IO_METHOD(IoClutter, getDefaultFrameRate) {
return IONUMBER(clutter_get_default_frame_rate());
}
/*
* master_clock_next_frame_delay:
* @master_clock: a #ClutterMasterClock
*
* Computes the number of delay before we need to draw the next frame.
*
* Return value: -1 if there is no next frame pending, otherwise the
* number of millseconds before the we need to draw the next frame
*/
static gint
master_clock_next_frame_delay (ClutterMasterClock *master_clock)
{
gint64 now, next;
if (!master_clock_is_running (master_clock))
return -1;
/* When we have sync-to-vblank, we count on swap-buffer requests (or
* swap-buffer-complete events if supported in the backend) to throttle our
* frame rate so no additional delay is needed to start the next frame.
*
* If the master-clock has become idle due to no timeline progression causing
* redraws then we can no longer rely on vblank synchronization because the
* last real stage update/redraw may have happened a long time ago and so we
* fallback to polling for timeline progressions every 1/frame_rate seconds.
*
* (NB: if there aren't even any timelines running then the master clock will
* be completely stopped in master_clock_is_running())
*/
if (clutter_feature_available (CLUTTER_FEATURE_SYNC_TO_VBLANK) &&
!master_clock->idle)
{
CLUTTER_NOTE (SCHEDULER, "vblank available and updated stages");
return 0;
}
if (master_clock->prev_tick == 0)
{
/* If we weren't previously running, then draw the next frame
* immediately
*/
CLUTTER_NOTE (SCHEDULER, "draw the first frame immediately");
return 0;
}
/* Otherwise, wait at least 1/frame_rate seconds since we last
* started a frame
*/
#if GLIB_CHECK_VERSION (2, 27, 3)
now = g_source_get_time (master_clock->source);
#else
{
GTimeVal source_time;
g_source_get_current_time (master_clock->source, &source_time);
now = source_time.tv_sec * 1000000L + source_time.tv_usec;
}
#endif
next = master_clock->prev_tick;
/* If time has gone backwards then there's no way of knowing how
long we should wait so let's just dispatch immediately */
if (now <= next)
{
CLUTTER_NOTE (SCHEDULER, "Time has gone backwards");
return 0;
}
next += (1000000L / clutter_get_default_frame_rate ());
if (next <= now)
{
CLUTTER_NOTE (SCHEDULER, "Less than %lu microsecs",
1000000L / (gulong) clutter_get_default_frame_rate ());
return 0;
}
else
{
CLUTTER_NOTE (SCHEDULER, "Waiting %" G_GINT64_FORMAT " msecs",
(next - now) / 1000);
return (next - now) / 1000;
}
}