CupertinoDynamicColor and friends (#37719)

packages/flutter/lib/cupertino.dart

@@ -18,6 +18,7 @@ export 'src/cupertino/colors.dart';
 export 'src/cupertino/date_picker.dart';
 export 'src/cupertino/dialog.dart';
 export 'src/cupertino/icons.dart';
+export 'src/cupertino/interface_level.dart';
 export 'src/cupertino/localizations.dart';
 export 'src/cupertino/nav_bar.dart';
 export 'src/cupertino/page_scaffold.dart';

packages/flutter/lib/src/cupertino/app.dart

@@ -8,6 +8,7 @@ import 'package:flutter/widgets.dart';
 import 'button.dart';
 import 'colors.dart';
 import 'icons.dart';
+import 'interface_level.dart';
 import 'localizations.dart';
 import 'route.dart';
 import 'theme.dart';
@@ -268,45 +269,51 @@ class _CupertinoAppState extends State<CupertinoApp> {
 
     return ScrollConfiguration(
       behavior: _AlwaysCupertinoScrollBehavior(),
-      child: CupertinoTheme(
+      child: CupertinoUserInterfaceLevel(
-        data: effectiveThemeData,
+        data: CupertinoUserInterfaceLevelData.base,
-        child: WidgetsApp(
+        child: CupertinoTheme(
-          key: GlobalObjectKey(this),
+          data: effectiveThemeData,
-          navigatorKey: widget.navigatorKey,
+          child: CupertinoSystemColors(
-          navigatorObservers: _navigatorObservers,
+            data: CupertinoSystemColors.of(context, useFallbackValues: true),
-          pageRouteBuilder: <T>(RouteSettings settings, WidgetBuilder builder) =>
+            child: WidgetsApp(
-            CupertinoPageRoute<T>(settings: settings, builder: builder),
+              key: GlobalObjectKey(this),
-          home: widget.home,
+              navigatorKey: widget.navigatorKey,
-          routes: widget.routes,
+              navigatorObservers: _navigatorObservers,
-          initialRoute: widget.initialRoute,
+              pageRouteBuilder: <T>(RouteSettings settings, WidgetBuilder builder) =>
-          onGenerateRoute: widget.onGenerateRoute,
+                CupertinoPageRoute<T>(settings: settings, builder: builder),
-          onUnknownRoute: widget.onUnknownRoute,
+              home: widget.home,
-          builder: widget.builder,
+              routes: widget.routes,
-          title: widget.title,
+              initialRoute: widget.initialRoute,
-          onGenerateTitle: widget.onGenerateTitle,
+              onGenerateRoute: widget.onGenerateRoute,
-          textStyle: effectiveThemeData.textTheme.textStyle,
+              onUnknownRoute: widget.onUnknownRoute,
-          color: widget.color ?? CupertinoColors.activeBlue,
+              builder: widget.builder,
-          locale: widget.locale,
+              title: widget.title,
-          localizationsDelegates: _localizationsDelegates,
+              onGenerateTitle: widget.onGenerateTitle,
-          localeResolutionCallback: widget.localeResolutionCallback,
+              textStyle: effectiveThemeData.textTheme.textStyle,
-          localeListResolutionCallback: widget.localeListResolutionCallback,
+              color: widget.color ?? CupertinoColors.activeBlue,
-          supportedLocales: widget.supportedLocales,
+              locale: widget.locale,
-          showPerformanceOverlay: widget.showPerformanceOverlay,
+              localizationsDelegates: _localizationsDelegates,
-          checkerboardRasterCacheImages: widget.checkerboardRasterCacheImages,
+              localeResolutionCallback: widget.localeResolutionCallback,
-          checkerboardOffscreenLayers: widget.checkerboardOffscreenLayers,
+              localeListResolutionCallback: widget.localeListResolutionCallback,
-          showSemanticsDebugger: widget.showSemanticsDebugger,
+              supportedLocales: widget.supportedLocales,
-          debugShowCheckedModeBanner: widget.debugShowCheckedModeBanner,
+              showPerformanceOverlay: widget.showPerformanceOverlay,
-          inspectorSelectButtonBuilder: (BuildContext context, VoidCallback onPressed) {
+              checkerboardRasterCacheImages: widget.checkerboardRasterCacheImages,
-            return CupertinoButton.filled(
+              checkerboardOffscreenLayers: widget.checkerboardOffscreenLayers,
-              child: const Icon(
+              showSemanticsDebugger: widget.showSemanticsDebugger,
-                CupertinoIcons.search,
+              debugShowCheckedModeBanner: widget.debugShowCheckedModeBanner,
-                size: 28.0,
+              inspectorSelectButtonBuilder: (BuildContext context, VoidCallback onPressed) {
-                color: CupertinoColors.white,
+                return CupertinoButton.filled(
-              ),
+                  child: const Icon(
-              padding: EdgeInsets.zero,
+                    CupertinoIcons.search,
-              onPressed: onPressed,
+                    size: 28.0,
-            );
+                    color: CupertinoColors.white,
-          },
+                  ),
+                  padding: EdgeInsets.zero,
+                  onPressed: onPressed,
+                );
+              },
+            ),
+          ),
         ),
       ),
     );

packages/flutter/lib/src/cupertino/interface_level.dart

@@ -0,0 +1,76 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import '../widgets/framework.dart';
+
+/// Indicates the visual level for a piece of content. Equivalent to `UIUserInterfaceLevel`
+/// from `UIKit`.
+///
+/// See also:
+///
+/// * `UIUserInterfaceLevel`, the UIKit equivalent: https://developer.apple.com/documentation/uikit/uiuserinterfacelevel.
+enum CupertinoUserInterfaceLevelData {
+  /// The level for your window's main content.
+  base,
+
+  /// The level for content visually above [base].
+  elevated,
+}
+
+/// Establishes a subtree in which [CupertinoUserInterfaceLevel.of] resolves to
+/// the given data.
+///
+/// Querying the current elevation status using [CupertinoUserInterfaceLevel.of]
+/// will cause your widget to rebuild automatically whenever the [CupertinoUserInterfaceLevelData]
+/// changes.
+///
+/// If no [CupertinoUserInterfaceLevel] is in scope then the [CupertinoUserInterfaceLevel.of]
+/// method will throw an exception, unless the `nullOk` argument is set to true,
+/// in which case it returns null.
+///
+/// See also:
+///
+/// * [CupertinoUserInterfaceLevelData], specifies the visual level for the content
+/// in the subtree [CupertinoUserInterfaceLevel] established.
+class CupertinoUserInterfaceLevel extends InheritedWidget {
+  /// Creates a [CupertinoUserInterfaceLevel] to change descendant Cupertino widget's
+  /// visual level.
+  const CupertinoUserInterfaceLevel({
+    Key key,
+    @required CupertinoUserInterfaceLevelData data,
+    Widget child,
+  }) : assert(data != null),
+      _data = data,
+      super(key: key, child: child);
+
+  final CupertinoUserInterfaceLevelData _data;
+
+  @override
+  bool updateShouldNotify(CupertinoUserInterfaceLevel oldWidget) => oldWidget._data != _data;
+
+  /// The data from the closest instance of this class that encloses the given
+  /// context.
+  ///
+  /// You can use this function to query the user interface elevation level within
+  /// the given [BuildContext]. When that information changes, your widget will
+  /// be scheduled to be rebuilt, keeping your widget up-to-date.
+  static CupertinoUserInterfaceLevelData of(BuildContext context, { bool nullOk = false }) {
+    assert(context != null);
+    assert(nullOk != null);
+    final CupertinoUserInterfaceLevel query = context.inheritFromWidgetOfExactType(CupertinoUserInterfaceLevel);
+    if (query != null)
+      return query._data;
+    if (nullOk)
+      return null;
+    throw FlutterError(
+      'CupertinoUserInterfaceLevel.of() called with a context that does not contain a CupertinoUserInterfaceLevel.\n'
+      'No CupertinoUserInterfaceLevel ancestor could be found starting from the context that was passed '
+      'to CupertinoUserInterfaceLevel.of(). This can happen because you do not have a WidgetsApp or '
+      'MaterialApp widget (those widgets introduce a CupertinoUserInterfaceLevel), or it can happen '
+      'if the context you use comes from a widget above those widgets.\n'
+      'The context used was:\n'
+      '  $context'
+    );
+  }
+}

packages/flutter/lib/src/cupertino/slider.dart

@@ -9,6 +9,7 @@ import 'package:flutter/gestures.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
 
+import 'colors.dart';
 import 'theme.dart';
 import 'thumb_painter.dart';
 
