!230 add emitter.d.ts

Merge pull request !230 from zengsiyu/dev

api/@ohos.emitter.d.ts

@@ -0,0 +1,117 @@
+/*
+ * Copyright (c) 2021 Huawei Device Co., Ltd.
+ * 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.
+ */
+
+import { Callback } from './basic';
+
+/**
+ * Provides methods for sending and processing in-process events.
+ *
+ * @since 7
+ * @import import events_emitter from '@ohos.emitter';
+ * @permission N/A
+ */
+declare namespace emitter {
+  /**
+   * Subscribes to a certain event in persistent manner and receives the event callback.
+   *
+   * @since 7
+   * @param event indicate event to subscribe to.
+   * @param callback indicate callback used to receive the event.
+   * @return -
+   */
+  function on(event: InnerEvent, callback: Callback<EventData>): void;
+
+  /**
+   * Subscribes to a certain event in one-shot manner and unsubscribes from it
+   * after the event callback is received.
+   *
+   * @since 7
+   * @param event indicate event to subscribe to in one shot.
+   * @param callback indicate callback used to receive the event.
+   * @return -
+   */
+  function once(event: InnerEvent, callback: Callback<EventData>): void;
+
+  /**
+   * Unsubscribes from an event.
+   *
+   * @since 7
+   * @param eventId indicate ID of the event to unsubscribe from.
+   * @return -
+   */
+  function off(eventId: number): void;
+
+  /**
+   * Emits an event to the event queue.
+   *
+   * @since 7
+   * @param event indicate event to emit.
+   * @param data indicate data carried by the event.
+   * @return -
+   */
+  function emit(event: InnerEvent, data?: EventData): void;
+
+  /**
+   * Describes data passed in the event.
+   */
+  export interface EventData {
+    /**
+     * Data carried by the event.
+     */
+    data?: {[key: string]: any};
+  }
+
+  /**
+   * Describes an intra-process event.
+   */
+  export interface InnerEvent {
+    /**
+     * Event ID, which is used to identify an event.
+     */
+    eventId: number;
+
+    /**
+     * Emit priority of the event. The default priority is {@link EventPriority.LOW}.
+     */
+    priority?: EventPriority;
+  }
+
+  /**
+   * Indicates the emit priority of the event.
+   */
+  export enum EventPriority {
+    /**
+     * Indicates that the event will be emitted immediately.
+     */
+    IMMEDIATE = 0,
+
+    /**
+     * Indicates that the event will be emitted before low-priority events.
+     */
+    HIGH,
+
+    /**
+     * Indicates that the event will be emitted before idle-priority events. By default, an event is in LOW priority.
+     */
+    LOW,
+
+    /**
+     * Indicates that the event will be emitted after all the other events.
+     */
+    IDLE,
+  }
+}
+
+export default emitter;