perf: web ui loadFontFromList (flutter#181440)

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Optimize the loadFontFromList method of SkiaFontCollection. Reduce the
generation of unnecessary FontMgr.

issue: flutter#181439


## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [ ] I updated/added relevant documentation (doc comments with `///`).
- [ ] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [ ] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

Co-authored-by: Mouad Debbar <mdebbar@google.com>

Author: 2 people

engine/src/flutter/lib/web_ui/lib/src/engine/canvaskit/canvaskit_api.dart

@@ -2114,7 +2114,10 @@ extension type SkFontVariation._(JSObject _) implements JSObject {
   external set value(double? v);
 }
 
-extension type SkTypeface(JSObject _) implements JSObject {}
+extension type SkTypeface(JSObject _) implements JSObject {
+  /// Returns the family name of the typeface.
+  external String? getFamilyName();
+}
 
 @JS('window.flutterCanvasKit.Font')
 extension type SkFont._(JSObject _) implements JSObject {

engine/src/flutter/lib/web_ui/lib/src/engine/canvaskit/fonts.dart

@@ -72,19 +72,20 @@ class SkiaFontCollection implements FlutterFontCollection {
 
   @override
   Future<bool> loadFontFromList(Uint8List list, {String? fontFamily}) async {
-    if (fontFamily == null) {
-      fontFamily = _readActualFamilyName(list);
-      if (fontFamily == null) {
-        printWarning('Failed to read font family name. Aborting font load.');
-        return false;
-      }
-    }
-
     // Make sure CanvasKit is actually loaded
     await renderer.initialize();
 
     final SkTypeface? typeface = canvasKit.Typeface.MakeFreeTypeFaceFromData(list.buffer);
+
     if (typeface != null) {
+      if (fontFamily == null) {
+        // Read actual family name from SkTypeface
+        fontFamily = typeface.getFamilyName();
+        if (fontFamily == null) {
+          printWarning('Failed to read font family name. Aborting font load.');
+          return false;
+        }
+      }
       _registeredFonts.add(RegisteredFont(list, fontFamily, typeface));
       _registerWithFontProvider();
     } else {
@@ -197,13 +198,6 @@ class SkiaFontCollection implements FlutterFontCollection {
     return FontDownloadResult.fromFont(assetName, UnregisteredFont(fontData, url, fontFamily));
   }
 
-  String? _readActualFamilyName(Uint8List bytes) {
-    final SkFontMgr tmpFontMgr = canvasKit.FontMgr.FromData(<Uint8List>[bytes])!;
-    final String? actualFamily = tmpFontMgr.getFamilyName(0);
-    tmpFontMgr.delete();
-    return actualFamily;
-  }
-
   TypefaceFontProvider? _fontProvider;
   SkFontCollection? skFontCollection;