移动端Vue+Vant的Uploader实现上传、压缩、旋转图片功能

data() {
    return {
      files: {
        name: "",
        type: ""
      },
      headerImage: null,
      picValue: null,
      upImgUrl,
    }
  },
  // 组件方法 获取 流
  async onRead(file) {
      // console.log(file);
      // console.log(file.file);
      this.files.name = file.file.name; // 获取文件名
      this.files.type = file.file.type; // 获取类型
      this.picValue = file.file; // 文件流
      this.imgPreview(this.picValue);
    },
    // 处理图片
    imgPreview(file) {
      let self = this;
      let Orientation;
      //去获取拍照时的信息，解决拍出来的照片旋转问题
      Exif.getData(file, function () {
        Orientation = Exif.getTag(this, "Orientation");
      });
      // 看支持不支持FileReader
      if (!file || !window.FileReader) return;
      if (/^image/.test(file.type)) {
        // 创建一个reader
        let reader = new FileReader();
        // 将图片2将转成 base64 格式
        reader.readAsDataURL(file);
        // 读取成功后的回调
        reader.Onloadend= function () {
          // console.log(this.result);
          let result = this.result;
          let img = new Image();
          img.src = result;
          //判断图片是否大于500K,是就直接上传，反之压缩图片
          if (this.result.length <= 500 * 1024) {
            self.headerImage = this.result;
            self.postImg();
          } else {
            img.Onload= function () {
              let data = self.compress(img, Orientation);
              self.headerImage = data;
              self.postImg();
            };
          }
        };
      }
    },
    // 压缩图片
    compress(img, Orientation) {
      let canvas = document.createElement("canvas");
      let ctx = canvas.getContext("2d");
      //瓦片canvas
      let tCanvas = document.createElement("canvas");
      let tctx = tCanvas.getContext("2d");
      // let initSize = img.src.length;
      let width = img.width;
      let height = img.height;
      //如果图片大于四百万像素，计算压缩比并将大小压至400万以下
      let ratio;
      if ((ratio = (width * height) / 4000000) > 1) {
        // console.log("大于400万像素");
        ratio = Math.sqrt(ratio);
        width /= ratio;
        height /= ratio;
      } else {
        ratio = 1;
      }
      canvas.width = width;
      canvas.height = height;
      //    铺底色
      ctx.fillStyle = "#fff";
      ctx.fillRect(0, 0, canvas.width, canvas.height);
      //如果图片像素大于100万则使用瓦片绘制
      let count;
      if ((count = (width * height) / 1000000) > 1) {
        // console.log("超过100W像素");
        count = ~~(Math.sqrt(count) + 1); //计算要分成多少块瓦片
        //      计算每块瓦片的宽和高
        let nw = ~~(width / count);
        let nh = ~~(height / count);
        tCanvas.width = nw;
        tCanvas.height = nh;
        for (let i = 0; i  max_step && (step = min_step);
      } else {
        step--;
        step