+static gboolean
+gtk_scrolled_window_calculate_velocity (GtkScrolledWindow *scrolled_window,
+ GdkEvent *event)
+{
+ GtkScrolledWindowPrivate *priv;
+ gdouble x_root, y_root;
+ guint32 _time;
+
+#define STILL_THRESHOLD 40
+
+ if (!gdk_event_get_root_coords (event, &x_root, &y_root))
+ return FALSE;
+
+ priv = scrolled_window->priv;
+ _time = gdk_event_get_time (event);
+
+ if (priv->last_motion_event_x_root != x_root ||
+ priv->last_motion_event_y_root != y_root ||
+ ABS (_time - priv->last_motion_event_time) > STILL_THRESHOLD)
+ {
+ priv->x_velocity = (priv->last_motion_event_x_root - x_root) /
+ (gdouble) (_time - priv->last_motion_event_time);
+ priv->y_velocity = (priv->last_motion_event_y_root - y_root) /
+ (gdouble) (_time - priv->last_motion_event_time);
+ }
+
+ priv->last_motion_event_x_root = x_root;
+ priv->last_motion_event_y_root = y_root;
+ priv->last_motion_event_time = _time;
+
+#undef STILL_THRESHOLD
+
+ return TRUE;
+}
+
+static gboolean
+gtk_scrolled_window_captured_button_release (GtkWidget *widget,
+ GdkEvent *event)
+{
+ GtkScrolledWindow *scrolled_window = GTK_SCROLLED_WINDOW (widget);
+ GtkScrolledWindowPrivate *priv = scrolled_window->priv;
+ GtkWidget *child;
+ gboolean overshoot;
+ guint button;
+ gdouble x_root, y_root;
+
+ if (gdk_event_get_button (event, &button) && button != 1)
+ return FALSE;
+
+ child = gtk_bin_get_child (GTK_BIN (widget));
+ if (!child)
+ return FALSE;
+
+ gtk_device_grab_remove (widget, priv->drag_device);
+ priv->drag_device = NULL;
+
+ if (priv->release_timeout_id)
+ {
+ g_source_remove (priv->release_timeout_id);
+ priv->release_timeout_id = 0;
+ }
+
+ overshoot = _gtk_scrolled_window_get_overshoot (scrolled_window, NULL, NULL);
+
+ if (priv->in_drag)
+ gdk_device_ungrab (gdk_event_get_device (event), gdk_event_get_time (event));
+ else
+ {
+ /* There hasn't been scrolling at all, so just let the
+ * child widget handle the button press normally
+ */
+ gtk_scrolled_window_release_captured_event (scrolled_window);
+
+ if (!overshoot)
+ return FALSE;
+ }
+ priv->in_drag = FALSE;
+
+ if (priv->button_press_event)
+ {
+ gdk_event_free (priv->button_press_event);
+ priv->button_press_event = NULL;
+ }
+
+ gtk_scrolled_window_calculate_velocity (scrolled_window, event);
+
+ /* Zero out vector components without a visible scrollbar */
+ if (!priv->hscrollbar_visible)
+ priv->x_velocity = 0;
+ if (!priv->vscrollbar_visible)
+ priv->y_velocity = 0;
+
+ if (priv->x_velocity != 0 || priv->y_velocity != 0 || overshoot)
+ {
+ gtk_scrolled_window_start_deceleration (scrolled_window);
+ priv->x_velocity = priv->y_velocity = 0;
+ priv->last_button_event_valid = FALSE;
+ }
+ else
+ {
+ gdk_event_get_root_coords (event, &x_root, &y_root);
+ priv->last_button_event_x_root = x_root;
+ priv->last_button_event_y_root = y_root;
+ priv->last_button_event_valid = TRUE;
+ }
+
+ if (priv->capture_button_press)
+ return TRUE;
+ else
+ return FALSE;
+}
+
+static gboolean
+gtk_scrolled_window_captured_motion_notify (GtkWidget *widget,
+ GdkEvent *event)
+{
+ GtkScrolledWindow *scrolled_window = GTK_SCROLLED_WINDOW (widget);
+ GtkScrolledWindowPrivate *priv = scrolled_window->priv;
+ gint old_overshoot_x, old_overshoot_y;
+ gint new_overshoot_x, new_overshoot_y;
+ GtkWidget *child;
+ GtkAdjustment *hadjustment;
+ GtkAdjustment *vadjustment;
