WPF RichTextBox 文本超过限定行数移除旧数据

在使用serilog.sinks.richtextbox 显示日志时，会需要移除旧的日志信息的需求，实现打码如下；

根据换行符“\n” 进行判断；

 

  private void CheckAndRemoveText()
  {
      int newLineCount = 0;
      bool removeText = false;

      foreach (Paragraph paragraph in _richTextBox.Document.Blocks)
      {
          foreach (Run run in paragraph.Inlines)
          {
              newLineCount += CountOccurrences(run.Text, "\n");

              if (newLineCount >= 3)
              {
                  removeText = true;
                  break;
              }
          }

          if (removeText)
          {
              RemoveTextBeforeFirstNewLine(paragraph);
              break;
          }
      }
  }

  private int CountOccurrences(string text, string pattern)
  {
      return text.Split(new string[] { pattern }, System.StringSplitOptions.None).Length - 1;
  }

  private void RemoveTextBeforeFirstNewLine(Paragraph paragraph)
  {
      string text = new TextRange(paragraph.ContentStart, paragraph.ContentEnd).Text;
      int index = text.IndexOf("\n");
      if (index != -1)
      {
          paragraph.Inlines.Clear();
          paragraph.Inlines.Add(new Run(text.Substring(index + 1)));
      }
  }