gi-gtk-3.0.36: Gtk bindings
CopyrightWill Thompson Iñaki García Etxebarria and Jonas Platte
LicenseLGPL-2.1
MaintainerIñaki García Etxebarria
Safe HaskellNone
LanguageHaskell2010

GI.Gtk.Objects.Gesture

Description

Gesture 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 Nothing EventSequence value for these).

The number of touches that a Gesture need to be recognized is controlled by the Gesture: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 Gesture::check signal regularly on input events until the gesture is recognized, the criteria to consider a gesture as "recognized" is left to Gesture 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 eventControllerSetPropagationPhase, or feed those manually through eventControllerHandleEvent.

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 buttonPressEvent, buttonReleaseEvent, touchEvent, etc signals. Gestures with the PropagationPhaseTarget 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.

# {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 gestureGroup, grouped gestures synchronize the state of sequences, so calling gestureSetSequenceState 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 gestureSetSequenceState to know about the possible lifetimes of a EventSequence.

Touchpad gestures

On the platforms that support it, Gesture will handle transparently touchpad gesture events. The only precautions users of Gesture should do to enable this support are:

Synopsis

Exported types

newtype Gesture Source #

Memory-managed wrapper type.

Constructors

Gesture (ManagedPtr Gesture) 

Instances

Instances details
Eq Gesture Source # 
Instance details

Defined in GI.Gtk.Objects.Gesture

Methods

(==) :: Gesture -> Gesture -> Bool #

(/=) :: Gesture -> Gesture -> Bool #

IsGValue Gesture Source #

Convert Gesture to and from GValue with toGValue and fromGValue.

Instance details

Defined in GI.Gtk.Objects.Gesture

ManagedPtrNewtype Gesture Source # 
Instance details

Defined in GI.Gtk.Objects.Gesture

TypedObject Gesture Source # 
Instance details

Defined in GI.Gtk.Objects.Gesture

Methods

glibType :: IO GType #

GObject Gesture Source # 
Instance details

Defined in GI.Gtk.Objects.Gesture

HasParentTypes Gesture Source # 
Instance details

Defined in GI.Gtk.Objects.Gesture

type ParentTypes Gesture Source # 
Instance details

Defined in GI.Gtk.Objects.Gesture

class (GObject o, IsDescendantOf Gesture o) => IsGesture o Source #

Type class for types which can be safely cast to Gesture, for instance with toGesture.

Instances

Instances details
(GObject o, IsDescendantOf Gesture o) => IsGesture o Source # 
Instance details

Defined in GI.Gtk.Objects.Gesture

toGesture :: (MonadIO m, IsGesture o) => o -> m Gesture Source #

Cast to Gesture, for types for which this is known to be safe. For general casts, use castTo.

Methods

Overloaded methods

getBoundingBox

gestureGetBoundingBox Source #

Arguments

:: (HasCallStack, MonadIO m, IsGesture a) 
=> a

gesture: a Gesture

-> m (Bool, Rectangle)

Returns: True if there are active touches, False otherwise

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.

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.

Since: 3.14

getBoundingBoxCenter

gestureGetBoundingBoxCenter Source #

Arguments

:: (HasCallStack, MonadIO m, IsGesture a) 
=> a

gesture: a Gesture

-> m (Bool, Double, Double)

Returns: False if no active touches are present, True otherwise

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.

Since: 3.14

getDevice

gestureGetDevice Source #

Arguments

:: (HasCallStack, MonadIO m, IsGesture a) 
=> a

gesture: a Gesture

-> m (Maybe Device)

Returns: a Device, or Nothing

Returns the master Device that is currently operating on gesture, or Nothing if the gesture is not being interacted.

Since: 3.14

getGroup

gestureGetGroup Source #

Arguments

:: (HasCallStack, MonadIO m, IsGesture a) 
=> a

gesture: a Gesture

-> m [Gesture]

Returns: The list of GtkGestures, free with g_list_free()

Returns all gestures in the group of gesture

Since: 3.14

getLastEvent

gestureGetLastEvent Source #

Arguments

:: (HasCallStack, MonadIO m, IsGesture a) 
=> a

gesture: a Gesture

-> Maybe EventSequence

sequence: a EventSequence

-> m (Maybe Event)

Returns: The last event from 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.

getLastUpdatedSequence

gestureGetLastUpdatedSequence Source #

Arguments

:: (HasCallStack, MonadIO m, IsGesture a) 
=> a

gesture: a Gesture

-> m (Maybe EventSequence)

Returns: The last updated sequence

Returns the EventSequence that was last updated on gesture.

