WidgetStatesController class

Manages a set of WidgetStates and notifies listeners of changes.

Used by widgets that expose their internal state for the sake of extensions that add support for additional states. See TextButton for an example.

The controller's value is its current set of states. Listeners are notified whenever the value changes. The value should only be changed with update; it should not be modified directly.

The controller's value represents the set of states that a widget's visual properties, typically WidgetStateProperty values, are resolved against. It is not the intrinsic state of the widget. The widget is responsible for ensuring that the controller's value tracks its intrinsic state. For example one cannot request the keyboard focus for a widget by adding WidgetState.focused to its controller. When the widget gains the or loses the focus it will update its controller's value and notify listeners of the change.

When calling setState in a MaterialStatesController listener, use the SchedulerBinding.addPostFrameCallback to delay the call to setState after the frame has been rendered. It's generally prudent to use the SchedulerBinding.addPostFrameCallback because some of the widgets that depend on MaterialStatesController may call update in their build method. In such cases, listener's that call setState - during the build phase - will cause an error.

See also:



WidgetStatesController([Set<WidgetState>? value])
Creates a WidgetStatesController.


hashCode int
The hash code for this object.
no setterinherited
hasListeners bool
Whether any listeners are currently registered.
no setterinherited
runtimeType Type
A representation of the runtime type of the object.
no setterinherited
value Set<WidgetState>
The current value stored in this notifier.
getter/setter pairinherited


addListener(VoidCallback listener) → void
Register a closure to be called when the object changes.
dispose() → void
Discards any resources used by the object. After this is called, the object is not in a usable state and should be discarded (calls to addListener will throw after the object is disposed).
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
notifyListeners() → void
Call all the registered listeners.
removeListener(VoidCallback listener) → void
Remove a previously registered closure from the list of closures that are notified when the object changes.
toString() String
A string representation of this object.
update(WidgetState state, bool add) → void
Adds state to value if add is true, and removes it otherwise, and notifies listeners if value has changed.


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