
+           HEIGHT(r->bar), DefaultDepth(display, r->s->idx));
+
+       XSelectInput(display, r->bar->id, VisibilityChangeMask);
+
        if (bar_enabled)
-               XMapRaised(display, r->bar_window);
-       DNPRINTF(SWM_D_BAR, "bar_setup: bar_window: 0x%lx\n", r->bar_window);
+               XMapRaised(display, r->bar->id);
+
+       DNPRINTF(SWM_D_BAR, "bar_setup: window: 0x%lx, (x,y) w x h: (%d,%d) "
+           "%d x %d\n", WINID(r->bar), X(r->bar), Y(r->bar), WIDTH(r->bar),
+           HEIGHT(r->bar));
 
        if (signal(SIGALRM, bar_signal) == SIG_ERR)
                err(1, "could not install bar_signal");
@@ -1864,6 +1898,17 @@ bar_setup(struct swm_region *r)
 }
 
 void
+bar_cleanup(struct swm_region *r)
+{
+       if (r->bar == NULL)
+               return;
+       XDestroyWindow(display, r->bar->id);
+       XFreePixmap(display, r->bar->buffer);
+       free(r->bar);
+       r->bar = NULL;
+}
+
+void
 drain_enter_notify(void)
 {
        int                     i = 0;
@@ -6891,7 +6936,7 @@ visibilitynotify(XEvent *e)
        if (e->xvisibility.state == VisibilityUnobscured)
                for (i = 0; i < ScreenCount(display); i++)
                        TAILQ_FOREACH(r, &screens[i].rl, entry)
-                               if (e->xvisibility.window == r->bar_window)
+                               if (e->xvisibility.window == WINID(r->bar))
                                        bar_update();
 }
 
@@ -7007,7 +7052,7 @@ new_region(struct swm_screen *s, int x, int y, int w, int h)
                        if (r->ws->r != NULL)
                                r->ws->old_r = r->ws->r;
                        r->ws->r = NULL;
-                       XDestroyWindow(display, r->bar_window);
+                       bar_cleanup(r);
                        TAILQ_REMOVE(&s->rl, r, entry);
                        TAILQ_INSERT_TAIL(&s->orl, r, entry);
                }
@@ -7078,7 +7123,7 @@ scan_xrandr(int i)
        /* remove any old regions */
        while ((r = TAILQ_FIRST(&screens[i].rl)) != NULL) {
                r->ws->old_r = r->ws->r = NULL;
-               XDestroyWindow(display, r->bar_window);
+               bar_cleanup(r);
                TAILQ_REMOVE(&screens[i].rl, r, entry);
                TAILQ_INSERT_TAIL(&screens[i].orl, r, entry);
        }
@@ -7229,12 +7274,10 @@ setup_screens(void)
                setscreencolor("black", i + 1, SWM_S_COLOR_BAR);
                setscreencolor("rgb:a0/a0/a0", i + 1, SWM_S_COLOR_BAR_FONT);
 
-               /* create graphics context on screen with default font color */
-               screens[i].bar_gc = XCreateGC(display, screens[i].root, 0,
-                   &gcv);
-
-               XSetForeground(display, screens[i].bar_gc,
-                   screens[i].c[SWM_S_COLOR_BAR_FONT].color);
+               /* create graphics context on screen */
+               gcv.graphics_exposures = 0;
+               screens[i].bar_gc = XCreateGC(display, screens[i].root,
+                   GCGraphicsExposures, &gcv);
 
                /* set default cursor */
                XDefineCursor(display, screens[i].root,
@@ -7404,11 +7447,9 @@ main(int argc, char *argv[])
        }
 noconfig:
 
-       /* load conf (if any) and refresh font color in bar graphics contexts */
-       if (cfile && conf_load(cfile, SWM_CONF_DEFAULT) == 0)
-               for (i = 0; i < ScreenCount(display); ++i)
-                       XSetForeground(display, screens[i].bar_gc,
-                           screens[i].c[SWM_S_COLOR_BAR_FONT].color);
+       /* load conf (if any) */
+       if (cfile)
+               conf_load(cfile, SWM_CONF_DEFAULT);
 
        setup_ewmh();
        /* set some values to work around bad programs */