Enhance ColorScheme.fromSeed with a new variant parameter (#144805)

Fixes #144649

This PR is to add an enhancement for `ColorScheme.fromSeed()`.  When we input a brighter color with a high chroma and we want the resulting `ColorScheme` respects the source color, we can achieve this by setting

```dart
ColorScheme.fromSeed(
  seedColor: sourceColor,
  variant: Variant.fidelity,
  ...
)
```

Here is a demo for `ColorScheme` constructed by all 9 variants:
![Screenshot 2024-03-13 at 4 33 02 PM](https://github.com/flutter/flutter/assets/36861262/2cdbe559-67ff-4f8b-bd48-ccff5131b949)
![Screenshot 2024-03-13 at 4 33 07 PM](https://github.com/flutter/flutter/assets/36861262/e6af2362-c501-499b-8880-06a321de91e6)

examples/api/lib/material/color_scheme/color_scheme.0.dart

@@ -19,43 +19,28 @@ class ColorSchemeExample extends StatefulWidget {
 
 class _ColorSchemeExampleState extends State<ColorSchemeExample> {
   Color selectedColor = ColorSeed.baseColor.color;
+  Brightness selectedBrightness = Brightness.light;
+  static const List<DynamicSchemeVariant> schemeVariants = DynamicSchemeVariant.values;
 
   @override
   Widget build(BuildContext context) {
-    final Color? colorSeed = selectedColor == ColorSeed.baseColor.color ? null : selectedColor;
-    final ThemeData lightTheme = ThemeData(
-      colorSchemeSeed: colorSeed,
-      brightness: Brightness.light,
-    );
-    final ThemeData darkTheme = ThemeData(
-      colorSchemeSeed: colorSeed,
-      brightness: Brightness.dark,
-    );
-
-    Widget schemeLabel(String brightness) {
-      return Padding(
-        padding: const EdgeInsets.symmetric(vertical: 15),
-        child: Text(
-          brightness,
-          style: const TextStyle(fontWeight: FontWeight.bold),
-        ),
-      );
-    }
-
-    Widget schemeView(ThemeData theme) {
-      return Padding(
-        padding: const EdgeInsets.symmetric(horizontal: 15),
-        child: ColorSchemeView(colorScheme: theme.colorScheme),
-      );
-    }
-
     return MaterialApp(
-      theme: ThemeData(colorSchemeSeed: selectedColor),
+      debugShowCheckedModeBanner: false,
+      theme: ThemeData(
+        colorScheme: ColorScheme.fromSeed(
+          seedColor: selectedColor,
+          brightness: selectedBrightness,
+        )
+      ),
       home: Builder(
         builder: (BuildContext context) => Scaffold(
           appBar: AppBar(
             title: const Text('ColorScheme'),
-            leading: MenuAnchor(
+            actions: <Widget>[
+              Row(
+                children: <Widget>[
+                  const Text('Color Seed'),
+                  MenuAnchor(
                     builder: (BuildContext context, MenuController controller, Widget? widget) {
                       return IconButton(
                         icon: Icon(Icons.circle, color: selectedColor),
@@ -83,38 +68,92 @@ class _ColorSchemeExampleState extends State<ColorSchemeExample> {
                       );
                     }),
                   ),
+                ],
+              ),
+            ],
           ),
           body: SingleChildScrollView(
             child: Padding(
               padding: const EdgeInsets.only(top: 5),
               child: Column(
+                crossAxisAlignment: CrossAxisAlignment.start,
                 children: <Widget>[
-                  Row(
+                  Padding(
+                    padding: const EdgeInsets.symmetric(horizontal: 24.0),
+                    child: Row(
                       children: <Widget>[
-                      Expanded(
+                        const Text('Brightness'),
+                        const SizedBox(width: 10),
+                        Switch(
+                          value: selectedBrightness == Brightness.light,
+                          onChanged: (bool value) {
+                            setState(() {
+                              selectedBrightness = value ? Brightness.light : Brightness.dark;
+                            });
+                          },
+                        ),
+                      ],
+                    ),
+                  ),
+                  SingleChildScrollView(
+                    scrollDirection: Axis.horizontal,
+                    child: Row(
+                      children: List<Widget>.generate(schemeVariants.length, (int index) {
+                        return ColorSchemeVariantColumn(
+                          selectedColor: selectedColor,
+                          brightness: selectedBrightness,
+                          schemeVariant: schemeVariants[index],
+                        );
+                      }).toList(),
+                    ),
+                  ),
+                ],
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+}
+
+class ColorSchemeVariantColumn extends StatelessWidget {
+  const ColorSchemeVariantColumn({
+    super.key,
+    this.schemeVariant = DynamicSchemeVariant.tonalSpot,
+    this.brightness = Brightness.light,
+    required this.selectedColor,
+  });
+
+  final DynamicSchemeVariant schemeVariant;
+  final Brightness brightness;
+  final Color selectedColor;
+
+  @override
+  Widget build(BuildContext context) {
+    return ConstrainedBox(
+      constraints: const BoxConstraints.tightFor(width: 250),
       child: Column(
         children: <Widget>[
-                            schemeLabel('Light ColorScheme'),
+          Padding(
-                            schemeView(lightTheme),
+            padding: const EdgeInsets.symmetric(vertical: 15),
-                          ],
+            child: Text(
+              schemeVariant.name == 'tonalSpot' ? '${schemeVariant.name} (Default)' : schemeVariant.name,
+              style: const TextStyle(fontWeight: FontWeight.bold),
             ),
           ),
-                      Expanded(
+          Padding(
-                        child: Column(
+            padding: const EdgeInsets.symmetric(horizontal: 15),
-                          children: <Widget>[
+            child: ColorSchemeView(
-                            schemeLabel('Dark ColorScheme'),
+              colorScheme: ColorScheme.fromSeed(
-                            schemeView(darkTheme),
+                seedColor: selectedColor,
-                          ],
+                brightness: brightness,
+                dynamicSchemeVariant: schemeVariant,
+              ),
             ),
           ),
         ],
-                  ),
+      )
-                ],
-              ),
-            ),
-          ),
-        ),
-      ),
     );
   }
 }
@@ -301,7 +340,10 @@ enum ColorSeed {
   yellow('Yellow', Colors.yellow),
   orange('Orange', Colors.orange),
   deepOrange('Deep Orange', Colors.deepOrange),
-  pink('Pink', Colors.pink);
+  pink('Pink', Colors.pink),
+  brightBlue('Bright Blue',  Color(0xFF0000FF)),
+  brightGreen('Bright Green',  Color(0xFF00FF00)),
+  brightRed('Bright Red',  Color(0xFFFF0000));
 
