Deal with non standard oblique typefaces on Windows (#19876)

src/Skia/Avalonia.Skia/FontManagerImpl.cs

@@ -50,7 +50,7 @@ namespace Avalonia.Skia
                     skFontStyle = SKFontStyle.BoldItalic;
                     break;
                 default:
-                    skFontStyle = new SKFontStyle((SKFontStyleWeight)fontWeight, (SKFontStyleWidth)fontStretch, (SKFontStyleSlant)fontStyle);
+                    skFontStyle = new SKFontStyle((SKFontStyleWeight)fontWeight, (SKFontStyleWidth)fontStretch, fontStyle.ToSkia());
                     break;
             }
 
@@ -63,7 +63,12 @@ namespace Avalonia.Skia
 
             if (skTypeface != null)
             {
-                fontKey = new Typeface(skTypeface.FamilyName, (FontStyle)skTypeface.FontStyle.Slant, (FontWeight)skTypeface.FontStyle.Weight, (FontStretch)skTypeface.FontStyle.Width);
+                // ToDo: create glyph typeface here to get the correct style/weight/stretch
+                fontKey = new Typeface(
+                    skTypeface.FamilyName,
+                    skTypeface.FontStyle.Slant.ToAvalonia(),
+                    (FontWeight)skTypeface.FontStyle.Weight,
+                    (FontStretch)skTypeface.FontStyle.Width);
 
                 return true;
             }
@@ -78,8 +83,7 @@ namespace Avalonia.Skia
         {
             glyphTypeface = null;
 
-            var fontStyle = new SKFontStyle((SKFontStyleWeight)weight, (SKFontStyleWidth)stretch,
+            var fontStyle = new SKFontStyle((SKFontStyleWeight)weight, (SKFontStyleWidth)stretch, style.ToSkia());
-                (SKFontStyleSlant)style);
 
             var skTypeface = _skFontManager.MatchFamily(familyName, fontStyle);
 
@@ -127,7 +131,7 @@ namespace Avalonia.Skia
 
             var set = _skFontManager.GetFontStyles(familyName);
 
-            if(set.Count == 0)
+            if (set.Count == 0)
             {
                 return false;
             }

src/Skia/Avalonia.Skia/GlyphTypefaceImpl.cs

@@ -16,7 +16,6 @@ namespace Avalonia.Skia
     internal class GlyphTypefaceImpl : IGlyphTypeface2
     {
         private bool _isDisposed;
-        private readonly SKTypeface _typeface;
         private readonly NameTable? _nameTable;
         private readonly OS2Table? _os2Table;
         private readonly HorizontalHeadTable? _hhTable;
@@ -24,7 +23,7 @@ namespace Avalonia.Skia
 
         public GlyphTypefaceImpl(SKTypeface typeface, FontSimulations fontSimulations)
         {
-            _typeface = typeface ?? throw new ArgumentNullException(nameof(typeface));
+            SKTypeface = typeface ?? throw new ArgumentNullException(nameof(typeface));
 
             Face = new Face(GetTable) { UnitsPerEm = typeface.UnitsPerEm };
 
@@ -96,6 +95,11 @@ namespace Avalonia.Skia
 
             var style = _os2Table != null ? GetFontStyle(_os2Table.FontStyle) : FontStyle.Normal;
 
+            if (typeface.FontStyle.Slant == SKFontStyleSlant.Oblique)
+            {
+                style = FontStyle.Oblique;
+            }
+
             Style = (fontSimulations & FontSimulations.Oblique) != 0 ? FontStyle.Italic : style;
 
             var stretch = _os2Table != null ? (FontStretch)_os2Table.WidthClass : FontStretch.Normal;
@@ -205,6 +209,8 @@ namespace Avalonia.Skia
             }
         }
 
+        public SKTypeface SKTypeface { get; }
+
         public Face Face { get; }
 
         public Font Font { get; }
@@ -300,12 +306,12 @@ namespace Avalonia.Skia
 
         private static FontStyle GetFontStyle(OS2Table.FontStyleSelection styleSelection)
         {
-            if((styleSelection & OS2Table.FontStyleSelection.ITALIC) != 0)
+            if ((styleSelection & OS2Table.FontStyleSelection.ITALIC) != 0)
             {
                 return FontStyle.Italic;
             }
 
