Enable DateCalculator

src/Calculator.Shared/Calculator.Shared.projitems

@@ -39,6 +39,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Common\CalculatorButtonUser.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Common\CalculatorDisplay.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Common\CopyPasteManager.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Common\DateCalculator.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Common\DelegateCommand.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Common\DisplayExpressionToken.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Common\EngineResourceProvider.cs" />
@@ -48,6 +49,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Common\MyVirtualKey.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Common\NavCategory.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Common\TitleBarHelper.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Common\TraceLogger.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Common\Utils.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\CalculationResult.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\CalculationResultAutomationPeer.cs" />

src/Calculator.Shared/Common/DateCalculator.cs

@@ -0,0 +1,377 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Windows.Globalization;
+
+namespace CalculatorApp.Common.DateCalculation
+{
+	[Flags]
+	public enum DateUnit
+	{
+		Year = 0x01,
+		Month = 0x02,
+		Week = 0x04,
+		Day = 0x08
+	};
+
+    // Struct to store the difference between two Dates in the form of Years, Months , Weeks
+    public struct DateDifference
+	{
+		public int year;
+        public int month;
+        public int week;
+        public int day;
+    };
+
+	public class DateCalculationEngine
+	{
+		const ulong c_millisecond = 10000;
+		const ulong c_second = 1000 * c_millisecond;
+		const ulong c_minute = 60 * c_second;
+		const ulong c_hour = 60 * c_minute;
+		const ulong c_day = 24 * c_hour;
+
+		const int c_unitsOfDate = 4;          // Units Year,Month,Week,Day
+		const int c_unitsGreaterThanDays = 3; // Units Greater than Days (Year/Month/Week) 3
+		const int c_daysInWeek = 7;
+
+		private Calendar m_calendar;
+
+		public DateCalculationEngine(string calendarIdentifier)
+		{
+			m_calendar = new Calendar();
+			m_calendar.ChangeTimeZone("UTC");
+			m_calendar.ChangeCalendarSystem(calendarIdentifier);
+		}
+
+		// Adding Duration to a Date
+		// Returns: True if function succeeds to calculate the date else returns False
+		public bool AddDuration( DateTime startDate,  DateDifference duration, out DateTime endDate)
+		{
+		    var currentCalendarSystem = m_calendar.GetCalendarSystem();
+
+		    try
+		    {
+		        m_calendar.SetDateTime(startDate);
+
+		        // The Japanese Era system can have multiple year partitions within the same year.
+		        // For example, April 30, 2019 is denoted April 30, Heisei 31; May 1, 2019 is denoted as May 1, Reiwa 1.
+		        // The Calendar treats Heisei 31 and Reiwa 1 as separate years, which results in some unexpected behaviors where subtracting a year from Reiwa 1 results
+		        // in a date in Heisei 31. To provide the expected result across era boundaries, we first convert the Japanese era system to a Gregorian system, do date
+		        // math, and then convert back to the Japanese era system. This works because the Japanese era system maintains the same year/month boundaries and
+		        // durations as the Gregorian system and is only different in display value.
+		        if (currentCalendarSystem == CalendarIdentifiers.Japanese)
+		        {
+		            m_calendar.ChangeCalendarSystem(CalendarIdentifiers.Gregorian);
+		        }
+
+		        if (duration.year != 0)
+		        {
+		            m_calendar.AddYears(duration.year);
+		        }
+		        if (duration.month != 0)
+		        {
+		            m_calendar.AddMonths(duration.month);
+		        }
+		        if (duration.day != 0)
+		        {
+		            m_calendar.AddDays(duration.day);
+		        }
+
+		        endDate = m_calendar.GetDateTime().DateTime;
+		    }
+		    catch (ArgumentException ex)
+		    {
+		        // ensure that we revert to the correct calendar system
+		        m_calendar.ChangeCalendarSystem(currentCalendarSystem);
+
+		        // Do nothing
+				endDate = default(DateTime);
+		        return false;
+		    }
+
+		    m_calendar.ChangeCalendarSystem(currentCalendarSystem);
+
+		    return true;
+		}
+
+		// Subtracting Duration from a Date
+		// Returns: True if function succeeds to calculate the date else returns False
+		public bool SubtractDuration( DateTime startDate,  DateDifference duration, out DateTime endDate)
+		{
+		    var currentCalendarSystem = m_calendar.GetCalendarSystem();
+
+		    // For Subtract the Algorithm is different than Add. Here the smaller units are subtracted first
+		    // and then the larger units.
+		    try
+		    {
+		        m_calendar.SetDateTime(startDate);
+
+		        // The Japanese Era system can have multiple year partitions within the same year.
+		        // For example, April 30, 2019 is denoted April 30, Heisei 31; May 1, 2019 is denoted as May 1, Reiwa 1.
+		        // The Calendar treats Heisei 31 and Reiwa 1 as separate years, which results in some unexpected behaviors where subtracting a year from Reiwa 1 results
+		        // in a date in Heisei 31. To provide the expected result across era boundaries, we first convert the Japanese era system to a Gregorian system, do date
+		        // math, and then convert back to the Japanese era system. This works because the Japanese era system maintains the same year/month boundaries and
+		        // durations as the Gregorian system and is only different in display value.
+		        if (currentCalendarSystem == CalendarIdentifiers.Japanese)
+		        {
+		            m_calendar.ChangeCalendarSystem(CalendarIdentifiers.Gregorian);
+		        }
+
+		        if (duration.day != 0)
+		        {
+		            m_calendar.AddDays(-duration.day);
+		        }
+		        if (duration.month != 0)
+		        {
+		            m_calendar.AddMonths(-duration.month);
+		        }
+		        if (duration.year != 0)
+		        {
+		            m_calendar.AddYears(-duration.year);
+		        }
+		        endDate = m_calendar.GetDateTime().DateTime;
+		    }
+		    catch (ArgumentException ex)
+		    {
+		        // ensure that we revert to the correct calendar system
+		        m_calendar.ChangeCalendarSystem(currentCalendarSystem);
+
+		        // Do nothing
+				endDate = default(DateTime);
+		        return false;
+		    }
+
+		    m_calendar.ChangeCalendarSystem(currentCalendarSystem);
+
+		    // Check that the UniversalTime value is not negative
+		    return (endDate.ToUniversalTime().Ticks >= 0);
+		}
+
+		// Calculate the difference between two dates
+		public void GetDateDifference( DateTime date1,  DateTime date2,  DateUnit outputFormat, out DateDifference difference)
+		{
+		    DateTime startDate;
+		    DateTime endDate;
+		    DateTime pivotDate;
+		    DateTime tempPivotDate;
+		    uint daysDiff = 0;
+		    uint[] differenceInDates = new uint[c_unitsOfDate];
+
+		    if (date1.ToUniversalTime() < date2.ToUniversalTime())
+		    {
+		        startDate = date1;
+		        endDate = date2;
+		    }
+		    else
+		    {
+		        startDate = date2;
+		        endDate = date1;
+		    }
+
+		    pivotDate = startDate;
+
+		    daysDiff = (uint)GetDifferenceInDays(startDate, endDate);
+
+		    // If output has units other than days
+		    // 0th bit: Year, 1st bit: Month, 2nd bit: Week, 3rd bit: Day
+		    if (((int)(outputFormat) & 7) != 0)
+		    {
+		        uint daysInMonth;
