From 48e3ac56fc75ad45fa0b97285617ae9fb027d9b5 Mon Sep 17 00:00:00 2001
From: Rupert Benbrook <rupert@altitudeangel.com>
Date: Thu, 9 Nov 2023 13:10:11 +0000
Subject: [PATCH] Fixing a performance problem in message display

---
 .../ControlOverlayMessageDisplay.cs           | 13 ++++--
 .../AltitudeAngelWings/ObservableProperty.cs  |  4 +-
 .../Service/Messaging/IMessagesService.cs     |  1 -
 .../Service/Messaging/MessagesService.cs      | 41 +++++++------------
 4 files changed, 27 insertions(+), 32 deletions(-)

diff --git a/ExtLibs/AltitudeAngelWings.Plugin/ControlOverlayMessageDisplay.cs b/ExtLibs/AltitudeAngelWings.Plugin/ControlOverlayMessageDisplay.cs
index 55b323bc7c..aceeb70ab7 100644
--- a/ExtLibs/AltitudeAngelWings.Plugin/ControlOverlayMessageDisplay.cs
+++ b/ExtLibs/AltitudeAngelWings.Plugin/ControlOverlayMessageDisplay.cs
@@ -56,15 +56,22 @@ public void RemoveMessage(Message message)
                 if (!_parent.Visible) return;
                 _parent.SuspendLayout();
                 var labels = GetMessageLabels();
+                var removed = false;
                 foreach (var label in labels)
                 {
                     if (label.Tag != message) continue;
                     _parent.Controls.Remove(label);
                     labels.Remove(label);
                     label.Dispose();
+                    removed = true;
                     break;
                 }
-                LayoutLabels(labels);
+
+                if (removed)
+                {
+                    LayoutLabels(labels);
+                }
+
                 _parent.ResumeLayout();
             });
         }
@@ -110,7 +117,7 @@ private static Color GetColorForMessage(Message message)
             }
         }
 
-        private void LayoutLabels(ICollection<Label> labels)
+        private void LayoutLabels(IEnumerable<Label> labels)
         {
             var totalHeight = 0;
             foreach (var label in labels)
@@ -122,4 +129,4 @@ private void LayoutLabels(ICollection<Label> labels)
 
         private IList<Label> GetMessageLabels() => _parent.Controls.OfType<Label>().Where(l => l.Tag is Message).ToList();
     }
-}
\ No newline at end of file
+}
diff --git a/ExtLibs/AltitudeAngelWings/ObservableProperty.cs b/ExtLibs/AltitudeAngelWings/ObservableProperty.cs
index 47fec7425e..0969970697 100644
--- a/ExtLibs/AltitudeAngelWings/ObservableProperty.cs
+++ b/ExtLibs/AltitudeAngelWings/ObservableProperty.cs
@@ -7,7 +7,7 @@ namespace AltitudeAngelWings
 {
     public class ObservableProperty<T> : INotifyPropertyChanged, IObservable<T>, IDisposable
     {
-        private readonly ISubject<T> _subject;
+        private readonly ReplaySubject<T> _subject;
         private T _value;
 
         public ObservableProperty()
@@ -68,7 +68,7 @@ protected virtual void Dispose(bool disposing)
         {
             if (disposing)
             {
-                ((IDisposable)_subject)?.Dispose();
+                _subject?.Dispose();
             }
         }
 
diff --git a/ExtLibs/AltitudeAngelWings/Service/Messaging/IMessagesService.cs b/ExtLibs/AltitudeAngelWings/Service/Messaging/IMessagesService.cs
index d4631abd60..e4631da543 100644
--- a/ExtLibs/AltitudeAngelWings/Service/Messaging/IMessagesService.cs
+++ b/ExtLibs/AltitudeAngelWings/Service/Messaging/IMessagesService.cs
@@ -5,7 +5,6 @@ namespace AltitudeAngelWings.Service.Messaging
 {
     public interface IMessagesService
     {
-        ObservableProperty<Message> Messages { get; }
         Task AddMessageAsync(Message message);
     }
 }
diff --git a/ExtLibs/AltitudeAngelWings/Service/Messaging/MessagesService.cs b/ExtLibs/AltitudeAngelWings/Service/Messaging/MessagesService.cs
index 52b1298721..ec73d5627f 100644
--- a/ExtLibs/AltitudeAngelWings/Service/Messaging/MessagesService.cs
+++ b/ExtLibs/AltitudeAngelWings/Service/Messaging/MessagesService.cs
@@ -1,43 +1,32 @@
 using System;
-using System.Reactive.Disposables;
-using System.Reactive.Linq;
 using System.Threading.Tasks;
 using AltitudeAngelWings.Model;
 
 namespace AltitudeAngelWings.Service.Messaging
 {
-    public class MessagesService : IMessagesService, IDisposable
+    public class MessagesService : IMessagesService
     {
-        private readonly CompositeDisposable _disposer = new CompositeDisposable();
+        private readonly IMessageDisplay _messageDisplay;
 
         public MessagesService(IMessageDisplay messageDisplay)
         {
-            Messages = new ObservableProperty<Message>(0);
-            _disposer.Add(Messages);
-            _disposer.Add(Messages
-                .Do(messageDisplay.AddMessage)
-                .SelectMany(m => Observable.Interval(TimeSpan.FromMilliseconds(100))
-                    .SkipWhile(i => !m.HasExpired())
-                    .Select(i => m))
-                .Subscribe(messageDisplay.RemoveMessage));
+            _messageDisplay = messageDisplay;
         }
 
-        public ObservableProperty<Message> Messages { get; }
-
-        public Task AddMessageAsync(Message message) => Task.Factory.StartNew(() => Messages.Value = message);
-
-        public void Dispose()
-        {
-            Dispose(true);
-            GC.SuppressFinalize(this);
-        }
-
-        protected virtual void Dispose(bool disposing)
+        public Task AddMessageAsync(Message message) => Task.Factory.StartNew(async () =>
         {
-            if (disposing)
+            try
             {
-                _disposer?.Dispose();
+                _messageDisplay.AddMessage(message);
+                do
+                {
+                    await Task.Delay(TimeSpan.FromMilliseconds(200)).ConfigureAwait(false);
+                } while (!message.HasExpired());
             }
-        }
+            finally
+            {
+                _messageDisplay.RemoveMessage(message);
+            }
+        });
     }
 }