Reach ActiveX or Form objects (textbox) from codebehind in an Excel document

Question

There are several textboxes in an excel file as ActiveX objects and I want to reach them from codebehind.

I am using ClosedXML for other fields, but I am open for ot

Answer 1

You can make file in VBA (in %appdata% folder), and save textboxes value in this file (by example, .ini file).

And after that open file in C#.

VBA (.xlsm file)

'               PtrSafe for 64bit (for 32bit, remove it)
Private Declare PtrSafe Function WritePrivateProfileString Lib "kernel32" Alias "WritePrivateProfileStringA" _
    (ByVal lpApplicationName As String, ByVal lpKeyName As Any, _
    ByVal lpString As Any, ByVal lpFileName As String) As Long

Private Sub TextBox1_Change()
    WritePrivateProfileString "Page1", "TextBox1", TextBox1.Text, "C:\Users\HS\Desktop\exceltab.ini"
End Sub

C:\Users\HS\Desktop\exceltab.ini

[Page1]
TextBox1=ok