Don't use poll timeout for timing animation.
Receiving events breaks out of the poll and resets the time out.
Effectively, this blocks the animation when the client receives events.
As a quick fix, use timerfd for timing the animation.
diff --git a/flower.c b/flower.c
index 4654de0..46deb05 100644
--- a/flower.c
+++ b/flower.c
@@ -5,6 +5,8 @@
#include <i915_drm.h>
#include <sys/ioctl.h>
#include <sys/poll.h>
+#include <sys/timerfd.h>
+#include <time.h>
#include <fcntl.h>
#include <unistd.h>
#include <math.h>
@@ -151,9 +153,10 @@
int fd, i, ret;
uint32_t name, mask;
cairo_surface_t *s;
- struct pollfd p[1];
-
- srandom(time(NULL));
+ struct pollfd p[2];
+ struct timespec ts;
+ struct itimerspec its;
+ uint64_t expires;
fd = open(gem_device, O_RDWR);
if (fd < 0) {
@@ -171,6 +174,24 @@
surface = wl_display_create_surface(display);
+ p[1].fd = timerfd_create(CLOCK_MONOTONIC, 0);
+ if (p[1].fd < 0) {
+ fprintf(stderr, "could not create timerfd\n: %m");
+ return -1;
+ }
+
+ p[1].events = POLLIN;
+ clock_gettime(CLOCK_MONOTONIC, &ts);
+ its.it_value = ts;
+ its.it_interval.tv_sec = 0;
+ its.it_interval.tv_nsec = 20 * 1000000;
+ if (timerfd_settime(p[1].fd, TFD_TIMER_ABSTIME, &its, NULL) < 0) {
+ fprintf(stderr, "could not set timerfd\n: %m");
+ return -1;
+ }
+
+ srandom(ts.tv_nsec);
+
s = draw_stuff(width, height);
name = name_cairo_surface(fd, s);
@@ -178,8 +199,9 @@
cairo_image_surface_get_stride(s));
i = 0;
- while (ret = poll(p, 1, 20), ret >= 0) {
- if (ret == 0) {
+ while (ret = poll(p, 2, -1), ret >= 0) {
+ if (p[1].revents & POLLIN) {
+ read(p[1].fd, &expires, sizeof expires);
wl_surface_map(surface,
x + cos(i / 30.0) * 200,
y + sin(i / 31.0) * 200,