write a com control in c# and use it in MFC

Question

if this possible to write a com control or activex in C# and use it in MFC ?

Answer 1

Yes. First, you need to create COM object. Below is a very simple example.

[Guid("123565C4-C5FA-4512-A560-1D47F9FDFA20")]
public interface IDoSomething
{
    [DispId(1)]
    string Name { get; }

    [DispId(2)]
    int DoSomething();
}

[ComVisible(true)]
[Guid("12AC8095-BD27-4de8-A30B-991940666927")]
[ClassInterface(ClassInterfaceType.None)]
public sealed class DoSomething: IDoSomething
{
    public DoSomething()
    {
    }

    public string Name
    {
        get { return ""; }
    }

    public int DoSomething()
    {
        return 4; //random number
    }
}

After that you need to regasm your assembly. The regasm tool will add the necessary registry COM entries:

regasm.exe /tlb component.dll

/tlb is necessary to generate the type library to be imported in your MFC application.

Once your assembly is registered, you can call DoSomething in your MFC application like any other COM objects.

Check this link for more information.

Answer 2

This is a bit outside my normal territory, as I don't interact with .NET Interop technology all that much.

It is possible to create what's called a COM Callable Wrapper around your C# control/class to make it accessible to any COM-aware program. I won't duplicate Francis B's answer because it's fairly complete as it stands.

The big question is whether a visual C# control works seamlessly within an MFC window. That's not something I can answer, but my best advice would be to prepare for a bumpy road ahead. Please see http://bytes.com/topic/net/answers/430618-c-control-mfc-window-frame for more detail.