Javascript 将Arrow函数转换为React.js中的类

我是react.js的新手。我需要实现构造函数和更多我在课堂上知道的函数。我试过了，但出现了

useRef

和

useCallback

错误。下面是我想将Arrow函数转换为类的代码。请帮助我，我对React.js非常陌生

const Webcams = () => {
  const webcamRef = React.useRef(null);

  const capture = React.useCallback(
    () => {

      const imageSrc = webcamRef.current.getScreenshot();
      console.log(imageSrc);
      image64 = imageSrc;
      var newImg = imageSrc.replace('data:image/jpeg;base64,', '');

      var rand = makeid(5)+'.jpg';

      const uploadTask = storage.ref(`images/${rand}`).putString(newImg,'base64');
      uploadTask.on('state_changed',
      (snapshot) => {

        const progress = Math.round((snapshot.bytesTransferred / snapshot.totalBytes) * 100);
        console.log(progress);
      },
      (error) => {

        console.log(error);
      },
      () => {

        storage.ref('images').child(rand).getDownloadURL().then(url => {
            console.log(url);

            firebase
            .firestore()
            .collection('notes')
            .add({
              url: url
            })
            .then(() => {
               console.log('Finished');
            })
        })
      });
    },
    [webcamRef]
  );

  const show = React.useCallback(
    () => {

      var f = document.getElementById('flash');
         setTimeout(function() {
            f.style.display = (f.style.display == 'none' ? '' : 'show');
         }, 100);
    },
  );

  return (
    <div>
    <div id="flash"> </div>
    <div className="web">
      <Webcam
        audio={false}
        height={400}
        ref={webcamRef}
        screenshotFormat="image/jpeg"
        width={400}
        videoConstraints={videoConstraints}
      />
      <span><button onClick={capture}></button></span>
      </div>

      </div>

  );
};

import React，{Component}来自'React'；
类欢迎扩展组件{
建造师（道具）{
超级（道具）；
this.webcamRef=React.createRef（）；
}
捕获=（）=>{
const imageSrc=this.webcamRef.current.getScreenshot（）；
...
}
show=（）=>{
...
}
render（）{
返回(
);
}
}

您需要导入React

import React, { Component } from 'react';

import React, { Component } from 'react';