Visual Basic Programming Code Examples
Visual Basic > Forms Code Examples
Make a Combo Box Auto Complete
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Make a Combo Box Auto Complete
If you want you VB Combo boxes to automatically complete then use the following
code:
'API call (add to declaration section of form or module)
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
'Purpose : Auto completes a combo box during the KeyPress event, based on the text typed in by the user.
'Inputs : cboComplete The combo box to auto complete (completes the current text based on
' the listitems in the combo).
' KeyAscii The Ascii value of the key pressed (as supplied by the keypress event)
' [bLimitToList] If True, will only allow the user to enter values which are in the combos list.
'Outputs : Returns the KeyAscii value or zero if bLimitToList = True and the user types an invalid character.
'Notes : Call the routine from the _KeyPress event of the combo.
' The combo must be of a vbComboDropDown style, eg. KeyAscii = ComboAutoComplete(Combo1, KeyAscii, False)
Public Function ComboAutoComplete(ByRef cboComplete As ComboBox, ByVal KeyAscii As Integer, Optional ByVal bLimitToList As Boolean = False) As Long
Dim lRetVal As Long
Dim sSearch As String
Const CB_ERR = (-1), CB_FINDSTRING = &H14C
On Error GoTo ErrFailed
If cboComplete.Style <> vbComboDropdown Then
Debug.Print "Error in ComboAutoComplete. Combo must be of the style vbComboDropdown..."
Debug.Assert False
'Return the KeyAscii
ComboAutoComplete = KeyAscii
Exit Function
End If
If KeyAscii = 8 Then
'Pressed delete
If cboComplete.SelStart <= 1 Then
'Last character, clear combo.
cboComplete.Text = ""
ComboAutoComplete = 0
Exit Function
End If
'Delete text
If cboComplete.SelLength = 0 Then
'Delete a single character
sSearch = UCase$(Left$(cboComplete.Text, Len(cboComplete) - 1))
Else
'Delete the selected text
sSearch = Left$(cboComplete.Text, cboComplete.SelStart - 1)
End If
ElseIf KeyAscii < 32 Or KeyAscii > 127 Then
'Invalid keyboard characters
Exit Function
Else
'Append the new text to the combo text
If cboComplete.SelLength = 0 Then
'Append a character
sSearch = UCase$(cboComplete.Text & Chr$(KeyAscii))
Else
'Insert a character
sSearch = Left$(cboComplete.Text, cboComplete.SelStart) & Chr$(KeyAscii)
End If
End If
'Find the closest match
lRetVal = SendMessage(cboComplete.hwnd, CB_FINDSTRING, -1, ByVal sSearch)
If lRetVal = CB_ERR Then
'Did not find a matching item in list
If bLimitToList = True Then
'Block the KeyAscii
ComboAutoComplete = 0
Else
'Return the KeyAscii
ComboAutoComplete = KeyAscii
End If
Else
'Found a matching item in list
cboComplete.ListIndex = lRetVal
cboComplete.SelStart = Len(sSearch)
cboComplete.SelLength = Len(cboComplete.Text) - cboComplete.SelStart
ComboAutoComplete = 0
End If
Exit Function
ErrFailed:
'Return the keycode
ComboAutoComplete = KeyAscii
End Function
'Demonstration:
'To call the ComboAutoComplete routine, place the following code in the form in the combo keypress event.
Private Sub Combo1_KeyPress(KeyAscii As Integer)
KeyAscii = ComboAutoComplete(Combo1, KeyAscii, False)
End Sub
