flutter real time face detection

Question

I am currently developing an app that requires real time face detection. Right now I have the mlkit library in the app and I am using the firebase face detector. At the moment, it produces an error every time I try to detect a face from file:

DynamiteModule(13840): Local module descriptor class for com.google.android.gms.vision.dynamite.face not found.

As for the real time part, I tried using the RepaintBoundary in flutter to get a screenshot of the camera widget (almost)every frame and convert it into a binary file for face detection. But for some reason, flutter crashed every time I tried to screenshot the camera widget. It worked for other widgets.

After coming across both of these problems and spending quite a while trying to solve them, I've been thinking about just doing the camera part of the app in android/iOS native code(I would do this with OpenCV so that I can have real time detection). Is there a way I could use platform channels to implement a camera view in kotlin and swift and import that to a flutter widget? Or is there another easier way to implement this?

Answer 1

For the real-time access to camera image stream, I answered in another question How to access camera frames in flutter quickly that you want to use CameraController#startImageStream

import 'package:camera/camera.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

void main() => runApp(MaterialApp(home: _MyHomePage()));

class _MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<_MyHomePage> {
  dynamic _scanResults;
  CameraController _camera;

  bool _isDetecting = false;
  CameraLensDirection _direction = CameraLensDirection.back;

  @override
  void initState() {
    super.initState();
    _initializeCamera();
  }

  Future<CameraDescription> _getCamera(CameraLensDirection dir) async {
    return await availableCameras().then(
      (List<CameraDescription> cameras) => cameras.firstWhere(
            (CameraDescription camera) => camera.lensDirection == dir,
          ),
    );
  }

  void _initializeCamera() async {
    _camera = CameraController(
      await _getCamera(_direction),
      defaultTargetPlatform == TargetPlatform.iOS
          ? ResolutionPreset.low
          : ResolutionPreset.medium,
    );
    await _camera.initialize();
    _camera.startImageStream((CameraImage image) {
      if (_isDetecting) return;
      _isDetecting = true;
      try {
        // await doOpenCVDectionHere(image)
      } catch (e) {
        // await handleExepction(e)
      } finally {
        _isDetecting = false;
      }
    });
  }
  Widget build(BuildContext context) {
    return null;
  }
}