Full Stack Lead  •  Cafe Maidjiku

2016 – 2017 | Hong Kong

• Developed and maintained a complete order system for the cafe. Staff would use Android app to
  • manage customer entry/leaving time
  • make/cancel order
  • scan customer's loyalty card via NFC
• A kiosk developed in C#/WinUI is also available for staff in case of phone unavailability

Android Lead  •  Dreamware

2017 – 2018 | Hong Kong

• Maintained an existing Android app suite, "ischool", tailored for administrative tasks for staff and parents in small-to-mid-scale learning centers for kids
  • Promoted security best practice
  • Adopted 3-layer approach, bridging an originally messy codebase

Android Developer  •  Oursky

2018 – 2019  | Hong Kong

Tech Lead  •  Oursky

2019 – 2024  | Hong Kong/Taipei, Taiwan

Android Native Work in Oursky

• HL Insurance (2019) - Android Lead.
  • https://play.google.com/store/apps/details?id=com.hlinsurance&hl=en-GB
    
  • Tech used: LiveData, ViewMoel, Retrofit, dropped RxJava/Redux
  • Promoted theme, accessibility, responsive layout
    
  • Aligned android design best practice with designer (who is most familiar with iOS), e.g. left-aligned title
  • Shipped order flow with complicated steps for various insurance products that always remember states
    • In case of configuration change (e.g. rotating phone, changing language, changing display density)
    • In case of getting killed by system (save state via Bundle)
  • PII (Personally Identifiable Information) auditing/handling in the whole app
    
  • Misc: Custom View (fancy title animation), Biometrics integration, Sentry integration, Deep Link support
• Kinofi, Camera Mounting Hardware Companion App (2019) - Tech Lead
  • Tech used: Kotlin, Coroutine, Bluetooth LE, LiveData, ViewModel, LifecycleOwner
  • Extremely improved sprint velocity. PM estimated 3 developers (iOS), managed with only 2 (with extra features!)
  • Implemented reliable virtual Bluetooth LE (Low Energy) connection and pairing for Hardware API
  • Hardware API implemented as a separate module for separation of concern
    • Provided a separate app that tests only camera Hardware API for PM/QA
    • Hardware API comes with full Intent-based simulation for adb testing without the actual hardware
  • Implemented Android Camera2 API. Implemented custom camera lifecycle owner for 1-line, bug-free camera acquiring and releasing in Fragments
    • No deadlock, no black screen, no acquiring camera even when the app is closed/off-screen
      
  • Integrated OpenCV in C++ for panorama (photo-stitching)
  • Implemented a face-tracking-provider-agnostic tracker that allowed testing with different ML provider rapidly during development. Eventually integrated FirebaseML
  • Counter-proposed UX improvement to PM: foreground notification for when the hardware is connected (Android specific extra feature)
  • Misc: Sentry, Deep Link
• Movit, Fitness Mirror Launcher App (2021) - Tech Lead
  • Fitness Mirror which was showcased and soft-launched/tested in various hotels
    • Lead PoC and the final product. PoC includes a prototype of motion tracking capability (outsourced eventually) 
  • Tech used: Kotlin, Coroutine, Bluetooth LE, Intent/IntentFilter, 
  • Specified and implemented a protocol for React Native mobile app <-> Mirror Launcher app <-> Game/Sport apps
  • Implemented BLE peripheral and discovery. Implemented mock game/sports apps for easier QA/PM testing
  • Implemented leaderboard and easy sharing via QR code
    
  • Lead React Native mobile app + C#/.NET backend + React SPA CMS
• Authgear Android SDK (2022) - Tech Lead
  • https://github.com/authgear/authgear-sdk-android/
    
  • Developed Android SDK for Authgear, an open-source SaaS product for authentication (SSO, CMS)
  • Spot TOCTTOU bugs in reference implementation (iOS), helped propagating fixes in all SDKs
  • Also developed SDK for Xamarin/MAUI (C#)
• FormX Android SDK (2024) - Maintainer
  • Tech used: Kotlin, Coroutine, LiveData, Firebase ML 
  • Integrated OpenCV in C++ for stitching. Fixed performance issues in existing C++ code

Other Work in Oursky

• React Native (mobile + desktop)
  • Shipped/Maintained 5+ apps
  • Tech used: Functional component, context, react query, custom hooks as state
  • Early adopter of React Native for Windows/macOS. Collaborated with Microsoft engineer
• Flutter (mobile)
  • Shipped/Maintained 3+ apps
  • Tech used: Provider, InAppWebView, State management (without libraries), writing custom flutter plugins/native bridge, custom canvas rendering
• WinUI (windows/browser)
  • Shipped 3 WinUI/Uno based apps. One deployed as WASM application
  • Tech used: UWP/WinUI 2, MVVM, C++/WinRT, full trust (desktop bridge), Appinstaller, Windows Community Toolkit (WCT)

Side Projects

• WinUI, C++/WinRT open source contribution
  • Bug report on WinUI 2/3 (https://github.com/microsoft/microsoft-ui-xaml/issues?q=is%3Aissue%20state%3Aopen%20author%3Aroxk)
  • Microsoft WIL contribution (https://github.com/microsoft/wil/pull/440)
  • SwipeNavigator for UWP (https://github.com/roxk/swipenavigator)
  • idlgen (https://github.com/roxk/idlgen)
• WinReddiT - WinUI 2 UWP reddit client app
  • Personal use only now due to recent reddit API pricing change (plan to publish on Microsoft Store dropped)
  • Can invite to github repository if interested on a case-by-case basis