def mpl_redraw_callback(event, tax):
    """
    Callback to properly rotate and redraw text labels when the plot is drawn
    or resized.

    Parameters
    ----------
    event: a matplotlib event
        either 'resize_event' or 'draw_event'
    tax: TernaryAxesSubplot
         the TernaryAxesSubplot
    """
    tax._redraw_labels()
