<!DOCTYPE html>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>瀑布流布局测试</title>
    <style>
        body {
            background-color: #eee;
            font-size: 84%;
            text-align: justify;
        }
        .column {
            display: inline-block;
            vertical-align: top;
        }
        .pic_a {
            display: block;
            padding: 5px;
            margin-bottom: 10px;
            border: 1px solid #ccc;
            background-color: #fff;
            text-decoration: none;
        }
        .pic_a img {
            display: block;
            margin: 0 auto 5px;
            border: 0;
            vertical-align: bottom;
        }
        .pic_a strong {
            color: #333;
        }
    </style>
</head>
<body>
<div id="container"></div>
<script>
    var waterFall = {
        container: document.getElementById("container"),
        columnNumber: 1,
        columnWidth: 210,
        // P_001.jpg ~ P_160.jpg
        rootImage: "http://cued.xunlei.com/demos/publ/img/",
        indexImage: 0,
        scrollTop: document.documentElement.scrollTop || document.body.scrollTop,
        detectLeft: 0,
        loadFinish: false,
        // 返回固定格式的图片名
        getIndex: function() {
            var index = this.indexImage;
            if (index < 10) {
                index = "00" + index;
            } else if (index < 100) {
                index = "0" + index;
            }
            return index;
        },
        // 是否滚动载入的检测
        appendDetect: function() {
            var start = 0;
            for (start; start < this.columnNumber; start++) {
                var eleColumn = document.getElementById("waterFallColumn_" + start);
                if (eleColumn && !this.loadFinish) {
                    if (eleColumn.offsetTop + eleColumn.clientHeight < this.scrollTop + (window.innerHeight || document.documentElement.clientHeight)) {
                        this.append(eleColumn);
                    }
                }
            }
            return this;
        },
        // 滚动载入
        append: function(column) {
            this.indexImage += 1;
            var html = '', index = this.getIndex(), imgUrl = this.rootImage + "P_" + index + ".jpg";
            // 图片尺寸
            var aEle = document.createElement("a");
            aEle.href = "###";
            aEle.className = "pic_a";
            aEle.innerHTML = '<img src="'+ imgUrl +'" /><strong>'+ index +'</strong>';
            column.appendChild(aEle);
            if (index >= 160) {
                //alert("图片加载光光了!");
                this.loadFinish = true;
            }
            return this;
        },
        // 页面加载初始创建
        create: function() {
            this.columnNumber = Math.floor(document.body.clientWidth / this.columnWidth);
            var start = 0, htmlColumn = '', self = this;
            for (start; start < this.columnNumber; start+=1) {
                htmlColumn = htmlColumn + '<span id="waterFallColumn_'+ start +'" class="column" style="width:'+ this.columnWidth +'px;">'+
                    function() {
                        var html = '', i = 0;
                        for (i=0; i<5; i+=1) {
                            self.indexImage = start + self.columnNumber * i;
                            var index = self.getIndex();
                            html = html + '<a href="###" class="pic_a"><img src="'+ self.rootImage + "P_" + index +'.jpg" /><strong>'+ index +'</strong></a>';
                        }
                        return html;
                    }() +
                    '</span> ';
            }
            htmlColumn += '<span id="waterFallDetect" class="column" style="width:'+ this.columnWidth +'px;"></span>';
            this.container.innerHTML = htmlColumn;
            this.detectLeft = document.getElementById("waterFallDetect").offsetLeft;
            return this;
        },
        refresh: function() {
            var arrHtml = [], arrTemp = [], htmlAll = '', start = 0, maxLength = 0;
            for (start; start < this.columnNumber; start+=1) {
                var arrColumn = document.getElementById("waterFallColumn_" + start).innerHTML.match(/<a(?:.|\n|\r|\s)*?a>/gi);
                if (arrColumn) {
                    maxLength = Math.max(maxLength, arrColumn.length);
                    // arrTemp是一个二维数组
                    arrTemp.push(arrColumn);
                }
            }
            // 需要重新排序
            var lengthStart, arrStart;
            for (lengthStart = 0; lengthStart<maxLength; lengthStart++) {
                for (arrStart = 0; arrStart<this.columnNumber; arrStart++) {
                    if (arrTemp[arrStart][lengthStart]) {
                        arrHtml.push(arrTemp[arrStart][lengthStart]);
                    }
                }
            }
            if (arrHtml && arrHtml.length !== 0) {
                // 新栏个数
                this.columnNumber = Math.floor(document.body.clientWidth / this.columnWidth);
                // 计算每列的行数
                // 向下取整
                var line = Math.floor(arrHtml.length / this.columnNumber);
                // 重新组装HTML
                var newStart = 0, htmlColumn = '', self = this;
                for (newStart; newStart < this.columnNumber; newStart+=1) {
                    htmlColumn = htmlColumn + '<span id="waterFallColumn_'+ newStart +'" class="column" style="width:'+ this.columnWidth +'px;">'+
                        function() {
                            var html = '', i = 0;
                            for (i=0; i<line; i+=1) {
                                html += arrHtml[newStart + self.columnNumber * i];
                            }
                            // 是否补足余数
                            html = html + (arrHtml[newStart + self.columnNumber * line] || '');
                            return html;
                        }() +
                        '</span> ';
                }
                htmlColumn += '<span id="waterFallDetect" class="column" style="width:'+ this.columnWidth +'px;"></span>';
                this.container.innerHTML = htmlColumn;
                this.detectLeft = document.getElementById("waterFallDetect").offsetLeft;
                // 检测
                this.appendDetect();
            }
            return this;
        },
        // 滚动加载
        scroll: function() {
            var self = this;
            window.onscroll = function() {
                // 为提高性能,滚动前后距离大于100像素再处理
                var scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
                if (!this.loadFinish && Math.abs(scrollTop - self.scrollTop) > 100) {
                    self.scrollTop = scrollTop;
                    self.appendDetect();
                }
            };
            return this;
        },
        // 浏览器窗口大小变换
        resize: function() {
            var self = this;
            window.onresize = function() {
                var eleDetect = document.getElementById("waterFallDetect"), detectLeft = eleDetect && eleDetect.offsetLeft;
                if (detectLeft && Math.abs(detectLeft - self.detectLeft) > 50) {
                    // 检测标签偏移异常,认为布局要改变
                    self.refresh();
                }
            };
            return this;
        },
        init: function() {
            if (this.container) {
                this.create().scroll().resize();
            }
        }
    };
    waterFall.init();
</script>
</body>
</html>