web页面和小程序页面实现瀑布流效果
小程序实现瀑布流效果，和web页面差不多，都要经过以下步骤：
1)、加载图片，获取图片的宽高度；
2)、根据页面需要显示几列计算每列的宽度；
3)、根据图片真实宽度和每列的宽度比，计算出图片需要显示的高度；
4)、重新对图片进行定位
1、web页面瀑布流效果，先看效果图（瀑布流+无限滚动加载）：
页面代码：
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta charset=’utf-8′> <!--声明文档使用的字符编码--> <title>瀑布流_左浮动</title> <style type="text/css"> *{margin:0;padding:0;} .container { width: 1200px; height: auto; margin: 50px auto; position: relative; } .box{ padding: 5px; box-shadow: 0 0 10px purple; border-radius: 5px; float: left; margin: 10px; } .box img { width: 200px; height: auto; } </style> </head> <body> <div class="container"> <div class="box"><img src="../img/0.jpg"/></div> <div class="box"><img src="../img/1.jpg"/></div> <div class="box"><img src="../img/2.jpg"/></div> <div class="box"><img src="../img/3.jpg"/></div> <div class="box"><img src="../img/4.jpg"/></div> <div class="box"><img src="../img/5.jpg"/></div> <div class="box"><img src="../img/6.jpg"/></div> <div class="box"><img src="../img/7.jpg"/></div> <div class="box"><img src="../img/8.jpg"/></div> <div class="box"><img src="../img/9.jpg"/></div> <div class="box"><img src="../img/10.jpg"/></div> <div class="box"><img src="../img/11.jpg"/></div> <div class="box"><img src="../img/12.jpg"/></div> <div class="box"><img src="../img/13.jpg"/></div> <div class="box"><img src="../img/14.jpg"/></div> <div class="box"><img src="../img/15.jpg"/></div> <div class="box"><img src="../img/16.jpg"/></div> </div> <script type="text/javascript"> var boxsHeight = []; //盒子高度存储数组 var boxWidth = 230, boxHeight = 230; window.onload = function(){ var boxs = document.getElementsByClassName('box'); var cols = Math.floor(1200.0/boxWidth); //最多几列 //offsetWidth: 包括元素的内容宽度+padding+border宽度 //存储第一行的每个盒子的高度到数组里面 for (var i = 0; i < cols; i++){ var obj = boxs[i]; //元素节点 if (i < cols){ boxsHeight.push(obj.offsetHeight); } } updateBoxFrame(cols); //从第二行开始更新元素的位置 window.onscroll = pageScroll; //设置页面滚动监听函数 pageScroll(); //先调用一次 } //获取数组中最小值的索引 function getMinHeightIndex(arr){ var minHeight = Math.min.apply(null, arr); for (var i = 0; i < arr.length; i++){ if (arr[i] == minHeight){ return i; } } } //监听页面滚动 function pageScroll(){ var parentEle = document.getElementsByClassName('container')[0]; var subEleCount = parentEle.childElementCount; //子元素个数 var lastBox = parentEle.lastElementChild; //最后一个元素 //判断是否滚动到底部 var doc = document.documentElement||document.body; console.log('滚动监听', doc.scrollTop+",", lastBox.offsetTop+", " + doc.clientHeight); if (doc.scrollTop+doc.clientHeight > lastBox.offsetTop){ //表示该新添加元素了 addBox(); //更新新添加元素的位置 updateBoxFrame(subEleCount); } } //新添加子元素 function addBox(){ var parentEle = document.getElementsByClassName('container')[0]; var arr = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16]; for (var i = 0; i < arr.length; i++){ var index = parseInt(Math.random()*100%arr.length); var imgNum = arr[index]; var div = document.createElement('div'); div.setAttribute('class', 'box'); div.innerHTML = '<img src="../img/' + imgNum + '.jpg"/>' parentEle.appendChild(div); arr.splice(index, 1) } } //更新新添加元素的位置 function updateBoxFrame(startIndex){ var boxs = document.getElementsByClassName('box'); for (var i = startIndex; i < boxs.length; i++){ var obj = boxs[i]; //获取数组中最小高度的索引 var minHeightIndex = getMinHeightIndex(boxsHeight); // console.log(boxsHeight); // console.log(minHeightIndex + ", " +boxsHeight[minHeightIndex]); var boxTop = boxsHeight[minHeightIndex] + 20; var boxLeft = minHeightIndex * boxWidth; console.log(i + ', boxTop: ' + boxTop + ", boxLeft: " + boxLeft); //设置元素的定位样式 obj.style = 'position: absolute; top:' + boxTop + "px;left:" + boxLeft+"px"; boxsHeight[minHeightIndex] = boxTop + obj.offsetHeight; } } </script> </body> </html>
