Overview master分支：手势 gravity分支：摇一摇 try_camera分支：人脸检测 References https://juejin.im/entry/58c66c9a570c35006d6bacf8 https://www.jianshu.com/p/a1df3476c82f https://zhuanlan.zhihu.com/p/46189118?utm_source=wechat_session&utm_medium=social&utm_oi=603232655068762112 https://www.runoob.com/android/android-tutorial.html