canvas实现二维码和图片合成的示例代码

import React, { Component } from &#39;react&#39;const qrcode = require(&#39;jr-qrcode&#39;)const loadImg = (src) => {    const paths = Array.isArray(src) ? src : [src];    const promise = [];    paths.forEach((path) => {        promise.push(new Promise((resolve, reject) => {            let img = new Image();            img.crossOrigin = "Anonymous";            img.src = path;            img.onload = () => {                resolve(img);            };            img.onerror = (err) => {                console.log(&#39;图片加载失败&#39;)            }        }))    });    return Promise.all(promise);}const getImageData = (url, src) => {    const imgsrc = qrcode.getQrBase64(url)    let canvas = document.createElement(&#39;canvas&#39;)    const width = document.documentElement.clientWidth    const height = document.documentElement.clientHeight    canvas.width = width*2    canvas.height = height*2    let ctx = canvas.getContext("2d")     loadImg([imgsrc, src]).then(([img1, img2]) => {        ctx.drawImage(img2, 0, 0, width*2, height*2)        ctx.drawImage(img1, width-80, height*2-220, 200, 160)        ctx.fillStyle = &#39;rgba(0,0,0,0.3)&#39;;        ctx.fillRect(width-80, height*2-60, 200, 40);        ctx.save()        ctx.font="28px Arial"        ctx.fillStyle = &#39;#fff&#39;;        ctx.fillText(&#39;长按识别二维码&#39;, width-80, height*2-30, 200, 160)        let imageURL = canvas.toDataURL("image/png")        document.getElementById(&#39;mix_img&#39;).setAttribute(&#39;src&#39;,imageURL)    })}export default class QRcode extends Component {    render() {        const { url , picSrc} = this.props        getImageData(url,picSrc)        return (            <p>                <img  alt=&#39;mix_img&#39; id=&#39;mix_img&#39;/>            </p>        )    }}