✨ Support Camera2 native face detection on Android

Prerequisites

• I have searched existing issues for a similar request.

What problem are you trying to solve?

Android face detection currently needs ML Kit and a pixel stream even though Camera2 can return native face metadata with each capture result.

Proposed API / solution

Keep the existing ObjectOutput API:

const faces = useObjectOutput({
  types: ['face'],
  onObjectsScanned,
})

<Camera outputs={[faces]} {...props} />

Internally, allow a metadata output to contribute session configuration without owning a CameraX UseCase. CameraX 1.7 can configure the shared session:

SessionConfig.Builder(useCases)
  .camera2Interop {
    setCaptureRequestOption(
      CaptureRequest.STATISTICS_FACE_DETECT_MODE,
      bestSupportedMode,
    )
    setRepeatingCaptureCallback(
      executor,
      object : CameraCaptureSession.CaptureCallback() {
        override fun onCaptureCompleted(
          session: CameraCaptureSession,
          request: CaptureRequest,
          result: TotalCaptureResult,
        ) {
          emit(result[CaptureResult.STATISTICS_FACES].orEmpty())
        }
      },
    )
  }
  .build()

Prefer FULL, fall back to SIMPLE, and disable it when only OFF is available.

Alternatives considered

ML Kit via a FrameOutput. It is more capable, but needs another stream and app-side inference.

Platforms this should target

Android

Would you be willing to contribute this?

Yes - I'd like to open a PR.

Additional context

• STATISTICS_FACE_DETECT_MODE, STATISTICS_FACES, and Face
• API 21+, but support is per camera. Only OFF is guaranteed. Android 17 performance-class 34/35/37 primary cameras must expose SIMPLE or FULL.
• SIMPLE gives bounds and score. FULL adds an ID and optional eye/mouth points. Camera2 has no yaw/roll, so use faceID = -1 where unsupported and set the angle flags to false.
• Bounds are sensor active-array coordinates. Normalize crop, zoom, rotation, and mirroring into VisionCamera camera-space; PreviewView.getSensorToViewTransform() handles view mapping.
• ML Kit documents about 60 ms on Pixel 3 in FAST mode. There is no comparable Camera2 latency or power figure. Avoiding ImageAnalysis, YUV delivery, and app-side inference should reduce app CPU and memory bandwidth, but needs device benchmarks.

Submission

• I described the problem, not just the solution.
• I wrote this request in my own words. I did not paste AI-generated proposals.

Start by locating the existing ObjectOutput implementation and Android camera session configuration, then trace how outputs contribute to the shared CameraX session. Use the proposed Camera2 capture metadata and face-detection modes as the behavioral guide. Done means native face metadata reaches the existing API with FULL/SIMPLE fallback and the documented coordinate and unsupported-angle behavior.