Description [src]

abstract class Gtk.Gesture : Gtk.EventController
  /* No available fields */

GtkGesture is the base class for gesture recognition.

Although GtkGesture is quite generalized to serve as a base for multi-touch gestures, it is suitable to implement single-touch and pointer-based gestures (using the special NULL GdkEventSequence value for these).

The number of touches that a GtkGesture need to be recognized is controlled by the GtkGesture:n-points property, if a gesture is keeping track of less or more than that number of sequences, it won’t check whether the gesture is recognized.

As soon as the gesture has the expected number of touches, it will check regularly if it is recognized, the criteria to consider a gesture as “recognized” is left to GtkGesture subclasses.

A recognized gesture will then emit the following signals:

Event propagation

In order to receive events, a gesture needs to set a propagation phase through gtk_event_controller_set_propagation_phase().

In the capture phase, events are propagated from the toplevel down to the target widget, and gestures that are attached to containers above the widget get a chance to interact with the event before it reaches the target.

In the bubble phase, events are propagated up from the target widget to the toplevel, and gestures that are attached to containers above the widget get a chance to interact with events that have not been handled yet.

States of a sequence

Whenever input interaction happens, a single event may trigger a cascade of GtkGestures, both across the parents of the widget receiving the event and in parallel within an individual widget. It is a responsibility of the widgets using those gestures to set the state of touch sequences accordingly in order to enable cooperation of gestures around the GdkEventSequences triggering those.

Within a widget, gestures can be grouped through gtk_gesture_group(). Grouped gestures synchronize the state of sequences, so calling gtk_gesture_set_state() on one will effectively propagate the state throughout the group.

By default, all sequences start out in the GTK_EVENT_SEQUENCE_NONE state, sequences in this state trigger the gesture event handler, but event propagation will continue unstopped by gestures.

If a sequence enters into the GTK_EVENT_SEQUENCE_DENIED state, the gesture group will effectively ignore the sequence, letting events go unstopped through the gesture, but the “slot” will still remain occupied while the touch is active.

If a sequence enters in the GTK_EVENT_SEQUENCE_CLAIMED state, the gesture group will grab all interaction on the sequence, by:

  • Setting the same sequence to GTK_EVENT_SEQUENCE_DENIED on every other gesture group within the widget, and every gesture on parent widgets in the propagation chain.
  • Emitting GtkGesture::cancel on every gesture in widgets underneath in the propagation chain.
  • Stopping event propagation after the gesture group handles the event.

Note: if a sequence is set early to GTK_EVENT_SEQUENCE_CLAIMED on GDK_TOUCH_BEGIN/GDK_BUTTON_PRESS (so those events are captured before reaching the event widget, this implies GTK_PHASE_CAPTURE), one similar event will be emulated if the sequence changes to GTK_EVENT_SEQUENCE_DENIED. This way event coherence is preserved before event propagation is unstopped again.

Sequence states can’t be changed freely. See gtk_gesture_set_state() to know about the possible lifetimes of a GdkEventSequence.

Touchpad gestures

On the platforms that support it, GtkGesture will handle transparently touchpad gesture events. The only precautions users of GtkGesture should do to enable this support are:

  • If the gesture has GTK_PHASE_NONE, ensuring events of type GDK_TOUCHPAD_SWIPE and GDK_TOUCHPAD_PINCH are handled by the GtkGesture.


hierarchy this GtkGesture ancestor_0 GtkEventController ancestor_0--this ancestor_1 GObject ancestor_1--ancestor_0

Instance methods


If there are touch sequences being currently handled by gesture, returns TRUE and fills in rect with the bounding box containing all active touches.


If there are touch sequences being currently handled by gesture, returns TRUE and fills in x and y with the center of the bounding box containing all active touches.


Returns the logical GdkDevice that is currently operating on gesture.


Returns all gestures in the group of gesture.


Returns the last event that was processed for sequence.


Returns the GdkEventSequence that was last updated on gesture.


If sequence is currently being interpreted by gesture, returns TRUE and fills in x and y with the last coordinates stored for that event sequence.


Returns the sequence state, as seen by gesture.


Returns the list of GdkEventSequences currently being interpreted by gesture.


Adds gesture to the same group than group_gesture.


Returns TRUE if gesture is currently handling events corresponding to sequence.


Returns TRUE if the gesture is currently active.


Returns TRUE if both gestures pertain to the same group.


Returns TRUE if the gesture is currently recognized.


Sets the state of sequence in gesture.

deprecated: 4.10. 


Sets the state of all sequences that gesture is currently interacting with.


Separates gesture into an isolated group.

Methods inherited from GtkEventController (13)

Returns the event that is currently being handled by the controller.


Returns the device of the event that is currently being handled by the controller.


Returns the modifier state of the event that is currently being handled by the controller.


Returns the timestamp of the event that is currently being handled by the controller.


Gets the name of controller.


Gets the propagation limit of the event controller.


Gets the propagation phase at which controller handles events.


Returns the GtkWidget this controller relates to.


Resets the controller to a clean state.


Sets a name on the controller that can be used for debugging.


Sets the event propagation limit on the event controller.


Sets the propagation phase at which a controller handles events.


Sets a name on the controller that can be used for debugging.

since: 4.8

Methods inherited from GObject (43)

Please see GObject for a full list of methods.



The number of touch points that trigger recognition on this gesture.

Properties inherited from GtkEventController (4)

The name for this controller, typically used for debugging purposes.


The limit for which events this controller will handle.


The propagation phase at which this controller will handle events.


The widget receiving the GdkEvents that the controller will handle.



Emitted when the gesture is recognized.


Emitted whenever a sequence is cancelled.


Emitted when gesture either stopped recognizing the event sequences as something to be handled, or the number of touch sequences became higher or lower than GtkGesture:n-points.


Emitted whenever a sequence state changes.


Emitted whenever an event is handled while the gesture is recognized.

Signals inherited from GObject (1)

The notify signal is emitted on an object when one of its properties has its value set through g_object_set_property(), g_object_set(), et al.

Class structure

struct GtkGestureClass {
  /* no available fields */

No description available.