DragGestureRecognizer class

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.

See also:



DragGestureRecognizer({Object debugOwner, PointerDeviceKind kind, DragStartBehavior dragStartBehavior: DragStartBehavior.start })
Initialize the object. [...]


dragStartBehavior DragStartBehavior
Configure the behavior of offsets sent to onStart. [...]
read / write
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 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 and might begin to move. [...]
read / write
onEnd GestureDragEndCallback
A pointer that was previously in contact with the screen 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
onStart GestureDragStartCallback
A pointer has contacted the screen and has begun to move. [...]
read / write
onUpdate GestureDragUpdateCallback
A pointer that is in contact with the screen and moving has moved again. [...]
read / write
debugDescription String
Returns a very short pretty description of the gesture that the recognizer looks for, like 'tap' or 'horizontal drag'.
read-only, inherited
debugOwner Object
The recognizer's owner. [...]
final, inherited
hashCode int
The hash code for this object. [...]
read-only, inherited
runtimeType Type
A representation of the runtime type of the object.
read-only, inherited
team GestureArenaTeam
The team that this recognizer belongs to, if any. [...]
read / write, inherited


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


operator ==(dynamic other) bool
The equality operator. [...]