Detect WebBrowser complete page loading

Question

How can I detect when a System Windows Forms WebBrowser control has completed loading   I tried to use the Navigate and DocumentCompleted events but both of them were raised a few times during document loading

User · Answer

Using the DocumentCompleted event with a page with multiple nested frames didn't work for me.

I used the Interop.SHDocVW library to cast the WebBrowser control like this:

public class webControlWrapper
{
    private bool _complete;
    private WebBrowser _webBrowserControl;

    public webControlWrapper(WebBrowser webBrowserControl)
    {
        _webBrowserControl = webBrowserControl;
    }

    public void NavigateAndWaitForComplete(string url)
    {
        _complete = false;

        _webBrowserControl.Navigate(url);

        var webBrowser = (SHDocVw.WebBrowser) _webBrowserControl.ActiveXInstance;

        if (webBrowser != null)
            webBrowser.DocumentComplete += WebControl_DocumentComplete;

        //Wait until page is complete
        while (!_complete)
        {
            Application.DoEvents();
        }
    }

    private void WebControl_DocumentComplete(object pDisp, ref object URL)
    {
        // Test if it's the main frame who called the event.
        if (pDisp == _webBrowserControl.ActiveXInstance)
            _complete = true;
    }

This code works for me when navigating to a defined URL using the webBrowserControl.Navigate(url) method, but I don't know how to control page complete when a html button is clicked using the htmlElement.InvokeMember("click").

User · Answer

I did the following   void BrowserDocumentCompleted object sender          WebBrowserDocumentCompletedEventArgs e      if  e Url AbsolutePath     sender as WebBrowser  Url AbsolutePath      return        The page is finished loading      The last page loaded tends to be the one navigated to  so this should work   From here

User · Answer

Note the url in DocumentCompleted can be different than navigating url due to server transfer or url normalization  e g  you navigate to www microsoft com and got http   www microsoft com in documentcomplete   In pages with no frames  this event fires one time after loading is complete  In pages with multiple frames  this event fires for each navigating frame  note navigation is supported inside a frame  for instance clicking a link in a frame could navigate the frame to another page   The highest level navigating frame  which may or may not be the top level browser  fires the final DocumentComplete event    In native code you would compare the sender of the DocumentComplete event to determine if the event is the final event in the navigation or not  However in Windows Forms the sender parameter is not wrapped by WebBrowserDocumentCompletedEventArgs  You can either sink the native event to get the parameter s value  or check the readystate property of the browser or frame documents in the DocumentCompleted event handler to see if all frames are in the ready state   There is a prolblem with the readystate method as if a download manager is present and the navigation is to a downloadable file  the navigation could be cancelled by the download manager and the readystate won t become complete

User · Answer

It doesn t seem to trigger DocumentCompleted Navigated events for external Javascript or CSS files  but it will for iframes  As PK says  compare the WebBrowserDocumentCompletedEventArgs Url property  I don t have the karma to make a comment yet

User · Answer

I had the same issue of multiple DocumentCompleted fired events and tried out all the suggestions above  Finally  seems that in my case neither IsBusy property works right nor Url property  but the ReadyState seems to be what I needed  because it has the status  Interactive  while loading the multiple frames and it gets the status  Complete  only after loading the last one  Thus  I know when the page is fully loaded with all its components   I hope this may help others too

User · Answer

You can use the event ProgressChanged   the last time it is raised will indicate that the document is fully rendered   this webBrowser ProgressChanged    new WebBrowserProgressChangedEventHandler webBrowser ProgressChanged

User · Answer

I think the DocumentCompleted event will get fired for all child documents that are loaded as well  like JS and CSS  for example   You could look at the WebBrowserDocumentCompletedEventArgs in DocumentCompleted and check the Url property and compare that to the Url of the main page

User · Answer

The following should work   private void webBrowser1 DocumentCompleted object sender  WebBrowserDocumentCompletedEventArgs e          Check if page is fully loaded or not     if  this webBrowser1 ReadyState    WebBrowserReadyState Complete          return      else           Action to be taken on page loading completion

User · Answer

If you re using WPF there is a LoadCompleted event   If it s Windows Forms  the DocumentCompleted event should be the correct one  If the page you re loading has frames  your WebBrowser control will fire the DocumentCompleted event for each frame  see here for more details   I would suggest checking the IsBusy property each time the event is fired and if it is false then your page is fully done loading

[c#] Detect WebBrowser complete page loading

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