sample-app-guide

Sample App Guide (Android)

Build an Android DAT app with registration, sessions, camera streaming, and photo capture.

Project setup

Create an Android Studio app project.
Add the DAT Maven repository and dependencies.
Configure AndroidManifest.xml for registration callbacks plus APPLICATION_ID and CLIENT_TOKEN.
Initialize Wearables in your Application.

Suggested app structure

app/src/main/java/com/example/myapp/
├── MyApplication.kt
├── MainActivity.kt
├── session/
│   └── SessionViewModel.kt
└── ui/
    ├── RegistrationScreen.kt
    └── CameraScreen.kt

Registration and session creation

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        lifecycleScope.launch {
            Wearables.registrationState.collect { state ->
                // Update registration UI
            }
        }
    }

    fun register() {
        Wearables.startRegistration(this)
    }
}

DeviceSession.start() is fire-and-forget. Attach the camera from the session-state collector once the session reports DeviceSessionState.STARTED; adding a capability to an IDLE session fails with DeviceSessionError.SESSION_IDLE.

class SessionViewModel : ViewModel() {
    private var session: DeviceSession? = null
    private var camera: Camera? = null

    fun startCameraSession() {
        Wearables.createSession(AutoDeviceSelector()).fold(
            onSuccess = { createdSession ->
                session = createdSession

                viewModelScope.launch {
                    createdSession.errors.collect { error -> showError(error.description) }
                }
                viewModelScope.launch {
                    createdSession.state.collect { state ->
                        when (state) {
                            DeviceSessionState.STARTED -> attachCamera(createdSession)
                            DeviceSessionState.STOPPED -> clearSession(createdSession)
                            else -> Unit
                        }
                    }
                }

                createdSession.start()
            },
            onFailure = { error, _ -> showError(error.description) },
        )
    }

    private fun attachCamera(activeSession: DeviceSession) {
        if (camera != null) return
        activeSession.addCamera(
            StreamConfiguration(videoQuality = VideoQuality.MEDIUM, frameRate = 24),
        ).fold(
            onSuccess = { addedCamera ->
                camera = addedCamera
                addedCamera.stream.start().onFailure { error, _ ->
                    showError(error.description)
                }
            },
            onFailure = { error, _ -> showError(error.description) },
        )
    }

    private fun clearSession(stoppedSession: DeviceSession) {
        if (session !== stoppedSession) return
        camera = null
        session = null
    }
}

Observe frames and capture photos

viewModelScope.launch {
    camera?.stream?.videoStream?.collect { frame ->
        // Render preview
    }
}

fun capturePhoto() {
    viewModelScope.launch {
        camera?.stream?.capturePhoto()
            ?.onSuccess { photoData ->
                when (photoData) {
                    is PhotoData.Bitmap -> savePhoto(photoData.bitmap)
                    is PhotoData.HEIC -> saveHeic(photoData.data)
                }
            }
            ?.onFailure { error, _ ->
                showCaptureError(error.description)
            }
    }
}

Shutdown

fun stopCameraSession() {
    camera?.stop()
    session?.stop()
    camera = null
    session = null
}

Testing with MockDeviceKit

Use MockDeviceKit to simulate linking glasses, permission state, and camera media without physical hardware. See MockDevice Testing for setup details.