Package io.flutter.embedding.android

Class KeyboardManager

java.lang.Object

io.flutter.embedding.android.KeyboardManager

All Implemented Interfaces:

InputConnectionAdaptor.KeyboardDelegate

public class KeyboardManager
extends Object
implements InputConnectionAdaptor.KeyboardDelegate

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 new @{link 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.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	KeyboardManager.CharacterCombiner	Applies the given Unicode character from KeyEvent.getUnicodeChar() to a previously entered Unicode combining character and returns the combination of these characters if a combination exists.
static interface	KeyboardManager.Responder	The interface for responding to a KeyEvent asynchronously.
static interface	KeyboardManager.ViewDelegate	A set of interfaces that the KeyboardManager needs to interact with other components and the platform, and is typically implements by FlutterView.

Field Summary

Fields

Modifier and Type	Field	Description
protected KeyboardManager.Responder[]	responders

Constructor Summary

Constructors

Constructor	Description
KeyboardManager(KeyboardManager.ViewDelegate viewDelegate)	Construct a KeyboardManager.

Method Summary

Modifier and Type	Method	Description
void	destroy()
boolean	handleEvent(KeyEvent keyEvent)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

responders

protected final KeyboardManager.Responder[] responders

Constructor Detail

KeyboardManager

public KeyboardManager(@NonNull
                       KeyboardManager.ViewDelegate viewDelegate)

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.

Method Detail

handleEvent

public boolean handleEvent(@NonNull
                           KeyEvent keyEvent)

Specified by:

handleEvent in interface InputConnectionAdaptor.KeyboardDelegate

destroy

public void destroy()