Vue实现页面添加水印功能

let watermark = {}

let setWatermark = (str) => {
 let id = '1.23452384164.123412416';

 if (document.getElementById(id) !== null) {
 document.body.removeChild(document.getElementById(id));
 }

 //创建一个画布
 let can = document.createElement('canvas');
 //设置画布的长宽
 can.width = 120;
 can.height = 120;

 let cans = can.getContext('2d');
 //旋转角度
 cans.rotate(-15 * Math.PI / 180);
 cans.font = '18px Vedana';
 //设置填充绘画的颜色、渐变或者模式
 cans.fillStyle = 'rgba(200, 200, 200, 0.40)';
 //设置文本内容的当前对齐方式
 cans.textAlign = 'left';
 //设置在绘制文本时使用的当前文本基线
 cans.textBaseline = 'Middle';
 //在画布上绘制填色的文本（输出的文本，开始绘制文本的X坐标位置，开始绘制文本的Y坐标位置）
 cans.fillText(str, can.width / 8, can.height / 2);

 let div = document.createElement('div');
 div.id = id;
 div.style.pointerEvents = 'none';
 div.style.top = '30px';
 div.style.left = '0px';
 div.style.position = 'fixed';
 div.style.zIndex = '100000';
 div.style.width = document.documentElement.clientWidth + 'px';
 div.style.height = document.documentElement.clientHeight + 'px';
 div.style.background = 'url(' + can.toDataURL('image/png') + ') left top repeat';
 document.body.appendChild(div);
 return id;
}

// 该方法只允许调用一次
watermark.set = (str) => {
 let id = setWatermark(str);
 setInterval(() => {
 if (document.getElementById(id) === null) {
  id = setWatermark(str);
 }
 }, 500);
 window.onresize = () => {
 setWatermark(str);
 };
}

export default watermark;

import Watermark from '@/common/js/watermark'; //路径不要写错

mounted: function () {
 Watermark.set("水印内容")
}

router.beforeEach((to, from, next) => {
 // 登录判断
 store.dispatch('getuser').then((user) => {
 if (to.path === '/') {
  if (user.isLeader) {
  next('/Summary');
  } else { next('/list'); }
 } else {
  next();
 }
 }).catch((error) => {
 if (error.message === 'noUser') {
  //返回登录界面
 } else {
  Dialog.confirm({
  title: '服务器错误',
  message: '获取用户信息失败,可尝试重新进入系统。',
  showCancelButton: false,
  showConfirmButton: false
  });
 }
 });
});
router.afterEach((to) => {
 /* 路由发生变化修改页面title */
 if (to.meta.title) {
 changTitle(to.meta.title);
 }
 Watermark.set(store.state.user.userId);
});