Overloads the calculate values method to calculate the values for
        this axis based on the minimum and maximum values, and the number
        of steps desired.
        
        :return     [<variant>, ..]

def calculateValues(self):
        """
        Overloads the calculate values method to calculate the values for
        this axis based on the minimum and maximum values, and the number
        of steps desired.
        
        :return     [<variant>, ..]
        """
        if self.maximum() <= self.minimum():
            return []
        
        max_labels = self.maximumLabelCount()
        seconds = (self.maximum() - self.minimum()).total_seconds()
        step = datetime.timedelta(0, int(round(float(seconds) / max_labels)))
        
        values = []
        value = self.minimum()
        while value <= self.maximum():
            values.append(value)
            value += step
        
        return values