+		        uint approximateDaysInYear;
+
+		        // If we're unable to calculate the days-in-month or days-in-year, we'll leave the values at 0.
+		        if (TryGetCalendarDaysInMonth(startDate, out daysInMonth) && TryGetCalendarDaysInYear(endDate, out approximateDaysInYear))
+		        {
+		            uint[] daysIn = new uint[c_unitsOfDate] { approximateDaysInYear, daysInMonth, c_daysInWeek, 1 };
+
+		            for (int unitIndex = 0; unitIndex < c_unitsGreaterThanDays; unitIndex++)
+		            {
+		                tempPivotDate = pivotDate;
+
+		                // Check if the bit flag is set for the date unit
+		                DateUnit dateUnit = (DateUnit)(1 << unitIndex);
+
+		                if ((int)(outputFormat & dateUnit) != 0)
+		                {
+		                    bool isEndDateHit = false;
+		                    differenceInDates[unitIndex] = (daysDiff / daysIn[unitIndex]);
+
+		                    if (differenceInDates[unitIndex] != 0)
+		                    {
+		                        try
+		                        {
+		                            pivotDate = AdjustCalendarDate(pivotDate, dateUnit, (int)(differenceInDates[unitIndex]));
+		                        }
+		                        catch (ArgumentException)
+		                        {
+		                            // Operation failed due to out of bound result
+		                            // Do nothing
+		                            differenceInDates[unitIndex] = 0;
+		                        }
+		                    }
+
+		                    int tempDaysDiff;
+
+		                    do
+		                    {
+		                        tempDaysDiff = GetDifferenceInDays(pivotDate, endDate);
+
+		                        if (tempDaysDiff < 0)
+		                        {
+		                            // pivotDate has gone over the end date; start from the beginning of this unit
+		                            differenceInDates[unitIndex] -= 1;
+		                            pivotDate = tempPivotDate;
+		                            pivotDate = AdjustCalendarDate(pivotDate, dateUnit, (int)(differenceInDates[unitIndex]));
+		                            isEndDateHit = true;
+		                        }
+		                        else if (tempDaysDiff > 0)
+		                        {
+		                            if (isEndDateHit)
+		                            {
+		                                // This is the closest the pivot can get to the end date for this unit
+		                                break;
+		                            }
+
+		                            // pivotDate is still below the end date
+		                            try
+		                            {
+		                                pivotDate = AdjustCalendarDate(pivotDate, dateUnit, 1);
+		                                differenceInDates[unitIndex] += 1;
+		                            }
+		                            catch (ArgumentException)
+		                            {
+		                                // handling for 31st Dec, 9999 last valid date
+		                                // Do nothing - break out
+		                                break;
+		                            }
+		                        }
+		                    } while (tempDaysDiff != 0); // dates are the same - exit the loop
+
+		                    tempPivotDate = AdjustCalendarDate(tempPivotDate, dateUnit, (int)(differenceInDates[unitIndex]));
+		                    pivotDate = tempPivotDate;
+		                    daysDiff = (uint)GetDifferenceInDays(pivotDate, endDate);
+		                }
+		            }
+		        }
+		    }
+
+		    differenceInDates[3] = daysDiff;
+
+		    difference.year = (int)differenceInDates[0];
+		    difference.month = (int)differenceInDates[1];
+		    difference.week = (int)differenceInDates[2];
+		    difference.day = (int)differenceInDates[3];
+		}
+
+		// Private Methods
+
+		// Gets number of days between the two date time values
+		int GetDifferenceInDays(DateTime date1, DateTime date2)
+		{
+		    // A tick is defined as the number of 100 nanoseconds
+		    long ticksDifference = date2.ToUniversalTime().Ticks - date1.ToUniversalTime().Ticks;
+		    return (int)(ticksDifference / (long)(c_day));
+		}
+
+		// Gets number of Calendar days in the month in which this date falls.
+		// Returns true if successful, false otherwise.
+		bool TryGetCalendarDaysInMonth( DateTime date, out uint daysInMonth)
+		{
+			daysInMonth = 0;
+		    bool result = false;
+		    m_calendar.SetDateTime(date);
+
+		    // NumberOfDaysInThisMonth returns -1 if unknown.
+		    int daysInThisMonth = m_calendar.NumberOfDaysInThisMonth;
+		    if (daysInThisMonth != -1)
+		    {
+		        daysInMonth = (uint)(daysInThisMonth);
+		        result = true;
+		    }
+
+		    return result;
+		}
+
+		// Gets number of Calendar days in the year in which this date falls.
+		// Returns true if successful, false otherwise.
+		bool TryGetCalendarDaysInYear( DateTime date, out uint daysInYear)
+		{
+			daysInYear = 0;
+		    bool result = false;
+		    uint days = 0;
+
+		    m_calendar.SetDateTime(date);
+
+		    // NumberOfMonthsInThisYear returns -1 if unknown.
+		    int monthsInYear = m_calendar.NumberOfMonthsInThisYear;
+		    if (monthsInYear != -1)
+		    {
+		        bool monthResult = true;
+
+		        // Not all years begin with Month 1.
+		        int firstMonthThisYear = m_calendar.FirstMonthInThisYear;
+		        for (int month = 0; month < monthsInYear; month++)
+		        {
+		            m_calendar.Month = firstMonthThisYear + month;
+
+		            // NumberOfDaysInThisMonth returns -1 if unknown.
+		            int daysInMonth = m_calendar.NumberOfDaysInThisMonth;
+		            if (daysInMonth == -1)
+		            {
+		                monthResult = false;
+		                break;
+		            }
+
+		            days += (uint)daysInMonth;
+		        }
+
+		        if (monthResult)
+		        {
+		            daysInYear = days;
+		            result = true;
+		        }
+		    }
+
+		    return result;
+		}
+
+		// Adds/Subtracts certain value for a particular date unit
+		DateTime AdjustCalendarDate(DateTime date, DateUnit dateUnit, int difference)
+		{
+		    m_calendar.SetDateTime(date);
+
+		    // The Japanese Era system can have multiple year partitions within the same year.
+		    // For example, April 30, 2019 is denoted April 30, Heisei 31; May 1, 2019 is denoted as May 1, Reiwa 1.
+		    // The Calendar treats Heisei 31 and Reiwa 1 as separate years, which results in some unexpected behaviors where subtracting a year from Reiwa 1 results in
+		    // a date in Heisei 31. To provide the expected result across era boundaries, we first convert the Japanese era system to a Gregorian system, do date math,
+		    // and then convert back to the Japanese era system. This works because the Japanese era system maintains the same year/month boundaries and durations as
+		    // the Gregorian system and is only different in display value.
+		    var currentCalendarSystem = m_calendar.GetCalendarSystem();
+		    if (currentCalendarSystem == CalendarIdentifiers.Japanese)
+		    {
+		        m_calendar.ChangeCalendarSystem(CalendarIdentifiers.Gregorian);
+		    }
+
+		    switch (dateUnit)
+		    {
+		    case DateUnit.Year:
+		        m_calendar.AddYears(difference);
+		        break;
+		    case DateUnit.Month:
+		        m_calendar.AddMonths(difference);
+		        break;
+		    case DateUnit.Week:
+		        m_calendar.AddWeeks(difference);
+		        break;
+		    }
+
+		    m_calendar.ChangeCalendarSystem(currentCalendarSystem);
+
+		    return m_calendar.GetDateTime().DateTime;
+		}
+	}
+}

src/Calculator.Shared/Common/LocalizationService.cs

@@ -379,7 +379,7 @@ namespace CalculatorApp.Common
         // as configured by running intl.cpl.
         //
         // This helper function creates a DateTimeFormatter with a TwentyFour hour clock
-        DateTimeFormatter GetRegionalSettingsAwareDateTimeFormatter( string format)
+        public static DateTimeFormatter GetRegionalSettingsAwareDateTimeFormatter( string format)
         {
             IEnumerable<String> languageIdentifiers = GetLanguageIdentifiers();
             if (languageIdentifiers == null)
@@ -392,75 +392,39 @@ namespace CalculatorApp.Common
 
         // If successful, returns a formatter that respects the user's regional format settings,
         // as configured by running intl.cpl.
-        DateTimeFormatter GetRegionalSettingsAwareDateTimeFormatter( string format,  string calendarIdentifier,  string clockIdentifier)
+       public static DateTimeFormatter GetRegionalSettingsAwareDateTimeFormatter( string format,  string calendarIdentifier,  string clockIdentifier)
         {
-            // UNO TODO
-            //IIterable<String> languageIdentifiers = GetLanguageIdentifiers();
-            //if (languageIdentifiers == null)
-            //{
-            //    languageIdentifiers = ApplicationLanguages.Languages;
-            //}
+			IEnumerable<string> languageIdentifiers = GetLanguageIdentifiers();
+			if (languageIdentifiers == null)
+			{
+				languageIdentifiers = ApplicationLanguages.Languages;
+			}
 
-            //return  new DateTimeFormatter(format, languageIdentifiers, GlobalizationPerences.HomeGeographicRegion, calendarIdentifier, clockIdentifier);
-
-            throw new NotImplementedException();
+			return new DateTimeFormatter(format, languageIdentifiers, GlobalizationPreferences.HomeGeographicRegion, calendarIdentifier, clockIdentifier);
         }
 
-        public CurrencyFormatter GetRegionalSettingsAwareCurrencyFormatter()
+        public static CurrencyFormatter GetRegionalSettingsAwareCurrencyFormatter()
         {
-            // UNO TODO
-            //string userCurrency =
-            //    (GlobalizationPreferences.Currencies.Size > 0) ? GlobalizationPreferences.Currencies.GetAt(0) : string(DefaultCurrencyCode.data());
+			string userCurrency =
+				(GlobalizationPreferences.Currencies.Count > 0) ? GlobalizationPreferences.Currencies[0] : DefaultCurrencyCode;
 
-            //IIterable<String> languageIdentifiers = GetLanguageIdentifiers();
-            //if (languageIdentifiers == null)
-            //{
-            //    languageIdentifiers = ApplicationLanguages.Languages;
-            //}
+			IEnumerable<string> languageIdentifiers = GetLanguageIdentifiers();
+			if (languageIdentifiers == null)
+			{
+				languageIdentifiers = ApplicationLanguages.Languages;
+			}
 
-            //var currencyFormatter =  new CurrencyFormatter(userCurrency, languageIdentifiers, GlobalizationPerences.HomeGeographicRegion);
+			var currencyFormatter = new CurrencyFormatter(userCurrency, languageIdentifiers, GlobalizationPreferences.HomeGeographicRegion);
 
-            //int fractionDigits = LocalizationSettings.GetInstance().GetCurrencyTrailingDigits();
-            //currencyFormatter.FractionDigits = fractionDigits;
+			int fractionDigits = LocalizationSettings.GetInstance().GetCurrencyTrailingDigits();
+			currencyFormatter.FractionDigits = fractionDigits;
 
-            //return currencyFormatter;
-
-            throw new NotImplementedException();
+			return currencyFormatter;
         }
 
         static IEnumerable<String> GetLanguageIdentifiers()
-        {
-#if !HAS_UNO
-            //char currentLocale[LOCALE_NAME_MAX_LENGTH] = {};
-            //int result = GetUserDefaultLocaleName(currentLocale, LOCALE_NAME_MAX_LENGTH);
-            //if (result != 0)
-            //{
-            //    // GetUserDefaultLocaleName may return an invalid bcp47 language tag with trailing non-BCP47 friendly characters,
-            //    // which if present would start with an underscore, for example sort order
-            //    // (see https://msdn.microsoft.com/en-us/library/windows/desktop/dd373814(v=vs.85).aspx).
-            //    // Therefore, if there is an underscore in the locale name, trim all characters from the underscore onwards.
-            //    WCHAR* underscore = wcschr(currentLocale, '_');
-            //    if (underscore != null)
-            //    {
-            //        *underscore = '\0';
-            //    }
-
-            //    string localestring =  new String(currentLocale);
-            //    // validate if the locale we have is valid
-            //    // otherwise we fallback to the default.
-            //    if (Language.IsWellFormed(localeString))
-            //    {
-            //        var languageList =  new Vector<String>();
-            //        languageList.Append(localeString);
-            //        return languageList;
-            //    }
-            //}
-
-            //return null;
-            yield break;
-#else
-            yield break;
-#endif
+		{
+			return GlobalizationPreferences.Languages;
         }
 
