Add high-contrast theme (#149779)

This is to add a high-contrast color scheme when we turn on high-contrast mode. Fixes flutter/flutter#149683

Author: QuncCccccc

dev/a11y_assessments/lib/main.dart

@@ -20,14 +20,25 @@ class App extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    final ThemeData lightTheme = ThemeData(
+      colorScheme: ColorScheme.fromSeed(
+        seedColor: const Color(0xff6750a4),
+        contrastLevel: MediaQuery.highContrastOf(context) ? 1.0 : 0.0,
+    ));
+    final ThemeData darkTheme = ThemeData(
+      colorScheme: ColorScheme.fromSeed(
+        brightness: Brightness.dark,
+        seedColor: const Color(0xff6750a4),
+        contrastLevel: MediaQuery.highContrastOf(context) ? 1.0 : 0.0,
+    ));
 
     final Map<String, WidgetBuilder> routes = Map<String, WidgetBuilder>.fromEntries(
       useCases.map((UseCase useCase) => MapEntry<String, WidgetBuilder>(useCase.route, useCase.build)),
     );
     return MaterialApp(
       title: 'Accessibility Assessments',
-      theme: ThemeData.light(),
-      darkTheme: ThemeData.dark(),
+      theme: lightTheme,
+      darkTheme: darkTheme,
       routes: <String, WidgetBuilder>{
         '/': (_) => const HomePage(),
         ...routes

dev/a11y_assessments/test/home_page_test.dart

@@ -5,6 +5,7 @@
 import 'package:a11y_assessments/main.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:material_color_utilities/material_color_utilities.dart';
 
