camera不显示的问题，但camera的同级却可以正常显示

// wxml
 <camera device-position='front' flash='off' binderror='error' class='camera' hidden='{{ isTakePhoto }}'>
            <cover-image class='camera-img' src='/images/pic_face_area.png'></cover-image>
  </camera>

//app.json
"window": {
        "navigationBarBackgroundColor": "#ffffff",
        "navigationBarTextStyle": "black",
        "navigationBarTitleText": "",
        "backgroundColor": "#f7f7f7",
        "backgroundTextStyle": "dark",
        "navigationStyle": "default",
        "renderingMode": "seperated"
    },

解决的办法是在app.json中的window对象添加如下字段即可

 "renderingMode": "seperated"