Class AccessibilityChannel


public class AccessibilityChannel extends Object
System channel that sends accessibility requests and events from Flutter to Android.

See AccessibilityChannel.AccessibilityMessageHandler, which lists all accessibility requests and events that might be sent from Flutter to the Android platform.

  • Field Details

  • Constructor Details

    • AccessibilityChannel

      public AccessibilityChannel(@NonNull DartExecutor dartExecutor, @NonNull FlutterJNI flutterJNI)
      Constructs an AccessibilityChannel that connects Android to the Dart code running in dartExecutor.

      The given dartExecutor is permitted to be idle or executing code.

      See DartExecutor.

    • AccessibilityChannel

      public AccessibilityChannel(@NonNull BasicMessageChannel<Object> channel, @NonNull FlutterJNI flutterJNI)
  • Method Details

    • onAndroidAccessibilityEnabled

      public void onAndroidAccessibilityEnabled()
      Informs Flutter that the Android OS currently has accessibility enabled.

      To accommodate enabled accessibility, this method instructs Flutter to activate its semantics tree, which forms the basis of Flutter's accessibility support.

    • onAndroidAccessibilityDisabled

      public void onAndroidAccessibilityDisabled()
      Informs Flutter that the Android OS currently has accessibility disabled.

      Given that accessibility is not required at this time, this method instructs Flutter to deactivate its semantics tree.

    • setAccessibilityFeatures

      public void setAccessibilityFeatures(int accessibilityFeatureFlags)
      Instructs Flutter to activate/deactivate accessibility features corresponding to the flags provided by accessibilityFeatureFlags.
    • dispatchSemanticsAction

      public void dispatchSemanticsAction(int virtualViewId, @NonNull AccessibilityBridge.Action action)
      Instructs Flutter to perform the given action on the SemanticsNode referenced by the given virtualViewId.

      One might wonder why Flutter would need to be instructed that the user wants to perform an action. When the user is touching the screen in accessibility mode, Android takes over the touch input, categorizing input as one of a many accessibility gestures. Therefore, Flutter does not have an opportunity to react to said touch input. Instead, Flutter must be notified by Android of the desired action. Additionally, some accessibility systems use other input methods, such as speech, to take virtual actions. Android interprets those requests and then instructs the app to take the appropriate action.

    • dispatchSemanticsAction

      public void dispatchSemanticsAction(int virtualViewId, @NonNull AccessibilityBridge.Action action, @Nullable Object args)
      Instructs Flutter to perform the given action on the SemanticsNode referenced by the given virtualViewId, passing the given args.
    • setAccessibilityMessageHandler

      public void setAccessibilityMessageHandler(@Nullable AccessibilityChannel.AccessibilityMessageHandler handler)
      Sets the AccessibilityChannel.AccessibilityMessageHandler which receives all events and requests that are parsed from the underlying accessibility channel.