Question

this is a totally newbie question since my field is Java and not C# but I got given the task of building a BHO and have reached a point where I need a menu item (inside the tools menu) to call a function within my code.

I read that I have to declare and implement the IOleCommandTarget interface, which I did. Now I need to register this same class as a COM Object.

Apparently to do that I need to declare a couple of functions with [ComRegisterFunction] but even after doing so I cannot register them with regsvr32. And uppon further inspection with DLL Export viewer the functions do not seem to be there 🙁

What am I doing wrong?

Thank you in advance

EDIT:

Ok so from the comments I got I suppose that My COM object is registered correctly but still my problem remains: When I click the newly created menu item I have no reaction or way to debug what’s really going on.

This is my code so far:

using System;
using System.Runtime.InteropServices;
using System.IO;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using SHDocVw;
using MSHTML;
using Microsoft.Win32;
using System.Windows;
using System.Windows.Forms;
using System.Drawing.Imaging;
using System.Drawing;
using System.Diagnostics;
using System.Threading;


[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct OLECMDTEXT {
    public uint cmdtextf;
    public uint cwActual;
    public uint cwBuf;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 100)]
    public char rgwz;
}

[StructLayout(LayoutKind.Sequential)]
public struct OLECMD {
    public uint cmdID;
    public uint cmdf;
}

// Interop definition for IOleCommandTarget. 
[ComImport,
Guid("b722bccb-4e68-101b-a2bc-00aa00404770"),
InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
public interface IOleCommandTarget {
    //IMPORTANT: The order of the methods is critical here. You
    //perform early binding in most cases, so the order of the methods
    //here MUST match the order of their vtable layout (which is determined
    //by their layout in IDL). The interop calls key off the vtable ordering,
    //not the symbolic names. Therefore, if you switched these method declarations
    //and tried to call the Exec method on an IOleCommandTarget interface from your
    //application, it would translate into a call to the QueryStatus method instead.
    void QueryStatus(ref Guid pguidCmdGroup, UInt32 cCmds,
        [MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 1)] OLECMD[] prgCmds, ref OLECMDTEXT CmdText);
    void Exec(ref Guid pguidCmdGroup, uint nCmdId, uint nCmdExecOpt, ref object pvaIn, ref object pvaOut);
}

namespace ANAISBHO {

    [
    ComVisible(true),
    Guid("8a194578-81ea-4850-9911-13ba2d71efbd"),
    ClassInterface(ClassInterfaceType.None)
    ]
    public class BHO : IObjectWithSite, IOleCommandTarget {

        public SHDocVw.WebBrowser webBrowser;

        public HTMLDocument document;

        public static string BHOKEYNAME = "Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\Browser Helper Objects";

        private Guid cmdGuid = new Guid("ED016940-BD5B-11CF-BA4E-00C04FD70816");

        private static Bitmap bmpScreenshot;

        private static Graphics gfxScreenshot;


        public void OnDocumentComplete(object pDisp, ref object URL) {
            document = (HTMLDocument) webBrowser.Document;
        }

        //HKEY_LOCAL_MACHINE\Software\Microsoft\Internet Explorer\Extensions\{GUID}\CLSID
        private static void RegisterCiteNPLMenuEntry() {
            Console.WriteLine("Registrying the CiteNPL menu entry");
            RegistryKey MicrosoftKey = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Default).OpenSubKey("Software").OpenSubKey("Microsoft");
            RegistryKey ExtensionsKey = MicrosoftKey.OpenSubKey("Internet Explorer").OpenSubKey("Extensions", RegistryKeyPermissionCheck.ReadWriteSubTree);
            String GUID = @"{C3E1CD69-3928-4b69-ABEC-936CA3A3BAAA}";

            ExtensionsKey.CreateSubKey(GUID);
            RegistryKey GUIDKey = ExtensionsKey.OpenSubKey(GUID, RegistryKeyPermissionCheck.ReadWriteSubTree);
            String CLSID_Shell_ToolbarExtExec = @"{1FBA04EE-3024-11d2-8F1F-0000F87ABD16}";
            GUIDKey.SetValue("CLSID", CLSID_Shell_ToolbarExtExec, RegistryValueKind.String);
            GUIDKey.SetValue("MenuText", "CiteNPL", RegistryValueKind.String);
            GUIDKey.SetValue("ClsidExtension", "{c4127d56-7114-46da-a853-6ea1b8a199f7}", RegistryValueKind.String);

