fix(mac): properly manage Input Method lifecycle

mac/Keyman4MacIM/Keyman4MacIM/KMInputController.h

@@ -14,5 +14,6 @@
 
 - (void)menuAction:(id)sender;
 - (void)handleBackspace:(NSEvent *)event;
-
+- (void)changeClients:(NSString *)clientAppId;
+- (void)deactivateClient;
 @end

mac/Keyman4MacIM/Keyman4MacIM/KMInputController.m

@@ -25,22 +25,13 @@ - (KMInputMethodAppDelegate *)appDelegate {
 
 - (id)initWithServer:(IMKServer *)server delegate:(id)delegate client:(id)inputClient
 {
-  os_log_debug([KMLogs lifecycleLog], "initWithServer, active app: '%{public}@'", [KMInputMethodLifecycle getRunningApplicationId]);
+  os_log_debug([KMLogs lifecycleLog], "+++KMInputController initWithServer, active app: '%{public}@'", [KMInputMethodLifecycle getRunningApplicationId]);
 
   self = [super initWithServer:server delegate:delegate client:inputClient];
   if (self) {
-    self.appDelegate.inputController = self;
+    os_log_debug([KMLogs lifecycleLog], " +++initWithServer, self: %p", self);
   }
 
-  /**
-   * Register to receive the Deactivated and ChangedClient notification generated from KMInputMethodLifecycle so
-   * that the eventHandler can be changed. There is no need to receive the Activated notification because
-   * the InputController does it all it needs to when it receives the ChangedClient.
-   */
-
-  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(inputMethodDeactivated:) name:kInputMethodDeactivatedNotification object:nil];
-  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(inputMethodChangedClient:) name:kInputMethodClientChangeNotification object:nil];
-
   return self;
 }
 
@@ -67,35 +58,74 @@ - (void)handleBackspace:(NSEvent *)event {
 }
 
 /**
- * The Keyman input method is deactivating because the user chose a different input method: notification from KMInputMethodLifecycle
+ * Called by the app delegate when KMInputMethodLifecycle determines the user has switched clients
  */
-- (void)inputMethodDeactivated:(NSNotification *)notification {
-  os_log_debug([KMLogs lifecycleLog], "***KMInputController inputMethodDeactivated, deactivating eventHandler");
-  if (_eventHandler != nil) {
-    [_eventHandler deactivate];
-  }
+- (void)changeClients:(NSString *)clientAppId {
+  os_log_debug([KMLogs lifecycleLog], "***KMInputController changeClients, deactivate old eventHandler and activate new one");
+
+  [self deactivateEventHandler];
+  [self activateEventHandler:clientAppId];
 }
 
 /**
- * The user has switched to a different text input client: notification from KMInputMethodLifecycle
+ * Called by the app delegate when KMInputMethodLifecycle determines the user has deactivated Keyman
  */
-- (void)inputMethodChangedClient:(NSNotification *)notification {
-  os_log_debug([KMLogs lifecycleLog], "***KMInputController inputMethodChangedClient, deactivating old eventHandler and activating new one");
+- (void)deactivateClient {
+  os_log_debug([KMLogs lifecycleLog], "***KMInputController deactivateClient, deactivate old eventHandler");
+
+  [self deactivateEventHandler];
+}
+
+- (void)deactivateEventHandler {
   if (_eventHandler != nil) {
+    os_log_debug([KMLogs lifecycleLog], " * KMInputController deactivate old eventHandler");
     [_eventHandler deactivate];
   }
-  _eventHandler = [[KMInputMethodEventHandler alloc] initWithClient:[KMInputMethodLifecycle getRunningApplicationId] client:self.client];
+}
 
+- (void)activateEventHandler:(NSString *)clientAppId {
+  os_log_debug([KMLogs lifecycleLog], " * KMInputController activate new eventHandler");
+  _eventHandler = [[KMInputMethodEventHandler alloc] initWithClient:clientAppId client:self.client];
 }
 
+/**
+ * Called by the OS to activate the input method, but some calls are not useful and are followed milliseconds later
+ * by a deactivateServer. These short-lived activations may be generated by clicking and releasing menu items without changing applications.
+ * Rather than treat every message received as a true activation, we send a message to KMInputMethodLifeCycle to evaluate.
+ */
 - (void)activateServer:(id)sender {
+  os_log_info([KMLogs lifecycleLog], " +++KMInputController, activateServer, self=%p", self);
   [sender overrideKeyboardWithKeyboardNamed:@"com.apple.keylayout.US"];
+
+  /**
+   * When this KMInputController becomes the active server for the input method, then immediately update the AppDelegate.
+   * The duration that this controller is the active server may be extremely short, but, if so, we will receive another
+   * call to activateServer moments later and can update the AppDelegate again.
+   */
+  [self attachToAppDelegate];
+
+  /**
+   * Call the shared lifecycle object so it can evaluate the current state and figure out whether this is a real activation of
+   * the input method or a change in clients or a false alarm.
+   */
   [KMInputMethodLifecycle.shared activateClient:sender];
 }
 
