FlutterKeyboardManager Class Reference

#include <FlutterKeyboardManager.h>

Inheritance diagram for FlutterKeyboardManager:

Instance Methods
(void)	- addPrimaryResponder:
(void)	- addSecondaryResponder:
(void)	- handlePress:nextAction:
(nonnull instancetype)	- initWithDelegate:
(void)	- handleEvent:withContext:
(BOOL)	- isDispatchingKeyEvent:
(void)	- syncModifiersIfNeeded:timestamp:
(nonnull NSDictionary *)	- getPressedState
(nonnull instancetype)	- initWithDelegate:keyboardLayout:

Detailed Description

A hub that manages how key events are dispatched to various Flutter key responders, and propagates it to the superclass if the Flutter key responders do not handle it.

This class manages one or more primary responders, as well as zero or more secondary responders.

An event that is received by |handlePresses| is first dispatched to all primary responders. Each primary responder responds asynchronously with a boolean, indicating whether it handles the event.

An event that is not handled by any primary responders is then passed to to the first secondary responder (in the chronological order of addition), which responds synchronously with a boolean, indicating whether it handles the event. If not, the event is passed to the next secondary responder, and so on.

The event is then handed back to the |completeCallback| from the original call to |handlePresses| so that it can respond synchronously to the OS if the event was not handled by the responders. The |completeCallback| is called on the platform thread because the platform thread is blocked by a nested event loop while the response from the framework is being collected, and it needs to be called on the platform thread to unblock the thread by exiting the nested event loop.

Preventing primary responders from receiving events is not supported, because in reality this class only supports two hardcoded responders (FlutterChannelKeyResponder and FlutterEmbedderKeyResponder), where the only purpose of supporting two is to maintain the legacy channel API during the deprecation window, after which the channel responder should be removed, and only one primary responder will exist.

A hub that manages how key events are dispatched to various Flutter key responders, and whether the event is propagated to the next NSResponder. Cooperates with |TextInputPlugin| to handle text

A keyboard event goes through a few sections, each can choose to handled the event, and only unhandled events can move to the next section:

• Pre-filtering: Events during IME are sent to the system immediately.
• Keyboard: Dispatch to the embedder responder and the channel responder simultaneously. After both responders have responded (asynchronously), the event is considered handled if either responder handles.
• Text input: Events are sent to |TextInputPlugin| and are handled synchronously.
• Next responder: Events are sent to the next responder as specified by |viewDelegate|.

Definition at line 53 of file FlutterKeyboardManager.h.

Method Documentation

addPrimaryResponder:

- (void) addPrimaryResponder:

(nonnull id<FlutterKeyPrimaryResponder>)

responder

Add a primary responder, which asynchronously decides whether to handle an event.

Definition at line 26 of file FlutterKeyboardManager.mm.

                           :(nonnull id<FlutterKeyPrimaryResponder>)responder {
  [_primaryResponders addObject:responder];
}

References self.

addSecondaryResponder:

- (void) addSecondaryResponder:

(nonnull id<FlutterKeySecondaryResponder>)

responder

Add a secondary responder, which synchronously decides whether to handle an event in order if no earlier responders handle.

Definition at line 26 of file FlutterKeyboardManager.mm.

                             :(nonnull id<FlutterKeySecondaryResponder>)responder {
  [_secondaryResponders addObject:responder];
}

getPressedState

- (nonnull NSDictionary *) getPressedState

Returns the keyboard pressed state.

Returns the keyboard pressed state. The dictionary contains one entry per pressed keys, mapping from the logical key to the physical key.

Definition at line 92 of file FlutterKeyboardManager.mm.

                                         {
  // The embedder responder is the first element in _primaryResponders.
  FlutterEmbedderKeyResponder* embedderResponder =
      (FlutterEmbedderKeyResponder*)_primaryResponders[0];
  return [embedderResponder getPressedState];
}

handleEvent:withContext:

- (void) handleEvent:		(nonnull NSEvent*)	event
withContext:		(nonnull id<FlutterKeyboardManagerEventContext>)	eventContext

Processes a key event.

Unhandled events will be dispatched to the text input system, and possibly the next responder afterwards.

Definition at line 92 of file FlutterKeyboardManager.mm.

                   :(nonnull NSEvent*)event
        withContext:(nonnull id<FlutterKeyboardManagerEventContext>)context {
  // The `handleEvent` does not process the event immediately, but instead put
  // events into a queue. Events are processed one by one by `processNextEvent`.
 
  // Be sure to add a handling method in propagateKeyEvent when allowing more
  // event types here.
  if (event.type != NSEventTypeKeyDown && event.type != NSEventTypeKeyUp &&
      event.type != NSEventTypeFlagsChanged) {
    return;
  }
 
  [_pendingEvents addObject:[[FlutterEventWithContext alloc] initWithEvent:event context:context]];
  [self processNextEvent];
}

handlePress:nextAction:

- (void) handlePress:		(nonnull FlutterUIPressProxy*)	press
nextAction:		(ios(13.4))	API_AVAILABLE

Dispatches a key press event to all responders, gathering their responses, and then calls the |nextAction| if the event was not handled.