Since: 3.14

getPoint

gestureGetPoint Source #

Arguments

:: (HasCallStack, MonadIO m, IsGesture a) 
=> a

gesture: a Gesture

-> Maybe EventSequence

sequence: a EventSequence, or Nothing for pointer events

-> m (Bool, Double, Double)

Returns: True if sequence is currently interpreted

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.

Since: 3.14

getSequenceState

gestureGetSequenceState Source #

Arguments

:: (HasCallStack, MonadIO m, IsGesture a) 
=> a

gesture: a Gesture

-> EventSequence

sequence: a EventSequence

-> m EventSequenceState

Returns: The sequence state in gesture

Returns the sequence state, as seen by gesture.

Since: 3.14

getSequences

gestureGetSequences Source #

Arguments

:: (HasCallStack, MonadIO m, IsGesture a) 
=> a

gesture: a Gesture

-> m [EventSequence]

Returns: A list of GdkEventSequences, the list elements are owned by GTK+ and must not be freed or modified, the list itself must be deleted through g_list_free()

Returns the list of GdkEventSequences currently being interpreted by gesture.

Since: 3.14

getWindow

gestureGetWindow Source #

Arguments

:: (HasCallStack, MonadIO m, IsGesture a) 
=> a

gesture: a Gesture

-> m (Maybe Window)

Returns: the user defined window, or Nothing if none

Returns the user-defined window that receives the events handled by gesture. See gestureSetWindow for more information.

Since: 3.14

group

gestureGroup Source #

Arguments

:: (HasCallStack, MonadIO m, IsGesture a, IsGesture b) 
=> a

groupGesture: Gesture to group gesture with

-> b

gesture: a Gesture

-> m () 

Adds gesture to the same group than groupGesture. Gestures are by default isolated in their own groups.

When gestures are grouped, the state of GdkEventSequences is kept in sync for all of those, so calling gestureSetSequenceState, on one will transfer the same value to the others.

Groups also perform an "implicit grabbing" of sequences, if a EventSequence state is set to GTK_EVENT_SEQUENCE_CLAIMED on one group, every other gesture group attached to the same Widget will switch the state for that sequence to GTK_EVENT_SEQUENCE_DENIED.

Since: 3.14

handlesSequence

gestureHandlesSequence Source #

Arguments

:: (HasCallStack, MonadIO m, IsGesture a) 
=> a

gesture: a Gesture

-> Maybe EventSequence

sequence: a EventSequence or Nothing

-> m Bool

Returns: True if gesture is handling sequence, False otherwise

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

Since: 3.14

isActive

gestureIsActive Source #

Arguments

:: (HasCallStack, MonadIO m, IsGesture a) 
=> a

gesture: a Gesture

-> m Bool

Returns: True if gesture is active

Returns True if the gesture is currently active. A gesture is active meanwhile there are touch sequences interacting with it.

Since: 3.14

isGroupedWith

gestureIsGroupedWith Source #

Arguments

:: (HasCallStack, MonadIO m, IsGesture a, IsGesture b) 
=> a

gesture: a Gesture

-> b

other: another Gesture

-> m Bool

Returns: whether the gestures are grouped

Returns True if both gestures pertain to the same group.

Since: 3.14

isRecognized

gestureIsRecognized Source #

Arguments

:: (HasCallStack, MonadIO m, IsGesture a) 
=> a

gesture: a Gesture

-> m Bool

Returns: True if gesture is recognized

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 Gesture::check returned True for the sequences being currently interpreted.

Since: 3.14

setSequenceState

gestureSetSequenceState Source #

Arguments

:: (HasCallStack, MonadIO m, IsGesture a) 
=> a

gesture: a Gesture

-> EventSequence

sequence: a EventSequence

-> EventSequenceState

state: the sequence state

-> m Bool

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

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:

  • 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 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:

static void
first_gesture_begin_cb (GtkGesture       *first_gesture,
                        GdkEventSequence *sequence,
                        gpointer          user_data)
{
  gtk_gesture_set_sequence_state (first_gesture, sequence, GTK_EVENT_SEQUENCE_CLAIMED);
  gtk_gesture_set_sequence_state (second_gesture, sequence, GTK_EVENT_SEQUENCE_DENIED);
}

static void
second_gesture_begin_cb (GtkGesture       *second_gesture,
                         GdkEventSequence *sequence,
                         gpointer          user_data)
{
  if (gtk_gesture_get_sequence_state (first_gesture, sequence) == GTK_EVENT_SEQUENCE_CLAIMED)
    gtk_gesture_set_sequence_state (second_gesture, sequence, GTK_EVENT_SEQUENCE_DENIED);
}

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.