   const ColorSeed(this.label, this.color);
   final String label;

examples/api/test/material/color_scheme/color_scheme.0_test.dart

@@ -11,10 +11,9 @@ void main() {
     await tester.pumpWidget(
       const example.ColorSchemeExample(),
     );
-    expect(find.text('Light ColorScheme'), findsOneWidget);
+    expect(find.text('tonalSpot (Default)'), findsOneWidget);
-    expect(find.text('Dark ColorScheme'), findsOneWidget);
 
-    expect(find.byType(example.ColorChip), findsNWidgets(86));
+    expect(find.byType(example.ColorChip), findsNWidgets(43 * 9));
   });
 
   testWidgets('Change color seed', (WidgetTester tester) async {
@@ -30,7 +29,7 @@ void main() {
         )
       );
     }
-    expect(coloredBox().color, const Color(0xFF6750A4));
+    expect(coloredBox().color, const Color(0xff65558f));
     await tester.tap(find.byType(MenuAnchor));
     await tester.pumpAndSettle();
     await tester.tap(find.widgetWithText(MenuItemButton, 'Yellow'));

packages/flutter/lib/src/material/color_scheme.dart

@@ -12,6 +12,52 @@ import 'package:material_color_utilities/material_color_utilities.dart';
 import 'colors.dart';
 import 'theme_data.dart';
 
