使用正则表达式限制TextBox输入

     /// <summary>
     ///  使用正则表达式限制输入
     /// </summary>
     public class TextBoxRegex : TextBox
     {
         // 正则表达式，只含有汉字、数字、字母、下划线不能以数字开头
         private const string NamimgPattern = "^(?![0-9])[a-zA-Z0-9_\u4e00-\u9fa5]{1,30}$";

         public TextBoxRegex()
         {
             TextChanged += TextBoxRegex_TextChanged;
         }

         private void TextBoxRegex_TextChanged(object sender, TextChangedEventArgs e)
         {
             //屏蔽非法字符粘贴
             var textBox = sender as TextBox;
             if (textBox != null)
             {
                 var change = new TextChange[e.Changes.Count];
                 e.Changes.CopyTo(change, );

                 int offset = change[].Offset;
                 if (change[].AddedLength > )
                 {
                     if (!Regex.IsMatch(textBox.Text, NamimgPattern, RegexOptions.IgnoreCase))
                     {
                         // 不符合正则表达式时移除内容，设置光标位置
                         textBox.Text = textBox.Text.Remove(offset, change[].AddedLength);
                         textBox.Select(offset, );
                     }
                 }
             }
         }
     }