Since: 3.14

setState

gestureSetState Source #

Arguments

:: (HasCallStack, MonadIO m, IsGesture a) 
=> a

gesture: a Gesture

-> EventSequenceState

state: the sequence state

-> m Bool

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

Sets the state of all sequences that gesture is currently interacting with. See gestureSetSequenceState for more details on sequence states.

Since: 3.14

setWindow

gestureSetWindow Source #

Arguments

:: (HasCallStack, MonadIO m, IsGesture a, IsWindow b) 
=> a

gesture: a Gesture

-> Maybe b

window: a Window, or Nothing

-> m () 

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 eventControllerGetWidget.

Since: 3.14

ungroup

gestureUngroup Source #

Arguments

:: (HasCallStack, MonadIO m, IsGesture a) 
=> a

gesture: a Gesture

-> m () 

Separates gesture into an isolated group.

Since: 3.14

Properties

nPoints

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

Since: 3.14

constructGestureNPoints :: (IsGesture o, MonadIO m) => Word32 -> m (GValueConstruct o) Source #

Construct a GValueConstruct with valid value for the “n-points” property. This is rarely needed directly, but it is used by new.

getGestureNPoints :: (MonadIO m, IsGesture o) => o -> m Word32 Source #

Get the value of the “n-points” property. When overloading is enabled, this is equivalent to

get gesture #nPoints

window

If non-Nothing, the gesture will only listen for events that happen on this Window, or a child of it.

Since: 3.14

clearGestureWindow :: (MonadIO m, IsGesture o) => o -> m () Source #

Set the value of the “window” property to Nothing. When overloading is enabled, this is equivalent to

clear #window

constructGestureWindow :: (IsGesture o, MonadIO m, IsWindow a) => a -> m (GValueConstruct o) Source #

Construct a GValueConstruct with valid value for the “window” property. This is rarely needed directly, but it is used by new.

getGestureWindow :: (MonadIO m, IsGesture o) => o -> m (Maybe Window) Source #

Get the value of the “window” property. When overloading is enabled, this is equivalent to

get gesture #window

setGestureWindow :: (MonadIO m, IsGesture o, IsWindow a) => o -> a -> m () Source #

Set the value of the “window” property. When overloading is enabled, this is equivalent to

set gesture [ #window := value ]

Signals

begin

type C_GestureBeginCallback = Ptr () -> Ptr EventSequence -> Ptr () -> IO () Source #

Type for the callback on the (unwrapped) C side.

type GestureBeginCallback Source #

Arguments

 = EventSequence

sequence: the EventSequence that made the gesture to be recognized

-> IO () 

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

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.

Since: 3.14

afterGestureBegin :: (IsGesture a, MonadIO m) => a -> GestureBeginCallback -> m SignalHandlerId Source #

Connect a signal handler for the begin signal, to be run after the default handler. When overloading is enabled, this is equivalent to

after gesture #begin callback

mk_GestureBeginCallback :: C_GestureBeginCallback -> IO (FunPtr C_GestureBeginCallback) Source #

Generate a function pointer callable from C code, from a C_GestureBeginCallback.

onGestureBegin :: (IsGesture a, MonadIO m) => a -> GestureBeginCallback -> m SignalHandlerId Source #

Connect a signal handler for the begin signal, to be run before the default handler. When overloading is enabled, this is equivalent to

on gesture #begin callback

cancel

type C_GestureCancelCallback = Ptr () -> Ptr EventSequence -> Ptr () -> IO () Source #

Type for the callback on the (unwrapped) C side.

type GestureCancelCallback Source #

Arguments

 = EventSequence

sequence: the EventSequence that was cancelled

-> IO () 

This signal is emitted whenever a sequence is cancelled. This usually happens on active touches when eventControllerReset is called on gesture (manually, due to grabs...), or the individual sequence was claimed by parent widgets' controllers (see gestureSetSequenceState).

gesture must forget everything about sequence as a reaction to this signal.

