我试图在我的应用程序中实现一个函数，这样用户就可以签署PDF文件。我在CodeSandbox上找到了一个签名板的示例，我试图将其插入到我的项目中，但我得到了2个错误，称为：

Property 'getTrimmedCanvas' does not exist on type '{}'.ts(2339)

Property 'clear' does not exist on type '{}'.ts(2339)

Codesource Signature Pad example

与错误一致

import Popup from "reactjs-popup";
import SignaturePad from "react-signature-canvas";
import { useState, useRef } from "react";
import React from "react";

function Button() {
  const sigCanvas = useRef({});
  const [imageURL, setImageURL] = useState(null);
  const clear = () => sigCanvas.current.clear();
  const save = () =>setImageURL(sigCanvas.current.getTrimmedCanvas().toDataURL("image/png"));

  return (

//for more Code use the Link: Codesource Signature Pad example

  );
}

export default Button;

我已经安装了这两个库：

npm install --save reactjs-popup
npm install --save react-signature-canvas

知道怎么修吗？谢谢