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.

import 'package:flutter/material.dart';

/// Flutter code sample for [Switch].

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) {
    // This object sets amber as the track color when the switch is selected.
    // Otherwise, it resolves to null and defers to values from the theme data.
    const WidgetStateProperty<Color?> trackColor = WidgetStateProperty<Color?>.fromMap(
      <WidgetStatesConstraint, Color>{WidgetState.selected: Colors.amber},
    );
    // This object sets the track color based on two WidgetState attributes.
    // If neither state applies, it resolves to null.
    final WidgetStateProperty<Color?> overlayColor = WidgetStateProperty<Color?>.fromMap(
      <WidgetState, Color>{
        WidgetState.selected: Colors.amber.withOpacity(0.54),
        WidgetState.disabled: Colors.grey.shade400,
      },
    );

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