blink: implement 'blink'

main.c

@@ -328,6 +328,7 @@ main(int argc, char *const *argv)
         .auto_margin = true,
         .window_title_stack = tll_init(),
         .flash_timer_fd = timerfd_create(CLOCK_BOOTTIME, TFD_CLOEXEC),
+        .blink_timer_fd = timerfd_create(CLOCK_BOOTTIME, TFD_CLOEXEC),
         .vt = {
             .state = 1,  /* STATE_GROUND */
             .attrs = {
@@ -685,6 +686,7 @@ main(int argc, char *const *argv)
             {.fd = term.ptmx,                     .events = POLLIN},
             {.fd = term.kbd.repeat.pipe_read_fd,  .events = POLLIN},
             {.fd = term.flash_timer_fd,           .events = POLLIN},
+            {.fd = term.blink_timer_fd,           .events = POLLIN},
         };
 
         wl_display_flush(term.wl.display);
@@ -796,6 +798,26 @@ main(int argc, char *const *argv)
             if (term.frame_callback == NULL)
                 grid_render(&term);
         }
+
+        if (fds[4].revents & POLLIN) {
+            uint64_t expiration_count;
+            ssize_t ret = read(
+                term.blink_timer_fd, &expiration_count, sizeof(expiration_count));
+
+            if (ret < 0)
+                LOG_ERRNO("failed to read blink timer");
+            else
+                LOG_DBG("blink timer expired %llu times",
+                        (unsigned long long)expiration_count);
+
+            term.blink_mode = term.blink_mode == BLINK_ON
+                ? BLINK_OFF : BLINK_ON;
+            term_damage_view(&term);
+
+            if (term.frame_callback == NULL)
+                grid_render(&term);
+        }
+
     }
 
 out:
@@ -885,6 +907,8 @@ out:
 
     if (term.flash_timer_fd != -1)
         close(term.flash_timer_fd);
+    if (term.blink_timer_fd != -1)
+        close(term.blink_timer_fd);
 
     if (term.ptmx != -1)
         close(term.ptmx);

render.c

@@ -3,6 +3,7 @@
 #include <string.h>
 #include <sys/ioctl.h>
 #include <sys/time.h>
+#include <sys/timerfd.h>
 
 #include <wayland-cursor.h>
 #include <xdg-shell.h>
@@ -117,6 +118,9 @@ render_cell(struct terminal *term, struct buffer *buf, const struct cell *cell,
         _bg = swap;
     }
 
+    if (cell->attrs.blink && term->blink_mode == BLINK_OFF)
+        _fg = _bg;
+
     struct rgb fg = color_hex_to_rgb(_fg);
     struct rgb bg = color_hex_to_rgb(_bg);
 
@@ -128,6 +132,20 @@ render_cell(struct terminal *term, struct buffer *buf, const struct cell *cell,
     cairo_rectangle(buf->cairo, x, y, width, height);
     cairo_fill(buf->cairo);
 
+    if (cell->attrs.blink && !term->is_blinking) {
+        /* First cell we see that has blink set - arm blink timer */
+        LOG_DBG("arming blink timer");
+        struct itimerspec alarm = {
+            .it_value = {.tv_sec = 0, .tv_nsec = 500 * 1000000},
+            .it_interval = {.tv_sec = 0, .tv_nsec = 500 * 1000000},
+        };
+
+        if (timerfd_settime(term->blink_timer_fd, 0, &alarm, NULL) < 0)
+            LOG_ERRNO("failed to arm blink timer");
+        else
+            term->is_blinking = true;
+    }
+
     if (cell->c[0] == '\0' || cell->attrs.conceal)
         return;
 
@@ -365,7 +383,39 @@ grid_render(struct terminal *term)
         row->dirty = false;
         all_clean = false;
 
-        wl_surface_damage_buffer(term->wl.surface, 0, r * term->cell_height, term->width, term->cell_height);
+        wl_surface_damage_buffer(
+            term->wl.surface,
+            0, r * term->cell_height,
+            term->width, term->cell_height);
+    }
+
+    if (term->is_blinking) {
+        /* Check if there are still any visible blinking cells */
+        bool none_is_blinking = true;
+        for (int r = 0; r < term->rows; r++) {
+            struct row *row = grid_row_in_view(term->grid, r);
+            for (int col = 0; col < term->cols; col++) {
+                if (row->cells[col].attrs.blink) {
+                    none_is_blinking = false;
+                    break;
+                }
+            }
+        }
+
+        /* No, disarm the blink timer */
+        if (none_is_blinking) {
+            LOG_DBG("disarming blink timer");
+
+            term->is_blinking = false;
+            term->blink_mode = BLINK_ON;
+
+            if (timerfd_settime(
+                    term->blink_timer_fd, 0,
+                    &(struct itimerspec){0}, NULL)  < 0)
+            {
+                LOG_ERRNO("failed to disarm blink timer");
+            }
+        }
     }
 
     /* TODO: break out to function */

terminal.h

@@ -246,6 +246,10 @@ struct terminal {
     bool flash_active;
     int flash_timer_fd;
 
+    bool is_blinking;
+    enum { BLINK_ON, BLINK_OFF } blink_mode;
+    int blink_timer_fd;
+
     struct vt vt;
     struct kbd kbd;