| // 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. |
| |
| import 'dart:async'; |
| |
| import 'package:flutter/material.dart'; |
| |
| /// Flutter code sample for [StreamBuilder]. |
| |
| void main() => runApp(const StreamBuilderExampleApp()); |
| |
| class StreamBuilderExampleApp extends StatelessWidget { |
| const StreamBuilderExampleApp({super.key}); |
| |
| static const Duration delay = Duration(seconds: 1); |
| |
| @override |
| Widget build(BuildContext context) { |
| return const MaterialApp( |
| home: StreamBuilderExample(delay: delay), |
| ); |
| } |
| } |
| |
| class StreamBuilderExample extends StatefulWidget { |
| const StreamBuilderExample({ |
| required this.delay, |
| super.key, |
| }); |
| |
| final Duration delay; |
| |
| @override |
| State<StreamBuilderExample> createState() => _StreamBuilderExampleState(); |
| } |
| |
| class _StreamBuilderExampleState extends State<StreamBuilderExample> { |
| late final StreamController<int> _controller = StreamController<int>( |
| onListen: () async { |
| await Future<void>.delayed(widget.delay); |
| |
| if (!_controller.isClosed) { |
| _controller.add(1); |
| } |
| |
| await Future<void>.delayed(widget.delay); |
| |
| if (!_controller.isClosed) { |
| _controller.close(); |
| } |
| }, |
| ); |
| |
| Stream<int> get _bids => _controller.stream; |
| |
| @override |
| void dispose() { |
| if (!_controller.isClosed) { |
| _controller.close(); |
| } |
| super.dispose(); |
| } |
| |
| @override |
| Widget build(BuildContext context) { |
| return DefaultTextStyle( |
| style: Theme.of(context).textTheme.displayMedium!, |
| textAlign: TextAlign.center, |
| child: Container( |
| alignment: FractionalOffset.center, |
| color: Colors.white, |
| child: BidsStatus(bids: _bids), |
| ), |
| ); |
| } |
| } |
| |
| class BidsStatus extends StatelessWidget { |
| const BidsStatus({ |
| required this.bids, |
| super.key, |
| }); |
| |
| final Stream<int>? bids; |
| |
| @override |
| Widget build(BuildContext context) { |
| return 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: ${snapshot.stackTrace}', |
| maxLines: 1, |
| overflow: TextOverflow.ellipsis, |
| ), |
| ), |
| ]; |
| } else { |
| switch (snapshot.connectionState) { |
| case ConnectionState.none: |
| children = const <Widget>[ |
| Icon( |
| Icons.info, |
| color: Colors.blue, |
| size: 60, |
| ), |
| Padding( |
| padding: EdgeInsets.only(top: 16), |
| child: Text('Select a lot'), |
| ), |
| ]; |
| case ConnectionState.waiting: |
| children = const <Widget>[ |
| SizedBox( |
| width: 60, |
| height: 60, |
| child: CircularProgressIndicator(), |
| ), |
| Padding( |
| padding: EdgeInsets.only(top: 16), |
| child: Text('Awaiting bids...'), |
| ), |
| ]; |
| case ConnectionState.active: |
| children = <Widget>[ |
| const Icon( |
| Icons.check_circle_outline, |
| color: Colors.green, |
| size: 60, |
| ), |
| Padding( |
| padding: const EdgeInsets.only(top: 16), |
| child: Text('\$${snapshot.data}'), |
| ), |
| ]; |
| case ConnectionState.done: |
| children = <Widget>[ |
| const Icon( |
| Icons.info, |
| color: Colors.blue, |
| size: 60, |
| ), |
| Padding( |
| padding: const EdgeInsets.only(top: 16), |
| child: Text( |
| snapshot.hasData |
| ? '\$${snapshot.data} (closed)' |
| : '(closed)', |
| ), |
| ), |
| ]; |
| } |
| } |
| |
| return Column( |
| mainAxisAlignment: MainAxisAlignment.center, |
| children: children, |
| ); |
| }, |
| ); |
| } |
| } |