ml vision

import 'dart:typed_data';

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

class CameraPreviewScanner extends StatefulWidget {
  @override
  _CameraPreviewScannerState createState() => _CameraPreviewScannerState();
}

class _CameraPreviewScannerState extends State<CameraPreviewScanner> {
  List<CameraDescription> cameras;
  CameraController controller;
  bool isReady = false;

//  CameraController _camera;
  bool _isDetecting = false;
  final _barcodeDetector = FirebaseVision.instance.barcodeDetector();

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

  void _initializeCamera() async {
    cameras = await availableCameras();
    controller = new CameraController(cameras[0], ResolutionPreset.medium);
    await controller.initialize();
    setState(() {
      isReady = true;
    });
    startCameraForScanning(cameras[0]);
  }

  Future<void> startCameraForScanning(CameraDescription description) {
    return controller.startImageStream(
      (CameraImage image) {
        if (_isDetecting) return;

        FirebaseVisionImage firebaseImage = FirebaseVisionImage.fromBytes(
          _concatenatePlanes(image.planes),
          _buildMetaData(image,
              _rotationIntToImageRotation(description.sensorOrientation)),
        );

        _barcodeDetector.detectInImage(firebaseImage).then(
          (List<Barcode> barcodes) {
            if (barcodes.isNotEmpty) {
              setState(() {
                _isDetecting = true;
              });
              Scaffold.of(context).showSnackBar(
                  SnackBar(content: Text("${barcodes[0].rawValue}")));
            }
          },
        ).whenComplete(() async {
          await Future.delayed(Duration(seconds: 5));
          setState(() {
            _isDetecting = false;
          });
        });
      },
    );
  }

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

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

  FirebaseVisionImageMetadata _buildMetaData(
    CameraImage image,
    ImageRotation rotation,
  ) {
    return FirebaseVisionImageMetadata(
      rawFormat: image.format.raw,
      size: Size(image.width.toDouble(), image.height.toDouble()),
      rotation: rotation,
      planeData: image.planes.map(
        (Plane plane) {
          return FirebaseVisionImagePlaneMetadata(
            bytesPerRow: plane.bytesPerRow,
            height: plane.height,
            width: plane.width,
          );
        },
      ).toList(),
    );
  }

  ImageRotation _rotationIntToImageRotation(int rotation) {
    switch (rotation) {
      case 0:
        return ImageRotation.rotation0;
      case 90:
        return ImageRotation.rotation90;
      case 180:
        return ImageRotation.rotation180;
      default:
        assert(rotation == 270);
        return ImageRotation.rotation270;
    }
  }

  Widget _buildImage() {
    return AspectRatio(
      aspectRatio: controller.value.aspectRatio,
      child: CameraPreview(controller),
    );
  }

  @override
  Widget build(BuildContext context) {
    if (!isReady) {
      return Container();
    }
    return Container(
      child: _buildImage(),
    );
  }

  @override
  void deactivate() {
    controller.stopImageStream();
    super.deactivate();
  }

  @override
  void dispose() {
    controller.dispose().then((_) {
      _barcodeDetector.close();
    });
    super.dispose();
  }
}