I have a C# Excel Add-in project ‘MyExcelAddIn’ that has a public method Foo() to do something complex. For testing purposes, the add-in also defines a toolbar button which is wired to Foo() so I can test this and verify that clicking the button calls Foo() and does what I want it to do. This is fine.
Now I want to call this method from a C# Windows Forms project. In the Windows Forms project I can create an Excel instance and make it visible and verify that my VSTO add-in is running as I can see the button and it works. But I can’t work out how to call Foo() programatically from the Windows Forms project. I’ve googled a bit and got as far as getting the ‘MyExcelAddIn’ COMAddIn object, but can’t work out how to call Foo().
It looks something like this:
// Create Excel and make it visible Application excelApp = new Application(); excelApp.Visible = true; // I know my VSTO add-in is running because I can see my test button // Now get a reference to my VSTO add-in Microsoft.Office.Core.COMAddIns comAddIns = _excelApp.COMAddIns; object addinName = 'MyExcelAddIn'; Microsoft.Office.Core.COMAddIn myAddin = comAddIns.Item(ref addinName); // This works, but now what? How do I make a call on myAddin? // Note that myAddin.Object is null... So I want to know what I can do to call Foo() from my Windows Forms application. Note that I have full control over both the Windows Forms application and the add-in and I suspect I have to make changes to both of them (particularly the add-in) but I have no idea how to do this.
Note that this is a VS2008 C# application and I’m using Excel 2003.
I’m using the SendMessage Win32 API to do this. My C# Add-in creates a ‘NativeWindow’ with a uniqe window title that the WinForm app can locate.