如何在flutter中删除选中的文本小工具？

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  final TextEditingController _controller = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Delete Selected Text'),
        ),
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              TextField(
                controller: _controller,
              ),
              RaisedButton(
                child: Text('Delete Selected Text'),
                onPressed: () {
                  final selection = _controller.selection;
                  if (selection.baseOffset == selection.extentOffset) {
                    // No text selected
                    return;
                  }
                  final text = _controller.text;
                  final newText = text.replaceRange(
                    selection.baseOffset,
                    selection.extentOffset,
                    '',
                  );
                  _controller.text = newText;
                },
              ),
            ],
          ),
        ),
      ),
    );
  }
}