[POC] Support ttc font format.

osu.Game.Rulesets.Karaoke/Graphics/UserInterfaceV2/FontSelector.cs

@@ -326,6 +326,7 @@ private void load(OsuColour colour)
                         FontFormat.Internal => colour.Gray7,
                         FontFormat.Fnt => colour.Pink,
                         FontFormat.Ttf => colour.Blue,
+                        FontFormat.Ttc => colour.BlueDark,
                         _ => throw new ArgumentOutOfRangeException(nameof(fontFormat))
                     };
 

osu.Game.Rulesets.Karaoke/IO/Stores/TtfGlyphStore.cs

@@ -56,6 +56,7 @@ public TtfGlyphStore(ResourceStore<byte[]> store, string assetName = null)
             Store = new ResourceStore<byte[]>(store);
 
             Store.AddExtension("ttf");
+            Store.AddExtension("ttc");
 
             AssetName = assetName;
 
@@ -73,8 +74,8 @@ public Task LoadFontAsync() => fontLoadTask ??= Task.Factory.StartNew(() =>
                 using (var s = Store.GetStream($@"{AssetName}"))
                 {
                     var fonts = new FontCollection();
-                    var fontFamily = fonts.Add(s);
-                    font = new Font(fontFamily, 1);
+                    var fontFamily = fonts.AddCollection(s, out var description).ToArray();
+                    font = new Font(fontFamily[0], 1);
                 }
 
                 completionSource.SetResult(font);

osu.Game.Rulesets.Karaoke/Skinning/Fonts/FontInfo.cs

@@ -44,5 +44,7 @@ public enum FontFormat
         Fnt,
 
         Ttf,
+
+        Ttc,
     }
 }

osu.Game.Rulesets.Karaoke/Skinning/Fonts/FontManager.cs

@@ -26,7 +26,7 @@ public class FontManager : Component
 
         private Storage storage => host.Storage.GetStorageForDirectory(FONT_BASE_PATH);
 
-        private readonly FontFormat[] supportedFormat = { FontFormat.Fnt, FontFormat.Ttf };
+        private readonly FontFormat[] supportedFormat = { FontFormat.Fnt, FontFormat.Ttf, FontFormat.Ttc };
 
         public readonly BindableList<FontInfo> Fonts = new();
 
@@ -188,6 +188,7 @@ private void removeFontFromList(string path, FontFormat fontFormat)
             {
                 FontFormat.Fnt => getFntGlyphStore(fontName),
                 FontFormat.Ttf => getTtfGlyphStore(fontName),
+                FontFormat.Ttc => getTtcGlyphStore(fontName),
                 FontFormat.Internal or _ => throw new ArgumentOutOfRangeException(nameof(fontFormat))
             };
         }
@@ -216,11 +217,25 @@ private void removeFontFromList(string path, FontFormat fontFormat)
             return new TtfGlyphStore(new ResourceStore<byte[]>(resources), $"{fontName}");
         }
 
+        private TtfGlyphStore? getTtcGlyphStore(string fontName)
+        {
+            string path = Path.Combine(getPathByFontType(FontFormat.Ttc), fontName);
+            string? pathWithExtension = Path.ChangeExtension(path, getExtensionByFontType(FontFormat.Ttc));
+
+            if (!storage.Exists(pathWithExtension))
+                return null;
+
+            // because ttc is just a collection of ttf file, so we can use TtfGlyphStore to read it.
+            var resources = new StorageBackedResourceStore(storage.GetStorageForDirectory(getPathByFontType(FontFormat.Ttc)));
+            return new TtfGlyphStore(new ResourceStore<byte[]>(resources), $"{fontName}");
+        }
+
         private static string getPathByFontType(FontFormat type) =>
             type switch
             {
                 FontFormat.Fnt => "fnt",
                 FontFormat.Ttf => "ttf",
+                FontFormat.Ttc => "ttc",
                 FontFormat.Internal or _ => throw new ArgumentOutOfRangeException(nameof(type))
             };
 
@@ -229,6 +244,7 @@ private static string getExtensionByFontType(FontFormat type) =>
             {
                 FontFormat.Fnt => "zipfnt",
                 FontFormat.Ttf => "ttf",
+                FontFormat.Ttc => "ttc",
                 FontFormat.Internal or _ => throw new ArgumentOutOfRangeException(nameof(type))
             };
 
@@ -237,6 +253,7 @@ private static FontFormat getFontTypeByExtension(string extension) =>
             {
                 ".zipfnt" => FontFormat.Fnt,
                 ".ttf" => FontFormat.Ttf,
+                ".ttc" => FontFormat.Ttc,
                 _ => throw new FormatException(nameof(extension)),
             };