@@ -228,7 +229,10 @@ class _CupertinoSliderState extends State<CupertinoSlider> with TickerProviderSt
     return _CupertinoSliderRenderObjectWidget(
       value: (widget.value - widget.min) / (widget.max - widget.min),
       divisions: widget.divisions,
-      activeColor: widget.activeColor ?? CupertinoTheme.of(context).primaryColor,
+      activeColor: CupertinoDynamicColor.resolve(
+        widget.activeColor ?? CupertinoTheme.of(context).primaryColor,
+        context
+      ),
       onChanged: widget.onChanged != null ? _handleChanged : null,
       onChangeStart: widget.onChangeStart != null ? _handleDragStart : null,
       onChangeEnd: widget.onChangeEnd != null ? _handleDragEnd : null,
@@ -257,12 +261,14 @@ class _CupertinoSliderRenderObjectWidget extends LeafRenderObjectWidget {
   final ValueChanged<double> onChangeEnd;
   final TickerProvider vsync;
 
+
   @override
   _RenderCupertinoSlider createRenderObject(BuildContext context) {
     return _RenderCupertinoSlider(
       value: value,
       divisions: divisions,
       activeColor: activeColor,
+      trackColor: CupertinoDynamicColor.resolve(CupertinoSystemColors.of(context).systemFill, context),
       onChanged: onChanged,
       onChangeStart: onChangeStart,
       onChangeEnd: onChangeEnd,
@@ -277,6 +283,7 @@ class _CupertinoSliderRenderObjectWidget extends LeafRenderObjectWidget {
       ..value = value
       ..divisions = divisions
       ..activeColor = activeColor
+      ..trackColor = CupertinoDynamicColor.resolve(CupertinoSystemColors.of(context).systemFill, context)
       ..onChanged = onChanged
       ..onChangeStart = onChangeStart
       ..onChangeEnd = onChangeEnd
@@ -287,7 +294,6 @@ class _CupertinoSliderRenderObjectWidget extends LeafRenderObjectWidget {
 }
 
 const double _kPadding = 8.0;
-const Color _kTrackColor = Color(0xFFB5B5B5);
 const double _kSliderHeight = 2.0 * (CupertinoThumbPainter.radius + _kPadding);
 const double _kSliderWidth = 176.0; // Matches Material Design slider.
 const Duration _kDiscreteTransitionDuration = Duration(milliseconds: 500);
@@ -299,6 +305,7 @@ class _RenderCupertinoSlider extends RenderConstrainedBox {
     @required double value,
     int divisions,
     Color activeColor,
+    Color trackColor,
     ValueChanged<double> onChanged,
     this.onChangeStart,
     this.onChangeEnd,
@@ -309,6 +316,7 @@ class _RenderCupertinoSlider extends RenderConstrainedBox {
        _value = value,
        _divisions = divisions,
        _activeColor = activeColor,
+       _trackColor = trackColor,
        _onChanged = onChanged,
        _textDirection = textDirection,
        super(additionalConstraints: const BoxConstraints.tightFor(width: _kSliderWidth, height: _kSliderHeight)) {
@@ -355,6 +363,15 @@ class _RenderCupertinoSlider extends RenderConstrainedBox {
     markNeedsPaint();
   }
 
+  Color get trackColor => _trackColor;
+  Color _trackColor;
+  set trackColor(Color value) {
+    if (value == _trackColor)
+      return;
+    _trackColor = value;
+    markNeedsPaint();
+  }
+
   ValueChanged<double> get onChanged => _onChanged;
   ValueChanged<double> _onChanged;
   set onChanged(ValueChanged<double> value) {
@@ -468,11 +485,11 @@ class _RenderCupertinoSlider extends RenderConstrainedBox {
       case TextDirection.rtl:
         visualPosition = 1.0 - _position.value;
         leftColor = _activeColor;
-        rightColor = _kTrackColor;
+        rightColor = trackColor;
         break;
       case TextDirection.ltr:
         visualPosition = _position.value;
-        leftColor = _kTrackColor;
+        leftColor = trackColor;
         rightColor = _activeColor;
         break;
     }

packages/flutter/lib/src/cupertino/text_theme.dart

@@ -213,6 +213,32 @@ class CupertinoTextThemeData extends Diagnosticable {
         (_isLight ? _kDefaultDateTimePickerLightTextStyle : _kDefaultDateTimePickerDarkTextStyle);
   }
 
+  /// Returns a copy of the current [CupertinoTextThemeData] with all the colors
+  /// resolved against the given [BuildContext].
+  CupertinoTextThemeData resolveFrom(BuildContext context, { bool nullOk = false }) {
+    Color convertColor(Color color) => color == null ? null : CupertinoDynamicColor.resolve(color, context, nullOk: nullOk);
+
+    TextStyle resolveTextStyle(TextStyle textStyle) {
+      return textStyle?.copyWith(
+        color: convertColor(textStyle.color),
+        backgroundColor: convertColor(textStyle.backgroundColor),
+        decorationColor: convertColor(textStyle.decorationColor),
+      );
+    }
+
+    return copyWith(
+      primaryColor: convertColor(_primaryColor),
+      textStyle: resolveTextStyle(_textStyle),
+      actionTextStyle: resolveTextStyle(_actionTextStyle),
+      tabLabelTextStyle: resolveTextStyle(_tabLabelTextStyle),
+      navTitleTextStyle : resolveTextStyle(_navTitleTextStyle),
+      navLargeTitleTextStyle: resolveTextStyle(_navLargeTitleTextStyle),
+      navActionTextStyle: resolveTextStyle(_navActionTextStyle),
+      pickerTextStyle: resolveTextStyle(_pickerTextStyle),
+      dateTimePickerTextStyle: resolveTextStyle(_dateTimePickerTextStyle),
+    );
+  }
+
   /// Returns a copy of the current [CupertinoTextThemeData] instance with
   /// specified overrides.
   CupertinoTextThemeData copyWith({

packages/flutter/lib/src/cupertino/theme.dart

@@ -54,7 +54,20 @@ class CupertinoTheme extends StatelessWidget {
   /// exist in the ancestry tree.
   static CupertinoThemeData of(BuildContext context) {
     final _InheritedCupertinoTheme inheritedTheme = context.inheritFromWidgetOfExactType(_InheritedCupertinoTheme);
-    return inheritedTheme?.theme?.data ?? const CupertinoThemeData();
+    return (inheritedTheme?.theme?.data ?? const CupertinoThemeData()).resolveFrom(context, nullOk: true);
+  }
+
+  /// Retrieve the [Brightness] value from the closest ancestor [CupertinoTheme]
+  /// widget.
+  ///
+  /// If no ancestral [CupertinoTheme] widget with explicit brightness value could
+  /// be found, the method will resort to the closest ancestor [MediaQuery] widget.
+  ///
+  /// Throws an exception if no such [CupertinoTheme] or [MediaQuery] widgets exist
+  /// in the ancestry tree, unless [nullOk] is set to true.
+  static Brightness brightnessOf(BuildContext context, { bool nullOk = false }) {
+    final _InheritedCupertinoTheme inheritedTheme = context.inheritFromWidgetOfExactType(_InheritedCupertinoTheme);
+    return inheritedTheme?.theme?.data?._brightness ?? MediaQuery.of(context, nullOk: nullOk)?.platformBrightness;
   }
 
   /// The widget below this widget in the tree.
@@ -229,6 +242,23 @@ class CupertinoThemeData extends Diagnosticable {
     );
   }
 
+  /// Return a new `CupertinoThemeData` whose colors are from this `CupertinoThemeData`,
+  /// but resolved aginst the given [BuildContext].
+  ///
+  /// It will be called in [CupertinoTheme.of].
+  @protected
+  CupertinoThemeData resolveFrom(BuildContext context, { bool nullOk = false }) {
+    Color convertColor(Color color) => color == null ? null : CupertinoDynamicColor.resolve(color, context, nullOk: nullOk);
+
+    return copyWith(
+      primaryColor: convertColor(primaryColor),
+      primaryContrastingColor: convertColor(primaryContrastingColor),
+      textTheme: textTheme?.resolveFrom(context, nullOk: nullOk),
+      barBackgroundColor: convertColor(barBackgroundColor),
+      scaffoldBackgroundColor: convertColor(scaffoldBackgroundColor),
+    );
+  }
+
   /// Create a copy of [CupertinoThemeData] with specified attributes overridden.
   ///
   /// Only the current instance's specified attributes are copied instead of
@@ -296,4 +326,39 @@ class _NoDefaultCupertinoThemeData extends CupertinoThemeData {
   final Color barBackgroundColor;
   @override
   final Color scaffoldBackgroundColor;
+
+  @override
+  _NoDefaultCupertinoThemeData resolveFrom(BuildContext context, { bool nullOk = false }) {
+    Color convertColor(Color color) => color == null
+      ? null
+      : CupertinoDynamicColor.resolve(color, context, nullOk: nullOk);
+
+    return _NoDefaultCupertinoThemeData(
+      brightness,
+      convertColor(primaryColor),
+      convertColor(primaryContrastingColor),
+      textTheme?.resolveFrom(context, nullOk: nullOk),
+      convertColor(barBackgroundColor),
+      convertColor(scaffoldBackgroundColor),
+    );
+  }
+
+  @override
+  CupertinoThemeData copyWith({
+    Brightness brightness,
+    Color primaryColor,
+    Color primaryContrastingColor,
+    CupertinoTextThemeData textTheme,
+    Color barBackgroundColor ,
+    Color scaffoldBackgroundColor
+  }) {
+    return _NoDefaultCupertinoThemeData(
+      brightness ?? this.brightness,
+      primaryColor ?? this.primaryColor,
+      primaryContrastingColor ?? this.primaryContrastingColor,
+      textTheme ?? this.textTheme,
+      barBackgroundColor ?? this.barBackgroundColor,
+      scaffoldBackgroundColor ?? this.scaffoldBackgroundColor,
+    );
+  }
 }