 
 void main() {
@@ -14,4 +15,67 @@ void main() {
     expect(app.theme!.brightness, equals(Brightness.light));
     expect(app.darkTheme!.brightness, equals(Brightness.dark));
   });
+
+  testWidgets('App can generate high-contrast color scheme', (WidgetTester tester) async {
+    await tester.pumpWidget(const MediaQuery(
+      data: MediaQueryData(
+        highContrast: true,
+      ),
+      child: App()
+    ));
+
+    final MaterialApp app = find.byType(MaterialApp).evaluate().first.widget as MaterialApp;
+
+    final DynamicScheme highContrastScheme = SchemeTonalSpot(sourceColorHct: Hct.fromInt(const Color(0xff6750a4).value), isDark: false, contrastLevel: 1.0);
+    final ColorScheme appScheme = app.theme!.colorScheme;
+
+    expect(appScheme.primary.value, MaterialDynamicColors.primary.getArgb(highContrastScheme));
+    expect(appScheme.onPrimary.value, MaterialDynamicColors.onPrimary.getArgb(highContrastScheme));
+    expect(appScheme.primaryContainer.value, MaterialDynamicColors.primaryContainer.getArgb(highContrastScheme));
+    expect(appScheme.onPrimaryContainer.value, MaterialDynamicColors.onPrimaryContainer.getArgb(highContrastScheme));
+    expect(appScheme.primaryFixed.value, MaterialDynamicColors.primaryFixed.getArgb(highContrastScheme));
+    expect(appScheme.primaryFixedDim.value, MaterialDynamicColors.primaryFixedDim.getArgb(highContrastScheme));
+    expect(appScheme.onPrimaryFixed.value, MaterialDynamicColors.onPrimaryFixed.getArgb(highContrastScheme));
+    expect(appScheme.onPrimaryFixedVariant.value, MaterialDynamicColors.onPrimaryFixedVariant.getArgb(highContrastScheme));
+    expect(appScheme.secondary.value, MaterialDynamicColors.secondary.getArgb(highContrastScheme));
+    expect(appScheme.onSecondary.value, MaterialDynamicColors.onSecondary.getArgb(highContrastScheme));
+    expect(appScheme.secondaryContainer.value, MaterialDynamicColors.secondaryContainer.getArgb(highContrastScheme));
+    expect(appScheme.onSecondaryContainer.value, MaterialDynamicColors.onSecondaryContainer.getArgb(highContrastScheme));
+    expect(appScheme.secondaryFixed.value, MaterialDynamicColors.secondaryFixed.getArgb(highContrastScheme));
+    expect(appScheme.secondaryFixedDim.value, MaterialDynamicColors.secondaryFixedDim.getArgb(highContrastScheme));
+    expect(appScheme.onSecondaryFixed.value, MaterialDynamicColors.onSecondaryFixed.getArgb(highContrastScheme));
+    expect(appScheme.onSecondaryFixedVariant.value, MaterialDynamicColors.onSecondaryFixedVariant.getArgb(highContrastScheme));
+    expect(appScheme.tertiary.value, MaterialDynamicColors.tertiary.getArgb(highContrastScheme));
+    expect(appScheme.onTertiary.value, MaterialDynamicColors.onTertiary.getArgb(highContrastScheme));
+    expect(appScheme.tertiaryContainer.value, MaterialDynamicColors.tertiaryContainer.getArgb(highContrastScheme));
+    expect(appScheme.onTertiaryContainer.value, MaterialDynamicColors.onTertiaryContainer.getArgb(highContrastScheme));
+    expect(appScheme.tertiaryFixed.value, MaterialDynamicColors.tertiaryFixed.getArgb(highContrastScheme));
+    expect(appScheme.tertiaryFixedDim.value, MaterialDynamicColors.tertiaryFixedDim.getArgb(highContrastScheme));
+    expect(appScheme.onTertiaryFixed.value, MaterialDynamicColors.onTertiaryFixed.getArgb(highContrastScheme));
+    expect(appScheme.onTertiaryFixedVariant.value, MaterialDynamicColors.onTertiaryFixedVariant.getArgb(highContrastScheme));
+    expect(appScheme.error.value, MaterialDynamicColors.error.getArgb(highContrastScheme));
+    expect(appScheme.onError.value, MaterialDynamicColors.onError.getArgb(highContrastScheme));
+    expect(appScheme.errorContainer.value, MaterialDynamicColors.errorContainer.getArgb(highContrastScheme));
+    expect(appScheme.onErrorContainer.value, MaterialDynamicColors.onErrorContainer.getArgb(highContrastScheme));
+    expect(appScheme.background.value, MaterialDynamicColors.background.getArgb(highContrastScheme));
+    expect(appScheme.onBackground.value, MaterialDynamicColors.onBackground.getArgb(highContrastScheme));
+    expect(appScheme.surface.value, MaterialDynamicColors.surface.getArgb(highContrastScheme));
+    expect(appScheme.surfaceDim.value, MaterialDynamicColors.surfaceDim.getArgb(highContrastScheme));
+    expect(appScheme.surfaceBright.value, MaterialDynamicColors.surfaceBright.getArgb(highContrastScheme));
+    expect(appScheme.surfaceContainerLowest.value, MaterialDynamicColors.surfaceContainerLowest.getArgb(highContrastScheme));
+    expect(appScheme.surfaceContainerLow.value, MaterialDynamicColors.surfaceContainerLow.getArgb(highContrastScheme));
+    expect(appScheme.surfaceContainer.value, MaterialDynamicColors.surfaceContainer.getArgb(highContrastScheme));
+    expect(appScheme.surfaceContainerHigh.value, MaterialDynamicColors.surfaceContainerHigh.getArgb(highContrastScheme));
+    expect(appScheme.surfaceContainerHighest.value, MaterialDynamicColors.surfaceContainerHighest.getArgb(highContrastScheme));
+    expect(appScheme.onSurface.value, MaterialDynamicColors.onSurface.getArgb(highContrastScheme));
+    expect(appScheme.surfaceVariant.value, MaterialDynamicColors.surfaceVariant.getArgb(highContrastScheme));
+    expect(appScheme.onSurfaceVariant.value, MaterialDynamicColors.onSurfaceVariant.getArgb(highContrastScheme));
+    expect(appScheme.outline.value, MaterialDynamicColors.outline.getArgb(highContrastScheme));
+    expect(appScheme.outlineVariant.value, MaterialDynamicColors.outlineVariant.getArgb(highContrastScheme));
+    expect(appScheme.shadow.value, MaterialDynamicColors.shadow.getArgb(highContrastScheme));
+    expect(appScheme.scrim.value, MaterialDynamicColors.scrim.getArgb(highContrastScheme));
+    expect(appScheme.inverseSurface.value, MaterialDynamicColors.inverseSurface.getArgb(highContrastScheme));
+    expect(appScheme.onInverseSurface.value, MaterialDynamicColors.inverseOnSurface.getArgb(highContrastScheme));
+    expect(appScheme.inversePrimary.value, MaterialDynamicColors.inversePrimary.getArgb(highContrastScheme));
+  });
 }