io.flutter.embedding.android.KeyboardManager Class Reference

Inheritance diagram for io.flutter.embedding.android.KeyboardManager:

Classes
class	CharacterCombiner
interface	Responder
interface	ViewDelegate

Public Member Functions
	KeyboardManager (@NonNull ViewDelegate viewDelegate)
boolean	handleEvent (@NonNull KeyEvent keyEvent)
void	destroy ()
Map< Long, Long >	getKeyboardState ()

Protected Attributes
final Responder[]	responders

Detailed Description

Processes keyboard events and cooperate with TextInputPlugin.

Flutter uses asynchronous event handling to avoid blocking the UI thread, but Android requires that events are handled synchronously. So when the Android system sends newlink KeyEvent} to Flutter, Flutter responds synchronously that the key has been handled so that it won't propagate to other components. It then uses "delayed event synthesis", where it sends the event to the framework, and if the framework responds that it has not handled the event, then this class synthesizes a new event to send to Android, without handling it this time.

Flutter processes an Android KeyEvent with several components, each can choose whether to handled the event, and only unhandled events can move to the next section.

• Keyboard: Dispatch to the KeyboardManager.Responders simultaneously. After all responders have responded (asynchronously), the event is considered handled if any responders decide to handle.
• Text input: Events are sent to TextInputPlugin, processed synchronously with a result of whether it is handled.
• "Redispatch": If there's no currently focused text field in TextInputPlugin, or the text field does not handle the KeyEvent either, the KeyEvent will be sent back to the top of the activity's view hierachy, allowing it to be "redispatched". The KeyboardManager will remember this event and skip the identical event at the next encounter.

Definition at line 45 of file KeyboardManager.java.

Constructor & Destructor Documentation

KeyboardManager()

io.flutter.embedding.android.KeyboardManager.KeyboardManager ( @NonNull ViewDelegate  viewDelegate )

inline

Construct a KeyboardManager.

Parameters

viewDelegate

provides a set of interfaces that the keyboard manager needs to interact with other components and the platform, and is typically implements by FlutterView.

Definition at line 118 of file KeyboardManager.java.

                                                             {
    this.viewDelegate = viewDelegate;
    this.responders =
        new Responder[] {
          new KeyEmbedderResponder(viewDelegate.getBinaryMessenger()),
          new KeyChannelResponder(new KeyEventChannel(viewDelegate.getBinaryMessenger())),
        };
    final KeyboardChannel keyboardChannel = new KeyboardChannel(viewDelegate.getBinaryMessenger());
    keyboardChannel.setKeyboardMethodHandler(this);
  }

Member Function Documentation

destroy()

void io.flutter.embedding.android.KeyboardManager.destroy ( )

inline

Definition at line 238 of file KeyboardManager.java.

                        {
    final int remainingRedispatchCount = redispatchedEvents.size();
    if (remainingRedispatchCount > 0) {
      Log.w(
          TAG,
          "A KeyboardManager was destroyed with "
              + String.valueOf(remainingRedispatchCount)
              + " unhandled redispatch event(s).");
    }
  }

getKeyboardState()

Map< Long, Long > io.flutter.embedding.android.KeyboardManager.getKeyboardState ( )

inline

Returns an unmodifiable view of the pressed state.

Returns

A map whose keys are physical keyboard key IDs and values are the corresponding logical keyboard key IDs.

Definition at line 267 of file KeyboardManager.java.

                                            {
    KeyEmbedderResponder embedderResponder = (KeyEmbedderResponder) responders[0];
    return embedderResponder.getPressedState();
  }

handleEvent()

boolean io.flutter.embedding.android.KeyboardManager.handleEvent ( @NonNull KeyEvent  keyEvent )

inline

Definition at line 220 of file KeyboardManager.java.

                                                         {
    final boolean isRedispatchedEvent = redispatchedEvents.remove(keyEvent);
    if (isRedispatchedEvent) {
      return false;
    }
 
    if (responders.length > 0) {
      final PerEventCallbackBuilder callbackBuilder = new PerEventCallbackBuilder(keyEvent);
      for (final Responder primaryResponder : responders) {
        primaryResponder.handleEvent(keyEvent, callbackBuilder.buildCallback());
      }
    } else {
      onUnhandled(keyEvent);
    }
 
    return true;
  }

Member Data Documentation

responders

final Responder [] io.flutter.embedding.android.KeyboardManager.responders

protected

Definition at line 215 of file KeyboardManager.java.

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The documentation for this class was generated from the following file:

• shell/platform/android/io/flutter/embedding/android/KeyboardManager.java