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

@@ -1416,34 +1416,43 @@ class MaterialBasedCupertinoThemeData extends CupertinoThemeData {
   ///
   /// The [materialTheme] parameter must not be null.
   MaterialBasedCupertinoThemeData({
-    @required ThemeData materialTheme,
+      @required ThemeData materialTheme,
-  }) : assert(materialTheme != null),
+  }) : this._(
-       _materialTheme = materialTheme,
+    materialTheme,
-       // Pass all values to the superclass so Material-agnostic properties
+    (materialTheme.cupertinoOverrideTheme ?? const CupertinoThemeData()).noDefault(),
-       // like barBackgroundColor can still behave like a normal
+  );
-       // CupertinoThemeData.
+
-       super.raw(
+  MaterialBasedCupertinoThemeData._(
-         materialTheme.cupertinoOverrideTheme?.brightness,
+    this._materialTheme,
-         materialTheme.cupertinoOverrideTheme?.primaryColor,
+    this._cupertinoOverrideTheme,
-         materialTheme.cupertinoOverrideTheme?.primaryContrastingColor,
+  ) : assert(_materialTheme != null),
-         materialTheme.cupertinoOverrideTheme?.textTheme,
+      assert(_cupertinoOverrideTheme != null),
-         materialTheme.cupertinoOverrideTheme?.barBackgroundColor,
+      // Pass all values to the superclass so Material-agnostic properties
-         materialTheme.cupertinoOverrideTheme?.scaffoldBackgroundColor,
+      // like barBackgroundColor can still behave like a normal
-       );
+      // CupertinoThemeData.
+      super.raw(
+        _cupertinoOverrideTheme.brightness,
+        _cupertinoOverrideTheme.primaryColor,
+        _cupertinoOverrideTheme.primaryContrastingColor,
+        _cupertinoOverrideTheme.textTheme,
+        _cupertinoOverrideTheme.barBackgroundColor,
+        _cupertinoOverrideTheme.scaffoldBackgroundColor,
+      );
 
   final ThemeData _materialTheme;
+  final CupertinoThemeData _cupertinoOverrideTheme;
 
   @override
-  Brightness get brightness => _materialTheme.cupertinoOverrideTheme?.brightness ?? _materialTheme.brightness;
+  Brightness get brightness => _cupertinoOverrideTheme.brightness ?? _materialTheme.brightness;
 
   @override
-  Color get primaryColor => _materialTheme.cupertinoOverrideTheme?.primaryColor ?? _materialTheme.colorScheme.primary;
+  Color get primaryColor => _cupertinoOverrideTheme.primaryColor ?? _materialTheme.colorScheme.primary;
 
   @override
-  Color get primaryContrastingColor => _materialTheme.cupertinoOverrideTheme?.primaryContrastingColor ?? _materialTheme.colorScheme.onPrimary;
+  Color get primaryContrastingColor => _cupertinoOverrideTheme.primaryContrastingColor ?? _materialTheme.colorScheme.onPrimary;
 
   @override
-  Color get scaffoldBackgroundColor => _materialTheme.cupertinoOverrideTheme?.scaffoldBackgroundColor ?? _materialTheme.scaffoldBackgroundColor;
+  Color get scaffoldBackgroundColor => _cupertinoOverrideTheme.scaffoldBackgroundColor ?? _materialTheme.scaffoldBackgroundColor;
 
   /// Copies the [ThemeData]'s `cupertinoOverrideTheme`.
   ///
@@ -1457,7 +1466,7 @@ class MaterialBasedCupertinoThemeData extends CupertinoThemeData {
   /// new Material [Theme] and use `copyWith` on the Material [ThemeData]
   /// instead.
   @override
-  CupertinoThemeData copyWith({
+  MaterialBasedCupertinoThemeData copyWith({
     Brightness brightness,
     Color primaryColor,
     Color primaryContrastingColor,
@@ -1465,20 +1474,26 @@ class MaterialBasedCupertinoThemeData extends CupertinoThemeData {
     Color barBackgroundColor,
     Color scaffoldBackgroundColor,
   }) {
-    return _materialTheme.cupertinoOverrideTheme?.copyWith(
+    return MaterialBasedCupertinoThemeData._(
-      brightness: brightness,
+      _materialTheme,
-      primaryColor: primaryColor,
+      _cupertinoOverrideTheme.copyWith(
-      primaryContrastingColor: primaryContrastingColor,
+        brightness: brightness,
-      textTheme: textTheme,
+        primaryColor: primaryColor,
-      barBackgroundColor: barBackgroundColor,
+        primaryContrastingColor: primaryContrastingColor,
-      scaffoldBackgroundColor: scaffoldBackgroundColor,
+        textTheme: textTheme,
-    ) ?? CupertinoThemeData(
+        barBackgroundColor: barBackgroundColor,
-      brightness: brightness,
+        scaffoldBackgroundColor: scaffoldBackgroundColor,
-      primaryColor: primaryColor,
+      ),
-      primaryContrastingColor: primaryContrastingColor,
+    );
-      textTheme: textTheme,
+  }
-      barBackgroundColor: barBackgroundColor,
+
-      scaffoldBackgroundColor: scaffoldBackgroundColor,
+  @override
+  CupertinoThemeData resolveFrom(BuildContext context, { bool nullOk = false }) {
+    // Only the cupertino override theme part will be resolved.
+    // If the color comes from the material theme it's not resolved.
+    return MaterialBasedCupertinoThemeData._(
+      _materialTheme,
+      _cupertinoOverrideTheme.resolveFrom(context, nullOk: nullOk),
     );
   }
 }

packages/flutter/lib/src/widgets/media_query.dart

@@ -98,6 +98,7 @@ class MediaQueryData {
     this.alwaysUse24HourFormat = false,
     this.accessibleNavigation = false,
     this.invertColors = false,
+    this.highContrast = false,
     this.disableAnimations = false,
     this.boldText = false,
   });
@@ -121,6 +122,7 @@ class MediaQueryData {
       invertColors = window.accessibilityFeatures.invertColors,
       disableAnimations = window.accessibilityFeatures.disableAnimations,
       boldText = window.accessibilityFeatures.boldText,
+      highContrast = false,
       alwaysUse24HourFormat = window.alwaysUse24HourFormat;
 
   /// The size of the media in logical pixels (e.g, the size of the screen).
@@ -259,6 +261,13 @@ class MediaQueryData {
   ///  * [Window.AccessibilityFeatures], where the setting originates.
   final bool invertColors;
 
+  /// Whether the user requested a high contrast between foreground and background
+  /// content on iOS, via Settings -> Accessibility -> Increase Contrast.
+  ///
+  /// This flag is currently only updated on iOS devices that are running iOS 13
+  /// or above.
+  final bool highContrast;
+
   /// Whether the platform is requesting that animations be disabled or reduced
   /// as much as possible.
   ///
@@ -293,6 +302,7 @@ class MediaQueryData {
     EdgeInsets viewInsets,
     double physicalDepth,
     bool alwaysUse24HourFormat,
+    bool highContrast,
     bool disableAnimations,
     bool invertColors,
     bool accessibleNavigation,
@@ -309,6 +319,7 @@ class MediaQueryData {
       physicalDepth: physicalDepth ?? this.physicalDepth,
       alwaysUse24HourFormat: alwaysUse24HourFormat ?? this.alwaysUse24HourFormat,
       invertColors: invertColors ?? this.invertColors,
+      highContrast: highContrast ?? this.highContrast,
       disableAnimations: disableAnimations ?? this.disableAnimations,
       accessibleNavigation: accessibleNavigation ?? this.accessibleNavigation,
       boldText: boldText ?? this.boldText,
@@ -357,6 +368,7 @@ class MediaQueryData {
       ),
       viewInsets: viewInsets,
       alwaysUse24HourFormat: alwaysUse24HourFormat,
+      highContrast: highContrast,
       disableAnimations: disableAnimations,
       invertColors: invertColors,
       accessibleNavigation: accessibleNavigation,
@@ -404,6 +416,7 @@ class MediaQueryData {
         bottom: removeBottom ? 0.0 : null,
       ),
       alwaysUse24HourFormat: alwaysUse24HourFormat,
+      highContrast: highContrast,
       disableAnimations: disableAnimations,
       invertColors: invertColors,
       accessibleNavigation: accessibleNavigation,
@@ -451,6 +464,7 @@ class MediaQueryData {
         bottom: removeBottom ? 0.0 : null,
       ),
       alwaysUse24HourFormat: alwaysUse24HourFormat,
+      highContrast: highContrast,
       disableAnimations: disableAnimations,
       invertColors: invertColors,
       accessibleNavigation: accessibleNavigation,
@@ -472,6 +486,7 @@ class MediaQueryData {
         && typedOther.viewInsets == viewInsets
         && typedOther.physicalDepth == physicalDepth
         && typedOther.alwaysUse24HourFormat == alwaysUse24HourFormat
+        && typedOther.highContrast == highContrast
         && typedOther.disableAnimations == disableAnimations
         && typedOther.invertColors == invertColors
         && typedOther.accessibleNavigation == accessibleNavigation
@@ -490,6 +505,7 @@ class MediaQueryData {
       viewInsets,
       physicalDepth,
       alwaysUse24HourFormat,
+      highContrast,
       disableAnimations,
       invertColors,
       accessibleNavigation,
@@ -510,6 +526,7 @@ class MediaQueryData {
              'physicalDepth: $physicalDepth, '
              'alwaysUse24HourFormat: $alwaysUse24HourFormat, '
              'accessibleNavigation: $accessibleNavigation, '
+             'highContrast: $highContrast,'
              'disableAnimations: $disableAnimations, '
              'invertColors: $invertColors, '
              'boldText: $boldText'

