Framework support for font features in text styles (#33230)

See https://github.com/flutter/flutter/issues/31691

packages/flutter/lib/src/painting/text_style.dart

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:ui' as ui show ParagraphStyle, TextStyle, StrutStyle, lerpDouble, Shadow;
+import 'dart:ui' as ui show ParagraphStyle, TextStyle, StrutStyle, lerpDouble, Shadow, FontFeature;
 
 import 'package:flutter/foundation.dart';
 
@@ -316,6 +316,7 @@ class TextStyle extends Diagnosticable {
     this.foreground,
     this.background,
     this.shadows,
+    this.fontFeatures,
     this.decoration,
     this.decorationColor,
     this.decorationStyle,
@@ -562,6 +563,15 @@ class TextStyle extends Diagnosticable {
   /// equivalent as order produces differing transparency.
   final List<ui.Shadow> shadows;
 
+  /// A list of [FontFeature]s that affect how the font selects glyphs.
+  ///
+  /// Some fonts support multiple variants of how a given character can be
+  /// rendered.  For example, a font might provide both proportional and
+  /// tabular numbers, or it might offer versions of the zero digit with
+  /// and without slashes.  [FontFeature]s can be used to select which of
+  /// these variants will be used for rendering.
+  final List<ui.FontFeature> fontFeatures;
+
   /// Creates a copy of this text style but with the given fields replaced with
   /// the new values.
   ///
@@ -588,6 +598,7 @@ class TextStyle extends Diagnosticable {
     Paint foreground,
     Paint background,
     List<ui.Shadow> shadows,
+    List<ui.FontFeature> fontFeatures,
     TextDecoration decoration,
     Color decorationColor,
     TextDecorationStyle decorationStyle,
@@ -619,6 +630,7 @@ class TextStyle extends Diagnosticable {
       foreground: foreground ?? this.foreground,
       background: background ?? this.background,
       shadows: shadows ?? this.shadows,
+      fontFeatures: fontFeatures ?? this.fontFeatures,
       decoration: decoration ?? this.decoration,
       decorationColor: decorationColor ?? this.decorationColor,
       decorationStyle: decorationStyle ?? this.decorationStyle,
@@ -718,6 +730,7 @@ class TextStyle extends Diagnosticable {
       foreground: foreground,
       background: background,
       shadows: shadows,
+      fontFeatures: fontFeatures,
       decoration: decoration ?? this.decoration,
       decorationColor: decorationColor ?? this.decorationColor,
       decorationStyle: decorationStyle ?? this.decorationStyle,
@@ -776,6 +789,7 @@ class TextStyle extends Diagnosticable {
       foreground: other.foreground,
       background: other.background,
       shadows: other.shadows,
+      fontFeatures: other.fontFeatures,
       decoration: other.decoration,
       decorationColor: other.decorationColor,
       decorationStyle: other.decorationStyle,
@@ -829,6 +843,7 @@ class TextStyle extends Diagnosticable {
         background: t < 0.5 ? null : b.background,
         decoration: t < 0.5 ? null : b.decoration,
         shadows: t < 0.5 ? null : b.shadows,
+        fontFeatures: t < 0.5 ? null : b.fontFeatures,
         decorationColor: Color.lerp(null, b.decorationColor, t),
         decorationStyle: t < 0.5 ? null : b.decorationStyle,
         decorationThickness: t < 0.5 ? null : b.decorationThickness,
@@ -854,6 +869,7 @@ class TextStyle extends Diagnosticable {
         foreground: t < 0.5 ? a.foreground : null,
         background: t < 0.5 ? a.background : null,
         shadows: t < 0.5 ? a.shadows : null,
+        fontFeatures: t < 0.5 ? a.fontFeatures : null,
         decoration: t < 0.5 ? a.decoration : null,
         decorationColor: Color.lerp(a.decorationColor, null, t),
         decorationStyle: t < 0.5 ? a.decorationStyle : null,
@@ -887,6 +903,7 @@ class TextStyle extends Diagnosticable {
           : b.background ?? (Paint()..color = b.backgroundColor)
         : null,
       shadows: t < 0.5 ? a.shadows : b.shadows,
+      fontFeatures: t < 0.5 ? a.fontFeatures : b.fontFeatures,
       decoration: t < 0.5 ? a.decoration : b.decoration,
       decorationColor: Color.lerp(a.decorationColor, b.decorationColor, t),
       decorationStyle: t < 0.5 ? a.decorationStyle : b.decorationStyle,
@@ -919,6 +936,7 @@ class TextStyle extends Diagnosticable {
         : null
       ),
       shadows: shadows,
+      fontFeatures: fontFeatures,
     );
   }
 
@@ -994,6 +1012,7 @@ class TextStyle extends Diagnosticable {
         foreground != other.foreground ||
         background != other.background ||
         !listEquals(shadows, other.shadows) ||
+        !listEquals(fontFeatures, other.fontFeatures) ||
         !listEquals(fontFamilyFallback, other.fontFamilyFallback))
       return RenderComparison.layout;
     if (color != other.color ||
@@ -1032,6 +1051,7 @@ class TextStyle extends Diagnosticable {
            decorationStyle == typedOther.decorationStyle &&
            decorationThickness == typedOther.decorationThickness &&
            listEquals(shadows, typedOther.shadows) &&
+           listEquals(fontFeatures, typedOther.fontFeatures) &&
            listEquals(fontFamilyFallback, typedOther.fontFamilyFallback);
   }
 
@@ -1057,6 +1077,7 @@ class TextStyle extends Diagnosticable {
       decorationColor,
       decorationStyle,
       shadows,
+      fontFeatures,
     );
   }
 

packages/flutter/test/material/theme_test.dart

@@ -719,6 +719,8 @@ class _TextStyleProxy implements TextStyle {
   double get wordSpacing => _delegate.wordSpacing;
   @override
   List<Shadow> get shadows => _delegate.shadows;
+  @override
+  List<ui.FontFeature> get fontFeatures => _delegate.fontFeatures;
 
   @override
   String toString({ DiagnosticLevel minLevel = DiagnosticLevel.debug }) =>
@@ -781,6 +783,7 @@ class _TextStyleProxy implements TextStyle {
     ui.Paint foreground,
     ui.Paint background,
     List<Shadow> shadows,
+    List<ui.FontFeature> fontFeatures,
     TextDecoration decoration,
     Color decorationColor,
     TextDecorationStyle decorationStyle,