Fix SystemFontCollection nearest match lookup

src/Avalonia.Base/Media/Fonts/EmbeddedFontCollection.cs

@@ -16,6 +16,8 @@ public class EmbeddedFontCollection : FontCollectionBase
 
         private readonly Uri _source;
 
+        private IFontManagerImpl? _fontManager;
+
         public EmbeddedFontCollection(Uri key, Uri source)
         {
             _key = key;
@@ -31,6 +33,8 @@ public EmbeddedFontCollection(Uri key, Uri source)
 
         public override void Initialize(IFontManagerImpl fontManager)
         {
+            _fontManager = fontManager;
+
             var assetLoader = AvaloniaLocator.Current.GetRequiredService<IAssetLoader>();
 
             var fontAssets = FontFamilyLoader.LoadFontAssets(_source);
@@ -39,7 +43,7 @@ public override void Initialize(IFontManagerImpl fontManager)
             {
                 var stream = assetLoader.Open(fontAsset);
 
-                if (fontManager.TryCreateGlyphTypeface(stream, out var glyphTypeface))
+                if (fontManager.TryCreateGlyphTypeface(stream, FontSimulations.None, out var glyphTypeface))
                 {
                     if (!_glyphTypefaceCache.TryGetValue(glyphTypeface.FamilyName, out var glyphTypefaces))
                     {
@@ -69,8 +73,42 @@ public override bool TryGetGlyphTypeface(string familyName, FontStyle style, Fon
 
             if (_glyphTypefaceCache.TryGetValue(familyName, out var glyphTypefaces))
             {
+                if (glyphTypefaces.TryGetValue(key, out glyphTypeface) && glyphTypeface != null)
+                {
+                    return true;
+                }
+
                 if (TryGetNearestMatch(glyphTypefaces, key, out glyphTypeface))
                 {
+                    if (glyphTypeface is IGlyphTypeface2 glyphTypeface2)
+                    {
+                        var fontSimulations = FontSimulations.None;
+
+                        if (style != FontStyle.Normal && glyphTypeface2.Style != style)
+                        {
+                            fontSimulations |= FontSimulations.Oblique;
+                        }
+
+                        if ((int)weight >= 600 && glyphTypeface2.Weight != weight)
+                        {
+                            fontSimulations |= FontSimulations.Bold;
+                        }
+
+                        if (fontSimulations != FontSimulations.None && glyphTypeface2.TryGetStream(out var stream))
+                        {
+                            using (stream)
+                            {
+                                if(_fontManager is not null && _fontManager.TryCreateGlyphTypeface(stream, fontSimulations, out glyphTypeface) && 
+                                    glyphTypefaces.TryAdd(key, glyphTypeface))
+                                {
+                                    return true;
+                                }
+
+                                return false;
+                            }
+                        }
+                    }
+
                     return true;
                 }
             }

src/Avalonia.Base/Media/Fonts/SystemFontCollection.cs

@@ -47,18 +47,46 @@ public override bool TryGetGlyphTypeface(string familyName, FontStyle style, Fon
 
             var key = new FontCollectionKey(style, weight, stretch);
 
-            var glyphTypefaces = _glyphTypefaceCache.GetOrAdd(familyName, (key) => new ConcurrentDictionary<FontCollectionKey, IGlyphTypeface?>());
+            var glyphTypefaces = _glyphTypefaceCache.GetOrAdd(familyName,
+                (_) => new ConcurrentDictionary<FontCollectionKey, IGlyphTypeface?>());
 
-            if (!glyphTypefaces.TryGetValue(key, out glyphTypeface))
+            if (glyphTypefaces.TryGetValue(key, out glyphTypeface))
             {
-                _fontManager.PlatformImpl.TryCreateGlyphTypeface(familyName, style, weight, stretch, out glyphTypeface);
+                return glyphTypeface != null;
+            }
+
+            if(!_fontManager.PlatformImpl.TryCreateGlyphTypeface(familyName, style, weight, stretch, out glyphTypeface) || 
+                !glyphTypeface.FamilyName.Contains(familyName))
+            {
+                //Try to find nearest match if possible
+                TryGetNearestMatch(glyphTypefaces, key, out glyphTypeface);
+            }
 
