c# winform richtextbox控制每行颜色 + 滚动条始终滚动到最底部

/// <summary>
/// 输出
/// </summary>
/// <param name="content"></param>
/// <param name="color"></param>
private void Output(string content, Color color)
{
Invoke(new MethodInvoker(delegate ()
{
//超出一万行，清空
this._lines++;
if (this._lines > )
{
this.txtOutput.Text = string.Empty;
this._lines = ;
} content += Environment.NewLine;
this.txtOutput.SelectionColor = color;//设置文本颜色
this.txtOutput.AppendText(content);//输出文本，换行 this.txtOutput.SelectionStart = this.txtOutput.Text.Length;//设置插入符位置为文本框末
this.txtOutput.ScrollToCaret();//滚动条滚到到最新插入行
}));
}