m3_lightmeter/lib/utils/inherited_generics.dart

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2023-05-17 08:23:32 +00:00
import 'package:flutter/widgets.dart';
/// Listening to multiple dependencies at the same time causes firing an event for all dependencies
/// even though some of them didn't change:
/// ```dart
/// @override
/// void didChangeDependencies() {
/// super.didChangeDependencies();
/// _bloc.add(EquipmentProfileChangedEvent(EquipmentProfile.of(context)));
/// if (!MeteringScreenLayout.featureStatusOf(context, MeteringScreenLayoutFeature.filmPicker)) {
/// _bloc.add(const FilmChangedEvent(Film.other()));
/// }
/// }
/// ```
/// To overcome this issue I've decided to create a generic listener,
/// that will listen to each dependency separately.
class InheritedWidgetListener<T> extends StatefulWidget {
final ValueChanged<T> onDidChangeDependencies;
final Widget child;
const InheritedWidgetListener({
required this.onDidChangeDependencies,
required this.child,
super.key,
});
@override
State<InheritedWidgetListener<T>> createState() => _InheritedWidgetListenerState<T>();
}
class _InheritedWidgetListenerState<T> extends State<InheritedWidgetListener<T>> {
@override
void didChangeDependencies() {
super.didChangeDependencies();
widget.onDidChangeDependencies(context.listen<T>());
}
@override
Widget build(BuildContext context) {
return widget.child;
}
}
class InheritedWidgetBase<T> extends InheritedWidget {
final T data;
const InheritedWidgetBase({
required this.data,
required super.child,
super.key,
});
static T of<T>(BuildContext context, {bool listen = true}) {
if (listen) {
return context.dependOnInheritedWidgetOfExactType<InheritedWidgetBase<T>>()!.data;
} else {
return context.findAncestorWidgetOfExactType<InheritedWidgetBase<T>>()!.data;
}
}
@override
bool updateShouldNotify(InheritedWidgetBase<T> oldWidget) => true;
}
extension InheritedWidgetBaseContext on BuildContext {
T get<T>() {
return InheritedWidgetBase.of<T>(this, listen: false);
}
T listen<T>() {
return InheritedWidgetBase.of<T>(this);
}
}
/// Listening to multiple dependencies at the same time causes firing an event for all dependencies
/// even though some of them didn't change:
/// ```dart
/// @override
/// void didChangeDependencies() {
/// super.didChangeDependencies();
/// _bloc.add(EquipmentProfileChangedEvent(EquipmentProfile.of(context)));
/// if (!MeteringScreenLayout.featureStatusOf(context, MeteringScreenLayoutFeature.filmPicker)) {
/// _bloc.add(const FilmChangedEvent(Film.other()));
/// }
/// }
/// ```
/// To overcome this issue I've decided to create a generic listener,
/// that will listen to each dependency separately.
class InheritedModelAspectListener<A extends Object, T> extends StatefulWidget {
final A aspect;
final ValueChanged<T> onDidChangeDependencies;
final Widget child;
const InheritedModelAspectListener({
required this.aspect,
required this.onDidChangeDependencies,
required this.child,
super.key,
});
@override
State<InheritedModelAspectListener<A, T>> createState() =>
_InheritedModelAspectListenerState<A, T>();
}
class _InheritedModelAspectListenerState<A extends Object, T>
extends State<InheritedModelAspectListener<A, T>> {
@override
void didChangeDependencies() {
super.didChangeDependencies();
widget.onDidChangeDependencies(context.listenModelFeature<A, T>(widget.aspect));
}
@override
Widget build(BuildContext context) {
return widget.child;
}
}
class InheritedModelBase<A, T> extends InheritedModel<A> {
final Map<A, T> data;
const InheritedModelBase({
required this.data,
required super.child,
super.key,
});
static Map<A, T> of<A, T>(BuildContext context, {bool listen = true}) {
if (listen) {
return context.dependOnInheritedWidgetOfExactType<InheritedModelBase<A, T>>()!.data;
} else {
return context.findAncestorWidgetOfExactType<InheritedModelBase<A, T>>()!.data;
}
}
static T featureOf<A extends Object, T>(BuildContext context, A aspect) {
return InheritedModel.inheritFrom<InheritedModelBase<A, T>>(context, aspect: aspect)!
.data[aspect]!;
}
@override
bool updateShouldNotify(InheritedModelBase oldWidget) => true;
@override
bool updateShouldNotifyDependent(
InheritedModelBase<A, T> oldWidget,
Set<A> dependencies,
) {
for (final dependecy in dependencies) {
if (oldWidget.data[dependecy] != data[dependecy]) {
return true;
}
}
return false;
}
}
extension InheritedModelBaseContext on BuildContext {
Map<A, T> getModel<A, T>() {
return InheritedModelBase.of<A, T>(this, listen: false);
}
Map<A, T> listenModel<A, T>() {
return InheritedModelBase.of<A, T>(this);
}
T listenModelFeature<A extends Object, T>(A aspect) {
return InheritedModelBase.featureOf<A, T>(this, aspect);
}
}