页面简单水印输出方法

记录开发过程中实际运用案例(四)
原文地址：https://github.com/saucxs/watermark-dom
只是简单的加一个很浅的水印，实现起来很容易。不需要引入jquery插件。
(1) 获取组件，watermark.js是必须要引进的组件（下方代码会贴出来，也可通过该链接取https://github.com/saucxs/watermark-dom.git）
(2) 在需要加水印的相关页面引入水印文件"watermark.js

<script type="text/javascript" src="./watermark.js"></script>

(3) 在确保页面DOM加载完毕之后

window.onload = function(){
	watermark.init({ watermark_txt: "测试水印XXXXX" , watermark_width: 200});
}

watermark.js

(function (root,factory) {
  if (typeof define === 'function' && define.amd) {
    /*AMD. Register as an anonymous module.
    *define([], factory); */
    define([], factory());
  } else if (typeof module === 'object' && module.exports) {
    /*Node. Does not work with strict CommonJS, but
    // only CommonJS-like environments that support module.exports,
    // like Node.*/
    module.exports = factory();

  } else {
    /*Browser globals (root is window)*/
    root['watermark'] = factory();
  }
}(this, function () {

  /*Just return a value to define the module export.*/
  var watermark = {};

  var defaultSettings={
    watermark_id: 'wm_div_id',          //水印总体的id
    watermark_prefix: 'mask_div_id',    //小水印的id前缀
    watermark_txt:"XXXXXX",             //水印的内容
    watermark_x:20,                     //水印起始位置x轴坐标
    watermark_y:20,                     //水印起始位置Y轴坐标
    watermark_rows:0,                   //水印行数
    watermark_cols:0,                   //水印列数
    watermark_x_space:50,              //水印x轴间隔
    watermark_y_space:50,               //水印y轴间隔
    watermark_font:'微软雅黑',           //水印字体
    watermark_color:'black',            //水印字体颜色
    watermark_fontsize:'18px',          //水印字体大小
    watermark_alpha:0.15,               //水印透明度，要求设置在大于等于0.005
    watermark_width:100,                //水印宽度
    watermark_height:100,               //水印长度
    watermark_angle:15,                 //水印倾斜度数
    watermark_parent_width:0,      //水印的总体宽度（默认值：body的scrollWidth和clientWidth的较大值）
    watermark_parent_height:0,     //水印的总体高度（默认值：body的scrollHeight和clientHeight的较大值）
    watermark_parent_node:null,     //水印插件挂载的父元素element,不输入则默认挂在body上
    monitor:true,                   //monitor 是否监控， true: 不可删除水印; false: 可删水印。
  };


  /*加载水印*/
  var loadMark = function(settings) {
    /*采用配置项替换默认值，作用类似jquery.extend*/
    if(arguments.length===1&&typeof arguments[0] ==="object" ){
      var src=arguments[0]||{};
      for(key in src)
      {
        if(src[key]&&defaultSettings[key]&&src[key]===defaultSettings[key])continue;
        /*veronic: resolution of watermark_angle=0 not in force*/
        else if(src[key] || src[key] === 0) defaultSettings[key]=src[key];
      }
    }

    /*如果元素存在则移除*/
    var watermark_element = document.getElementById(defaultSettings.watermark_id);
    watermark_element && watermark_element.parentNode && watermark_element.parentNode.removeChild(watermark_element);

    /*如果设置水印挂载的父元素的id*/
    var watermark_parent_element = document.getElementById(defaultSettings.watermark_parent_node);
    var watermark_hook_element = watermark_parent_element ? watermark_parent_element : document.body;

    /*获取页面宽度*/
    // var page_width = Math.max(watermark_hook_element.scrollWidth,watermark_hook_element.clientWidth) - defaultSettings.watermark_width/2;
    var page_width = Math.max(watermark_hook_element.scrollWidth,watermark_hook_element.clientWidth);
    /*获取页面最大长度*/
    // var page_height = Math.max(watermark_hook_element.scrollHeight,watermark_hook_element.clientHeight,document.documentElement.clientHeight)-defaultSettings.watermark_height/2;
    var page_height = Math.max(watermark_hook_element.scrollHeight,watermark_hook_element.clientHeight);

    var setting = arguments[0]||{};
    var parentEle = watermark_hook_element;

    var page_offsetTop = 0;
    var page_offsetLeft = 0;
    if(setting.watermark_parent_width || setting.watermark_parent_height){
      /*指定父元素同时指定了宽或高*/
      if(parentEle){
        page_offsetTop = parentEle.offsetTop || 0;
        page_offsetLeft = parentEle.offsetLeft || 0;
        defaultSettings.watermark_x = defaultSettings.watermark_x + page_offsetLeft;
        defaultSettings.watermark_y = defaultSettings.watermark_y + page_offsetTop;
      }
    }else{
      if(parentEle){
        page_offsetTop = parentEle.offsetTop || 0;
        page_offsetLeft = parentEle.offsetLeft || 0;
      }
    }