            GUIDKey.Close();
            ExtensionsKey.Close();
            MicrosoftKey.Close();
        }


        public void QueryStatus(ref Guid pguidCmdGroup, UInt32 cCmds, [MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 1)] OLECMD[] prgCmds, ref OLECMDTEXT CmdText) {
            MessageBox.Show("query");
        }

        public void Exec(ref Guid pguidCmdGroup, uint nCmdId, uint nCmdExecOpt, ref object pvaIn, ref object pvaOut) {
            MessageBox.Show("Exec");
        }

        private void TakeScreenshot() {
            int height = 1024; //webBrowser.Document.Body.ScrollRectangle.Height;
            int width = 1024;  //webBrowser.Document.Body.ScrollRectangle.Width;
            //int left = 0;      //webBrowser.Document.Body.ScrollRectangle.Left;
            //int right = 1024;  //webBrowser.Document.Body.ScrollRectangle.Right;
            System.Drawing.Size browserSize = new System.Drawing.Size(width, height);

            bmpScreenshot = new Bitmap(width, height, PixelFormat.Format32bppArgb);
            gfxScreenshot = Graphics.FromImage(bmpScreenshot);
            gfxScreenshot.CopyFromScreen(Screen.PrimaryScreen.Bounds.X, Screen.PrimaryScreen.Bounds.Y, 0, 0, Screen.PrimaryScreen.Bounds.Size, CopyPixelOperation.SourceCopy);
            bmpScreenshot.Save("c:\\temp.png", ImageFormat.Png);
        }

        public int SetSite(object site) {
            if(site != null) {
                webBrowser = (SHDocVw.WebBrowser) site;
                webBrowser.DocumentComplete += new DWebBrowserEvents2_DocumentCompleteEventHandler(this.OnDocumentComplete);
            } else {
                webBrowser.DocumentComplete -= new DWebBrowserEvents2_DocumentCompleteEventHandler(this.OnDocumentComplete);
                webBrowser = null;
            }

            return 0;
        }

        public int GetSite(ref Guid guid, out IntPtr ppvSite) {
            IntPtr punk = Marshal.GetIUnknownForObject(webBrowser);
            int hr = Marshal.QueryInterface(punk, ref guid, out ppvSite);
            Marshal.Release(punk);

            return hr;
        }

        [ComRegisterFunction]
        public static void RegisterBHO(Type type) {
            Console.WriteLine("Registering the BHO");

            RegisterCiteNPLMenuEntry();
            RegisterBHOInWindowsRegistry(type);
        }

        [ComUnregisterFunction]
        public static void UnregisterBHO(Type type) {
            Console.WriteLine("Unregistering the BHO");
            UnRegisterBHOFromWindowsRegistry(type);
        }

        private static void UnRegisterBHOFromWindowsRegistry(Type type) {
            RegistryKey registryKey = Registry.LocalMachine.OpenSubKey(BHOKEYNAME, true);
            string guid = type.GUID.ToString("B");

            if(registryKey != null) {
                registryKey.DeleteSubKey(guid, false);
            }
        }

        private static void RegisterBHOInWindowsRegistry(Type type) {
            RegistryKey registryKey = Registry.LocalMachine.OpenSubKey(BHOKEYNAME, true);

            if(registryKey == null) {
                registryKey = Registry.LocalMachine.CreateSubKey(BHOKEYNAME);
            }

            string guid = type.GUID.ToString("B");
            RegistryKey ourKey = registryKey.OpenSubKey(guid);

            if(ourKey == null) {
                ourKey = registryKey.CreateSubKey(guid);
            }

            ourKey.SetValue("Alright", 1);
            registryKey.Close();
            ourKey.Close();
        }
    }
}

Answer 1

Since this is a managed dll, you cannot use either regsvr32 or “DLL Export Viewer”.

To register your .Net dll for COM Interop, use Regasm