Wpf WebBrowser Refresh-Collection of common programming errors

You can handle a refresh and differentiate it from navigation. With a little exercise, it can be done by handling DOM document.onreadystatechange and window.onunload events, as well as the underlying WebBrowser ActiveX control’s NavigateComplete2 and DownloadBegin events.

NavigateComplete2 doesn’t get fired for the top WebBrowser object when the page is being refreshed, but it does when navigating. DownloadBegin always gets fired, for any download, navigation or refresh activity, possibly multiple times. window.onunload gets fired before navigation or refresh, and document.onreadystatechange gets fired during navigation or refresh. The rest is the matter of tracking the state transitions. Here is a working example (which still may contain bugs).

C#:

using Microsoft.Win32;
using System;
using System.Diagnostics;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Controls;

namespace WpfWebBrowser
{
    public partial class MainWindow : Window
    {
        bool navigating = false;
        bool loading = false;
        bool loaded = false;

        public MainWindow()
        {
            SetBrowserFeatureControl();
            InitializeComponent();

            this.Loaded += (s, e) =>
            {
                var axWebBrowser = (SHDocVw.WebBrowser)GetActiveXInstance(this.webBrowser);

                axWebBrowser.DownloadBegin += delegate
                {
                    HandleDownloadActivity();
                };

                axWebBrowser.NavigateComplete2 += delegate(object pDisp, ref object URL)
                {
                    // top frame?
                    if (Object.ReferenceEquals(axWebBrowser, pDisp))
                    {
                        this.navigating = true;
                        HandleDownloadActivity();
                    }
                };

                this.webBrowser.Navigate("http://example.com");
            };
        }

        // handler for document.readyState == "complete"
        void DomDocumetCompleteHandler(dynamic domDocument)
        {
            dynamic domWindow = domDocument.parentWindow;

            domWindow.attachEvent("onunload", new DomEventHandler(delegate
            {
                this.loaded = false;
                this.loading = false;
            }));

            var navigated = this.navigating;

            this.navigating = false;
            this.loaded = true;
            this.loading = false;

            MessageBox.Show(navigated ? "Navigated" : "Refreshed");
        }

        void HandleDownloadActivity()
        {
            dynamic domDocument = this.webBrowser.Document;
            if (domDocument == null)
                return;

            if (loading || loaded)
                return;

            this.loading = true;

            if (domDocument.readyState == "complete")
            {
                DomDocumetCompleteHandler(domDocument);
            }
            else
            {
                DomEventHandler handler = null;
                handler = new DomEventHandler(delegate
                {
                    if (domDocument.readyState == "complete")
                    {
                        domDocument.detachEvent("onreadystatechange", handler);
                        DomDocumetCompleteHandler(domDocument);
                    }
                });
                domDocument.attachEvent("onreadystatechange", handler);
            }
        }

        /// 
        /// Get the underlying WebBrowser ActiveX object;
        /// this code depends on SHDocVw.dll COM interop assembly,
        /// generate SHDocVw.dll: "tlbimp.exe ieframe.dll",
        /// and add as a reference to the project
        /// 
        static object GetActiveXInstance(WebBrowser wb)
        {
            return wb.GetType().InvokeMember("ActiveXInstance",
                BindingFlags.GetProperty | BindingFlags.Instance | BindingFlags.NonPublic,
                null, wb, new object[] { }) as SHDocVw.WebBrowser;
        }

        /// 
        /// EventHandler - adaptor to call C# back from JavaScript or DOM event handlers
        /// 
        [ComVisible(true), ClassInterface(ClassInterfaceType.AutoDispatch)]
        public class DomEventHandler
        {
            [ComVisible(false)]
            public delegate void Callback(ref object result, object[] args);

            [ComVisible(false)]
            private Callback _callback;

            [DispId(0)]
            public object Method(params object[] args)
            {
                var result = Type.Missing; // Type.Missing is "undefined" in JavaScript
                _callback(ref result, args);
                return result;
            }

            public DomEventHandler(Callback callback)
            {
                _callback = callback;
            }
        }

        /// 
        /// WebBrowser version control
        /// http://msdn.microsoft.com/en-us/library/ee330730(v=vs.85).aspx#browser_emulation
        /// 
        void SetBrowserFeatureControl()
        {
            // http://msdn.microsoft.com/en-us/library/ee330720(v=vs.85).aspx

            // FeatureControl settings are per-process
            var fileName = System.IO.Path.GetFileName(Process.GetCurrentProcess().MainModule.FileName);

            // make the control is not running inside Visual Studio Designer
            if (String.Compare(fileName, "devenv.exe", true) == 0 || String.Compare(fileName, "XDesProc.exe", true) == 0)
                return;

            // Webpages containing standards-based !DOCTYPE directives are displayed in IE9/IE10 Standards mode.
            SetBrowserFeatureControlKey("FEATURE_BROWSER_EMULATION", fileName, 9000);
        }

        void SetBrowserFeatureControlKey(string feature, string appName, uint value)
        {
            using (var key = Registry.CurrentUser.CreateSubKey(
                String.Concat(@"Software\Microsoft\Internet Explorer\Main\FeatureControl\", feature),
                RegistryKeyPermissionCheck.ReadWriteSubTree))
            {
                key.SetValue(appName, (UInt32)value, RegistryValueKind.DWord);
            }
        }

    }
}

XAML: