Implement Date property in WinUI DatePickerHandler

src/Compatibility/Core/src/Windows/DatePickerRenderer.cs

@@ -143,6 +143,7 @@ namespace Microsoft.Maui.Controls.Compatibility.Platform.UWP
 			return String.IsNullOrWhiteSpace(Element.Format) || Element.Format.Equals("d");
 		}
 
+		[PortHandler]
 		void UpdateDate(DateTime date)
 		{
 			if (Control != null)
@@ -153,6 +154,7 @@ namespace Microsoft.Maui.Controls.Compatibility.Platform.UWP
 			UpdateYear();
 		}
 
+		[PortHandler]
 		void UpdateMonth()
 		{
 			Control.MonthVisible = true;
@@ -178,6 +180,7 @@ namespace Microsoft.Maui.Controls.Compatibility.Platform.UWP
 			}
 		}
 
+		[PortHandler]
 		void UpdateDay()
 		{
 			Control.DayVisible = true;
@@ -203,6 +206,7 @@ namespace Microsoft.Maui.Controls.Compatibility.Platform.UWP
 			}
 		}
 
+		[PortHandler]
 		void UpdateYear()
 		{
 			Control.YearVisible = true;

src/Core/src/Handlers/DatePicker/DatePickerHandler.Windows.cs

@@ -10,8 +10,10 @@ namespace Microsoft.Maui.Handlers
 		[MissingMapper]
 		public static void MapFormat(DatePickerHandler handler, IDatePicker datePicker) { }
 
-		[MissingMapper]
-		public static void MapDate(DatePickerHandler handler, IDatePicker datePicker) { }
+		public static void MapDate(DatePickerHandler handler, IDatePicker datePicker)
+		{
+			handler.NativeView?.UpdateDate(datePicker);
+		}
 
 		[MissingMapper]
 		public static void MapMinimumDate(DatePickerHandler handler, IDatePicker datePicker) { }

src/Core/src/Platform/Windows/DatePickerExtensions.cs

@@ -0,0 +1,95 @@
+using System;
+using System.Linq;
+using Microsoft.UI.Xaml.Controls;
+
+namespace Microsoft.Maui
+{
+	public static class DatePickerExtensions
+	{
+		public static void UpdateDate(this DatePicker nativeDatePicker, IDatePicker datePicker)
+		{
+			var date = datePicker.Date;
+			nativeDatePicker.Date = new DateTimeOffset(new DateTime(date.Ticks, DateTimeKind.Unspecified));
+
+			nativeDatePicker.UpdateDay(datePicker);
+			nativeDatePicker.UpdateMonth(datePicker);
+			nativeDatePicker.UpdateYear(datePicker);
+		}
+
+		internal static void UpdateDay(this DatePicker nativeDatePicker, IDatePicker datePicker)
+		{
+			nativeDatePicker.DayVisible = true;
+
+			if (string.IsNullOrWhiteSpace(datePicker.Format) || datePicker.Format.Equals("d"))
+			{
+				nativeDatePicker.DayFormat = "day";
+			}
+			else if (datePicker.Format.Equals("D"))
+			{
+				nativeDatePicker.DayFormat = "dayofweek.full";
+			}
+			else
+			{
+				var day = datePicker.Format.Count(x => x == 'd');
+				if (day == 0)
+					nativeDatePicker.DayVisible = false;
+				else if (day == 3)
+					nativeDatePicker.DayFormat = "day dayofweek.abbreviated";
+				else if (day == 4)
+					nativeDatePicker.DayFormat = "dayofweek.full";
+				else
+					nativeDatePicker.DayFormat = "day";
+			}
+		}
+
+		internal static void UpdateMonth(this DatePicker nativeDatePicker, IDatePicker datePicker)
+		{
+			nativeDatePicker.MonthVisible = true;
+
+			if (string.IsNullOrWhiteSpace(datePicker.Format) || datePicker.Format.Equals("d"))
+			{
+				nativeDatePicker.MonthFormat = "month";
+			}
+			else if (datePicker.Format.Equals("D"))
+			{
+				nativeDatePicker.MonthFormat = "month.full";
+			}
+			else
+			{
+				var month = datePicker.Format.Count(x => x == 'M');
+				if (month == 0)
+					nativeDatePicker.MonthVisible = false;
+				else if (month <= 2)
+					nativeDatePicker.MonthFormat = "month.numeric";
+				else if (month == 3)
+					nativeDatePicker.MonthFormat = "month.abbreviated";
+				else
+					nativeDatePicker.MonthFormat = "month.full";
+			}
+		}
+
+		internal static void UpdateYear(this DatePicker nativeDatePicker, IDatePicker datePicker)
+		{
+			nativeDatePicker.YearVisible = true;
+
+			if (string.IsNullOrWhiteSpace(datePicker.Format) || datePicker.Format.Equals("d"))
+			{
+				nativeDatePicker.YearFormat = "year";
+			}
+			else if (datePicker.Format.Equals("D"))
+			{
+				nativeDatePicker.YearFormat = "year.full";
+			}
+			else
+			{
+				var year = datePicker.Format.Count(x => x == 'y');
+				if (year == 0)
+					nativeDatePicker.YearVisible = false;
+				else if (year <= 2)
+					nativeDatePicker.YearFormat = "year.abbreviated";
+				else
+					nativeDatePicker.YearFormat = "year.full";
+			}
+		}
+	}
+}