wxml内容：

<view class="container">
  <navigator class="search">
    <icon type="search" size="13"></icon>搜索
  </navigator>

  <view class="banner_box">
    <swiper class="banner" indicator-dots="true" indicator-color="rbag(255,255,255,0.3)" indicator-active-color="#42bd56" autoplay="true"
 circular="true" style="height:{{swiperHeight}}">
      <block wx:for="{{bannerData}}">  //从'indicator-dots'开始分别是设置轮播图的圆点，圆点颜色，轮播到某图时圆点的颜色，自动播放，圆点出现，swiperHeight：图片的高度

          <swiper-item>
            <navigator>
              <image mode="widthFix" src="{{item.banner_img}}" bindload="imgLoad"></image>  //bindload：图片加载后触发的时间 ,这里要设置mode="widthFix"

 

 

            </navigator>
          </swiper-item>
      </block>
    </swiper>
  </view>
</view>

js内容：

//获取应用实例
const app = getApp()

Page({
  data: {
    bannerData: [{ id: 1, banner_img: "https://img3.doubanio.com/view/photo/l/public/p2563815623.webp" }, { id: 2, banner_img: "https://img3.doubanio.com/view/photo/l/public/p2564461744.webp" }, { id: 3, banner_img: "https://img3.doubanio.com/view/photo/s_ratio_poster/public/p2563630521.webp" }
    ],
   
    swiperHeight:0
  },

  
  onl oad: function () {
    
  },

  imgLoad:function(e){
    console.log(e.detail);
    var winWidth=wx.getSystemInfoSync().windowWidth //获取屏幕宽度

    var imgWidth=e.detail.width; //图片宽度
    var imgHeight = e.detail.height; //图片宽度
    this.setData({
      swiperHeight: winWidth*imgHeight/imgWidth+'px'  
    })


  }
})

css内容：

/*搜索*/
.search{
  width: 90vw;
  height: 60rpx;
  line-height: 60rpx;
  text-align: center;
  margin: 30rpx auto;
  background-color: #f7f7f7;
  color: #bbb;
}

.search icon{
  margin-right: 12rpx;
}

.banner navigator{
  width: 100%;
  height: 100%;
}

 .banner image{
   width: 100%;
   height: 100%;
 }

结果：