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gtk,scrolledwindow: Improve initial velocity calculation

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Velocity calculation has been refactored out of the captured motion events
handler, and also has more tolerance defore determining that a drag is actually
still.
This commit is contained in:
Carlos Garnacho
2011-12-23 17:10:56 +01:00
parent 0e05d33eee
commit 18e451da6e
1 changed files with 38 additions and 12 deletions
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50
gtk/gtkscrolledwindow.c
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@@ -2409,6 +2409,41 @@ gtk_scrolled_window_release_captured_events (GtkScrolledWindow *scrolled_window)
return FALSE;
}
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)
@@ -2453,6 +2488,8 @@ gtk_scrolled_window_captured_button_release (GtkWidget *widget,
}
priv->in_drag = FALSE;
gtk_scrolled_window_calculate_velocity (scrolled_window, _event);
/* Zero out vector components without a visible scrollbar */
if (!priv->hscrollbar_visible)
priv->x_velocity = 0;
@@ -2574,18 +2611,7 @@ gtk_scrolled_window_captured_motion_notify (GtkWidget *widget,
_gtk_scrolled_window_allocate_overshoot_window (scrolled_window);
}
/* Find out X/Y components of the velocity vector, in pixels/ms */
if (event->time != priv->last_motion_event_time)
{
priv->x_velocity = (priv->last_motion_event_x_root - event->x_root) /
(gdouble) (event->time - priv->last_motion_event_time);
priv->y_velocity = (priv->last_motion_event_y_root - event->y_root) /
(gdouble) (event->time - priv->last_motion_event_time);
priv->last_motion_event_x_root = event->x_root;
priv->last_motion_event_y_root = event->y_root;
priv->last_motion_event_time = event->time;
}
gtk_scrolled_window_calculate_velocity (scrolled_window, _event);
return GTK_CAPTURED_EVENT_HANDLED;
}