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.EventController.setPropagationPhase, or feed those manually through gtk.event_controller.EventController.handleEvent.

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.types.PropagationPhase.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.Gesture.group, grouped gestures synchronize the state of sequences, so calling gtk.gesture.Gesture.setSequenceState 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.Gesture.setSequenceState 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.types.EventMask.TouchpadGestureMask on their #GdkWindows
If the gesture has gtk.types.PropagationPhase.None, ensuring events of type gdk.types.EventType.TouchpadSwipe and gdk.types.EventType.TouchpadPinch are handled by the #GtkGesture

class Gesture : EventController {

this(void* ptr, Flag!"Take" take);

static GType _getGType();

GType _gType [@property getter];

Gesture self();

static GestureGidBuilder builder();

uint nPoints [@property getter];

gdk.window.Window window [@property getter];

gdk.window.Window window [@property setter];

bool getBoundingBox(gdk.rectangle.Rectangle rect);

bool getBoundingBoxCenter(double x, double y);

gdk.device.Device getDevice();

gtk.gesture.Gesture[] getGroup();

gdk.event.Event getLastEvent(gdk.event_sequence.EventSequence sequence);

gdk.event_sequence.EventSequence getLastUpdatedSequence();

bool getPoint(gdk.event_sequence.EventSequence sequence, double x, double y);

gtk.types.EventSequenceState getSequenceState(gdk.event_sequence.EventSequence sequence);

gdk.event_sequence.EventSequence[] getSequences();

gdk.window.Window getWindow();

void group(gtk.gesture.Gesture gesture);

bool handlesSequence(gdk.event_sequence.EventSequence sequence);

bool isActive();

bool isGroupedWith(gtk.gesture.Gesture other);

bool isRecognized();

bool setSequenceState(gdk.event_sequence.EventSequence sequence, gtk.types.EventSequenceState state);

bool setState(gtk.types.EventSequenceState state);

void setWindow(gdk.window.Window window);

void ungroup();

gulong connectBegin(T callback, Flag!"After" after);

gulong connectCancel(T callback, Flag!"After" after);

gulong connectEnd(T callback, Flag!"After" after);

gulong connectSequenceStateChanged(T callback, Flag!"After" after);

gulong connectUpdate(T callback, Flag!"After" after);

}

Constructors

this this(void* ptr, Flag!"Take" take)

Members

Functions

connectBegin gulong connectBegin(T callback, Flag!"After" after): Connect to Begin signal.
connectCancel gulong connectCancel(T callback, Flag!"After" after): Connect to Cancel signal.
connectEnd gulong connectEnd(T callback, Flag!"After" after): Connect to End signal.
connectSequenceStateChanged gulong connectSequenceStateChanged(T callback, Flag!"After" after): Connect to SequenceStateChanged signal.
connectUpdate gulong connectUpdate(T callback, Flag!"After" after): Connect to Update signal.
getBoundingBox bool getBoundingBox(gdk.rectangle.Rectangle 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 gdk.device.Device getDevice(): Returns the master #GdkDevice that is currently operating on gesture, or null if the gesture is not being interacted.
getGroup gtk.gesture.Gesture[] getGroup(): Returns all gestures in the group of gesture
getLastEvent gdk.event.Event getLastEvent(gdk.event_sequence.EventSequence sequence): Returns the last event that was processed for sequence.
getLastUpdatedSequence gdk.event_sequence.EventSequence getLastUpdatedSequence(): Returns the #GdkEventSequence that was last updated on gesture.
getPoint bool getPoint(gdk.event_sequence.EventSequence 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 gtk.types.EventSequenceState getSequenceState(gdk.event_sequence.EventSequence sequence): Returns the sequence state, as seen by gesture.
getSequences gdk.event_sequence.EventSequence[] getSequences(): Returns the list of #GdkEventSequences currently being interpreted by gesture.
getWindow gdk.window.Window getWindow(): Returns the user-defined window that receives the events handled by gesture. See gtk.gesture.Gesture.setWindow for more information.
group void group(gtk.gesture.Gesture gesture): Adds gesture to the same group than group_gesture. Gestures are by default isolated in their own groups.
handlesSequence bool handlesSequence(gdk.event_sequence.EventSequence 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(gtk.gesture.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.
self Gesture self(): Returns this, for use in with statements.
setSequenceState bool setSequenceState(gdk.event_sequence.EventSequence sequence, gtk.types.EventSequenceState 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(gtk.types.EventSequenceState state): Sets the state of all sequences that gesture is currently interacting with. See gtk.gesture.Gesture.setSequenceState for more details on sequence states.
setWindow void setWindow(gdk.window.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.EventController.getWidget.
ungroup void ungroup(): Separates gesture into an isolated group.

Properties

_gType GType _gType [@property getter]
nPoints uint nPoints [@property getter]: Get nPoints property.
window gdk.window.Window window [@property getter]: Get window property.
window gdk.window.Window window [@property setter]: Set window property.

Static functions

_getGType GType _getGType()
builder GestureGidBuilder builder(): Get builder for gtk.gesture.Gesture

Inherited Members

From EventController

_getGType GType _getGType()
_gType GType _gType [@property getter]
self EventController self(): Returns this, for use in with statements.
builder EventControllerGidBuilder builder(): Get builder for gtk.event_controller.EventController
propagationPhase gtk.types.PropagationPhase propagationPhase [@property getter]: Get propagationPhase property.
propagationPhase gtk.types.PropagationPhase propagationPhase [@property setter]: Set propagationPhase property.
widget gtk.widget.Widget widget [@property getter]: Get widget property.
getPropagationPhase gtk.types.PropagationPhase getPropagationPhase(): Gets the propagation phase at which controller handles events.
getWidget gtk.widget.Widget getWidget(): Returns the #GtkWidget this controller relates to.
handleEvent bool handleEvent(gdk.event.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(gtk.types.PropagationPhase phase): Sets the propagation phase at which a controller handles events.

gtk gesture classes