Since: 3.14

afterGestureCancel :: (IsGesture a, MonadIO m) => a -> GestureCancelCallback -> m SignalHandlerId Source #

Connect a signal handler for the cancel signal, to be run after the default handler. When overloading is enabled, this is equivalent to

after gesture #cancel callback

mk_GestureCancelCallback :: C_GestureCancelCallback -> IO (FunPtr C_GestureCancelCallback) Source #

Generate a function pointer callable from C code, from a C_GestureCancelCallback.

onGestureCancel :: (IsGesture a, MonadIO m) => a -> GestureCancelCallback -> m SignalHandlerId Source #

Connect a signal handler for the cancel signal, to be run before the default handler. When overloading is enabled, this is equivalent to

on gesture #cancel callback

end

type C_GestureEndCallback = Ptr () -> Ptr EventSequence -> Ptr () -> IO () Source #

Type for the callback on the (unwrapped) C side.

type GestureEndCallback Source #

Arguments

 = EventSequence

sequence: the EventSequence that made gesture recognition to finish

-> IO () 

This signal is emitted when gesture either stopped recognizing the event sequences as something to be handled (the Gesture::check handler returned False), or the number of touch sequences became higher or lower than Gesture: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 Gesture:n-points). This situation may be detected by checking through gestureHandlesSequence.

Since: 3.14

afterGestureEnd :: (IsGesture a, MonadIO m) => a -> GestureEndCallback -> m SignalHandlerId Source #

Connect a signal handler for the end signal, to be run after the default handler. When overloading is enabled, this is equivalent to

after gesture #end callback

mk_GestureEndCallback :: C_GestureEndCallback -> IO (FunPtr C_GestureEndCallback) Source #

Generate a function pointer callable from C code, from a C_GestureEndCallback.

onGestureEnd :: (IsGesture a, MonadIO m) => a -> GestureEndCallback -> m SignalHandlerId Source #

Connect a signal handler for the end signal, to be run before the default handler. When overloading is enabled, this is equivalent to

on gesture #end callback

sequenceStateChanged

type C_GestureSequenceStateChangedCallback = Ptr () -> Ptr EventSequence -> CUInt -> Ptr () -> IO () Source #

Type for the callback on the (unwrapped) C side.

type GestureSequenceStateChangedCallback Source #

Arguments

 = EventSequence

sequence: the EventSequence that was cancelled

-> EventSequenceState

state: the new sequence state

-> IO () 

This signal is emitted whenever a sequence state changes. See gestureSetSequenceState to know more about the expectable sequence lifetimes.

Since: 3.14

afterGestureSequenceStateChanged :: (IsGesture a, MonadIO m) => a -> GestureSequenceStateChangedCallback -> m SignalHandlerId Source #

Connect a signal handler for the sequenceStateChanged signal, to be run after the default handler. When overloading is enabled, this is equivalent to

after gesture #sequenceStateChanged callback

onGestureSequenceStateChanged :: (IsGesture a, MonadIO m) => a -> GestureSequenceStateChangedCallback -> m SignalHandlerId Source #

Connect a signal handler for the sequenceStateChanged signal, to be run before the default handler. When overloading is enabled, this is equivalent to

on gesture #sequenceStateChanged callback

update

type C_GestureUpdateCallback = Ptr () -> Ptr EventSequence -> Ptr () -> IO () Source #

Type for the callback on the (unwrapped) C side.

type GestureUpdateCallback Source #

Arguments

 = EventSequence

sequence: the EventSequence that was updated

-> IO () 

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.

Since: 3.14

afterGestureUpdate :: (IsGesture a, MonadIO m) => a -> GestureUpdateCallback -> m SignalHandlerId Source #

Connect a signal handler for the update signal, to be run after the default handler. When overloading is enabled, this is equivalent to

after gesture #update callback

mk_GestureUpdateCallback :: C_GestureUpdateCallback -> IO (FunPtr C_GestureUpdateCallback) Source #

Generate a function pointer callable from C code, from a C_GestureUpdateCallback.

onGestureUpdate :: (IsGesture a, MonadIO m) => a -> GestureUpdateCallback -> m SignalHandlerId Source #

Connect a signal handler for the update signal, to be run before the default handler. When overloading is enabled, this is equivalent to

on gesture #update callback