DragGestureRecognizer class abstract

Recognizes movement.

In contrast to MultiDragGestureRecognizer, DragGestureRecognizer recognizes a single gesture sequence for all the pointers it watches, which means that the recognizer has at most one drag sequence active at any given time regardless of how many pointers are in contact with the screen.

DragGestureRecognizer is not intended to be used directly. Instead, consider using one of its subclasses to recognize specific types for drag gestures.

DragGestureRecognizer competes on pointer events only when it has at least one non-null callback. If it has no callbacks, it is a no-op.

Constructors

DragGestureRecognizer({Object? debugOwner, DragStartBehavior dragStartBehavior = DragStartBehavior.start, GestureVelocityTrackerBuilder velocityTrackerBuilder = _defaultBuilder, bool onlyAcceptDragOnThreshold = false, Set<PointerDeviceKind>? supportedDevices, AllowedButtonsFilter? allowedButtonsFilter}): Initialize the object.

Properties

debugDescription → String: Returns a very short pretty description of the gesture that the recognizer looks for, like 'tap' or 'horizontal drag'.
read-onlyinherited
debugLastPendingEventTimestamp → Duration?: When asserts are enabled, returns the last tracked pending event timestamp for this recognizer.
read-only
debugOwner → Object?: The recognizer's owner.
finalinherited
dragStartBehavior ↔ DragStartBehavior: Configure the behavior of offsets passed to onStart.
read / write
gestureSettings ↔ DeviceGestureSettings?: Optional device specific configuration for device gestures that will take precedence over framework defaults.
read / writeinherited
hashCode → int: The hash code for this object.
read-onlyinherited
maxFlingVelocity ↔ double?: Fling velocity magnitudes will be clamped to this value.
read / write
minFlingDistance ↔ double?: The minimum distance an input pointer drag must have moved to be considered a fling gesture.
read / write
minFlingVelocity ↔ double?: The minimum velocity for an input pointer drag to be considered fling.
read / write
onCancel ↔ GestureDragCancelCallback?: The pointer that previously triggered onDown did not complete.
read / write
onDown ↔ GestureDragDownCallback?: A pointer has contacted the screen with a primary button and might begin to move.
read / write
onEnd ↔ GestureDragEndCallback?: A pointer that was previously in contact with the screen with a primary button and moving is no longer in contact with the screen and was moving at a specific velocity when it stopped contacting the screen.
read / write
onlyAcceptDragOnThreshold ↔ bool: Whether the drag threshold should be met before dispatching any drag callbacks.
read / write
onStart ↔ GestureDragStartCallback?: A pointer has contacted the screen with a primary button and has begun to move.
read / write
onUpdate ↔ GestureDragUpdateCallback?: A pointer that is in contact with the screen with a primary button and moving has moved again.
read / write
runtimeType → Type: A representation of the runtime type of the object.
read-onlyinherited
supportedDevices ↔ Set<PointerDeviceKind>?: The kind of devices that are allowed to be recognized as provided by supportedDevices in the constructor, or the currently deprecated kind. These cannot both be set. If both are null, events from all device kinds will be tracked and recognized.
read / writeinherited
team ↔ GestureArenaTeam?: The team that this recognizer belongs to, if any.
read / writeinherited
velocityTrackerBuilder ↔ GestureVelocityTrackerBuilder: Determines the type of velocity estimation method to use for a potential drag gesture, when a new pointer is added.
read / write

Methods

acceptGesture(int pointer) → void: Called when this member wins the arena for the given pointer id.
override
addAllowedPointer(PointerDownEvent event) → void: Registers a new pointer that's been checked to be allowed by this gesture recognizer.
override
addAllowedPointerPanZoom(PointerPanZoomStartEvent event) → void: Registers a new pointer pan/zoom that's been checked to be allowed by this gesture recognizer.
override
addPointer(PointerDownEvent event) → void: Registers a new pointer that might be relevant to this gesture detector.
inherited
addPointerPanZoom(PointerPanZoomStartEvent event) → void: Registers a new pointer pan/zoom that might be relevant to this gesture detector.
inherited
debugDescribeChildren() → List<DiagnosticsNode>: Returns a list of DiagnosticsNode objects describing this node's children.
inherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void: Add additional properties associated with the node.
override
didStopTrackingLastPointer(int pointer) → void: Called when the number of pointers this recognizer is tracking changes from one to zero.
override
dispose() → void: Releases any resources used by the object.
override
getKindForPointer(int pointer) → PointerDeviceKind: For a given pointer ID, returns the device kind associated with it.
inherited
handleEvent(PointerEvent event) → void: Called when a pointer event is routed to this recognizer.
override
handleNonAllowedPointer(PointerDownEvent event) → void: Handles a pointer being added that's not allowed by this recognizer.
inherited
handleNonAllowedPointerPanZoom(PointerPanZoomStartEvent event) → void: Handles a pointer pan/zoom being added that's not allowed by this recognizer.
inherited
invokeCallback<T>(String name, RecognizerCallback<T> callback, {String debugReport()?}) → T?: Invoke a callback provided by the application, catching and logging any exceptions.
inherited
isFlingGesture(VelocityEstimate estimate, PointerDeviceKind kind) → bool: Determines if a gesture is a fling or not based on velocity.
isPointerAllowed(PointerEvent event) → bool: Checks whether or not a pointer is allowed to be tracked by this recognizer.
override
isPointerPanZoomAllowed(PointerPanZoomStartEvent event) → bool: Checks whether or not a pointer pan/zoom is allowed to be tracked by this recognizer.
inherited
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
rejectGesture(int pointer) → void: Called when this member loses the arena for the given pointer id.
override
resolve(GestureDisposition disposition) → void: Resolves this recognizer's participation in each gesture arena with the given disposition.
inherited
resolvePointer(int pointer, GestureDisposition disposition) → void: Resolves this recognizer's participation in the given gesture arena with the given disposition.
inherited
startTrackingPointer(int pointer, [Matrix4? transform]) → void: Causes events related to the given pointer ID to be routed to this recognizer.
inherited
stopTrackingIfPointerNoLongerDown(PointerEvent event) → void: Stops tracking the pointer associated with the given event if the event is a PointerUpEvent or a PointerCancelEvent event.
inherited
stopTrackingPointer(int pointer) → void: Stops events related to the given pointer ID from being routed to this recognizer.
inherited
toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) → DiagnosticsNode: Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.
inherited
toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) → String: A string representation of this object.
inherited
toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String: Returns a string representation of this node and its descendants.
inherited
toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String: Returns a one-line detailed description of the object.
inherited
toStringShort() → String: A brief description of this object, usually just the runtimeType and the hashCode.
inherited

Operators

operator ==(Object other) → bool: The equality operator.
inherited