Merge lp:~vanvugt/gtk/fix-1698270 into lp:~ubuntu-desktop/gtk/ubuntugtk3

[Daniel van Vugt]

Fix irregular gdk_frame_clock_get_frame_time

This fixes stuttering in animations that rely on the regularity of
gdk_frame_clock_get_frame_time. (LP: #1698270)

BEFORE

gdkgears: 58 FPS and visibly stuttering

gnome-maps on a 59.95Hz monitor:
"paint" gdk_frame_clock_get_frame_time +17278μs
"paint" gdk_frame_clock_get_frame_time +17426μs
"paint" gdk_frame_clock_get_frame_time +17600μs
^^^ misses about 5% of frames, or stutters 3 times per sec ^^^

AFTER

gdkgears: 60 FPS and smoother

gnome-maps on a 59.95Hz monitor:
"paint" gdk_frame_clock_get_frame_time +16680μs
"paint" gdk_frame_clock_get_frame_time +16680μs
"paint" gdk_frame_clock_get_frame_time +16680μs
^^^ misses no frames ^^^

[lp:~vanvugt/gtk/fix-1698270]

579. By Daniel van Vugt on 2017-11-03

Merge latest 'ubuntugtk3' and fix changelog conflict.

580. By Daniel van Vugt on 2017-12-12

Merge latest 'ubuntugtk3' and fix changelog conflict.

[Daniel van Vugt (vanvugt)]

This patch has now landed upstream (on master GTK+4.0 only I think)
https://git.gnome.org/browse/gtk+/commit/?id=3b2f9395905ec2d9696bcf51497781236c95ec63

Unmerged revisions

580. By Daniel van Vugt on 2017-12-12

Merge latest 'ubuntugtk3' and fix changelog conflict.

579. By Daniel van Vugt on 2017-11-03

Merge latest 'ubuntugtk3' and fix changelog conflict.

578. By Daniel van Vugt on 2017-10-05

First import

=== modified file 'debian/changelog'
--- debian/changelog	2017-11-28 22:56:45 +0000
+++ debian/changelog	2017-12-12 07:56:30 +0000
@@ -1,3 +1,11 @@
+gtk+3.0 (3.22.26-2ubuntu2) UNRELEASED; urgency=medium
+
+  * Fix-irregular-gdk_frame_clock_get_frame_time-v3-ubuntu.patch:
+    This fixes stuttering in animations that rely on the regularity of
+    gdk_frame_clock_get_frame_time. (LP: #1698270)
+
+ -- Daniel van Vugt <[e-mail]>  Fri, 03 Nov 2017 15:41:31 +0800
+
 gtk+3.0 (3.22.26-2ubuntu1) bionic; urgency=medium
 
   * Merge with Debian. Remaining changes:

