前端页面添加水印

watermark.js

import watermarkImg from '@/assets/img/watermark.png'
/*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: "测试水印",             //水印的内容
    watermark_img: watermarkImg,        //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: 1,                   //水印列数
    watermark_x_space: 50,              //水印x轴间隔
    watermark_y_space: 300,               //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: 1,               //水印透明度，要求设置在大于等于0.005
    watermark_width: 492,                //水印宽度
    watermark_height: 370,               //水印长度
    watermark_angle: 0,                 //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: 'credit_report',     //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 (const 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*/
        // pointer-events: none !important;
        otdiv.id = defaultSettings.watermark_id;
        otdiv.setAttribute('style', ' display: block !important; width: 900px; margin: 0 auto');
        /*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);
            var oImg = document.createElement("img");
            oImg.src = defaultSettings.watermark_img;
            oImg.style.width = defaultSettings.watermark_width + 'px';
            oImg.style.height = defaultSettings.watermark_height + 'px';

            mask_div.appendChild(oImg);
            /*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 (const 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);
    // :ambulance: remove()
    // minotor 这个配置有些冗余
    // 如果用 MutationObserver 来监听dom变化防止删除水印
    // remove() 方法里用 MutationObserver 的 disconnect() 解除监听即可
    watermarkDom.disconnect();
};

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);
        return;
    }

    // 监听父节点的尺寸是否发生了变化, 如果发生改变, 则进行重新绘制
    var watermark_parent_element = document.getElementById(defaultSettings.watermark_parent_node);
    if (watermark_parent_element) {
        var newWidth = getComputedStyle(watermark_parent_element).getPropertyValue('width');
        var newHeight = getComputedStyle(watermark_parent_element).getPropertyValue('height');
        if (newWidth !== recordOldValue.width || newHeight !== recordOldValue.height) {
            recordOldValue.width = newWidth;
            recordOldValue.height = newHeight;
            loadMark(globalSetting);
        }
    }
};
const MutationObserver = window.MutationObserver || window.WebKitMutationObserver || window.MozMutationObserver;
var watermarkDom = new MutationObserver(callback);
var option = {
    'childList': true,
    'attributes': true,
    'subtree': true,
    'attributeFilter': ['style'],
    'attributeOldValue': true
};
var recordOldValue = {
    width: 0,
    height: 0
}

export default watermark;

vue文件代码中：

this.$nextTick().then(() => {
      watermark.load({});
    })

配置项：watermark_parent_node为水印的父节点