Barcode Scanner using firebase ML + imageStream

[irvan hendrik]

hi, I have trouble on using Firebase ML.

Here is my code:

import 'dart:typed_data';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:camera/camera.dart';
import 'dart:async';
import 'package:firebase_ml_vision/firebase_ml_vision.dart';
final BarcodeDetector _barcodeDetector =
    FirebaseVision.instance.barcodeDetector();
String data = 'EMPTY DATA';

class ScanScreen extends StatefulWidget {
  static String id = 'scan_screen';
  //final CameraDescription camera = cameras.first;
  @override
  _ScanScreenState createState() => _ScanScreenState();
}

class _ScanScreenState extends State<ScanScreen> {
  CameraController _controller;
  Future<void> _initializeControllerFuture;
  CameraImage _savedImage;
  bool _cameraInitialized = false;
  void _initializeCamera() async {
    List<CameraDescription> cameras = await availableCameras();

    _controller = CameraController(
      cameras[0],
      ResolutionPreset.medium,
    );
    _initializeControllerFuture = _controller.initialize().then((_) async {
      // Start ImageStream
      await _controller
          .startImageStream((CameraImage image) => _processCameraImage(image));
      setState(() {
        _cameraInitialized = true;
      });
    });
  }

  void _processCameraImage(CameraImage image) async {
    setState(() async {
      _savedImage = image;
      final barcodes =
          await _barcodeDetector.detectInImage(FirebaseVisionImage.fromBytes(
        _concatenatePlanes(image.planes),
        FirebaseVisionImageMetadata(
          rawFormat: image.format.raw,
          size: Size(image.width.toDouble(), image.height.toDouble()),
          rotation: ImageRotation.rotation0,
          planeData: image.planes.map(
            (plane) => FirebaseVisionImagePlaneMetadata(
              bytesPerRow: plane.bytesPerRow,
              height: plane.height,
              width: plane.width,
            ),
          ),
        ),
      ));
      if (barcodes!=null && barcodes.length>0)
        {
          print(barcodes);
          data=barcodes.toString();
        }
      else{
        print ('no barcode');
        data='no barcode found';
      }
    });
  }

  Uint8List _concatenatePlanes(List<Plane> planes) {
    final WriteBuffer allBytes = WriteBuffer();
    planes.forEach((plane) => allBytes.putUint8List(plane.bytes));
    return allBytes.done().buffer.asUint8List();
  }

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

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final size = MediaQuery.of(context).size;
    final deviceRatio = size.width / size.height;

    return Scaffold(
      appBar: AppBar(
        title: Text('Scan Product'),
      ),
      body: Container(
        color: Colors.black,
        child: Column(
          children: [
            Expanded(
              flex: 2,
              child: Stack(
                children: [
                  MaterialApp(
                    home: Padding(
                      padding:
                          EdgeInsets.symmetric(horizontal: 7.0, vertical: 10.0),
                      child: AspectRatio(
                        aspectRatio: _controller.value.aspectRatio,
                        child: CameraPreview(_controller),
                      ),
                    ),
                  ),
//                  Positioned.fill(
//                      child: Opacity(
//                    opacity: 0.3,
//                    child: Image.network(
//                      'https://picsum.photos/3000/4000',
//                      fit: BoxFit.fill,
//                    ),
//                  ))
                ],
              ),
            ),
            SizedBox(
              height: 10.0,
            ),
            Expanded(
              flex: 2,
              child: Container(
                color: Colors.deepPurple,
                child: Text(data,style: TextStyle(
                  fontSize: 50.0,
                  fontWeight: FontWeight.bold,
                ),),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

I want to achieve:

where the top part is the camera and the bottom part is the barcode data captured from the camera above it..

Can any one help me solve this issue?

Thanks.

Irvan

[Suzuki Tomohiro]

The problem is processCameraImage is never called unexpectedly. Is this correct?

Do you observe _cameraInitialized is set to true? (Set breakpoint to the line that sets the variable to true)

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[irvan hendrik]

I have the processCameraImage in the _initializedCamera function which run in initstate function.

Can you elaborate more on the error that you saw?

Thanks. 

Irvan.