camera组件返回图片宽高由什么决定？

<camera style=“height: 200px; width: 100%;”></camera>

<button bindtap=“takePhoto”>拍照</button>

takePhoto () {

let _this = this;

wx.createCameraContext().takePhoto({

success: function (res) {

console.log(res);

_this.setData({ tempPath: res.tempImagePath });

}

});

},

返回的res中height为116，width为720，height由什么决定？