Implemented colored refresh indicator for ListView pull-to-refresh (#2961)

* Implemented colored spinner for ListView pull-to-refresh

* Added back default spinner color

* Renamed away from "spinner" and did some default value magic

Color.Default reinstated, but also added the default black color in the iOS `UpdateRefreshControlColor` method. Seeing this also happens for the seperator color this is something that is necessary. If not, the spinner is invisible.

* Implemented default color on iOS and right property name on Android

For iOS, when the new `RefreshControlColor` has the default color, the `TintColor` for iOS is set to null, causing the color to be the default one.

Forgot to refactor the new name in the Android renderer, whoops

* Reinstated coloring on listview gallry page

* Implemented colored spinner for ListView pull-to-refresh

* Added back default spinner color

* Renamed away from "spinner" and did some default value magic

Color.Default reinstated, but also added the default black color in the iOS `UpdateRefreshControlColor` method. Seeing this also happens for the seperator color this is something that is necessary. If not, the spinner is invisible.

* Implemented default color on iOS and right property name on Android

For iOS, when the new `RefreshControlColor` has the default color, the `TintColor` for iOS is set to null, causing the color to be the default one.

Forgot to refactor the new name in the Android renderer, whoops

* Reinstated coloring on listview gallry page

* Added documentation for new property

* Fixed merge boo-boos

Xamarin.Forms.Controls/CoreGalleryPages/ListViewCoreGalleryPage.cs

@@ -4,8 +4,8 @@ using System.Collections.ObjectModel;
 using System.ComponentModel;
 using System.Linq;
 using System.Runtime.CompilerServices;
+using System.Threading.Tasks;
 using Xamarin.Forms.CustomAttributes;
-using System.Threading;
 using Xamarin.Forms.Internals;
 
 using Xamarin.Forms.PlatformConfiguration;
@@ -267,6 +267,16 @@ namespace Xamarin.Forms.Controls
 			fastScrollItemContainer.View.On<Android>().SetIsFastScrollEnabled(true);
 			fastScrollItemContainer.View.ItemsSource = viewModel.CategorizedEmployees;
 
+			var refreshControlColorContainer = new ViewContainer<ListView>(Test.ListView.RefreshControlColor, new ListView());
+			InitializeElement(refreshControlColorContainer.View);
+			refreshControlColorContainer.View.RefreshControlColor = Color.Red;
+			refreshControlColorContainer.View.IsPullToRefreshEnabled = true;
+			refreshControlColorContainer.View.Refreshing += async (object sender, EventArgs e) => {
+				await Task.Delay(2000);
+				refreshControlColorContainer.View.IsRefreshing = false;
+			};
+			refreshControlColorContainer.View.ItemsSource = viewModel.Employees;
+
 			var scrollbarVisibilityContainer = new ViewContainer<ListView>(Test.ListView.ScrollBarVisibility, new ListView());
 			InitializeElement(scrollbarVisibilityContainer.View);
 			scrollbarVisibilityContainer.View.HorizontalScrollBarVisibility = ScrollBarVisibility.Never;
@@ -287,6 +297,7 @@ namespace Xamarin.Forms.Controls
 			Add(rowHeightContainer);
 			Add(selectedItemContainer);
 			Add(fastScrollItemContainer);
+			Add(refreshControlColorContainer);
 			Add(scrollbarVisibilityContainer);
 		}
 	}

Xamarin.Forms.Core/ListView.cs

@@ -46,6 +46,8 @@ namespace Xamarin.Forms
 
 		public static readonly BindableProperty SeparatorColorProperty = BindableProperty.Create("SeparatorColor", typeof(Color), typeof(ListView), Color.Default);
 
+		public static readonly BindableProperty RefreshControlColorProperty = BindableProperty.Create(nameof(RefreshControlColor), typeof(Color), typeof(ListView), Color.Default);
+    
 		public static readonly BindableProperty HorizontalScrollBarVisibilityProperty = BindableProperty.Create(nameof(HorizontalScrollBarVisibility), typeof(ScrollBarVisibility), typeof(ListView), ScrollBarVisibility.Default);
 
 		public static readonly BindableProperty VerticalScrollBarVisibilityProperty = BindableProperty.Create(nameof(VerticalScrollBarVisibility), typeof(ScrollBarVisibility), typeof(ListView), ScrollBarVisibility.Default);
@@ -223,6 +225,12 @@ namespace Xamarin.Forms
 			set { SetValue(SeparatorColorProperty, value); }
 		}
 
