一开始用print.js打印包含canvas的dom，后来，查了资料，对print.js修改后，可以很好的解决了问题，但是没有自适应打印纸张。没找到好办法，那就自己改一下吧。

基本print.js的基础上将代码进行修改，将需要打印的dom转为图片后，调用print.js将图片进行打印。

main.js

import Print from './plugins/print'
Vue.use(Print) // 注册

print.js

import html2canvas from "html2canvas"

// 打印类属性、方法定义
/* eslint-disable */
const Print = function (dom, options) {
  if (!(this instanceof Print)) return new Print(dom, options);

  this.options = this.extend({
    'noPrint': '.no-print'
  }, options);
  
  if ((typeof dom) === "string") {
    this.cloneDom = document.querySelector(dom);
  } else {
    this.isDOM(dom)
    this.cloneDom = this.isDOM(dom) ? dom : dom.$el;
  }

  //主要修改：将打印的dom转换成图片
  html2canvas(this.cloneDom).then(canvas => {
      this.imgmap = canvas.toDataURL()
      setTimeout(()=>{
          this.dom = `<div style='width:100%;height:100%;'><img style='width:100%;height:auto;' src='${this.imgmap}'/></div>`
          this.init();
      })
  })
};
Print.prototype = {
  init: function () {
    var content = this.dom;
    this.writeIframe(content);
  },
  extend: function (obj, obj2) {
    for (var k in obj2) {
      obj[k] = obj2[k];
    }
    return obj;
  },

  writeIframe: function (content) {
    var w, doc, iframe = document.createElement('iframe'),
      f = document.body.appendChild(iframe);
    iframe.id = "myIframe";
    //iframe.style = "position:absolute;width:0;height:0;top:-10px;left:-10px;";
    iframe.setAttribute('style', 'position:absolute;width:0;height:0;top:-10px;left:-10px;');
    w = f.contentWindow || f.contentDocument;
    doc = f.contentDocument || f.contentWindow.document;
    doc.open();
    doc.write(content);
    doc.close();
    var _this = this
    iframe.onload = function(){
      _this.toPrint(w);
      setTimeout(function () {
        document.body.removeChild(iframe)
      }, 100)
    }
  },

  toPrint: function (frameWindow) {
    try {
      setTimeout(function () {
        frameWindow.focus();
        try {
          if (!frameWindow.document.execCommand('print', false, null)) {
            frameWindow.print();
          }
        } catch (e) {
          frameWindow.print();
        }
        frameWindow.close();
      }, 10);
    } catch (err) {
      console.log('err', err);
    }
  },
  isDOM: (typeof HTMLElement === 'object') ?
    function (obj) {
      return obj instanceof HTMLElement;
    } :
    function (obj) {
      return obj && typeof obj === 'object' && obj.nodeType === 1 && typeof obj.nodeName === 'string';
    }
};
const MyPlugin = {}
MyPlugin.install = function (Vue, options) {
  // 4. 添加实例方法
  Vue.prototype.$print = Print
}
export default MyPlugin

调用

this.$print(this.$refs.print)