+/// The algorithm used to construct a [ColorScheme] in [ColorScheme.fromSeed].
+///
+/// The `tonalSpot` variant builds default Material scheme colors. These colors are
+/// mapped to light or dark tones to achieve visually accessible color
+/// pairings with sufficient contrast between foreground and background elements.
+///
+/// In some cases, the tones can prevent colors from appearing as intended,
+/// such as when a color is too light to offer enough contrast for accessibility.
+/// Color fidelity (`DynamicSchemeVariant.fidelity`) is a feature that adjusts
+/// tones in these cases to produce the intended visual results without harming
+/// visual contrast.
+enum DynamicSchemeVariant {
+  /// Default for Material theme colors. Builds pastel palettes with a low chroma.
+  tonalSpot,
+
+  /// The resulting color palettes match seed color, even if the seed color
+  /// is very bright (high chroma).
+  fidelity,
+
+  /// All colors are grayscale, no chroma.
+  monochrome,
+
+  /// Close to grayscale, a hint of chroma.
+  neutral,
+
+  /// Pastel colors, high chroma palettes. The primary palette's chroma is at
+  /// maximum. Use `fidelity` instead if tokens should alter their tone to match
+  /// the palette vibrancy.
+  vibrant,
+
+  /// Pastel colors, medium chroma palettes. The primary palette's hue is
+  /// different from the seed color, for variety.
+  expressive,
+
+  /// Almost identical to `fidelity`. Tokens and palettes match the seed color.
+  /// [ColorScheme.primaryContainer] is the seed color, adjusted to ensure
+  /// contrast with surfaces. The tertiary palette is analogue of the seed color.
+  content,
+
+  /// A playful theme - the seed color's hue does not appear in the theme.
+  rainbow,
+
+  /// A playful theme - the seed color's hue does not appear in the theme.
+  fruitSalad,
+}
+
 /// {@template flutter.material.color_scheme.ColorScheme}
 /// A set of 45 colors based on the
 /// [Material spec](https://m3.material.io/styles/color/the-color-system/color-roles)
@@ -215,20 +261,35 @@ class ColorScheme with Diagnosticable {
 
   /// Generate a [ColorScheme] derived from the given `seedColor`.
   ///
-  /// Using the seedColor as a starting point, a set of tonal palettes are
+  /// Using the `seedColor` as a starting point, a set of tonal palettes are
-  /// constructed. These tonal palettes are based on the Material 3 Color
+  /// constructed. By default, the tonal palettes are based on the Material 3
-  /// system and provide all the needed colors for a [ColorScheme]. These
+  /// Color system and provide all of the [ColorScheme] colors. These colors are
-  /// colors are designed to work well together and meet contrast
+  /// designed to work well together and meet contrast requirements for
-  /// requirements for accessibility.
+  /// accessibility.
   ///
   /// If any of the optional color parameters are non-null they will be
   /// used in place of the generated colors for that field in the resulting
   /// color scheme. This allows apps to override specific colors for their
   /// needs.
   ///
-  /// Given the nature of the algorithm, the seedColor may not wind up as
+  /// Given the nature of the algorithm, the `seedColor` may not wind up as
   /// one of the ColorScheme colors.
   ///
+  /// The `dynamicSchemeVariant` parameter creates different types of
+  /// [DynamicScheme]s, which are used to generate different styles of [ColorScheme]s.
+  /// By default, `dynamicSchemeVariant` is set to `tonalSpot`. A [ColorScheme]
+  /// constructed by `dynamicSchemeVariant.tonalSpot` has pastel palettes and
+  /// won't be too "colorful" even if the `seedColor` has a high chroma value.
+  /// If the resulting color scheme is too dark, consider setting `dynamicSchemeVariant`
+  /// to [DynamicSchemeVariant.fidelity], whose palettes match the seed color.
+  ///
+  /// {@tool dartpad}
+  /// This sample shows how to use [ColorScheme.fromSeed] to create dynamic
+  /// color schemes with different [DynamicSchemeVariant]s.
+  ///
+  /// ** See code in examples/api/lib/material/color_scheme/color_scheme.0.dart **
+  /// {@end-tool}
+  ///
   /// See also:
   ///
   ///  * <https://m3.material.io/styles/color/the-color-system/color-roles>, the
@@ -238,6 +299,7 @@ class ColorScheme with Diagnosticable {
   factory ColorScheme.fromSeed({
     required Color seedColor,
     Brightness brightness = Brightness.light,
+    DynamicSchemeVariant dynamicSchemeVariant = DynamicSchemeVariant.tonalSpot,
     Color? primary,
     Color? onPrimary,
     Color? primaryContainer,
@@ -300,13 +362,7 @@ class ColorScheme with Diagnosticable {
     )
     Color? surfaceVariant,
   }) {
-    final SchemeTonalSpot scheme;
+    final DynamicScheme scheme = _buildDynamicScheme(brightness, seedColor, dynamicSchemeVariant);
-    switch (brightness) {
-      case Brightness.light:
-        scheme = SchemeTonalSpot(sourceColorHct: Hct.fromInt(seedColor.value), isDark: false, contrastLevel: 0.0);
-      case Brightness.dark:
-        scheme = SchemeTonalSpot(sourceColorHct: Hct.fromInt(seedColor.value), isDark: true, contrastLevel: 0.0);
-    }
 
