Call GetHicon only once when creation a windows icon

src/Windows/Avalonia.Win32/IconImpl.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Drawing;
-using System.Drawing.Imaging;
 using System.IO;
 using Avalonia.Platform;
 
@@ -8,31 +7,18 @@ namespace Avalonia.Win32
 {
     class IconImpl : IWindowIconImpl
     {
-        private Bitmap bitmap;
-        private Icon icon;
-
-        public IconImpl(Bitmap bitmap)
-        {
-            this.bitmap = bitmap;
-        }
+        private readonly Icon icon;
 
         public IconImpl(Icon icon)
         {
             this.icon = icon;
         }
 
-        public IntPtr HIcon => icon?.Handle ?? bitmap.GetHicon();
+        public IntPtr HIcon => icon.Handle;
 
         public void Save(Stream outputStream)
         {
-            if (icon != null)
-            {
-                icon.Save(outputStream);
-            }
-            else
-            {
-                bitmap.Save(outputStream, ImageFormat.Png);
-            }
+            icon.Save(outputStream);
         }
     }
 }

src/Windows/Avalonia.Win32/TrayIconImpl.cs

@@ -18,6 +18,8 @@ namespace Avalonia.Win32
     [Unstable]
     public class TrayIconImpl : ITrayIconImpl
     {
+        private static readonly IntPtr s_emptyIcon = new System.Drawing.Bitmap(32, 32).GetHicon();
+        
         private readonly int _uniqueId;
         private static int s_nextUniqueId;
         private bool _iconAdded;
@@ -86,7 +88,7 @@ namespace Avalonia.Win32
                 uID = _uniqueId,
                 uFlags = NIF.TIP | NIF.MESSAGE,
                 uCallbackMessage = (int)CustomWindowsMessage.WM_TRAYMOUSE,
-                hIcon = _icon?.HIcon ?? new IconImpl(new System.Drawing.Bitmap(32, 32)).HIcon,
+                hIcon = _icon?.HIcon ?? s_emptyIcon,
                 szTip = _tooltipText ?? ""
             };
 

src/Windows/Avalonia.Win32/Win32Platform.cs

@@ -359,7 +359,7 @@ namespace Avalonia.Win32
             using (var memoryStream = new MemoryStream())
             {
                 bitmap.Save(memoryStream);
-                return new IconImpl(new System.Drawing.Bitmap(memoryStream));
+                return CreateIconImpl(memoryStream);
             }
         }
 
@@ -367,11 +367,15 @@ namespace Avalonia.Win32
         {
             try
             {
+                // new Icon() will work only if stream is an "ico" file.
                 return new IconImpl(new System.Drawing.Icon(stream));
             }
             catch (ArgumentException)
             {
-                return new IconImpl(new System.Drawing.Bitmap(stream));
+                // Fallback to Bitmap creation and converting into a windows icon. 
+                using var icon = new System.Drawing.Bitmap(stream);
+                var hIcon = icon.GetHicon();
+                return new IconImpl(System.Drawing.Icon.FromHandle(hIcon));
             }
         }