1 files changed, 82 insertions, 0 deletions
diff --git a/Xamarin.Forms.Platform.WinRT/BackgroundTracker.cs b/Xamarin.Forms.Platform.WinRT/BackgroundTracker.cs
new file mode 100644
index 00000000..c7474015
--- /dev/null
+++ b/Xamarin.Forms.Platform.WinRT/BackgroundTracker.cs
@@ -0,0 +1,82 @@
+using System;
+using System.ComponentModel;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Media;
+using Windows.UI.Xaml.Media.Imaging;
+
+#if WINDOWS_UWP
+
+namespace Xamarin.Forms.Platform.UWP
+#else
+
+namespace Xamarin.Forms.Platform.WinRT
+#endif
+{
+	internal sealed class BackgroundTracker<T> : VisualElementTracker<Page, T> where T : FrameworkElement
+	{
+		readonly DependencyProperty _backgroundProperty;
+		bool _backgroundNeedsUpdate = true;
+
+		public BackgroundTracker(DependencyProperty backgroundProperty)
+		{
+			if (backgroundProperty == null)
+				throw new ArgumentNullException("backgroundProperty");
+
+			_backgroundProperty = backgroundProperty;
+		}
+
+		protected override void OnPropertyChanged(object sender, PropertyChangedEventArgs e)
+		{
+			if (e.PropertyName == VisualElement.BackgroundColorProperty.PropertyName || e.PropertyName == Page.BackgroundImageProperty.PropertyName)
+			{
+				UpdateBackground();
+			}
+
+			base.OnPropertyChanged(sender, e);
+		}
+
+		protected override void UpdateNativeControl()
+		{
+			base.UpdateNativeControl();
+
+			if (_backgroundNeedsUpdate)
+				UpdateBackground();
+		}
+
+		void UpdateBackground()
+		{
+			if (Element == null)
+				return;
+
+			FrameworkElement element = Control ?? Container;
+			if (element == null)
+				return;
+
+			string backgroundImage = Element.BackgroundImage;
+			if (backgroundImage != null)
+			{
+				Uri uri;
+				if (!Uri.TryCreate(backgroundImage, UriKind.RelativeOrAbsolute, out uri) || !uri.IsAbsoluteUri)
+					uri = new Uri("ms-appx:///" + backgroundImage);
+
+				element.SetValue(_backgroundProperty, new ImageBrush { ImageSource = new BitmapImage(uri) });
+			}
+			else
+			{
+				Color backgroundColor = Element.BackgroundColor;
+				if (!backgroundColor.IsDefault)
+				{
+					element.SetValue(_backgroundProperty, backgroundColor.ToBrush());
+				}
+				else
+				{
+					object localBackground = element.ReadLocalValue(_backgroundProperty);
+					if (localBackground != null && localBackground != DependencyProperty.UnsetValue)
+						element.ClearValue(_backgroundProperty);
+				}
+			}
+
+			_backgroundNeedsUpdate = false;
+		}
+	}
+}
+\ No newline at end of file