Fix SystemFontCollection nearest match lookup

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

@@ -47,18 +47,23 @@ 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 (!glyphTypefaces.TryAdd(key, glyphTypeface))
-                {
-                    return false;
-                }
+            if(!_fontManager.PlatformImpl.TryCreateGlyphTypeface(familyName, style, weight, stretch, out glyphTypeface) || 
+                !glyphTypeface.FamilyName.Contains(familyName))
+            {
+                //Try to find nearest match first
+                TryGetNearestMatch(glyphTypefaces, key, out glyphTypeface);
             }
 
+            glyphTypefaces.TryAdd(key, glyphTypeface);
+
             return glyphTypeface != null;
         }
 
@@ -101,9 +106,9 @@ 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);
                 }

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.Oblique), out var glyphTypeface));
+
+                    Assert.Equal("Noto Mono", glyphTypeface.FamilyName);
+                }
+            }
+        }
     }
 }