介绍一个水印插件watermark（不遮挡底部元素）

下面web建站小编给大家简单介绍一个水印插件watermark，这个插件不遮挡底部元素，下面是实现代码！

实现代码如下：

watermark.load({ watermark_txt: "我是水印，watermark水印插件！" });

watermark代码插件代码

(function(watermark){
  window.watermarkdivs = [];
  // 加载水印
  var loadMark = function(settings) {
  	  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:0,//水印行数
  	  	watermark_cols:0,//水印列数
  	  	watermark_x_space:100,//水印x轴间隔
  	  	watermark_y_space:50,//水印y轴间隔
  	  	watermark_color:'#000000',//水印字体颜色
  	  	watermark_alpha:0.5,//水印透明度，要求设置在大于等于0.005
  	  	watermark_fontsize:'18px',//水印字体大小
  	  	watermark_font:'微软雅黑',//水印字体
  	  	watermark_width:150,//水印宽度
  	  	watermark_height:100,//水印长度
  	  	watermark_angle:15,//水印倾斜度数
  	  	watermark_bg_alpha:0.5 //加透明度导致隐形水印无法读取
  	  };
  	  //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];
  	  	}
  	  }
	  
  	  if (window.watermarkdivs && window.watermarkdivs.length > 0) {
  	  	document.body.removeChild(document.getElementById("otdivid"));
  	  	window.watermarkdivs = [];
  	  }
	  
  	  //获取页面最大宽度
  	  var page_width = Math.max(document.body.scrollWidth,document.body.clientWidth);
  	  //获取页面最大长度
  	  var page_height = Math.max(document.body.scrollHeight,document.body.clientHeight);
	  
      // 创建文档碎片
      var oTemp = document.createDocumentFragment();
        //创建水印外壳div
  	  var otdiv = document.getElementById("otdivid");
  	  if(!otdiv){
  	  	otdiv =document.createElement('div');
  	  	otdiv.id="otdivid";
            otdiv.style.pointerEvents = "none";
  	  	document.body.appendChild(otdiv);
  	  }
	  
  	  //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');
  	  	  var oText=document.createTextNode(defaultSettings.watermark_txt);
  	  	  mask_div.appendChild(oText);
          // 设置一张水印相关属性start
          mask_div.id = 'mask_div' + 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 = "9999";
  	  	  //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";
          //设置一张水印相关属性end
          //附加到文档碎片中
          otdiv.appendChild(mask_div);
	  
          window.watermarkdivs.push(otdiv); //控制页面大小变化时水印字体
  	  	};
  	  };
  	  //一次性添加到document中
  	  document.body.appendChild(oTemp);
  	};
  
  watermark.load = function(settings) {
  	window.onload = function() {
  		loadMark(settings);
  	};
  	window.onresize = function() {
  		loadMark(settings);
  	};
  };
	
})(window.watermark = {});