Introduce a static FontManager that uses a platform implementation under the hood.

src/Avalonia.Visuals/Media/FontFamily.cs

@@ -12,7 +12,7 @@ namespace Avalonia.Media
     {
         static FontFamily()
         {
-            Default = new FontFamily(FontManager.Default.DefaultFontFamilyName);
+            Default = new FontFamily(FontManager.DefaultFontFamilyName);
         }
 
         /// <inheritdoc />
@@ -60,8 +60,11 @@ namespace Avalonia.Media
         /// <summary>
         /// Represents all font families in the system. This can be an expensive call depending on platform implementation.
         /// </summary>
+        /// <remarks>
+        /// Consider using the new <see cref="FontManager"/> instead.
+        /// </remarks>
         public static IEnumerable<FontFamily> SystemFontFamilies =>
-            FontManager.Default.GetInstalledFontFamilyNames().Select(name => new FontFamily(name));
+            FontManager.GetInstalledFontFamilyNames().Select(name => new FontFamily(name));
 
         /// <summary>
         /// Gets the primary family name of the font family.

src/Avalonia.Visuals/Media/FontManager.cs

@@ -1,99 +1,55 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
-using System;
 using System.Collections.Generic;
 using System.Globalization;
 using Avalonia.Platform;
 
 namespace Avalonia.Media
 {
-    public abstract class FontManager : IFontManagerImpl
+    public static class FontManager
     {
-        public static readonly FontManager Default = CreateDefaultFontManger();
+        private static readonly IFontManagerImpl s_platformImpl = GetPlatformImpl();
 
-        /// <inheritdoc cref="IFontManagerImpl"/>
+        /// <inheritdoc cref="IFontManagerImpl.DefaultFontFamilyName"/>
-        public string DefaultFontFamilyName { get; protected set; }
+        public static string DefaultFontFamilyName => s_platformImpl.DefaultFontFamilyName;
 
-        private static FontManager CreateDefaultFontManger()
+        /// <inheritdoc cref="IFontManagerImpl.GetInstalledFontFamilyNames"/>
-        {
+        public static IEnumerable<string> GetInstalledFontFamilyNames(bool checkForUpdates = false) =>
-            var platformImpl = AvaloniaLocator.Current.GetService<IFontManagerImpl>();
+            s_platformImpl.GetInstalledFontFamilyNames(checkForUpdates);
-
-            if(platformImpl == null)
-            {
-                return new EmptyFontManager();
-            }
-
-            return new PlatformFontManger(platformImpl);
-        }
 
-        /// <inheritdoc cref="IFontManagerImpl"/>
+        /// <inheritdoc cref="IFontManagerImpl.GetTypeface"/>
-        public abstract IEnumerable<string> GetInstalledFontFamilyNames(bool checkForUpdates = false);
+        public static Typeface GetTypeface(FontFamily fontFamily, FontWeight fontWeight, FontStyle fontStyle) =>
+            s_platformImpl.GetTypeface(fontFamily, fontWeight, fontStyle);
 
-        /// <inheritdoc cref="IFontManagerImpl"/>
+        /// <inheritdoc cref="IFontManagerImpl.MatchCharacter"/>
-        public abstract IGlyphTypefaceImpl CreateGlyphTypeface(Typeface typeface);
+        public static Typeface MatchCharacter(int codepoint, FontWeight fontWeight = default,
-
-        /// <inheritdoc cref="IFontManagerImpl"/>
-        public abstract Typeface GetTypeface(FontFamily fontFamily, FontWeight fontWeight, FontStyle fontStyle);
-
-        /// <inheritdoc cref="IFontManagerImpl"/>
-        public abstract Typeface MatchCharacter(int codepoint, FontWeight fontWeight = default,
             FontStyle fontStyle = default,
-            FontFamily fontFamily = null, CultureInfo culture = null);
+            FontFamily fontFamily = null, CultureInfo culture = null) =>
+            s_platformImpl.MatchCharacter(codepoint, fontWeight, fontStyle, fontFamily, culture);
 
