How to use WebBrowser control DocumentCompleted event in C#?

Question

Before starting writing this question, i was trying to solve following

// 1. navigate to page
// 2. wait until page is downloaded
// 3. read and write some d         


        

Answer 1

Unlike Thorsten I didn't have to use ShDocVw, but what did make the difference for me was adding the loop checking ReadyState and using Application.DoEvents() while not ready. Here is my code:

        this.webBrowser.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(WebBrowser_DocumentCompleted);
        foreach (var item in this.urlList) // This is a Dictionary<string, string>
        {
            this.webBrowser.Navigate(item.Value);
            while (this.webBrowser1.ReadyState != WebBrowserReadyState.Complete)
            {
                Application.DoEvents();
            }
        }

And I used Yuki's solution for checking the results of WebBrowser_DocumentCompleted, though with the last if/else swapped per user's comment:

     private void WebBrowser_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
    {
        string url = e.Url.ToString();
        var browser = (WebBrowser)sender;

        if (!(url.StartsWith("http://") || url.StartsWith("https://")))     
        {             
            // in AJAX     
        }
        if (e.Url.AbsolutePath != this.webBrowser.Url.AbsolutePath)     
        {
            // IFRAME           
        }     
        else     
        {             
            // REAL DOCUMENT COMPLETE
            // Put my code here
        }
    }

Worked like a charm :)

Answer 2

I had to do something similar. What I do is use ShDocVw directly (adding a reference to all the necessary interop assemblies to my project). Then, I do not add the WebBrowser control to my form, but the AXShDocVw.AxWebBrowser control.

To navigate and wait I use to following method:

private void GotoUrlAndWait(AxWebBrowser wb, string url)
{
    object dummy = null;
    wb.Navigate(url, ref dummy, ref dummy, ref dummy, ref dummy);

    // Wait for the control the be initialized and ready.
    while (wb.ReadyState != SHDocVw.tagREADYSTATE.READYSTATE_COMPLETE)
        Application.DoEvents();
}

Answer 3

You might want to know the AJAX calls as well.

Consider using this:

private void webBrowser_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{
    string url = e.Url.ToString();
    if (!(url.StartsWith("http://") || url.StartsWith("https://")))
    {
            // in AJAX
    }

    if (e.Url.AbsolutePath != this.webBrowser.Url.AbsolutePath)
    {
            // IFRAME 
    }
    else
    {
            // REAL DOCUMENT COMPLETE
    }
}

Answer 4

Just thought to drop a line or two here about a small improvement which works in conjunction with the code of FeiBao. The idea is to inject a landmark (javascript) variable in the webpage and use that to detect which of the subsequent DocumentComplete events is the real deal. I doubt it's bulletproof but it has worked more reliably in general than the approach that lacks it. Any comments welcome. Here is the boilerplate code:

 void WebBrowser_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
    {
        string url = e.Url.ToString();
        var browser = (WebBrowser)sender;

        if (!(url.StartsWith("http://") || url.StartsWith("https://")))
        {
            // in AJAX     
        }
        if (e.Url.AbsolutePath != this.webBrowser.Url.AbsolutePath)
        {
            // IFRAME           
        }
        else if (browser.Document != null && (bool)browser.Document.InvokeScript("eval", new object[] { @"typeof window.YourLandMarkJavascriptVariableHere === 'undefined'" }))
        {
            ((IHTMLWindow2)browser.Document.Window.DomWindow).execScript("var window.YourLandMarkJavascriptVariableHere = true;");

            // REAL DOCUMENT COMPLETE
            // Put my code here
        }
    }

Answer 5

I have yet to find a working solution to this problem online. Hopefully this will make it to the top and save everyone the months of tweaking I spent trying to solve it, and the edge cases associated with it. I have fought over this issue over the years as Microsoft has changed the implementation/reliability of isBusy and document.readystate. With IE8, I had to resort to the following solution. It's similar to the question/answer from Margus with a few exceptions. My code will handle nested frames, javascript/ajax requests and meta-redirects. I have simplified the code for clarity sake, but I also use a timeout function (not included) to reset the webpage after if 5 minutes domAccess still equals false.

private void m_WebBrowser_BeforeNavigate(object pDisp, ref object URL, ref object Flags, ref object TargetFrameName, ref object PostData, ref object Headers, ref bool Cancel)
{
    //Javascript Events Trigger a Before Navigate Twice, but the first event 
    //will contain javascript: in the URL so we can ignore it.
    if (!URL.ToString().ToUpper().StartsWith("JAVASCRIPT:"))
    {
        //indicate the dom is not available
        this.domAccess = false;
        this.activeRequests.Add(URL);
    }
}

private void m_WebBrowser_DocumentComplete(object pDisp, ref object URL) 
{

    this.activeRequests.RemoveAt(0);

    //if pDisp Matches the main activex instance then we are done.
    if (pDisp.Equals((SHDocVw.WebBrowser)m_WebBrowser.ActiveXInstance)) 
    {
        //Top Window has finished rendering 
        //Since it will always render last, clear the active requests.
        //This solves Meta Redirects causing out of sync request counts
        this.activeRequests.Clear();
    }
    else if (m_WebBrowser.Document != null)
    {
        //Some iframe completed dom render
    }

    //Record the final complete URL for reference
    if (this.activeRequests.Count == 0)
    {
        //Finished downloading page - dom access ready
        this.domAccess = true;
    }
}