Flutter Scalable OCR 的使用

flutter_scalable_ocr 是一个基于 Google ML Kit 文本识别功能的 Flutter 插件，旨在解决从相机的部分区域而不是整个屏幕获取文本的问题。本文将详细介绍如何在 Flutter 项目中使用这个插件。

功能特性

• 从相机的狭窄窗口扫描文本，而不是整个屏幕。
• 提供两种方法：
  • getScannedText: 返回读取的文本字符串。
  • getRawData: 返回包含 TextElement 对象的列表。
• 支持缩放和手势操作。

使用步骤

1. 添加依赖

首先，在你的 pubspec.yaml 文件中添加 flutter_scalable_ocr 依赖：

dependencies:
  flutter_scalable_ocr: ^1.0.1

然后运行 flutter pub get 来安装依赖。

2. 导入包

在需要使用该插件的 Dart 文件中导入它：

import 'package:flutter_scalable_ocr/flutter_scalable_ocr.dart';

3. 配置权限

由于该插件依赖于 camera 包，请确保在 Android 和 iOS 上配置了相应的权限。参考 Camera Package 的文档来设置权限。

4. 使用示例

以下是一个完整的示例代码，展示了如何集成 flutter_scalable_ocr 到你的 Flutter 应用中：

import 'dart:async';
import 'dart:developer';

import 'package:flutter/material.dart';
import 'package:flutter_scalable_ocr/flutter_scalable_ocr.dart';

void main() {
  WidgetsFlutterBinding.ensureInitialized();
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Scalable OCR',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Scalable OCR'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

  [@override](/user/override)
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  String text = "";
  final StreamController<String> controller = StreamController<String>();
  bool torchOn = false;
  int cameraSelection = 0;
  bool lockCamera = true;
  bool loading = false;
  final GlobalKey<ScalableOCRState> cameraKey = GlobalKey<ScalableOCRState>();

  void setText(value) {
    controller.add(value);
  }

  [@override](/user/override)
  void dispose() {
    controller.close();
    super.dispose();
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.start,
          children: <Widget>[
            !loading
                ? ScalableOCR(
                    key: cameraKey,
                    torchOn: torchOn,
                    cameraSelection: cameraSelection,
                    lockCamera: lockCamera,
                    paintboxCustom: Paint()
                      ..style = PaintingStyle.stroke
                      ..strokeWidth = 4.0
                      ..color = const Color.fromARGB(153, 102, 160, 241),
                    boxLeftOff: 5,
                    boxBottomOff: 2.5,
                    boxRightOff: 5,
                    boxTopOff: 2.5,
                    boxHeight: MediaQuery.of(context).size.height / 3,
                    getRawData: (value) {
                      inspect(value);
                    },
                    getScannedText: (value) {
                      setText(value);
                    })
                : Padding(
                    padding: const EdgeInsets.all(17.0),
                    child: Container(
                      decoration: BoxDecoration(
                        color: Colors.white,
                        borderRadius: BorderRadius.circular(10),
                      ),
                      height: MediaQuery.of(context).size.height / 3,
                      width: MediaQuery.of(context).size.width,
                      child: const Center(
                        child: CircularProgressIndicator(),
                      ),
                    ),
                  ),
            StreamBuilder<String>(
              stream: controller.stream,
              builder: (BuildContext context, AsyncSnapshot<String> snapshot) {
                return Result(text: snapshot.data ?? "");
              },
            ),
            Column(
              children: [
                ElevatedButton(
                    onPressed: () {
                      setState(() {
                        loading = true;
                        cameraSelection = cameraSelection == 0 ? 1 : 0;
                      });
                      Future.delayed(const Duration(milliseconds: 150), () {
                        setState(() {
                          loading = false;
                        });
                      });
                    },
                    child: const Text("Switch Camera")),
                ElevatedButton(
                    onPressed: () async {
                      setState(() {
                        loading = true;
                        torchOn = !torchOn;
                      });
                      Future.delayed(const Duration(milliseconds: 150), () {
                        setState(() {
                          loading = false;
                        });
                      });
                    },
                    child: const Text("Toggle Torch")),
                ElevatedButton(
                    onPressed: () {
                      setState(() {
                        loading = true;
                        lockCamera = !lockCamera;
                      });
                      Future.delayed(const Duration(milliseconds: 150), () {
                        setState(() {
                          loading = false;
                        });
                      });
                    },
                    child: const Text("Toggle Lock Camera")),
              ],
            )
          ],
        ),
      ),
    );
  }
}

class Result extends StatelessWidget {
  const Result({
    Key? key,
    required this.text,
  }) : super(key: key);

  final String text;

  [@override](/user/override)
  Widget build(BuildContext context) {
    return Text("Readed text: $text");
  }
}