-        private class PlatformFontManger : FontManager
+        private static IFontManagerImpl GetPlatformImpl()
         {
-            private readonly IFontManagerImpl _platformImpl;
+            var platformImpl = AvaloniaLocator.Current.GetService<IFontManagerImpl>();
-
-            public PlatformFontManger(IFontManagerImpl platformImpl)
-            {
-                _platformImpl = platformImpl;
-
-                DefaultFontFamilyName = _platformImpl.DefaultFontFamilyName;
-            }
-
-            public override IEnumerable<string> GetInstalledFontFamilyNames(bool checkForUpdates = false) =>
-                _platformImpl.GetInstalledFontFamilyNames(checkForUpdates);
-
-            public override IGlyphTypefaceImpl CreateGlyphTypeface(Typeface typeface) => _platformImpl.CreateGlyphTypeface(typeface);
-
-            public override Typeface GetTypeface(FontFamily fontFamily, FontWeight fontWeight, FontStyle fontStyle) =>
-                _platformImpl.GetTypeface(fontFamily, fontWeight, fontStyle);
 
-            public override Typeface MatchCharacter(int codepoint, FontWeight fontWeight = default,
+            return platformImpl ?? new EmptyFontManagerImpl();
-                FontStyle fontStyle = default,
-                FontFamily fontFamily = null, CultureInfo culture = null) =>
-                _platformImpl.MatchCharacter(codepoint, fontWeight, fontStyle, fontFamily, culture);
         }
 
-        private class EmptyFontManager : FontManager
+        private class EmptyFontManagerImpl : IFontManagerImpl
         {
-            private readonly string[] _defaultFontFamilies = { "Arial" };
+            public string DefaultFontFamilyName => "Arial";
-
-            public EmptyFontManager()
-            {
-                DefaultFontFamilyName = "Arial";
-            }
-
-            public override IEnumerable<string> GetInstalledFontFamilyNames(bool checkForUpdates = false)
-            {
-                return _defaultFontFamilies;
-            }
 
-            public override IGlyphTypefaceImpl CreateGlyphTypeface(Typeface typeface)
+            public IEnumerable<string> GetInstalledFontFamilyNames(bool checkForUpdates = false) => new[] { "Arial" };
-            {
-                throw new NotSupportedException();
-            }
 
-            public override Typeface GetTypeface(FontFamily fontFamily, FontWeight fontWeight, FontStyle fontStyle)
+            public Typeface GetTypeface(FontFamily fontFamily, FontWeight fontWeight, FontStyle fontStyle)
             {
-                throw new NotSupportedException();
+                return new Typeface(fontFamily, fontWeight, fontStyle);
             }
 
-            public override Typeface MatchCharacter(int codepoint, FontWeight fontWeight = default, FontStyle fontStyle = default,
+            public Typeface MatchCharacter(int codepoint, FontWeight fontWeight = default, FontStyle fontStyle = default,
                 FontFamily fontFamily = null, CultureInfo culture = null)
             {
-                throw new NotSupportedException();
+                return null;
             }
         }
     }

src/Avalonia.Visuals/Media/GlyphTypeface.cs

@@ -9,7 +9,10 @@ namespace Avalonia.Media
 {
     public class GlyphTypeface : IDisposable
     {
-        public GlyphTypeface(Typeface typeface) : this(FontManager.Default.CreateGlyphTypeface(typeface))
+        private static readonly IPlatformRenderInterface s_platformRenderInterface =
+            AvaloniaLocator.Current.GetService<IPlatformRenderInterface>();
+
+        public GlyphTypeface(Typeface typeface) : this(s_platformRenderInterface.CreateGlyphTypeface(typeface))
         {
         }
 

src/Avalonia.Visuals/Platform/IFontManagerImpl.cs

@@ -20,15 +20,6 @@ namespace Avalonia.Platform
         /// </summary>
         IEnumerable<string> GetInstalledFontFamilyNames(bool checkForUpdates = false);
 
-        /// <summary>
-        ///     Creates a glyph typeface for specified typeface.
-        /// </summary>
-        /// <param name="typeface">The typeface.</param>
-        /// <returns>
-        ///     The glyph typeface implementation.
-        /// </returns>
-        IGlyphTypefaceImpl CreateGlyphTypeface(Typeface typeface);
-
         /// <summary>
         ///     Get a typeface from specified parameters.
         /// </summary>

src/Avalonia.Visuals/Platform/IPlatformRenderInterface.cs

@@ -111,5 +111,14 @@ namespace Avalonia.Platform
         /// <param name="stride">The number of bytes per row.</param>
         /// <returns>An <see cref="IBitmapImpl"/>.</returns>
         IBitmapImpl LoadBitmap(PixelFormat format, IntPtr data, PixelSize size, Vector dpi, int stride);
+
+        /// <summary>
+        ///     Creates a glyph typeface for specified typeface.
+        /// </summary>
+        /// <param name="typeface">The typeface.</param>
+        /// <returns>
+        ///     The glyph typeface implementation.
+        /// </returns>
+        IGlyphTypefaceImpl CreateGlyphTypeface(Typeface typeface);
     }
 }

src/Skia/Avalonia.Skia/FontManagerImpl.cs

@@ -1,7 +1,6 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
-using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Globalization;
 using Avalonia.Media;
@@ -14,9 +13,6 @@ namespace Avalonia.Skia
     {
         private SKFontManager _skFontManager = SKFontManager.Default;
 