+ gdouble dx, dy;
+ GdkModifierType state;
+ gdouble x_root, y_root;
+
+ gdk_event_get_state (event, &state);
+ if (!(state & GDK_BUTTON1_MASK))
+ return FALSE;
+
+ child = gtk_bin_get_child (GTK_BIN (widget));
+ if (!child)
+ return FALSE;
+
+ /* Check if we've passed the drag threshold */
+ gdk_event_get_root_coords (event, &x_root, &y_root);
+ if (!priv->in_drag)
+ {
+ if (gtk_drag_check_threshold (widget,
+ priv->last_button_event_x_root,
+ priv->last_button_event_y_root,
+ x_root, y_root))
+ {
+ if (priv->release_timeout_id)
+ {
+ g_source_remove (priv->release_timeout_id);
+ priv->release_timeout_id = 0;
+ }
+
+ priv->last_button_event_valid = FALSE;
+ priv->in_drag = TRUE;
+ }
+ else
+ return TRUE;
+ }
+
+ gdk_device_grab (priv->drag_device,
+ gtk_widget_get_window (widget),
+ GDK_OWNERSHIP_WINDOW,
+ TRUE,
+ GDK_BUTTON_RELEASE_MASK | GDK_BUTTON1_MOTION_MASK,
+ NULL,
+ gdk_event_get_time (event));
+
+ priv->last_button_event_valid = FALSE;
+
+ if (priv->button_press_event)
+ {
+ gdk_event_free (priv->button_press_event);
+ priv->button_press_event = NULL;
+ }
+
+ _gtk_scrolled_window_get_overshoot (scrolled_window,
+ &old_overshoot_x, &old_overshoot_y);
+
+ hadjustment = gtk_range_get_adjustment (GTK_RANGE (priv->hscrollbar));
+ if (hadjustment && priv->hscrollbar_visible)
+ {
+ dx = (priv->last_motion_event_x_root - x_root) + priv->unclamped_hadj_value;
+ _gtk_scrolled_window_set_adjustment_value (scrolled_window, hadjustment,
+ dx, TRUE, FALSE);
+ }
+
+ vadjustment = gtk_range_get_adjustment (GTK_RANGE (priv->vscrollbar));
+ if (vadjustment && priv->vscrollbar_visible)
+ {
+ dy = (priv->last_motion_event_y_root - y_root) + priv->unclamped_vadj_value;
+ _gtk_scrolled_window_set_adjustment_value (scrolled_window, vadjustment,
+ dy, TRUE, FALSE);
+ }
+
+ _gtk_scrolled_window_get_overshoot (scrolled_window,
+ &new_overshoot_x, &new_overshoot_y);
+
+ if (old_overshoot_x != new_overshoot_x ||
+ old_overshoot_y != new_overshoot_y)
+ {
+ if (new_overshoot_x >= 0 || new_overshoot_y >= 0)
+ {
+ /* We need to reallocate the widget to have it at
+ * negative offset, so there's a "gravity" on the
+ * bottom/right corner
+ */
+ gtk_widget_queue_resize (GTK_WIDGET (scrolled_window));
+ }
+ else if (new_overshoot_x < 0 || new_overshoot_y < 0)
+ _gtk_scrolled_window_allocate_overshoot_window (scrolled_window);
+ }
+
+ gtk_scrolled_window_calculate_velocity (scrolled_window, event);
+
+ return TRUE;
+}
+
+static gboolean
+gtk_scrolled_window_captured_button_press (GtkWidget *widget,
+ GdkEvent *event)
+{
+ GtkScrolledWindow *scrolled_window = GTK_SCROLLED_WINDOW (widget);
+ GtkScrolledWindowPrivate *priv = scrolled_window->priv;
+ GtkWidget *child;
+ GtkWidget *event_widget;
+ GdkDevice *source_device;
+ GdkInputSource source;
+ gdouble x_root, y_root;
+ guint button;
+
+ /* If scrollbars are not visible, we don't do kinetic scrolling */
+ if (!priv->vscrollbar_visible && !priv->hscrollbar_visible)
+ return FALSE;
+
+ source_device = gdk_event_get_source_device (event);
+ source = gdk_device_get_source (source_device);
+
+ if (source != GDK_SOURCE_TOUCHSCREEN)
+ return FALSE;
+
+ event_widget = gtk_get_event_widget (event);
+
+ /* If there's another scrolled window between the widget
+ * receiving the event and this capturing scrolled window,
+ * let it handle the events.
