check method

LivenessResult check(Face face)

Check whether a Face passes basic liveness criteria.

Requires ML Kit configured with enableClassification: true.

Implementation

LivenessResult check(Face face) {
  // Eye open check (requires classification enabled).
  final leftEye = face.leftEyeOpenProbability;
  final rightEye = face.rightEyeOpenProbability;

  if (leftEye != null && leftEye < minEyeOpenProbability) {
    return const LivenessResult(
      isLive: false,
      reason: 'Left eye appears closed',
    );
  }
  if (rightEye != null && rightEye < minEyeOpenProbability) {
    return const LivenessResult(
      isLive: false,
      reason: 'Right eye appears closed',
    );
  }

  // Head pose check — face should be roughly facing the camera.
  final angleX = face.headEulerAngleX; // up/down tilt
  final angleY = face.headEulerAngleY; // left/right turn
  final angleZ = face.headEulerAngleZ; // tilt/roll

  if (angleX != null && angleX.abs() > maxHeadAngle) {
    return const LivenessResult(
      isLive: false,
      reason: 'Head tilted too far up or down',
    );
  }
  if (angleY != null && angleY.abs() > maxHeadAngle) {
    return const LivenessResult(
      isLive: false,
      reason: 'Head turned too far left or right',
    );
  }
  if (angleZ != null && angleZ.abs() > maxHeadAngle) {
    return const LivenessResult(
      isLive: false,
      reason: 'Head tilted to one side',
    );
  }

  return const LivenessResult(isLive: true);
}