[UWP] Fixed inconsistency on UWP's DatePicker and the other OS's. (#1183)

* [UWP] Fixed inconsistency on UWP's DatePicker and the other OS's.

* [UWP] bz60001 Test case.

* * [UWP] Fixed inconsistency on UWP's DatePicker and the other OS's. (Build fix)

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Bugzilla60001.cs

@@ -0,0 +1,34 @@
+using Xamarin.Forms.CustomAttributes;
+using Xamarin.Forms.Internals;
+using System;
+
+#if UITEST
+using Xamarin.UITest;
+using NUnit.Framework;
+#endif
+
+// Apply the default category of "Issues" to all of the tests in this assembly
+// We use this as a catch-all for tests which haven't been individually categorized
+#if UITEST
+[assembly: NUnit.Framework.Category("Issues")]
+#endif
+
+namespace Xamarin.Forms.Controls.Issues
+{
+	[Preserve(AllMembers = true)]
+	[Issue(IssueTracker.Bugzilla, 60001, "[UWP] Inconsistency with DatePicker ", PlatformAffected.UWP)]
+	public class Bugzilla60001 : TestContentPage // or TestMasterDetailPage, etc ...
+	{
+		protected override void Init()
+		{
+			StackLayout layout = new StackLayout() { Orientation = StackOrientation.Vertical };
+			DatePicker picker = new DatePicker();
+			picker.Date = new DateTime(2017, 10, 7, 0, 0, 0, DateTimeKind.Utc);
+			Label label = new Label() { Text = "On Droid this will show as 10/7/2017, on UWP it will show as 10/06/2017.  Local TimeZone for this test was EDT.", LineBreakMode = LineBreakMode.WordWrap };
+			layout.Children.Add(picker);
+			layout.Children.Add(label);
+			// Initialize ui here instead of ctor
+			Content = layout;
+		}
+	}
+}

Xamarin.Forms.Controls.Issues/Xamarin.Forms.Controls.Issues.Shared/Xamarin.Forms.Controls.Issues.Shared.projitems

@@ -234,6 +234,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla59248.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla59457.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla59580.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Bugzilla60001.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla60056.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla60122.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Bugzilla59863_0.cs" />

Xamarin.Forms.Platform.UAP/DatePickerRenderer.cs

@@ -98,17 +98,20 @@ namespace Xamarin.Forms.Platform.UWP
 
 		void OnControlDateChanged(object sender, DatePickerValueChangedEventArgs e)
 		{
-			Element.Date = e.NewDate.Date;
-			DateTime currentDate = Element.Date;
-			if (currentDate != e.NewDate.Date) // Match coerced value
-				UpdateDate(currentDate);
+			if (Element == null)
+				return;
 
-			((IVisualElementController)Element).InvalidateMeasure(InvalidationTrigger.SizeRequestChanged);
+			if (Element.Date.CompareTo(e.NewDate.Date) != 0)
+			{
+				Element.Date = e.NewDate.Date;
+				((IVisualElementController)Element).InvalidateMeasure(InvalidationTrigger.SizeRequestChanged);
+			}
 		}
 
 		void UpdateDate(DateTime date)
 		{
-			Control.Date = date;
+			if (Control != null)
+				Control.Date = new DateTimeOffset(new DateTime(date.Ticks, DateTimeKind.Unspecified));
 		}
 
 		void UpdateFlowDirection()
@@ -151,8 +154,8 @@ namespace Xamarin.Forms.Platform.UWP
 
 		void UpdateMaximumDate()
 		{
-			DateTime maxdate = Element.MaximumDate;
-			Control.MaxYear = new DateTimeOffset(maxdate);
+			if (Element != null && Control != null)
+				Control.MaxYear = new DateTimeOffset(new DateTime(Element.MaximumDate.Ticks, DateTimeKind.Unspecified));			
 		}
 
 		void UpdateMinimumDate()
@@ -161,7 +164,8 @@ namespace Xamarin.Forms.Platform.UWP
 
 			try
 			{
-				Control.MinYear = new DateTimeOffset(mindate);
+				if (Element != null && Control != null)
+					Control.MinYear = new DateTimeOffset(new DateTime(Element.MinimumDate.Ticks, DateTimeKind.Unspecified));
 			}
 			catch (ArgumentOutOfRangeException)
 			{