UndoHistoryController class
A controller for the undo history, for example for an editable text field.
Whenever a change happens to the underlying value that the UndoHistory widget tracks, that widget updates the value and the controller notifies it's listeners. Listeners can then read the canUndo and canRedo properties of the value to discover whether undo or redo are possible.
The controller also has undo and redo methods to modify the undo history.
This example creates a TextField with an UndoHistoryController
which provides undo and redo buttons.
link
To create a local project with this code sample, run:
flutter create --sample=widgets.UndoHistoryController.1 mysample
See also:
- EditableText, which uses the UndoHistory widget and allows control of the underlying history using an UndoHistoryController.
- Inheritance
-
- Object
- ChangeNotifier
- ValueNotifier<
UndoHistoryValue> - UndoHistoryController
Constructors
- UndoHistoryController({UndoHistoryValue? value})
- Creates a controller for an UndoHistory widget.
Properties
- hashCode → int
-
The hash code for this object.
no setterinherited
- hasListeners → bool
-
Whether any listeners are currently registered.
no setterinherited
- onRedo → ChangeNotifier
-
Notifies listeners that redo has been called.
final
- onUndo → ChangeNotifier
-
Notifies listeners that undo has been called.
final
- runtimeType → Type
-
A representation of the runtime type of the object.
no setterinherited
- value ↔ UndoHistoryValue
-
The current value stored in this notifier.
getter/setter pairinherited
Methods
-
addListener(
VoidCallback listener) → void -
Register a closure to be called when the object changes.
inherited
-
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).
override
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a nonexistent method or property is accessed.
inherited
-
notifyListeners(
) → void -
Call all the registered listeners.
inherited
-
redo(
) → void - Updates the value on the stack to the next value.
-
removeListener(
VoidCallback listener) → void -
Remove a previously registered closure from the list of closures that are
notified when the object changes.
inherited
-
toString(
) → String -
A string representation of this object.
inherited
-
undo(
) → void - Reverts the value on the stack to the previous value.
Operators
-
operator ==(
Object other) → bool -
The equality operator.
inherited