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 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 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: - begin when the gesture is recognized. - A number of update, whenever an input event is processed. - 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 button-press-event, button-release-event, touch-event, etc signals. Gestures with the GTK_PHASE_TARGET phase are fed events from the default 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-state|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 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 {}

Constructors

this
this(GtkGesture* gtkGesture, bool ownedRef = false)

Sets our main struct and passes it to the parent class.

Members

Functions

addOnBegin
gulong addOnBegin(void delegate(GdkEventSequence*, Gesture) dlg, ConnectFlags connectFlags = cast(ConnectFlags)0)

This signal is emitted when the gesture is recognized. This means the number of touch sequences matches n-points, and the check handler(s) returned TRUE

addOnBegin
gulong addOnBegin(void delegate(Event, Gesture) dlg, ConnectFlags connectFlags = cast(ConnectFlags)0)

This signal is emitted when the gesture is recognized. This means the number of touch sequences matches n-points, and the check handler(s) returned TRUE

addOnCancel
gulong addOnCancel(void delegate(GdkEventSequence*, Gesture) dlg, ConnectFlags connectFlags = cast(ConnectFlags)0)

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 = cast(ConnectFlags)0)

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 = cast(ConnectFlags)0)

This signal is emitted when gesture either stopped recognizing the event sequences as something to be handled (the check handler returned FALSE), or the number of touch sequences became higher or lower than n-points.

addOnEnd
gulong addOnEnd(void delegate(Event, Gesture) dlg, ConnectFlags connectFlags = cast(ConnectFlags)0)

This signal is emitted when gesture either stopped recognizing the event sequences as something to be handled (the check handler returned FALSE), or the number of touch sequences became higher or lower than n-points.

addOnSequenceStateChanged
gulong addOnSequenceStateChanged(void delegate(GdkEventSequence*, GtkEventSequenceState, Gesture) dlg, ConnectFlags connectFlags = cast(ConnectFlags)0)

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 = cast(ConnectFlags)0)

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 = cast(ConnectFlags)0)

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 = cast(ConnectFlags)0)

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(out 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(out double x, out 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 = false)

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, out double x, out 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 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