[MacOS] Context actions (#727)

* [MacOS] Add ContextActions

* [MacOS] Implement ContextActions

Xamarin.Forms.Platform.MacOS/Cells/CellNSView.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Linq;
 using System.ComponentModel;
 using AppKit;
 using CoreGraphics;
@@ -11,6 +12,7 @@ namespace Xamarin.Forms.Platform.MacOS
 		static readonly CGColor s_defaultHeaderViewsBackground = NSColor.LightGray.CGColor;
 		Cell _cell;
 		readonly NSTableViewCellStyle _style;
+		NSView _contexActionsTrackingView;
 
 		public Action<object, PropertyChangedEventArgs> PropertyChanged;
 
@@ -29,7 +31,7 @@ namespace Xamarin.Forms.Platform.MacOS
 
 		public NSView AccessoryView { get; private set; }
 
-		public Element Element => Cell;
+		public virtual Element Element => Cell;
 
 		public Cell Cell
 		{
@@ -92,14 +94,26 @@ namespace Xamarin.Forms.Platform.MacOS
 			nfloat labelHeights = availableHeight;
 			nfloat labelWidth = availableWidth - imageWidth - accessoryViewWidth;
 
+			if (DetailTextLabel != null)
+			{
+
 				if (!string.IsNullOrEmpty(DetailTextLabel?.StringValue))
 				{
 					labelHeights = availableHeight / 2;
 					DetailTextLabel.CenterTextVertically(new CGRect(imageWidth + padding, 0, labelWidth, labelHeights));
 				}
+			}
 
-			TextLabel.CenterTextVertically(new CGRect(imageWidth + padding, availableHeight - labelHeights, labelWidth,
+			TextLabel?.CenterTextVertically(new CGRect(imageWidth + padding, availableHeight - labelHeights, labelWidth,
 				labelHeights));
+
+			var topNSView = Subviews.LastOrDefault();
+			if (_contexActionsTrackingView != topNSView)
+			{
+				_contexActionsTrackingView.RemoveFromSuperview();
+				_contexActionsTrackingView.Frame = Frame;
+				AddSubview(_contexActionsTrackingView, NSWindowOrderingMode.Above, Subviews.LastOrDefault());
+			}
 			base.Layout();
 		}
 
@@ -129,7 +143,8 @@ namespace Xamarin.Forms.Platform.MacOS
 		void CreateUI()
 		{
 			var style = _style;
-
+			if (style != NSTableViewCellStyle.Empty)
+			{
 				AddSubview(TextLabel = new NSTextField
 				{
 					Bordered = false,
@@ -163,5 +178,51 @@ namespace Xamarin.Forms.Platform.MacOS
 					AddSubview(AccessoryView = accessoryView);
 				}
 			}
+			AddSubview(_contexActionsTrackingView = new TrackingClickNSView());
+		}
+	}
+
+	class TrackingClickNSView : NSView
+	{
+		public override void RightMouseDown(NSEvent theEvent)
+		{
+			HandleContextActions(theEvent);
+
+			base.RightMouseDown(theEvent);
+		}
+
+		void HandleContextActions(NSEvent theEvent)
+		{
+			var contextActionCell = (Superview as INativeElementView).Element as Cell;
+			var contextActionsCount = contextActionCell.ContextActions.Count;
+			if (contextActionsCount > 0)
+			{
+				NSMenu menu = new NSMenu();
+				for (int i = 0; i < contextActionsCount; i++)
+				{
+					var contextAction = contextActionCell.ContextActions[i];
+					var nsMenuItem = GetNSMenuItem(i, contextAction);
+					menu.AddItem(nsMenuItem);
+				}
+
+				NSMenu.PopUpContextMenu(menu, theEvent, this);
+			}
+		}
+
+		static NSMenuItem GetNSMenuItem(int i, MenuItem contextAction)
+		{
+			var menuItem = new NSMenuItem(contextAction.Text ?? "");
+			menuItem.Tag = i;
+			menuItem.Enabled = contextAction.IsEnabled;
+			if (menuItem.Enabled)
+				menuItem.Activated += (sender, e) =>
+				{
+					((IMenuItemController)contextAction).Activate();
+				};
+			if (!string.IsNullOrEmpty(contextAction.Icon))
+				menuItem.Image = new NSImage(contextAction.Icon);
+
+			return menuItem;
+		}
 	}
 }

Xamarin.Forms.Platform.MacOS/Cells/NSTableViewCellStyle.cs

@@ -7,6 +7,7 @@
 		Value2,
 		Subtitle,
 		Image,
-		ImageSubtitle
+		ImageSubtitle,
+		Empty
 	}
 }

Xamarin.Forms.Platform.MacOS/Cells/ViewCellNSView.cs

@@ -4,13 +4,18 @@ using RectangleF = CoreGraphics.CGRect;
 
 namespace Xamarin.Forms.Platform.MacOS
 {
-	public class ViewCellNSView : NSView, INativeElementView
+	internal class ViewCellNSView : CellNSView
 	{
+		public ViewCellNSView() : base(NSTableViewCellStyle.Empty)
+		{
+
+		}
+
 		WeakReference<IVisualElementRenderer> _rendererRef;
 
 		ViewCell _viewCell;
 
-		public Element Element => ViewCell;
+		public override Element Element => ViewCell;
 
 		public ViewCell ViewCell
 		{

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

@@ -20,7 +20,7 @@ namespace Xamarin.Forms.Platform.MacOS
 
 		ITemplatedItemsView<Cell> TemplatedItemsView => Element;
 
-		public const int DefaultRowHeight = 16;
+		public const int DefaultRowHeight = 44;
 
 		public NSTableView NativeTableView => _table;