Flutter机器学习扫描插件fl_mlkit_scanning的使用

fl_mlkit_scanning 是一个基于 Google ML Kit 实现的快速稳定扫码功能的 Flutter 插件，支持 Android 和 iOS 平台。该插件依赖于 fl_camera 插件来处理相机相关的功能。

使用

1. 添加相机权限

对于 iOS，需要在 Info.plist 文件中添加相机权限：

<key>NSCameraUsageDescription</key>
<string>是否允许FlMlKitScanning使用你的相机？</string>

2. 预览

以下是一个简单的示例，展示如何使用 FlMlKitScanning 进行扫码预览：

import 'package:flutter/material.dart';
import 'package:fl_mlkit_scanning/fl_mlkit_scanning.dart';
import 'package:toast/toast.dart';

class FlMlKitScanningPage extends StatefulWidget {
  const FlMlKitScanningPage({Key? key}) : super(key: key);

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

class _FlMlKitScanningPageState extends State<FlMlKitScanningPage> {
  late FlMlKitScanningController controller;

  @override
  void initState() {
    super.initState();
    controller = FlMlKitScanningController();
  }

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Fl MlKit Scanning')),
      body: FlMlKitScanning(
        frequency: 500, // 解析频率，单位为毫秒
        camera: controller.camera, // 默认为后摄像头
        resolution: CameraResolution.high, // 预览分辨率
        autoScanning: false, // 是否自动扫描
        overlay: const ScannerLine(), // 显示在预览上层
        updateReset: false, // 更新组件时是否重置相机
        fit: BoxFit.fitWidth, // 相机预览位置
        onFlashChanged: (FlashState state) {
          showToast('$state', duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM);
        },
        onZoomChanged: (double zoom) {
          showToast('Zoom: $zoom', duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM);
        },
        uninitialized: Container(
          color: Colors.black,
          alignment: Alignment.center,
          child: const Text('Camera not initialized', style: TextStyle(color: Colors.white)),
        ),
        barcodeFormats: <BarcodeFormat>[BarcodeFormat.qr_code], // 识别类型
        onDataChanged: (AnalysisImageModel data) {
          final List<Barcode>? barcodes = data.barcodes;
          if (barcodes != null && barcodes.isNotEmpty) {
            Navigator.of(context).pop(barcodes);
          }
        },
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          controller.toggleFlash(); // 切换闪光灯
        },
        child: Icon(Icons.flash_on),
      ),
    );
  }
}

3. 方法

以下是 FlMlKitScanningController 提供的一些常用方法：

void func() {
  // 设置识别码类型
  controller.setBarcodeFormat();

  // 识别图片字节
  controller.scanningImageByte();

  // 打开/关闭闪光灯
  controller.setFlashMode();

  // 相机缩放
  controller.setZoomRatio();

  // 暂停扫描
  controller.pauseScanning();

  // 开始扫描
  controller.startScanning();
}

示例代码

以下是一个完整的示例项目，展示了如何使用 fl_mlkit_scanning 插件进行扫码和图片识别：

import 'package:example/image_scanning.dart';
import 'package:example/mlkit_scanning.dart';
import 'package:fl_extended/fl_extended.dart';
import 'package:fl_mlkit_scanning/fl_mlkit_scanning.dart';
import 'package:flutter/material.dart';
import 'package:permission_handler/permission_handler.dart';

void main() {
  WidgetsFlutterBinding.ensureInitialized();
  runApp(MaterialApp(
      navigatorKey: FlExtended().navigatorKey,
      scaffoldMessengerKey: FlExtended().scaffoldMessengerKey,
      debugShowCheckedModeBanner: false,
      theme: ThemeData.light(useMaterial3: true),
      darkTheme: ThemeData.dark(useMaterial3: true),
      home: _App(),
      title: 'FlMlKitScanning'));
}

class _App extends StatefulWidget {
  @override
  _AppState createState() => _AppState();
}

class _AppState extends State<_App> {
  List<Barcode> list = [];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBarText('Fl MlKit Scanning'),
        body: Universal(width: double.infinity, children: [
          ElevatedText(onPressed: openCamera, text: 'Turn on camera scanning'),
          ElevatedText(onPressed: scanImage, text: 'Image scanning'),
          const SizedBox(height: 30),
          CodeBox(list)
        ]));
  }

  void scanImage() {
    push(const ImageScanningPage());
  }

  Future<void> openCamera() async {
    bool permission = await getPermission(Permission.camera);
    if (permission) {
      final List<Barcode>? data = await push(const FlMlKitScanningPage());
      if (data != null) {
        list = data;
        setState(() {});
      }
    }
  }
}

class CodeBox extends StatelessWidget {
  const CodeBox(this.list, {super.key, this.expanded = true});

  final List<Barcode> list;
  final bool expanded;

  @override
  Widget build(BuildContext context) {
    return Universal(
        expanded: expanded,
        isScroll: expanded,
        children: list.builderEntry((MapEntry<int, Barcode> entry) {
          return Column(children: [
            Text('NO.${entry.key + 1}'),
            const SizedBox(height: 6),
            Text('value:${entry.value.value}').sizedBox(width: double.infinity),
            const SizedBox(height: 6),
            Text('type:${entry.value.type}').sizedBox(width: double.infinity),
            Text('boundingBox:${entry.value.boundingBox?.size}')
                .sizedBox(width: double.infinity),
            Text('boundingBox:${entry.value.boundingBox}')
                .sizedBox(width: double.infinity),
            Text('corners:${entry.value.corners}')
                .sizedBox(width: double.infinity),
          ]);
        }));
  }
}

class AppBarText extends AppBar {
  AppBarText(String text, {super.key})
      : super(
            elevation: 0,
            title: BText(text, fontSize: 18, fontWeight: FontWeight.bold));
}

class TextBox extends StatelessWidget {
  final dynamic keyName;
  final dynamic value;

  const TextBox(this.keyName, this.value, {super.key});

  @override
  Widget build(BuildContext context) {
    return Visibility(
        visible: value != null &&
            value.toString().isNotEmpty &&
            value.toString() != 'null',
        child: Container(
            margin: const EdgeInsets.all(10),
            child: Text('$keyName = $value')));
  }
}

Future<bool> getPermission(Permission permission) async {
  PermissionStatus status = await permission.status;
  if (status.isGranted) {
    return true;
  } else {
    status = await permission.request();
    if (!status.isGranted) openAppSettings();
    return status.isGranted;
  }
}

class ElevatedText extends StatelessWidget {
  const ElevatedText({super.key, this.onPressed, required this.text});

  final VoidCallback? onPressed;
  final String text;

  @override
  Widget build(BuildContext context) =>
      ElevatedButton(onPressed: onPressed, child: Text(text));
}

class ElevatedIcon extends StatelessWidget {
  const ElevatedIcon({super.key, this.onPressed, required this.icon});

  final VoidCallback? onPressed;
  final IconData icon;

  @override
  Widget build(BuildContext context) =>
      ElevatedButton(onPressed: onPressed, child: Icon(icon));
}

以上代码展示了如何使用 fl_mlkit_scanning 插件进行扫码和图片识别，并处理相机权限和结果显示。希望对你有所帮助！