Restore the icon variable-font axes

The SDK now renders Material Symbols from Google's prebuilt SVGs, whose
URLs encode weight, grade, fill and optical size, so fill, weight, grade
and opticalSize on MultiSourceIconModel have a renderer again.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A67XoQYsLVvoMtiKcXXUxY

Author: claude

CHANGELOG.md

@@ -44,6 +44,8 @@
   - `ExpansionTileProperties.showTrailingIcon`, `shape`, `collapsedShape`,
     `cornerRadius`
   - `TextMixin.softWrap`, `textScaleFactor`
+  - `MultiSourceIconModel.fill`, `weight`, `grade`, `opticalSize` (the
+    Material Symbols variable-font axes)
   - `PageViewProperties.allowImplicitScrolling`
 - Document the Flutter replacements for deprecated `cacheExtent`
   (`scrollCacheExtent`) and `Radio.groupValue` (`RadioGroup`).

README.md

@@ -127,7 +127,6 @@ elsewhere:
 | Size and padding parameters such as `ButtonStyle.minimumSize`/`fixedSize`, `InputDecoration.contentPadding` and `TabBar.padding` | The node's own box and `padding` |
 | `ScrollView.clipBehavior` and similar clip parameters | `ClipMixin.clipsContent` |
 | Callbacks and widgets, such as `itemExtentBuilder` and `prototypeItem` | Not representable as JSON; use `itemExtent` |
-| `Icon.fill`/`weight`/`grade`/`opticalSize` | Pending Material Symbols support in the SDK, which renders icons as SVGs |
 
 Defaults follow Material 3. Where a default changed from an earlier
 version, the old value still applies to JSON that omits the key (see

lib/src/api/models/icon.dart

@@ -88,6 +88,25 @@ class MultiSourceIconModel with Equatable, SerializableMixin {
   /// Scale of the image icon.
   final double scale;
 
+  /// Fill for variable icon fonts such as Material Symbols, from 0 (outlined)
+  /// to 1 (filled). Mirrors Flutter's `Icon.fill`.
+  ///
+  /// Renderers that draw Material Symbols from Google's prebuilt SVGs snap
+  /// the axes to the variants those provide.
+  final double? fill;
+
+  /// Stroke weight for variable icon fonts, from 100 to 700. Mirrors
+  /// Flutter's `Icon.weight`.
+  final double? weight;
+
+  /// Grade for variable icon fonts, from -25 to 200. Mirrors Flutter's
+  /// `Icon.grade`.
+  final double? grade;
+
+  /// Optical size for variable icon fonts, from 20 to 48. Mirrors
+  /// Flutter's `Icon.opticalSize`.
+  final double? opticalSize;
+
   /// Whether the type of this icon is image.
   bool get isImageIcon => type == IconTypeEnum.image;
 
@@ -103,6 +122,10 @@ class MultiSourceIconModel with Equatable, SerializableMixin {
     this.size = 24,
     this.color = ColorRGBA.black,
     this.show = true,
+    this.fill,
+    this.weight,
+    this.grade,
+    this.opticalSize,
   }) : type = IconTypeEnum.icon,
        iconImage = null,
        scale = 1,
@@ -117,7 +140,11 @@ class MultiSourceIconModel with Equatable, SerializableMixin {
     this.imageName,
     this.scale = 1,
   }) : type = IconTypeEnum.image,
-       icon = null;
+       icon = null,
+       fill = null,
+       weight = null,
+       grade = null,
+       opticalSize = null;
 
   /// Default constructor of this class.
   const MultiSourceIconModel({
@@ -129,6 +156,10 @@ class MultiSourceIconModel with Equatable, SerializableMixin {
     this.show = false,
     this.imageName,
     this.scale = 1,
+    this.fill,
+    this.weight,
+    this.grade,
+    this.opticalSize,
   });
 
   @override
@@ -141,6 +172,10 @@ class MultiSourceIconModel with Equatable, SerializableMixin {
     show,
     imageName,
     scale,
+    fill,
+    weight,
+    grade,
+    opticalSize,
   ];
 
   /// Duplicates [MultiSourceIconModel] with the given properties overrides.
@@ -159,6 +194,10 @@ class MultiSourceIconModel with Equatable, SerializableMixin {
     bool forceSize = false,
     bool forceIconImage = false,
     bool forceImageName = false,
+    double? fill,
+    double? weight,
+    double? grade,
+    double? opticalSize,
   }) {
     return MultiSourceIconModel(
       iconImage: forceIconImage ? iconImage : (iconImage ?? this.iconImage),
@@ -169,6 +208,10 @@ class MultiSourceIconModel with Equatable, SerializableMixin {
       show: show ?? this.show,
       scale: scale ?? this.scale,
       imageName: forceImageName ? imageName : (imageName ?? this.imageName),
+      fill: fill ?? this.fill,
+      weight: weight ?? this.weight,
+      grade: grade ?? this.grade,
+      opticalSize: opticalSize ?? this.opticalSize,
     );
   }
 

lib/src/api/models/icon.g.dart

@@ -113,6 +113,19 @@ void main() {
   });
 
   group('new Flutter parameters round-trip and stay out of default JSON', () {
+    test('MultiSourceIconModel variable font axes', () {
+      expect(
+        const MultiSourceIconModel.icon().toJson(),
+        isNot(contains('fill')),
+      );
+      const icon = MultiSourceIconModel.icon(fill: 1, weight: 600, grade: 0);
+      final copy = MultiSourceIconModel.fromJson(icon.toJson());
+      expect(copy.fill, 1);
+      expect(copy.weight, 600);
+      expect(copy.grade, 0);
+      expect(copy, isNot(const MultiSourceIconModel.icon(fill: 0)));
+    });
+
     test('TabBarProperties', () {
       final props = TabBarProperties(
         tabAlignment: TabAlignmentC.center,