Import of the watch repository from Pebble

src/fw/applib/app_focus_service.c

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "app_focus_service.h"
+
+#include "event_service_client.h"
+#include "process_state/app_state/app_state.h"
+#include "services/common/event_service.h"
+
+static void prv_focus_event_handler(PebbleEvent *e, void *context) {
+  AppFocusState *state = app_state_get_app_focus_state();
+  bool in_focus = e->app_focus.in_focus;
+  if (e->type == PEBBLE_APP_WILL_CHANGE_FOCUS_EVENT &&
+      state->handlers.will_focus) {
+    state->handlers.will_focus(in_focus);
+  } else if (e->type == PEBBLE_APP_DID_CHANGE_FOCUS_EVENT &&
+             state->handlers.did_focus) {
+    state->handlers.did_focus(in_focus);
+  }
+}
+
+void app_focus_service_subscribe_handlers(AppFocusHandlers handlers) {
+  AppFocusState *state = app_state_get_app_focus_state();
+
+  app_focus_service_unsubscribe();
+  if (handlers.did_focus) {
+    // NOTE: the individual fields of state->did_focus_info are assigned
+    // to instead of writing
+    //     state->did_focus_info = (EventServiceInfo) { ... }
+    // as the latter would zero out the ListNode embedded in the struct.
+    // Doing so would corrupt the events list if the event was already
+    // subscribed.
+    state->did_focus_info.type = PEBBLE_APP_DID_CHANGE_FOCUS_EVENT;
+    state->did_focus_info.handler = prv_focus_event_handler;
+    event_service_client_subscribe(&state->did_focus_info);
+  }
+  if (handlers.will_focus) {
+    state->will_focus_info.type = PEBBLE_APP_WILL_CHANGE_FOCUS_EVENT;
+    state->will_focus_info.handler = prv_focus_event_handler;
+    event_service_client_subscribe(&state->will_focus_info);
+  }
+  state->handlers = handlers;
+}
+
+void app_focus_service_subscribe(AppFocusHandler handler) {
+  AppFocusHandlers handlers = (AppFocusHandlers) { .will_focus = handler };
+  app_focus_service_subscribe_handlers(handlers);
+}
+
+void app_focus_service_unsubscribe(void) {
+  AppFocusState *state = app_state_get_app_focus_state();
+  if (state->handlers.will_focus) {
+    event_service_client_unsubscribe(&state->will_focus_info);
+  }
+  if (state->handlers.did_focus) {
+    event_service_client_unsubscribe(&state->did_focus_info);
+  }
+  state->handlers = (AppFocusHandlers) {};
+}