如何在Flutter中使用Google ML Kit实现人脸头部姿态检测？

之前我在Flutter应用中使用Firebase ML Kit获取用户头部左右、上下的位置，当时实现较为简便，但如今我无法找到使用Google ML Kit实现相同功能的方法。

以下是我此前基于Firebase ML Kit的相关代码：

初始化实例 #

final FaceExpressionProvider _expressionProvider = FaceExpressionProvider();
final FaceExpressionUtils _expressionVerifier = FaceExpressionUtils();

表情监听处理逻辑 #

void _expressionListener() {
    final Face face = _expressionProvider.face;
    if (_controller == null) _controller = _expressionProvider.cameraController;
    var state = _expressionVerifier.process(face);
    _instruction = _instructionMapper(state);
    if (state == Instructions.VerificationComplete) {
      _captureImage();
    }

    setState(() {});
}

指令映射方法 #

FaceMovementInstruction _instructionMapper(Instructions instruction) {
    final instructions = [
      FaceMovementInstruction(
          AppLocalizations.of(context).faceNotFound.toUpperCase(),
          "facenotfound"),
      FaceMovementInstruction(
          AppLocalizations.of(context).lookLeft.toUpperCase(), "lookleft"),
      FaceMovementInstruction(
          AppLocalizations.of(context).lookRight.toUpperCase(), "lookright"),
      FaceMovementInstruction(
          AppLocalizations.of(context).smilePlease.toUpperCase(), "smile"),
      FaceMovementInstruction(
          AppLocalizations.of(context).verified.toUpperCase(), "verified"),
      FaceMovementInstruction(
          AppLocalizations.of(context).error.toUpperCase(), "error"),
    ];
    switch (instruction) {
      case Instructions.ShowFace:
        return instructions[0];
      case Instructions.LookLeft:
        return instructions[1];
        break;
      case Instructions.LookRight:
        return instructions[2];
        break;
      case Instructions.SmilePlease:
        return instructions[3];
        break;
      case Instructions.AnalyzingResults:
        break;
      case Instructions.VerificationComplete:
        return instructions[4];
        break;
    }
    return instructions[5];
}

此前使用的依赖库：import 'package:firebase_ml_vision/firebase_ml_vision.dart';

内容的提问来源于stack exchange，提问作者A. K. M. Shahab Uddin