    /*创建水印外壳div*/
    var otdiv = document.getElementById(defaultSettings.watermark_id);
    var shadowRoot=null;

    if(!otdiv){
      otdiv =document.createElement('div');
      /*创建shadow dom*/
      otdiv.id = defaultSettings.watermark_id;
      otdiv.setAttribute('style','pointer-events: none !important; display: block !important');
      /*判断浏览器是否支持attachShadow方法*/
      if(typeof otdiv.attachShadow === 'function'){
        /* createShadowRoot Deprecated. Not for use in new websites. Use attachShadow*/
        shadowRoot = otdiv.attachShadow({mode: 'open'});
      }else{
        shadowRoot = otdiv;
      }
      /*将shadow dom随机插入body内的任意位置*/
      var nodeList = watermark_hook_element.children;
      var index = Math.floor(Math.random()*(nodeList.length-1 ));
      if(nodeList[index]){
        watermark_hook_element.insertBefore(otdiv, nodeList[index]);
      }else{
        watermark_hook_element.appendChild(otdiv);
      }
    }else if (otdiv.shadowRoot){
      shadowRoot = otdiv.shadowRoot;
    }
    /*三种情况下会重新计算水印列数和x方向水印间隔：1、水印列数设置为0，2、水印宽度大于页面宽度，3、水印宽度小于于页面宽度*/
    defaultSettings.watermark_cols = parseInt((page_width - defaultSettings.watermark_x) / (defaultSettings.watermark_width + defaultSettings.watermark_x_space));
    var temp_watermark_x_space = parseInt((page_width - defaultSettings.watermark_x - defaultSettings.watermark_width * defaultSettings.watermark_cols) / (defaultSettings.watermark_cols));
    defaultSettings.watermark_x_space = temp_watermark_x_space? defaultSettings.watermark_x_space : temp_watermark_x_space;
    var allWatermarkWidth;

    /*三种情况下会重新计算水印行数和y方向水印间隔：1、水印行数设置为0，2、水印长度大于页面长度，3、水印长度小于于页面长度*/
    defaultSettings.watermark_rows = parseInt((page_height - defaultSettings.watermark_y) / (defaultSettings.watermark_height + defaultSettings.watermark_y_space));
    var temp_watermark_y_space = parseInt((page_height - defaultSettings.watermark_y - defaultSettings.watermark_height * defaultSettings.watermark_rows) / (defaultSettings.watermark_rows));
    defaultSettings.watermark_y_space = temp_watermark_y_space? defaultSettings.watermark_y_space : temp_watermark_y_space;
    var allWatermarkHeight;

    if(watermark_parent_element){
      allWatermarkWidth = defaultSettings.watermark_x + defaultSettings.watermark_width * defaultSettings.watermark_cols + defaultSettings.watermark_x_space * (defaultSettings.watermark_cols - 1);
      allWatermarkHeight = defaultSettings.watermark_y + defaultSettings.watermark_height * defaultSettings.watermark_rows + defaultSettings.watermark_y_space * (defaultSettings.watermark_rows - 1);
    }else{
      allWatermarkWidth = page_offsetLeft + defaultSettings.watermark_x + defaultSettings.watermark_width * defaultSettings.watermark_cols + defaultSettings.watermark_x_space * (defaultSettings.watermark_cols - 1);
      allWatermarkHeight = page_offsetTop + defaultSettings.watermark_y + defaultSettings.watermark_height * defaultSettings.watermark_rows + defaultSettings.watermark_y_space * (defaultSettings.watermark_rows - 1);
    }