         // Resources for the engine use numbers as keys. It's inconvenient, but also difficult to

src/Calculator.Shared/Common/LocalizationSettings.cs

@@ -128,17 +128,16 @@ namespace CalculatorApp
                     m_digitSymbols[i] = i.ToString(NumberFormatInfo.CurrentInfo)[0];
                 }
 
-                // As CalcEngine only supports the first character of the decimal separator,
-                // Only first character of the decimal separator string is supported.
-                m_decimalSeparator = NumberFormatInfo.CurrentInfo.NumberDecimalSeparator[0];
+				// As CalcEngine only supports the first character of the decimal separator,
+				// Only first character of the decimal separator string is supported.
+				m_decimalSeparator = NumberFormatInfo.CurrentInfo.NumberDecimalSeparator[0];
                 m_numberGroupSeparator = NumberFormatInfo.CurrentInfo.NumberGroupSeparator[0];
                 m_numberGrouping = ""; // UNO TODO https://docs.microsoft.com/en-us/windows/desktop/Intl/locale-sgrouping
                 m_listSeparator = CultureInfo.CurrentCulture.TextInfo.ListSeparator;
                 m_currencyTrailingDigits = NumberFormatInfo.CurrentInfo.CurrencyDecimalDigits;
                 m_currencySymbolPrecedence = ~(NumberFormatInfo.CurrentInfo.CurrencyPositivePattern) & 1;
-
-                m_calendarIdentifier = "";//CultureInfo.CurrentCulture.DateTimeFormat.Calendar.ToString();
-
+				m_resolvedName = CultureInfo.CurrentCulture.Name;
+				m_calendarIdentifier = new Windows.Globalization.Calendar().GetCalendarSystem();
                 m_firstDayOfWeek = (Windows.Globalization.DayOfWeek)CultureInfo.CurrentCulture.DateTimeFormat.FirstDayOfWeek;
 #endif
             }
@@ -155,7 +154,7 @@ namespace CalculatorApp
                 return m_localizationSettings;
             }
 
-            string GetLocaleName()
+			public string GetLocaleName()
             {
                 return m_resolvedName;
             }
@@ -326,7 +325,7 @@ namespace CalculatorApp
                 return m_listSeparator;
             }
 
-            Windows.Globalization.DayOfWeek GetFirstDayOfWeek()
+			public Windows.Globalization.DayOfWeek GetFirstDayOfWeek()
             {
                 return m_firstDayOfWeek;
             }

src/Calculator.Shared/Common/TraceLogger.cs

@@ -0,0 +1,81 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Windows.Globalization;
+using CalculatorApp.Common;
+
+namespace CalculatorApp
+{
+	public class TraceLogger
+	{
+		private static TraceLogger _instance = new TraceLogger();
+		public static TraceLogger GetInstance() => _instance;
+
+
+		public bool GetTraceLoggingProviderEnabled() => false;
+
+		public void LogAppLaunchStart()  {}
+		public void LogAppLaunchComplete()  {}
+		public void LogAppResumeComplete()  {}
+		//public void LogOnAppLaunch(std::wstring_view previousExecutionState)  {}
+		public void LogMemoryClearAll(int i)  {}
+		public void LogBitFlipPaneClicked()  {}
+		public void LogBitFlipUsed()  {}
+		public void LogHistoryBodyOpened()  {}
+		public void LogHistoryItemLoadBegin()  {}
+		public void LogHistoryItemLoadEnd(uint i)  {}
+		public void LogHistoryFlyoutOpenBegin(uint i)  {}
+		public void LogHistoryFlyoutOpenEnd(int i)  {}
+		public void LogCalculatorModeViewed(ViewMode mode, int i)  {}
+		public void LogDateCalculatorModeViewed(ViewMode mode, int i)  {}
+		public void LogConverterModeViewed(ViewMode mode, int i)  {}
+		public void LogModeChangeBegin(ViewMode oldMode, ViewMode newMode, int i)  {}
+		public void LogModeChangeEnd(ViewMode mode, int i)  {}
+		public void LogClearHistory()  {}
+		public void InsertintoMemoryMap(int i, bool b1, bool b2, bool b3)  {}
+		public void UpdateMemoryMap(int i1, int i2, bool b1, bool b2, bool b3)  {}
+		public void DeleteFromMemoryMap(int i1, int i2)  {}
+		public void LogMemoryUsed(int i1, uint i2, bool b1, bool b2, bool b3, uint i4)  {}
+		public void LogMultipleMemoryUsed(uint i1, uint i2)  {}
+		public void LogSingleMemoryUsed(uint i)  {}
+		//public void LogSharedMemoryUsed(std::wstring_view, std::wstring_view, uint i)  {}
+		public void LogMemoryBodyOpened()  {}
+		public void LogMemoryFlyoutOpenBegin(uint i)  {}
+		//public void LogDebug(std::wstring_view debugData)  {}
+		public void LogMemoryFlyoutOpenEnd(uint i)  {}
+		//public void LogInvalidPastedInputOccurred(std::wstring_view reason, ViewMode mode, int ProgrammerNumberBase, int bitLengthType)  {}
+		public void LogValidInputPasted(ViewMode mode)  {}
+		public void UpdateFunctionUsage(int func)  {}
+		public void LogFunctionUsage(int i)  {}
+		public void InitFunctionLogArray()  {}
+		public void LogBitLengthButtonUsed(int windowId)  {}
+		public void LogRadixButtonUsed(int windowId)  {}
+		public void LogAngleButtonUsed(int windowId)  {}
+		public void LogHypButtonUsed(int windowId)  {}
+		public void LogNewWindowCreationBegin(int windowId)  {}
+		public void LogNewWindowCreationEnd(int windowId)  {}
+		//public void LogError(std::wstring_view errorString)  {}
+		public void LogPrelaunchedAppActivatedByUser()  {}
+		public void LogAppPrelaunchedBySystem()  {}
+		//public void UpdateWindowCount(size_t windowCount)  {}
+		public bool UpdateWindowIdLog(int windowId) => true;
+		public void LogMaxWindowCount()  {}
+		public void LogWindowActivated()  {}
+		public void LogWindowLaunched()  {}
+		public void LogUserRequestedRefreshFailed()  {}
+		//public void LogConversionResult(std::wstring_view fromValue, std::wstring_view fromUnit, std::wstring_view toValue, std::wstring_view toUnit)  {}
+		public void LogAboutFlyoutOpened()  {}
+		public void LogNavBarOpened()  {}
+		public void LogViewClosingTelemetry(int i)  {}
+		public void LogCoreWindowWasNull()  {}
+		
+		// Trace methods for Date Calculator usage
+		public void LogDateDifferenceModeUsed(int windowId)  {}
+		public void LogDateAddSubtractModeUsed(int windowId, bool isAddMode)  {}
+		public void LogDateClippedTimeDifferenceFound(Calendar today, DateTime clippedTime)  {}
+		
+		//public void LogStandardException(std::wstring_view functionName, _In_ const std::exception& e)  {}
+		//public void LogWinRTException(std::wstring_view functionName, _In_ winrt::hresult_error const& e)  {}
+		//public void LogPlatformException(std::wstring_view functionName, _In_ Platform::Exception ^ e)  {}
+	}
+}

src/Calculator.Shared/ViewModels/ApplicationViewModel.cs

@@ -35,9 +35,8 @@ namespace CalculatorApp.ViewModel
         private StandardCalculatorViewModel m_CalculatorViewModel;
         public StandardCalculatorViewModel CalculatorViewModel { get => m_CalculatorViewModel; set { m_CalculatorViewModel = value; RaisePropertyChanged("CalculatorViewModel"); } }
 
