Gesture

class Gesture(**properties: Any)

Superclasses: EventController, Object

Subclasses: GestureRotate, GestureSingle, GestureZoom

Constructors:

Gesture(**properties)

Methods

class Gesture

get_bounding_box() → tuple[bool, Rectangle]

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

Otherwise, False will be returned.

Note: This function will yield unexpected results on touchpad gestures. Since there is no correlation between physical and pixel distances, these will look as if constrained in an infinitely small area, rect width and height will thus be 0 regardless of the number of touchpoints.

get_bounding_box_center() → tuple[bool, float, float]

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.

Otherwise, False will be returned.

get_device() → Device | None

Returns the logical GdkDevice that is currently operating on gesture.

This returns None if the gesture is not being interacted.

get_group() → list[Gesture]

Returns all gestures in the group of gesture

get_last_event(sequence: EventSequence | None = None) → Event | None

Returns the last event that was processed for sequence.

Note that the returned pointer is only valid as long as the sequence is still interpreted by the gesture. If in doubt, you should make a copy of the event.

Parameters:

sequence – a GdkEventSequence

get_last_updated_sequence() → EventSequence | None

Returns the GdkEventSequence that was last updated on gesture.

get_point(sequence: EventSequence | None = None) → tuple[bool, float, float]

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.

The coordinates are always relative to the widget allocation.

Parameters:

sequence – a GdkEventSequence, or None for pointer events

get_sequence_state(sequence: EventSequence) → EventSequenceState

Returns the sequence state, as seen by gesture.

Parameters:

sequence – a GdkEventSequence

get_sequences() → list[EventSequence]

Returns the list of GdkEventSequences currently being interpreted by gesture.

group(gesture: Gesture) → None

Adds gesture to the same group than group_gesture.

Gestures are by default isolated in their own groups.

Both gestures must have been added to the same widget before they can be grouped.

When gestures are grouped, the state of GdkEventSequences is kept in sync for all of those, so calling set_sequence_state, on one will transfer the same value to the others.

Groups also perform an “implicit grabbing” of sequences, if a GdkEventSequence state is set to CLAIMED on one group, every other gesture group attached to the same GtkWidget will switch the state for that sequence to DENIED.

Parameters:

gesture – a GtkGesture

handles_sequence(sequence: EventSequence | None = None) → bool

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

Parameters:

sequence – a GdkEventSequence

is_active() → bool

Returns True if the gesture is currently active.

A gesture is active while there are touch sequences interacting with it.

is_grouped_with(other: Gesture) → bool

Returns True if both gestures pertain to the same group.

Parameters:

other – another GtkGesture

is_recognized() → bool

Returns True if the gesture is currently recognized.

A gesture is recognized if there are as many interacting touch sequences as required by gesture.

set_sequence_state(sequence: EventSequence, state: EventSequenceState) → bool

Sets the state of sequence in gesture.

Sequences start in state NONE, and whenever they change state, they can never go back to that state. Likewise, sequences in state DENIED cannot turn back to a not denied state. With these rules, the lifetime of an event sequence is constrained to the next four:

• None

• None → Denied

• None → Claimed

• None → Claimed → Denied

Note: Due to event handling ordering, it may be unsafe to set the state on another gesture within a begin signal handler, as the callback might be executed before the other gesture knows about the sequence. A safe way to perform this could be:

static void
first_gesture_begin_cb (GtkGesture       *first_gesture,
                        GdkEventSequence *sequence,
                        gpointer          user_data)
{
  gtk_gesture_set_sequence_state (first_gesture, sequence, GTK_EVENT_SEQUENCE_CLAIMED);
  gtk_gesture_set_sequence_state (second_gesture, sequence, GTK_EVENT_SEQUENCE_DENIED);
}

static void
second_gesture_begin_cb (GtkGesture       *second_gesture,
                         GdkEventSequence *sequence,
                         gpointer          user_data)
{
  if (gtk_gesture_get_sequence_state (first_gesture, sequence) == GTK_EVENT_SEQUENCE_CLAIMED)
    gtk_gesture_set_sequence_state (second_gesture, sequence, GTK_EVENT_SEQUENCE_DENIED);
}

If both gestures are in the same group, just set the state on the gesture emitting the event, the sequence will be already be initialized to the group’s global state when the second gesture processes the event.

Deprecated since version 4.10.: Use set_state

Parameters:

• sequence – a GdkEventSequence

• state – the sequence state

set_state(state: EventSequenceState) → bool

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

Sequences start in state NONE, and whenever they change state, they can never go back to that state. Likewise, sequences in state DENIED cannot turn back to a not denied state. With these rules, the lifetime of an event sequence is constrained to the next four:

• None

• None → Denied

• None → Claimed

• None → Claimed → Denied

Note: Due to event handling ordering, it may be unsafe to set the state on another gesture within a begin signal handler, as the callback might be executed before the other gesture knows about the sequence. A safe way to perform this could be:

static void
first_gesture_begin_cb (GtkGesture       *first_gesture,
                        GdkEventSequence *sequence,
                        gpointer          user_data)
{
  gtk_gesture_set_state (first_gesture, GTK_EVENT_SEQUENCE_CLAIMED);
  gtk_gesture_set_state (second_gesture, GTK_EVENT_SEQUENCE_DENIED);
}

static void
second_gesture_begin_cb (GtkGesture       *second_gesture,
                         GdkEventSequence *sequence,
                         gpointer          user_data)
{
  if (gtk_gesture_get_sequence_state (first_gesture, sequence) == GTK_EVENT_SEQUENCE_CLAIMED)
    gtk_gesture_set_state (second_gesture, GTK_EVENT_SEQUENCE_DENIED);
}

If both gestures are in the same group, just set the state on the gesture emitting the event, the sequence will be already be initialized to the group’s global state when the second gesture processes the event.

Parameters:

state – the sequence state

ungroup() → None

Separates gesture into an isolated group.

Properties

class Gesture

props.n_points: int

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

Signals

class Gesture.signals

begin(sequence: EventSequence | None = None) → None

Emitted when the gesture is recognized.

This means the number of touch sequences matches n_points.

Note: These conditions may also happen when an extra touch (eg. a third touch on a 2-touches gesture) is lifted, in that situation sequence won’t pertain to the current set of active touches, so don’t rely on this being true.

Parameters:

sequence – the GdkEventSequence that made the gesture to be recognized

cancel(sequence: EventSequence | None = None) → None

Emitted whenever a sequence is cancelled.

This usually happens on active touches when reset is called on gesture (manually, due to grabs…), or the individual sequence was claimed by parent widgets’ controllers (see set_sequence_state).

gesture must forget everything about sequence as in response to this signal.

Parameters:

sequence – the GdkEventSequence that was cancelled

end(sequence: EventSequence | None = None) → None

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 n_points.

Note: sequence might not pertain to the group of sequences that were previously triggering recognition on gesture (ie. a just pressed touch sequence that exceeds n_points). This situation may be detected by checking through handles_sequence.

Parameters:

sequence – the GdkEventSequence that made gesture recognition to finish

sequence_state_changed(sequence: EventSequence | None, state: EventSequenceState) → None

Emitted whenever a sequence state changes.

See set_sequence_state to know more about the expectable sequence lifetimes.

Parameters:

• sequence – the GdkEventSequence that was cancelled

• state – the new sequence state

update(sequence: EventSequence | None = None) → None

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

sequence is guaranteed to pertain to the set of active touches.

Parameters:

sequence – the GdkEventSequence that was updated