---
name: sample-app-guide
description: Building a complete DAT app with session creation, camera streaming, and photo capture
---

# Sample App Guide (Android)

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

Pair this with the [CameraAccess sample](https://github.com/facebook/meta-wearables-dat-android/tree/main/samples).

## Project setup

1. Create an Android Studio app project.
2. Add the DAT Maven repository and dependencies.
3. Configure `AndroidManifest.xml` for registration callbacks and `APPLICATION_ID`.
4. Initialize `Wearables` in your `Application`.

## Suggested app structure

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

## Registration and session creation

```kotlin
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)
    }
}
```

```kotlin
class SessionViewModel : ViewModel() {
    private var session: Session? = null
    private var stream: Stream? = null

    fun startCameraSession() {
        val createdSession = Wearables.createSession(AutoDeviceSelector()).getOrElse { error ->
            throw IllegalStateException(error.description)
        }
        createdSession.start()
        session = createdSession

        stream = createdSession.addStream(
            StreamConfiguration(videoQuality = VideoQuality.MEDIUM, frameRate = 24),
        ).getOrElse { error ->
            throw IllegalStateException(error.description)
        }.also { addedStream ->
            addedStream.start().getOrElse { error ->
                throw IllegalStateException(error.description)
            }
        }
    }
}
```

## Observe frames and capture photos

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

fun capturePhoto() {
    viewModelScope.launch {
        stream?.capturePhoto()
            ?.onSuccess { photoData ->
                savePhoto(photoData.data)
            }
            ?.onFailure { error, _ ->
                showCaptureError(error.description)
            }
    }
}
```

## Shutdown

```kotlin
fun stopCameraSession() {
    stream?.stop()
    session?.stop()
    stream = null
    session = null
}
```

## Testing with MockDeviceKit

Use `MockDeviceKit` to simulate linking glasses, permission state, and camera media without physical hardware. See [MockDevice Testing](mockdevice-testing.md) for setup details.

## Links

- [CameraAccess sample](https://github.com/facebook/meta-wearables-dat-android/tree/main/samples)
- [Android integration guide](https://wearables.developer.meta.com/docs/build-integration-android)
- [Developer documentation](https://wearables.developer.meta.com/docs/develop/)