-        private readonly ConcurrentDictionary<Typeface, GlyphTypefaceImpl> _glyphTypefaceCache =
-            new ConcurrentDictionary<Typeface, GlyphTypefaceImpl>();
-
         public FontManagerImpl()
         {
             DefaultFontFamilyName = SKTypeface.Default.FamilyName;
@@ -34,11 +30,6 @@ namespace Avalonia.Skia
             return _skFontManager.FontFamilies;
         }
 
-        public IGlyphTypefaceImpl CreateGlyphTypeface(Typeface typeface)
-        {
-            return _glyphTypefaceCache.GetOrAdd(typeface, new GlyphTypefaceImpl(typeface));
-        }
-
         public Typeface GetTypeface(FontFamily fontFamily, FontWeight fontWeight, FontStyle fontStyle)
         {
             return TypefaceCache.Get(fontFamily.Name, fontWeight, fontStyle).Typeface;

src/Skia/Avalonia.Skia/PlatformRenderInterface.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.IO;
 using Avalonia.Controls.Platform.Surfaces;
@@ -17,6 +18,9 @@ namespace Avalonia.Skia
     /// </summary>
     internal class PlatformRenderInterface : IPlatformRenderInterface
     {
+        private readonly ConcurrentDictionary<Typeface, GlyphTypefaceImpl> _glyphTypefaceCache =
+            new ConcurrentDictionary<Typeface, GlyphTypefaceImpl>();
+
         private readonly ICustomSkiaGpu _customSkiaGpu;
 
         private GRContext GrContext { get; }
@@ -150,5 +154,10 @@ namespace Avalonia.Skia
         {
             return new WriteableBitmapImpl(size, dpi, format);
         }
+
+        public IGlyphTypefaceImpl CreateGlyphTypeface(Typeface typeface)
+        {
+            return _glyphTypefaceCache.GetOrAdd(typeface, new GlyphTypefaceImpl(typeface));
+        }
     }
 }

src/Windows/Avalonia.Direct2D1/Direct2D1Platform.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.IO;
 using Avalonia.Controls;
@@ -27,6 +28,8 @@ namespace Avalonia.Direct2D1
 {
     public class Direct2D1Platform : IPlatformRenderInterface
     {
+        private readonly ConcurrentDictionary<Typeface, GlyphTypefaceImpl> _glyphTypefaceCache =
+            new ConcurrentDictionary<Typeface, GlyphTypefaceImpl>();
         private static readonly Direct2D1Platform s_instance = new Direct2D1Platform();
 
         public static SharpDX.Direct3D11.Device Direct3D11Device { get; private set; }
@@ -190,5 +193,10 @@ namespace Avalonia.Direct2D1
         {
             return new WicBitmapImpl(format, data, size, dpi, stride);
         }
+
+        public IGlyphTypefaceImpl CreateGlyphTypeface(Typeface typeface)
+        {
+            return _glyphTypefaceCache.GetOrAdd(typeface, new GlyphTypefaceImpl(typeface));
+        }
     }
 }

src/Windows/Avalonia.Direct2D1/Media/FontManagerImpl.cs

@@ -1,7 +1,6 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
-using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Globalization;
 using Avalonia.Media;
@@ -15,9 +14,6 @@ namespace Avalonia.Direct2D1.Media
 {
     internal class FontManagerImpl : IFontManagerImpl
     {
-        private readonly ConcurrentDictionary<Typeface, GlyphTypefaceImpl> _glyphTypefaceCache =
-            new ConcurrentDictionary<Typeface, GlyphTypefaceImpl>();
-
         public FontManagerImpl()
         {
             //ToDo: Implement a real lookup of the system's default font.
@@ -40,11 +36,6 @@ namespace Avalonia.Direct2D1.Media
             return fontFamilies;
         }
 
-        public IGlyphTypefaceImpl CreateGlyphTypeface(Typeface typeface)
-        {
-            return _glyphTypefaceCache.GetOrAdd(typeface, new GlyphTypefaceImpl(typeface));
-        }
-
         public Typeface GetTypeface(FontFamily fontFamily, FontWeight fontWeight, FontStyle fontStyle)
         {
             //ToDo: Implement caching.