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Old May 6th, 2005, 05:19 AM
Fia Fia is offline
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Default Onkeypress

Hi when I'm creating a numeric textbox I have to override the method
Onkeypress to prevent a user of the control to use the control's Keypress
event. For example the users of the control could write code like this.

Private Sub NumericTextbox1_KeyPress(ByVal sender As Object, ByVal e As
System.Windows.Forms.KeyPressEventArgs) Handles NumericTextbox1.KeyPress
        Me.NumericTextbox1.Text = e.KeyChar
End Sub

And spoil the use of the NumericTextbox

To prevent this code to happen I have to use the code below in the
NumericTextbox's class. I'm not sure why I have to do it like this, so if
anyone can explain that for me I'll be greatful.

Protected Overrides Sub OnKeyPress(ByVal e As
System.Windows.Forms.KeyPressEventArgs)
     If Asc(e.KeyChar) = 8 Then
     ElseIf Not IsNumeric(e.KeyChar) Then
        e.Handled = True
     End If
End Sub

In some books they say I have to have this code also and I don't know why. I
don't notice any difference if I have this line or not.

Public Shadows Event KeyPress(ByVal sender As Object, _
 ByVal e As System.Windows.Forms.KeyPressEventArgs)

And finally I don't understand why I have to override the method Onkeypress,
because when I'm looking at the textbox class in WinCV.exe, I can't find the
metod Onkeypress.
To make the NumericTextbox I inherit from System.Windows.Forms.TextBox.

Can anyone help me with these questions.

Thanks for your answers

Fia








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