[gtk: 1/4] frame clock: Track if paint is caused by thaw or not

[Matthias Clasen <matthiasc src gnome org>]

commit 82c314f1af3fca776d4e7796ab7555b7182c8464
Author: Alexander Larsson <alexl redhat com>
Date:   Fri Jun 5 11:16:57 2020 +0200

    frame clock: Track if paint is caused by thaw or not
    
    When we get to a paint cycle we now know if this was caused by a
    thaw, which typically means last frame was drawn, or some other event.
    
    In the first case the time of the cycle is tied to the vblank in some
    sense, and in the others it is essentially random. We can use this
    information to compute better frame times. (Will be done in later
    commits.)

 gdk/gdkframeclockidle.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)
---
diff --git a/gdk/gdkframeclockidle.c b/gdk/gdkframeclockidle.c
index ef32ad518a..cf43f7442f 100644
--- a/gdk/gdkframeclockidle.c
+++ b/gdk/gdkframeclockidle.c
@@ -56,6 +56,7 @@ struct _GdkFrameClockIdlePrivate
   GdkFrameClockPhase phase;
 
   guint in_paint_idle : 1;
+  guint paint_is_thaw : 1;
 #ifdef G_OS_WIN32
   guint begin_period : 1;
 #endif
@@ -275,7 +276,8 @@ gdk_frame_clock_idle_get_frame_time (GdkFrameClock *clock)
     (priv)->updating_count > 0))
 
 static void
-maybe_start_idle (GdkFrameClockIdle *clock_idle)
+maybe_start_idle (GdkFrameClockIdle *clock_idle,
+                  gboolean caused_by_thaw)
 {
   GdkFrameClockIdlePrivate *priv = clock_idle->priv;
 
@@ -303,6 +305,7 @@ maybe_start_idle (GdkFrameClockIdle *clock_idle)
       if (!priv->in_paint_idle &&
          priv->paint_idle_id == 0 && RUN_PAINT_IDLE (priv))
         {
+          priv->paint_is_thaw = caused_by_thaw;
           priv->paint_idle_id = g_timeout_add_full (GDK_PRIORITY_REDRAW,
                                                     min_interval,
                                                     gdk_frame_clock_paint_idle,
@@ -560,7 +563,7 @@ gdk_frame_clock_paint_idle (void *data)
     {
       priv->min_next_frame_time = compute_min_next_frame_time (clock_idle,
                                                                priv->frame_time);
-      maybe_start_idle (clock_idle);
+      maybe_start_idle (clock_idle, FALSE);
     }
 
   if (priv->freeze_count == 0)
@@ -580,7 +583,7 @@ gdk_frame_clock_idle_request_phase (GdkFrameClock      *clock,
   GdkFrameClockIdlePrivate *priv = clock_idle->priv;
 
   priv->requested |= phase;
-  maybe_start_idle (clock_idle);
+  maybe_start_idle (clock_idle, FALSE);
 }
 
 static void
@@ -599,7 +602,7 @@ gdk_frame_clock_idle_begin_updating (GdkFrameClock *clock)
 #endif
 
   priv->updating_count++;
-  maybe_start_idle (clock_idle);
+  maybe_start_idle (clock_idle, FALSE);
 }
 
 static void
@@ -649,7 +652,7 @@ gdk_frame_clock_idle_thaw (GdkFrameClock *clock)
   priv->freeze_count--;
   if (priv->freeze_count == 0)
     {
-      maybe_start_idle (clock_idle);
+      maybe_start_idle (clock_idle, TRUE);
       /* If nothing is requested so we didn't start an idle, we need
        * to skip to the end of the state chain, since the idle won't
        * run and do it for us.