+		public Color RefreshControlColor
+		{
+			get { return (Color)GetValue(RefreshControlColorProperty); }
+			set { SetValue(RefreshControlColorProperty, value); }
+		}
+
 		public SeparatorVisibility SeparatorVisibility
 		{
 			get { return (SeparatorVisibility)GetValue(SeparatorVisibilityProperty); }

Xamarin.Forms.CustomAttributes/TestAttributes.cs

@@ -431,6 +431,7 @@ namespace Xamarin.Forms.CustomAttributes
 			GroupShortNameBinding,
 			ScrollTo,
 			FastScroll,
+			RefreshControlColor,
 			ScrollBarVisibility
 		}
 

Xamarin.Forms.Platform.Android/Renderers/ListViewRenderer.cs

@@ -178,6 +178,7 @@ namespace Xamarin.Forms.Platform.Android
 				UpdateIsSwipeToRefreshEnabled();
 				UpdateFastScrollEnabled();
 				UpdateSelectionMode();
+				UpdateSpinnerColor();
 				UpdateHorizontalScrollBarVisibility();
 				UpdateVerticalScrollBarVisibility();
 			}
@@ -217,6 +218,8 @@ namespace Xamarin.Forms.Platform.Android
 				UpdateFastScrollEnabled();
 			else if (e.PropertyName == ListView.SelectionModeProperty.PropertyName)
 				UpdateSelectionMode();
+			else if (e.PropertyName == ListView.RefreshControlColorProperty.PropertyName)
+				UpdateSpinnerColor();
 			else if (e.PropertyName == ScrollView.HorizontalScrollBarVisibilityProperty.PropertyName)
 				UpdateHorizontalScrollBarVisibility();
 			else if (e.PropertyName == ScrollView.VerticalScrollBarVisibilityProperty.PropertyName)
@@ -419,6 +422,12 @@ namespace Xamarin.Forms.Platform.Android
 			}
 		}
 
+		void UpdateSpinnerColor()
+		{
+			if (_refresh != null)
+				_refresh.SetColorSchemeColors(Element.RefreshControlColor.ToAndroid());
+		}
+
 		void UpdateHorizontalScrollBarVisibility()
 		{
 			if (_defaultHorizontalScrollVisibility == 0)

Xamarin.Forms.Platform.iOS/Renderers/ListViewRenderer.cs

@@ -249,6 +249,7 @@ namespace Xamarin.Forms.Platform.iOS
 				UpdateSeparatorColor();
 				UpdateSeparatorVisibility();
 				UpdateSelectionMode();
+				UpdateSpinnerColor();
 				UpdateVerticalScrollBarVisibility();
 				UpdateHorizontalScrollBarVisibility();
 
@@ -289,6 +290,8 @@ namespace Xamarin.Forms.Platform.iOS
 				UpdatePullToRefreshEnabled();
 			else if (e.PropertyName == Xamarin.Forms.ListView.SelectionModeProperty.PropertyName)
 				UpdateSelectionMode();
+			else if (e.PropertyName == Xamarin.Forms.ListView.RefreshControlColorProperty.PropertyName)
+				UpdateSpinnerColor();
 			else if (e.PropertyName == ScrollView.VerticalScrollBarVisibilityProperty.PropertyName)
 				UpdateVerticalScrollBarVisibility();
 			else if (e.PropertyName == ScrollView.HorizontalScrollBarVisibilityProperty.PropertyName)
@@ -682,6 +685,14 @@ namespace Xamarin.Forms.Platform.iOS
 			}
 		}
 
+		void UpdateSpinnerColor()
+		{
+			var color = Element.RefreshControlColor;
+
+			if (_tableViewController != null)
+				_tableViewController.UpdateRefreshControlColor(color == Color.Default ? null : color.ToUIColor());
+    }
+    
 		void UpdateVerticalScrollBarVisibility()
 		{
 			if (_defaultVerticalScrollVisibility == null)
@@ -1463,6 +1474,12 @@ namespace Xamarin.Forms.Platform.iOS
 			UpdateIsRefreshing(true);
 		}
 
+		public void UpdateRefreshControlColor(UIColor color)
+		{
+			if (RefreshControl != null)
+				RefreshControl.TintColor = color;
+		}
+
 		protected override void Dispose(bool disposing)
 		{
 			if (_disposed)