value_listenable_provider.dart at f168a73 ⋅ rrousselGit/provider

import 'package:flutter/foundation.dart';
import 'package:flutter/widgets.dart';

import 'listenable_provider.dart' show ListenableProvider;
import 'provider.dart';

/// Listens to a [ValueListenable] and expose its current value.
class ValueListenableProvider<T>
    extends DeferredInheritedProvider<ValueListenable<T>, T> {
  /// Creates a [ValueNotifier] using [create] and automatically dispose it
  /// when [ValueListenableProvider] is removed from the tree.
  ///
  /// [create] must not be `null`.
  ///
  /// {@macro provider.updateshouldnotify}
  ///
  /// See also:
  ///
  ///   * [ValueListenable]
  ///   * [ListenableProvider], similar to [ValueListenableProvider] but for any
  /// kind of [Listenable].
  ValueListenableProvider({
    Key key,
    @required Create<ValueNotifier<T>> create,
    UpdateShouldNotify<T> updateShouldNotify,
    bool lazy,
    TransitionBuilder builder,
    Widget child,
  }) : super(
          key: key,
          create: create,
          lazy: lazy,
          builder: builder,
          updateShouldNotify: updateShouldNotify,
          startListening: _startListening(),
          dispose: _dispose,
          child: child,
        );

  /// Listens to [value] and exposes its current value.
  ///
  /// Changing [value] will stop listening to the previous [value] and listen
  /// the new one.  Removing [ValueListenableProvider] from the tree will also
  /// stop listening to [value].
  ///
  /// ```dart
  /// ValueListenable<int> foo;
  ///
  /// ValueListenableProvider<int>.value(
  ///   valueListenable: foo,
  ///   child: Container(),
  /// );
  /// ```
  ValueListenableProvider.value({
    Key key,
    @required ValueListenable<T> value,
    UpdateShouldNotify<T> updateShouldNotify,
    TransitionBuilder builder,
    Widget child,
  }) : super.value(
          key: key,
          builder: builder,
          value: value,
          updateShouldNotify: updateShouldNotify,
          startListening: _startListening(),
          child: child,
        );

  static void _dispose(BuildContext context, ValueListenable<Object> notifier) {
    if (notifier is ValueNotifier) {
      notifier.dispose();
    }
  }

  static DeferredStartListening<ValueListenable<T>, T> _startListening<T>() {
    return (_, setState, controller, __) {
      setState(controller.value);

      final listener = () => setState(controller.value);
      controller.addListener(listener);
      return () => controller.removeListener(listener);
    };
  }
}

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1		import 'package:flutter/foundation.dart';
2		import 'package:flutter/widgets.dart';
3
4		import 'listenable_provider.dart' show ListenableProvider;
5		import 'provider.dart';
6
7		/// Listens to a [ValueListenable] and expose its current value.
8		class ValueListenableProvider<T>
9		extends DeferredInheritedProvider<ValueListenable<T>, T> {
10		/// Creates a [ValueNotifier] using [create] and automatically dispose it
11		/// when [ValueListenableProvider] is removed from the tree.
12		///
13		/// [create] must not be `null`.
14		///
15		/// {@macro provider.updateshouldnotify}
16		///
17		/// See also:
18		///
19		/// * [ValueListenable]
20		/// * [ListenableProvider], similar to [ValueListenableProvider] but for any
21		/// kind of [Listenable].
22	3	ValueListenableProvider({
23		Key key,
24		@required Create<ValueNotifier<T>> create,
25		UpdateShouldNotify<T> updateShouldNotify,
26		bool lazy,
27		TransitionBuilder builder,
28		Widget child,
29	3	}) : super(
30		key: key,
31		create: create,
32		lazy: lazy,
33		builder: builder,
34		updateShouldNotify: updateShouldNotify,
35	3	startListening: _startListening(),
36		dispose: _dispose,
37		child: child,
38		);
39
40		/// Listens to [value] and exposes its current value.
41		///
42		/// Changing [value] will stop listening to the previous [value] and listen
43		/// the new one. Removing [ValueListenableProvider] from the tree will also
44		/// stop listening to [value].
45		///
46		/// ```dart
47		/// ValueListenable<int> foo;
48		///
49		/// ValueListenableProvider<int>.value(
50		/// valueListenable: foo,
51		/// child: Container(),
52		/// );
53		/// ```
54	3	ValueListenableProvider.value({
55		Key key,
56		@required ValueListenable<T> value,
57		UpdateShouldNotify<T> updateShouldNotify,
58		TransitionBuilder builder,
59		Widget child,
60	3	}) : super.value(
61		key: key,
62		builder: builder,
63		value: value,
64		updateShouldNotify: updateShouldNotify,
65	3	startListening: _startListening(),
66		child: child,
67		);
68
69	3	static void _dispose(BuildContext context, ValueListenable<Object> notifier) {
70	3	if (notifier is ValueNotifier) {
71	3	notifier.dispose();
72		}
73		}
74
75	3	static DeferredStartListening<ValueListenable<T>, T> _startListening<T>() {
76	3	return (_, setState, controller, __) {
77	3	setState(controller.value);
78
79	3	final listener = () => setState(controller.value);
80	3	controller.addListener(listener);
81	3	return () => controller.removeListener(listener);
82		};
83		}
84		}