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 pointer is established, the recognizer calls onStart. As the focal point, scale, 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})
Create a gesture recognizer for interactions intended for scaling content.

Properties

debugDescription String
Returns a very short pretty description of the gesture that the recognizer looks for, like 'tap' or 'horizontal drag'.
read-only, override
debugOwner Object
The recognizer's owner. [...]
final, inherited
hashCode int
The hash code for this object. [...]
read-only, inherited
isFirstTap bool
read / write
isOnlyOnePoint bool
read / write
onDoubleTap GestureDoubleTapCallback
--------------------------DoubleTap-start-------------------------- Called when the user has tapped the screen at the same location twice in quick succession.
read / write
onEnd GestureScaleEndCallback
The pointers are no longer in contact with the screen.
read / write
onStart GestureScaleStartCallback
The pointers in contact with the screen have established a focal point and initial scale of 1.0.
read / write
onUpdate GestureScaleUpdateCallback
The pointers in contact with the screen have indicated a new focal point and/or scale.
read / write
pointCount int
read / write
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

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. [...]
@protected, inherited
addPointer(PointerEvent event) → void
Registers a new pointer that might be relevant to this gesture detector. [...]
override
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. [...]
@protected, 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
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
isWithinTolerance(PointerEvent event, double tolerance) bool
is two point within tolerance 双击 是否两个点在一个范围内
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent 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.
@mustCallSuper, @protected, inherited
resolvePointer(int pointer, GestureDisposition disposition) → void
Resolves this recognizer's participation in the given gesture arena with the given disposition.
@mustCallSuper, @protected, inherited
startDoubleTracking() → void
start track pointer 开始追踪双击手指
startTrackingPointer(int pointer, [Matrix4 transform]) → void
Causes events related to the given pointer ID to be routed to this recognizer. [...]
@protected, inherited
stopDoubleTracking() → void
stop track pointer 停止追踪双击手指
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. [...]
inherited
toString({DiagnosticLevel minLevel: DiagnosticLevel.info}) String
Returns 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 ==(dynamic other) bool
The equality operator. [...]
inherited