     return ColorScheme(
       primary: primary ?? Color(MaterialDynamicColors.primary.getArgb(scheme)),
@@ -1615,6 +1671,7 @@ class ColorScheme with Diagnosticable {
   static Future<ColorScheme> fromImageProvider({
     required ImageProvider provider,
     Brightness brightness = Brightness.light,
+    DynamicSchemeVariant dynamicSchemeVariant = DynamicSchemeVariant.tonalSpot,
     Color? primary,
     Color? onPrimary,
     Color? primaryContainer,
@@ -1688,13 +1745,7 @@ class ColorScheme with Diagnosticable {
     final List<int> scoredResults = Score.score(colorToCount, desired: 1);
     final ui.Color baseColor = Color(scoredResults.first);
 
-    final SchemeTonalSpot scheme;
+    final DynamicScheme scheme = _buildDynamicScheme(brightness, baseColor, dynamicSchemeVariant);
-    switch (brightness) {
-      case Brightness.light:
-        scheme = SchemeTonalSpot(sourceColorHct: Hct.fromInt(baseColor.value), isDark: false, contrastLevel: 0.0);
-      case Brightness.dark:
-        scheme = SchemeTonalSpot(sourceColorHct: Hct.fromInt(baseColor.value), isDark: true, contrastLevel: 0.0);
-    }
 
     return ColorScheme(
       primary: primary ?? Color(MaterialDynamicColors.primary.getArgb(scheme)),
@@ -1830,4 +1881,20 @@ class ColorScheme with Diagnosticable {
     final int b = abgr & onlyBMask;
     return (abgr & exceptRMask & exceptBMask) | (b << 16) | r;
   }
+
+  static DynamicScheme _buildDynamicScheme(Brightness brightness, Color seedColor, DynamicSchemeVariant schemeVariant) {
+    final bool isDark = brightness == Brightness.dark;
+    final Hct sourceColor =  Hct.fromInt(seedColor.value);
+    return switch (schemeVariant) {
+      DynamicSchemeVariant.tonalSpot => SchemeTonalSpot(sourceColorHct: sourceColor, isDark: isDark, contrastLevel: 0.0),
+      DynamicSchemeVariant.fidelity => SchemeFidelity(sourceColorHct: sourceColor, isDark: isDark, contrastLevel: 0.0),
+      DynamicSchemeVariant.content => SchemeContent(sourceColorHct: sourceColor, isDark: isDark, contrastLevel: 0.0),
+      DynamicSchemeVariant.monochrome => SchemeMonochrome(sourceColorHct: sourceColor, isDark: isDark, contrastLevel: 0.0),
+      DynamicSchemeVariant.neutral => SchemeNeutral(sourceColorHct: sourceColor, isDark: isDark, contrastLevel: 0.0),
+      DynamicSchemeVariant.vibrant => SchemeVibrant(sourceColorHct: sourceColor, isDark: isDark, contrastLevel: 0.0),
+      DynamicSchemeVariant.expressive => SchemeExpressive(sourceColorHct: sourceColor, isDark: isDark, contrastLevel: 0.0),
+      DynamicSchemeVariant.rainbow => SchemeRainbow(sourceColorHct: sourceColor, isDark: isDark, contrastLevel: 0.0),
+      DynamicSchemeVariant.fruitSalad => SchemeFruitSalad(sourceColorHct: sourceColor, isDark: isDark, contrastLevel: 0.0),
+    };
+  }
 }

