Initial SpaceRoomView work

src/hooks/useStateArray.ts

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+/*
+Copyright 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.
+*/
+
+import {useState} from "react";
+
+// Hook to simplify managing state of arrays of a common type
+export const useStateArray = <T>(initialSize: number, initialState: T | T[]): [T[], (i: number, v: T) => void] => {
+    const [data, setData] = useState<T[]>(() => {
+        return Array.isArray(initialState) ? initialState : new Array(initialSize).fill(initialState);
+    });
+    return [data, (index: number, value: T) => setData(data => {
+        const copy = [...data];
+        copy[index] = value;
+        return copy;
+    })]
+};