packages/flutter/test/cupertino/colors_test.dart

@@ -0,0 +1,748 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/cupertino.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:flutter/rendering.dart';
+
+import '../rendering/mock_canvas.dart';
+
+class DependentWidget extends StatelessWidget {
+  const DependentWidget({
+    Key key,
+    this.color
+  }) : super(key: key);
+
+  final Color color;
+
+  @override
+  Widget build(BuildContext context) {
+    final Color resolved = CupertinoDynamicColor.resolve(color, context);
+    return DecoratedBox(
+      decoration: BoxDecoration(color: resolved),
+      child: const SizedBox.expand(),
+    );
+  }
+}
+
+const Color color0 = Color(0xFF000000);
+const Color color1 = Color(0xFF000001);
+const Color color2 = Color(0xFF000002);
+const Color color3 = Color(0xFF000003);
+const Color color4 = Color(0xFF000004);
+const Color color5 = Color(0xFF000005);
+const Color color6 = Color(0xFF000006);
+const Color color7 = Color(0xFF000007);
+
+// A color that depends on color vibrancy, accessibility contrast, as well as user
+// interface elevation.
+final CupertinoDynamicColor dynamicColor = CupertinoDynamicColor(
+  color: color0,
+  darkColor: color1,
+  elevatedColor: color2,
+  highContrastColor: color3,
+  darkElevatedColor: color4,
+  darkHighContrastColor: color5,
+  highContrastElevatedColor: color6,
+  darkHighContrastElevatedColor: color7,
+);
+
+// A color that uses [color0] in every circumstance.
+final Color notSoDynamicColor1 = CupertinoDynamicColor(
+  color: color0,
+  darkColor: color0,
+  darkHighContrastColor: color0,
+  darkElevatedColor: color0,
+  darkHighContrastElevatedColor: color0,
+  highContrastColor: color0,
+  highContrastElevatedColor: color0,
+  elevatedColor: color0,
+);
+
+// A color that uses [color1] for light mode, and [color0] for dark mode.
+final Color vibrancyDependentColor1 = CupertinoDynamicColor(
+  color: color1,
+  elevatedColor: color1,
+  highContrastColor: color1,
+  highContrastElevatedColor: color1,
+  darkColor: color0,
+  darkHighContrastColor: color0,
+  darkElevatedColor: color0,
+  darkHighContrastElevatedColor: color0,
+);
+
+// A color that uses [color1] for normal contrast mode, and [color0] for high
+// contrast mode.
+final Color contrastDependentColor1 = CupertinoDynamicColor(
+  color: color1,
+  darkColor: color1,
+  elevatedColor: color1,
+  darkElevatedColor: color1,
+  highContrastColor: color0,
+  darkHighContrastColor: color0,
+  highContrastElevatedColor: color0,
+  darkHighContrastElevatedColor: color0,
+);
+
+// A color that uses [color1] for base interface elevation, and [color0] for elevated
+// interface elevation.
+final Color elevationDependentColor1 = CupertinoDynamicColor(
+  color: color1,
+  darkColor: color1,
+  highContrastColor: color1,
+  darkHighContrastColor: color1,
+  elevatedColor: color0,
+  darkElevatedColor: color0,
+  highContrastElevatedColor: color0,
+  darkHighContrastElevatedColor: color0,
+);
+
+void main() {
+  test('== works as expected', () {
+    expect(dynamicColor, CupertinoDynamicColor(
+        color: color0,
+        darkColor: color1,
+        elevatedColor: color2,
+        highContrastColor: color3,
+        darkElevatedColor: color4,
+        darkHighContrastColor: color5,
+        highContrastElevatedColor: color6,
+        darkHighContrastElevatedColor: color7,
+      )
+    );
+
+    expect(notSoDynamicColor1, isNot(vibrancyDependentColor1));
+
+    expect(notSoDynamicColor1, isNot(contrastDependentColor1));
+
+    expect(vibrancyDependentColor1, isNot(CupertinoDynamicColor(
+      color: color0,
+      elevatedColor: color0,
+      highContrastColor: color0,
+      highContrastElevatedColor: color0,
+      darkColor: color0,
+      darkHighContrastColor: color0,
+      darkElevatedColor: color0,
+      darkHighContrastElevatedColor: color0,
+    )));
+  });
+
+  test('CupertinoDynamicColor.toString() works', () {
+    expect(
+      dynamicColor.toString(),
+      'CupertinoDynamicColor(*color = Color(0xff000000)*, '
+      'darkColor = Color(0xff000001), '
+      'highContrastColor = Color(0xff000003), '
+      'darkHighContrastColor = Color(0xff000005), '
+      'elevatedColor = Color(0xff000002), '
+      'darkElevatedColor = Color(0xff000004), '
+      'highContrastElevatedColor = Color(0xff000006), '
+      'darkHighContrastElevatedColor = Color(0xff000007))'
+    );
+    expect(notSoDynamicColor1.toString(), 'CupertinoDynamicColor(*color = Color(0xff000000)*)');
+    expect(vibrancyDependentColor1.toString(), 'CupertinoDynamicColor(*color = Color(0xff000001)*, darkColor = Color(0xff000000))');
+    expect(contrastDependentColor1.toString(), 'CupertinoDynamicColor(*color = Color(0xff000001)*, highContrastColor = Color(0xff000000))');
+    expect(elevationDependentColor1.toString(), 'CupertinoDynamicColor(*color = Color(0xff000001)*, elevatedColor = Color(0xff000000))');
+
+    expect(
+      CupertinoDynamicColor.withBrightnessAndContrast(
+        color: color0,
+        darkColor: color1,
+        highContrastColor: color2,
+        darkHighContrastColor: color3,
+      ).toString(),
+      'CupertinoDynamicColor(*color = Color(0xff000000)*, '
+      'darkColor = Color(0xff000001), '
+      'highContrastColor = Color(0xff000002), '
+      'darkHighContrastColor = Color(0xff000003))',
+    );
+  });
+
+  test('withVibrancy constructor creates colors that may depend on vibrancy', () {
+    expect(vibrancyDependentColor1, CupertinoDynamicColor.withBrightness(
+      color: color1,
+      darkColor: color0,
+    ));
+  });
+
+  test('withVibrancyAndContrast constructor creates colors that may depend on contrast and vibrancy', () {
+    expect(contrastDependentColor1, CupertinoDynamicColor.withBrightnessAndContrast(
+      color: color1,
+      darkColor: color1,
+      highContrastColor: color0,
+      darkHighContrastColor: color0,
+    ));
+
+    expect(CupertinoDynamicColor(
+        color: color0,
+        darkColor: color1,
+        highContrastColor: color2,
+        darkHighContrastColor: color3,
+        elevatedColor: color0,
+        darkElevatedColor: color1,
+        highContrastElevatedColor: color2,
+        darkHighContrastElevatedColor: color3,
+      ),
+      CupertinoDynamicColor.withBrightnessAndContrast(
+        color: color0,
+        darkColor: color1,
+        highContrastColor: color2,
+        darkHighContrastColor: color3,
+    ));
+  });
+
+  testWidgets('Dynamic colors that are not actually dynamic should not claim dependencies',
+    (WidgetTester tester) async {
+      await tester.pumpWidget(DependentWidget(color: notSoDynamicColor1));
+
+      expect(tester.takeException(), null);
+      expect(find.byType(DependentWidget), paints..rect(color: color0));
+  });
+
+  testWidgets(
+    'Dynamic colors that are only dependent on vibrancy should not claim unnecessary dependencies, '
+    'and its resolved color should change when its dependency changes',
+    (WidgetTester tester) async {
+      await tester.pumpWidget(
+        MediaQuery(
+          data: const MediaQueryData(platformBrightness: Brightness.light),
+          child: DependentWidget(color: vibrancyDependentColor1),
+        ),
+      );
+
+      expect(tester.takeException(), null);
+      expect(find.byType(DependentWidget), paints..rect(color: color1));
+      expect(find.byType(DependentWidget), isNot(paints..rect(color: color0)));
+
+      // Changing color vibrancy works.
+      await tester.pumpWidget(
+        MediaQuery(
+          data: const MediaQueryData(platformBrightness: Brightness.dark),
+          child: DependentWidget(color: vibrancyDependentColor1),
+        ),
+      );
+
+      expect(tester.takeException(), null);
+      expect(find.byType(DependentWidget), paints..rect(color: color0));
+      expect(find.byType(DependentWidget), isNot(paints..rect(color: color1)));
+
+      // CupertinoTheme should take percedence over MediaQuery.
+      await tester.pumpWidget(
+        CupertinoTheme(
+          data: const CupertinoThemeData(brightness: Brightness.light),
+          child: MediaQuery(
+            data: const MediaQueryData(platformBrightness: Brightness.dark),
+            child: DependentWidget(color: vibrancyDependentColor1),
+          ),
+        ),
+      );
+
+      expect(tester.takeException(), null);
+      expect(find.byType(DependentWidget), paints..rect(color: color1));
+      expect(find.byType(DependentWidget), isNot(paints..rect(color: color0)));
+  });
+
+  testWidgets(
+    'Dynamic colors that are only dependent on accessibility contrast should not claim unnecessary dependencies, '
+    'and its resolved color should change when its dependency changes',
+    (WidgetTester tester) async {
+      await tester.pumpWidget(
+        MediaQuery(
+          data: const MediaQueryData(highContrast: false),
+          child: DependentWidget(color: contrastDependentColor1),
+        ),
+      );
+
+      expect(tester.takeException(), null);
+      expect(find.byType(DependentWidget), paints..rect(color: color1));
+      expect(find.byType(DependentWidget), isNot(paints..rect(color: color0)));
+
+      // Changing accessibility contrast works.
+      await tester.pumpWidget(
+        MediaQuery(
+          data: const MediaQueryData(highContrast: true),
+          child: DependentWidget(color: contrastDependentColor1),
+        ),
+      );
+
+      expect(tester.takeException(), null);