packages/flutter/test/material/color_scheme_test.dart

@@ -2,10 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:typed_data';
 
+import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:material_color_utilities/material_color_utilities.dart';
 
 import '../image_data.dart';
 
@@ -684,4 +685,143 @@ void main() {
   },
     skip: isBrowser, // https://github.com/flutter/flutter/issues/44115
   );
+
+  testWidgets('Color values in ColorScheme.fromSeed with different variants matches values in DynamicScheme', (WidgetTester tester) async {
+    const Color seedColor = Colors.orange;
+    final Hct sourceColor =  Hct.fromInt(seedColor.value);
+    for (final DynamicSchemeVariant schemeVariant in DynamicSchemeVariant.values) {
+      final DynamicScheme dynamicScheme = switch (schemeVariant) {
+        DynamicSchemeVariant.tonalSpot => SchemeTonalSpot(sourceColorHct: sourceColor, isDark: false, contrastLevel: 0.0),
+        DynamicSchemeVariant.fidelity => SchemeFidelity(sourceColorHct: sourceColor, isDark: false, contrastLevel: 0.0),
+        DynamicSchemeVariant.content => SchemeContent(sourceColorHct: sourceColor, isDark: false, contrastLevel: 0.0),
+        DynamicSchemeVariant.monochrome => SchemeMonochrome(sourceColorHct: sourceColor, isDark: false, contrastLevel: 0.0),
+        DynamicSchemeVariant.neutral => SchemeNeutral(sourceColorHct: sourceColor, isDark: false, contrastLevel: 0.0),
+        DynamicSchemeVariant.vibrant => SchemeVibrant(sourceColorHct: sourceColor, isDark: false, contrastLevel: 0.0),
+        DynamicSchemeVariant.expressive => SchemeExpressive(sourceColorHct: sourceColor, isDark: false, contrastLevel: 0.0),
+        DynamicSchemeVariant.rainbow => SchemeRainbow(sourceColorHct: sourceColor, isDark: false, contrastLevel: 0.0),
+        DynamicSchemeVariant.fruitSalad => SchemeFruitSalad(sourceColorHct: sourceColor, isDark: false, contrastLevel: 0.0),
+      };
+      final ColorScheme colorScheme = ColorScheme.fromSeed(
+        seedColor: seedColor,
+        dynamicSchemeVariant: schemeVariant,
+      );
+
+      expect(colorScheme.primary.value, MaterialDynamicColors.primary.getArgb(dynamicScheme));
+      expect(colorScheme.onPrimary.value, MaterialDynamicColors.onPrimary.getArgb(dynamicScheme));
+      expect(colorScheme.primaryContainer.value, MaterialDynamicColors.primaryContainer.getArgb(dynamicScheme));
+      expect(colorScheme.onPrimaryContainer.value, MaterialDynamicColors.onPrimaryContainer.getArgb(dynamicScheme));
+      expect(colorScheme.primaryFixed.value, MaterialDynamicColors.primaryFixed.getArgb(dynamicScheme));
+      expect(colorScheme.primaryFixedDim.value, MaterialDynamicColors.primaryFixedDim.getArgb(dynamicScheme));
+      expect(colorScheme.onPrimaryFixed.value, MaterialDynamicColors.onPrimaryFixed.getArgb(dynamicScheme));
+      expect(colorScheme.onPrimaryFixedVariant.value, MaterialDynamicColors.onPrimaryFixedVariant.getArgb(dynamicScheme));
+      expect(colorScheme.secondary.value, MaterialDynamicColors.secondary.getArgb(dynamicScheme));
+      expect(colorScheme.onSecondary.value, MaterialDynamicColors.onSecondary.getArgb(dynamicScheme));
+      expect(colorScheme.secondaryContainer.value, MaterialDynamicColors.secondaryContainer.getArgb(dynamicScheme));
