gtkmm: Gtk::Gesture Class Reference

Abstract base class for gestures. More...

#include <gtkmm/gesture.h>

Inheritance diagram for Gtk::Gesture:

[legend]

Public Member Functions
	Gesture (Gesture && src) noexcept

Gesture &	operator= (Gesture && src) noexcept

	~Gesture () noexcept override

GtkGesture *	gobj ()
	Provides access to the underlying C GObject. More...

const GtkGesture *	gobj () const
	Provides access to the underlying C GObject. More...

GtkGesture *	gobj_copy ()
	Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs. More...

Glib::RefPtr< Gdk::Device >	get_device ()
	Returns the logical `Gdk::Device` that is currently operating on gesture. More...

Glib::RefPtr< const Gdk::Device >	get_device () const
	Returns the logical `Gdk::Device` that is currently operating on gesture. More...

bool	set_state (EventSequenceState state)
	Sets the state of all sequences that gesture is currently interacting with. More...

EventSequenceState	get_sequence_state (Gdk::EventSequence * sequence) const
	Returns the sequence state, as seen by gesture. More...

bool	set_sequence_state (Gdk::EventSequence * sequence, EventSequenceState state)
	Sets the state of sequence in gesture. More...

std::vector< const Gdk::EventSequence * >	get_sequences () const
	Returns the list of Gdk::EventSequences currently being interpreted. More...

Gdk::EventSequence *	get_last_updated_sequence ()
	Returns the `Gdk::EventSequence` that was last updated on gesture. More...

const Gdk::EventSequence *	get_last_updated_sequence () const
	Returns the `Gdk::EventSequence` that was last updated on gesture. More...

bool	handles_sequence (Gdk::EventSequence * sequence) const
	Returns `true` if gesture is currently handling events corresponding to sequence. More...

Glib::RefPtr< Gdk::Event >	get_last_event (Gdk::EventSequence * sequence)
	Returns the last event that was processed for sequence. More...

Glib::RefPtr< const Gdk::Event >	get_last_event (Gdk::EventSequence * sequence) const
	Returns the last event that was processed for sequence. More...

bool	get_point (Gdk::EventSequence * sequence, double & x, double & y) const
	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. More...

bool	get_bounding_box (Gdk::Rectangle & rect) const
	If there are touch sequences being currently handled by gesture, returns `true` and fills in rect with the bounding box containing all active touches. More...

bool	get_bounding_box_center (double & x, double & y) const
	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. More...

bool	is_active () const
	Returns `true` if the gesture is currently active. More...

bool	is_recognized () const
	Returns `true` if the gesture is currently recognized. More...

void	group (const Glib::RefPtr< Gesture > & group_gesture)
	Adds gesture to the same group than group_gesture. More...

void	ungroup ()
	Separates gesture into an isolated group. More...

std::vector< Glib::RefPtr< Gesture > >	get_group ()
	Returns all gestures in the group of gesture. More...

std::vector< Glib::RefPtr< const Gesture > >	get_group () const
	Returns all gestures in the group of gesture. More...

bool	is_grouped_with (const Glib::RefPtr< Gesture > & other) const
	Returns `true` if both gestures pertain to the same group. More...

Glib::SignalProxy< void(Gdk::EventSequence *)>	signal_begin ()

Glib::SignalProxy< void(Gdk::EventSequence *)>	signal_end ()

Glib::SignalProxy< void(Gdk::EventSequence *)>	signal_update ()

Glib::SignalProxy< void(Gdk::EventSequence *)>	signal_cancel ()

Glib::SignalProxy< void(Gdk::EventSequence *, EventSequenceState)>	signal_sequence_state_changed ()

Glib::PropertyProxy_ReadOnly< unsigned int >	property_n_points () const
	The number of touch points that trigger recognition on this gesture. More...

