Android 2D App Porting to Horizon OS
When to Use
Use this skill when:
- Porting an existing Android 2D app to run on Meta Quest headsets
- Adapting a mobile Android app for Horizon OS panels
- Troubleshooting input, layout, or compatibility issues with a 2D app on Quest
- Preparing an Android app for Horizon Store submission
- Evaluating whether an existing Android app is compatible with Horizon OS
Overview
Horizon OS is built on Android (AOSP) and can run standard Android applications inside panels -- floating 2D windows positioned in 3D space. Most well-built Android apps work on Quest with minimal changes, but several areas require attention:
- Input: There is no touchscreen. Users interact via controller pointer (ray-casting), hand tracking, or connected peripherals.
- Layout: Apps run in resizable panels, not full-screen on a fixed display.
- Design: Apps must meet Horizon OS design requirements for Horizon Store approval.
- Performance: Quest uses a mobile GPU (Adreno) with thermal constraints.
The goal of porting is to make the app feel native to the Quest experience while preserving existing functionality.
Porting Workflow
Step 1: Initial Testing
Invoke hzdb (the Quest device CLI) via npx -y @meta-quest/hzdb <args> — no global install needed; npx fetches the latest published version on demand.
If using npx, use npx -y @meta-quest/hzdb as an alternative to calling hzdb found in this doc.
Install the existing APK on a connected Quest device and test basic functionality:
hzdb app install path/to/your-app.apk
hzdb app launch com.example.yourappNote any immediate issues: crashes, black screens, input problems, or layout breakage.
Step 2: Input Adaptation
The most common porting issue is input. Touch events are translated from the controller pointer, but:
- Hover states are now visible (users point before clicking)
- Scrolling uses the thumbstick, not swipe gestures
- Multi-touch gestures (pinch-to-zoom) do not translate directly
- Tap targets must be large enough for pointer accuracy (48dp minimum)
See Input Adaptation Reference for detailed guidance.
Step 3: Layout Adjustment
Panels are resizable and can have various aspect ratios. Your app must handle:
- Dynamic width and height changes
- Landscape and portrait orientations
- Different effective DPI values
Use responsive layout strategies such as ConstraintLayout or Jetpack Compose. See Panel Layout Reference.
Step 4: Gradle and Manifest Updates
Update your build configuration to target Horizon OS:
// build.gradle.kts
android {
defaultConfig {
minSdk = 29 // Android 10 minimum
targetSdk = 34 // API 34 or higher required for all new 2D panel apps
}
}Add required manifest entries for device targeting. See Gradle Setup Reference.
Step 5: Input Testing
Test with all supported input methods:
- Controller: point-and-click, thumbstick scroll, trigger tap
- Hand tracking: pinch-to-select, hand scroll
- Keyboard/mouse: Bluetooth peripherals, system keyboard for text fields
Use the XR Simulator for rapid iteration, then validate on-device.
Step 6: Store Submission
Before submitting to the Horizon Store:
- Verify all Compatibility Requirements
- Test on at least Quest 3 and Quest 2 (if targeting both)
- Confirm the app works in both passthrough and immersive home environments
- Review Meta's content policies and technical requirements
Quick Compatibility Check
Works on Horizon OS
| Feature | Status | Notes |
|---|---|---|
| Standard Android Views | Supported | TextView, RecyclerView, etc. |
| Jetpack Compose | Supported | Full Compose UI toolkit |
| WebView | Supported | Chromium-based |
| Media playback (ExoPlayer) | Supported | Video and audio |
| Networking (HTTP, WebSocket) | Supported | Wi-Fi connectivity |
| Room / SQLite | Supported | Local database |
| WorkManager | Supported | Background tasks |
| Notifications | Supported | Horizon OS notification panel |
| Bluetooth (peripherals) | Supported | Keyboard, mouse, gamepad |
| Android Accessibility APIs | Supported | TalkBack equivalent available |
Restricted or Unavailable
| Feature | Status | Notes |
|---|---|---|
| Camera (front-facing) | Not available | No standard camera in 2D mode |
| Telephony / SMS | Not available | No cellular radio |
| NFC | Not available | No NFC hardware |
| GPS / Fine location | Limited | Wi-Fi-based location only |
| Fingerprint / BiometricPrompt | Not available | Use Meta account auth instead |
| Split-screen (multi-window) | Limited | Use Spatial SDK panels instead |
| Google Play Services | Not available | Use Meta equivalents or alternatives |
| ARCore | Not available | Use Meta Spatial SDK for spatial features |
| Multi-touch gestures | Limited | Single pointer from controller |
Common Issues and Fixes
| Issue | Cause | Fix |
|---|---|---|
| App crashes on launch | Missing Google Play Services dependency | Remove or make GMS optional |
| Buttons too small to tap | Touch targets under 48dp | Increase minimum tap target size |
| No scroll in lists | Swipe-based scroll not triggered | Ensure RecyclerView/LazyColumn handles generic scroll events |
| Keyboard doesn't appear | Custom input field not using InputConnection | Use standard EditText or TextField |
| Layout broken | Fixed-size layout assumptions | Use responsive layouts with ConstraintLayout or Compose |
| App requests unavailable permissions | Camera, telephony, etc. | Guard with hasSystemFeature() checks |
| APK rejected for prohibited permissions | Library or plugin silently added a prohibited permission | Run aapt dump permissions your-app.apk, then check prohibited list |
| APK rejected for invalid signature | Signed with v1-only scheme | v2 signing is default in AGP 7.0+; for older AGP, add v2SigningEnabled = true to your signing config |
Key Concepts
Compatibility Mode vs Native Targeting
Apps not specifically targeting Horizon OS run in compatibility mode:
- Fixed panel size (simulating a phone screen)
- Limited resizing
- Basic input translation
Apps that target Horizon OS with proper manifest entries run in native mode:
- Resizable panels
- Full input API support
- Access to Spatial SDK features (optional)
- Better integration with Horizon OS shell
Testing Tools
- hzdb: Command-line tool for installing, launching, and debugging apps on Quest
- XR Simulator: Desktop tool for testing Quest apps without a headset
- Meta Quest Developer Hub (MQDH): GUI tool for device management and debugging
- Android Studio: Full IDE with Quest device support via ADB
Performance Considerations
Quest devices have mobile-class hardware with strict thermal limits:
- GPU: Qualcomm Adreno (varies by Quest model)
- RAM: 6-12 GB shared between system and apps
- Thermal: Sustained workloads may trigger thermal throttling
- Avoid heavy overdraw and complex shader effects in 2D UI
- Minimize background work to reduce power consumption
- Test with representative data loads (large lists, images, etc.)
References
- Compatibility Requirements -- store requirements and API compatibility
- Input Adaptation -- adapting touch to controller and hand input
- Panel Layout -- responsive layout for Horizon OS panels
- Gradle Setup -- build configuration and manifest entries