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Validates keystrokes for an object's KeyPress event

Validates keystrokes for an object's KeyPress event

API Declarations


'Feel free to use this code freely. If you make enhancements, share them.
'This code does multiple things:
'1. It validates a keystroke based on the ValidChars or InvalidChars, and cancels the keystroke entirely if invalid (sets KeyAscii to 0, which is passed by reference)
'2. If KeyAscii is vbKeyReturn (ENTER key), it swaps the keystroke for a {TAB} action (tabs to the next field, great for 10-key apps)
'3. The PurgeText routine will clean up a string based on the ValidChar or InvalidChar set (necessary if the user pastes a string into a restricted field, which bypasses the check on individual keystrokes)

Global Const InvalidChar_WINFILESYSTEM = "/*?<>|""" 'series of " adds Chr$(34) to the string
Global Const InvalidChar_WINFILENAME = "/\:*?<>|""" 'series of " adds Chr$(34) to the string
Global Const ValidChar_NUMERIC = "1234567890.-"
Global Const ValidChar_NUMERICWHOLE = "1234567890-" '(no decimal)




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        Optional InvalidChar As String = "", Optional AllowCtrlCodes As Boolean = True) As Boolean
    Dim vkPASS As Boolean
    vkPASS = True
    If KeyAscii < 27 Then
        If KeyAscii = vbKeyReturn Then
            KeyAscii = 0      'cancel the ENTER keypress
            Call SendKeys("{TAB}")  'send TAB in its place
        Else
            'ASCII 1-26 = ctrl+A to ctrl+Z
            If Not AllowCtrlCodes Then
                'NOTE: This can cancel Copy, Cut and Paste functionality!
                KeyAscii = 0
                vbPASS = False
            End If
        End If
    Else
        'Check if the character exists in the ValidChars string
        If ValidChars <> "" Then
            If InStr(1, ValidChars, Chr$(KeyAscii)) = 0 Then
                KeyAscii = 0
                vkPASS = False
            End If
        ElseIf InvalidChar <> "" Then
            If InStr(1, InvalidChar, Chr$(KeyAscii)) > 0 Then
                KeyAscii = 0
                vkPASS = False
            End If
        End If
    End If
    ValidateKeystroke = vkPASS
End Function

Public Function ValidateKeyPurgeText(ByVal TextValue As String, Optional ValidChars As String = "", _
        Optional InvalidChar As String = "", Optional AllowCtrlCodes As Boolean = False, _
        Optional AllowNewLine As Boolean = True) As String
    Dim vkRTN As String
    vkRTN = ""
    Dim vkT As Long
    Dim vkSEG As String
    For vkT = 1 To Len(TextValue)
        vkSEG = Mid(TextValue, vkT, 1)
        If Asc(vkSEG) < 27 Then
            If Asc(vkSEG) = 10 Or Asc(vkSEG) = 13 Then
                '10 and 13 are Line Feed and Carriage Return... New Line!
                If AllowNewLine = False Then vkSEG = ""
            Else
                If AllowCtrlCodes = False Then vkSEG = ""
            End If
        Else
            If ValidChars <> "" Then
                'Check if the character exists in the ValidChars string
                If InStr(1, ValidChars, vkSEG) = 0 Then
                    vkSEG = ""
                End If
            ElseIf InvalidChar <> "" Then
                'Check if the character exists in the InvalidChars string
                If InStr(1, InvalidChar, vkSEG) > 0 Then
                    vkSEG = ""
                End If
            End If
        End If
        vkRTN = vkRTN & vkSEG
    Next vkT
    
    ValidateKeyPurgeText = vkRTN
End Function