Introduce GlyphTypeface.FaceNames (#18392)

Co-authored-by: Julien Lebosquain <julien@lebosquain.net>

src/Avalonia.Base/Media/Fonts/Tables/Name/NameTable.cs

@@ -2,26 +2,25 @@
 // Licensed under the Apache License, Version 2.0.
 // Ported from: https://github.com/SixLabors/Fonts/blob/034a440aece357341fcc6b02db58ffbe153e54ef/src/SixLabors.Fonts
 
+using System.Collections;
 using System.Collections.Generic;
 using System.IO;
+using Avalonia.Utilities;
 
 namespace Avalonia.Media.Fonts.Tables.Name
 {
-    internal class NameTable
+    internal class NameTable : IEnumerable<NameRecord>
     {
         internal const string TableName = "name";
         internal static readonly OpenTypeTag Tag = OpenTypeTag.Parse(TableName);
 
         private readonly NameRecord[] _names;
 
-        internal NameTable(NameRecord[] names, IReadOnlyList<ushort> languages)
+        internal NameTable(NameRecord[] names)
         {
             _names = names;
-            Languages = languages;
         }
 
-        public IReadOnlyList<ushort> Languages { get; }
-
         /// <summary>
         /// Gets the name of the font.
         /// </summary>
@@ -133,22 +132,6 @@ namespace Avalonia.Media.Fonts.Tables.Name
                 }
             }
 
-            //var languageNames = Array.Empty<StringLoader>();
-
-            //if (format == 1)
-            //{
-            //    // Format 1 adds language data.
-            //    var langCount = reader.ReadUInt16();
-            //    languageNames = new StringLoader[langCount];
-
-            //    for (var i = 0; i < langCount; i++)
-            //    {
-            //        languageNames[i] = StringLoader.Create(reader);
-
-            //        strings.Add(languageNames[i]);
-            //    }
-            //}
-
             foreach (var readable in strings)
             {
                 var readableStartOffset = stringOffset + readable.Offset;
@@ -158,22 +141,17 @@ namespace Avalonia.Media.Fonts.Tables.Name
                 readable.LoadValue(reader);
             }
 
-            var cultures = new List<ushort>();
-
-            foreach (var nameRecord in names)
-            {
-                if (nameRecord.NameID != KnownNameIds.FontFamilyName || nameRecord.Platform != PlatformIDs.Windows || nameRecord.LanguageID == 0)
-                {
-                    continue;
-                }
+            return new NameTable(names);
+        }
 
-                if (!cultures.Contains(nameRecord.LanguageID))
-                {
-                    cultures.Add(nameRecord.LanguageID);
-                }
-            }
+        public IEnumerator<NameRecord> GetEnumerator()
+        {
+            return new ImmutableReadOnlyListStructEnumerator<NameRecord>(_names);
+        }
 
-            return new NameTable(names, cultures);
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return GetEnumerator();
         }
     }
 }

src/Avalonia.Base/Media/IGlyphTypeface2.cs

@@ -29,5 +29,11 @@ namespace Avalonia.Media
         /// Gets supported font features.
         /// </summary>
         IReadOnlyList<OpenTypeTag> SupportedFeatures { get; }
+
+        /// <summary>
+        /// Gets the localized face names.
+        /// <para>Keys are culture identifiers.</para>
+        /// </summary>
+        IReadOnlyDictionary<ushort, string> FaceNames { get; }
     }
 }

src/Skia/Avalonia.Skia/GlyphTypefaceImpl.cs

@@ -111,18 +111,45 @@ namespace Avalonia.Skia
 
             if(_nameTable != null)
             {
-                var familyNames = new Dictionary<ushort, string>(_nameTable.Languages.Count);
+                var familyNames = new Dictionary<ushort, string>(1);
+                var faceNames = new Dictionary<ushort, string>(1);
 
-                foreach (var language in _nameTable.Languages)
+                foreach (var nameRecord in _nameTable)
                 {
-                    familyNames.Add(language, _nameTable.FontFamilyName(language));
+                    if(nameRecord.NameID == KnownNameIds.FontFamilyName)
+                    {
+                        if (nameRecord.Platform != PlatformIDs.Windows || nameRecord.LanguageID == 0)
+                        {
+                            continue;
+                        }
+
+                        if (!familyNames.ContainsKey(nameRecord.LanguageID))
+                        {
+                            familyNames[nameRecord.LanguageID] = nameRecord.Value;
+                        }
+                    }
+
+                    if(nameRecord.NameID == KnownNameIds.FontSubfamilyName)
+                    {
+                        if (nameRecord.Platform != PlatformIDs.Windows || nameRecord.LanguageID == 0)
+                        {
+                            continue;
+                        }
+
+                        if (!faceNames.ContainsKey(nameRecord.LanguageID))
+                        {
+                            faceNames[nameRecord.LanguageID] = nameRecord.Value;
+                        }
+                    }
                 }
 
                 FamilyNames = familyNames;
+                FaceNames = faceNames;
             }
             else
             {
                 FamilyNames = new Dictionary<ushort, string> { { (ushort)CultureInfo.InvariantCulture.LCID, FamilyName } };
+                FaceNames = new Dictionary<ushort, string> { { (ushort)CultureInfo.InvariantCulture.LCID, Weight.ToString() } };
             }
         }
 
@@ -130,6 +157,8 @@ namespace Avalonia.Skia
 
         public IReadOnlyDictionary<ushort, string> FamilyNames { get; }
 
+        public IReadOnlyDictionary<ushort, string> FaceNames { get; }
+
         public IReadOnlyList<OpenTypeTag> SupportedFeatures
         {
             get