完美解决canvas跨域

1.创建canvas

 getxjb() {
      this.$nextTick(() => {
        this.mycan = document.getElementById("myCanvas");

        var ctx = this.mycan.getContext("2d");
        var img = new Image();
        img.src = require("../../assets/images/yq.png"); //获取本地图片 必须用 require

        var img2 = new Image();
        img2.src = "http://" + this.getInviteInfo_data.downCode.codeImgAndroid;

        img2.setAttribute("crossOrigin", "anonymous");
        img.onload = () => {
       		//图片加载完毕后再进行
          img2.onload = () => {
            ctx.drawImage(img, 0, 0, 375, 672);
            ctx.drawImage(img2, 107, 330, 160, 160);
            ctx.fillStyle = "#fff";
            ctx.font = "20px Arial ";
            ctx.fillText(this.getInviteInfo_data.invitation_code, 145, 520);
          };
        };
      });
    },

2.保存为图片

 toImage() {
    
    
      var canvas = document.getElementById("myCanvas");
      var image = new Image();

      image.src = canvas.toDataURL("image/png");
      //动态创建a标签并出发a的下载时间
      let a = document.createElement("a");
      a.download = "invitation";
      a.href = image.src;
      a.click();
    },

3.canvas 图片跨域，无法保存为图片

[解决方法](https://www.jianshu.com/p/436caf91dd06)

github地址
https://github.com/h5bp/server-configs-apache/blob/fc379c45f52a09dd41279dbf4e60ae281110a5b0/src/.htaccess#L36-L53