2、小程序实现瀑布流，大致流程差不多。只不过小程序的图片的宽高度的获取没有web页面那么方便。
大概实现过程：1）、获取图片数据，页面渲染；
2）、给图片绑定加载load事件，存储每个图片的宽高度；
3）、计算每个图片的定位，重新渲染
先看小程序的效果图（瀑布流+无限循环加载）：
wxml页面代码：
<scroll-view class='main' scroll-y='true' style="height:{{windowHeight}}px" bindscrolltolower='loadMoreImages'> <image wx:for='{{dataList}}' wx:key='item' src='{{item.src}}' style='position: absolute; top: {{item.top}}px; left: {{item.left}}px; width: {{imgWidth}}px; height: {{item.height}}px' bindload='loadImage' data-index='{{index}}' bindtap='previewImg'/> </scroll-view>
js页面代码：
// pages/discover/waterfall_flow/waterfall_flow.js Page({ /** * 页面的初始数据 */ data: { dataList: [], //数据源 windowWidth: 0, //页面视图宽度 windowHeight: 0, //视图高度 imgMargin: 6, //图片边距: 单位px imgWidth: 0, //图片宽度: 单位px topArr: [0, 0], //存储每列的累积top }, /** * 生命周期函数--监听页面加载 */ onLoad: function (options) { wx.showLoading({ title: '加载中...', }) var that = this; //获取页面宽高度 wx.getSystemInfo({ success: function (res) { console.log(res) var windowWidth = res.windowWidth; var imgMargin = that.data.imgMargin; //两列，每列的图片宽度 var imgWidth = (windowWidth - imgMargin * 3) / 2; that.setData({ windowWidth: windowWidth, windowHeight: res.windowHeight, imgWidth: imgWidth }, function () { that.loadMoreImages(); //初始化数据 }); }, }) }, //加载图片 loadImage: function (e) { var index = e.currentTarget.dataset.index; //图片所在索引 var imgW = e.detail.width, imgH = e.detail.height; //图片实际宽度和高度 var imgWidth = this.data.imgWidth; //图片宽度 var imgScaleH = imgWidth / imgW * imgH; //计算图片应该显示的高度 var dataList = this.data.dataList; var margin = this.data.imgMargin; //图片间距 //第一列的累积top，和第二列的累积top var firtColH = this.data.topArr[0], secondColH = this.data.topArr[1]; var obj = dataList[index]; obj.height = imgScaleH; if (firtColH < secondColH) { //表示新图片应该放到第一列 obj.left = margin; obj.top = firtColH + margin; firtColH += margin + obj.height; } else { //放到第二列 obj.left = margin * 2 + imgWidth; obj.top = secondColH + margin; secondColH += margin + obj.height; } this.setData({ dataList: dataList, topArr: [firtColH, secondColH], }); }, //加载更多图片 loadMoreImages: function () { var imgs = [ 'https://ss1.bdstatic.com/70cFuXSh_Q1YnxGkpoWK1HF6hhy/it/u=1409185525,4059560780&fm=26&gp=0.jpg', 'https://ss3.bdstatic.com/70cFv8Sh_Q1YnxGkpoWK1HF6hhy/it/u=4076355782,2436939971&fm=15&gp=0.jpg', 'https://ss1.bdstatic.com/70cFuXSh_Q1YnxGkpoWK1HF6hhy/it/u=777075993,2126273204&fm=11&gp=0.jpg', 'https://ss2.bdstatic.com/70cFvnSh_Q1YnxGkpoWK1HF6hhy/it/u=57777155,3251523579&fm=11&gp=0.jpg', 'https://ss3.bdstatic.com/70cFv8Sh_Q1YnxGkpoWK1HF6hhy/it/u=3825727093,2830650732&fm=11&gp=0.jpg', 'https://ss2.bdstatic.com/70cFvnSh_Q1YnxGkpoWK1HF6hhy/it/u=2379065095,654347953&fm=26&gp=0.jpg', 'https://ss1.bdstatic.com/70cFuXSh_Q1YnxGkpoWK1HF6hhy/it/u=2749679283,2472217536&fm=11&gp=0.jpg', 'https://ss3.bdstatic.com/70cFv8Sh_Q1YnxGkpoWK1HF6hhy/it/u=677128138,409184861&fm=11&gp=0.jpg', 