How to detect if dynamic web page in WebBrowser redraws?

In the WebBrowser control in C#, there is no built-in event specifically designed to detect when a dynamic web page redraws. However, you can use a combination of existing events and techniques to achieve a similar effect. Here's an approach you can take:

1. Attach an event handler to the DocumentCompleted event of the WebBrowser control. This event is fired when the web page finishes loading.

2. Inside the DocumentCompleted event handler, you can use JavaScript injection to detect changes on the web page. Execute JavaScript code that sets up an observer to monitor the DOM changes and triggers a custom event when changes occur.

   Here's an example of how you can inject JavaScript code to monitor DOM changes using the DocumentCompleted event handler:

   csharpCopy code
   private void webBrowser1_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
   
   {
   
       // Inject JavaScript code to monitor DOM changes
   
       webBrowser1.Document.InvokeScript(@"
   
           (function() {
   
               var observer = new MutationObserver(function() {
   
                   // Trigger a custom event when DOM changes occur
   
                   var event = new CustomEvent('pageRedraw');
   
                   document.dispatchEvent(event);
   
               });
   
   
   
               observer.observe(document, { childList: true, subtree: true });
   
           })();
   
       ");
   
   }
   
   

3. Next, you can attach another event handler to the Document's DomEvent event and listen for the custom event you triggered in the injected JavaScript code.

   csharpCopy code
   private void webBrowser1_Document_DomEvent(object sender, HtmlElementEventArgs e)
   
   {
   
       // Check if the custom event 'pageRedraw' was triggered
   
       if (e.EventType == "pageRedraw")
   
       {
   
           // Handle the redraw event here
   
           Console.WriteLine("Web page redraw detected");
   
       }
   
   }
   
   

By combining the DocumentCompleted event, JavaScript injection, and the Document's DomEvent event, you can detect and respond to dynamic web page redraws in the WebBrowser control.

Note that the accuracy and effectiveness of this approach may depend on the specific web page and its behavior. Some dynamic web pages may have complex rendering mechanisms that are challenging to detect using this method.