+- (void)attachToAppDelegate {
+  self.appDelegate.inputController = self;
+}
+
+/**
+ * Called by the OS to deactivate the input method
+ */
 - (void)deactivateServer:(id)sender {
+  os_log_info([KMLogs lifecycleLog], " +++KMInputController, deactivateServer, self=%p", self);
+
+  /**
+   * Call the shared lifecycle object so it can evaluate the current state and figure out whether this is a real deactivation of
+   * the input method or a change in clients or a false alarm.
+   */
   [KMInputMethodLifecycle.shared deactivateClient:sender];
-  [[NSNotificationCenter defaultCenter] removeObserver:self];
 }
 
 - (NSMenu *)menu {

mac/Keyman4MacIM/Keyman4MacIM/KMInputMethodAppDelegate.m

@@ -123,15 +123,39 @@ - (void)initCompletion {
   // register to receive notifications generated from KMInputMethodLifecycle
   [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(inputMethodActivated:) name:kInputMethodActivatedNotification object:nil];
   [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(inputMethodDeactivated:) name:kInputMethodDeactivatedNotification object:nil];
+  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(inputMethodChangedClient:) name:kInputMethodClientChangeNotification object:nil];
 
   // start Input Method lifecycle
   [KMInputMethodLifecycle.shared startLifecycle];
 }
 
 /**
- * When the input method is deactivated, hide the OSK and disable the low-level event tap
+ * When the input method is activated -- notification from KMInputMethodLifecycle
+ */
+- (void)inputMethodActivated:(NSNotification *)notification {
+
+  // enable event tap
+  if (self.lowLevelEventTap && !CGEventTapIsEnabled(self.lowLevelEventTap)) {
+    os_log_debug([KMLogs lifecycleLog], "***KMInputMethodAppDelegate inputMethodActivated, re-enabling event tap...");
+    CGEventTapEnable(self.lowLevelEventTap, YES);
+  }
+
+  // show OSK if necessary
+  os_log_debug([KMLogs lifecycleLog], "--- inputMethodActivated, kvk is non-nil: %{public}@ showOskOnActivate: %{public}@", (_kvk!=nil)?@"true":@"false", [KMInputMethodLifecycle.shared shouldShowOskOnActivate]?@"true":@"false");
+
+  if ([KMInputMethodLifecycle.shared shouldShowOskOnActivate]) {
+    os_log_debug([KMLogs oskLog], "***KMInputMethodAppDelegate inputMethodActivated, showing OSK");
+    [KMSentryHelper addBreadCrumb:@"lifecycle" message:@"opening OSK on input method activation"];
+    [self showOSK];
+  }
+}
+
+/**
+ * When the input method is deactivated -- notification from KMInputMethodLifecycle
  */
 - (void)inputMethodDeactivated:(NSNotification *)notification {
+
+  // if the OSK is visible, hide it
   if ([self.oskWindow.window isVisible]) {
     os_log_debug([KMLogs oskLog], "***KMInputMethodAppDelegate inputMethodDeactivated, hiding OSK");
     [KMSentryHelper addBreadCrumb:@"lifecycle" message:@"hiding OSK on input method deactivation"];
@@ -141,28 +165,22 @@ - (void)inputMethodDeactivated:(NSNotification *)notification {
   }
   [KMSentryHelper addOskVisibleTag:[self.oskWindow.window isVisible]];
 
+  // disable the event tap
   if (self.lowLevelEventTap) {
     os_log_debug([KMLogs lifecycleLog], "***inputMethodDeactivated, disabling event tap");
     CGEventTapEnable(self.lowLevelEventTap, NO);
   }
+
+  // deactive the text input client
+  [self.inputController deactivateClient];
 }
 
 /**
- * When the input method is activated, show the OSK and enable the low-level event tap
+ * When the user switches to a different text input client -- notification from KMInputMethodLifecycle
  */
-- (void)inputMethodActivated:(NSNotification *)notification {
-  if (self.lowLevelEventTap && !CGEventTapIsEnabled(self.lowLevelEventTap)) {
-    os_log_debug([KMLogs lifecycleLog], "***KMInputMethodAppDelegate inputMethodActivated, re-enabling event tap...");
-    CGEventTapEnable(self.lowLevelEventTap, YES);
-  }
-
-  os_log_debug([KMLogs lifecycleLog], "--- inputMethodActivated, kvk is non-nil: %{public}@ showOskOnActivate: %{public}@", (_kvk!=nil)?@"true":@"false", [KMInputMethodLifecycle.shared shouldShowOskOnActivate]?@"true":@"false");
-
-  if ([KMInputMethodLifecycle.shared shouldShowOskOnActivate]) {
-    os_log_debug([KMLogs oskLog], "***KMInputMethodAppDelegate inputMethodActivated, showing OSK");
-    [KMSentryHelper addBreadCrumb:@"lifecycle" message:@"opening OSK on input method activation"];
-    [self showOSK];
-  }
+- (void)inputMethodChangedClient:(NSNotification *)notification {
+  os_log_debug([KMLogs lifecycleLog], "***KMInputMethodAppDelegate inputMethodChangedClient");
+  [self.inputController changeClients:[KMInputMethodLifecycle getRunningApplicationId]];
 }
 
 - (KeymanVersionInfo)versionInfo {