Gesture

#GtkGesture 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 %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 wether the gesture is recognized.

As soon as the gesture has the expected number of touches, the gesture will run the #GtkGesture::check signal regularly on input events until the gesture is recognized, the criteria to consider a gesture as "recognized" is left to #GtkGesture subclasses.

A recognized gesture will then emit the following signals: - #GtkGesture::begin when the gesture is recognized. - A number of #GtkGesture::update, whenever an input event is processed. - #GtkGesture::end when the gesture is no longer recognized.

Event propagation

In order to receive events, a gesture needs to either set a propagation phase through gtk_event_controller_set_propagation_phase(), or feed those manually through gtk_event_controller_handle_event().

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.

After the capture phase, GTK+ emits the traditional #GtkWidget::button-press-event, #GtkWidget::button-release-event, #GtkWidget::touch-event, etc signals. Gestures with the %GTK_PHASE_TARGET phase are fed events from the default #GtkWidget::event handlers.

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 # {#touch-sequence-states}

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_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. - calling #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 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_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: - Enabling %GDK_TOUCHPAD_GESTURE_MASK on their #GdkWindows - 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();

Window getWindow();

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 setWindow(Window window);

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): This signal is emitted when the gesture is recognized. This means the number of touch sequences matches #GtkGesture:n-points, and the #GtkGesture::check handler(s) returned #TRUE.
addOnBegin gulong addOnBegin(void delegate(Event, Gesture) dlg, ConnectFlags connectFlags): This signal is emitted when the gesture is recognized. This means the number of touch sequences matches #GtkGesture:n-points, and the #GtkGesture::check handler(s) returned #TRUE.
addOnCancel gulong addOnCancel(void delegate(GdkEventSequence*, Gesture) dlg, ConnectFlags connectFlags): This signal is emitted whenever a sequence is cancelled. This usually happens on active touches when gtk_event_controller_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()).
addOnCancel gulong addOnCancel(void delegate(Event, Gesture) dlg, ConnectFlags connectFlags): This signal is emitted whenever a sequence is cancelled. This usually happens on active touches when gtk_event_controller_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()).
addOnEnd gulong addOnEnd(void delegate(GdkEventSequence*, Gesture) dlg, ConnectFlags connectFlags): This signal is emitted when @gesture either stopped recognizing the event sequences as something to be handled (the #GtkGesture::check handler returned %FALSE), or the number of touch sequences became higher or lower than #GtkGesture:n-points.
addOnEnd gulong addOnEnd(void delegate(Event, Gesture) dlg, ConnectFlags connectFlags): This signal is emitted when @gesture either stopped recognizing the event sequences as something to be handled (the #GtkGesture::check handler returned %FALSE), or the number of touch sequences became higher or lower than #GtkGesture:n-points.
addOnSequenceStateChanged gulong addOnSequenceStateChanged(void delegate(GdkEventSequence*, GtkEventSequenceState, Gesture) dlg, ConnectFlags connectFlags): This signal is emitted whenever a sequence state changes. See gtk_gesture_set_sequence_state() to know more about the expectable sequence lifetimes.
addOnSequenceStateChanged gulong addOnSequenceStateChanged(void delegate(Event, GtkEventSequenceState, Gesture) dlg, ConnectFlags connectFlags): This signal is emitted whenever a sequence state changes. See gtk_gesture_set_sequence_state() to know more about the expectable sequence lifetimes.
addOnUpdate gulong addOnUpdate(void delegate(GdkEventSequence*, Gesture) dlg, ConnectFlags connectFlags): This signal is emitted whenever an event is handled while the gesture is recognized. @sequence is guaranteed to pertain to the set of active touches.
addOnUpdate gulong addOnUpdate(void delegate(Event, Gesture) dlg, ConnectFlags connectFlags): This signal is emitted whenever an event is handled while the gesture is recognized. @sequence is guaranteed to pertain to the set of active touches.
getBoundingBox bool getBoundingBox(GdkRectangle rect): If there are touch sequences being currently handled by @gesture, this function returns %TRUE and fills in @rect with the bounding box containing all active touches. Otherwise, %FALSE will be returned.
getBoundingBoxCenter bool getBoundingBoxCenter(double x, double y): If there are touch sequences being currently handled by @gesture, this function returns %TRUE and fills in @x and @y with the center of the bounding box containing all active touches. Otherwise, %FALSE will be returned.
getDevice Device getDevice(): Returns the master #GdkDevice that is currently operating on @gesture, or %NULL if the gesture is not being interacted.
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, this function 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.
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*
getWindow Window getWindow(): Returns the user-defined window that receives the events handled by @gesture. See gtk_gesture_set_window() for more information.
group void group(Gesture gesture): Adds @gesture to the same group than @group_gesture. Gestures are by default isolated in their own groups.
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. A gesture is active meanwhile there are touch sequences interacting with it.
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. A gesture is recognized if there are as many interacting touch sequences as required by @gesture, and #GtkGesture::check returned %TRUE for the sequences being currently interpreted.
setSequenceState bool setSequenceState(GdkEventSequence* sequence, GtkEventSequenceState state): Sets the state of @sequence in @gesture. Sequences start in state #GTK_EVENT_SEQUENCE_NONE, and whenever they change state, they can never go back to that state. Likewise, sequences in state #GTK_EVENT_SEQUENCE_DENIED cannot turn back to a not denied state. With these rules, the lifetime of an event sequence is constrained to the next four:
setState bool setState(GtkEventSequenceState state): Sets the state of all sequences that @gesture is currently interacting with. See gtk_gesture_set_sequence_state() for more details on sequence states.
setWindow void setWindow(Window window): Sets a specific window to receive events about, so @gesture will effectively handle only events targeting @window, or a child of it. @window must pertain to gtk_event_controller_get_widget().
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()
getPropagationPhase GtkPropagationPhase getPropagationPhase(): Gets the propagation phase at which @controller handles events.
getWidget Widget getWidget(): Returns the #GtkWidget this controller relates to.
handleEvent bool handleEvent(Event event): Feeds an events into @controller, so it can be interpreted and the controller actions triggered.
reset void reset(): Resets the @controller to a clean state. Every interaction the controller did through #GtkEventController::handle-event will be dropped at this point.
setPropagationPhase void setPropagationPhase(GtkPropagationPhase phase): Sets the propagation phase at which a controller handles events.