-            if((styleSelection & OS2Table.FontStyleSelection.OBLIQUE) != 0)
+            if ((styleSelection & OS2Table.FontStyleSelection.OBLIQUE) != 0)
             {
                 return FontStyle.Oblique;
             }
@@ -315,18 +321,18 @@ namespace Avalonia.Skia
 
         private Blob? GetTable(Face face, Tag tag)
         {
-            var size = _typeface.GetTableSize(tag);
+            var size = SKTypeface.GetTableSize(tag);
 
             var data = Marshal.AllocCoTaskMem(size);
 
             var releaseDelegate = new ReleaseDelegate(() => Marshal.FreeCoTaskMem(data));
 
-            return _typeface.TryGetTableData(tag, 0, size, data) ?
+            return SKTypeface.TryGetTableData(tag, 0, size, data) ?
                 new Blob(data, size, MemoryMode.ReadOnly, releaseDelegate) : null;
         }
 
         public SKFont CreateSKFont(float size)
-            => new(_typeface, size, skewX: (FontSimulations & FontSimulations.Oblique) != 0 ? -0.3f : 0.0f)
+            => new(SKTypeface, size, skewX: (FontSimulations & FontSimulations.Oblique) != 0 ? -0.3f : 0.0f)
             {
                 LinearMetrics = true,
                 Embolden = (FontSimulations & FontSimulations.Bold) != 0
@@ -348,7 +354,7 @@ namespace Avalonia.Skia
 
             Font.Dispose();
             Face.Dispose();
-            _typeface.Dispose();
+            SKTypeface.Dispose();
         }
 
         public void Dispose()
@@ -359,14 +365,14 @@ namespace Avalonia.Skia
 
         public bool TryGetTable(uint tag, out byte[] table)
         {
-            return _typeface.TryGetTableData(tag, out table);
+            return SKTypeface.TryGetTableData(tag, out table);
         }
 
         public bool TryGetStream([NotNullWhen(true)] out Stream? stream)
         {
             try
             {
-                var asset = _typeface.OpenStream();
+                var asset = SKTypeface.OpenStream();
                 var size = asset.Length;
                 var buffer = new byte[size];
 

src/Skia/Avalonia.Skia/SkiaSharpExtensions.cs

@@ -1,8 +1,8 @@
 using System;
 using System.Diagnostics.CodeAnalysis;
 using Avalonia.Media;
-using Avalonia.Platform;
 using Avalonia.Media.Imaging;
+using Avalonia.Platform;
 using SkiaSharp;
 
 namespace Avalonia.Skia
@@ -220,9 +220,12 @@ namespace Avalonia.Skia
             switch (m)
             {
                 default:
-                case GradientSpreadMethod.Pad: return SKShaderTileMode.Clamp;
+                case GradientSpreadMethod.Pad:
-                case GradientSpreadMethod.Reflect: return SKShaderTileMode.Mirror;
+                    return SKShaderTileMode.Clamp;
-                case GradientSpreadMethod.Repeat: return SKShaderTileMode.Repeat;
+                case GradientSpreadMethod.Reflect:
+                    return SKShaderTileMode.Mirror;
+                case GradientSpreadMethod.Repeat:
+                    return SKShaderTileMode.Repeat;
             }
         }
 
@@ -231,9 +234,12 @@ namespace Avalonia.Skia
             switch (a)
             {
                 default:
-                case TextAlignment.Left: return SKTextAlign.Left;
+                case TextAlignment.Left:
-                case TextAlignment.Center: return SKTextAlign.Center;
+                    return SKTextAlign.Left;
-                case TextAlignment.Right: return SKTextAlign.Right;
+                case TextAlignment.Center:
+                    return SKTextAlign.Center;
+                case TextAlignment.Right:
+                    return SKTextAlign.Right;
             }
         }
 
@@ -262,9 +268,12 @@ namespace Avalonia.Skia
             switch (a)
             {
                 default:
-                case SKTextAlign.Left: return TextAlignment.Left;
+                case SKTextAlign.Left:
-                case SKTextAlign.Center: return TextAlignment.Center;
+                    return TextAlignment.Left;
-                case SKTextAlign.Right: return TextAlignment.Right;
+                case SKTextAlign.Center:
+                    return TextAlignment.Center;
+                case SKTextAlign.Right:
+                    return TextAlignment.Right;
             }
         }
 
