91 lines
2.0 KiB
Dart
91 lines
2.0 KiB
Dart
|
|
|
|
import 'package:flutter/cupertino.dart';
|
|
|
|
/// Event system
|
|
|
|
class ListenerReceipt<T> {
|
|
Function(T) listener;
|
|
|
|
ListenerReceipt(this.listener);
|
|
}
|
|
|
|
class EventDelegate<T> {
|
|
final List<ListenerReceipt<T>> _receipts = [];
|
|
|
|
ListenerReceipt<T> addListener(Function(T) listener) {
|
|
final receipt = ListenerReceipt(listener);
|
|
_receipts.add(receipt);
|
|
return receipt;
|
|
}
|
|
|
|
void removeListener(ListenerReceipt<T> receipt) {
|
|
_receipts.remove(receipt);
|
|
print("removed listener");
|
|
}
|
|
|
|
void trigger(T event) {
|
|
print("triggering event");
|
|
for (var receipt in _receipts) {
|
|
print("triggering listener");
|
|
try {
|
|
receipt.listener(event);
|
|
} catch (e) {
|
|
print("Error in listener: $e");
|
|
removeListener(receipt);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// flutter integration
|
|
|
|
class DelegateBuilder<T> extends StatefulWidget {
|
|
final EventDelegate<T> delegate;
|
|
final Widget Function(BuildContext, T) builder;
|
|
final Widget Function(BuildContext)? defaultBuilder;
|
|
|
|
DelegateBuilder({required this.delegate, required this.builder, this.defaultBuilder}) : super(key: UniqueKey())
|
|
{
|
|
print("created delegate builder widget");
|
|
}
|
|
|
|
@override
|
|
State<StatefulWidget> createState() => _DelegateBuilderState<T>();
|
|
|
|
|
|
}
|
|
|
|
class _DelegateBuilderState<T> extends State<DelegateBuilder<T>> {
|
|
late ListenerReceipt<T> _receipt;
|
|
|
|
T? lastEvent;
|
|
|
|
@override
|
|
void initState() {
|
|
super.initState();
|
|
print("init delegate builder widget");
|
|
_receipt = widget.delegate.addListener((event) {
|
|
lastEvent = event;
|
|
print("triggered");
|
|
setState(() {
|
|
|
|
});
|
|
});
|
|
|
|
}
|
|
|
|
@override
|
|
void dispose() {
|
|
super.dispose();
|
|
widget.delegate.removeListener(_receipt);
|
|
print("disposed");
|
|
}
|
|
|
|
@override
|
|
Widget build(BuildContext context) {
|
|
print("rebuilt");
|
|
print("Valid: ${lastEvent != null}");
|
|
return lastEvent == null ? widget.defaultBuilder == null ? Container() : widget.defaultBuilder!(context) : widget.builder(context, lastEvent!);
|
|
}
|
|
} |