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// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// Flutter code sample for StreamBuilder
import 'dart:async';
import 'package:flutter/material.dart';
void main() => runApp(const MyApp());
class MyApp extends StatelessWidget {
const MyApp({super.key});
static const String _title = 'Flutter Code Sample';
@override
Widget build(BuildContext context) {
return const MaterialApp(
title: _title,
home: MyStatefulWidget(),
);
}
}
class MyStatefulWidget extends StatefulWidget {
const MyStatefulWidget({super.key});
@override
State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}
class _MyStatefulWidgetState extends State<MyStatefulWidget> {
final Stream<int> _bids = (() {
late final StreamController<int> controller;
controller = StreamController<int>(
onListen: () async {
await Future<void>.delayed(const Duration(seconds: 1));
controller.add(1);
await Future<void>.delayed(const Duration(seconds: 1));
await controller.close();
},
);
return controller.stream;
})();
@override
Widget build(BuildContext context) {
return DefaultTextStyle(
style: Theme.of(context).textTheme.headline2!,
textAlign: TextAlign.center,
child: Container(
alignment: FractionalOffset.center,
color: Colors.white,
child: StreamBuilder<int>(
stream: _bids,
builder: (BuildContext context, AsyncSnapshot<int> snapshot) {
List<Widget> children;
if (snapshot.hasError) {
children = <Widget>[
const Icon(
Icons.error_outline,
color: Colors.red,
size: 60,
),
Padding(
padding: const EdgeInsets.only(top: 16),
child: Text('Error: ${snapshot.error}'),
),
Padding(
padding: const EdgeInsets.only(top: 8),
child: Text('Stack trace: ${snapshot.stackTrace}'),
),
];
} else {
switch (snapshot.connectionState) {
case ConnectionState.none:
children = const <Widget>[
Icon(
Icons.info,
color: Colors.blue,
size: 60,
),
Padding(
padding: EdgeInsets.only(top: 16),
child: Text('Select a lot'),
),
];
break;
case ConnectionState.waiting:
children = const <Widget>[
SizedBox(
width: 60,
height: 60,
child: CircularProgressIndicator(),
),
Padding(
padding: EdgeInsets.only(top: 16),
child: Text('Awaiting bids...'),
),
];
break;
case ConnectionState.active:
children = <Widget>[
const Icon(
Icons.check_circle_outline,
color: Colors.green,
size: 60,
),
Padding(
padding: const EdgeInsets.only(top: 16),
child: Text('\$${snapshot.data}'),
),
];
break;
case ConnectionState.done:
children = <Widget>[
const Icon(
Icons.info,
color: Colors.blue,
size: 60,
),
Padding(
padding: const EdgeInsets.only(top: 16),
child: Text('\$${snapshot.data} (closed)'),
),
];
break;
}
}
return Column(
mainAxisAlignment: MainAxisAlignment.center,
children: children,
);
},
),
),
);
}
}