@@ -275,7 +284,18 @@ namespace Avalonia.Skia
                 SKFontStyleSlant.Upright => FontStyle.Normal,
                 SKFontStyleSlant.Italic => FontStyle.Italic,
                 SKFontStyleSlant.Oblique => FontStyle.Oblique,
-                _ => throw new ArgumentOutOfRangeException(nameof (slant), slant, null)
+                _ => throw new ArgumentOutOfRangeException(nameof(slant), slant, null)
+            };
+        }
+
+        public static SKFontStyleSlant ToSkia(this FontStyle style)
+        {
+            return style switch
+            {
+                FontStyle.Normal => SKFontStyleSlant.Upright,
+                FontStyle.Italic => SKFontStyleSlant.Italic,
+                FontStyle.Oblique => SKFontStyleSlant.Oblique,
+                _ => throw new ArgumentOutOfRangeException(nameof(style), style, null)
             };
         }
 

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

@@ -1,7 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Collections.ObjectModel;
-using System.Linq;
 using Avalonia.Fonts.Inter;
 using Avalonia.Headless;
 using Avalonia.Media;
@@ -103,7 +101,7 @@ namespace Avalonia.Skia.UnitTests.Media
             {
                 Assert.True(FontManager.Current.TryGetGlyphTypeface(Typeface.Default, out _));
 
-                for (int i = 0;i < 10; i++)
+                for (int i = 0; i < 10; i++)
                 {
                     FontManager.Current.TryGetGlyphTypeface(new Typeface("Unknown"), out _);
                 }
@@ -313,7 +311,7 @@ namespace Avalonia.Skia.UnitTests.Media
                 {
                     Assert.True(FontManager.Current.TryGetGlyphTypeface(new Typeface("微軟正黑體"), out var glyphTypeface));
 
-                    Assert.Equal("Microsoft JhengHei",glyphTypeface.FamilyName);
+                    Assert.Equal("Microsoft JhengHei", glyphTypeface.FamilyName);
                 }
             }
         }
@@ -325,7 +323,7 @@ namespace Avalonia.Skia.UnitTests.Media
             {
                 using (AvaloniaLocator.EnterScope())
                 {
-                     FontManager.Current.AddFontCollection(new InterFontCollection());
+                    FontManager.Current.AddFontCollection(new InterFontCollection());
 
                     Assert.True(FontManager.Current.TryGetGlyphTypeface(new Typeface("fonts:Inter#Inter"),
                         out var glyphTypeface));
@@ -428,6 +426,33 @@ namespace Avalonia.Skia.UnitTests.Media
             }
         }
 
+
+        [Win32Fact("Windows specific font")]
+        public void Should_Get_Regular_Font_After_Matching_Italic_Font()
+        {
+            using (UnitTestApplication.Start(TestServices.MockPlatformRenderInterface.With(fontManagerImpl: new FontManagerImpl())))
+            {
+                using (AvaloniaLocator.EnterScope())
+                {
+                    Assert.True(FontManager.Current.TryMatchCharacter('こ', FontStyle.Italic, FontWeight.Normal, FontStretch.Normal, null, null, out var italicTypeface));
+
+                    Assert.Equal(FontSimulations.None, italicTypeface.GlyphTypeface.FontSimulations);
+
+                    Assert.Equal("Yu Gothic UI", italicTypeface.GlyphTypeface.FamilyName);
+
+                    Assert.NotEqual(FontStyle.Normal, italicTypeface.Style);
+
+                    Assert.True(FontManager.Current.TryMatchCharacter('こ', FontStyle.Normal, FontWeight.Normal, FontStretch.Normal, null, null, out var regularTypeface));
+
+                    Assert.Equal("Yu Gothic UI", regularTypeface.GlyphTypeface.FamilyName);
+
+                    Assert.Equal(FontStyle.Normal, regularTypeface.Style);
+
+                    Assert.NotEqual(((GlyphTypefaceImpl)italicTypeface.GlyphTypeface).SKTypeface, ((GlyphTypefaceImpl)regularTypeface.GlyphTypeface).SKTypeface);
+                }
+            }
+        }
+
         [Fact]
         public void Should_Fallback_When_Font_Family_Is_Empty()
         {