Add spatial audio capabilities

src/settings/useSetting.ts

@@ -0,0 +1,56 @@
+/*
+Copyright 2022 New Vector 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 { EventEmitter } from "events";
+import { useMemo, useState, useEffect, useCallback } from "react";
+
+// Bus to notify other useSetting consumers when a setting is changed
+const settingsBus = new EventEmitter();
+
+// Like useState, but reads from and persists the value to localStorage
+const useSetting = <T>(
+  name: string,
+  defaultValue: T
+): [T, (value: T) => void] => {
+  const key = useMemo(() => `matrix-setting-${name}`, [name]);
+
+  const [value, setValue] = useState<T>(() => {
+    const item = localStorage.getItem(key);
+    return item == null ? defaultValue : JSON.parse(item);
+  });
+
+  useEffect(() => {
+    settingsBus.on(name, setValue);
+    return () => {
+      settingsBus.off(name, setValue);
+    };
+  }, [name, setValue]);
+
+  return [
+    value,
+    useCallback(
+      (newValue: T) => {
+        setValue(newValue);
+        localStorage.setItem(key, JSON.stringify(newValue));
+        settingsBus.emit(name, newValue);
+      },
+      [name, key, setValue]
+    ),
+  ];
+};
+
+export const useSpatialAudio = () => useSetting("spatial-audio", false);
+export const useShowInspector = () => useSetting("show-inspector", false);