    var x;
    var y;
    for (var i = 0; i < defaultSettings.watermark_rows; i++) {
      if(watermark_parent_element){
        y = page_offsetTop + defaultSettings.watermark_y + (page_height - allWatermarkHeight) / 2 + (defaultSettings.watermark_y_space + defaultSettings.watermark_height) * i;
      }else{
        y = defaultSettings.watermark_y + (page_height - allWatermarkHeight) / 2 + (defaultSettings.watermark_y_space + defaultSettings.watermark_height) * i;
      }
      for (var j = 0; j < defaultSettings.watermark_cols; j++) {
        if(watermark_parent_element){
          x = page_offsetLeft + defaultSettings.watermark_x + (page_width - allWatermarkWidth) / 2 + (defaultSettings.watermark_width + defaultSettings.watermark_x_space) * j;
        }else {
          x = defaultSettings.watermark_x + (page_width - allWatermarkWidth) / 2 + (defaultSettings.watermark_width + defaultSettings.watermark_x_space) * j;
        }
        var mask_div = document.createElement('div');
        var oText=document.createTextNode(defaultSettings.watermark_txt);
        mask_div.appendChild(oText);
        /*设置水印相关属性start*/
        mask_div.id = defaultSettings.watermark_prefix + i + j;
        /*设置水印div倾斜显示*/
        mask_div.style.webkitTransform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
        mask_div.style.MozTransform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
        mask_div.style.msTransform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
        mask_div.style.OTransform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
        mask_div.style.transform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
        mask_div.style.visibility = "";
        mask_div.style.position = "absolute";
        /*选不中*/
        mask_div.style.left = x + 'px';
        mask_div.style.top = y + 'px';
        mask_div.style.overflow = "hidden";
        mask_div.style.zIndex = "9999999";
        mask_div.style.opacity = defaultSettings.watermark_alpha;
        mask_div.style.fontSize = defaultSettings.watermark_fontsize;
        mask_div.style.fontFamily = defaultSettings.watermark_font;
        mask_div.style.color = defaultSettings.watermark_color;
        mask_div.style.textAlign = "center";
        mask_div.style.width = defaultSettings.watermark_width + 'px';
        mask_div.style.height = defaultSettings.watermark_height + 'px';
        mask_div.style.display = "block";
        mask_div.style['-ms-user-select'] = "none";
        /*设置水印相关属性end*/
        shadowRoot.appendChild(mask_div);
      }
    }

    // monitor 是否监控， true: 不可删除水印; false: 可删水印。
    const minotor = settings.monitor === undefined ? defaultSettings.monitor : settings.monitor;
    if (minotor) {
      watermarkDom.observe(watermark_hook_element, option);
      watermarkDom.observe(document.getElementById(defaultSettings.watermark_id).shadowRoot, option);
    }
  };

  /*移除水印*/
  var removeMark = function() {
    /*采用配置项替换默认值，作用类似jquery.extend*/
    if(arguments.length===1&&typeof arguments[0] ==="object" )
    {
      var src=arguments[0]||{};
      for(key in src)
      {
        if(src[key]&&defaultSettings[key]&&src[key]===defaultSettings[key])continue;
        /*veronic: resolution of watermark_angle=0 not in force*/
        else if(src[key] || src[key] === 0) defaultSettings[key]=src[key];
      }
    }

    /*移除水印*/
    var watermark_element = document.getElementById(defaultSettings.watermark_id);
    var _parentElement = watermark_element.parentNode;
    _parentElement.removeChild(watermark_element);
  };

  var globalSetting;
  /*初始化水印，添加load和resize事件*/
  watermark.init = function(settings) {
    globalSetting = settings;
    loadMark(settings);
    window.addEventListener('onload', function () {
      loadMark(settings);
    });
    window.addEventListener('resize', function () {
      loadMark(settings);
    });
  };

  /*手动加载水印*/
  watermark.load = function(settings){
    globalSetting = settings;
    loadMark(settings);
  };

  /*手动移除水印*/
  watermark.remove = function(){
    removeMark();
  };

  //监听dom是否被移除或者改变属性的回调函数
  var callback = function (records){
    if ((globalSetting && records.length === 1) || records.length === 1 && records[0].removedNodes.length >= 1) {
      loadMark(globalSetting);
    }
  };
  const MutationObserver = window.MutationObserver || window.WebKitMutationObserver || window.MozMutationObserver;
  var watermarkDom = new MutationObserver(callback);
  var option = {
    'childList': true,
    'attributes': true,
    'subtree': true,
  };

  return watermark;
}));

在页面中达到如下图效果：