1 files changed, 78 insertions, 0 deletions
diff --git a/Xamarin.Forms.Platform.MacOS/CADisplayLinkTicker.cs b/Xamarin.Forms.Platform.MacOS/CADisplayLinkTicker.cs
new file mode 100644
index 00000000..1e965ff5
--- /dev/null
+++ b/Xamarin.Forms.Platform.MacOS/CADisplayLinkTicker.cs
@@ -0,0 +1,78 @@
+using System;
+using System.Collections.Concurrent;
+using System.Threading;
+using Foundation;
+using Xamarin.Forms.Internals;
+using CoreVideo;
+using AppKit;
+using CoreAnimation;
+
+namespace Xamarin.Forms.Platform.MacOS
+{
+	// ReSharper disable once InconsistentNaming
+	internal class CADisplayLinkTicker : Ticker
+	{
+		readonly BlockingCollection<Action> _queue = new BlockingCollection<Action>();
+		CVDisplayLink _link;
+
+		public CADisplayLinkTicker()
+		{
+			var thread = new Thread(StartThread);
+			thread.Start();
+		}
+
+		internal new static CADisplayLinkTicker Default => Ticker.Default as CADisplayLinkTicker;
+
+		public void Invoke(Action action)
+		{
+			_queue.Add(action);
+		}
+
+		protected override void DisableTimer()
+		{
+			_link?.Stop();
+			_link?.Dispose();
+			_link = null;
+		}
+
+		protected override void EnableTimer()
+		{
+			_link = new CVDisplayLink();
+			_link.SetOutputCallback(DisplayLinkOutputCallback);
+			_link.Start();
+		}
+
+		public CVReturn DisplayLinkOutputCallback(CVDisplayLink displayLink, ref CVTimeStamp inNow,
+			ref CVTimeStamp inOutputTime, CVOptionFlags flagsIn, ref CVOptionFlags flagsOut)
+		{
+			// There is no autorelease pool when this method is called because it will be called from a background thread
+			// It's important to create one or you will leak objects
+			// ReSharper disable once UnusedVariable
+			using (var pool = new NSAutoreleasePool())
+			{
+				Device.BeginInvokeOnMainThread(() => SendSignals());
+			}
+			return CVReturn.Success;
+		}
+
+		void StartThread()
+		{
+			while (true)
+			{
+				Action action = _queue.Take();
+				bool previous = NSApplication.CheckForIllegalCrossThreadCalls;
+				NSApplication.CheckForIllegalCrossThreadCalls = false;
+
+				CATransaction.Begin();
+				action.Invoke();
+
+				while (_queue.TryTake(out action))
+					action.Invoke();
+				CATransaction.Commit();
+
+				NSApplication.CheckForIllegalCrossThreadCalls = previous;
+			}
+			// ReSharper disable once FunctionNeverReturns
+		}
+	}
+}
+\ No newline at end of file