import 'package:flutter/material.dart'; Widget circleCheckBox() { return Container( child: Icon(Icons.check), ); } Size textSize(String text, TextStyle style) { final TextPainter textPainter = TextPainter( text: TextSpan(text: text, style: style), textDirection: TextDirection.ltr, )..layout(); // 布局文本 return textPainter.size; // 返回文本的尺寸 } bool isEmail(String email) { final emailRegex = RegExp(r'^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$'); return emailRegex.hasMatch(email); }