examples/api/lib/widgets/undo_history/undo_history_controller.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.

// Flutter code sample for UndoHistoryController.

import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

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

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      title: _title,
      home: MyHomePage(),
    );
  }
}

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

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  final TextEditingController _controller = TextEditingController();
  final FocusNode _focusNode = FocusNode();
  final UndoHistoryController _undoController = UndoHistoryController();

  TextStyle? get enabledStyle => Theme.of(context).textTheme.bodyMedium;
  TextStyle? get disabledStyle => Theme.of(context).textTheme.bodyMedium?.copyWith(color: Colors.grey);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            TextField(
              maxLines: 4,
              controller: _controller,
              focusNode: _focusNode,
              undoController: _undoController,
            ),
            ValueListenableBuilder<UndoHistoryValue>(
              valueListenable: _undoController,
              builder: (BuildContext context, UndoHistoryValue value, Widget? child) {
                return Row(
                  children: <Widget>[
                    TextButton(
                      child: Text('Undo', style: value.canUndo ? enabledStyle : disabledStyle),
                      onPressed: () {
                        _undoController.undo();
                      },
                    ),
                    TextButton(
                      child: Text('Redo', style: value.canRedo ? enabledStyle : disabledStyle),
                      onPressed: () {
                        _undoController.redo();
                      },
                    ),
                  ],
                );
              },
            ),
          ],
        ),
      ),
    );
  }
}