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：
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<!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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