+      expect(colorScheme.onSecondaryContainer.value, MaterialDynamicColors.onSecondaryContainer.getArgb(dynamicScheme));
+      expect(colorScheme.secondaryFixed.value, MaterialDynamicColors.secondaryFixed.getArgb(dynamicScheme));
+      expect(colorScheme.secondaryFixedDim.value, MaterialDynamicColors.secondaryFixedDim.getArgb(dynamicScheme));
+      expect(colorScheme.onSecondaryFixed.value, MaterialDynamicColors.onSecondaryFixed.getArgb(dynamicScheme));
+      expect(colorScheme.onSecondaryFixedVariant.value, MaterialDynamicColors.onSecondaryFixedVariant.getArgb(dynamicScheme));
+      expect(colorScheme.tertiary.value, MaterialDynamicColors.tertiary.getArgb(dynamicScheme));
+      expect(colorScheme.onTertiary.value, MaterialDynamicColors.onTertiary.getArgb(dynamicScheme));
+      expect(colorScheme.tertiaryContainer.value, MaterialDynamicColors.tertiaryContainer.getArgb(dynamicScheme));
+      expect(colorScheme.onTertiaryContainer.value, MaterialDynamicColors.onTertiaryContainer.getArgb(dynamicScheme));
+      expect(colorScheme.tertiaryFixed.value, MaterialDynamicColors.tertiaryFixed.getArgb(dynamicScheme));
+      expect(colorScheme.tertiaryFixedDim.value, MaterialDynamicColors.tertiaryFixedDim.getArgb(dynamicScheme));
+      expect(colorScheme.onTertiaryFixed.value, MaterialDynamicColors.onTertiaryFixed.getArgb(dynamicScheme));
+      expect(colorScheme.onTertiaryFixedVariant.value, MaterialDynamicColors.onTertiaryFixedVariant.getArgb(dynamicScheme));
+      expect(colorScheme.error.value, MaterialDynamicColors.error.getArgb(dynamicScheme));
+      expect(colorScheme.onError.value, MaterialDynamicColors.onError.getArgb(dynamicScheme));
+      expect(colorScheme.errorContainer.value, MaterialDynamicColors.errorContainer.getArgb(dynamicScheme));
+      expect(colorScheme.onErrorContainer.value, MaterialDynamicColors.onErrorContainer.getArgb(dynamicScheme));
+      expect(colorScheme.background.value, MaterialDynamicColors.background.getArgb(dynamicScheme));
+      expect(colorScheme.onBackground.value, MaterialDynamicColors.onBackground.getArgb(dynamicScheme));
+      expect(colorScheme.surface.value, MaterialDynamicColors.surface.getArgb(dynamicScheme));
+      expect(colorScheme.surfaceDim.value, MaterialDynamicColors.surfaceDim.getArgb(dynamicScheme));
+      expect(colorScheme.surfaceBright.value, MaterialDynamicColors.surfaceBright.getArgb(dynamicScheme));
+      expect(colorScheme.surfaceContainerLowest.value, MaterialDynamicColors.surfaceContainerLowest.getArgb(dynamicScheme));
+      expect(colorScheme.surfaceContainerLow.value, MaterialDynamicColors.surfaceContainerLow.getArgb(dynamicScheme));
+      expect(colorScheme.surfaceContainer.value, MaterialDynamicColors.surfaceContainer.getArgb(dynamicScheme));
+      expect(colorScheme.surfaceContainerHigh.value, MaterialDynamicColors.surfaceContainerHigh.getArgb(dynamicScheme));
+      expect(colorScheme.surfaceContainerHighest.value, MaterialDynamicColors.surfaceContainerHighest.getArgb(dynamicScheme));
+      expect(colorScheme.onSurface.value, MaterialDynamicColors.onSurface.getArgb(dynamicScheme));
+      expect(colorScheme.surfaceVariant.value, MaterialDynamicColors.surfaceVariant.getArgb(dynamicScheme));
