SpecialCells causing SheetSelectionChange event in Excel 2010 - excel

Question

I have a test Macro
Sub test()
Dim rSrcMatrix As Range
Set rSrcMatrix = Sheets("Code Matrix").Range("Xfer_To_Xfer_Matrix").Range("A1")
Set rSrcMatrix = rSrcMatrix.Resize(rSrcMatrix.SpecialCells(xlCellTypeLastCell).Row, rSrcMatrix.SpecialCells(xlCellTypeLastCell).Column)
End Sub
I am using this macro to test my COM addin that I have created in VS2010. I have delegated the SheetSelectionChange event in the addin to some function.
Now I notice that whenever I run this macro, Excel fires the SheetSelectionChange event 4 times and my addin calls the associated method for that many times.
Is there anything that I am missing or is this a bug in excel?

Answer 1

I believe and I could be wrong because I couldn't find an MSDN article to prove it but SpecialCells performs a type of selection and triggers the Worksheet_SelectionChange or the Workbook_SheetSelectionChange event and hence you need to switch off events.
Here is a simple way to test it.
Place this code in the Sheet Code Area
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
MsgBox "Damn! The SpecialCells caused me to pop up!!!"
End Sub
Sub test()
Debug.Print ActiveSheet.Cells.SpecialCells(xlCellTypeLastCell).Row
End Sub
Worksheet_SelectionChange and Workbook_SheetSelectionChange do the same job. Worksheet_SelectionChange is used in the sheet code are for a specific sheet. And Workbook_SheetSelectionChange is used when you want the event to fire across all the sheets in that workbook.
YOUR QUESTION FROM THE COMMENT: What if we wanted to associate another event with that line of code. In that case, we cannot suppress the event.
Now, we have two alternatives. Based on your above question we cannot use Alternative One. So you may directly skip to Alternative 2
ALTERNATIVE 1
Switch Off Events
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
On Error GoTo Whoa
Application.EnableEvents = False
'
'~~> YOUR CODE
'
Letscontinue:
Application.EnableEvents = True
Exit Sub
Whoa:
MsgBox Err.Description
Resume Letscontinue
End Sub
ALTERNATIVE 2
Instead of using SpecialCells to find the last row or the last column, we will use .Find.
Sub test()
Dim ws As Worksheet
Dim rSrcMatrix As Range
Dim Lrow As Long, LCol As Long
Set ws = ThisWorkbook.Sheets("Code Matrix")
With ws
If Application.WorksheetFunction.CountA(.Cells) <> 0 Then
Lrow = .Cells.Find(What:="*", _
After:=.Range("A1"), _
Lookat:=xlPart, _
LookIn:=xlFormulas, _
SearchOrder:=xlByRows, _
SearchDirection:=xlPrevious, _
MatchCase:=False).Row
LCol = .Cells.Find(What:="*", _
After:=.Range("A1"), _
Lookat:=xlPart, _
LookIn:=xlFormulas, _
SearchOrder:=xlByColumns, _
SearchDirection:=xlPrevious, _
MatchCase:=False).Column
Else
Lrow = 1
End If
Set rSrcMatrix = .Range("Xfer_To_Xfer_Matrix").Range("A1")
Set rSrcMatrix = rSrcMatrix.Resize(Lrow, LCol)
Debug.Print rSrcMatrix.Address
End With
End Sub

Answer 2

Based on #Siddharth Rout technique, here is a method that will return the last cell of a Worksheet.UsedRange (see my comments below his answer)
Function GetLastCellEmpty(rng As Range) As Range
Set m_rngCheck = rng
Set m_rngFound = m_rngCheck.Find(What:="", _
LookIn:=XlFindLookIn.xlFormulas, _
Lookat:=XlLookAt.xlPart, _
SearchDirection:=XlSearchDirection.xlPrevious)
Set GetLastCellEmpty = m_rngFound
End Function
Function GetLastCellUsedRange(ws As Worksheet) As Range
Set GetLastCellUsedRange = GetLastCellEmpty(ws.UsedRange.Offset(1, 1)).Offset(-1, -1)
End Function