WebBrowser.Document.ExecCommand with "Copy" parameter is not working in C# windows application

Question

I am trying to convert HTML text into RTF in C# windows application. For that,

• I have created one sample windows application in C#.
• Used Web Browser control.
• Load HTML text into it.
• Called web browser's document's object ExecCommand method with "Select" and "Copy" parameter one after the other.
• Select command selects the text but Copy command does not copy selected text to the clipboard.

Following is the code that I have used:

 //Load HTML text
 System.Windows.Forms.WebBrowser webBrowser = new System.Windows.Forms.WebBrowser();
 webBrowser.IsWebBrowserContextMenuEnabled = true;
 webBrowser.Navigate("about:blank");
 webBrowser.Document.Write(htmlText);//htmlText = Valid HTML text

 //Copy formatted text from web browser
 webBrowser.Document.ExecCommand("SelectAll", false, null);
 webBrowser.Document.ExecCommand("Copy", false, null); // NOT WORKING

 //Paste copied text from clipboard to Rich Text Box control
 using (System.Windows.Forms.RichTextBox objRichTextBox = new System.Windows.Forms.RichTextBox())
       {
           objRichTextBox.SelectAll();
           objRichTextBox.Paste();
           string rtfTrxt = objRichTextBox.Rtf;
       }

Notes:

• I have also marked Main method as a STAThreadAttribute
• This is not work on the client system (Windows Server 2019)
• Works fine on my system (Windows 7 32 bits)
• Browser version is same on my system and client ststem i.e. IE 11
• We don't want to use any paid tool like SautinSoft.

Answer 1

I've used this solution for our task:

 // The conversion process will be done completely in memory.
        string inpFile = @"..\..\..\example.html";
        string outFile = @"ResultStream.rtf";
        byte[] inpData = File.ReadAllBytes(inpFile);
        byte[] outData = null;

        using (MemoryStream msInp = new MemoryStream(inpData))
        {

            // Load a document.
            DocumentCore dc = DocumentCore.Load(msInp, new HtmlLoadOptions());

            // Save the document to RTF format.
            using (MemoryStream outMs = new MemoryStream())
            {
                dc.Save(outMs, new RtfSaveOptions() );
                outData = outMs.ToArray();                    
            }
            // Show the result for demonstration purposes.
            if (outData != null)
            {
                File.WriteAllBytes(outFile, outData);
                System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo(outFile) { UseShellExecute = true });
            }

Answer 2

I had the same problem. This helped:

            webBrowser.DocumentText = value;
            while (webBrowser.DocumentText != value) Application.DoEvents();
            webBrowser.Document.ExecCommand("SelectAll", false, null);
            webBrowser.Document.ExecCommand("Copy", false, null);
            richTextBoxActually.Text = "";
            richTextBoxActually.Paste();

Probably it takes several iterations for wb to draw text that can be copied then.