+      expect(find.byType(DependentWidget), paints..rect(color: color0));
+      expect(find.byType(DependentWidget), isNot(paints..rect(color: color1)));
+
+      // Asserts when the required dependency is missing.
+      await tester.pumpWidget(DependentWidget(color: contrastDependentColor1));
+      expect(tester.takeException()?.toString(), contains('does not contain a MediaQuery'));
+  });
+
+  testWidgets(
+    'Dynamic colors that are only dependent on elevation level should not claim unnecessary dependencies, '
+    'and its resolved color should change when its dependency changes',
+    (WidgetTester tester) async {
+      await tester.pumpWidget(
+        CupertinoUserInterfaceLevel(
+          data: CupertinoUserInterfaceLevelData.base,
+          child: DependentWidget(color: elevationDependentColor1),
+        ),
+      );
+
+      expect(tester.takeException(), null);
+      expect(find.byType(DependentWidget), paints..rect(color: color1));
+      expect(find.byType(DependentWidget), isNot(paints..rect(color: color0)));
+
+      // Changing UI elevation works.
+      await tester.pumpWidget(
+        CupertinoUserInterfaceLevel(
+          data: CupertinoUserInterfaceLevelData.elevated,
+          child: DependentWidget(color: elevationDependentColor1),
+        ),
+      );
+
+      expect(tester.takeException(), null);
+      expect(find.byType(DependentWidget), paints..rect(color: color0));
+      expect(find.byType(DependentWidget), isNot(paints..rect(color: color1)));
+
+      // Asserts when the required dependency is missing.
+      await tester.pumpWidget(DependentWidget(color: elevationDependentColor1));
+      expect(tester.takeException()?.toString(), contains('does not contain a CupertinoUserInterfaceLevel'));
+  });
+
+  testWidgets('Dynamic color with all 3 depedencies works', (WidgetTester tester) async {
+    final Color dynamicRainbowColor1 = CupertinoDynamicColor(
+      color: color0,
+      darkColor: color1,
+      highContrastColor: color2,
+      darkHighContrastColor: color3,
+      darkElevatedColor: color4,
+      highContrastElevatedColor: color5,
+      darkHighContrastElevatedColor: color6,
+      elevatedColor: color7,
+    );
+
+    await tester.pumpWidget(
+      MediaQuery(
+        data: const MediaQueryData(platformBrightness: Brightness.light, highContrast: false),
+        child: CupertinoUserInterfaceLevel(
+          data: CupertinoUserInterfaceLevelData.base,
+          child: DependentWidget(color: dynamicRainbowColor1),
+        ),
+      ),
+    );
+    expect(find.byType(DependentWidget), paints..rect(color: color0));
+
+    await tester.pumpWidget(
+      MediaQuery(
+        data: const MediaQueryData(platformBrightness: Brightness.dark, highContrast: false),
+        child: CupertinoUserInterfaceLevel(
+          data: CupertinoUserInterfaceLevelData.base,
+          child: DependentWidget(color: dynamicRainbowColor1),
+        ),
+      ),
+    );
+    expect(find.byType(DependentWidget), paints..rect(color: color1));
+
+    await tester.pumpWidget(
+      MediaQuery(
+        data: const MediaQueryData(platformBrightness: Brightness.light, highContrast: true),
+        child: CupertinoUserInterfaceLevel(
+          data: CupertinoUserInterfaceLevelData.base,
+          child: DependentWidget(color: dynamicRainbowColor1),
+        ),
+      ),
+    );
+    expect(find.byType(DependentWidget), paints..rect(color: color2));
+
+    await tester.pumpWidget(
+      MediaQuery(
+        data: const MediaQueryData(platformBrightness: Brightness.dark, highContrast: true),
+        child: CupertinoUserInterfaceLevel(
+          data: CupertinoUserInterfaceLevelData.base,
+          child: DependentWidget(color: dynamicRainbowColor1),
+        ),
+      ),
+    );
+    expect(find.byType(DependentWidget), paints..rect(color: color3));
+
+    await tester.pumpWidget(
+      MediaQuery(
+        data: const MediaQueryData(platformBrightness: Brightness.dark, highContrast: false),
+        child: CupertinoUserInterfaceLevel(
+          data: CupertinoUserInterfaceLevelData.elevated,
+          child: DependentWidget(color: dynamicRainbowColor1),
+        ),
+      ),
+    );
+    expect(find.byType(DependentWidget), paints..rect(color: color4));
+
+    await tester.pumpWidget(
+      MediaQuery(
+        data: const MediaQueryData(platformBrightness: Brightness.light, highContrast: true),
+        child: CupertinoUserInterfaceLevel(
+          data: CupertinoUserInterfaceLevelData.elevated,
+          child: DependentWidget(color: dynamicRainbowColor1),
+        ),
+      ),
+    );
+    expect(find.byType(DependentWidget), paints..rect(color: color5));
+
+    await tester.pumpWidget(
+      MediaQuery(
+        data: const MediaQueryData(platformBrightness: Brightness.dark, highContrast: true),
+        child: CupertinoUserInterfaceLevel(
+          data: CupertinoUserInterfaceLevelData.elevated,
+          child: DependentWidget(color: dynamicRainbowColor1),
+        ),
+      ),
+    );
+    expect(find.byType(DependentWidget), paints..rect(color: color6));
+
+    await tester.pumpWidget(
+      MediaQuery(
+        data: const MediaQueryData(platformBrightness: Brightness.light, highContrast: false),
+        child: CupertinoUserInterfaceLevel(
+          data: CupertinoUserInterfaceLevelData.elevated,
+          child: DependentWidget(color: dynamicRainbowColor1),
+        ),
+      ),
+    );
+    expect(find.byType(DependentWidget), paints..rect(color: color7));
+  });
+
+  group('CupertinoSystemColors widget', () {
+    CupertinoSystemColorsData colors;
+    setUp(() { colors = null; });
+
+    Widget systemColorGetter(BuildContext context) {
+      colors = CupertinoSystemColors.of(context);
+      return const Placeholder();
+    }
+
+    testWidgets('exists in CupertinoApp', (WidgetTester tester) async {
+      await tester.pumpWidget(CupertinoApp(home: Builder(builder: systemColorGetter)));
+      expect(colors.systemBackground, CupertinoSystemColors.fallbackValues.systemBackground);
+    });
+
+    testWidgets('resolves against its own BuildContext', (WidgetTester tester) async {
+      await tester.pumpWidget(
+        CupertinoApp(
+          theme: const CupertinoThemeData(brightness: Brightness.dark),
+          home: CupertinoUserInterfaceLevel(
+            data: CupertinoUserInterfaceLevelData.elevated,
+            child: Builder(
+              builder: (BuildContext context) {
+                return CupertinoSystemColors(
+                  child: Builder(builder: systemColorGetter),
+                  data: CupertinoSystemColors.of(context).resolveColors(context),
+                );
+              },
+            ),
+          ),
+        ),
+      );
+
+      // In widget tests the OS colors should fallback to `fallbackValues`.
+      expect(colors.systemBackground, isNot(CupertinoSystemColors.fallbackValues.systemBackground));
+      expect(colors.systemBackground.value, CupertinoSystemColors.fallbackValues.systemBackground.darkElevatedColor.value);
+
+      colors = null;
+      // Changing dependencies works.
+      await tester.pumpWidget(
+        CupertinoApp(
+          theme: const CupertinoThemeData(brightness: Brightness.light),
+          home: Builder(
+            builder: (BuildContext context) {
+              return CupertinoUserInterfaceLevel(
+                data: CupertinoUserInterfaceLevelData.elevated,
+                child: CupertinoSystemColors(
+                  child: Builder(builder: systemColorGetter),
+                  data: CupertinoSystemColors.of(context).resolveColors(context),
+                ),
+              );
+            },
+          ),
+        ),
+      );
+
+      expect(colors.systemBackground.value, CupertinoSystemColors.fallbackValues.systemBackground.elevatedColor.value);
+    });
+  });
+
+  testWidgets('CupertinoDynamicColor used in a CupertinoTheme', (WidgetTester tester) async {
+    CupertinoDynamicColor color;
+    await tester.pumpWidget(
+      CupertinoApp(
+        theme: CupertinoThemeData(
+          brightness: Brightness.dark,
+          primaryColor: dynamicColor,
+        ),
+        home: Builder(
+          builder: (BuildContext context) {
+            color = CupertinoTheme.of(context).primaryColor;
+            return const Placeholder();
+          }
+        ),
+      ),
+    );
+
+    expect(color.value, dynamicColor.darkColor.value);
+
+    // Changing dependencies works.
+    await tester.pumpWidget(
+      CupertinoApp(
+        theme: CupertinoThemeData(
+          brightness: Brightness.light,
+          primaryColor: dynamicColor,
+        ),
+        home: Builder(
+          builder: (BuildContext context) {
+            color = CupertinoTheme.of(context).primaryColor;
+            return const Placeholder();
+          }
+        ),
+      ),
+    );
+
+    expect(color.value, dynamicColor.color.value);
+
+    // Having a dependency below the CupertinoTheme widget works.
+    await tester.pumpWidget(
+      CupertinoApp(
+        theme: CupertinoThemeData(primaryColor: dynamicColor),
+        home: MediaQuery(
+          data: const MediaQueryData(platformBrightness: Brightness.light, highContrast: false),
+          child: CupertinoUserInterfaceLevel(
+            data: CupertinoUserInterfaceLevelData.base,
+            child: Builder(
+              builder: (BuildContext context) {
