Google Wear OS, formerly Android Wear, is the platform for wearable devices, watches primarily. In this talk, I would like to present what kind of applications may be developed for this platform, how it differs from regular Android development, what are the limitations, pitfalls and caveats. In the deck I plan to cover the next topics: - Kinds of applications available - API available on the watch itself - API for communication with a connected phone - Watch face development specifics http://uamobile.org/uk/topics/google-wear-os-watch-faces-and-applications-development

1. Google Wear OS watch faces and applications
development
Oleksandr Stepanov
Mobile Lead @ AKQA

2. Who am I
in/oleksandr-stepanov
oleksandr.stepanov@armind.it
Mobile Lead

3. Android platforms

4. Wear OS
(ex Android Wear)

5. Wear OS devices
• 40+ model of watches in sale
• 200+ watches released so far
• 6000+ number of Wear OS apps
in Play Store

6. Screen dimensions
• 240x240 … 480x480
• 400x400 - 24%
• 390x390 - 20%
• Better to use Vector, e.g. SVG

7. Screen shape
11%
89%
“chin”

8. Application type
Standalone apps Watch face

9. Watch face
android.app.Service
android.service.wallpaper.WallpaperService
android.support.wearable.watchface.WatchFaceService
CanvasWatchFaceService Gles2WatchFaceService

10. Watch face Engine
android.service.wallpaper.WallpaperService.Engine
android.support.wearable.watchface.WatchFaceService.Engine
CanvasWatchFaceService.Engine Gles2WatchFaceService.Engine

11. Custom watch face
• class CustomWatchFaceService: CanvasWatchFaceService()
• inner class Engine : CanvasWatchFaceService.Engine()
• Override:
• onCreate(…)
• onPropertiesChanged(…)
• onTimeTick()
• onAmbientModeChanged(…)
• onDraw(…)
• onVisibilityChanged(visible: Boolean)

12. Custom watch face
<service
android:name=".AnalogWatchFaceService"
android:label="@string/analog_name"
android:permission="android.permission.BIND_WALLPAPER" >
<meta-data
android:name="android.service.wallpaper"
android:resource="@xml/watch_face" />
<meta-data
android:name="com.google.android.wearable.watchface.preview"
android:resource="@drawable/preview_analog" />
<meta-data
android:name="com.google.android.wearable.watchface.preview_circular"
android:resource="@drawable/preview_analog_circular" />
<intent-filter>
<action android:name="android.service.wallpaper.WallpaperService" />
<category
android:name=
"com.google.android.wearable.watchface.category.WATCH_FACE" />
</intent-filter>
</service>

13. Custom watch face

14. Complications
Data
Provider
Wear
System
Watch
Face
ComplicationDataComplicationData
Update request

15. Complications

16. Proper Architecture
• MVVM or MVP
• RxJava/RxKotlin
• Architecture Components not available
• Custom technical design

18. Standalone apps

19. Standalone apps
android.app.Activity
android.support.wearable.activity.WearableActivity

20. Standalone apps
<manifest>
...
<uses-feature android:name="android.hardware.type.watch" />
...
<application>
...
<meta-data
android:name="com.google.android.wearable.standalone"
android:value="true" />
...
</application>
</manifest>

21. Standalone apps
• class CustomWearableActivity: WearableActivity()
• Standard Activity lifecycle
• Ambient mode addition
• boolean isAmbient()
• void onEnterAmbient(Bundle ambientDetails)
• void onExitAmbient()
• void onUpdateAmbient()
• void setAmbientEnabled()

22. Demo

23. Ambient mode
Burn-in protection
• OLED and AMOLED screens
• EXTRA_BURN_IN_PROTECTION flag
in onEnterAmbient(…)
• Avoid having solid blobs
16x16 size in ambient
• Avoid placing elements or
frame on the edge

24. Ambient mode
Burn-in protection
Off On

25. Low-bit Ambient mode
• EXTRA_LOWBIT_AMBIENT flag in
onEnterAmbient(…)
• When on, only few colors
available in ambient mode
• Anti-aliasing must be
disabled

26. Connected app
on handheld
phone or tablet

27. Wear OS app on phone
• Wear OS watch must be paired
with phone
• Pairing happens through Wear
OS app
• Android & iOS versions available
• Watch is connected via BLE

28. Connected app
• Applications shares package
name
• Distributed in one app on Play
Store
• … but in separate APKs
• Play Store on the watch and
phone downloads own package.

29. Connected app API
• Data Layer API
• DataClient
• DataMap <—> DataMapItem <—> DataItem
• MessageClient
• Only for connected nodes
• <100k of data
• ChannelClient
• Transfer data using streams
• Media data

30. Connected app API

31. Handheld statistic
2 out of 3 1 out of 3

32. iOS Connected app API
Data Layer API

33. iOS Connected app API

34. iOS Connected app API
Central Peripheral

35. iOS Connected app API
• BLE 4.0 Services & Characteristics (GATT)
• BLE 4.1 L2CAP Connection-oriented Channels
✓ iOS since 11 version
– Android announced in Q

36. iOS Connected app API

37. iOS Connected app API
• Firestore Database
• Realtime Database
• Cloud Storage
• Cloud Messaging (push notifications)

38. !
Bonus

39. !

40. Limited edition

41. Wear OS LE
⛔ Google Play Store
‣ Huawei and Mobvoi
⛔ Firebase
⛔ Google Authentication
⛔ Google Play Services version 10.2.0

42. Wear OS LE
• Wearable API via GoogleApiClient
• Data Layer API
• FusedLocationProvider
• Google Fit limited support

43. Thank you !