Public Member Functions inherited from Gtk::EventController
	EventController (EventController && src) noexcept

EventController &	operator= (EventController && src) noexcept

	~EventController () noexcept override

GtkEventController *	gobj ()
	Provides access to the underlying C GObject. More...

const GtkEventController *	gobj () const
	Provides access to the underlying C GObject. More...

GtkEventController *	gobj_copy ()
	Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs. More...

Widget *	get_widget ()
	Returns the `Gtk::Widget` this controller relates to. More...

const Widget *	get_widget () const
	Returns the `Gtk::Widget` this controller relates to. More...

void	reset ()
	Resets the controller to a clean state. More...

PropagationPhase	get_propagation_phase () const
	Gets the propagation phase at which controller handles events. More...

void	set_propagation_phase (PropagationPhase phase)
	Sets the propagation phase at which a controller handles events. More...

PropagationLimit	get_propagation_limit () const
	Gets the propagation limit of the event controller. More...

void	set_propagation_limit (PropagationLimit limit)
	Sets the event propagation limit on the event controller. More...

Glib::ustring	get_name () const
	Gets the name of controller. More...

void	set_name (const Glib::ustring & name)
	Sets a name on the controller that can be used for debugging. More...

Glib::RefPtr< const Gdk::Event >	get_current_event () const
	Returns the event that is currently being handled by the controller. More...

guint32	get_current_event_time () const
	Returns the timestamp of the event that is currently being handled by the controller. More...

Glib::RefPtr< Gdk::Device >	get_current_event_device ()
	Returns the device of the event that is currently being handled by the controller. More...

Glib::RefPtr< const Gdk::Device >	get_current_event_device () const
	Returns the event that is currently being handled by the controller. More...

Gdk::ModifierType	get_current_event_state () const
	Returns the modifier state of the event that is currently being handled by the controller. More...

Glib::PropertyProxy_ReadOnly< Widget * >	property_widget () const
	The widget receiving the `Gdk::Events` that the controller will handle. More...

Glib::PropertyProxy< PropagationPhase >	property_propagation_phase ()
	The propagation phase at which this controller will handle events. More...

Glib::PropertyProxy_ReadOnly< PropagationPhase >	property_propagation_phase () const
	The propagation phase at which this controller will handle events. More...

Glib::PropertyProxy< PropagationLimit >	property_propagation_limit ()
	The limit for which events this controller will handle. More...

Glib::PropertyProxy_ReadOnly< PropagationLimit >	property_propagation_limit () const
	The limit for which events this controller will handle. More...

Glib::PropertyProxy< Glib::ustring >	property_name ()
	The name for this controller, typically used for debugging purposes. More...

Glib::PropertyProxy_ReadOnly< Glib::ustring >	property_name () const
	The name for this controller, typically used for debugging purposes. More...

Static Public Member Functions
static GType	get_type ()
	Get the GType for this class, for use with the underlying GObject type system. More...

Static Public Member Functions inherited from Gtk::EventController
static GType	get_type ()
	Get the GType for this class, for use with the underlying GObject type system. More...

Protected Member Functions
	Gesture ()
	There is no create() method that corresponds to this constructor, because only derived classes shall be created. More...

Protected Member Functions inherited from Gtk::EventController
	EventController ()
	There is no create() method that corresponds to this constructor, because only derived classes shall be created. More...

Related Functions
(Note that these are not member functions.)
Glib::RefPtr< Gtk::Gesture >	wrap (GtkGesture * object, bool take_copy=false)
	A Glib::wrap() method for this object. More...

Related Functions inherited from Gtk::EventController
Glib::RefPtr< Gtk::EventController >	wrap (GtkEventController * object, bool take_copy=false)
	A Glib::wrap() method for this object. More...

Detailed Description

Abstract base class for gestures.

This is the base object for gesture recognition. Although this object 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 Gdk::EventSequence value for these).

The number of touches that a Gesture need to be recognized is controlled by the 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 Gesture subclasses.

A recognized gesture will then emit the following signals:

signal_begin() when the gesture is recognized.
A number of signal_update(), whenever an input event is processed.
signal_end() when the gesture is no longer recognized.

