update_from_event

Forcibly updates the state of the this using a Event

This function should never be used by applications: it is meant for integration with embedding toolkits, like clutter-gtk

Embedding toolkits that disable the event collection inside Clutter need to use this function to update the state of input devices depending on a Event that they are going to submit to the event handling code in Clutter though do_event. Since the input devices hold the state that is going to be used to fill in fields like the ButtonEvent click count, or to emit synthesized events like clutter_enter and clutter_leave, it is necessary for embedding toolkits to also be responsible of updating the input device state.

For instance, this might be the code to translate an embedding toolkit native motion notification into a Clutter MotionEvent and ask Clutter to process it:

  ClutterEvent c_event;

  translate_native_event_to_clutter (native_event, &c_event);

  clutter_do_event (&c_event);

Before letting do_event process the event, it is necessary to call update_from_event:

  ClutterEvent c_event;
  ClutterDeviceManager *manager;
  ClutterInputDevice *device;

  translate_native_event_to_clutter (native_event, &c_event);

  // get the device manager
  manager = clutter_device_manager_get_default ();

  // use the default Core Pointer that Clutter backends register by default
  device = clutter_device_manager_get_core_device (manager, %CLUTTER_POINTER_DEVICE);

  // update the state of the input device
  clutter_input_device_update_from_event (device, &c_event, FALSE);

  clutter_do_event (&c_event);

The update_stage boolean argument should be used when the input device enters and leaves a Stage; it will use the Stage field of the passed event to update the stage associated to the input device.

Parameters:

this	a InputDevice
event	a Event
update_stage	whether to update the Stage of the this using the stage of the event