| // 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. |
| |
| // Template: dev/snippets/config/templates/stateful_widget_scaffold_center.tmpl |
| // |
| // Comment lines marked with "▼▼▼" and "▲▲▲" are used for authoring |
| // of samples, and may be ignored if you are just exploring the sample. |
| |
| // Flutter code sample for Listener |
| // |
| //*************************************************************************** |
| //* ▼▼▼▼▼▼▼▼ description ▼▼▼▼▼▼▼▼ (do not modify or remove section marker) |
| |
| // This example makes a [Container] react to being touched, showing a count of |
| // the number of pointer downs and ups. |
| |
| //* ▲▲▲▲▲▲▲▲ description ▲▲▲▲▲▲▲▲ (do not modify or remove section marker) |
| //*************************************************************************** |
| |
| import 'package:flutter/material.dart'; |
| //**************************************************************************** |
| //* ▼▼▼▼▼▼▼▼ code-imports ▼▼▼▼▼▼▼▼ (do not modify or remove section marker) |
| |
| import 'package:flutter/widgets.dart'; |
| |
| //* ▲▲▲▲▲▲▲▲ code-imports ▲▲▲▲▲▲▲▲ (do not modify or remove section marker) |
| //**************************************************************************** |
| |
| void main() => runApp(const MyApp()); |
| |
| /// This is the main application widget. |
| class MyApp extends StatelessWidget { |
| const MyApp({Key? key}) : super(key: key); |
| |
| static const String _title = 'Flutter Code Sample'; |
| |
| @override |
| Widget build(BuildContext context) { |
| return MaterialApp( |
| title: _title, |
| home: Scaffold( |
| appBar: AppBar(title: const Text(_title)), |
| body: const Center( |
| child: MyStatefulWidget(), |
| ), |
| ), |
| ); |
| } |
| } |
| |
| /// This is the stateful widget that the main application instantiates. |
| class MyStatefulWidget extends StatefulWidget { |
| const MyStatefulWidget({Key? key}) : super(key: key); |
| |
| @override |
| State<MyStatefulWidget> createState() => _MyStatefulWidgetState(); |
| } |
| |
| /// This is the private State class that goes with MyStatefulWidget. |
| class _MyStatefulWidgetState extends State<MyStatefulWidget> { |
| //******************************************************************** |
| //* ▼▼▼▼▼▼▼▼ code ▼▼▼▼▼▼▼▼ (do not modify or remove section marker) |
| |
| int _downCounter = 0; |
| int _upCounter = 0; |
| double x = 0.0; |
| double y = 0.0; |
| |
| void _incrementDown(PointerEvent details) { |
| _updateLocation(details); |
| setState(() { |
| _downCounter++; |
| }); |
| } |
| |
| void _incrementUp(PointerEvent details) { |
| _updateLocation(details); |
| setState(() { |
| _upCounter++; |
| }); |
| } |
| |
| void _updateLocation(PointerEvent details) { |
| setState(() { |
| x = details.position.dx; |
| y = details.position.dy; |
| }); |
| } |
| |
| @override |
| Widget build(BuildContext context) { |
| return ConstrainedBox( |
| constraints: BoxConstraints.tight(const Size(300.0, 200.0)), |
| child: Listener( |
| onPointerDown: _incrementDown, |
| onPointerMove: _updateLocation, |
| onPointerUp: _incrementUp, |
| child: Container( |
| color: Colors.lightBlueAccent, |
| child: Column( |
| mainAxisAlignment: MainAxisAlignment.center, |
| children: <Widget>[ |
| const Text( |
| 'You have pressed or released in this area this many times:'), |
| Text( |
| '$_downCounter presses\n$_upCounter releases', |
| style: Theme.of(context).textTheme.headline4, |
| ), |
| Text( |
| 'The cursor is here: (${x.toStringAsFixed(2)}, ${y.toStringAsFixed(2)})', |
| ), |
| ], |
| ), |
| ), |
| ), |
| ); |
| } |
| |
| //* ▲▲▲▲▲▲▲▲ code ▲▲▲▲▲▲▲▲ (do not modify or remove section marker) |
| //******************************************************************** |
| |
| } |