[gtk/wip/exalm/swipe4] gestureswipe: Count last event when calculating velocity

[Alexander Mikhaylenko <alexm src gnome org>]

commit 700ca3b946717ddc31ae5211251cfa4069d60ef0
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Mon Oct 19 14:13:56 2020 +0500

    gestureswipe: Count last event when calculating velocity
    
    The last event, matching lifting the finger/releasing the mouse button,
    is important when there's a large delay between it and the previous events,
    as in when performing a movement, stopping, then releasing fingers as
    opposed to doing a swipe.
    
    If this event is skipped, doing this will result in kinetic deceleration
    matching the previous finger movement, while the expected behavior would
    be no deceleration.
    
    See also 5dc6194b98792d937c648835cfadbe64977db443 for a similar fix in
    GtkEventControllerScroll.

 gtk/gtkgestureswipe.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)
---
diff --git a/gtk/gtkgestureswipe.c b/gtk/gtkgestureswipe.c
index 59c7aba807..56de01c221 100644
--- a/gtk/gtkgestureswipe.c
+++ b/gtk/gtkgestureswipe.c
@@ -130,17 +130,16 @@ _gtk_gesture_swipe_clear_backlog (GtkGestureSwipe *gesture,
 }
 
 static void
-gtk_gesture_swipe_update (GtkGesture       *gesture,
-                          GdkEventSequence *sequence)
+gtk_gesture_swipe_append_event (GtkGestureSwipe  *swipe,
+                                GdkEventSequence *sequence)
 {
-  GtkGestureSwipe *swipe = GTK_GESTURE_SWIPE (gesture);
   GtkGestureSwipePrivate *priv;
   EventData new;
   double x, y;
 
   priv = gtk_gesture_swipe_get_instance_private (swipe);
-  _gtk_gesture_get_last_update_time (gesture, sequence, &new.evtime);
-  gtk_gesture_get_point (gesture, sequence, &x, &y);
+  _gtk_gesture_get_last_update_time (GTK_GESTURE (swipe), sequence, &new.evtime);
+  gtk_gesture_get_point (GTK_GESTURE (swipe), sequence, &x, &y);
 
   new.x = x;
   new.y = y;
@@ -149,6 +148,15 @@ gtk_gesture_swipe_update (GtkGesture       *gesture,
   g_array_append_val (priv->events, new);
 }
 
+static void
+gtk_gesture_swipe_update (GtkGesture       *gesture,
+                          GdkEventSequence *sequence)
+{
+  GtkGestureSwipe *swipe = GTK_GESTURE_SWIPE (gesture);
+
+  gtk_gesture_swipe_append_event (swipe, sequence);
+}
+
 static void
 _gtk_gesture_swipe_calculate_velocity (GtkGestureSwipe *gesture,
                                        double          *velocity_x,
@@ -202,6 +210,8 @@ gtk_gesture_swipe_end (GtkGesture       *gesture,
   if (gtk_gesture_is_active (gesture))
     return;
 
+  gtk_gesture_swipe_append_event (swipe, sequence);
+
   priv = gtk_gesture_swipe_get_instance_private (swipe);
   _gtk_gesture_swipe_calculate_velocity (swipe, &velocity_x, &velocity_y);
   g_signal_emit (gesture, signals[SWIPE], 0, velocity_x, velocity_y);