linking c# gui project and library dll project

Question

This snippet is a helloworld-like example illustrating the framework goal I am trying to achieve. The goal of this project is to control the GUI from a seperate piece of code in C# or VBA, e.g. an automation routine that talks to equipment and other pieces of software. The GUI is there for the benefit of the user not using automation, but I also want to automate pieces of the GUI as if someone were there

I am trying to link a GUI and a COM dll together as stated above without much success.

Both projects work separately.

1. I have verified I can call the COM dll functions.

2. I have also verified the simple GUI works.

3. Now I would like to have functions inside the GUI that are callable from the COM dll.

I thought it was as easy as adding the other project and adding a reference, but I am doing something wrong. It's funny because the code completion makes it seem as I am very close, as you can see from the screenshots.

GUI Project:

namespace GUI_HELLOWORLD
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
        public void Button1_Click(object sender, RoutedEventArgs e)
        {
            MessageBox.Show("Hello World.");
        }
        public void Button1_Click()
        {
            //For the sake of clicking through code - figure out correct method later
            MessageBox.Show("Hello World.");
        }
    }
 }

DLL project:

namespace GUI_COM_LIB
{
    [System.Runtime.InteropServices.ComVisible(true)] //- may not be necessary in some cases?
    public class ZZ_GUI_HELLOWORLD_API_DEMO
    {
        public void SelHello()
        {
            GUI_HELLOWORLD.MainWindow.Button1_Click(); // ERROR!
        }

When adding a reference to the GUI into the COM_LIB dll project, I can see the GUI in the pop up menu, so it's seeing it's there! However when I type GUI_HELLOWORLD.MainWindow., no public functions come up where I would expect to see Button1_Click()

Answer 1

It's never quite that simple with COM components. Have you looked through this ancient tome?

Calling COM Components from .NET Clients

Specifically, have you run TLBIMP on your COM component?

Edit

Check out this Stack Overflow question This Blog Post

Is your Client built as an Excel Add-In? (using Visual Studio Tools for Office)

Answer 2

You need an instance of your window object:

public void SelHello()
{
    var myWindow = new GUI_HELLOWORLD.MainWindow();
    myWindow.Button1_Click();
}

Answer 3

WCF named pipe minimal example

I found the solution in this thread. By using a channel system, an interface can be created and functions from the GUI can be piped over to a dll. The dll is then callable from C#, Excel VBA, or other .NET.