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scrolledwindow: Trigger builtin kinetic deceleration on libinput devices
The libinput driver will send a 0/0 scroll event on touchpads and other devices where it knows scrolling stopped for sure. Use these events to trigger kinetic scrolling from there. The mechanism is similar to GtkGestureSwipe, we keep a backlog of the latest dx/dy till a previous point in time, and calculate the final velocities from there, with the difference we're dealing with scroll units, and not pixel distances. https://bugzilla.gnome.org/show_bug.cgi?id=749770
This commit is contained in:
Carlos Garnacho
parent
fc28303948
commit
48bfabe59e
@ -149,6 +149,7 @@
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#define MAX_OVERSHOOT_DISTANCE 100
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#define DECELERATION_FRICTION 4
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#define OVERSHOOT_FRICTION 20
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#define SCROLL_CAPTURE_THRESHOLD_MS 150
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/* Animated scrolling */
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#define ANIMATION_DURATION 200
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@ -180,6 +181,13 @@ typedef struct
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guint over_timeout_id;
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} Indicator;
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typedef struct
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{
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gdouble dx;
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gdouble dy;
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guint32 evtime;
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} ScrollHistoryElem;
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struct _GtkScrolledWindowPrivate
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{
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GtkWidget *hscrollbar;
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@ -208,6 +216,9 @@ struct _GtkScrolledWindowPrivate
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GtkGesture *long_press_gesture;
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GtkGesture *swipe_gesture;
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GArray *scroll_history;
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GdkDevice *scroll_device;
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/* These two gestures are mutually exclusive */
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GtkGesture *drag_gesture;
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GtkGesture *pan_gesture;
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@ -869,7 +880,7 @@ scrolled_window_drag_end_cb (GtkScrolledWindow *scrolled_window,
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}
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static void
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scrolled_window_swipe_cb (GtkScrolledWindow *scrolled_window,
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gtk_scrolled_window_decelerate (GtkScrolledWindow *scrolled_window,
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gdouble x_velocity,
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gdouble y_velocity)
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{
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@ -877,8 +888,8 @@ scrolled_window_swipe_cb (GtkScrolledWindow *scrolled_window,
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gboolean overshoot;
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overshoot = _gtk_scrolled_window_get_overshoot (scrolled_window, NULL, NULL);
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priv->x_velocity = -x_velocity;
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priv->y_velocity = -y_velocity;
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priv->x_velocity = x_velocity;
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priv->y_velocity = y_velocity;
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/* Zero out vector components for which we don't scroll */
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if (!may_hscroll (scrolled_window))
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@ -893,6 +904,14 @@ scrolled_window_swipe_cb (GtkScrolledWindow *scrolled_window,
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}
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}
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static void
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scrolled_window_swipe_cb (GtkScrolledWindow *scrolled_window,
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gdouble x_velocity,
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gdouble y_velocity)
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{
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gtk_scrolled_window_decelerate (scrolled_window, -x_velocity, -y_velocity);
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}
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static void
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scrolled_window_long_press_cb (GtkScrolledWindow *scrolled_window,
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gdouble x,
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@ -1114,6 +1133,87 @@ get_scroll_unit (GtkScrolledWindow *sw,
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return scroll_unit;
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}
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static void
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scroll_history_push (GtkScrolledWindow *sw,
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GdkEventScroll *event)
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{
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GtkScrolledWindowPrivate *priv = sw->priv;
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ScrollHistoryElem new_item;
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guint i;
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if (event->direction != GDK_SCROLL_SMOOTH)
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return;
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for (i = 0; i < priv->scroll_history->len; i++)
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{
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ScrollHistoryElem *elem;
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elem = &g_array_index (priv->scroll_history, ScrollHistoryElem, i);
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if (elem->evtime >= event->time - SCROLL_CAPTURE_THRESHOLD_MS)
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break;
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}
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if (i > 0)
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g_array_remove_range (priv->scroll_history, 0, i);
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new_item.dx = event->delta_x;
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new_item.dy = event->delta_y;
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new_item.evtime = event->time;
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g_array_append_val (priv->scroll_history, new_item);
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}
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static void
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scroll_history_reset (GtkScrolledWindow *sw)
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{
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GtkScrolledWindowPrivate *priv = sw->priv;
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if (priv->scroll_history->len == 0)
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return;
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g_array_remove_range (priv->scroll_history, 0,
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priv->scroll_history->len);
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}