-        // UNO TODO
-        //private DateCalculatorViewModel m_DateCalcViewModel;
-        //public DateCalculatorViewModel DateCalcViewModel { get => m_DateCalcViewModel; set { m_DateCalcViewModel = value; RaisePropertyChanged("DateCalcViewModel"); } }
+        private DateCalculatorViewModel m_DateCalcViewModel;
+        public DateCalculatorViewModel DateCalcViewModel { get => m_DateCalcViewModel; set { m_DateCalcViewModel = value; RaisePropertyChanged("DateCalcViewModel"); } }
 
 
         // UNO TODO
@@ -160,12 +159,11 @@ namespace CalculatorApp.ViewModel
             else if (NavCategory.IsDateCalculatorViewMode(m_mode))
             {
                 // TraceLogger.GetInstance().LogDateCalculatorModeViewed(m_mode, ApplicationView.GetApplicationViewIdForWindow(CoreWindow.GetForCurrentThread()));
-                // UNO TODO
-                //if (m_DateCalcViewModel == null)
-                //{
-                //    m_DateCalcViewModel = new DateCalculatorViewModel();
-                //}
-            }
+				if (m_DateCalcViewModel == null)
+				{
+					m_DateCalcViewModel = new DateCalculatorViewModel();
+				}
+			}
             else if (NavCategory.IsConverterViewMode(m_mode))
             {
                 // UNO TODO
@@ -200,12 +198,13 @@ namespace CalculatorApp.ViewModel
             //{
             //    ConverterViewModel.OnCopyCommand(parameter);
             //}
-            //else if (NavCategory.IsDateCalculatorViewMode(m_mode))
-            //{
-            //    DateCalcViewModel.OnCopyCommand(parameter);
-            //}
             //else
-            {
+            if (NavCategory.IsDateCalculatorViewMode(m_mode))
+			{
+				DateCalcViewModel.OnCopyCommand(parameter);
+			}
+			else
+			{
                 CalculatorViewModel.OnCopyCommand(parameter);
             }
         }

src/Calculator.Shared/Views/Calculator.xaml.cs

@@ -553,7 +553,7 @@ namespace CalculatorApp
             FullscreenFlyoutClosed();
         }
 
-        void CloseHistoryFlyout()
+        public void CloseHistoryFlyout()
         {
             if (m_fIsHistoryFlyoutOpen)
             {
@@ -561,7 +561,7 @@ namespace CalculatorApp
             }
         }
 
-        void CloseMemoryFlyout()
+        public void CloseMemoryFlyout()
         {
             if (m_fIsMemoryFlyoutOpen)
             {

src/Calculator.Shared/Views/DateCalculator.xaml

@@ -5,11 +5,10 @@
              xmlns:converters="using:CalculatorApp.Converters"
              xmlns:local="using:CalculatorApp.Views"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+			 Loaded="OnLoaded"
              mc:Ignorable="">
     
-             <!-- UNO TODO Loaded="OnLoaded"-->
-
-    <!-- UNO TODO <UserControl.Resources>
+	<UserControl.Resources>
 		<converters:BooleanNegationConverter x:Key="BooleanNegationConverter" />
 		<converters:BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" />
 		<converters:BooleanToVisibilityNegationConverter x:Key="BooleanToVisibilityNegationConverter" />
@@ -441,26 +440,26 @@
 							Value="False" />
 		</Style>
 
-		<MenuFlyout x:Key="ResultsContextMenu"
+		<!--TODO UNO <MenuFlyout x:Key="ResultsContextMenu"
 								x:Name="ResultsContextMenu">
 			<MenuFlyoutItem x:Name="CopyMenuItem"
 											x:Uid="CopyMenuItem"
 											Click="OnCopyMenuItemClicked"
 											Icon="Copy" />
-		</MenuFlyout>
+		</MenuFlyout>-->
 	</UserControl.Resources>
 
 	<Grid x:Name="DateCalculatorGrid"
 				Margin="12,0,12,0"
 				AutomationProperties.LandmarkType="Main">
-		
+
 		<Grid.ColumnDefinitions>
 			<ColumnDefinition x:Name="C0"
 												Width="*" />
 			<ColumnDefinition x:Name="C1"
 												Width="0" />
 		</Grid.ColumnDefinitions>
-		
+
 		<Grid.RowDefinitions>
 			<RowDefinition Height="1*"
 										 MinHeight="{StaticResource HamburgerHeight}"
@@ -500,29 +499,29 @@
 			</VisualStateGroup>
 		</VisualStateManager.VisualStateGroups>
 
-		--><!-- ComboBox for Date Calculation options --><!--
+		<!-- ComboBox for Date Calculation options -->
 		<ComboBox x:Name="DateCalculationOption"
 							x:Uid="DateCalculationOption"
 							Grid.Row="1"
 							Style="{ThemeResource DateCalculation_ComboStyle}"
 							SelectedIndex="0">
-			
+
 			<ComboBoxItem x:Uid="Date_DifferenceOption"
 										MinWidth="276"
 										ContentTemplate="{StaticResource ComboBoxItemContentTemplate}"
 										IsSelected="{Binding IsDateDiffMode, Mode=TwoWay}" />
-			
+
 			<ComboBoxItem x:Uid="Date_AddSubtractOption"
 										MinWidth="276"
 										ContentTemplate="{StaticResource ComboBoxItemContentTemplate}"
 										IsSelected="{Binding IsDateDiffMode, Converter={StaticResource BooleanNegationConverter}, Mode=TwoWay}" />
 		</ComboBox>
 
-		--><!-- Grid to Calculate Difference between Two Dates --><!--
+		<!-- Grid to Calculate Difference between Two Dates -->
 		<Grid x:Name="DateDiffGrid"
 					Grid.Row="2"
 					Visibility="{Binding IsDateDiffMode, Converter={StaticResource BooleanToVisibilityConverter}}">
-			
+
 			<Grid.RowDefinitions>
 				<RowDefinition Height="1*"
 											 MaxHeight="17" />
@@ -543,14 +542,14 @@
 				<RowDefinition Height="Auto" />
 			</Grid.RowDefinitions>
 
