Native Bindings (#278)

* [C, I, A, W] Support Native Bindings

* fix tabs

6 files changed, 178 insertions, 1 deletions

diff --git a/Xamarin.Forms.Platform.WinRT/FrameworkElementExtensions.cs b/Xamarin.Forms.Platform.WinRT/FrameworkElementExtensions.cs
index eb040e02..f94f3d62 100644
--- a/Xamarin.Forms.Platform.WinRT/FrameworkElementExtensions.cs
+++ b/Xamarin.Forms.Platform.WinRT/FrameworkElementExtensions.cs
@@ -128,5 +128,21 @@ namespace Xamarin.Forms.Platform.WinRT
 
 			return foregroundProperty;
 		}
+
+		internal static IEnumerable<T> GetChildren<T>(this DependencyObject parent) where T : DependencyObject
+		{
+			int myChildrenCount = VisualTreeHelper.GetChildrenCount(parent);
+			for (int i = 0; i < myChildrenCount; i++)
+			{
+				var child = VisualTreeHelper.GetChild(parent, i);
+				if (child is T)
+					yield return child as T;
+				else
+				{
+					foreach (var subChild in child.GetChildren<T>())
+						yield return subChild;
+				}
+			}
+		}
 	}
 }
\ No newline at end of file
diff --git a/Xamarin.Forms.Platform.WinRT/NativeBindingExtensions.cs b/Xamarin.Forms.Platform.WinRT/NativeBindingExtensions.cs
new file mode 100644
index 00000000..cc88c87e
--- /dev/null
+++ b/Xamarin.Forms.Platform.WinRT/NativeBindingExtensions.cs
@@ -0,0 +1,58 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using Windows.UI.Xaml;
+using static System.String;
+#if WINDOWS_UWP
+
+namespace Xamarin.Forms.Platform.UWP
+#else
+
+namespace Xamarin.Forms.Platform.WinRT
+#endif
+{
+	public static class NativeBindingExtensions
+	{
+		public static void SetBinding(this FrameworkElement view, string propertyName, BindingBase bindingBase, string updateSourceEventName = null)
+		{
+			var binding = bindingBase as Binding;
+			updateSourceEventName = updateSourceEventName ?? binding?.UpdateSourceEventName;
+
+			if (IsNullOrEmpty(updateSourceEventName))
+			{
+				NativePropertyListener nativePropertyListener = null;
+				if (bindingBase.Mode == BindingMode.TwoWay)
+					nativePropertyListener = new NativePropertyListener(view, propertyName);
+
+				NativeBindingHelpers.SetBinding(view, propertyName, bindingBase, nativePropertyListener as INotifyPropertyChanged);
+				return;
+			}
+
+			NativeEventWrapper eventE = null;
+			if (binding.Mode == BindingMode.TwoWay && !(view is INotifyPropertyChanged))
+				eventE = new NativeEventWrapper(view, propertyName, updateSourceEventName);
+
+			NativeBindingHelpers.SetBinding(view, propertyName, binding, eventE);
+		}
+
+		public static void SetBinding(this FrameworkElement view, BindableProperty targetProperty, BindingBase binding)
+		{
+			NativeBindingHelpers.SetBinding(view, targetProperty, binding);
+		}
+
+		public static void SetValue(this FrameworkElement target, BindableProperty targetProperty, object value)
+		{
+			NativeBindingHelpers.SetValue(target, targetProperty, value);
+		}
+
+		public static void SetBindingContext(this FrameworkElement target, object bindingContext, Func<FrameworkElement, IEnumerable<FrameworkElement>> getChildren = null)
+		{
+			NativeBindingHelpers.SetBindingContext(target, bindingContext, getChildren);
+		}
+
+		internal static void TransferbindablePropertiesToWrapper(this FrameworkElement target, View wrapper)
+		{
+			NativeBindingHelpers.TransferBindablePropertiesToWrapper(target, wrapper);
+		}
+	}
+}
\ No newline at end of file
diff --git a/Xamarin.Forms.Platform.WinRT/NativeEventWrapper.cs b/Xamarin.Forms.Platform.WinRT/NativeEventWrapper.cs
new file mode 100644
index 00000000..e28ca0eb
--- /dev/null
+++ b/Xamarin.Forms.Platform.WinRT/NativeEventWrapper.cs
@@ -0,0 +1,45 @@
+using System;
+using System.ComponentModel;
+using System.Linq;
+using System.Reflection;
+using System.Runtime.InteropServices.WindowsRuntime;
+using Windows.UI.Xaml;
+
+#if WINDOWS_UWP
+namespace Xamarin.Forms.Platform.UWP
+#else
+namespace Xamarin.Forms.Platform.WinRT
+#endif
+{
+	class NativeEventWrapper : INotifyPropertyChanged
+	{
+		static string TargetProperty { get; set; }
+		static readonly MethodInfo s_handlerinfo = typeof(NativeEventWrapper).GetRuntimeMethods().Single(mi => mi.Name == nameof(OnPropertyChanged) && mi.IsPublic == false);
+
+		public NativeEventWrapper(object target, string targetProperty, string updateSourceEventName)
+		{
+			TargetProperty = targetProperty;
+			try {
+				var updateSourceEvent = target.GetType().GetRuntimeEvent(updateSourceEventName);
+				MethodInfo addMethod = updateSourceEvent.AddMethod;
+				MethodInfo removeMethod = updateSourceEvent.RemoveMethod;
+				ParameterInfo[] addParameters = addMethod.GetParameters();
+				Type delegateType = addParameters[0].ParameterType;
+				var handlerDelegate = s_handlerinfo.CreateDelegate(delegateType, this);
+				Func<object, EventRegistrationToken> add = a => (EventRegistrationToken)addMethod.Invoke(target, new object[] { handlerDelegate });
+				Action<EventRegistrationToken> remove = t => removeMethod.Invoke(target, new object[] { t });
+				WindowsRuntimeMarshal.AddEventHandler(add, remove, s_handlerinfo);
+			}
+			catch (Exception) {
+				Log.Warning(nameof(NativeEventWrapper), "Can not attach NativeEventWrapper.");
+			}
+		}
+
+		void OnPropertyChanged(object sender, RoutedEventArgs e)
+		{
+			PropertyChanged?.Invoke(sender, new PropertyChangedEventArgs(TargetProperty));
+		}
+
+		public event PropertyChangedEventHandler PropertyChanged;
+	}
+}
diff --git a/Xamarin.Forms.Platform.WinRT/NativePropertyListener.cs b/Xamarin.Forms.Platform.WinRT/NativePropertyListener.cs
new file mode 100644
index 00000000..5a1b294c
--- /dev/null
+++ b/Xamarin.Forms.Platform.WinRT/NativePropertyListener.cs
@@ -0,0 +1,47 @@
+using System;
+using System.ComponentModel;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Data;
+
+#if WINDOWS_UWP
+namespace Xamarin.Forms.Platform.UWP
+#else
+namespace Xamarin.Forms.Platform.WinRT
+#endif
+{
+	class NativePropertyListener : DependencyObject, INotifyPropertyChanged
+	{
+		readonly DependencyObject _target;
+		readonly string _targetProperty;
+
+		public static readonly DependencyProperty TargetPropertyValueProperty = DependencyProperty.Register(nameof(TargetPropertyValue), typeof(object), typeof(NativePropertyListener), new PropertyMetadata(null, OnNativePropertyChanged));
+
+		public event PropertyChangedEventHandler PropertyChanged;
+
+		public NativePropertyListener(DependencyObject target, string propertyName)
+		{
+			_target = target;
+			_targetProperty = propertyName;
+			BindingOperations.SetBinding(this, TargetPropertyValueProperty, new Windows.UI.Xaml.Data.Binding() { Source = _target, Path = new PropertyPath(_targetProperty), Mode = Windows.UI.Xaml.Data.BindingMode.OneWay });
+		}
+
+		public void Dispose()
+		{
+			ClearValue(TargetPropertyValueProperty);
+		}
+
+		public object TargetPropertyValue
+		{
+			get
+			{
+				return GetValue(TargetPropertyValueProperty);
+			}
+		}
+
+		static void OnNativePropertyChanged(object sender, DependencyPropertyChangedEventArgs args)
+		{
+			NativePropertyListener source = (NativePropertyListener)sender;
+			source?.PropertyChanged?.Invoke(source._target, new PropertyChangedEventArgs(source._targetProperty));
+		}		
+	}
+}
\ No newline at end of file
diff --git a/Xamarin.Forms.Platform.WinRT/NativeViewWrapper.cs b/Xamarin.Forms.Platform.WinRT/NativeViewWrapper.cs
index 824f0eed..22cca62e 100644
--- a/Xamarin.Forms.Platform.WinRT/NativeViewWrapper.cs
+++ b/Xamarin.Forms.Platform.WinRT/NativeViewWrapper.cs
@@ -1,4 +1,5 @@
 using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
 
