import 'dart:async'; import 'package:flutter/material.dart'; import 'matrix.dart'; class ConnectionStatusHeader extends StatefulWidget { @override _ConnectionStatusHeaderState createState() => _ConnectionStatusHeaderState(); } class _ConnectionStatusHeaderState extends State { StreamSubscription _onSyncSub; StreamSubscription _onSyncErrorSub; static bool _connected = true; set connected(bool connected) { if (mounted) { setState(() => _connected = connected); } } @override void dispose() { _onSyncSub?.cancel(); _onSyncErrorSub?.cancel(); super.dispose(); } @override Widget build(BuildContext context) { _onSyncSub ??= Matrix.of(context).client.onSync.stream.listen( (_) => connected = true, ); _onSyncErrorSub ??= Matrix.of(context).client.onSyncError.stream.listen( (_) => connected = false, ); return AnimatedContainer( duration: Duration(milliseconds: 500), height: _connected ? 0 : 5, child: LinearProgressIndicator(), ); } }