vue 截图转base64转文件File 异步获取

import html2canvas from "html2canvas";
export   function  base64ImgtoFile(dataurl, filename = 'file') {
    let arr = dataurl.split(',')
    let mime = arr[0].match(/:(.*?);/)[1]
    let suffix = mime.split('/')[1]
    let bstr = atob(arr[1])
    let n = bstr.length
    let u8arr = new Uint8Array(n)
    while (n--) {
      u8arr[n] = bstr.charCodeAt(n)
    }
    return new File([u8arr], `${filename}.${suffix}`, {
      type: mime
    })
  }
 
 
  export   function toImages(imageTofile) {
    return new Promise((resolve, reject) => {
      html2canvas(imageTofile, {
        backgroundColor: null,
        useCORS: true 
      }).then((canvas) => {
        const url = canvas.toDataURL('image/png');
          resolve(base64ImgtoFile(url))
      }).catch((err) => {
        reject(err)
      })
    })
  }
 

// 调用  

  toImage() {

      let that=this;

       toImages(this.$refs.imageTofile).then((imgFileRaw) => {

      that.imgFileRaw = base64ImgtoFile(this.htmlUrl);

    }).catch((error) => {

      that.imgFileRaw = null;

    });

    },