-                if (!glyphTypefaces.TryAdd(key, glyphTypeface))
+            if(glyphTypeface is IGlyphTypeface2 glyphTypeface2)
+            {
+                var fontSimulations = FontSimulations.None;
+
+                if(style != FontStyle.Normal && glyphTypeface2.Style != style)
                 {
-                    return false;
+                    fontSimulations |= FontSimulations.Oblique;
+                }
+
+                if((int)weight >= 600 && glyphTypeface2.Weight != weight)
+                {
+                    fontSimulations |= FontSimulations.Bold;
+                }
+
+                if(fontSimulations != FontSimulations.None && glyphTypeface2.TryGetStream(out var stream))
+                {
+                    using (stream)
+                    {
+                        _fontManager.PlatformImpl.TryCreateGlyphTypeface(stream, fontSimulations, out glyphTypeface);
+                    }
                 }
             }
 
+            glyphTypefaces.TryAdd(key, glyphTypeface);
+
             return glyphTypeface != null;
         }
 
@@ -87,7 +115,7 @@ private void LoadGlyphTypefaces(IFontManagerImpl fontManager, Uri source)
             {
                 var stream = assetLoader.Open(fontAsset);
 
-                if (fontManager.TryCreateGlyphTypeface(stream, out var glyphTypeface))
+                if (fontManager.TryCreateGlyphTypeface(stream, FontSimulations.None, out var glyphTypeface))
                 {
                     if (!_glyphTypefaceCache.TryGetValue(glyphTypeface.FamilyName, out var glyphTypefaces))
                     {
@@ -101,9 +129,9 @@ private void LoadGlyphTypefaces(IFontManagerImpl fontManager, Uri source)
                     }
 
                     var key = new FontCollectionKey(
-                           glyphTypeface.Style,
-                           glyphTypeface.Weight,
-                           glyphTypeface.Stretch);
+                        glyphTypeface.Style,
+                        glyphTypeface.Weight,
+                        glyphTypeface.Stretch);
 
                     glyphTypefaces.TryAdd(key, glyphTypeface);
                 }

src/Avalonia.Base/Platform/IFontManagerImpl.cs

@@ -53,10 +53,11 @@ bool TryCreateGlyphTypeface(string familyName, FontStyle style, FontWeight weigh
         ///     Tries to create a glyph typeface from specified stream.
         /// </summary>
         /// <param name="stream">A stream that holds the font's data.</param>
+        /// <param name="fontSimulations">Specifies algorithmic style simulations.</param>
         /// <param name="glyphTypeface">The created glyphTypeface</param>
         /// <returns>
         ///     <c>True</c>, if the <see cref="IFontManagerImpl"/> could create the glyph typeface, <c>False</c> otherwise.
         /// </returns>
-        bool TryCreateGlyphTypeface(Stream stream, [NotNullWhen(returnValue: true)] out IGlyphTypeface? glyphTypeface);
+        bool TryCreateGlyphTypeface(Stream stream, FontSimulations fontSimulations, [NotNullWhen(returnValue: true)] out IGlyphTypeface? glyphTypeface);
     }
 }

src/Headless/Avalonia.Headless/HeadlessPlatformStubs.cs

@@ -242,10 +242,12 @@ public virtual bool TryCreateGlyphTypeface(string familyName, FontStyle style, F
             return true;
         }
 
-        public virtual bool TryCreateGlyphTypeface(Stream stream, out IGlyphTypeface glyphTypeface)
+        public virtual bool TryCreateGlyphTypeface(Stream stream, FontSimulations fontSimulations, out IGlyphTypeface glyphTypeface)
         {
             glyphTypeface = new HeadlessGlyphTypefaceImpl();
 
+            TryCreateGlyphTypefaceCount++;
+
             return true;
         }
     }
@@ -301,7 +303,7 @@ public virtual bool TryCreateGlyphTypeface(string familyName, FontStyle style, F
             return true;
         }
 
-        public virtual bool TryCreateGlyphTypeface(Stream stream, out IGlyphTypeface glyphTypeface)
+        public virtual bool TryCreateGlyphTypeface(Stream stream, FontSimulations fontSimulations, out IGlyphTypeface glyphTypeface)
         {
             glyphTypeface = new HeadlessGlyphTypefaceImpl();
 

src/Skia/Avalonia.Skia/FontManagerImpl.cs

@@ -105,13 +105,13 @@ public bool TryCreateGlyphTypeface(string familyName, FontStyle style, FontWeigh
             return true;
         }
 