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static gboolean
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scroll_history_finish (GtkScrolledWindow *sw,
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gdouble *velocity_x,
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gdouble *velocity_y)
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{
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GtkScrolledWindowPrivate *priv = sw->priv;
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gdouble accum_dx = 0, accum_dy = 0;
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guint32 first = 0, last = 0;
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gdouble xunit, yunit;
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guint i;
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if (priv->scroll_history->len == 0)
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return FALSE;
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for (i = 0; i < priv->scroll_history->len; i++)
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{
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ScrollHistoryElem *elem;
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elem = &g_array_index (priv->scroll_history, ScrollHistoryElem, i);
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accum_dx += elem->dx;
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accum_dy += elem->dy;
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last = elem->evtime;
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if (i == 0)
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first = elem->evtime;
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}
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if (last == first)
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return FALSE;
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xunit = get_scroll_unit (sw, GTK_ORIENTATION_HORIZONTAL);
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yunit = get_scroll_unit (sw, GTK_ORIENTATION_VERTICAL);
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*velocity_x = (accum_dx * 1000 * xunit) / (last - first);
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*velocity_y = (accum_dy * 1000 * yunit) / (last - first);
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scroll_history_reset (sw);
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return TRUE;
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}
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static gboolean
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captured_event_cb (GtkWidget *widget,
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GdkEvent *event)
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@ -1127,20 +1227,31 @@ captured_event_cb (GtkWidget *widget,
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sw = GTK_SCROLLED_WINDOW (widget);
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priv = sw->priv;
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source_device = gdk_event_get_source_device (event);
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if (event->type == GDK_SCROLL)
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{
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gdouble dx, dy;
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gdouble dx, dy, vel_x, vel_y;
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/* The libinput driver may generate a final event with dx=dy=0
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* after scrolling finished, this is usually an indication that
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* the deceleration animation just started, so we definitely
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* shouldn't cancel it.
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* after scrolling finished, start kinetic scrolling when this
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* happens.
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*/
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if (event->scroll.direction != GDK_SCROLL_SMOOTH ||
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(gdk_event_get_scroll_deltas (event, &dx, &dy) &&
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(dx != 0 || dy != 0)))
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gtk_scrolled_window_cancel_deceleration (sw);
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gdk_event_get_scroll_deltas (event, &dx, &dy);
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if (priv->scroll_device != source_device)
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{
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priv->scroll_device = source_device;
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scroll_history_reset (sw);
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}
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scroll_history_push (sw, &event->scroll);
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if (event->scroll.direction == GDK_SCROLL_SMOOTH &&
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dx == 0 && dy == 0 &&
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scroll_history_finish (sw, &vel_x, &vel_y))
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gtk_scrolled_window_decelerate (sw, vel_x, vel_y);
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return GDK_EVENT_PROPAGATE;
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}
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@ -1152,7 +1263,6 @@ captured_event_cb (GtkWidget *widget,
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event->type != GDK_LEAVE_NOTIFY)
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return GDK_EVENT_PROPAGATE;
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source_device = gdk_event_get_source_device (event);
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input_source = gdk_device_get_source (source_device);
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if (input_source == GDK_SOURCE_KEYBOARD ||
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@ -1265,6 +1375,8 @@ gtk_scrolled_window_init (GtkScrolledWindow *scrolled_window)
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G_CALLBACK (scrolled_window_long_press_cancelled_cb),
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scrolled_window);
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priv->scroll_history = g_array_new (FALSE, FALSE, sizeof (ScrollHistoryElem));
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gtk_scrolled_window_set_kinetic_scrolling (scrolled_window, TRUE);
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gtk_scrolled_window_set_capture_button_press (scrolled_window, TRUE);
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@ -1877,6 +1989,7 @@ gtk_scrolled_window_destroy (GtkWidget *widget)
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g_clear_object (&priv->drag_gesture);
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g_clear_object (&priv->swipe_gesture);
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g_clear_object (&priv->long_press_gesture);
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g_clear_pointer (&priv->scroll_history, (GDestroyNotify) g_array_unref);
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GTK_WIDGET_CLASS (gtk_scrolled_window_parent_class)->destroy (widget);
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}
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@ -2966,7 +3079,10 @@ start_scroll_deceleration_cb (gpointer user_data)
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GtkScrolledWindowPrivate *priv = scrolled_window->priv;
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priv->scroll_events_overshoot_id = 0;
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if (!priv->deceleration_id)
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gtk_scrolled_window_start_deceleration (scrolled_window);
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return FALSE;
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}
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