 #if WINDOWS_UWP
 
@@ -17,6 +18,7 @@ namespace Xamarin.Forms.Platform.WinRT
 			ArrangeOverrideDelegate = arrangeOverrideDelegate;
 			MeasureOverrideDelegate = measureOverrideDelegate;
 			NativeElement = nativeElement;
+			nativeElement.TransferbindablePropertiesToWrapper(this);
 		}
 
 		public ArrangeOverrideDelegate ArrangeOverrideDelegate { get; set; }
@@ -26,5 +28,11 @@ namespace Xamarin.Forms.Platform.WinRT
 		public MeasureOverrideDelegate MeasureOverrideDelegate { get; set; }
 
 		public FrameworkElement NativeElement { get; }
+
+		protected override void OnBindingContextChanged()
+		{
+			NativeElement.SetBindingContext(BindingContext,  nv =>  nv.GetChildren<FrameworkElement>());
+			base.OnBindingContextChanged();
+		}
 	}
 }
\ No newline at end of file
diff --git a/Xamarin.Forms.Platform.WinRT/Xamarin.Forms.Platform.WinRT.csproj b/Xamarin.Forms.Platform.WinRT/Xamarin.Forms.Platform.WinRT.csproj
index fd73aae0..ea456c00 100644
--- a/Xamarin.Forms.Platform.WinRT/Xamarin.Forms.Platform.WinRT.csproj
+++ b/Xamarin.Forms.Platform.WinRT/Xamarin.Forms.Platform.WinRT.csproj
@@ -69,7 +69,10 @@
     <Compile Include="PlatformConfigurationExtensions.cs" />
   </ItemGroup>
   <ItemGroup Condition=" '$(OS)' != 'Unix' ">
-	<Compile Include="BrushHelpers.cs" />
+	  <Compile Include="BrushHelpers.cs" />
+    <Compile Include="NativeBindingExtensions.cs" />
+    <Compile Include="NativeEventWrapper.cs" />
+    <Compile Include="NativePropertyListener.cs" />
     <Compile Include="NativeViewWrapper.cs" />
     <Compile Include="NativeViewWrapperRenderer.cs" />
     <Compile Include="ViewExtensions.cs" />