examples/api/lib/widgets/basic/listener.0.dart

// 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 'package:flutter/material.dart';

/// Flutter code sample for [Listener].

void main() => runApp(const ListenerApp());

class ListenerApp extends StatelessWidget {
  const ListenerApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: const Text('Listener Sample')),
        body: const Center(
          child: ListenerExample(),
        ),
      ),
    );
  }
}

class ListenerExample extends StatefulWidget {
  const ListenerExample({super.key});

  @override
  State<ListenerExample> createState() => _ListenerExampleState();
}

class _ListenerExampleState extends State<ListenerExample> {
  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: ColoredBox(
          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.headlineMedium,
              ),
              Text(
                'The cursor is here: (${x.toStringAsFixed(2)}, ${y.toStringAsFixed(2)})',
              ),
            ],
          ),
        ),
      ),
    );
  }
}