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

        internal void ProcessLeftKey(bool shift)
        {
            switch (DisplayMode)
            {
                case CalendarMode.Month:
                    {
                        DateTime? selectedDate = DateTimeHelper.AddDays(LastSelectedDate.GetValueOrDefault(DateTime.Today), -1);
                        ProcessSelection(shift, selectedDate, -1);
                        break;
                    }
                case CalendarMode.Year:
                    {
                        DateTime? selectedMonth = DateTimeHelper.AddMonths(_selectedMonth, -1);
                        OnSelectedMonthChanged(selectedMonth);
                        break;
                    }
                case CalendarMode.Decade:
                    {
                        DateTime? selectedYear = DateTimeHelper.AddYears(SelectedYear, -1);
                        OnSelectedYearChanged(selectedYear);
                        break;
                    }
            }
        }