Adding a horizontal scroll bar to a listbox

Option Explicit

Private Declare Function SendMessageA Lib "user32" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long


'Purpose : Adds items to a listbox and if neccessary sets the
' width of the horizontal scroll bar to the maximum width of the
' items in the listbox.
'Inputs : lbListbox The listbox to add the item to.
' sItemText The text to add to the listbox.
' [iIndex] The position within the object where the new item or row is placed.
'Outputs : Returns True on success
'Notes :
'Revisions :
'Assumptions :

Function ListboxAddItem(lbListbox As ListBox, sItemText As String, Optional iIndex As Integer = -1) as Boolean
Dim fTextWidth As Single, fExistScrollWidth As Single
Dim oParentFont As StdFont
Const LB_SETHORIZONTALEXTENT = &H194, LB_GETHORIZONTALEXTENT = &H193

On Error Resume Next

'Add item to listbox
If iIndex > -1 Then
lbListbox.AddItem sItemText, iIndex
Else
lbListbox.AddItem sItemText
End If

'Store the form's original font
Set oParentFont = lbListbox.Parent.Font
'Set the form's font to the listbox's font
Set lbListbox.Parent.Font = lbListbox.Font
'Get width of text on the form
fTextWidth = lbListbox.Parent.TextWidth(sItemText & " ") 'Extra space allows for vertical scroll bar
'Restore the form's font
Set lbListbox.Parent.Font = oParentFont

'Get the width of the existing scroll bar
fExistScrollWidth = SendMessageA(lbListbox.hwnd, LB_GETHORIZONTALEXTENT, 0, 0)

If lbListbox.Parent.ScaleMode = vbTwips Then
'Change twips to pixels
fTextWidth = fTextWidth / Screen.TwipsPerPixelX
End If

If fTextWidth > fExistScrollWidth Then
'Increase width of scroll bar
Call SendMessageA(lbListbox.hwnd, LB_SETHORIZONTALEXTENT, fTextWidth, 0)
End If
ListboxAddItem = (Err.Number = 0)
End Function


'Purpose : Modifies the text of an item in a listbox and if neccessary sets the
' width of the horizontal scroll bar to the maximum width of the
' items in the listbox.
'Inputs : lbListbox The listbox to update the item in.
' sNewItemText The new text for the item in the listbox.
' [iIndex] The index of the item to update within the listbox.
'Outputs : Returns True on Success
'Notes :
'Revisions :
'Assumptions :

Function ListboxUpdateItem(lbListbox As ListBox, sNewItemText As String, iIndex As Integer) As Boolean
Dim fTextWidth As Single, fExistScrollWidth As Single
Dim oParentFont As StdFont
Const LB_SETHORIZONTALEXTENT = &H194, LB_GETHORIZONTALEXTENT = &H193

'Add item to listbox
On Error GoTo ErrFailed
If lbListbox.List(iIndex) <> sNewItemText Then
lbListbox.List(iIndex) = sNewItemText
'Get width of text
Set oParentFont = lbListbox.Parent.Font
Set lbListbox.Parent.Font = lbListbox.Font
fTextWidth = lbListbox.Parent.TextWidth(sNewItemText & " ") 'Extra space allows for vertical scroll bar
Set lbListbox.Parent.Font = oParentFont
fExistScrollWidth = SendMessageA(lbListbox.hwnd, LB_GETHORIZONTALEXTENT, 0, 0)

If lbListbox.Parent.ScaleMode = vbTwips Then
'Change twips to pixels
fTextWidth = fTextWidth / Screen.TwipsPerPixelX
End If

If fTextWidth > fExistScrollWidth Then
'Increase width of scroll bar
Call SendMessageA(lbListbox.hwnd, LB_SETHORIZONTALEXTENT, fTextWidth, 0)
End If
End If
ListboxUpdateItem = True

Exit Function

ErrFailed:
Debug.Print "Error in ListboxAddItem: " & lbListbox.Name & " Description: " & Err.Description
ListboxUpdateItem = False
End Function


'Purpose : Adds a horizontal scroll bar to a listbox
'Inputs : lbListbox The listbox to add the scrollbar to.
'Outputs : Returns True on success
'Notes :
'Revisions :
'Assumptions :

Function ListboxAddHorizontalScollBar(lbListbox As ListBox) As Boolean
On Error GoTo ErrFailed
Dim fTextWidth As Single
Dim oParentFont As StdFont, fExistScrollWidth As Single
Dim lThisListItem As Long, fMaxScollWidth As Single, lMaxTextLen As Long
Const LB_SETHORIZONTALEXTENT = &H194, LB_GETHORIZONTALEXTENT = &H193

'Add item to listbox
On Error GoTo ErrFailed
'Set the parent font
Set oParentFont = lbListbox.Parent.font
Set lbListbox.Parent.font = lbListbox.font
Set lbListbox.Parent.font = oParentFont

'Determine max. length of text
For lThisListItem = 0 To lbListbox.ListCount - 1
If Len(lbListbox.list(lThisListItem)) > lMaxTextLen Then
lMaxTextLen = Len(lbListbox.list(lThisListItem))
End If
Next

'Get the text length
fTextWidth = lbListbox.Parent.TextWidth(String(lMaxTextLen + 1, "W")) 'Extra space allows for vertical scroll bar
'Restore the form's font
Set lbListbox.Parent.font = oParentFont

'Get the width of the existing scroll bar
fExistScrollWidth = SendMessage(lbListbox.hwnd, LB_GETHORIZONTALEXTENT, 0, 0)

If lbListbox.Parent.ScaleMode = vbTwips Then
'Change twips to pixels
fTextWidth = fTextWidth / Screen.TwipsPerPixelX
End If

If fTextWidth > fExistScrollWidth Then
'Increase width of scroll bar
Call SendMessage(lbListbox.hwnd, LB_SETHORIZONTALEXTENT, fTextWidth, 0)
End If
ListboxAddHorizontalScollBar = (err.number = 0)

Exit Function

ErrFailed:
Debug.Print err.description
Debug.Assert False
ListboxAddHorizontalScollBar = (err.number = 0)
End Function

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