Vue获取file图片的宽高

<el-upload
    v-model:file-list="waitFileList"
    list-type="picture-card"
    action="/"
    multiple
    :before-upload="handleBeforeUpload"
    :http-request="handleHttpRequest"
    :on-preview="handlePictureCardPreview"
    :on-remove="handleRemove"
>

handleBeforeUpload(file) {
      if (file) {
        function getFileData(file) {
          return new Promise(function (resolve, reject) {
            let reader = new FileReader()
            reader.readAsDataURL(file);
            reader.onload = function (event) {

              resolve(reader.result)
            }
          })
        }
        function getImage(result) {
          return new Promise(function (resolve, reject) {
            let img = new Image();
            img.src = result;
            img.onload = function () { //注意只有onload以后才可以拿到图片信息
              resolve({
                width: img.width,
                height: img.height
              })
            }
          })
        }
        getFileData(file).then(res => {
          getImage(res).then(r=>{
            this.compressImageParam.afterFileHeight=r.height
            this.compressImageParam.afterFileWidth=r.width
          })
        })
      }