-			--><!-- From Date --><!--
+			<!-- From Date -->
 			<TextBlock x:Name="Date_FromLabel"
 								 x:Uid="Date_FromLabel"
 								 Grid.Row="1"
 								 Margin="0,0,0,2"
 								 Foreground="{ThemeResource SystemControlPageTextBaseHighBrush}"
 								 TextWrapping="Wrap" />
-			
+
 			<CalendarDatePicker x:Name="DateDiff_FromDate"
 													Grid.Row="2"
 													Style="{StaticResource DateCalculation_CalendarPickerStyle}"
@@ -559,14 +558,14 @@
 													Closed="CalendarFlyoutClosed"
 													DateChanged="FromDate_DateChanged" />
 
-			--><!-- To Date --><!--
+			<!-- To Date -->
 			<TextBlock x:Name="Date_ToLabel"
 								 x:Uid="Date_ToLabel"
 								 Grid.Row="4"
 								 Margin="0,0,0,2"
 								 Foreground="{ThemeResource SystemControlPageTextBaseHighBrush}"
 								 TextWrapping="Wrap" />
-			
+
 			<CalendarDatePicker x:Name="DateDiff_ToDate"
 													Grid.Row="5"
 													Margin="0,0,0,0"
@@ -576,12 +575,12 @@
 													Closed="CalendarFlyoutClosed"
 													DateChanged="ToDate_DateChanged" />
 
-			--><!-- Difference Result --><!--
+			<!-- Difference Result -->
 			<TextBlock x:Uid="Date_DifferenceLabel"
 								 Grid.Row="7"
 								 Margin="0,0,0,0"
 								 Foreground="{ThemeResource SystemControlPageTextBaseHighBrush}" />
-			
+
 			<TextBlock x:Name="DateDiffAllUnitsResultLabel"
 								 Grid.Row="8"
 								 Style="{ThemeResource SubtitleTextBlockStyle}"
@@ -590,7 +589,7 @@
 								 AutomationProperties.Name="{Binding StrDateDiffResultAutomationName}"
 								 ContextFlyout="{StaticResource ResultsContextMenu}"
 								 Text="{Binding StrDateDiffResult}" />
-			
+
 			<TextBlock Grid.Row="10"
 								 Style="{ThemeResource BaseTextBlockStyle}"
 								 Foreground="{ThemeResource SystemControlPageTextBaseMediumBrush}"
@@ -599,7 +598,7 @@
 								 Visibility="{Binding IsDiffInDays, Converter={StaticResource BooleanToVisibilityNegationConverter}}" />
 		</Grid>
 
-		--><!-- Grid for Add/Subtract Date --><!--
+		<!-- Grid for Add/Subtract Date -->
 		<Grid x:Name="AddSubtractDateGrid"
 					Grid.Row="2"
 					x:DeferLoadStrategy="Lazy"
@@ -624,7 +623,8 @@
 				<RowDefinition Height="Auto" />
 			</Grid.RowDefinitions>
 
-			--><!-- From Date --><!--
+			<!-- From Date -->
+
 			<TextBlock x:Name="AddSubtract_Date_FromLabel"
 								 x:Uid="Date_FromLabel"
 								 Grid.Row="1"
@@ -632,7 +632,7 @@
 								 Style="{ThemeResource BodyTextBlockStyle}"
 								 Foreground="{ThemeResource SystemControlPageTextBaseMediumBrush}"
 								 TextWrapping="Wrap" />
-			
+
 			<CalendarDatePicker x:Name="AddSubtract_FromDate"
 													Grid.Row="2"
 													Margin="0,0,0,0"
@@ -655,7 +655,7 @@
 										 VerticalAlignment="Top"
 										 Checked="AddSubtractOption_Checked"
 										 IsChecked="{Binding IsAddMode, Mode=TwoWay}" />
-				
+
 				<RadioButton x:Name="SubtractOption"
 										 x:Uid="SubtractOption"
 										 Grid.Column="1"
@@ -668,7 +668,8 @@
 
 			</Grid>
 
-			--><!-- Date Offset to be Added/Subtracted --><!--
+			<!-- Date Offset to be Added/Subtracted -->
+
 			<Grid x:Name="DateOffsetGrid"
 						Grid.Row="6">
 
@@ -688,7 +689,7 @@
 									 Margin="0,0,0,6"
 									 Foreground="{ThemeResource SystemControlPageTextBaseMediumBrush}"
 									 TextWrapping="Wrap" />
-				
+
 				<ComboBox x:Name="YearsValue"
 									Grid.Row="1"
 									MinWidth="84"
@@ -697,14 +698,14 @@
 									ItemsSource="{Binding OffsetValues, Mode=OneTime}"
 									SelectedIndex="{Binding YearsOffset, Mode=TwoWay}"
 									SelectionChanged="OffsetValue_Changed" />
-				
+
 				<TextBlock x:Name="MonthsLabel"
 									 x:Uid="MonthsLabel"
 									 Grid.Column="1"
 									 Margin="12,0,12,6"
 									 Foreground="{ThemeResource SystemControlPageTextBaseMediumBrush}"
 									 TextWrapping="Wrap" />
-				
+
 				<ComboBox x:Name="MonthsValue"
 									Grid.Row="1"
 									Grid.Column="1"
@@ -715,14 +716,14 @@
 									ItemsSource="{Binding OffsetValues, Mode=OneTime}"
 									SelectedIndex="{Binding MonthsOffset, Mode=TwoWay}"
 									SelectionChanged="OffsetValue_Changed" />
-				
+
 				<TextBlock x:Name="DaysLabel"
 									 x:Uid="DaysLabel"
 									 Grid.Column="2"
 									 Margin="0,0,0,6"
 									 Foreground="{ThemeResource SystemControlPageTextBaseMediumBrush}"
 									 TextWrapping="Wrap" />
-				
+
 				<ComboBox x:Name="DaysValue"
 									Grid.Row="1"
 									Grid.Column="2"
@@ -734,7 +735,8 @@
 									SelectionChanged="OffsetValue_Changed" />
 			</Grid>
 
