如何创建在用户输入时更改字体和颜色的TextField？

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text('Dynamic TextField')),
        body: DynamicTextField(),
      ),
    );
  }
}

class DynamicTextField extends StatefulWidget {
  @override
  _DynamicTextFieldState createState() => _DynamicTextFieldState();
}

class _DynamicTextFieldState extends State<DynamicTextField> {
  String _text = '';
  Color _textColor = Colors.black;
  TextStyle _textStyle = TextStyle(fontSize: 16);

  void _updateText(String newText) {
    setState(() {
      _text = newText;
      // 根据输入内容动态更改颜色和字体
      if (newText.contains('red')) {
        _textColor = Colors.red;
        _textStyle = TextStyle(fontSize: 20, fontWeight: FontWeight.bold);
      } else if (newText.contains('blue')) {
        _textColor = Colors.blue;
        _textStyle = TextStyle(fontSize: 24, fontStyle: FontStyle.italic);
      } else {
        _textColor = Colors.black;
        _textStyle = TextStyle(fontSize: 16);
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return TextField(
      onChanged: _updateText,
      style: TextStyle(color: _textColor, fontSize: _textStyle.fontSize, fontStyle: _textStyle.fontStyle, fontWeight: _textStyle.fontWeight),
      decoration: InputDecoration(
        hintText: 'Enter text here',
        border: OutlineInputBorder(),
      ),
    );
  }
}