InheritedNotifier<T extends Listenable> class
abstract
An inherited widget for a Listenable notifier, which updates its dependencies when the notifier is triggered.
This is a variant of InheritedWidget, specialized for subclasses of Listenable, such as ChangeNotifier or ValueNotifier.
Dependents are notified whenever the notifier sends notifications, or whenever the identity of the notifier changes.
Multiple notifications are coalesced, so that dependents only rebuild once even if the notifier fires multiple times between two frames.
Typically this class is subclassed with a class that provides an of static
method that calls BuildContext.dependOnInheritedWidgetOfExactType with that
class.
The updateShouldNotify method may also be overridden, to change the logic in the cases where notifier itself is changed. The updateShouldNotify method is called with the old notifier in the case of the notifier being changed. When it returns true, the dependents are marked as needing to be rebuilt this frame.
SpinModel) to give them their
rotation. The InheritedNotifier doesn't need to know about the children,
and the notifier argument doesn't need to be an animation controller, it
can be anything that implements Listenable (like a ChangeNotifier).
The SpinModel class could just as easily listen to another object (say, a
separate object that keeps the value of an input or data model value) that
is a Listenable, and get the value from that. The descendants also don't
need to have an instance of the InheritedNotifier in order to use it, they
just need to know that there is one in their ancestry. This can help with
decoupling widgets from their models.
To create a local project with this code sample, run:
flutter create --sample=widgets.InheritedNotifier.1 mysample
See also:
- Animation, an implementation of Listenable that ticks each frame to update a value.
- ViewportOffset or its subclass ScrollPosition, implementations of Listenable that trigger when a view is scrolled.
- InheritedWidget, an inherited widget that only notifies dependents when its value is different.
- InheritedModel, an inherited widget that allows clients to subscribe to changes for subparts of the value.
- Inheritance
-
- Object
- DiagnosticableTree
- Widget
- ProxyWidget
- InheritedWidget
- InheritedNotifier
- Implementers
Constructors
- InheritedNotifier({Key? key, T? notifier, required Widget child})
-
Create an inherited widget that updates its dependents when notifier
sends notifications.
const
Properties
- child → Widget
-
The widget below this widget in the tree.
finalinherited
- hashCode → int
-
The hash code for this object.
no setterinherited
- key → Key?
-
Controls how one widget replaces another widget in the tree.
finalinherited
- notifier → T?
-
The Listenable object to which to listen.
final
- runtimeType → Type
-
A representation of the runtime type of the object.
no setterinherited
Methods
-
createElement(
) → InheritedElement -
Inflates this configuration to a concrete instance.
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
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a nonexistent method or property is accessed.
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 -
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 short, textual description of this widget.
inherited
-
updateShouldNotify(
covariant InheritedNotifier< T> oldWidget) → bool -
Whether the framework should notify widgets that inherit from this widget.
override
Operators
-
operator ==(
Object other) → bool -
The equality operator.
inherited