C# webbrowser判断页面是否加载完毕

private void Form1_Load(object sender, EventArgs e)

        {

            webalipay.Url = new Uri("https://authzth.alipay.com/login/homeB.htm");

            webalipay.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(wb_DocumentCompleted);//加载完成后的事件

        }

        /// <summary>

        /// 页面加载完事件

        /// </summary>

        /// <param name="sender"></param>

        /// <param name="e"></param>

        private void wb_DocumentCompleted(object sender, EventArgs e)

        {

            //这个就是当网页载入完毕后要进行的操作

            hdoc = webalipay.Document;

            HtmlElement imgcode = Function.WebTools.GetElement_Id(hdoc, "J-checkcode-img");

            codeurl = imgcode.GetAttribute("src");

            piccode.Imagelocatio{过滤}n = codeurl;

        }