如何使用从相机开始图像流的方法 class

Question

我是flutter新手，这是我第一个真正使用的app。这就是我想要实现的目标，当相机指向车牌时，我的应用程序将用于自动检测车牌，对于文本检测部分，我将使用 flutter ml 套件。如果我想在 File 数据类型中输出 10 张图像，我应该如何编写启动图像流方法，然后将其添加到我的 ImagePathList.

我确实对此进行了研究，但我没有找到与我想要实现的目标相关的任何内容，有一些博客文章使用了它，但他们没有正确解释它所以我转向堆栈溢出。

I want the functionality to be like this

这就是我的 camera_screen 的样子

import 'dart:typed_data';
import 'package:flutter/material.dart';
import 'package:firebase_ml_vision/firebase_ml_vision.dart';
import 'package:flutter/services.dart';
import 'package:npgroups/npgroups.dart';
import 'package:society_app/screens/result_screen.dart';
import 'package:society_app/widgets/common_drawer.dart';
import 'package:camera/camera.dart';
import 'dart:async';
import 'package:numeric_keyboard/numeric_keyboard.dart';


class CameraScreen extends StatefulWidget {

  final CameraDescription camera;

  static String id = 'camera_screen';


  CameraScreen({required this.camera});

  @override
  _CameraScreenState createState() => _CameraScreenState();
}

class _CameraScreenState extends State<CameraScreen> {

  Widget buildButton(String buttonText){
    return Container(
      height: MediaQuery.of(context).size.height * 0.1 * 0.85,
      color: Colors.blueAccent,
      child: FlatButton(
          onPressed: () {},
          child: Text(
            buttonText,
            style: TextStyle(
                fontSize: 30.0,
                fontWeight: FontWeight.normal,
                color: Colors.white
            ),
          )
      ),
    );
  }

  late CameraController _controller;
  late Future<void> _initializeControllerFuture;
  late Npgroups _npgroups;
  List imagePathList = [];

  List<String?> detectedWordList = [];

  static const MethodChannel _channel = const MethodChannel('tflite');

  String? resultText;
  late int imageHeight;
  late int imageWidth;



  bool? get isPaused => null;

  @override
  void initState() {
    // TODO: implement initState
    super.initState();

    _controller = CameraController(
      // Get a specific camera from the list of available cameras.
      widget.camera,
      // Define the resolution to use.
      ResolutionPreset.medium,
    );

    _initializeControllerFuture = _controller.initialize();
    initPlatformState();
  }

  Future<void> initPlatformState() async {
    _npgroups = Npgroups(listenToNumplate);
    await _npgroups.startListening();
  }

  @override
  void dispose() {
    // Dispose of the controller when the widget is disposed.
    _controller.dispose();
    super.dispose();
  }

  Future getNumberPlate(image) async {
    FirebaseVisionImage mlImage = FirebaseVisionImage.fromFile(image);
    TextRecognizer recognizeText = FirebaseVision.instance.textRecognizer();
    VisionText readText = await recognizeText.processImage(mlImage);

    for (TextBlock block in readText.blocks) {
      for (TextLine line in block.lines) {
        for (TextElement word in line.elements) {
          resultText = word.text;
          _npgroups.processNumberplate(resultText!);
        }
      }
    }

    if (resultText == null) {
      print('null');
    } else {
      detectedWordList.add(resultText);
    }
  }


  listenToNumplate(String numplate) {
    //Consume the numplate
  }



  @override
  Widget build(BuildContext context) {
    return Scaffold(
      drawer: CommonDrawer(),
      appBar: AppBar(
        title: Text(
            'Camera'
        ),
      ),
      body: FutureBuilder<void>(
        future: _initializeControllerFuture,
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.done) {
              return Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Stack(
                    children: [
                      AspectRatio(aspectRatio: _controller.value.aspectRatio - 0.2,
                          child: CameraPreview(_controller)),
                      Positioned(
                        bottom: 10,
                        left: 5,
                        child: Row(
                          children: [
                            VehicleButton(icon: Icons.motorcycle_outlined,),
                            SizedBox(width: 35),
                            VehicleButton(icon: Icons.directions_car,)
                          ],
                        ),
                      )
                    ],
                  ),
                  Row(
                    children: [
                      Container(
                        width: MediaQuery.of(context).size.width * .99,
                        child: Table(
                          children: [
                            TableRow(
                              children: [
                                buildButton('1'),
                                buildButton('2'),
                                buildButton('3')
                              ]
                            ),
                            TableRow(
                                children: [
                                  buildButton('4'),
                                  buildButton('5'),
                                  buildButton('6')
                                ]
                            ),
                            TableRow(
                                children: [
                                  buildButton('7'),
                                  buildButton('8'),
                                  buildButton('9')
                                ]
                            ),
                            TableRow(
                                children: [
                                  buildButton('↻'),
                                  buildButton('0'),
                                  buildButton('⌫')
                                ]
                            ),
                          ],
                        ),
                      )
                    ],
                  )

                ],
              );

          } else {
            // Otherwise, display a loading indicator.
            return const Center(child: CircularProgressIndicator());
          }
        },
      ),
    );
  }

  }

class VehicleButton extends StatelessWidget {

  final IconData icon;

    VehicleButton({required this.icon});

  @override
  Widget build(BuildContext context) {
    return ElevatedButton(
      onPressed: () {},
      child: Padding(
        padding: const EdgeInsets.symmetric(vertical: 17, horizontal: 50),
        child: Icon(
        icon,
        color: Colors.white,
        size: 45,
    ),
      ),
      style: ButtonStyle(
        shape: MaterialStateProperty.all(RoundedRectangleBorder(borderRadius: BorderRadius.circular(10.0)))
      ),
    );
  }
}

Blockquote

Answer 1

你可以这样做

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

    controller = CameraController(widget.cameras[0], ResolutionPreset.medium,
        enableAudio: false);

    controller.initialize().then((_) async {
      if (!mounted) {
        return;
      }

      setState(() {});

          await controller.startImageStream((CameraImage availableImage) async {
            _scanText(availableImage);
          });

  }

如何使用从相机开始图像流的方法 class

How To Use Start Image stream method from the camera class

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