ScaleGestureRecognizer class

Recognizes a scale gesture.

ScaleGestureRecognizer tracks the pointers in contact with the screen and calculates their focal point, indicated scale, and rotation. When a focal point is established, the recognizer calls onStart. As the focal point, scale, and rotation change, the recognizer calls onUpdate. When the pointers are no longer in contact with the screen, the recognizer calls onEnd.

Inheritance

Constructors

ScaleGestureRecognizer({Object? debugOwner, Set<PointerDeviceKind>? supportedDevices, AllowedButtonsFilter allowedButtonsFilter = _defaultButtonAcceptBehavior, DragStartBehavior dragStartBehavior = DragStartBehavior.down, bool trackpadScrollCausesScale = false, Offset trackpadScrollToScaleFactor = kDefaultTrackpadScrollToScaleFactor})
Create a gesture recognizer for interactions intended for scaling content.

Properties

allowedButtonsFilter → AllowedButtonsFilter
Called when interaction starts. This limits the dragging behavior for custom clicks (such as scroll click). Its parameter comes from PointerEvent.buttons.
finalinherited
debugDescription → String
Returns a very short pretty description of the gesture that the recognizer looks for, like 'tap' or 'horizontal drag'.
no setteroverride
debugOwner → Object?
The recognizer's owner.
finalinherited
dragStartBehavior ↔ DragStartBehavior
Determines what point is used as the starting point in all calculations involving this gesture.
getter/setter pair
gestureSettings ↔ DeviceGestureSettings?
Optional device specific configuration for device gestures that will take precedence over framework defaults.
getter/setter pairinherited
hashCode → int
The hash code for this object.
no setterinherited
onEnd ↔ GestureScaleEndCallback?
The pointers are no longer in contact with the screen.
getter/setter pair
onStart ↔ GestureScaleStartCallback?
The pointers in contact with the screen have established a focal point and initial scale of 1.0.
getter/setter pair
onUpdate ↔ GestureScaleUpdateCallback?
The pointers in contact with the screen have indicated a new focal point and/or scale.
getter/setter pair
pointerCount → int
The number of pointers being tracked by the gesture recognizer.
no setter
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
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.
getter/setter pairinherited
team ↔ GestureArenaTeam?
The team that this recognizer belongs to, if any.
getter/setter pairinherited
trackpadScrollCausesScale ↔ bool
Whether scrolling up/down on a trackpad should cause scaling instead of panning.
getter/setter pair
trackpadScrollToScaleFactor ↔ Offset
A factor to control the direction and magnitude of scale when converting trackpad scrolling.
getter/setter pair

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.
inherited
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
isPointerAllowed(PointerDownEvent event) → bool
Checks whether or not a pointer is allowed to be tracked by this recognizer.
inherited
isPointerPanZoomAllowed(PointerPanZoomStartEvent event) → bool
Checks whether or not a pointer pan/zoom is allowed to be tracked by this recognizer.
override
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, int wrapWidth = 65}) → 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