=== added file 'debian/patches/Fix-irregular-gdk_frame_clock_get_frame_time-v3-ubuntu.patch'
--- debian/patches/Fix-irregular-gdk_frame_clock_get_frame_time-v3-ubuntu.patch	1970-01-01 00:00:00 +0000
+++ debian/patches/Fix-irregular-gdk_frame_clock_get_frame_time-v3-ubuntu.patch	2017-12-12 07:56:30 +0000
@@ -0,0 +1,83 @@
+Description: Fix irregular gdk_frame_clock_get_frame_time
+ This fixes stuttering in animations that rely on the regularity of
+ gdk_frame_clock_get_frame_time.
+ .
+ BEFORE
+ gdkgears:
+ 58 FPS and visibly stuttering
+ gnome-maps on a 59.95Hz monitor:
+ "paint" g_get_monotonic_time +17278μs, gdk_frame_clock_get_frame_time +17278μs
+ "paint" g_get_monotonic_time +17449μs, gdk_frame_clock_get_frame_time +17426μs
+ "paint" g_get_monotonic_time +17620μs, gdk_frame_clock_get_frame_time +17600μs
+ .
+ AFTER
+ gdkgears:
+ 60 FPS and smoother
+ gnome-maps on a 59.95Hz monitor:
+ "paint" g_get_monotonic_time +18228μs, gdk_frame_clock_get_frame_time +16680μs
+ "paint" g_get_monotonic_time +15010μs, gdk_frame_clock_get_frame_time +16680μs
+ "paint" g_get_monotonic_time +17134μs, gdk_frame_clock_get_frame_time +16680μs
+Author: Daniel van Vugt <[e-mail]>
+Bug-Ubuntu: https://bugs.launchpad.net/bugs/1698270
+Bug: https://bugzilla.gnome.org/show_bug.cgi?id=787665
+Forwarded: yes
+Last-Update: 2017-09-15
+
+---
+ gdk/gdkframeclockidle.c | 31 ++++++++++++++++++++++++++++++-
+ 1 file changed, 30 insertions(+), 1 deletion(-)
+
+diff --git a/gdk/gdkframeclockidle.c b/gdk/gdkframeclockidle.c
+index 12897f4236..a0ca0ca1b9 100644
+--- a/gdk/gdkframeclockidle.c
++++ b/gdk/gdkframeclockidle.c
+@@ -123,6 +123,7 @@ gdk_frame_clock_idle_init (GdkFrameClockIdle *frame_clock_idle)
+   frame_clock_idle->priv = priv =
+     gdk_frame_clock_idle_get_instance_private (frame_clock_idle);
+ 
++  priv->frame_time = g_get_monotonic_time (); /* more sane than zero */
+   priv->freeze_count = 0;
+ }
+ 
+@@ -350,9 +351,37 @@ gdk_frame_clock_paint_idle (void *data)
+         case GDK_FRAME_CLOCK_PHASE_BEFORE_PAINT:
+           if (priv->freeze_count == 0)
+             {
+-              priv->frame_time = compute_frame_time (clock_idle);
++              gint64 frame_interval = FRAME_INTERVAL;
++              gint64 reset_frame_time;
++              gint64 smoothest_frame_time;
++              gint64 frame_time_error;
++              GdkFrameTimings *prev_timings =
++                gdk_frame_clock_get_current_timings (clock);
++
++              if (prev_timings && prev_timings->refresh_interval)
++                frame_interval = prev_timings->refresh_interval;
++
++              /* We are likely not getting precisely even callbacks in real
++               * time, particularly if the event loop is busy.
++               * This is a documented limitation in the precision of
++               * gdk_threads_add_timeout_full and g_timeout_add_full.
++               *
++               * In order to avoid this imprecision from compounding between
++               * frames and affecting visual smoothness, we correct frame_time
++               * to more precisely match the even refresh interval of the
++               * physical display. This also means we proactively avoid (most)
++               * missed frames before they occur.
++               */
++              smoothest_frame_time = priv->frame_time + frame_interval;
++              reset_frame_time = compute_frame_time (clock_idle);
++              frame_time_error = ABS (reset_frame_time - smoothest_frame_time);
++              if (frame_time_error >= frame_interval)
++                priv->frame_time = reset_frame_time;
++              else
++                priv->frame_time = smoothest_frame_time;
+ 
+               _gdk_frame_clock_begin_frame (clock);
++              /* Note "current" is different now so timings != prev_timings */
+               timings = gdk_frame_clock_get_current_timings (clock);
+ 
+               timings->frame_time = priv->frame_time;
+-- 
+2.14.1
+

=== modified file 'debian/patches/series'
--- debian/patches/series	2017-11-28 22:56:26 +0000
+++ debian/patches/series	2017-12-12 07:56:30 +0000
@@ -25,3 +25,4 @@
 unity-headerbar-maximized-mode.patch
 gtksocket-unscale-before-sending-configurenotify.patch
 no_content_hub.patch
+Fix-irregular-gdk_frame_clock_get_frame_time-v3-ubuntu.patch