Event propagation

In order to receive events, a gesture needs to set a propagation phase through EventController::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 Gestures, both across the parents of the widget receiving the event and parallelly 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 Gdk::EventSequences triggering those.

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

By default, all sequences start out in the Gtk::EventSequenceState::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::EventSequenceState::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::EventSequenceState::CLAIMED state, the gesture group will grab all interaction on the sequence, by:

Setting the same sequence to Gtk::EventSequenceState::DENIED on every other gesture group within the widget, and every gesture on parent widgets in the propagation chain.
emitting signal_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::EventSequenceState::CLAIMED on Gdk::Event::Type::TOUCH_BEGIN / Gdk::Event::Type::BUTTON_PRESS (so those events are captured before reaching the event widget, this implies Gtk::PropagationPhase::CAPTURE), one similar event will be emulated if the sequence changes to Gtk::EventSequenceState::DENIED. This way event coherence is preserved before event propagation is unstopped again.

Sequence states can't be changed freely, see set_sequence_state() to know about the possible lifetimes of a Gdk::EventSequence.

Since gtkmm 3.14:

Constructor & Destructor Documentation

◆ Gesture() [1/2]

Gtk::Gesture::Gesture ( Gesture && src )

noexcept

◆ ~Gesture()

Gtk::Gesture::~Gesture ( )

overridenoexcept

◆ Gesture() [2/2]

Gtk::Gesture::Gesture ( )

protected

There is no create() method that corresponds to this constructor, because only derived classes shall be created.

Member Function Documentation

◆ get_bounding_box()

bool Gtk::Gesture::get_bounding_box ( Gdk::Rectangle & rect ) const

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.

Parameters

rect	Bounding box containing all active touches.

Returns: true if there are active touches, false otherwise.

◆ get_bounding_box_center()

bool Gtk::Gesture::get_bounding_box_center	(	double &	x,
		double &	y
	)		const

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.

Parameters

x	X coordinate for the bounding box center.
y	Y coordinate for the bounding box center.

Returns: false if no active touches are present, true otherwise.

◆ get_device() [1/2]

Glib::RefPtr< Gdk::Device > Gtk::Gesture::get_device ( )

Returns the logical Gdk::Device that is currently operating on gesture.

This returns nullptr if the gesture is not being interacted.

Returns: A Gdk::Device.

◆ get_device() [2/2]

Glib::RefPtr< const Gdk::Device > Gtk::Gesture::get_device ( ) const

Returns the logical Gdk::Device that is currently operating on gesture.

This returns nullptr if the gesture is not being interacted.

Returns: A Gdk::Device.

◆ get_group() [1/2]

std::vector< Glib::RefPtr< Gesture > > Gtk::Gesture::get_group ( )

Returns all gestures in the group of gesture.

Returns: The list of Gtk::Gestures.

◆ get_group() [2/2]

std::vector< Glib::RefPtr< const Gesture > > Gtk::Gesture::get_group ( ) const

Returns all gestures in the group of gesture.

Returns: The list of Gtk::Gestures.

◆ get_last_event() [1/2]

Glib::RefPtr< Gdk::Event > Gtk::Gesture::get_last_event ( Gdk::EventSequence * sequence )

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 Gdk::EventSequence.

Returns: The last event from sequence.

◆ get_last_event() [2/2]

Glib::RefPtr< const Gdk::Event > Gtk::Gesture::get_last_event ( Gdk::EventSequence * sequence ) const

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 Gdk::EventSequence.

Returns: The last event from sequence.

◆ get_last_updated_sequence() [1/2]

Gdk::EventSequence * Gtk::Gesture::get_last_updated_sequence ( )

Returns the Gdk::EventSequence that was last updated on gesture.

Returns: The last updated sequence.

◆ get_last_updated_sequence() [2/2]

const Gdk::EventSequence * Gtk::Gesture::get_last_updated_sequence ( ) const

Returns the Gdk::EventSequence that was last updated on gesture.

