1 files changed, 76 insertions, 0 deletions
diff --git a/Xamarin.Forms.Platform.WinRT/FormsDatePicker.cs b/Xamarin.Forms.Platform.WinRT/FormsDatePicker.cs
new file mode 100644
index 00000000..44127423
--- /dev/null
+++ b/Xamarin.Forms.Platform.WinRT/FormsDatePicker.cs
@@ -0,0 +1,76 @@
+using System;
+using Windows.UI.Core;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+
+#if WINDOWS_UWP
+
+namespace Xamarin.Forms.Platform.UWP
+#else
+
+namespace Xamarin.Forms.Platform.WinRT
+#endif
+{
+	public class FormsDatePicker : Windows.UI.Xaml.Controls.DatePicker
+	{
+		public FormsDatePicker()
+		{
+			if (Device.Idiom == TargetIdiom.Desktop || Device.Idiom == TargetIdiom.Tablet)
+			{
+				Loaded += (sender, args) => { Window.Current.Activated += WindowOnActivated; };
+				Unloaded += (sender, args) => { Window.Current.Activated -= WindowOnActivated; };
+			}
+		}
+
+		public event EventHandler<EventArgs> ForceInvalidate;
+
+		protected override void OnApplyTemplate()
+		{
+			base.OnApplyTemplate();
+
+			if (Device.Idiom == TargetIdiom.Desktop || Device.Idiom == TargetIdiom.Tablet)
+			{
+				// Look for the combo boxes which make up a DatePicker on Windows 8.1
+				// So we can hook into their closed events and invalidate them if necessary
+
+				var dayPicker = GetTemplateChild("DayPicker") as ComboBox;
+				if (dayPicker != null)
+				{
+					dayPicker.DropDownClosed += PickerOnDropDownClosed;
+				}
+
+				var monthPicker = GetTemplateChild("MonthPicker") as ComboBox;
+				if (monthPicker != null)
+				{
+					monthPicker.DropDownClosed += PickerOnDropDownClosed;
+				}
+
+				var yearPicker = GetTemplateChild("YearPicker") as ComboBox;
+				if (yearPicker != null)
+				{
+					yearPicker.DropDownClosed += PickerOnDropDownClosed;
+				}
+			}
+		}
+
+		void PickerOnDropDownClosed(object sender, object o)
+		{
+			// If the DatePicker is in a TableView or ListView and the user 
+			// opens one of the dropdowns but does not actually change the value,
+			// when the dropdown closes, the selected value will go blank
+			// To fix this, we have to invalidate the control
+			// This only applies to Windows 8.1
+			ForceInvalidate?.Invoke(this, EventArgs.Empty);
+		}
+
+		void WindowOnActivated(object sender, WindowActivatedEventArgs windowActivatedEventArgs)
+		{
+			// If the DatePicker is in a TableView or ListView, when the application loses and then regains focus
+			// the TextBlock/ComboBox controls (UWP and 8.1, respectively) which display its selected value
+			// will go blank.
+			// To fix this, we have to signal the renderer to invalidate if
+			// Window.Activated occurs.
+			ForceInvalidate?.Invoke(this, EventArgs.Empty);
+		}
+	}
+}
+\ No newline at end of file