let app = getApp();
Page({
 data: {
 img: "/images/1.jpg"
 },
 onLoad() {
 },
 scan() {
 wx.scanCode({
  success: (res) => {
  console.log("扫码结果");
  console.log(res);
  this.setData({
   img: res.result
  })
  },
  fail: (res) => {
  console.log(res);
  }
 })
 }
})

<view class="view">
 <image class="cover-9" src="{{img}}" bindtap="img"></image>
 <button type="primary" bindtap="scan" id="scan">扫一扫</button>
</view>

page{
 height: 100%;
}
.view{
 width: 100%;
 height: 100%;
}
.cover-9{
 width: 688rpx;
 height: 80%;
 margin: 0 30rpx;
 border:2rpx solid;
 border-radius:5px; 
}
button{
 margin: 0 10rpx;
 width: 100%;
}
#scan{
 width: 730rpx;
}