SemanticsBinding mixin

The glue between the semantics layer and the Flutter engine.

Superclass Constraints
Mixin Applications


semanticsEnabled bool
Whether semantics information must be collected.
no setter
debugOutstandingSemanticsHandles int
The number of clients registered to listen for semantics.
no setter
accessibilityFeatures AccessibilityFeatures
The currently active set of AccessibilityFeatures.
no setter
disableAnimations bool
The platform is requesting that animations be disabled or simplified.
no setter
window SingletonFlutterWindow
Deprecated. Will be removed in a future version of Flutter.
no setterinherited
platformDispatcher PlatformDispatcher
The ui.PlatformDispatcher to which this binding is bound.
no setterinherited
locked bool
Whether lockEvents is currently locking events.
no setterinherited
hashCode int
The hash code for this object.
no setterinherited
runtimeType Type
A representation of the runtime type of the object.
no setterinherited


addSemanticsEnabledListener(VoidCallback listener) → void
Adds a listener to be called when semanticsEnabled changes.
createSemanticsUpdateBuilder() SemanticsUpdateBuilder
Creates an empty semantics update builder.
debugCheckZone(String entryPoint) bool
Checks that the current Zone is the same as that which was used to initialize the binding.
ensureSemantics() SemanticsHandle
Creates a new SemanticsHandle and requests the collection of semantics information.
handleAccessibilityFeaturesChanged() → void
Called when the platform accessibility features change.
initInstances() → void
The initialization method. Subclasses override this method to hook into the platform and otherwise configure their services. Subclasses must call "super.initInstances()".
initServiceExtensions() → void
Called when the binding is initialized, to register service extensions.
lockEvents(Future<void> callback()) Future<void>
Locks the dispatching of asynchronous events and callbacks until the callback's future completes.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
performReassemble() Future<void>
This method is called by reassembleApplication to actually cause the application to reassemble, e.g. after a hot reload.
performSemanticsAction(SemanticsActionEvent action) → void
Called whenever the platform requests an action to be performed on a SemanticsNode.
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.
reassembleApplication() Future<void>
Cause the entire application to redraw, e.g. after a hot reload.
registerBoolServiceExtension({required String name, required AsyncValueGetter<bool> getter, required AsyncValueSetter<bool> setter}) → void
Registers a service extension method with the given name (full 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.)
registerNumericServiceExtension({required String name, required AsyncValueGetter<double> getter, required AsyncValueSetter<double> setter}) → void
Registers a service extension method with the given name (full 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.)
registerServiceExtension({required String name, required ServiceExtensionCallback callback}) → void
Registers a service extension method with the given name (full name "").
registerSignalServiceExtension({required String name, required AsyncCallback callback}) → void
Registers a service extension method with the given name (full name ""), which takes no arguments and returns no value.
registerStringServiceExtension({required String name, required AsyncValueGetter<String> getter, required AsyncValueSetter<String> setter}) → void
Registers a service extension method with the given name (full 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.
removeSemanticsEnabledListener(VoidCallback listener) → void
Removes a listener added by addSemanticsEnabledListener.
toString() String
A string representation of this object.
unlocked() → void
Called by lockEvents when events get unlocked.


operator ==(Object other) bool
The equality operator.

Static Properties

instance SemanticsBinding
The current SemanticsBinding, if one has been created.
no setter