-        public bool TryCreateGlyphTypeface(Stream stream, [NotNullWhen(true)] out IGlyphTypeface? glyphTypeface)
+        public bool TryCreateGlyphTypeface(Stream stream, FontSimulations fontSimulations, [NotNullWhen(true)] out IGlyphTypeface? glyphTypeface)
         {
             var skTypeface = SKTypeface.FromStream(stream);
 
             if (skTypeface != null)
             {
-                glyphTypeface = new GlyphTypefaceImpl(skTypeface, FontSimulations.None);
+                glyphTypeface = new GlyphTypefaceImpl(skTypeface, fontSimulations);
 
                 return true;
             }

src/Skia/Avalonia.Skia/GlyphTypefaceImpl.cs

@@ -164,7 +164,7 @@ public int[] GetGlyphAdvances(ReadOnlySpan<ushort> glyphs)
         }
 
         public SKFont CreateSKFont(float size)
-            => new(_typeface, size, skewX: (FontSimulations & FontSimulations.Oblique) != 0 ? -0.2f : 0.0f)
+            => new(_typeface, size, skewX: (FontSimulations & FontSimulations.Oblique) != 0 ? -0.3f : 0.0f)
             {
                 LinearMetrics = true,
                 Embolden = (FontSimulations & FontSimulations.Bold) != 0

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

@@ -88,7 +88,7 @@ public bool TryCreateGlyphTypeface(string familyName, FontStyle style, FontWeigh
             return false;
         }
 
-        public bool TryCreateGlyphTypeface(Stream stream, out IGlyphTypeface glyphTypeface)
+        public bool TryCreateGlyphTypeface(Stream stream, FontSimulations fontSimulations, out IGlyphTypeface glyphTypeface)
         {
             var fontLoader = new DWriteResourceFontLoader(Direct2D1Platform.DirectWriteFactory, new[] { stream });
 

tests/Avalonia.Skia.UnitTests/Media/CustomFontManagerImpl.cs

@@ -86,11 +86,11 @@ public bool TryCreateGlyphTypeface(string familyName, FontStyle style, FontWeigh
             return true;
         }
 
-        public bool TryCreateGlyphTypeface(Stream stream, [NotNullWhen(true)] out IGlyphTypeface glyphTypeface)
+        public bool TryCreateGlyphTypeface(Stream stream, FontSimulations fontSimulations, [NotNullWhen(true)] out IGlyphTypeface glyphTypeface)
         {
             var skTypeface = SKTypeface.FromStream(stream);
 
-            glyphTypeface = new GlyphTypefaceImpl(skTypeface, FontSimulations.None);
+            glyphTypeface = new GlyphTypefaceImpl(skTypeface, fontSimulations);
 
             return true;
         }

tests/Avalonia.Skia.UnitTests/Media/FontManagerTests.cs

@@ -239,5 +239,26 @@ public void Should_Use_Custom_SystemFont()
                 }
             }
         }
+
+
+        [Fact]
+        public void Should_Get_Nearest_Match_For_Custom_SystemFont()
+        {
+            using (UnitTestApplication.Start(TestServices.MockPlatformRenderInterface.With(fontManagerImpl: new FontManagerImpl())))
+            {
+                using (AvaloniaLocator.EnterScope())
+                {
+                    var systemFontCollection = FontManager.Current.SystemFonts as SystemFontCollection;
+
+                    Assert.NotNull(systemFontCollection);
+
+                    systemFontCollection.AddCustomFontSource(new Uri(s_fontUri, UriKind.Absolute));
+
+                    Assert.True(FontManager.Current.TryGetGlyphTypeface(new Typeface("Noto Mono", FontStyle.Italic), out var glyphTypeface));
+
+                    Assert.Equal("Noto Mono", glyphTypeface.FamilyName);
+                }
+            }
+        }
     }
 }

tests/Avalonia.UnitTests/HarfBuzzFontManagerImpl.cs

@@ -57,7 +57,7 @@ public bool TryMatchCharacter(int codepoint, FontStyle fontStyle, FontWeight fon
             return false;
         }
 
-        public bool TryCreateGlyphTypeface(Stream stream, out IGlyphTypeface glyphTypeface)
+        public bool TryCreateGlyphTypeface(Stream stream, FontSimulations fontSimulations, out IGlyphTypeface glyphTypeface)
         {
             glyphTypeface = new HarfBuzzGlyphTypefaceImpl(stream);