By default, the Zoom factor is 0.14 The Zoom factor should be between 0.01 and 0.21. Any other value is reduced to this range. The Zoom event is fired when the user calls in the code the Zoom method or whether the user rotates the mouse wheel. Use the AllowZoom property to disable zooming the view when the user rotates the mouse wheel.

For instance, use the KeyDown event handler to zoom the view when the user presses the + key, like in the following VB sample:

Private Sub Texture1_KeyDown(KeyCode As Integer, Shift As Integer)
    If (KeyCode = vbKeyAdd) Then
        Texture1.Zoom = Texture1.Zoom - 0.01
    Else
        If (KeyCode = vbKeySubtract) Then
            Texture1.Zoom = Texture1.Zoom + 0.01
        End If
    End If
End Sub