Definition at line 26 of file FlutterKeyboardManager.mm.

                   :(nonnull FlutterUIPressProxy*)press
         nextAction:(nonnull void (^)())next API_AVAILABLE(ios(13.4)) {
  if (@available(iOS 13.4, *)) {
    // no-op
  } else {
    return;
  }
 
  bool __block wasHandled = false;
  KeyEventCompleteCallback completeCallback = ^void(bool handled, FlutterUIPressProxy* press) {
    wasHandled = handled;
    CFRunLoopStop(CFRunLoopGetCurrent());
  };
  switch (press.phase) {
    case UIPressPhaseBegan:
    case UIPressPhaseEnded: {
      // Having no primary responders requires extra logic, but Flutter hard-codes
      // all primary responders, so this is a situation that Flutter will never
      // encounter.
      NSAssert([_primaryResponders count] >= 0, @"At least one primary responder must be added.");
 
      __block __weak __typeof(self) weakSelf = self;
      __block NSUInteger unreplied = [self.primaryResponders count];
      __block BOOL anyHandled = false;
      FlutterAsyncKeyCallback replyCallback = ^(BOOL handled) {
        unreplied--;
        NSAssert(unreplied >= 0, @"More primary responders replied than expected.");
        anyHandled = anyHandled || handled;
        if (unreplied == 0) {
          if (!anyHandled && weakSelf) {
            [weakSelf dispatchToSecondaryResponders:press complete:completeCallback];
          } else {
            completeCallback(true, press);
          }
        }
      };
      for (id<FlutterKeyPrimaryResponder> responder in _primaryResponders) {
        [responder handlePress:press callback:replyCallback];
      }
      // Create a nested run loop while we wait for a response from the
      // framework. Once the completeCallback is called, this run loop will exit
      // and the main one will resume. The completeCallback MUST be called, or
      // the app will get stuck in this run loop indefinitely.
      //
      // We need to run in this mode so that UIKit doesn't give us new
      // events until we are done processing this one.
      CFRunLoopRunInMode(fml::MessageLoopDarwin::kMessageLoopCFRunLoopMode, kDistantFuture, NO);
      break;
    }
    case UIPressPhaseChanged:
    case UIPressPhaseCancelled:
    case UIPressPhaseStationary:
      break;
  }
  if (!wasHandled) {
    next();
  }
}

initWithDelegate:

- (nonnull instancetype) initWithDelegate:

(nonnull id<FlutterKeyboardManagerDelegate>)

delegate

Initial value:

{
  FlutterKeyboardLayout* _keyboardLayout

Create a keyboard manager.

The |viewDelegate| is a weak reference, typically implemented by |FlutterViewController|.

Definition at line 92 of file FlutterKeyboardManager.mm.

                                        :(nonnull id<FlutterKeyboardManagerDelegate>)delegate {
  return [self initWithDelegate:delegate keyboardLayout:[[FlutterKeyboardLayout alloc] init]];
}

initWithDelegate:keyboardLayout:

- (nonnull instancetype) initWithDelegate:		(nonnull id< FlutterKeyboardManagerDelegate >)	delegate
keyboardLayout:		(nonnull FlutterKeyboardLayout *)	keyboardLayout

Provided by category FlutterKeyboardManager(Testing).

isDispatchingKeyEvent:

- (BOOL) isDispatchingKeyEvent:

(nonnull NSEvent *)

event

Returns yes if is event currently being redispatched.

In some instances (i.e. emoji shortcut) the event may be redelivered by cocoa as key equivalent to FlutterTextInput, in which case it shouldn't be processed again.

syncModifiersIfNeeded:timestamp:

- (void) syncModifiersIfNeeded:		(NSEventModifierFlags)	modifierFlags
timestamp:		(NSTimeInterval)	timestamp

Synthesize modifier keys events.

If needed, synthesize modifier keys up and down events by comparing their current pressing states with the given modifier flags.

Definition at line 92 of file FlutterKeyboardManager.mm.

                             :(NSEventModifierFlags)modifierFlags
                    timestamp:(NSTimeInterval)timestamp {
  for (id<FlutterKeyPrimaryResponder> responder in _primaryResponders) {
    [responder syncModifiersIfNeeded:modifierFlags timestamp:timestamp];
  }
}

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

• shell/platform/darwin/ios/framework/Source/FlutterKeyboardManager.h
• shell/platform/darwin/macos/framework/Source/FlutterKeyboardManager.h
• shell/platform/darwin/ios/framework/Source/FlutterKeyboardManager.mm
• shell/platform/darwin/macos/framework/Source/FlutterKeyboardManager.mm