gtk2/gdk/gdkframeclockprivate.h
Alexander Larsson 9ef3e70040 frame-clock: New approach in smoothing frame clock
In commit c6901a8b, the frame clock reported time was changed from
simply reporting the time we ran the frame clock cycle to reporting a
smoothed value that increased by the frame interval each time it was
called.

However, this change caused some problems, such as:
 https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/1415
 https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/1416
 https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/1482

I think a lot of this is caused by the fact that we just overwrote the
old frame time with the smoothed, monotonous timestamp, breaking
some things that relied on knowing the actual time something happened.

This is a new approach to doing the smoothing that is more explicit.
The "frame_time" we store is the actual time we ran the update cycle,
and then we separately compute and store the derived smoothed time and
its period, allowing us to easily return a smoothed time at any time
by rounding the time difference to an integer number of frames.

The initial frame_time can be somewhat arbitrary, as it depends on the
first cycle which is not driven by the frame clock. But follow-up
cycles are typically tied to the the compositor sending the drawn
signal. It may happen that the initial frame is exactly in the middle
between two frames where jitter causes us to randomly round in
different directions when rounding to nearest frame. To fix this we
additionally do a quadratic convergence towards the "real" time,
during presentation driven clock cycles (i.e. when the frame times are
small).
2020-05-28 15:13:07 +02:00

133 lines
4.3 KiB
C

/* GDK - The GIMP Drawing Kit
* Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
/*
* Modified by the GTK+ Team and others 1997-2010. See the AUTHORS
* file for a list of people on the GTK+ Team. See the ChangeLog
* files for a list of changes. These files are distributed with
* GTK+ at ftp://ftp.gtk.org/pub/gtk/.
*/
/* Uninstalled header, internal to GDK */
#ifndef __GDK_FRAME_CLOCK_PRIVATE_H__
#define __GDK_FRAME_CLOCK_PRIVATE_H__
#include <gdk/gdkframeclock.h>
#include <gdk/gdkprofilerprivate.h>
G_BEGIN_DECLS
/**
* GdkFrameClock:
* @parent_instance: The parent instance.
*/
struct _GdkFrameClock
{
GObject parent_instance;
/*< private >*/
GdkFrameClockPrivate *priv;
};
/**
* GdkFrameClockClass:
* @parent_class: The parent class.
* @get_frame_time: Gets the time that should currently be used for
* animations.
* @request_phase: Asks the frame clock to run a particular phase.
* @begin_updating: Starts updates for an animation.
* @end_updating: Stops updates for an animation.
* @freeze:
* @thaw:
*/
struct _GdkFrameClockClass
{
GObjectClass parent_class;
/*< public >*/
gint64 (* get_frame_time) (GdkFrameClock *clock);
void (* request_phase) (GdkFrameClock *clock,
GdkFrameClockPhase phase);
void (* begin_updating) (GdkFrameClock *clock);
void (* end_updating) (GdkFrameClock *clock);
void (* freeze) (GdkFrameClock *clock);
void (* thaw) (GdkFrameClock *clock);
/* signals */
/* void (* flush_events) (GdkFrameClock *clock); */
/* void (* before_paint) (GdkFrameClock *clock); */
/* void (* update) (GdkFrameClock *clock); */
/* void (* layout) (GdkFrameClock *clock); */
/* void (* paint) (GdkFrameClock *clock); */
/* void (* after_paint) (GdkFrameClock *clock); */
/* void (* resume_events) (GdkFrameClock *clock); */
};
struct _GdkFrameTimings
{
/*< private >*/
guint ref_count;
gint64 frame_counter;
guint64 cookie;
gint64 frame_time;
gint64 smoothed_frame_time;
gint64 drawn_time;
gint64 presentation_time;
gint64 refresh_interval;
gint64 predicted_presentation_time;
#ifdef G_ENABLE_DEBUG
gint64 layout_start_time;
gint64 paint_start_time;
gint64 frame_end_time;
#endif /* G_ENABLE_DEBUG */
guint complete : 1;
guint slept_before : 1;
};
void _gdk_frame_clock_inhibit_freeze (GdkFrameClock *clock);
void _gdk_frame_clock_uninhibit_freeze (GdkFrameClock *clock);
void _gdk_frame_clock_begin_frame (GdkFrameClock *clock);
void _gdk_frame_clock_debug_print_timings (GdkFrameClock *clock,
GdkFrameTimings *timings);
void _gdk_frame_clock_add_timings_to_profiler (GdkFrameClock *frame_clock,
GdkFrameTimings *timings);
GdkFrameTimings *_gdk_frame_timings_new (gint64 frame_counter);
gboolean _gdk_frame_timings_steal (GdkFrameTimings *timings,
gint64 frame_counter);
void _gdk_frame_clock_emit_flush_events (GdkFrameClock *frame_clock);
void _gdk_frame_clock_emit_before_paint (GdkFrameClock *frame_clock);
void _gdk_frame_clock_emit_update (GdkFrameClock *frame_clock);
void _gdk_frame_clock_emit_layout (GdkFrameClock *frame_clock);
void _gdk_frame_clock_emit_paint (GdkFrameClock *frame_clock);
void _gdk_frame_clock_emit_after_paint (GdkFrameClock *frame_clock);
void _gdk_frame_clock_emit_resume_events (GdkFrameClock *frame_clock);
G_END_DECLS
#endif /* __GDK_FRAME_CLOCK_PRIVATE_H__ */