def METHOD_NAME(self):
    """Mostly internal routine to update the limits.  Shouldn't need to
    be called explicitly in most cases.
    """
    if len(self) == 0:
        self.limits = np.array([[0.0, 0.0], [0.0, 0.0]])
    else:
        x_min, x_max = self.buf[self.rear][0], self.buf[self.front][0]
        y_min, y_max = self.slmm.get_minmax()
        self.limits = np.array([[x_min, y_min], [x_max, y_max]])