Returns: The last updated sequence.

◆ get_point()

bool Gtk::Gesture::get_point	(	Gdk::EventSequence *	sequence,
		double &	x,
		double &	y
	)		const

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 `Gdk::EventSequence`, or `nullptr` for pointer events.
x	Return location for X axis of the sequence coordinates.
y	Return location for Y axis of the sequence coordinates.

Returns: true if sequence is currently interpreted.

◆ get_sequence_state()

EventSequenceState Gtk::Gesture::get_sequence_state ( Gdk::EventSequence * sequence ) const

Returns the sequence state, as seen by gesture.

Parameters

sequence A Gdk::EventSequence.

Returns: The sequence state in gesture.

◆ get_sequences()

std::vector< const Gdk::EventSequence * > Gtk::Gesture::get_sequences ( ) const

Returns the list of Gdk::EventSequences currently being interpreted.

Since gtkmm 3.14:

Returns: A std::vector of Gdk::EventSequence pointers. The Gdk::EventSequences are owned by GTK+ and must not be freed or modified.

◆ get_type()

static GType Gtk::Gesture::get_type ( )

static

Get the GType for this class, for use with the underlying GObject type system.

◆ gobj() [1/2]

GtkGesture * Gtk::Gesture::gobj ( )

inline

Provides access to the underlying C GObject.

◆ gobj() [2/2]

const GtkGesture * Gtk::Gesture::gobj ( ) const

inline

Provides access to the underlying C GObject.

◆ gobj_copy()

GtkGesture * Gtk::Gesture::gobj_copy ( )

Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs.

◆ group()

void Gtk::Gesture::group ( const Glib::RefPtr< Gesture > & group_gesture )

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 Gdk::EventSequences 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 Gdk::EventSequence state is set to Gtk::EventSequenceState::CLAIMED on one group, every other gesture group attached to the same Gtk::Widget will switch the state for that sequence to Gtk::EventSequenceState::DENIED.

Parameters

group_gesture Gtk::Gesture to group gesture with.

◆ handles_sequence()

bool Gtk::Gesture::handles_sequence ( Gdk::EventSequence * sequence ) const

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

Parameters

sequence A Gdk::EventSequence.

Returns: true if gesture is handling sequence, false otherwise.

◆ is_active()

bool Gtk::Gesture::is_active ( ) const

Returns true if the gesture is currently active.

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

Returns: true if gesture is active.

◆ is_grouped_with()

bool Gtk::Gesture::is_grouped_with ( const Glib::RefPtr< Gesture > & other ) const

Returns true if both gestures pertain to the same group.

Parameters

other Another Gtk::Gesture.

Returns: Whether the gestures are grouped.

◆ is_recognized()

bool Gtk::Gesture::is_recognized ( ) const

Returns true if the gesture is currently recognized.

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

Returns: true if gesture is recognized.

◆ operator=()

Gesture & Gtk::Gesture::operator= ( Gesture && src )

noexcept

◆ property_n_points()

Glib::PropertyProxy_ReadOnly< unsigned int > Gtk::Gesture::property_n_points ( ) const

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

Default value: 1

Returns: A PropertyProxy_ReadOnly that allows you to get the value of the property, or receive notification when the value of the property changes.

◆ set_sequence_state()

bool Gtk::Gesture::set_sequence_state	(	Gdk::EventSequence *	sequence,
		EventSequenceState	state
	)

Sets the state of sequence in gesture.

Sequences start in state Gtk::EventSequenceState::NONE, and whenever they change state, they can never go back to that state. Likewise, sequences in state Gtk::EventSequenceState::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 signal_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:

[C example ellipted]

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: 4.10. Use set_state()

Deprecated:: Use set_state() instead.

Parameters

sequence	A `Gdk::EventSequence`.
state	The sequence state.

Returns: true if sequence is handled by gesture, and the state is changed successfully.

