Access on/off labels accessibility setting for switches on iOS (flutter/engine#30764)

engine/src/flutter/lib/ui/window.dart

@@ -771,6 +771,7 @@ class AccessibilityFeatures {
   static const int _kBoldTextIndex = 1 << 3;
   static const int _kReduceMotionIndex = 1 << 4;
   static const int _kHighContrastIndex = 1 << 5;
+  static const int _kOnOffSwitchLabelsIndex = 1 << 6;
 
   // A bitfield which represents each enabled feature.
   final int _index;
@@ -803,6 +804,11 @@ class AccessibilityFeatures {
   /// Only supported on iOS.
   bool get highContrast => _kHighContrastIndex & _index != 0;
 
+  /// The platform is requesting to show on/off labels inside switches.
+  ///
+  /// Only supported on iOS.
+  bool get onOffSwitchLabels => _kOnOffSwitchLabelsIndex & _index != 0;
+
   @override
   String toString() {
     final List<String> features = <String>[];
@@ -818,6 +824,8 @@ class AccessibilityFeatures {
       features.add('reduceMotion');
     if (highContrast)
       features.add('highContrast');
+    if (onOffSwitchLabels)
+      features.add('onOffSwitchLabels');
     return 'AccessibilityFeatures$features';
   }
 

engine/src/flutter/lib/ui/window/platform_configuration.h

@@ -35,6 +35,7 @@ enum class AccessibilityFeatureFlag : int32_t {
   kBoldText = 1 << 3,
   kReduceMotion = 1 << 4,
   kHighContrast = 1 << 5,
+  kOnOffSwitchLabels = 1 << 6,
 };
 
 //--------------------------------------------------------------------------

engine/src/flutter/lib/web_ui/lib/window.dart

@@ -148,6 +148,7 @@ class AccessibilityFeatures {
   static const int _kBoldTextIndex = 1 << 3;
   static const int _kReduceMotionIndex = 1 << 4;
   static const int _kHighContrastIndex = 1 << 5;
+  static const int _kOnOffSwitchLabelsIndex = 1 << 6;
 
   // A bitfield which represents each enabled feature.
   final int _index;
@@ -158,6 +159,7 @@ class AccessibilityFeatures {
   bool get boldText => _kBoldTextIndex & _index != 0;
   bool get reduceMotion => _kReduceMotionIndex & _index != 0;
   bool get highContrast => _kHighContrastIndex & _index != 0;
+  bool get onOffSwitchLabels => _kOnOffSwitchLabelsIndex & _index != 0;
 
   @override
   String toString() {
@@ -180,6 +182,9 @@ class AccessibilityFeatures {
     if (highContrast) {
       features.add('highContrast');
     }
+    if (onOffSwitchLabels) {
+      features.add('onOffSwitchLabels');
+    }
     return 'AccessibilityFeatures$features';
   }
 

engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterViewController.mm

@@ -331,6 +331,13 @@ typedef enum UIAccessibilityContrast : NSInteger {
                  name:UIAccessibilityDarkerSystemColorsStatusDidChangeNotification
                object:nil];
 
+  if (@available(iOS 13.0, *)) {
+    [center addObserver:self
+               selector:@selector(onAccessibilityStatusChanged:)
+                   name:UIAccessibilityOnOffSwitchLabelsDidChangeNotification
+                 object:nil];
+  }
+
   [center addObserver:self
              selector:@selector(onUserSettingsChanged:)
                  name:UIContentSizeCategoryDidChangeNotification
@@ -1417,19 +1424,7 @@ static flutter::PointerData::DeviceKind DeviceKindFromTouchType(UITouch* touch)
     return;
   }
   auto platformView = [_engine.get() platformView];
-  int32_t flags = 0;
-  if (UIAccessibilityIsInvertColorsEnabled()) {
-    flags |= static_cast<int32_t>(flutter::AccessibilityFeatureFlag::kInvertColors);
-  }
-  if (UIAccessibilityIsReduceMotionEnabled()) {
-    flags |= static_cast<int32_t>(flutter::AccessibilityFeatureFlag::kReduceMotion);
-  }
-  if (UIAccessibilityIsBoldTextEnabled()) {
-    flags |= static_cast<int32_t>(flutter::AccessibilityFeatureFlag::kBoldText);
-  }
-  if (UIAccessibilityDarkerSystemColorsEnabled()) {
-    flags |= static_cast<int32_t>(flutter::AccessibilityFeatureFlag::kHighContrast);
-  }
+  int32_t flags = [self accessibilityFlags];
 #if TARGET_OS_SIMULATOR
   // There doesn't appear to be any way to determine whether the accessibility
   // inspector is enabled on the simulator. We conservatively always turn on the
@@ -1447,6 +1442,35 @@ static flutter::PointerData::DeviceKind DeviceKindFromTouchType(UITouch* touch)
 #endif
 }
 
