GestureBinding mixin Null safety

A binding for the gesture subsystem.

Lifecycle of pointer events and the gesture arena

PointerDownEvent

When a PointerDownEvent is received by the GestureBinding (from dart:ui.PlatformDispatcher.onPointerDataPacket, as interpreted by the PointerEventConverter), a hitTest is performed to determine which HitTestTarget nodes are affected. (Other bindings are expected to implement hitTest to defer to HitTestable objects. For example, the rendering layer defers to the RenderView and the rest of the render object hierarchy.)

The affected nodes then are given the event to handle (dispatchEvent calls HitTestTarget.handleEvent for each affected node). If any have relevant GestureRecognizers, they provide the event to them using GestureRecognizer.addPointer. This typically causes the recognizer to register with the PointerRouter to receive notifications regarding the pointer in question.

Once the hit test and dispatching logic is complete, the event is then passed to the aforementioned PointerRouter, which passes it to any objects that have registered interest in that event.

Finally, the gestureArena is closed for the given pointer (GestureArenaManager.close), which begins the process of selecting a gesture to win that pointer.

Other events

A pointer that is PointerEvent.down may send further events, such as PointerMoveEvent, PointerUpEvent, or PointerCancelEvent. These are sent to the same HitTestTarget nodes as were found when the PointerDownEvent was received (even if they have since been disposed; it is the responsibility of those objects to be aware of that possibility).

Then, the events are routed to any still-registered entrants in the PointerRouter's table for that pointer.

When a PointerUpEvent is received, the GestureArenaManager.sweep method is invoked to force the gesture arena logic to terminate if necessary.

Superclass Constraints

BindingBase

Implemented types

Mixin Applications

Properties

pointerRouter → PointerRouter: A router that routes all pointer events received from the engine.
final
gestureArena → GestureArenaManager: The gesture arenas used for disambiguating the meaning of sequences of pointer events.
final
pointerSignalResolver → PointerSignalResolver: The resolver used for determining which widget handles a PointerSignalEvent.
final
resamplingEnabled ↔ bool: Enable pointer event resampling for touch devices by setting this to true.
read / write
samplingOffset ↔ Duration: Offset relative to current frame time that should be used for resampling. The samplingOffset is expected to be negative. Non-negative samplingOffset is allowed but will effectively disable resampling.
read / write
debugSamplingClock → SamplingClock?: Overrides the sampling clock for debugging and testing.
protected">@protectedread-only
window → SingletonFlutterWindow: The main window to which this binding is bound.
read-onlyinherited
platformDispatcher → PlatformDispatcher: The ui.PlatformDispatcher to which this binding is bound.
read-onlyinherited
locked → bool: Whether lockEvents is currently locking events.
protected">@protectedread-onlyinherited
hashCode → int: The hash code for this object.
read-onlyinherited
runtimeType → Type: A representation of the runtime type of the object.
read-onlyinherited

Methods

cancelPointer(int pointer) → void: Dispatch a PointerCancelEvent for the given pointer soon.
dispatchEvent(PointerEvent event, HitTestResult? hitTestResult) → void: Dispatch an event to pointerRouter and the path of a hit test result.
override
handleEvent(PointerEvent event, HitTestEntry<HitTestTarget> entry) → void: Override this method to receive events.
override
handlePointerEvent(PointerEvent event) → void: Dispatch an event to the targets found by a hit test on its position.
hitTest(HitTestResult result, Offset position) → void: Determine which HitTestTarget objects are located at a given position.
override
initInstances() → void: The initialization method. Subclasses override this method to hook into the platform and otherwise configure their services. Subclasses must call "super.initInstances()".
override
initServiceExtensions() → void: Called when the binding is initialized, to register service extensions.
mustCallSuper">@mustCallSuperprotected">@protectedinherited
lockEvents(Future<void> callback()) → Future<void>: Locks the dispatching of asynchronous events and callbacks until the callback's future completes.
protected">@protectedinherited
noSuchMethod(Invocation invocation) → dynamic: Invoked when a non-existent method or property is accessed.
inherited
performReassemble() → Future<void>: This method is called by reassembleApplication to actually cause the application to reassemble, e.g. after a hot reload.
mustCallSuper">@mustCallSuperprotected">@protectedinherited
postEvent(String eventKind, Map<String, dynamic> eventData) → void: All events dispatched by a BindingBase use this method instead of calling developer.postEvent directly so that tests for BindingBase can track which events were dispatched by overriding this method.
protected">@protectedinherited
reassembleApplication() → Future<void>: Cause the entire application to redraw, e.g. after a hot reload.
inherited
registerBoolServiceExtension({required String name, required AsyncValueGetter<bool> getter, required AsyncValueSetter<bool> setter}) → void: Registers a service extension method with the given name (full name "ext.flutter.name"), which takes a single argument "enabled" which can have the value "true" or the value "false" or can be omitted to read the current value. (Any value other than "true" is considered equivalent to "false". Other arguments are ignored.)
protected">@protectedinherited
registerNumericServiceExtension({required String name, required AsyncValueGetter<double> getter, required AsyncValueSetter<double> setter}) → void: Registers a service extension method with the given name (full name "ext.flutter.name"), which takes a single argument with the same name as the method which, if present, must have a value that can be parsed by double.parse, and can be omitted to read the current value. (Other arguments are ignored.)
protected">@protectedinherited
registerServiceExtension({required String name, required ServiceExtensionCallback callback}) → void: Registers a service extension method with the given name (full name "ext.flutter.name").
protected">@protectedinherited
registerSignalServiceExtension({required String name, required AsyncCallback callback}) → void: Registers a service extension method with the given name (full name "ext.flutter.name"), which takes no arguments and returns no value.
protected">@protectedinherited
registerStringServiceExtension({required String name, required AsyncValueGetter<String> getter, required AsyncValueSetter<String> setter}) → void: Registers a service extension method with the given name (full name "ext.flutter.name"), which optionally takes a single argument with the name "value". If the argument is omitted, the value is to be read, otherwise it is to be set. Returns the current value.
protected">@protectedinherited
resetGestureBinding() → void: Reset states of GestureBinding.
protected">@protected
toString() → String: A string representation of this object.
inherited
unlocked() → void: Called by lockEvents when events get unlocked.
override

Operators

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

Static Properties

instance → GestureBinding: The singleton instance of this object.
read-only