examples/api/lib/material/context_menu/editable_text_toolbar_builder.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.

// This example demonstrates showing a custom context menu only when some
// narrowly defined text is selected.

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

const String emailAddress = 'me@example.com';
const String text = 'Select the email address and open the menu: $emailAddress';

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

  final TextEditingController _controller = TextEditingController(
    text: text,
  );

  void _showDialog (BuildContext context) {
    Navigator.of(context).push(
      DialogRoute<void>(
        context: context,
        builder: (BuildContext context) =>
          const AlertDialog(title: Text('You clicked send email!')),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Custom button for emails'),
        ),
        body: Center(
          child: Column(
            children: <Widget>[
              Container(height: 20.0),
              TextField(
                controller: _controller,
                contextMenuBuilder: (BuildContext context, EditableTextState editableTextState) {
                  final List<ContextMenuButtonItem> buttonItems =
                      editableTextState.contextMenuButtonItems;
                  // Here we add an "Email" button to the default TextField
                  // context menu for the current platform, but only if an email
                  // address is currently selected.
                  final TextEditingValue value = _controller.value;
                  if (_isValidEmail(value.selection.textInside(value.text))) {
                    buttonItems.insert(0, ContextMenuButtonItem(
                      label: 'Send email',
                      onPressed: () {
                        ContextMenuController.removeAny();
                        _showDialog(context);
                      },
                    ));
                  }
                  return AdaptiveTextSelectionToolbar.buttonItems(
                    anchors: editableTextState.contextMenuAnchors,
                    buttonItems: buttonItems,
                  );
                },
              ),
            ],
          ),
        ),
      ),
    );
  }
}

bool _isValidEmail(String text) {
  return RegExp(
    r'(?<name>[a-zA-Z0-9]+)'
    r'@'
    r'(?<domain>[a-zA-Z0-9]+)'
    r'\.'
    r'(?<topLevelDomain>[a-zA-Z0-9]+)',
  ).hasMatch(text);
}