WinRTXamlToolkit.Controls.Calendar.ProcessUpKey C# (CSharp) Method

        internal void ProcessUpKey(bool ctrl, bool shift)
        {
            switch (DisplayMode)
            {
                case CalendarMode.Month:
                    {
                        if (ctrl)
                        {
                            SelectedMonth = DisplayDateInternal;
                            DisplayMode = CalendarMode.Year;
                        }
                        else
                        {
                            DateTime? selectedDate = DateTimeHelper.AddDays(LastSelectedDate.GetValueOrDefault(DateTime.Today), -ColumnsPerMonth);
                            ProcessSelection(shift, selectedDate, -ColumnsPerMonth);
                        }
                        break;
                    }
                case CalendarMode.Year:
                    {
                        if (ctrl)
                        {
                            SelectedYear = SelectedMonth;
                            DisplayMode = CalendarMode.Decade;
                        }
                        else
                        {
                            DateTime? selectedMonth = DateTimeHelper.AddMonths(_selectedMonth, -ColumnsPerYear);
                            OnSelectedMonthChanged(selectedMonth);
                        }
                        break;
                    }
                case CalendarMode.Decade:
                    {
                        if (!ctrl)
                        {
                            DateTime? selectedYear = DateTimeHelper.AddYears(SelectedYear, -ColumnsPerYear);
                            OnSelectedYearChanged(selectedYear);
                        }
                        break;
                    }
            }
        }