61 lines
2.1 KiB
Dart
61 lines
2.1 KiB
Dart
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import 'package:flutter/widgets.dart';
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import 'package:imagini/bloc/bloc.dart';
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/// A Flutter widget which provides a bloc to its children via `BlocProvider.of(context)`.
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/// It is used as a DI widget so that a single instance of a bloc can be provided
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/// to multiple widgets within a subtree.
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class BlocProvider<T extends Bloc> extends InheritedWidget {
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/// The [Bloc] which is to be made available throughout the subtree
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final T bloc;
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/// The [Widget] and its descendants which will have access to the [Bloc].
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final Widget child;
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BlocProvider({
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Key key,
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@required this.bloc,
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this.child,
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}) : assert(bloc != null),
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super(key: key, child: child);
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/// Method that allows widgets to access the bloc as long as their `BuildContext`
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/// contains a `BlocProvider` instance.
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static T of<T extends Bloc>(BuildContext context) {
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final type = _typeOf<BlocProvider<T>>();
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final BlocProvider<T> provider = context
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.ancestorInheritedElementForWidgetOfExactType(type)
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?.widget as BlocProvider<T>;
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if (provider == null) {
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throw FlutterError(
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"""
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BlocProvider.of() called with a context that does not contain a Bloc of type $T.
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No ancestor could be found starting from the context that was passed to BlocProvider.of<$T>().
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This can happen if the context you use comes from a widget above the BlocProvider.
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This can also happen if you used BlocProviderTree and didn\'t explicity provide
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the BlocProvider types: BlocProvider(bloc: $T()) instead of BlocProvider<$T>(bloc: $T()).
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The context used was: $context
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""",
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);
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}
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return provider?.bloc;
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}
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/// Clone the current [BlocProvider] with a new child [Widget].
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/// All other values, including [Key] and [Bloc] are preserved.
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BlocProvider<T> copyWith(Widget child) {
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return BlocProvider<T>(
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key: key,
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bloc: bloc,
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child: child,
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);
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}
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/// Necessary to obtain generic [Type]
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/// https://github.com/dart-lang/sdk/issues/11923
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static Type _typeOf<T>() => T;
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@override
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bool updateShouldNotify(BlocProvider oldWidget) => false;
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}
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