examples/api/lib/material/progress_indicator/circular_progress_indicator.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 [CircularProgressIndicator].

import 'package:flutter/material.dart';

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

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(useMaterial3: true, colorSchemeSeed: const Color(0xff6750a4)),
      home: const ProgressIndicatorExample(),
    );
  }
}

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

  @override
  State<ProgressIndicatorExample> createState() => _ProgressIndicatorExampleState();
}

class _ProgressIndicatorExampleState extends State<ProgressIndicatorExample>
    with TickerProviderStateMixin {
  late AnimationController controller;
  bool determinate = false;

  @override
  void initState() {
    controller = AnimationController(
      /// [AnimationController]s can be created with `vsync: this` because of
      /// [TickerProviderStateMixin].
      vsync: this,
      duration: const Duration(seconds: 2),
    )..addListener(() {
        setState(() {});
      });
    controller.repeat(reverse: true);
    super.initState();
  }

  @override
  void dispose() {
    controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Padding(
        padding: const EdgeInsets.all(20.0),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'Circular progress indicator',
              style: Theme.of(context).textTheme.titleLarge,
            ),
            const SizedBox(height: 30),
            CircularProgressIndicator(
              value: controller.value,
              semanticsLabel: 'Circular progress indicator',
            ),
            const SizedBox(height: 10),
            Row(
              children: <Widget>[
                Expanded(
                  child: Text(
                    'determinate Mode',
                    style: Theme.of(context).textTheme.titleSmall,
                  ),
                ),
                Switch(
                  value: determinate,
                  onChanged: (bool value) {
                    setState(() {
                      determinate = value;
                      if (determinate) {
                        controller.stop();
                      } else {
                        controller..forward(from: controller.value)..repeat();
                      }
                    });
                  },
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }
}