When you develop an application in Microsoft Access, your combo boxes will, by default, incorporate autocomplete. However, Visual Basic does not include this intrinsic support. If you want autocomplete in VB, you've got to do it yourself. This tip shows you how.
First, you'll need to add some methods to your form:
- AutoCompleteKeyUp: This method accepts a combo box and KeyEventArgs objects as arguments. When you call this in the KeyUp event of your combo box, the method evaluates what the user has typed and selects the most appropriate match.
- AutoCompleteLeave: Call this method when the Leave event of your combobox is fired. This method simply takes whatever you've finally chosen and cases it properly, according to the matching selection in the combo box.
Let's look at those functions now:
Public Sub AutoCompleteKeyUp(ByVal Combo As ComboBox, _
ByVal e As KeyEventArgs)
Dim strTyped As String
Dim intFoundIndex As Integer
Dim objFoundItem As Object
Dim strFoundText As String
Dim strAppendText As String
' Ignore basic selection keys
Select Case e.KeyCode
Case Keys.Back, Keys.Left, Keys.Right, Keys.Up, _
Keys.Delete, Keys.Down, Keys.CapsLock
Return
End Select
' Find what user has typed in list
strTyped = Combo.Text
intFoundIndex = Combo.FindString(strTyped)
' If found...
If intFoundIndex >= 0 Then
' Get list item (actual type depends on whether data bound)
objFoundItem = Combo.Items(intFoundIndex)
' Use control to resolve text - in case data bound
strFoundText = Combo.GetItemText(objFoundItem)
' Append the typed text to rest of the found string
' (text is set twice due to a combo box quirk:
' on certain platforms, setting just once ignores casing!)
strAppendText = strFoundText.Substring(strTyped.Length)
Combo.Text = strTyped & strAppendText
Combo.Text = strTyped & strAppendText
' Select the appended text
Combo.SelectionStart = strTyped.Length
Combo.SelectionLength = strAppendText.Length
End If
End Sub
Public Sub AutoCompleteLeave(ByVal Combo As ComboBox)
' Correct casing when leaving combo
Dim intFoundIndex As Integer
intFoundIndex = Combo.FindStringExact(Combo.Text)
Combo.SelectedIndex = -1
Combo.SelectedIndex = intFoundIndex
End Sub
And here's how to call these functions from your combo box:
Private Sub ComboBox1_KeyUp(ByVal sender As Object, _
ByVal e As System.Windows.Forms.KeyEventArgs) Handles ComboBox1.KeyUp
AutoCompleteKeyUp(ComboBox1, e)
End Sub
Private Sub ComboBox1_Leave(ByVal sender As Object, _
ByVal e As System.EventArgs) Handles ComboBox1.Leave
AutoCompleteLeave(ComboBox1)
End Sub
