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Attach this Mixin to any State object will provide a built-in InheritedWidget
/// Any State object 'with' this mixin has then a built-in InheritedWidget
import 'package:flutter/material.dart';
mixin InheritedStateMixin<T extends StatefulWidget> on State<T> {
/// Traditionally called in the initState() function
void initInheritedState<U extends InheritedWidget>({
required U Function(Widget child) inheritedWidgetBuilder,
}) {
// Create the StatefulWidget to contain the InheritedWidget
_inheritedStatefulWidget = InheritedStatefulWidget<U>(
inheritedWidgetBuilder: inheritedWidgetBuilder,
child: _BuildBuilder(builder: buildChild));
/// Build the 'child' Widget passed to the InheritedWidget.
Widget buildChild(BuildContext context);
/// Provide access to the 'InheritedWidget' StatefulWidget
InheritedStatefulWidget get inheritedStatefulWidget =>
/// The Inherited StatefulWidget that contains the InheritedWidget.
late InheritedStatefulWidget _inheritedStatefulWidget;
/// Link a widget to a InheritedWidget of type U
bool widgetInherited(BuildContext? context) =>
InheritedElement? inheritedElement(BuildContext? context) =>
/// A flag to prevent infinite loops.
bool get buildInherited => _buildInherited;
bool _buildInherited = false;
/// Don't rebuild this State object but the State object containing the InheritedWidget.
/// Rebuild all the dependencies of the _InheritedWidget widget.
void setState(VoidCallback fn) {
_buildInherited = true;
_buildInherited = false;
/// Provide a means to rebuild this State object anyway.
void setStateSuper(VoidCallback fn) => super.setState(fn);
/// Implement this function instead of the build() function
/// to utilize a built-in FutureBuilder Widget and InheritedWidget.
/// Introduce an Inherited widget and simply passing through a 'child' widget.
/// When the Inherited Widget is rebuilt only this build() function is called.
/// i.e. The rest of the widget tree, widget.child, is left alone.
Widget build(BuildContext context) => _inheritedStatefulWidget;
/// Passes along a InheritedWidget to its State object.
class InheritedStatefulWidget<U extends InheritedWidget>
extends StatefulWidget {
/// No key so the state object is not rebuilt because it can't be.
Key? key,
required this.inheritedWidgetBuilder,
required this.child,
}) : state = _InheritedState(),
super(key: key);
/// Supply a child Widget to the returning InheritedWidget's child parameter.
final U Function(Widget child) inheritedWidgetBuilder;
/// The 'child' Widget eventually passed to the InheritedWidget.
final Widget child;
/// This StatefulWidget's State object.
final _InheritedState state;
//ignore: no_logic_in_create_state
_InheritedState createState() => state;
/// Link a widget to a InheritedWidget of type U
bool widgetInherited(BuildContext? context) {
bool dependOn = context != null;
if (dependOn) {
final inheritedWidget = context.dependOnInheritedWidgetOfExactType<U>();
dependOn = inheritedWidget != null;
return dependOn;
InheritedElement? inheritedElement(BuildContext? context) {
InheritedElement? element;
if (context != null) {
element = context.getElementForInheritedWidgetOfExactType<U>();
return element;
/// The 'child' widget passed to the InheritedWidget
Widget get inheritedChildWidget => state.child!;
/// set the child widget.
set inheritedChildWidget(Widget? child) => state.child = child;
/// Call its State object's setState() function
void setState(VoidCallback fn) => state._setState(fn);
/// Rebuild the InheritedWidget and its dependencies.
void buildInherited() => setState(() {});
/// In harmony with Flutter's own API
void notifyClients() => setState(() {});
/// Inline with 'older' frameworks
void refresh() => setState(() {});
class _InheritedState extends State<InheritedStatefulWidget> {
void initState() {
_widget = widget;
late InheritedStatefulWidget _widget;
/// Supply an alternate 'child' Widget
Widget? child;
/// Called by the StatefulWidget
void _setState(VoidCallback fn) => setState(fn);
Widget build(BuildContext context) =>
_widget.inheritedWidgetBuilder(child ??= _widget.child);
/// Creates a Widget but supplying contents to its build() function
class _BuildBuilder extends StatelessWidget {
const _BuildBuilder({Key? key, required this.builder}) : super(key: key);
final Widget Function(BuildContext context) builder;
Widget build(BuildContext context) {
late Widget widget;
try {
widget = builder(context);
} catch (e) {
final errorDetails = FlutterErrorDetails(
exception: e,
stack: e is Error ? e.stackTrace : null,
library: 'inherited_state_mixin.dart',
ErrorDescription("While building 'child' for InheritedWidget."),
widget = ErrorWidget.builder(errorDetails);
return widget;
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