UDF to delete or move all columns not in array - excel

Question

I am trying to write a UDF that will Move or Delete all columns in an array
This part I have.
I also want to Delete or Move all columns not in the array and this part I am stuck on.
This is Case 2 and 4 of the function
Any help on this is appreciated
Thanks
Edit: Updated with answer provided by David G
Function InvertRng(shtName As String, r As Range) As Range
Dim rng As Range
Dim Rng1 As Range, Rng2 As Range
Set Rng1 = GetUsedRange(shtName, 1, True)
For Each rng In Rng1
If Application.Intersect(rng, r) Is Nothing Then
If InvertRng Is Nothing Then
Set InvertRng = rng
Else
Set InvertRng = Application.Union(InvertRng, rng)
End If
End If
Next
End Function
Original Question
Sub MoveOrDelete_n()
MoveOrDelete 2, "Elements", "NewSheet", Array("Id", "Type", "Description")
End Sub
The Function
Function MoveOrDelete(iwhat As Long, SshtName As String, TshtName As String, arrHeaders As Variant) 'Excel VBA to move Columns based on criteria
Dim wsS As Worksheet, wsT As Worksheet
Dim ar As Variant
Dim fn As Range, r As Range
Dim str As String
Dim i As Long
Set wsS = ThisWorkbook.Sheets(SshtName)
Set wsT = ThisWorkbook.Sheets(TshtName)
For i = 0 To UBound(arrHeaders) 'Loop through the Array
Set fn = wsS.Rows("1:1").Find(arrHeaders(i), LookAt:=xlWhole)
str = str & fn.Address & ","
Next i
'Remove the trailing comma from the string
str = Left(str, Len(str) - 1)
Set r = wsS.Range(str).EntireColumn
Select Case iwhat
Case 1
'Delete all columns IN list
r.Delete
Case 2
'Delete all columns NOT in list
invertR.Delete
Case 3
'Move all columns IN List to NEW Sheet
r.Copy wsT.[a1]
Case 4
'Move all columns NOT in List to NEW SheeT
invertR.Copy wsT.[a1]
End Select
End Function

Answer 1

I found this function that invert the selection, maybe is what you need:
Sub InvertSelection()
'Updateby20140314
Dim rng As Range
Dim Rng1 As Range
Dim Rng2 As Range
Dim OutRng As Range
xTitleId = "KutoolsforExcel"
Set Rng1 = Application.Selection
Set Rng1 = Application.InputBox("Range1 :", xTitleId, Rng1.Address, Type:=8)
Set Rng2 = Application.InputBox("Range2", xTitleId, Type:=8)
For Each rng In Rng2
If Application.Intersect(rng, Rng1) Is Nothing Then
If OutRng Is Nothing Then
Set OutRng = rng
Else
Set OutRng = Application.Union(OutRng, rng)
End If
End If
Next
OutRng.Select
End Sub
https://www.extendoffice.com/documents/excel/762-excel-reverse-selections.html