linkis-web/src/utils/watermark.js

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

let watermark = {}
let oldId = null;

let setWatermark = (text, sourceBody) => {
  if (document.getElementById(oldId) !== null) document.getElementById(oldId).parentNode.removeChild(document.getElementById(oldId))

  let id = Math.random()*10000+'-'+Math.random()*10000+'/'+Math.random()*10000
  oldId = id

  if (document.getElementById(id) !== null) {
    document.body.removeChild(document.getElementById(id))
  }
 
  let can = document.createElement('canvas')
  can.width = 300
  can.height = 150
 
  let cans = can.getContext('2d')
  cans.rotate(-20 * Math.PI / 180)
  cans.font = '14px Microsoft Yahei'
  cans.fillStyle = 'rgba(184, 184, 184, 0.2)'
  cans.textAlign = 'left'
  cans.textBaseline = 'Middle'
  cans.fillText(text, can.width / 20, can.height )
 
  let water_div = document.createElement('div')
  water_div.id = id
  water_div.style.pointerEvents = 'none'
  water_div.style.background = 'url(' + can.toDataURL('image/png') + ') left top repeat'
  if(sourceBody){
    water_div.style.width = '100%'
    water_div.style.height = '100%'
    sourceBody.appendChild(water_div)
  }else{
    water_div.style.top = '3px'
    water_div.style.left = '0px'
    water_div.style.position = 'fixed'
    water_div.style.zIndex = '100000'
    water_div.style.width = document.documentElement.clientWidth  + 'px'
    water_div.style.height = document.documentElement.clientHeight  + 'px'
    document.body.appendChild(water_div)
  }
 
  return id
}
 
/**
 *  该方法只允许调用一次
 *  @param:
 *  @text == 水印内容
 *  @sourceBody == 水印添加在哪里，不传就是body
 * */
watermark.set = (text, sourceBody) => {
  setWatermark(text, sourceBody)
  window.onresize = () => {
    setWatermark(text, sourceBody)
  }
}

watermark.clear = () => {
  if (document.getElementById(oldId) !== null) document.getElementById(oldId).parentNode.removeChild(document.getElementById(oldId))
}

export default watermark