+                color = CupertinoTheme.of(context).primaryColor;
+                return const Placeholder();
+              }
+            ),
+          ),
+        ),
+      ),
+    );
+
+    expect(color.value, dynamicColor.color.value);
+
+    // Changing dependencies works.
+    await tester.pumpWidget(
+      CupertinoApp(
+        // No brightness is explicitly specified here so it should defer to MediaQuery.
+        theme: CupertinoThemeData(primaryColor: dynamicColor),
+        home: MediaQuery(
+          data: const MediaQueryData(platformBrightness: Brightness.dark, highContrast: true),
+          child: CupertinoUserInterfaceLevel(
+            data: CupertinoUserInterfaceLevelData.elevated,
+            child: Builder(
+              builder: (BuildContext context) {
+                color = CupertinoTheme.of(context).primaryColor;
+                return const Placeholder();
+              }
+            ),
+          ),
+        ),
+      ),
+    );
+
+    expect(color.value, dynamicColor.darkHighContrastElevatedColor.value);
+  });
+
+  group('MaterialApp:', () {
+    Color color;
+    setUp(() { color = null; });
+
+    testWidgets('dynamic color works in cupertino override theme', (WidgetTester tester) async {
+      final CupertinoDynamicColor Function() typedColor = () => color;
+
+      await tester.pumpWidget(
+        MaterialApp(
+          theme: ThemeData(
+            cupertinoOverrideTheme: CupertinoThemeData(
+              brightness: Brightness.dark,
+              primaryColor: dynamicColor,
+            ),
+          ),
+          home: MediaQuery(
+            data: const MediaQueryData(platformBrightness: Brightness.light, highContrast: false),
+            child: CupertinoUserInterfaceLevel(
+              data: CupertinoUserInterfaceLevelData.base,
+              child: Builder(
+                builder: (BuildContext context) {
+                  color = CupertinoTheme.of(context).primaryColor;
+                  return const Placeholder();
+                }
+              ),
+            ),
+          ),
+        ),
+      );
+
+      // Explicit brightness is respected.
+      expect(typedColor().value, dynamicColor.darkColor.value);
+      color = null;
+
+      // Changing dependencies works.
+      await tester.pumpWidget(
+        MaterialApp(
+          theme: ThemeData(
+            cupertinoOverrideTheme: CupertinoThemeData(
+              brightness: Brightness.dark,
+              primaryColor: dynamicColor,
+            ),
+          ),
+          home: MediaQuery(
+            data: const MediaQueryData(platformBrightness: Brightness.dark, highContrast: true),
+            child: CupertinoUserInterfaceLevel(
+              data: CupertinoUserInterfaceLevelData.elevated,
+              child: Builder(
+                builder: (BuildContext context) {
+                  color = CupertinoTheme.of(context).primaryColor;
+                  return const Placeholder();
+                }
+              ),
+            ),
+          ),
+        ),
+      );
+
+      expect(typedColor().value, dynamicColor.darkHighContrastElevatedColor.value);
+    });
+
+    testWidgets('dynamic color does not work in a material theme', (WidgetTester tester) async {
+      await tester.pumpWidget(
+        MaterialApp(
+          // This will create a MaterialBasedCupertinoThemeData with primaryColor set to `dynamicColor`.
+          theme: ThemeData(colorScheme: ColorScheme.dark(primary: dynamicColor)),
+          home: MediaQuery(
+            data: const MediaQueryData(platformBrightness: Brightness.dark, highContrast: true),
+            child: CupertinoUserInterfaceLevel(
+              data: CupertinoUserInterfaceLevelData.elevated,
+              child: Builder(
+                builder: (BuildContext context) {
+                  color = CupertinoTheme.of(context).primaryColor;
+                  return const Placeholder();
+                }
+              ),
+            ),
+          ),
+        ),
+      );
+
+      // The color is not resolved.
+      expect(color, dynamicColor);
+      expect(color, isNot(dynamicColor.darkHighContrastElevatedColor));
+    });
+  });
+
+  group('CupertinoSystemColors', () {
+    final Color dynamicColor0 = CupertinoDynamicColor.withBrightness(
+      color: const Color(0x00000000),
+      darkColor: const Color(0x00000000)
+    );
+    final Color dynamicColor1 = CupertinoDynamicColor.withBrightness(
+      color: const Color(0x00000001),
+      darkColor: const Color(0x00000000)
+    );
+
+    final CupertinoSystemColorsData system0 = CupertinoSystemColorsData(
+      label: dynamicColor0,
+      secondaryLabel: dynamicColor0,
+      tertiaryLabel: dynamicColor0,
+      quaternaryLabel: dynamicColor0,
+      systemFill: dynamicColor0,
+      secondarySystemFill: dynamicColor0,
+      tertiarySystemFill: dynamicColor0,
+      quaternarySystemFill: dynamicColor0,
+      placeholderText: dynamicColor0,
+      systemBackground: dynamicColor0,
+      secondarySystemBackground: dynamicColor0,
+      tertiarySystemBackground: dynamicColor0,
+      systemGroupedBackground: dynamicColor0,
+      secondarySystemGroupedBackground: dynamicColor0,
+      tertiarySystemGroupedBackground: dynamicColor0,
+      separator: dynamicColor0,
+      opaqueSeparator: dynamicColor0,
+      link: dynamicColor0,
+      systemBlue: dynamicColor0,
+      systemGreen: dynamicColor0,
+      systemIndigo: dynamicColor0,
+      systemOrange: dynamicColor0,
+      systemPink: dynamicColor0,
+      systemPurple: dynamicColor0,
+      systemRed: dynamicColor0,
+      systemTeal: dynamicColor0,
+      systemYellow: dynamicColor0,
+      systemGray: dynamicColor0,
+      systemGray2: dynamicColor0,
+      systemGray3: dynamicColor0,
+      systemGray4: dynamicColor0,
+      systemGray5: dynamicColor0,
+      systemGray6: dynamicColor0,
+    );
+
+    test('CupertinoSystemColorsData.== and CupertinoSystemColorsData.copyWith', () {
+      expect(system0, system0);
+      expect(system0, system0.copyWith());
+      expect(system0, system0.copyWith(link: dynamicColor0));
+      final CupertinoSystemColorsData withDifferentLink = system0.copyWith(link: dynamicColor1);
+      expect(withDifferentLink.link, dynamicColor1);
+      expect(system0, isNot(withDifferentLink));
+    });
+
+    test('CupertinoSystemColorsData.hashCode', () {
+      expect(system0.hashCode, system0.hashCode);
+      expect(system0.hashCode, system0.copyWith().hashCode);
+      expect(system0.hashCode, system0.copyWith(link: dynamicColor0).hashCode);
+      expect(system0.hashCode, isNot(system0.copyWith(link: dynamicColor1).hashCode));
+    });
+
+    test('CupertinoSystemColorsData.debugFillProperties', () {
+      final DiagnosticPropertiesBuilder builder = DiagnosticPropertiesBuilder();
+      system0.debugFillProperties(builder);
+
+      expect(
+        builder.properties
+        .where((DiagnosticsNode node) => !node.isFiltered(DiagnosticLevel.info))
+        .map((DiagnosticsNode node) => node.toString())
+        .toList(),
+        <String>[
+          'label: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'secondaryLabel: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'tertiaryLabel: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'quaternaryLabel: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'systemFill: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'secondarySystemFill: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'tertiarySystemFill: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'quaternarySystemFill: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'placeholderText: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'systemBackground: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'secondarySystemBackground: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'tertiarySystemBackground: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'systemGroupedBackground: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'secondarySystemGroupedBackground: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'tertiarySystemGroupedBackground: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'separator: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'opaqueSeparator: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'link: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'systemBlue: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'systemGreen: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'systemIndigo: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'systemOrange: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'systemPink: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'systemPurple: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'systemRed: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'systemTeal: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'systemYellow: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'systemGray: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'systemGray2: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'systemGray3: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'systemGray4: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'systemGray5: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+          'systemGray6: CupertinoDynamicColor(*color = Color(0x00000000)*)',
+        ],
+      );
+    });
+  });
+}

