Gesture

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 [property@Gtk.Gesture: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:

- [signal@Gtk.Gesture::begin] when the gesture is recognized. - [signal@Gtk.Gesture::update], whenever an input event is processed. - [signal@Gtk.Gesture::end] when the gesture is no longer recognized.

Event propagation

In order to receive events, a gesture needs to set a propagation phase through [method@Gtk.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 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 [method@Gtk.Gesture.group]. Grouped gestures synchronize the state of sequences, so calling [method@Gtk.Gesture.set_sequence_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 [signal@Gtk.Gesture::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 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 [method@Gtk.Gesture.set_sequence_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

class Gesture : EventController {

protected

GtkGesture* gtkGesture;

GtkGesture* getGestureStruct(bool transferOwnership);

void* getStruct();

this(GtkGesture* gtkGesture, bool ownedRef);

static GType getType();

bool getBoundingBox(GdkRectangle rect);

bool getBoundingBoxCenter(double x, double y);

Device getDevice();

ListG getGroup();

Event getLastEvent(GdkEventSequence* sequence);

GdkEventSequence* getLastUpdatedSequence();

bool getPoint(GdkEventSequence* sequence, double x, double y);

GtkEventSequenceState getSequenceState(GdkEventSequence* sequence);

ListG getSequences();

void group(Gesture gesture);

bool handlesSequence(GdkEventSequence* sequence);

bool isActive();

bool isGroupedWith(Gesture other);

bool isRecognized();

bool setSequenceState(GdkEventSequence* sequence, GtkEventSequenceState state);

bool setState(GtkEventSequenceState state);

void ungroup();

gulong addOnBegin(void delegate(GdkEventSequence*, Gesture) dlg, ConnectFlags connectFlags);

gulong addOnBegin(void delegate(Event, Gesture) dlg, ConnectFlags connectFlags);

gulong addOnCancel(void delegate(GdkEventSequence*, Gesture) dlg, ConnectFlags connectFlags);

gulong addOnCancel(void delegate(Event, Gesture) dlg, ConnectFlags connectFlags);

gulong addOnEnd(void delegate(GdkEventSequence*, Gesture) dlg, ConnectFlags connectFlags);

gulong addOnEnd(void delegate(Event, Gesture) dlg, ConnectFlags connectFlags);

gulong addOnSequenceStateChanged(void delegate(GdkEventSequence*, GtkEventSequenceState, Gesture) dlg, ConnectFlags connectFlags);

gulong addOnSequenceStateChanged(void delegate(Event, GtkEventSequenceState, Gesture) dlg, ConnectFlags connectFlags);

gulong addOnUpdate(void delegate(GdkEventSequence*, Gesture) dlg, ConnectFlags connectFlags);

gulong addOnUpdate(void delegate(Event, Gesture) dlg, ConnectFlags connectFlags);

}

Constructors

this this(GtkGesture* gtkGesture, bool ownedRef): Sets our main struct and passes it to the parent class.

