ToLaptop

lib/utils/delegates.dart

@@ -0,0 +1,90 @@
+
+
+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!);
+  }
+}