Merge pull request #701 from jkoritzinsky/win32-mipmap-icon-support

Use mipmaps for Icons when icon is an .ico file.

src/Windows/Avalonia.Win32/IconImpl.cs

@@ -1,6 +1,7 @@
 using Avalonia.Platform;
 using System;
 using System.Collections.Generic;
+using System.Drawing;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
@@ -9,11 +10,19 @@ namespace Avalonia.Win32
 {
     class IconImpl : IWindowIconImpl
     {
-        public IconImpl(System.Drawing.Bitmap iconBitmap)
+        private Bitmap bitmap;
+        private Icon icon;
+
+        public IconImpl(Bitmap bitmap)
+        {
+            this.bitmap = bitmap;
+        }
+
+        public IconImpl(Icon icon)
         {
-            IconBitmap = iconBitmap;
+            this.icon = icon;
         }
 
-        public System.Drawing.Bitmap IconBitmap { get; }
+        public IntPtr HIcon => icon?.Handle ?? bitmap.GetHicon();
     }
 }

src/Windows/Avalonia.Win32/Win32Platform.cs

@@ -189,14 +189,15 @@ namespace Avalonia.Win32
 
         public IWindowIconImpl LoadIcon(string fileName)
         {
-            var icon = new System.Drawing.Bitmap(fileName);
-            return new IconImpl(icon);
+            using (var stream = File.OpenRead(fileName))
+            {
+                return CreateImpl(stream); 
+            }
         }
 
         public IWindowIconImpl LoadIcon(Stream stream)
         {
-            var icon = new System.Drawing.Bitmap(stream);
-            return new IconImpl(icon);
+            return CreateImpl(stream);
         }
 
         public IWindowIconImpl LoadIcon(IBitmapImpl bitmap)
@@ -207,5 +208,17 @@ namespace Avalonia.Win32
                 return new IconImpl(new System.Drawing.Bitmap(memoryStream));
             }
         }
+
+        private static IconImpl CreateImpl(Stream stream)
+        {
+            try
+            {
+                return new IconImpl(new System.Drawing.Icon(stream));
+            }
+            catch (ArgumentException)
+            {
+                return new IconImpl(new System.Drawing.Bitmap(stream));
+            }
+        }
     }
 }

src/Windows/Avalonia.Win32/WindowImpl.cs

@@ -684,9 +684,9 @@ namespace Avalonia.Win32
         public void SetIcon(IWindowIconImpl icon)
         {
             var impl = (IconImpl)icon;
-            var nativeIcon = impl.IconBitmap;
+            var hIcon = impl.HIcon;
             UnmanagedMethods.PostMessage(_hwnd, (int)UnmanagedMethods.WindowsMessage.WM_SETICON,
-                new IntPtr((int)UnmanagedMethods.Icons.ICON_BIG), nativeIcon.GetHicon());
+                new IntPtr((int)UnmanagedMethods.Icons.ICON_BIG), hIcon);
         }
 
         private static int ToInt32(IntPtr ptr)