+- (int32_t)accessibilityFlags {
+  int32_t flags = 0;
+  if (UIAccessibilityIsInvertColorsEnabled()) {
+    flags |= static_cast<int32_t>(flutter::AccessibilityFeatureFlag::kInvertColors);
+  }
+  if (UIAccessibilityIsReduceMotionEnabled()) {
+    flags |= static_cast<int32_t>(flutter::AccessibilityFeatureFlag::kReduceMotion);
+  }
+  if (UIAccessibilityIsBoldTextEnabled()) {
+    flags |= static_cast<int32_t>(flutter::AccessibilityFeatureFlag::kBoldText);
+  }
+  if (UIAccessibilityDarkerSystemColorsEnabled()) {
+    flags |= static_cast<int32_t>(flutter::AccessibilityFeatureFlag::kHighContrast);
+  }
+  if ([FlutterViewController accessibilityIsOnOffSwitchLabelsEnabled]) {
+    flags |= static_cast<int32_t>(flutter::AccessibilityFeatureFlag::kOnOffSwitchLabels);
+  }
+
+  return flags;
+}
+
++ (BOOL)accessibilityIsOnOffSwitchLabelsEnabled {
+  if (@available(iOS 13, *)) {
+    return UIAccessibilityIsOnOffSwitchLabelsEnabled();
+  } else {
+    return NO;
+  }
+}
+
 #pragma mark - Set user settings
 
 - (void)traitCollectionDidChange:(UITraitCollection*)previousTraitCollection {

engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterViewControllerTest.mm

@@ -6,6 +6,7 @@
 #import <XCTest/XCTest.h>
 
 #include "flutter/fml/platform/darwin/message_loop_darwin.h"
+#import "flutter/lib/ui/window/platform_configuration.h"
 #import "flutter/lib/ui/window/viewport_metrics.h"
 #import "flutter/shell/platform/darwin/common/framework/Headers/FlutterBinaryMessenger.h"
 #import "flutter/shell/platform/darwin/common/framework/Headers/FlutterMacros.h"
@@ -25,10 +26,6 @@ FLUTTER_ASSERT_ARC
             userData:(nullable void*)userData;
 @end
 
-namespace flutter {
-class PointerDataPacket {};
-}
-
 /// Sometimes we have to use a custom mock to avoid retain cycles in OCMock.
 /// Used for testing low memory notification.
 @interface FlutterEnginePartialMock : FlutterEngine
@@ -617,6 +614,46 @@ typedef enum UIAccessibilityContrast : NSInteger {
   [mockTraitCollection stopMocking];
 }
 
+- (void)testItReportsAccessibilityOnOffSwitchLabelsFlagNotSet {
+  if (@available(iOS 13, *)) {
+    // noop
+  } else {
+    return;
+  }
+
+  // Setup test.
+  FlutterViewController* viewController =
+      [[FlutterViewController alloc] initWithEngine:self.mockEngine nibName:nil bundle:nil];
+  id partialMockViewController = OCMPartialMock(viewController);
+  OCMStub([partialMockViewController accessibilityIsOnOffSwitchLabelsEnabled]).andReturn(NO);
+
+  // Exercise behavior under test.
+  int32_t flags = [partialMockViewController accessibilityFlags];
+
+  // Verify behavior.
+  XCTAssert((flags & (int32_t)flutter::AccessibilityFeatureFlag::kOnOffSwitchLabels) == 0);
+}
+
+- (void)testItReportsAccessibilityOnOffSwitchLabelsFlagSet {
+  if (@available(iOS 13, *)) {
+    // noop
+  } else {
+    return;
+  }
+
+  // Setup test.
+  FlutterViewController* viewController =
+      [[FlutterViewController alloc] initWithEngine:self.mockEngine nibName:nil bundle:nil];
+  id partialMockViewController = OCMPartialMock(viewController);
+  OCMStub([partialMockViewController accessibilityIsOnOffSwitchLabelsEnabled]).andReturn(YES);
+
+  // Exercise behavior under test.
+  int32_t flags = [partialMockViewController accessibilityFlags];
+
+  // Verify behavior.
+  XCTAssert((flags & (int32_t)flutter::AccessibilityFeatureFlag::kOnOffSwitchLabels) != 0);
+}
+
 - (void)testPerformOrientationUpdateForcesOrientationChange {
   [self orientationTestWithOrientationUpdate:UIInterfaceOrientationMaskPortrait
                           currentOrientation:UIInterfaceOrientationLandscapeLeft
@@ -1052,7 +1089,7 @@ typedef enum UIAccessibilityContrast : NSInteger {
   [vc scrollEvent:mockPanGestureRecognizer];
 
   [[[self.mockEngine verify] ignoringNonObjectArgs]
-      dispatchPointerDataPacket:std::make_unique<flutter::PointerDataPacket>()];
+      dispatchPointerDataPacket:std::make_unique<flutter::PointerDataPacket>(0)];
 }
 
 @end

engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterViewController_Internal.h

@@ -29,6 +29,7 @@ extern NSNotificationName const FlutterViewControllerShowHomeIndicator;
 
 @interface FlutterViewController () <FlutterViewResponder>
 
+@property(class, nonatomic, readonly) BOOL accessibilityIsOnOffSwitchLabelsEnabled;
 @property(nonatomic, readonly) BOOL isPresentingViewController;
 @property(nonatomic, readonly) BOOL isVoiceOverRunning;
 @property(nonatomic, retain) FlutterKeyboardManager* keyboardManager;
@@ -45,6 +46,7 @@ extern NSNotificationName const FlutterViewControllerShowHomeIndicator;
               nextAction:(void (^)())nextAction API_AVAILABLE(ios(13.4));
 - (void)addInternalPlugins;
 - (void)deregisterNotifications;
+- (int32_t)accessibilityFlags;
 @end
 
 #endif  // FLUTTER_SHELL_PLATFORM_DARWIN_IOS_FRAMEWORK_SOURCE_FLUTTERVIEWCONTROLLER_INTERNAL_H_