'https://ss0.bdstatic.com/70cFvHSh_Q1YnxGkpoWK1HF6hhy/it/u=1884091074,3049103326&fm=26&gp=0.jpg', 'https://ss1.bdstatic.com/70cFuXSh_Q1YnxGkpoWK1HF6hhy/it/u=1600363417,3661952978&fm=11&gp=0.jpg', 'https://ss2.bdstatic.com/70cFvnSh_Q1YnxGkpoWK1HF6hhy/it/u=2069544162,3090555174&fm=11&gp=0.jpg', 'https://ss0.bdstatic.com/70cFuHSh_Q1YnxGkpoWK1HF6hhy/it/u=3328655038,3143543956&fm=26&gp=0.jpg', 'https://ss1.bdstatic.com/70cFvXSh_Q1YnxGkpoWK1HF6hhy/it/u=3953624046,2332872335&fm=26&gp=0.jpg', 'https://ss0.bdstatic.com/70cFuHSh_Q1YnxGkpoWK1HF6hhy/it/u=717009955,687560133&fm=26&gp=0.jpg', 'https://ss1.bdstatic.com/70cFvXSh_Q1YnxGkpoWK1HF6hhy/it/u=4243037288,2388509769&fm=26&gp=0.jpg', 'https://ss0.bdstatic.com/70cFuHSh_Q1YnxGkpoWK1HF6hhy/it/u=2644451528,4180971732&fm=26&gp=0.jpg', 'https://ss0.bdstatic.com/70cFuHSh_Q1YnxGkpoWK1HF6hhy/it/u=2658655215,924706045&fm=26&gp=0.jpg', 'https://ss1.bdstatic.com/70cFvXSh_Q1YnxGkpoWK1HF6hhy/it/u=400545645,1325440240&fm=26&gp=0.jpg', 'https://ss0.bdstatic.com/70cFvHSh_Q1YnxGkpoWK1HF6hhy/it/u=2735743532,3162562682&fm=11&gp=0.jpg', 'https://ss1.bdstatic.com/70cFvXSh_Q1YnxGkpoWK1HF6hhy/it/u=2357555025,1781222560&fm=26&gp=0.jpg', 'https://ss1.bdstatic.com/70cFvXSh_Q1YnxGkpoWK1HF6hhy/it/u=1604156508,3282489713&fm=26&gp=0.jpg', 'https://ss1.bdstatic.com/70cFuXSh_Q1YnxGkpoWK1HF6hhy/it/u=380663325,2271064034&fm=26&gp=0.jpg', 'https://ss0.bdstatic.com/70cFvHSh_Q1YnxGkpoWK1HF6hhy/it/u=174537541,3462862985&fm=26&gp=0.jpg', 'https://ss0.bdstatic.com/70cFuHSh_Q1YnxGkpoWK1HF6hhy/it/u=1752649241,364583051&fm=26&gp=0.jpg', 'https://ss1.bdstatic.com/70cFuXSh_Q1YnxGkpoWK1HF6hhy/it/u=2890516059,4166188770&fm=27&gp=0.jpg', 'https://ss2.bdstatic.com/70cFvnSh_Q1YnxGkpoWK1HF6hhy/it/u=2435144503,200941795&fm=11&gp=0.jpg', 'https://ss0.bdstatic.com/70cFvHSh_Q1YnxGkpoWK1HF6hhy/it/u=877833827,2847590581&fm=26&gp=0.jpg', 'https://ss3.bdstatic.com/70cFv8Sh_Q1YnxGkpoWK1HF6hhy/it/u=894452177,2810600152&fm=11&gp=0.jpg', 'https://ss2.bdstatic.com/70cFvnSh_Q1YnxGkpoWK1HF6hhy/it/u=4053642431,248486335&fm=27&gp=0.jpg', 'https://ss1.bdstatic.com/70cFvXSh_Q1YnxGkpoWK1HF6hhy/it/u=2914607659,905736210&fm=11&gp=0.jpg', 'https://ss1.bdstatic.com/70cFvXSh_Q1YnxGkpoWK1HF6hhy/it/u=1629456501,1514429218&fm=26&gp=0.jpg', ]; var tmpArr = []; for (let i = 0; i < 22; i++) { var index = parseInt(Math.random() * 100) % imgs.length; var obj = { src: imgs[index], height: 0, top: 0, left: 0, } tmpArr.push(obj); imgs.splice(index, 1); } var dataList = this.data.dataList.concat(tmpArr) this.setData({ dataList: dataList }, function(){ wx.hideLoading() }); }, /**预览图片 */ previewImg: function (e) { var index = e.currentTarget.dataset.index; var dataList = this.data.dataList; var currentSrc = dataList[index].src; // var srcArr = dataList.map(function (item) { // return item.src; // }); wx.previewImage({ urls: [currentSrc], }) }, })
wxss页面代码：
.main{ width: 100%; height: 100%; position: relative; } .main image { box-shadow: 0 0 10rpx red; border-radius: 8rpx; }
DEMO下载：https://github.com/xiaotanit/Tan_HtmlDemo
web瀑布流页面地址：https://github.com/xiaotanit/Tan_HtmlDemo/blob/master/JS/%E7%80%91%E5%B8%83%E6%B5%81_%E5%B7%A6%E6%B5%AE%E5%8A%A8.html
小程序瀑布流页面地址：https://github.com/xiaotanit/Tan_HtmlDemo/tree/master/wxMini/pages/discover/waterfall_flow
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