-			--><!-- Resulting Date --><!--
+			<!-- Resulting Date -->
+
 			<TextBlock x:Uid="DateLabel"
 								 Grid.Row="8"
 								 Foreground="{ThemeResource SystemControlPageTextBaseMediumBrush}" />
@@ -748,5 +750,5 @@
 								 ContextFlyout="{StaticResource ResultsContextMenu}"
 								 Text="{Binding StrDateResult}" />
 		</Grid>
-	</Grid>-->
+	</Grid>
 </UserControl>

src/Calculator.Shared/Views/DateCalculator.xaml.cs

@@ -1,17 +1,19 @@
-using System;
-using System.Collections.Generic;
-using System.IO;
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
 using System.Linq;
 using System.Runtime.InteropServices.WindowsRuntime;
-using Windows.Foundation;
-using Windows.Foundation.Collections;
+using Windows.Globalization;
+using Windows.Globalization.DateTimeFormatting;
+using Windows.UI.Core;
+using Windows.UI.ViewManagement;
 using Windows.UI.Xaml;
+using Windows.UI.Xaml.Automation;
+using Windows.UI.Xaml.Automation.Peers;
 using Windows.UI.Xaml.Controls;
-using Windows.UI.Xaml.Controls.Primitives;
-using Windows.UI.Xaml.Data;
-using Windows.UI.Xaml.Input;
-using Windows.UI.Xaml.Media;
-using Windows.UI.Xaml.Navigation;
+using CalculatorApp.Common;
+using CalculatorApp.ViewModel;
 
 // The User Control item template is documented at https://go.microsoft.com/fwlink/?LinkId=234236
 
@@ -19,9 +21,207 @@ namespace CalculatorApp
 {
 	public sealed partial class DateCalculator : UserControl
 	{
+		// We choose 2550 as the max year because CalendarDatePicker experiences clipping
+		// issues just after 2558.  We would like 9999 but will need to wait for a platform
+		// fix before we use a higher max year.  This platform issue is tracked by
+		// TODO: MSFT-9273247
+		const int c_maxYear = 2550;
+		const int c_minYear = 1601;
+
 		public DateCalculator()
 		{
 			this.InitializeComponent();
+
+			var localizationSettings = LocalizationSettings.GetInstance();
+
+		    // Set Calendar Identifier
+		    DateDiff_FromDate.CalendarIdentifier = localizationSettings.GetCalendarIdentifier();
+		    DateDiff_ToDate.CalendarIdentifier = localizationSettings.GetCalendarIdentifier();
+
+		    // Setting the FirstDayofWeek
+		    DateDiff_FromDate.FirstDayOfWeek = localizationSettings.GetFirstDayOfWeek();
+		    DateDiff_ToDate.FirstDayOfWeek = localizationSettings.GetFirstDayOfWeek();
+
+		    // Setting the Language explicitly is not required,
+		    // this is a workaround for the bug in the control due to which
+		    // the displayed date is incorrect for non Gregorian Calendar Systems
+		    // The displayed date doesn't honor the shortdate format, on setting the Language the format is refreshed
+		    DateDiff_FromDate.Language = localizationSettings.GetLocaleName();
+		    DateDiff_ToDate.Language = localizationSettings.GetLocaleName();
+
+		    // Set Min and Max Dates according to the Gregorian Calendar(1601 & 9999)
+		    var calendar = new Calendar();
+		    var today = calendar.GetDateTime();
+
+		    calendar.ChangeCalendarSystem(CalendarIdentifiers.Gregorian);
+		    calendar.Day = 1;
+		    calendar.Month = 1;
+		    calendar.Year = c_minYear;
+		    var minYear = calendar.GetDateTime(); // 1st January, 1601
+		    DateDiff_FromDate.MinDate = minYear;
+		    DateDiff_ToDate.MinDate = minYear;
+
+		    calendar.Day = 31;
+		    calendar.Month = 12;
+		    calendar.Year = c_maxYear;
+		    var maxYear = calendar.GetDateTime(); // 31st December, 9878
+		    DateDiff_FromDate.MaxDate = maxYear;
+		    DateDiff_ToDate.MaxDate = maxYear;
+
+		    // Set the PlaceHolderText for CalendarDatePicker
+		    DateTimeFormatter dateTimeFormatter = LocalizationService.GetRegionalSettingsAwareDateTimeFormatter(
+		        "day month year",
+		        localizationSettings.GetCalendarIdentifier(),
+		        ClockIdentifiers.TwentyFourHour); // Clock Identifier is not used
+
+		    DateDiff_FromDate.DateFormat = "day month year";
+		    DateDiff_ToDate.DateFormat = "day month year";
+
+		    var placeholderText = dateTimeFormatter.Format(today);
+
+		    DateDiff_FromDate.PlaceholderText = placeholderText;
+		    DateDiff_ToDate.PlaceholderText = placeholderText;
+
+		    // TODO UNO
+		    // CopyMenuItem.Text = AppResourceProvider.GetInstance().GetResourceString("copyMenuItem");
+		    DateCalculationOption.SelectionChanged += new SelectionChangedEventHandler(DateCalcOption_Changed);
+		}
+
+		void FromDate_DateChanged( CalendarDatePicker sender,  CalendarDatePickerDateChangedEventArgs e)
+		{
+		    if (e.NewDate != null)
+		    {
+		        var dateCalcViewModel = (DateCalculatorViewModel)this.DataContext;
+		        dateCalcViewModel.FromDate = e.NewDate.Value.DateTime;
+		        TraceLogger.GetInstance().LogDateDifferenceModeUsed(ApplicationView.GetApplicationViewIdForWindow(CoreWindow.GetForCurrentThread()));
+		    }
+		    else
+		    {
+		        ReselectCalendarDate(sender, e.OldDate.Value.DateTime);
+		    }
+		}
+
+		void ToDate_DateChanged( CalendarDatePicker sender,  CalendarDatePickerDateChangedEventArgs e)
+		{
+		    if (e.NewDate != null)
+		    {
+		        var dateCalcViewModel = (DateCalculatorViewModel)this.DataContext;
+		        dateCalcViewModel.ToDate = e.NewDate.Value.DateTime;
+		        TraceLogger.GetInstance().LogDateDifferenceModeUsed(ApplicationView.GetApplicationViewIdForWindow(CoreWindow.GetForCurrentThread()));
+		    }
+		    else
+		    {
+		        ReselectCalendarDate(sender, e.OldDate.Value.DateTime);
+		    }
+		}
+
+		void AddSubtract_DateChanged( CalendarDatePicker sender,  CalendarDatePickerDateChangedEventArgs e)
+		{
+		    if (e.NewDate != null)
+		    {
+		        var dateCalcViewModel = (DateCalculatorViewModel)this.DataContext;
+		        dateCalcViewModel.StartDate = e.NewDate.Value.DateTime;
+		        TraceLogger.GetInstance().LogDateAddSubtractModeUsed(
+		            ApplicationView.GetApplicationViewIdForWindow(CoreWindow.GetForCurrentThread()), dateCalcViewModel.IsAddMode);
+		    }
+		    else
+		    {
+		        ReselectCalendarDate(sender, e.OldDate.Value.DateTime);
+		    }
+		}
+
+		void OffsetValue_Changed( object sender,  SelectionChangedEventArgs e)
+		{
+		    var dateCalcViewModel = (DateCalculatorViewModel)this.DataContext;
+		    TraceLogger.GetInstance().LogDateAddSubtractModeUsed(
+		        ApplicationView.GetApplicationViewIdForWindow(CoreWindow.GetForCurrentThread()), dateCalcViewModel.IsAddMode);
+		}
+
+		void OnCopyMenuItemClicked( object sender,  RoutedEventArgs e)
+		{
+			// TODO UNO
+		    //var calcResult = (TextBlock)ResultsContextMenu.Target;
+
+		    //CopyPasteManager.CopyToClipboard(calcResult.Text);
+		}
+
+		void OnLoaded( object sender,  Windows.UI.Xaml.RoutedEventArgs e)
+		{
+		}
+
+		public void CloseCalendarFlyout()
+		{
+		    if (DateDiff_FromDate.IsCalendarOpen)
+		    {
+		        DateDiff_FromDate.IsCalendarOpen = false;
+		    }
+
+		    if (DateDiff_ToDate.IsCalendarOpen)
+		    {
+		        DateDiff_ToDate.IsCalendarOpen = false;
+		    }
+
+		    if ((AddSubtract_FromDate != null) && (AddSubtract_FromDate.IsCalendarOpen))
+		    {
+		        AddSubtract_FromDate.IsCalendarOpen = false;
+		    }
+		}
+
+		public void SetDefaultFocus()
+		{
+		    DateCalculationOption.Focus(FocusState.Programmatic);
+		}
+
+		void DateCalcOption_Changed( object sender,  Windows.UI.Xaml.Controls.SelectionChangedEventArgs e)
+		{
+		    FindName("AddSubtractDateGrid");
+			DateCalculationOption.SelectionChanged -= DateCalcOption_Changed;
+		}
+
+		void AddSubtractDateGrid_Loaded( object sender,  Windows.UI.Xaml.RoutedEventArgs e)
+		{
+		    var localizationSettings = LocalizationSettings.GetInstance();
+
+		    AddSubtract_FromDate.PlaceholderText = DateDiff_FromDate.PlaceholderText;
+		    AddSubtract_FromDate.CalendarIdentifier = localizationSettings.GetCalendarIdentifier();
+		    AddSubtract_FromDate.FirstDayOfWeek = localizationSettings.GetFirstDayOfWeek();
+		    AddSubtract_FromDate.Language = localizationSettings.GetLocaleName();
+
+		    AddSubtract_FromDate.MinDate = DateDiff_FromDate.MinDate;
+		    AddSubtract_FromDate.MaxDate = DateDiff_FromDate.MaxDate;
+		    AddSubtract_FromDate.DateFormat = "day month year";
+		}
+
+		void ReselectCalendarDate( Windows.UI.Xaml.Controls.CalendarDatePicker calendarDatePicker, DateTime dateTime)
+		{
+		    // Reselect the unselected Date
+		    calendarDatePicker.Date = dateTime;
+
+		    // Dismiss the Calendar flyout
+		    calendarDatePicker.IsCalendarOpen = false;
+		}
+
+		void OffsetDropDownClosed( object sender,  object e)
+		{
+		    RaiseLiveRegionChangedAutomationEvent(/* DateDiff mode */ false);
+		}
+
+		void CalendarFlyoutClosed( object sender,  object e)
+		{
+		    var dateCalcViewModel = (DateCalculatorViewModel)this.DataContext;
+		    RaiseLiveRegionChangedAutomationEvent(dateCalcViewModel.IsDateDiffMode);
+		}
+
+		void RaiseLiveRegionChangedAutomationEvent( bool isDateDiffMode)
+		{
+		    TextBlock resultTextBlock = (isDateDiffMode ? DateDiffAllUnitsResultLabel : DateResultLabel);
+		    String automationName = AutomationProperties.GetName(resultTextBlock);
+		    TextBlockAutomationPeer.FromElement(resultTextBlock).RaiseAutomationEvent(AutomationEvents.LiveRegionChanged);
+		}
+
+		void AddSubtractOption_Checked( object sender,  RoutedEventArgs e)
+		{
+		    RaiseLiveRegionChangedAutomationEvent(/* DateDiff mode */ false);
 		}
 	}
 }