◆ set_state()

bool Gtk::Gesture::set_state ( EventSequenceState state )

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

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 signal_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:

[C example ellipted]

Parameters

state The sequence state.

Returns: true if the state of at least one sequence was changed successfully.

◆ signal_begin()

Glib::SignalProxy< void(Gdk::EventSequence *)> Gtk::Gesture::signal_begin ( )

Slot Prototype:: void on_my_begin(Gdk::EventSequence* sequence)

Flags: Run Last

Emitted when the gesture is recognized.

This means the number of touch sequences matches property_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 Gdk::EventSequence that made the gesture to be recognized.

◆ signal_cancel()

Glib::SignalProxy< void(Gdk::EventSequence *)> Gtk::Gesture::signal_cancel ( )

Slot Prototype:: void on_my_cancel(Gdk::EventSequence* sequence)

Flags: Run Last

Emitted whenever a sequence is cancelled.

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

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

Parameters

sequence The Gdk::EventSequence that was cancelled.

◆ signal_end()

Glib::SignalProxy< void(Gdk::EventSequence *)> Gtk::Gesture::signal_end ( )

Slot Prototype:: void on_my_end(Gdk::EventSequence* sequence)

Flags: Run Last

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 property_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 property_n_points()). This situation may be detected by checking through Gtk::Gesture::handles_sequence().

Parameters

sequence The Gdk::EventSequence that made gesture recognition to finish.

◆ signal_sequence_state_changed()

Glib::SignalProxy< void(Gdk::EventSequence *, EventSequenceState)> Gtk::Gesture::signal_sequence_state_changed ( )

Slot Prototype:: void on_my_sequence_state_changed(Gdk::EventSequence* sequence, EventSequenceState state)

Flags: Run Last

Emitted whenever a sequence state changes.

See Gtk::Gesture::set_sequence_state() to know more about the expectable sequence lifetimes.

Parameters

sequence	The `Gdk::EventSequence` that was cancelled.
state	The new sequence state.

◆ signal_update()

Glib::SignalProxy< void(Gdk::EventSequence *)> Gtk::Gesture::signal_update ( )

Slot Prototype:: void on_my_update(Gdk::EventSequence* sequence)

Flags: Run Last

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 Gdk::EventSequence that was updated.

◆ ungroup()

void Gtk::Gesture::ungroup ( )

Separates gesture into an isolated group.

Friends And Related Function Documentation

◆ wrap()

Glib::RefPtr< Gtk::Gesture > wrap	(	GtkGesture *	object,
		bool	take_copy = `false`
	)

A Glib::wrap() method for this object.

Parameters

object	The C instance.
take_copy	False if the result should take ownership of the C instance. True if it should take a new copy or ref.

Returns: A C++ instance that wraps this C instance.

Public Member Functions

Static Public Member Functions

Protected Member Functions

Related Functions

Detailed Description

Event propagation

States of a sequence

Constructor & Destructor Documentation

◆ Gesture() [1/2]

◆ ~Gesture()

◆ Gesture() [2/2]

Member Function Documentation

◆ get_bounding_box()

◆ get_bounding_box_center()

◆ get_device() [1/2]

◆ get_device() [2/2]

◆ get_group() [1/2]

◆ get_group() [2/2]

◆ get_last_event() [1/2]

◆ get_last_event() [2/2]

◆ get_last_updated_sequence() [1/2]

◆ get_last_updated_sequence() [2/2]

◆ get_point()

◆ get_sequence_state()

◆ get_sequences()

◆ get_type()

◆ gobj() [1/2]

◆ gobj() [2/2]

◆ gobj_copy()

◆ group()

◆ handles_sequence()

◆ is_active()

◆ is_grouped_with()

◆ is_recognized()

◆ operator=()

◆ property_n_points()

◆ set_sequence_state()

◆ set_state()

◆ signal_begin()

◆ signal_cancel()

◆ signal_end()

◆ signal_sequence_state_changed()

◆ signal_update()

◆ ungroup()

Friends And Related Function Documentation

◆ wrap()