canvas里面图片如何获取（canvas生成带二维码海报的踩坑记录）

// 头像;
const imgAvadar = await promiseLoadImg(this.userInfoExternal.headUrl);
const imgSize = 40 * this.dpr;
const imgPos = 24 * this.dpr;

ctx.arc((this.canvas.width / 2), (imgPos + (imgSize / 2)), (imgSize / 2), 0, 2 * Math.PI);
ctx.clip();
ctx.drawImage(imgAvadar, ((this.canvas.width / 2) - (imgSize / 2)), imgPos, imgSize, imgSize);

new Promise(resolve => {
    const img = new Image();
    // base64添加了以下跨域配置，在低版本安卓中会不显示图片
    if (src.indexOf('base64,') === -1) {
        img.setAttribute('crossOrigin', 'Anonymous');
    }
    img.onload = function () {
        resolve(img);
    };
    img.src = src;
});