From 6f094bd399f4197e7036d8306337b4b0ee72ca65 Mon Sep 17 00:00:00 2001 From: Daniel van Vugt Date: Tue, 13 Aug 2019 18:03:26 +0800 Subject: [PATCH] clutter/master-clock-default: Sync timelines to hardware vsync Previously clutter timelines advanced according to `g_source_get_time`. But that meant the spatial stepping of animations was visibly sensitive to any irregularities in the main loop. It also represented a time older [1] than the intended presentation time of each frame. Now we instead use `master_clock_get_next_presentation_time`. This ensures we get the smoothness of hardware vsync as well as being closer to the actual presentation time. This means, for example, backends like Xorg that move the hardware cursor independently of repaints will have their animations more closely matching the hardware cursor position. So the cursor appears to stick more closely when dragging windows or on the lock screen etc. [1] "older" = (refresh_interval - sync_delay) = ~14ms for 60Hz Closes: https://gitlab.gnome.org/GNOME/mutter/issues/25 https://gitlab.gnome.org/GNOME/mutter/merge_requests/724 --- .../clutter/clutter-master-clock-default.c | 26 ++++++++++++++++++- 1 file changed, 25 insertions(+), 1 deletion(-) diff --git a/clutter/clutter/clutter-master-clock-default.c b/clutter/clutter/clutter-master-clock-default.c index 8d50ab8f3..ac55f1b42 100644 --- a/clutter/clutter/clutter-master-clock-default.c +++ b/clutter/clutter/clutter-master-clock-default.c @@ -190,6 +190,26 @@ master_clock_get_swap_wait_time (ClutterMasterClockDefault *master_clock) } } +static int64_t +master_clock_get_next_presentation_time (ClutterMasterClockDefault *master_clock) +{ + ClutterStageManager *stage_manager = clutter_stage_manager_get_default (); + const GSList *stages, *l; + int64_t earliest = -1; + + stages = clutter_stage_manager_peek_stages (stage_manager); + + for (l = stages; l != NULL; l = l->next) + { + gint64 t = _clutter_stage_get_next_presentation_time (l->data); + + if (earliest == -1 || (t != -1 && t < earliest)) + earliest = t; + } + + return earliest; +} + static void master_clock_schedule_stage_updates (ClutterMasterClockDefault *master_clock) { @@ -466,7 +486,11 @@ clutter_clock_dispatch (GSource *source, COGL_TRACE_BEGIN (ClutterMasterClockTick, "Master Clock (tick)"); /* Get the time to use for this frame */ - master_clock->cur_tick = g_source_get_time (source); + master_clock->cur_tick = master_clock_get_next_presentation_time (master_clock); + + /* On the first frame the backend might not have an answer */ + if (master_clock->cur_tick <= 0) + master_clock->cur_tick = g_source_get_time (source); #ifdef CLUTTER_ENABLE_DEBUG master_clock->remaining_budget = master_clock->frame_budget;