excalidraw/examples/excalidraw/utils.ts

import { unstable_batchedUpdates } from "react-dom";
import { fileOpen as _fileOpen } from "browser-fs-access";
import { MIME_TYPES } from "@excalidraw/excalidraw";
import { AbortError } from "../../packages/excalidraw/errors";

type FILE_EXTENSION = Exclude<keyof typeof MIME_TYPES, "binary">;

const INPUT_CHANGE_INTERVAL_MS = 500;

export type ResolvablePromise<T> = Promise<T> & {
  resolve: [T] extends [undefined] ? (value?: T) => void : (value: T) => void;
  reject: (error: Error) => void;
};
export const resolvablePromise = <T>() => {
  let resolve!: any;
  let reject!: any;
  const promise = new Promise((_resolve, _reject) => {
    resolve = _resolve;
    reject = _reject;
  });
  (promise as any).resolve = resolve;
  (promise as any).reject = reject;
  return promise as ResolvablePromise<T>;
};

export const distance2d = (x1: number, y1: number, x2: number, y2: number) => {
  const xd = x2 - x1;
  const yd = y2 - y1;
  return Math.hypot(xd, yd);
};

export const fileOpen = <M extends boolean | undefined = false>(opts: {
  extensions?: FILE_EXTENSION[];
  description: string;
  multiple?: M;
}): Promise<M extends false | undefined ? File : File[]> => {
  // an unsafe TS hack, alas not much we can do AFAIK
  type RetType = M extends false | undefined ? File : File[];

  const mimeTypes = opts.extensions?.reduce((mimeTypes, type) => {
    mimeTypes.push(MIME_TYPES[type]);

    return mimeTypes;
  }, [] as string[]);

  const extensions = opts.extensions?.reduce((acc, ext) => {
    if (ext === "jpg") {
      return acc.concat(".jpg", ".jpeg");
    }
    return acc.concat(`.${ext}`);
  }, [] as string[]);

  return _fileOpen({
    description: opts.description,
    extensions,
    mimeTypes,
    multiple: opts.multiple ?? false,
    legacySetup: (resolve, reject, input) => {
      const scheduleRejection = debounce(reject, INPUT_CHANGE_INTERVAL_MS);
      const focusHandler = () => {
        checkForFile();
        document.addEventListener("keyup", scheduleRejection);
        document.addEventListener("pointerup", scheduleRejection);
        scheduleRejection();
      };
      const checkForFile = () => {
        // this hack might not work when expecting multiple files
        if (input.files?.length) {
          const ret = opts.multiple ? [...input.files] : input.files[0];
          resolve(ret as RetType);
        }
      };
      requestAnimationFrame(() => {
        window.addEventListener("focus", focusHandler);
      });
      const interval = window.setInterval(() => {
        checkForFile();
      }, INPUT_CHANGE_INTERVAL_MS);
      return (rejectPromise) => {
        clearInterval(interval);
        scheduleRejection.cancel();
        window.removeEventListener("focus", focusHandler);
        document.removeEventListener("keyup", scheduleRejection);
        document.removeEventListener("pointerup", scheduleRejection);
        if (rejectPromise) {
          // so that something is shown in console if we need to debug this
          console.warn("Opening the file was canceled (legacy-fs).");
          rejectPromise(new AbortError());
        }
      };
    },
  }) as Promise<RetType>;
};

export const debounce = <T extends any[]>(
  fn: (...args: T) => void,
  timeout: number,
) => {
  let handle = 0;
  let lastArgs: T | null = null;
  const ret = (...args: T) => {
    lastArgs = args;
    clearTimeout(handle);
    handle = window.setTimeout(() => {
      lastArgs = null;
      fn(...args);
    }, timeout);
  };
  ret.flush = () => {
    clearTimeout(handle);
    if (lastArgs) {
      const _lastArgs = lastArgs;
      lastArgs = null;
      fn(..._lastArgs);
    }
  };
  ret.cancel = () => {
    lastArgs = null;
    clearTimeout(handle);
  };
  return ret;
};

export const withBatchedUpdates = <
  TFunction extends ((event: any) => void) | (() => void),
>(
  func: Parameters<TFunction>["length"] extends 0 | 1 ? TFunction : never,
) =>
  ((event) => {
    unstable_batchedUpdates(func as TFunction, event);
  }) as TFunction;

/**
 * barches React state updates and throttles the calls to a single call per
 * animation frame
 */
export const withBatchedUpdatesThrottled = <
  TFunction extends ((event: any) => void) | (() => void),
>(
  func: Parameters<TFunction>["length"] extends 0 | 1 ? TFunction : never,
) => {
  // @ts-ignore
  return throttleRAF<Parameters<TFunction>>(((event) => {
    unstable_batchedUpdates(func, event);
  }) as TFunction);
};