前端水印

//判断时间是否为个位数，如果时间为个位数就在时间之前补上一个“0”
function check(val) {
if (val < 10) {
return (“0” + val);
}
else {
return (val);
}
}
function displayTime() {
//获取div元素
var timeDiv=document.getElementById(“timeDiv”);
//获取系统当前的年、月、日、小时、分钟、毫秒
var date = new Date();
var year = date.getFullYear();
var month = date.getMonth() + 1;
var day = date.getDate();
var hour = date.getHours();
var minutes = date.getMinutes();
var second = date.getSeconds();
var timestr = year + “年” + month + “月” + day + "日 " + check(hour)
+ “:” + check(minutes) + “:” + check(second);
//将系统时间设置到div元素中
return timestr;
}

/**
* 给页面添加文字水印
* @author 海角在眼前
*/
var watermarkUseing;
(function(){

var watermark = function(self){
    this.elem = self;
}

watermark.prototype = {
    defaults : {
        texts : ['此处水印文字'],
        width : 100, //每行水印文字的水平间距
        height : 100, //水印文字的高度间距（低于文字高度会被替代）
        textRotate : -30 , //文字旋转 度数
        textColor : '#e5e5e5', //文字颜色
        textFont : '14px 微软雅黑' //字体
    },
    options : {
        canvas : []
    },
    init : function(options){
         $.extend(this.options, this.defaults, options);
        var $body = $('body'),
            can1 = this.__createCanvas($body),
            can2 = this.__createCanvas($body),
            canAll = this.__createCanvas($body),
            settings = this.options,
            txtlen = settings.texts.length;

        settings.deg = settings.textRotate * Math.PI / 180; //js里的正弦余弦用的是弧度

        this.__calcTextSize($body);
        var repeatTimes = Math.ceil(screen.width / settings.txts.length / settings.width);
        settings.canvasWidth = settings.canvasWidth * repeatTimes;
        var extTxts = [];
        while(repeatTimes--) extTxts = extTxts.concat(settings.txts);
        settings.txts = extTxts;

        var fixH = settings.maxWidth * Math.abs(Math.sin(settings.deg)) + Math.cos(settings.deg) * settings.textHeight;
        if(fixH > settings.height) settings.height = fixH;
        var ctx1 = this.__setCanvasStyle(can1, settings.canvasWidth, settings.height);
        var ctx2 = this.__setCanvasStyle(can2, settings.canvasWidth, settings.height);
        var ctx = this.__setCanvasStyle(canAll, settings.canvasWidth, settings.height * 2, true);

        this.__drawText(ctx1, settings.txts);
        this.__drawText(ctx2, settings.txts.reverse());

        //合并canvas
        ctx.drawImage(can1, 0, 0, settings.canvasWidth, settings.height);
        ctx.drawImage(can2, 0, settings.height, settings.canvasWidth, settings.height);
        var dataURL = canAll.toDataURL("image/png");
        $(this.elem).css('backgroundImage', "url("+ dataURL +")");
        //this.__destory();
    },
    __createCanvas : function($container){
        var canvas = document.createElement('canvas');
        $container.append(canvas);
        this.options.canvas.push(canvas); 
        return canvas;
    },
    __calcTextSize : function($container){
        var txts = [],
            maxWidth = 0,
            canvasWidth = 0,
            settings = this.options;
        $.each(settings.texts, function(i, text){
            var span = $('<span style="font:'+settings.textFont+';visibility: hidden;display: inline-block;"> '+text+ '</span>')
                .appendTo($container);
            var tWidth = span[0].offsetWidth,
                tHeight = span[0].offsetHeight;
            span.remove();
            txts.push({
                txt : text,
                width : tWidth,
                height : tHeight
            });
            maxWidth = Math.max(maxWidth, tWidth);
            settings.textHeight = tHeight;
            var shadow = Math.cos(settings.deg) * tWidth;
            canvasWidth += (settings.width < shadow ? shadow : settings.width) - tHeight * Math.sin(settings.deg);
        });
        settings.txts = txts;
        settings.maxWidth = maxWidth;
        settings.canvasWidth = canvasWidth;
    },
    __setCanvasStyle : function(canvas, width, height, notextstyle){
        canvas.width = width;
        canvas.height = height;
        canvas.style.display='none';
       
        var ctx = canvas.getContext('2d');
        if(!notextstyle){
            var deg = this.options.deg,
                absSindeg = Math.abs(Math.sin(deg));
            ctx.rotate(deg);
            //基于视窗的 x、y偏移量
            var offset = absSindeg * this.options.height - this.options.textHeight * absSindeg;
            var nx = - offset * Math.cos(deg),
                ny = - offset * absSindeg;
            ctx.translate( nx, ny * absSindeg);

            ctx.font = this.options.textFont; 
            ctx.fillStyle = this.options.textColor;
            ctx.textAlign = 'left'; 
            ctx.textBaseline = 'Middle';
        }
        return ctx;
    },
    __drawText: function(ctx, txts){
        var settings = this.options;
        $.each(txts, function(i, obj){
            
            var wnap = (settings.maxWidth - obj.width) / 2 ;
            var x = settings.width * Math.cos(settings.deg) * i,
                y = - x * Math.tan(settings.deg) + settings.height;
            ctx.fillText(obj.txt, x + wnap, y);
        });
    },
    __destory : function(){
        $.each(this.options.canvas, function(i, canvas){
            canvas.remove();
            canvas = null;
        });
    }
}

$.fn.watermark = function(options){
    if (typeof (watermarkUseing) != "undefined") {
        watermarkUseing.__destory();
    }
    watermarkUseing = new watermark(this);
    watermarkUseing.init(options);
}

})(jQuery);

(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:’#FF0000’,//水印字体颜色
watermark_alpha:0.4,//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:0.4 //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;
    var flag=false;
    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
            // if (flag) {
            //     mask_div.style.marginLeft='100px';
            // }
            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

            // flag=!flag;
        };
    };
    //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 = {});