src/Calculator.Shared/Views/MainPage.xaml.cs

@@ -284,19 +284,18 @@ namespace CalculatorApp
             {
                 m_calculator.SetDefaultFocus();
             }
+			if (m_dateCalculator != null && m_dateCalculator.Visibility == Visibility.Visible)
+			{
+				m_dateCalculator.SetDefaultFocus();
+			}
+			// UNO TODO
+			//if (m_converter != null && m_converter.Visibility == Visibility.Visible)
+			//{
+			//    m_converter.SetDefaultFocus();
+			//}
+		}
 
-            // UNO TODO
-            //if (m_dateCalculator != null && m_dateCalculator.Visibility == Visibility.Visible)
-            //{
-            //    m_dateCalculator.SetDefaultFocus();
-            //}
-            //if (m_converter != null && m_converter.Visibility == Visibility.Visible)
-            //{
-            //    m_converter.SetDefaultFocus();
-            //}
-        }
-
-        void EnsureCalculator()
+		void EnsureCalculator()
         {
             if (m_calculator == null)
             {
@@ -336,23 +335,22 @@ namespace CalculatorApp
 
         void EnsureDateCalculator()
         {
-            // UNO TODO
-            //if (m_dateCalculator == null)
-            //{
-            //    // delay loading converter
-            //    m_dateCalculator = new DateCalculator();
-            //    m_dateCalculator.Name = "dateCalculator";
-            //    m_dateCalculator.DataContext = m_model.DateCalcViewModel;
+			if (m_dateCalculator == null)
+			{
+				// delay loading converter
+				m_dateCalculator = new DateCalculator();
+				m_dateCalculator.Name = "dateCalculator";
+				m_dateCalculator.DataContext = m_model.DateCalcViewModel;
 
-            //    DateCalcHolder.Child = m_dateCalculator;
-            //}
+				DateCalcHolder.Child = m_dateCalculator;
+			}
 
-            //if (m_calculator != null)
-            //{
-            //    m_calculator.CloseHistoryFlyout();
-            //    m_calculator.CloseMemoryFlyout();
-            //}
-        }
+			if (m_calculator != null)
+			{
+				m_calculator.CloseHistoryFlyout();
+				m_calculator.CloseMemoryFlyout();
+			}
+		}
 
         void EnsureConverter()
         {