+      expect(colorScheme.onSurfaceVariant.value, MaterialDynamicColors.onSurfaceVariant.getArgb(dynamicScheme));
+      expect(colorScheme.outline.value, MaterialDynamicColors.outline.getArgb(dynamicScheme));
+      expect(colorScheme.outlineVariant.value, MaterialDynamicColors.outlineVariant.getArgb(dynamicScheme));
+      expect(colorScheme.shadow.value, MaterialDynamicColors.shadow.getArgb(dynamicScheme));
+      expect(colorScheme.scrim.value, MaterialDynamicColors.scrim.getArgb(dynamicScheme));
+      expect(colorScheme.inverseSurface.value, MaterialDynamicColors.inverseSurface.getArgb(dynamicScheme));
+      expect(colorScheme.onInverseSurface.value, MaterialDynamicColors.inverseOnSurface.getArgb(dynamicScheme));
+      expect(colorScheme.inversePrimary.value, MaterialDynamicColors.inversePrimary.getArgb(dynamicScheme));
+    }
+  });
+
+  testWidgets('ColorScheme.fromSeed with different variants spot checks', (WidgetTester tester) async {
+    // Default (Variant.tonalSpot).
+    await _testFilledButtonColor(tester, ColorScheme.fromSeed(seedColor: const Color(0xFF000000)), const Color(0xFF8C4A60));
+    await _testFilledButtonColor(tester, ColorScheme.fromSeed(seedColor: const Color(0xFF00FF00)), const Color(0xFF406836));
+    await _testFilledButtonColor(tester, ColorScheme.fromSeed(seedColor: const Color(0xFF6559F5)), const Color(0xFF5B5891));
+    await _testFilledButtonColor(tester, ColorScheme.fromSeed(seedColor: const Color(0xFFFFFFFF)), const Color(0xFF006874));
+
+    // Variant.fidelity.
+    await _testFilledButtonColor(
+      tester,
+      ColorScheme.fromSeed(
+        seedColor: const Color(0xFF000000),
+        dynamicSchemeVariant: DynamicSchemeVariant.fidelity
+      ),
+      const Color(0xFF000000)
+    );
+    await _testFilledButtonColor(
+      tester,
+      ColorScheme.fromSeed(
+        seedColor: const Color(0xFF00FF00),
+        dynamicSchemeVariant: DynamicSchemeVariant.fidelity
+      ),
+      const Color(0xFF026E00)
+    );
+    await _testFilledButtonColor(
+      tester,
+      ColorScheme.fromSeed(
+        seedColor: const Color(0xFF6559F5),
+        dynamicSchemeVariant: DynamicSchemeVariant.fidelity
+      ),
+      const Color(0xFF4C3CDB)
+    );
+    await _testFilledButtonColor(
+      tester,
+      ColorScheme.fromSeed(
+        seedColor: const Color(0xFFFFFFFF),
+        dynamicSchemeVariant: DynamicSchemeVariant.fidelity
+      ),
+      const Color(0xFF5D5F5F)
+    );
+  });
+}
+
+Future<void> _testFilledButtonColor(WidgetTester tester, ColorScheme scheme, Color expectation) async {
+  final GlobalKey key = GlobalKey();
+  await tester.pumpWidget(Container()); // reset
+  await tester.pumpWidget(
+    MaterialApp(
+      theme: ThemeData(
+        colorScheme: scheme,
+      ),
+      home: FilledButton(
+        key: key,
+        onPressed: () {},
+        child: const SizedBox.square(dimension: 200),
+      ),
+    ),
+  );
+
+
+  final Finder buttonMaterial = find.descendant(
+    of: find.byType(FilledButton),
+    matching: find.byType(Material),
+  );
+  final Material material = tester.widget<Material>(buttonMaterial);
+
+  expect(material.color, expectation);
 }