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evdev: add callback to constrain the pointer position

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Add a new callback that is called prior to emitting pointer
motion events and that can modify the new pointer position.
The main purpose is allowing multiscreen apps to prevent the
pointer for entering the dead area that exists when the screens
are not the same size, but it could also used to implement
pointer barriers.
A callback is needed to make sure that the hook is called early
enough and the Clutter state is always consistent.

https://bugzilla.gnome.org/show_bug.cgi?id=706652
This commit is contained in:
Giovanni Campagna
2013-08-23 12:15:40 +02:00
parent 89d09a07d3
commit aef3d0022c
2 changed files with 78 additions and 2 deletions
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53
clutter/evdev/clutter-device-manager-evdev.c
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@ -73,6 +73,10 @@ struct _ClutterDeviceManagerEvdevPrivate
ClutterInputDevice *core_pointer;
ClutterInputDevice *core_keyboard;
ClutterPointerConstrainCallback constrain_callback;
gpointer constrain_data;
GDestroyNotify constrain_data_notify;
ClutterStageManager *stage_manager;
guint stage_added_handler;
guint stage_removed_handler;
@ -259,8 +263,17 @@ notify_relative_motion (ClutterEventSource *source,
clutter_input_device_get_coords (manager_evdev->priv->core_pointer, NULL, &point);
new_x = point.x + dx;
new_y = point.y + dy;
new_x = CLAMP (new_x, 0.f, stage_width - 1);
new_y = CLAMP (new_y, 0.f, stage_height - 1);
if (manager_evdev->priv->constrain_callback)
{
manager_evdev->priv->constrain_callback (manager_evdev->priv->core_pointer, time_, &new_x, &new_y,
manager_evdev->priv->constrain_data);
}
else
{
new_x = CLAMP (new_x, 0.f, stage_width - 1);
new_y = CLAMP (new_y, 0.f, stage_height - 1);
}
event->motion.time = time_;
event->motion.stage = stage;
@ -1029,6 +1042,9 @@ clutter_device_manager_evdev_finalize (GObject *object)
}
g_slist_free (priv->event_sources);
if (priv->constrain_data_notify)
priv->constrain_data_notify (priv->constrain_data);
G_OBJECT_CLASS (clutter_device_manager_evdev_parent_class)->finalize (object);
}
@ -1313,3 +1329,36 @@ clutter_evdev_set_keyboard_map (ClutterDeviceManager *evdev,
for (i = 0; i < priv->keys->len; i++)
xkb_state_update_key (priv->xkb, g_array_index (priv->keys, guint32, i), XKB_KEY_DOWN);
}
/**
* clutter_evdev_set_pointer_constrain_callback:
* @evdev: the #ClutterDeviceManager created by the evdev backend
* @callback: the callback
* @user_data:
* @user_data_notify:
*
* Sets a callback to be invoked for every pointer motion. The callback
* can then modify the new pointer coordinates to constrain movement within
* a specific region.
*/
void
clutter_evdev_set_pointer_constrain_callback (ClutterDeviceManager *evdev,
ClutterPointerConstrainCallback callback,
gpointer user_data,
GDestroyNotify user_data_notify)
{
ClutterDeviceManagerEvdev *manager_evdev;
ClutterDeviceManagerEvdevPrivate *priv;
g_return_if_fail (CLUTTER_IS_DEVICE_MANAGER_EVDEV (evdev));
manager_evdev = CLUTTER_DEVICE_MANAGER_EVDEV (evdev);
priv = manager_evdev->priv;
if (priv->constrain_data_notify)
priv->constrain_data_notify (priv->constrain_data);
priv->constrain_callback = callback;
priv->constrain_data = user_data;
priv->constrain_data_notify = user_data_notify;
}