Members

Functions

addOnBegin gulong addOnBegin(void delegate(GdkEventSequence*, Gesture) dlg, ConnectFlags connectFlags): Emitted when the gesture is recognized.
addOnBegin gulong addOnBegin(void delegate(Event, Gesture) dlg, ConnectFlags connectFlags): Emitted when the gesture is recognized.
addOnCancel gulong addOnCancel(void delegate(GdkEventSequence*, Gesture) dlg, ConnectFlags connectFlags): Emitted whenever a sequence is cancelled.
addOnCancel gulong addOnCancel(void delegate(Event, Gesture) dlg, ConnectFlags connectFlags): Emitted whenever a sequence is cancelled.
addOnEnd gulong addOnEnd(void delegate(GdkEventSequence*, Gesture) dlg, ConnectFlags connectFlags): 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@Gtk.Gesture:n-points].
addOnEnd gulong addOnEnd(void delegate(Event, Gesture) dlg, ConnectFlags connectFlags): 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@Gtk.Gesture:n-points].
addOnSequenceStateChanged gulong addOnSequenceStateChanged(void delegate(GdkEventSequence*, GtkEventSequenceState, Gesture) dlg, ConnectFlags connectFlags): Emitted whenever a sequence state changes.
addOnSequenceStateChanged gulong addOnSequenceStateChanged(void delegate(Event, GtkEventSequenceState, Gesture) dlg, ConnectFlags connectFlags): Emitted whenever a sequence state changes.
addOnUpdate gulong addOnUpdate(void delegate(GdkEventSequence*, Gesture) dlg, ConnectFlags connectFlags): Emitted whenever an event is handled while the gesture is recognized.
addOnUpdate gulong addOnUpdate(void delegate(Event, Gesture) dlg, ConnectFlags connectFlags): Emitted whenever an event is handled while the gesture is recognized.
getBoundingBox bool getBoundingBox(GdkRectangle rect): If there are touch sequences being currently handled by @gesture, returns %TRUE and fills in @rect with the bounding box containing all active touches.
getBoundingBoxCenter bool getBoundingBoxCenter(double x, double y): 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.
getDevice Device getDevice(): Returns the logical GdkDevice that is currently operating on @gesture.
getGestureStruct GtkGesture* getGestureStruct(bool transferOwnership): Get the main Gtk struct
getGroup ListG getGroup(): Returns all gestures in the group of @gesture
getLastEvent Event getLastEvent(GdkEventSequence* sequence): Returns the last event that was processed for @sequence.
getLastUpdatedSequence GdkEventSequence* getLastUpdatedSequence(): Returns the GdkEventSequence that was last updated on @gesture.
getPoint bool getPoint(GdkEventSequence* sequence, double x, double y): 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.
getSequenceState GtkEventSequenceState getSequenceState(GdkEventSequence* sequence): Returns the @sequence state, as seen by @gesture.
getSequences ListG getSequences(): Returns the list of GdkEventSequences currently being interpreted by @gesture.
getStruct void* getStruct(): the main Gtk struct as a void*
group void group(Gesture gesture): Adds @gesture to the same group than @group_gesture.
handlesSequence bool handlesSequence(GdkEventSequence* sequence): Returns %TRUE if @gesture is currently handling events corresponding to @sequence.
isActive bool isActive(): Returns %TRUE if the gesture is currently active.
isGroupedWith bool isGroupedWith(Gesture other): Returns %TRUE if both gestures pertain to the same group.
isRecognized bool isRecognized(): Returns %TRUE if the gesture is currently recognized.
setSequenceState bool setSequenceState(GdkEventSequence* sequence, GtkEventSequenceState state): Sets the state of @sequence in @gesture.
setState bool setState(GtkEventSequenceState state): Sets the state of all sequences that @gesture is currently interacting with.
ungroup void ungroup(): Separates @gesture into an isolated group.

Static functions

getType GType getType()

Variables

gtkGesture GtkGesture* gtkGesture;: the main Gtk struct

Inherited Members

From EventController

gtkEventController GtkEventController* gtkEventController;: the main Gtk struct
getEventControllerStruct GtkEventController* getEventControllerStruct(bool transferOwnership): Get the main Gtk struct
getStruct void* getStruct(): the main Gtk struct as a void*
getType GType getType()
getCurrentEvent Event getCurrentEvent(): Returns the event that is currently being handled by the controller, and %NULL at other times.
getCurrentEventDevice Device getCurrentEventDevice(): Returns the device of the event that is currently being handled by the controller, and %NULL otherwise.
getCurrentEventState GdkModifierType getCurrentEventState(): Returns the modifier state of the event that is currently being handled by the controller, and 0 otherwise.
getCurrentEventTime uint getCurrentEventTime(): Returns the timestamp of the event that is currently being handled by the controller, and 0 otherwise.
getName string getName(): Gets the name of @controller.
getPropagationLimit GtkPropagationLimit getPropagationLimit(): Gets the propagation limit of the event controller.
getPropagationPhase GtkPropagationPhase getPropagationPhase(): Gets the propagation phase at which @controller handles events.
getWidget Widget getWidget(): Returns the #GtkWidget this controller relates to.
reset void reset(): Resets the @controller to a clean state.
setName void setName(string name): Sets a name on the controller that can be used for debugging.
setPropagationLimit void setPropagationLimit(GtkPropagationLimit limit): Sets the event propagation limit on the event controller.
setPropagationPhase void setPropagationPhase(GtkPropagationPhase phase): Sets the propagation phase at which a controller handles events.