flutter/examples/api/lib/material/switch/switch.1.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.

/// Flutter code sample for [Switch].

import 'package:flutter/material.dart';

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

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

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

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

  @override
  State<SwitchExample> createState() => _SwitchExampleState();
}

class _SwitchExampleState extends State<SwitchExample> {
  bool light = true;

  @override
  Widget build(BuildContext context) {
    final MaterialStateProperty<Color?> trackColor = MaterialStateProperty.resolveWith<Color?>(
      (Set<MaterialState> states) {
        // Track color when the switch is selected.
        if (states.contains(MaterialState.selected)) {
          return Colors.amber;
        }
        // Otherwise return null to set default track color
        // for remaining states such as when the switch is
        // hovered, focused, or disabled.
        return null;
      },
    );
    final MaterialStateProperty<Color?> overlayColor = MaterialStateProperty.resolveWith<Color?>(
      (Set<MaterialState> states) {
        // Material color when switch is selected.
        if (states.contains(MaterialState.selected)) {
          return Colors.amber.withOpacity(0.54);
        }
        // Material color when switch is disabled.
        if (states.contains(MaterialState.disabled)) {
          return Colors.grey.shade400;
        }
        // Otherwise return null to set default material color
        // for remaining states such as when the switch is
        // hovered, or focused.
        return null;
      },
    );

    return Switch(
      // This bool value toggles the switch.
      value: light,
      overlayColor: overlayColor,
      trackColor: trackColor,
      thumbColor: const MaterialStatePropertyAll<Color>(Colors.black),
      onChanged: (bool value) {
        // This is called when the user toggles the switch.
        setState(() {
          light = value;
        });
      },
    );
  }
}