+ */
+ if (widget != gtk_widget_get_ancestor (event_widget, GTK_TYPE_SCROLLED_WINDOW))
+ return FALSE;
+
+ /* Check whether the button press is close to the previous one,
+ * take that as a shortcut to get the child widget handle events
+ */
+ gdk_event_get_root_coords (event, &x_root, &y_root);
+ if (priv->last_button_event_valid &&
+ ABS (x_root - priv->last_button_event_x_root) < TOUCH_BYPASS_CAPTURED_THRESHOLD &&
+ ABS (y_root - priv->last_button_event_y_root) < TOUCH_BYPASS_CAPTURED_THRESHOLD)
+ {
+ priv->last_button_event_valid = FALSE;
+ return FALSE;
+ }
+
+ priv->last_button_event_x_root = priv->last_motion_event_x_root = x_root;
+ priv->last_button_event_y_root = priv->last_motion_event_y_root = y_root;
+ priv->last_motion_event_time = gdk_event_get_time (event);
+ priv->last_button_event_valid = TRUE;
+
+ if (gdk_event_get_button (event, &button) && button != 1)
+ return FALSE;
+
+ child = gtk_bin_get_child (GTK_BIN (widget));
+ if (!child)
+ return FALSE;
+
+ if (priv->hscrollbar == event_widget || priv->vscrollbar == event_widget)
+ return FALSE;
+
+ priv->drag_device = gdk_event_get_device (event);
+ gtk_device_grab_add (widget, priv->drag_device, TRUE);
+
+ gtk_scrolled_window_cancel_deceleration (scrolled_window);
+
+ /* Only set the timeout if we're going to store an event */
+ if (priv->capture_button_press)
+ priv->release_timeout_id =
+ gdk_threads_add_timeout (RELEASE_EVENT_TIMEOUT,
+ (GSourceFunc) gtk_scrolled_window_release_captured_event,
+ scrolled_window);
+
+ priv->in_drag = FALSE;
+
+ if (priv->capture_button_press)
+ {
+ /* Store the button press event in
+ * case we need to propagate it later
+ */
+ priv->button_press_event = gdk_event_copy (event);
+ return TRUE;
+ }
+ else
+ return FALSE;
+}
+
+static gboolean
+gtk_scrolled_window_captured_event (GtkWidget *widget,
+ GdkEvent *event)
+{
+ gboolean retval = FALSE;
+ GtkScrolledWindowPrivate *priv = GTK_SCROLLED_WINDOW (widget)->priv;
+
+ if (gdk_window_get_window_type (event->any.window) == GDK_WINDOW_TEMP)
+ return FALSE;
+
+ switch (event->type)
+ {
+ case GDK_TOUCH_BEGIN:
+ case GDK_BUTTON_PRESS:
+ retval = gtk_scrolled_window_captured_button_press (widget, event);
+ break;
+ case GDK_TOUCH_END:
+ case GDK_BUTTON_RELEASE:
+ if (priv->drag_device)
+ retval = gtk_scrolled_window_captured_button_release (widget, event);
+ else
+ priv->last_button_event_valid = FALSE;
+ break;
+ case GDK_TOUCH_UPDATE:
+ case GDK_MOTION_NOTIFY:
+ if (priv->drag_device)
+ retval = gtk_scrolled_window_captured_motion_notify (widget, event);
+ break;
+ case GDK_LEAVE_NOTIFY:
+ case GDK_ENTER_NOTIFY:
+ if (priv->in_drag &&
+ event->crossing.mode != GDK_CROSSING_GRAB)
+ retval = TRUE;
+ break;
+ default:
+ break;
+ }
+
+ return retval;
+}
+