1.需求
想做类似猫眼电影选场次会自动滚动到屏幕中间的效果
如图是最终效果
2.分析
实现这种效果的方法有三种：
1.直接使用原生CSS+js;
2.使用swiper,一屏显示多个item,点击item会自动滚动到中间
3.使用微信的scroll-view配合JS实现
权衡了一下最终选择了第三个方案，比较是微信自带的方法，使用起来会比较流畅，swiper的话会比较臃肿，原生的话就比较麻烦，需要考虑的兼容问题比较多。
3.代码
wxml
<view class="items-box">
<scroll-view class="scroll-view_H" scroll-x="true" style="width: 100%" bindscroll="scrollMove" scroll-left='{{scrollLeft}}' scroll-with-animation="true">
<view class="scroll-wrapper">
<view id="scroll-item-{{index}}" class="item-pic {{selectItemIndex==index?'on':''}}" wx:for="{{ticketDetails}}" wx:key="index" bindtap="selectItem" data-index="{{index}}" data-name="{{item.TicketTitle}}" data-ticketid='{{item.TicketId}}'>
<image src='{{imgUrl}}{{item.TicketPostImg}}'></image>
</view>
</view>
</scroll-view>
</view>
<view class="item-name" hidden="{{!selectItemName}}">{{selectItemName}}</view>
wxss
.items-box .item-pic image {
width: 90rpx;
height: 120rpx;
}
.items-box .item-pic.on image {
width: 110rpx;
height: 148rpx;
border: 4rpx solid #2bb7b3;
box-sizing: border-box;
}
.items-box .item-pic {
margin: 0 20rpx;
}
.items-box .item-pic:first-child{
padding-left: 300rpx
}
.items-box .item-pic:last-child{
padding-right: 300rpx
}
.item-name {
padding: 18rpx 0;
background-color: #fff;
font-size: 24rpx;
font-weight: 500;
color: #232324;
text-align: center;
}
.items-box .scroll-wrapper {
align-items: flex-end;
padding: 32rpx 0 0 0;
}
.items-box .scroll-view_H {
border: none;
background-color: #edeff1;
}
js
data:{
moveParams: {
scrollLeft: 0
}
}
getRect(ele) {
//获取点击元素的信息,ele为传入的id
var that = this;
//节点查询
wx.createSelectorQuery().select(ele).boundingClientRect(function (rect) {
console.log(rect)
let moveParams = that.data.moveParams;
moveParams.subLeft = rect.left;
moveParams.subHalfWidth = rect.width / 2;
that.moveTo();
}).exec()
},
moveTo: function () {
let subLeft = this.data.moveParams.subLeft;
let screenHalfWidth = this.data.moveParams.screenHalfWidth;
let subHalfWidth = this.data.moveParams.subHalfWidth;
let scrollLeft = this.data.moveParams.scrollLeft;
let distance = subLeft - screenHalfWidth + subHalfWidth;
scrollLeft = scrollLeft + distance;
this.setData({
scrollLeft: scrollLeft
})
},
scrollMove(e) {
let moveParams = this.data.moveParams;
moveParams.scrollLeft = e.detail.scrollLeft;
this.setData({
moveParams: moveParams
})
},
//选择项目
selectItem: function (e) {
let ele = 'scroll-item-' + e.currentTarget.dataset.index
this.getRect('#' + ele);
},
首先获取屏幕的宽度，再获取点击元素的宽度，计算一下就可以获得应该滚动的距离，再更改scroll-left='{{scrollLeft}}'即可
微信获取元素宽高的方法
wx.createSelectorQuery().select(ele).boundingClientRect(function (rect) {
}).exec()
https://developers.weixin.qq.com/miniprogram/dev/api/wxml/wx.createSelectorQuery.html
