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Add the useOnListenableChange hook #390

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1 change: 1 addition & 0 deletions README.md
Original file line number Diff line number Diff line change
Expand Up @@ -333,6 +333,7 @@ They will take care of creating/updating/disposing an object.
| [useListenableSelector](https://pub.dev/documentation/flutter_hooks/latest/flutter_hooks/useListenableSelector.html) | Similar to `useListenable`, but allows filtering UI rebuilds |
| [useValueNotifier](https://pub.dev/documentation/flutter_hooks/latest/flutter_hooks/useValueNotifier.html) | Creates a `ValueNotifier` which will be automatically disposed. |
| [useValueListenable](https://pub.dev/documentation/flutter_hooks/latest/flutter_hooks/useValueListenable.html) | Subscribes to a `ValueListenable` and return its value. |
| [useOnListenableChange](https://pub.dev/documentation/flutter_hooks/latest/flutter_hooks/useOnListenableChange.html) | Subscribes to a `Listenable` and registers `listener` to the passed `listenable`. |

#### Misc hooks:

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58 changes: 58 additions & 0 deletions packages/flutter_hooks/lib/src/listenable.dart
Original file line number Diff line number Diff line change
Expand Up @@ -128,3 +128,61 @@ class _UseValueNotifierHookState<T>
@override
String get debugLabel => 'useValueNotifier';
}

/// Subscribes to a [Listenable] and registers `listener` to the passed `listenable`.
///
/// See also:
/// * [useListenable]
/// * [useEffect]
void useOnListenableChange(VoidCallback listener, Listenable listenable) {
use(_OnListenableChangeHook(listener, listenable));
}

class _OnListenableChangeHook extends Hook<void> {
_OnListenableChangeHook(this.listener, this.listenable)
: super(keys: [listenable]);
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final VoidCallback listener;
final Listenable listenable;

@override
_OnListenableChangeHookState createState() => _OnListenableChangeHookState();
}

class _OnListenableChangeHookState
extends HookState<void, _OnListenableChangeHook> {
Dispose? disposer;

@override
void initHook() {
super.initHook();
scheduleEffect();
}

@override
void didUpdateHook(_OnListenableChangeHook oldHook) {
super.didUpdateHook(oldHook);

if (hook.keys == null) {
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disposer?.call();
scheduleEffect();
}
}

@override
void build(BuildContext context) {}

@override
void dispose() => disposer?.call();

void scheduleEffect() {
hook.listenable.addListener(hook.listener);
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disposer = () => hook.listenable.removeListener(hook.listener);
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}

@override
String get debugLabel => 'useOnListenableChange';

@override
bool get debugSkipValue => true;
}
1 change: 1 addition & 0 deletions packages/flutter_hooks/test/use_on_listenable_change.dart
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
// TODO
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