Skipping Events
The wxWidgets event processing system implements something very close to virtual methods in normal C++, which means that it is possible to alter the behavior of a class by overriding its event handling functions. In many cases, this works even for changing the behavior of native controls. For example, it is possible to filter out selected keystroke events sent by the system to a native text control by overriding wxTextCtrl and defining a handler for key events using EVT_KEY_DOWN. This would indeed prevent any key events from being sent to the native control, which might not be what is desired. In this case, the event handler function has to call wxEvent::Skip to indicate that the search for the event handler should continue.To summarize, instead of explicitly calling the base class version, as you would have done with C++ virtual functions, you should instead call Skip on the event object.For example, to make the derived text control only accept "a" to "z" and "A" to "Z," we would use this code:
void MyTextCtrl::OnChar(wxKeyEvent& event)
{
if ( wxIsalpha( event.KeyCode() ) )
{
// Keycode is within range, so do normal processing.
event.Skip();
}
else
{
// Illegal keystroke. We don't call event.Skip() so the
// event is not processed anywhere else.
wxBell();
}
}
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