// installs a private instance of GestureHandler, if necessary
static void addGestureListenerTo(final JComponent component, final GestureListener listener) {
final Object value = component.getClientProperty(CLIENT_PROPERTY);
if (value instanceof GestureHandler) {
((GestureHandler) value).addListener(listener);
return;
}
if (value != null) return; // some other garbage is in our client property
final GestureHandler newHandler = new GestureHandler();
newHandler.addListener(listener);
component.putClientProperty(CLIENT_PROPERTY, newHandler);
}
// asks the installed GestureHandler to remove it's listener (does not uninstall the
// GestureHandler)
static void removeGestureListenerFrom(
final JComponent component, final GestureListener listener) {
final Object value = component.getClientProperty(CLIENT_PROPERTY);
if (!(value instanceof GestureHandler)) return;
((GestureHandler) value).removeListener(listener);
}