Handle COM events in C# using Reflection

Question

I have a COM object with the main interface and the events interface (from the IDL file):

[
    uuid(<interfaceId>,
    helpstring("AxBitViewerWidget Interface")
]
dispinterface IAxBitViewerWidget
{
    ...
};

[
    uuid(<eventsId>),
    helpstring("AxBitViewerWidget Events Interface")
]
dispinterface IAxBitViewerWidgetEvents
{
    ...
};

[
    aggregatable,
    helpstring("AxBitViewerWidget Class"),
    uuid(<mainClassId>), 
    control
]
coclass AxBitViewerWidget
{
    [default] dispinterface IAxBitViewerWidget;
    [default, source] dispinterface IAxBitViewerWidgetEvents;
};

It was automatically created by Active Qt. Then in C# (in another dll) I want to connect to this COM object and handle its events. The C# class is inherited from AxHost. All COM types are dynamic in my example and used via Reflection. Here is the snippet:

public class BitViewerEx : AxHost
{
    public BitViewerEx()
      : base(<mainClassId>)
    {
    }

    private void Initialize()
    {
        try
        {
            object ocx = GetOcx();
            if (ocx != null)
            {
                Type ocxType = ocx.GetType();
                Guid eventsGuid = new Guid(<eventsId>);
                Type eventsType = Type.GetTypeFromCLSID(eventsGuid);                
                var sinkEventsInterfaceObj = CreateInstanceCore(eventsGuid);

                // runtime error here
                var cookie = new ConnectionPointCookie(ocx, sinkEventsInterfaceObj, eventsType);
            }
        }
        catch (Exception ex)
        {
            System.Diagnostics.Trace.WriteLine(ex.ToString());
        }
    }
}

When calling ConnectionPointCookie from the above - an error occurs (approximately translated from localized message): "Cannot execute Advise() for the event interface '__ComObject'".

Is my code correct? How to correctly connect AxBase to the COM object events? (for dynamic types case, cannot use IAxBitViewerWidgetEvents etc. in C# code)

P.S.: class methods (not events) are called without an issue, like:

ocx.GetType().InvokeMember("initialize", System.Reflection.BindingFlags.InvokeMethod,
                                                null, ocx, new object[] { this.argum1, this.argum2 });

P.S.2: The following code returns an empty array:

System.Reflection.EventInfo[] arr = ocx.GetType().GetEvents();

Answer 1

Finally I got it working. The main class is inherited like this

public class BitViewerEx : AxHost, IBitViewerEvents

where IBitViewerEvents is (based on the contents of the corresponding auto-generated .idl file)

// Methods should be like signals in the Qt active-x class with the bit viewer.
// DispIds are taken from the .idl file for the corresponding methods.
[ComImport, Guid(<eventsId>)]
public interface IBitViewerEvents
{
    [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime), DispId(8)]
    void started();

    [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime), DispId(9)]
    void stopped();
}

Then the connection code for all events is simplified to:

using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Runtime.CompilerServices;

...

private void Initialize() // BitViewerEx class member
{
    try
    {
        object ocx = GetOcx();
        if (ocx != null)
        {
            ocx.GetType().InvokeMember("initialize", System.Reflection.BindingFlags.InvokeMethod,
                                    null, ocx, new object[] { this.deviceAddress, this.cellAddress });

            var cookie = new ConnectionPointCookie(ocx, this, typeof(IBitViewerEvents));
        }
    }
    catch (Exception ex)
    {
        System.Diagnostics.Trace.WriteLine(ex.ToString());
    }
}