watermark-package/dist/watermark.esm.js

一个非常简单的前端设置水印package

var Watermark = {};

const WaterMarkDomId = 'w_vm_id_3.14159';

// 参数配置
var w_options = {
  // 水印块宽度
  w_width: 240,
  // 水印块高度
  w_height: 140,
  // 水印区域top距离
  w_top: '0px',
  // 水印区域left距离
  w_left: '0px',
  // 旋转角度
  w_rotateDeg: 25,
  // 字体大小、风格
  w_font: '1.2rem Vedana',
  // 字体颜色 rgb | 16进制字符串
  w_color: '#666',
  // 透明度
  w_opacity: '0.1',
  // 层级
  w_zIndex: '100000',
};

// 添加水印
Watermark.setWaterMark = (options) => {
  var id = Watermark.loadWatermark(options);
  if (document.getElementById(id) === null) {
    id = Watermark.loadWatermark(options);
  }
};

// 移除水印
Watermark.removeWatermark = () => {
  var id = WaterMarkDomId;
  if (document.getElementById(id) !== null) {
    Watermark.Observer.disconnect(); // 停止监听
    setTimeout(() => {
      document.body.removeChild(document.getElementById(id));
    }, 0);
  }
};

/**
 * 水印添加方法
 * @param { { w_texts: array, w_options: object } } options 配置对象
 * - w_texts：水印文案字符串数组集合 
 * - w_options：水印参数配置
 * @example
 * options = {
    w_texts: ['娃哈哈', '177****0000'],
    w_options: {
        w_width: 240,
        w_height: 140,
        w_top: '0px',
        w_left: '0px',
        w_rotateDeg: 25,
        w_font: '1.2rem Vedana',
        w_color: '#666',
        w_opacity: '0.2',
        w_zIndex: '100000',
    }
  }
 * @return { string } 返回水印id
 * 
 */
Watermark.loadWatermark = (options) => {
  var _options = {};
  if (options.w_options && Object.prototype.toString.call(options.w_options) === "[object Object]") {
    _options = Object.assign({}, w_options, options.w_options);
  } else {
    _options = w_options;
  }

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

  var can = document.createElement('canvas');
  // 设置canvas画布大小
  can.width = _options.w_width;
  can.height = _options.w_height;

  var cans = can.getContext('2d');
  cans.rotate(-(_options.w_rotateDeg * Math.PI / 180)); // 水印旋转角度
  cans.font = _options.w_font;
  cans.fillStyle = _options.w_color;
  cans.textAlign = 'center';
  cans.textBaseline = 'Middle';

  // 水印在画布的位置x，y轴
  if (options.w_texts && Object.prototype.toString.call(options.w_texts) === "[object Array]") {
    var w_texts = options.w_texts;
    for (var index = 0; index < w_texts.length; index++) {
      cans.fillText(w_texts[index] ? w_texts[index] : '', can.width / 2, can.height + index * 25);
    }
  }

  // 生成水印遮罩
  var div = document.createElement('div');
  div.id = id;
  div.style.pointerEvents = 'none';
  div.style.top = _options.w_top;
  div.style.left = _options.w_left;
  div.style.opacity = _options.w_opacity;
  div.style.position = 'fixed';
  div.style.zIndex = _options.w_zIndex;
  div.style.width = '100%';
  div.style.height = '100%';
  div.style.background = 'url(' + can.toDataURL('image/png') + ') left top repeat';
  document.body.appendChild(div);

  setTimeout(() => {
    // 监听水印防篡改
    Watermark.observeDomChange(div, options);
  }, 0);

  return id
};

/**
 * 基于MutationObserver 监听水印DOM变化
 * @param {*} waterMarkDom 水印DOM
 * @param {*} options 水印参数配置
 */
Watermark.observeDomChange = (waterMarkDom, options) => {

  // 选择需要观察变动的节点
  const targetNode = document.querySelector('body');

  // 观察器的配置（需要观察什么变动）
  const config = {
    attributes: true, // 观察属性变动
    childList: true, // 观察目标子节点的变化，是否有添加或者删除
    subtree: true, // 观察后代节点，默认为 false
  };

  // 当观察到变动时执行的回调函数
  const callback = function (mutationsList, observer) {
    for (let mutation of mutationsList) {

      /** 修改了水印节点属性 */
      if (mutation.target === waterMarkDom) {
        // window.alert('非法操作！！！')
        mutation.target.remove(); // 删除已经修改的水印节点
        Watermark.loadWatermark(options); // 重新渲染水印
        // 停止观察
        observer.disconnect();
      }

      /** 强行手动删除了水印节点 */
      if (mutation.removedNodes.length && mutation.removedNodes[0] === waterMarkDom) {
        // window.alert('非法操作！！！')
        Watermark.loadWatermark(options);
        // 停止观察
        observer.disconnect();
      }
    }
  };

  // 创建一个观察器实例并传入回调函数 
  // 用法详见: https://developer.mozilla.org/zh-CN/docs/Web/API/MutationObserver
  Watermark.Observer = new MutationObserver(callback);

  // 以上述配置开始观察目标节点
  Watermark.Observer.observe(targetNode, config);
};

export { Watermark as default };