JS 添加背景水印（适用于 PC 端和移动端）

清疚 2022-12-14 06:20 260阅读 0赞

## 前言 ##

因为这个看网上已经有很多的案例了，所以我就简单的记录一下，方式都是大差不差的。

## 正文 ##

JS 调用示例，参数配置可自己调节，适用于移动端和PC端

调用方法：watermark({ watermark_txt: "测试水印" })
    
    function watermark(settings) {
            //默认设置
            var defaultSettings={
                watermark_txt:"text",
                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:20,//水印行数
                watermark_cols:20,//水印列数
                watermark_x_space:10,//水印x轴间隔
                watermark_y_space:30,//水印y轴间隔
                watermark_color:'#aaa',//水印字体颜色
                watermark_alpha:0.4,//水印透明度
                watermark_fontsize:'15px',//水印字体大小
                watermark_font:'微软雅黑',//水印字体
                watermark_width:160,//水印宽度
                watermark_height:160,//水印长度
                watermark_angle:15//水印倾斜度数
            };
            //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;
                    else if(src[key])
                        defaultSettings[key]=src[key];
                }
            }
    
            var oTemp = document.createDocumentFragment();
    
            //获取页面最大宽度
            var page_width = Math.max(document.body.scrollWidth,document.body.clientWidth);
            var cutWidth = page_width*0.0150;
            var page_width=page_width-cutWidth;
            //获取页面最大高度
            var page_height = Math.max(document.body.scrollHeight,document.body.clientHeight)+450;
            // var page_height = document.body.scrollHeight+document.body.scrollTop;
            //如果将水印列数设置为0，或水印列数设置过大，超过页面最大宽度，则重新计算水印列数和水印x轴间隔
            if (defaultSettings.watermark_cols == 0 || (parseInt(defaultSettings.watermark_x + defaultSettings.watermark_width *defaultSettings.watermark_cols + defaultSettings.watermark_x_space * (defaultSettings.watermark_cols - 1)) > page_width)) {
                defaultSettings.watermark_cols = parseInt((page_width-defaultSettings.watermark_x+defaultSettings.watermark_x_space) / (defaultSettings.watermark_width + defaultSettings.watermark_x_space));
                defaultSettings.watermark_x_space = parseInt((page_width - defaultSettings.watermark_x - defaultSettings.watermark_width * defaultSettings.watermark_cols) / (defaultSettings.watermark_cols - 1));
            }
            //如果将水印行数设置为0，或水印行数设置过大，超过页面最大长度，则重新计算水印行数和水印y轴间隔
            if (defaultSettings.watermark_rows == 0 || (parseInt(defaultSettings.watermark_y + defaultSettings.watermark_height * defaultSettings.watermark_rows + defaultSettings.watermark_y_space * (defaultSettings.watermark_rows - 1)) > page_height)) {
                defaultSettings.watermark_rows = parseInt((defaultSettings.watermark_y_space + page_height - defaultSettings.watermark_y) / (defaultSettings.watermark_height + defaultSettings.watermark_y_space));
                defaultSettings.watermark_y_space = parseInt(((page_height - defaultSettings.watermark_y) - defaultSettings.watermark_height * defaultSettings.watermark_rows) / (defaultSettings.watermark_rows - 1));
            }
            var x;
            var y;
            for (var i = 0; i < defaultSettings.watermark_rows; i++) {
                y = defaultSettings.watermark_y + (defaultSettings.watermark_y_space + defaultSettings.watermark_height) * i;
                for (var j = 0; j < defaultSettings.watermark_cols; j++) {
                    x = defaultSettings.watermark_x + (defaultSettings.watermark_width + defaultSettings.watermark_x_space) * j;
    
                    var mask_div = document.createElement('div');
                    mask_div.id = 'mask_div' + i + j;
                    mask_div.className = 'mask_div';
                    mask_div.appendChild(document.createTextNode(defaultSettings.watermark_txt));
                    //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";
                    mask_div.style.left = x + 'px';
                    mask_div.style.top = y + 'px';
                    mask_div.style.overflow = "hidden";
                    mask_div.style.zIndex = "9999";
                    mask_div.style.pointerEvents='none';//pointer-events:none  让水印不遮挡页面的点击事件
                    //mask_div.style.border="solid #eee 1px";
                    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";
                    oTemp.appendChild(mask_div);
                };
            };
            document.body.appendChild(oTemp);
        }