现有需求，点击全屏，再点退出全屏。

手机端 正常，电脑端无效。

在外层绑定，内层监听。

<view bindtap="onChangeScreen">
   <live-player id="livePlayer" bindfullscreenchange="fullscreenchange"></live-player>    
</view>
//js
data:{
isScreen:false
} 
fullscreenchange(e){
let { fullScreen } = e.detail
this.setData({isScreen:fullScreen })
}
onChangeScreen(){
wx.createSelectorQuery().select("#livePlayer").context((res)=>{
let  context = res.context 
if(isScreen){ context.exitFullScreen() }else{  context.requestFullScreen({direction: 90 }) }
})
}