Convert bunch of utils to TS

src/utils/ResizeNotifier.ts

@@ -0,0 +1,79 @@
+/*
+Copyright 2019 - 2021 The Matrix.org Foundation C.I.C.
+
+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.
+*/
+
+/**
+ * Fires when the middle panel has been resized (throttled).
+ * @event module:utils~ResizeNotifier#"middlePanelResized"
+ */
+/**
+ * Fires when the middle panel has been resized by a pixel.
+ * @event module:utils~ResizeNotifier#"middlePanelResizedNoisy"
+ */
+
+import { EventEmitter } from "events";
+import { throttle } from "lodash";
+
+export default class ResizeNotifier extends EventEmitter {
+    private _isResizing = false;
+
+    // with default options, will call fn once at first call, and then every x ms
+    // if there was another call in that timespan
+    private throttledMiddlePanel = throttle(() => this.emit("middlePanelResized"), 200);
+
+    public get isResizing() {
+        return this._isResizing;
+    }
+
+    public startResizing() {
+        this._isResizing = true;
+        this.emit("isResizing", true);
+    }
+
+    public stopResizing() {
+        this._isResizing = false;
+        this.emit("isResizing", false);
+    }
+
+    private noisyMiddlePanel() {
+        this.emit("middlePanelResizedNoisy");
+    }
+
+    private updateMiddlePanel() {
+        this.throttledMiddlePanel();
+        this.noisyMiddlePanel();
+    }
+
+    // can be called in quick succession
+    public notifyLeftHandleResized() {
+        // don't emit event for own region
+        this.updateMiddlePanel();
+    }
+
+    // can be called in quick succession
+    public notifyRightHandleResized() {
+        this.updateMiddlePanel();
+    }
+
+    public notifyTimelineHeightChanged() {
+        this.updateMiddlePanel();
+    }
+
+    // can be called in quick succession
+    public notifyWindowResized() {
+        this.updateMiddlePanel();
+    }
+}
+