packages/flutter/test/cupertino/slider_test.dart

@@ -24,26 +24,28 @@ void main() {
     final Key sliderKey = UniqueKey();
     double value = 0.0;
 
-    await tester.pumpWidget(Directionality(
+    await tester.pumpWidget(
-      textDirection: TextDirection.ltr,
+      CupertinoApp(
-      child: StatefulBuilder(
+        home: Directionality(
-        builder: (BuildContext context, StateSetter setState) {
+          textDirection: TextDirection.ltr,
-          return Material(
+          child: StatefulBuilder(
-            child: Center(
+            builder: (BuildContext context, StateSetter setState) {
-              child: CupertinoSlider(
+              return Material(
-                key: sliderKey,
+                child: Center(
-                value: value,
+                  child: CupertinoSlider(
-                onChanged: (double newValue) {
+                    key: sliderKey,
-                  setState(() {
+                    value: value,
-                    value = newValue;
+                    onChanged: (double newValue) {
-                  });
+                      setState(() { value = newValue; });
-                },
+                    },
-              ),
+                  ),
-            ),
+                ),
-          );
+              );
-        },
+            },
+          ),
+        ),
       ),
-    ));
+    );
 
     expect(value, equals(0.0));
     await tester.tap(find.byKey(sliderKey));
@@ -58,26 +60,28 @@ void main() {
     final Key sliderKey = UniqueKey();
     double value = 0.0;
 
-    await tester.pumpWidget(Directionality(
+    await tester.pumpWidget(
-      textDirection: TextDirection.rtl,
+      CupertinoApp(
-      child: StatefulBuilder(
+        home: Directionality(
-        builder: (BuildContext context, StateSetter setState) {
+          textDirection: TextDirection.rtl,
-          return Material(
+          child: StatefulBuilder(
-            child: Center(
+            builder: (BuildContext context, StateSetter setState) {
-              child: CupertinoSlider(
+              return Material(
-                key: sliderKey,
+                child: Center(
-                value: value,
+                  child: CupertinoSlider(
-                onChanged: (double newValue) {
+                    key: sliderKey,
-                  setState(() {
+                    value: value,
-                    value = newValue;
+                    onChanged: (double newValue) {
-                  });
+                      setState(() { value = newValue; });
-                },
+                    },
-              ),
+                  ),
-            ),
+                ),
-          );
+              );
-        },
+            },
+          ),
+        ),
       ),
-    ));
+    );
 
     expect(value, equals(0.0));
     await tester.tap(find.byKey(sliderKey));
@@ -93,29 +97,31 @@ void main() {
     double value = 0.0;
     int numberOfTimesOnChangeStartIsCalled = 0;
 
-    await tester.pumpWidget(Directionality(
+    await tester.pumpWidget(
-      textDirection: TextDirection.ltr,
+      CupertinoApp(
-      child: StatefulBuilder(
+        home: Directionality(
-        builder: (BuildContext context, StateSetter setState) {
+          textDirection: TextDirection.ltr,
-          return Material(
+          child: StatefulBuilder(
-            child: Center(
+            builder: (BuildContext context, StateSetter setState) {
-              child: CupertinoSlider(
+              return Material(
-                key: sliderKey,
+                child: Center(
-                value: value,
+                  child: CupertinoSlider(
-                onChanged: (double newValue) {
+                    key: sliderKey,
-                  setState(() {
+                    value: value,
-                    value = newValue;
+                    onChanged: (double newValue) {
-                  });
+                      setState(() { value = newValue; });
-                },
+                    },
-                onChangeStart: (double value) {
+                    onChangeStart: (double value) {
-                  numberOfTimesOnChangeStartIsCalled++;
+                      numberOfTimesOnChangeStartIsCalled++;
-                },
+                    },
-              ),
+                  ),
-            ),
+                ),
-          );
+              );
-        },
+            },
+          ),
+        ),
       ),
-    ));
+    );
 
     await _dragSlider(tester, sliderKey);
 
@@ -132,29 +138,31 @@ void main() {
     double value = 0.0;
     int numberOfTimesOnChangeEndIsCalled = 0;
 
-    await tester.pumpWidget(Directionality(
+    await tester.pumpWidget(
-      textDirection: TextDirection.ltr,
+      CupertinoApp(
-      child: StatefulBuilder(
+        home: Directionality(
-        builder: (BuildContext context, StateSetter setState) {
+          textDirection: TextDirection.ltr,
-          return Material(
+          child: StatefulBuilder(
-            child: Center(
+            builder: (BuildContext context, StateSetter setState) {
-              child: CupertinoSlider(
+              return Material(
-                key: sliderKey,
+                child: Center(
-                value: value,
+                  child: CupertinoSlider(
-                onChanged: (double newValue) {
+                    key: sliderKey,
-                  setState(() {
+                    value: value,
-                    value = newValue;
+                    onChanged: (double newValue) {
-                  });
+                      setState(() { value = newValue; });
-                },
+                    },
-                onChangeEnd: (double value) {
+                    onChangeEnd: (double value) {
-                  numberOfTimesOnChangeEndIsCalled++;
+                      numberOfTimesOnChangeEndIsCalled++;
-                },
+                    },
-              ),
+                  ),
-            ),
+                ),
-          );
+              );
-        },
+            },
+          ),
+        ),
       ),
-    ));
+    );
 
     await _dragSlider(tester, sliderKey);
 
@@ -172,32 +180,34 @@ void main() {
     double startValue;
     double endValue;
 
-    await tester.pumpWidget(Directionality(
+    await tester.pumpWidget(
-      textDirection: TextDirection.ltr,
+      CupertinoApp(
-      child: StatefulBuilder(
+        home: Directionality(
-        builder: (BuildContext context, StateSetter setState) {
+          textDirection: TextDirection.ltr,
-          return Material(
+          child: StatefulBuilder(
-            child: Center(
+            builder: (BuildContext context, StateSetter setState) {
-              child: CupertinoSlider(
+              return Material(
-                key: sliderKey,
+                child: Center(
-                value: value,
+                  child: CupertinoSlider(
-                onChanged: (double newValue) {
+                    key: sliderKey,
-                  setState(() {
+                    value: value,
-                    value = newValue;
+                    onChanged: (double newValue) {
-                  });
+                      setState(() { value = newValue; });
-                },
+                    },
-                onChangeStart: (double value) {
+                    onChangeStart: (double value) {
-                  startValue = value;
+                      startValue = value;
-                },
+                    },
-                onChangeEnd: (double value) {
+                    onChangeEnd: (double value) {
-                  endValue = value;
+                      endValue = value;
-                },
+                    },
-              ),
+                  ),
-            ),
+                ),
-          );
+              );
-        },
+            },
+          ),
+        ),
       ),
-    ));
+    );
 
     expect(value, equals(0.0));
 
@@ -224,36 +234,34 @@ void main() {
     double startValue;
     double endValue;
 
