Sets the timescale value for this widget to the inputed value.
        
        :param      timescale | <XGanttWidget.Timescale>

def setTimescale( self, timescale ):
        """
        Sets the timescale value for this widget to the inputed value.
        
        :param      timescale | <XGanttWidget.Timescale>
        """
        self._timescale = timescale
        
        # show hour/minute scale
        if timescale == XGanttWidget.Timescale.Minute:
            self._cellWidth = 60 # (60 seconds)
            self._dateStart = QDate.currentDate()
            self._timeStart = QTime(0, 0, 0)
            
            self._dateEnd = QDate.currentDate()
            self._timeEnd = QTime(23, 59, 59)
            
        elif timescale == XGanttWidget.Timescale.Hour:
            self._cellWidth = 30 # (60 seconds / 2.0)
            
            self._dateStart = QDate.currentDate()
            self._timeStart = QTime(0, 0, 0)
            
            self._dateEnd = QDate.currentDate()
            self._timeEnd = QTime(23, 59, 59)
        
        # show day/hour scale
        elif timescale == XGanttWidget.Timescale.Day:
            self._cellWidth = 30 # (60 minutes / 2.0)
            
            self._dateStart = QDate.currentDate().addDays(-7)
            self._timeStart = QTime(0, 0, 0)
            
            self._dateEnd = QDate.currentDate().addDays(7)
            self._timeEnd = QTime(23, 59, 59)