-    await tester.pumpWidget(Directionality(
+    await tester.pumpWidget(
-      textDirection: TextDirection.rtl,
+      CupertinoApp(
-      child: StatefulBuilder(
+        home: Directionality(
-        builder: (BuildContext context, StateSetter setState) {
+          textDirection: TextDirection.rtl,
-          return Material(
+          child: StatefulBuilder(
-            child: Center(
+            builder: (BuildContext context, StateSetter setState) {
-              child: CupertinoSlider(
+              return Material(
-                key: sliderKey,
+                child: Center(
-                value: value,
+                  child: CupertinoSlider(
-                onChanged: (double newValue) {
+                    key: sliderKey,
-                  setState(() {
+                    value: value,
-                    value = newValue;
+                    onChanged: (double newValue) {
-                  });
+                      setState(() { value = newValue; });
-                },
+                    },
-                onChangeStart: (double value) {
+                    onChangeStart: (double value) {
-                  setState(() {
+                      setState(() { startValue = value; });
-                    startValue = value;
+                    },
-                  });
+                    onChangeEnd: (double value) {
-                },
+                      setState(() { endValue = value; });
-                onChangeEnd: (double value) {
+                    },
-                  setState(() {
+                  ),
-                    endValue = value;
+                ),
-                  });
+              );
-                },
+            },
-              ),
+          ),
-            ),
+        ),
-          );
-        },
       ),
-    ));
+    );
 
     expect(value, equals(0.0));
 
@@ -277,13 +285,18 @@ void main() {
   testWidgets('Slider Semantics', (WidgetTester tester) async {
     final SemanticsTester semantics = SemanticsTester(tester);
 
-    await tester.pumpWidget(Directionality(
+    await tester.pumpWidget(
-      textDirection: TextDirection.ltr,
+      MediaQuery(
-      child: CupertinoSlider(
+        data: const MediaQueryData(),
-        value: 0.5,
+        child: Directionality(
-        onChanged: (double v) { },
+          textDirection: TextDirection.ltr,
+          child: CupertinoSlider(
+            value: 0.5,
+            onChanged: (double v) { },
+          ),
+        ),
       ),
-    ));
+    );
 
     expect(semantics, hasSemantics(
       TestSemantics.root(
@@ -296,20 +309,25 @@ void main() {
             textDirection: TextDirection.ltr,
             actions: SemanticsAction.decrease.index | SemanticsAction.increase.index,
           ),
-        ]
+        ],
       ),
       ignoreRect: true,
       ignoreTransform: true,
     ));
 
     // Disable slider
-    await tester.pumpWidget(const Directionality(
+    await tester.pumpWidget(
-      textDirection: TextDirection.ltr,
+      const MediaQuery(
-      child: CupertinoSlider(
+        data: MediaQueryData(),
-        value: 0.5,
+        child: Directionality(
-        onChanged: null,
+          textDirection: TextDirection.ltr,
+          child: CupertinoSlider(
+            value: 0.5,
+            onChanged: null,
+          ),
+        ),
       ),
-    ));
+    );
 
     expect(semantics, hasSemantics(
       TestSemantics.root(),
@@ -323,13 +341,17 @@ void main() {
   testWidgets('Slider Semantics can be updated', (WidgetTester tester) async {
     final SemanticsHandle handle = tester.ensureSemantics();
     double value = 0.5;
-    await tester.pumpWidget(Directionality(
+    await tester.pumpWidget(
-      textDirection: TextDirection.ltr,
+      CupertinoApp(
-      child: CupertinoSlider(
+        home: Directionality(
-        value: value,
+          textDirection: TextDirection.ltr,
-        onChanged: (double v) { },
+          child: CupertinoSlider(
+            value: value,
+            onChanged: (double v) { },
+          ),
+        ),
       ),
-    ));
+    );
 
     expect(tester.getSemantics(find.byType(CupertinoSlider)), matchesSemantics(
       hasIncreaseAction: true,
@@ -341,13 +363,17 @@ void main() {
     ));
 
     value = 0.6;
-    await tester.pumpWidget(Directionality(
+    await tester.pumpWidget(
-      textDirection: TextDirection.ltr,
+      CupertinoApp(
-      child: CupertinoSlider(
+        home: Directionality(
-        value: value,
+          textDirection: TextDirection.ltr,
-        onChanged: (double v) { },
+          child: CupertinoSlider(
+            value: value,
+            onChanged: (double v) { },
+          ),
+        ),
       ),
-    ));
+    );
 
     expect(tester.getSemantics(find.byType(CupertinoSlider)), matchesSemantics(
       hasIncreaseAction: true,
@@ -413,4 +439,108 @@ void main() {
       paints..rrect(color: CupertinoColors.activeGreen),
     );
   });
+
+  testWidgets('Themes can be overridden by dynamic colors', (WidgetTester tester) async {
+    final CupertinoDynamicColor activeColor = CupertinoDynamicColor(
+      color: const Color(0x00000001),
+      darkColor: const Color(0x00000002),
+      elevatedColor: const Color(0x00000003),
+      highContrastColor: const Color(0x00000004),
+      darkElevatedColor: const Color(0x00000005),
+      darkHighContrastColor: const Color(0x00000006),
+      highContrastElevatedColor: const Color(0x00000007),
+      darkHighContrastElevatedColor: const Color(0x00000008),
+    );
+
+    Widget withTraits(Brightness brightness, CupertinoUserInterfaceLevelData level, bool highContrast) {
+      return CupertinoTheme(
+        data: CupertinoThemeData(brightness: brightness),
+        child: CupertinoUserInterfaceLevel(
+          data: level,
+          child: MediaQuery(
+            data: MediaQueryData(highContrast: highContrast),
+            child: Center(
+              child: CupertinoSlider(
+                activeColor: activeColor,
+                onChanged: (double value) { },
+                value: 0.5,
+              ),
+            ),
+          ),
+        ),
+      );
+    }
+
+    await tester.pumpWidget(CupertinoApp(home: withTraits(Brightness.light, CupertinoUserInterfaceLevelData.base, false)));
+    expect(find.byType(CupertinoSlider), paints..rrect(color: activeColor.color));
+
+    await tester.pumpWidget(CupertinoApp(home: withTraits(Brightness.dark, CupertinoUserInterfaceLevelData.base, false)));
+    expect(find.byType(CupertinoSlider), paints..rrect(color: activeColor.darkColor));
+
+    await tester.pumpWidget(CupertinoApp(home: withTraits(Brightness.dark, CupertinoUserInterfaceLevelData.elevated, false)));
+    expect(find.byType(CupertinoSlider), paints..rrect(color: activeColor.darkElevatedColor));
+
+    await tester.pumpWidget(CupertinoApp(home: withTraits(Brightness.dark, CupertinoUserInterfaceLevelData.base, true)));
+    expect(find.byType(CupertinoSlider), paints..rrect(color: activeColor.darkHighContrastColor));
+
+    await tester.pumpWidget(CupertinoApp(home: withTraits(Brightness.dark, CupertinoUserInterfaceLevelData.elevated, true)));
+    expect(find.byType(CupertinoSlider), paints..rrect(color: activeColor.darkHighContrastElevatedColor));
+
+    await tester.pumpWidget(CupertinoApp(home: withTraits(Brightness.light, CupertinoUserInterfaceLevelData.base, true)));
+    expect(find.byType(CupertinoSlider), paints..rrect(color: activeColor.highContrastColor));
+
+    await tester.pumpWidget(CupertinoApp(home: withTraits(Brightness.light, CupertinoUserInterfaceLevelData.elevated, false)));
+    expect(find.byType(CupertinoSlider), paints..rrect(color: activeColor.elevatedColor));
+
+    await tester.pumpWidget(CupertinoApp(home: withTraits(Brightness.light, CupertinoUserInterfaceLevelData.elevated, true)));
+    expect(find.byType(CupertinoSlider), paints..rrect(color: activeColor.highContrastElevatedColor));
+  });
+
+  testWidgets('track color is dynamic', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      CupertinoApp(
+        theme: const CupertinoThemeData(brightness: Brightness.light),
+        home: Center(
+          child: CupertinoSlider(
+            activeColor: CupertinoColors.activeGreen,
+            onChanged: (double value) { },
+            value: 0,
+          ),
+        ),
+      ),
+    );
+
+    expect(
+      find.byType(CupertinoSlider),
+      paints..rrect(color: CupertinoSystemColors.fallbackValues.systemFill.color),
+    );
+
+    expect(
+      find.byType(CupertinoSlider),
+      isNot(paints..rrect(color: CupertinoSystemColors.fallbackValues.systemFill.darkColor)),
+    );
+
+    await tester.pumpWidget(
+      CupertinoApp(
+        theme: const CupertinoThemeData(brightness: Brightness.dark),
+        home: Center(
+          child: CupertinoSlider(
+            activeColor: CupertinoColors.activeGreen,
+            onChanged: (double value) { },
+            value: 0,
+          ),
+        ),
+      ),
+    );
+
+    expect(
+      find.byType(CupertinoSlider),
+      paints..rrect(color: CupertinoSystemColors.fallbackValues.systemFill.darkColor),
+    );
+
+    expect(
+      find.byType(CupertinoSlider),
+      isNot(paints..rrect(color: CupertinoSystemColors.fallbackValues.systemFill.color)),
+    );
+  });
 }