[Flutter] QR 코드 생성, 스캔

1. QR 코드 생성 (qr_flutter)

qr_flutter 라이브러리를 이용하면, 쉽게 원하는 QR코드를 만들수 있다.

예제 코드

return Center(
  child: Column(
    children: [
      QrImage(
        data: "https://www.daum.net/",
        backgroundColor: Colors.white,
        size: 200,
      )
    ],
  ),
);

data부분에 원하는 값만 넣어주면 만들어진다.

결과 화면

 

https://pub.dev/packages/qr_flutter

qr_flutter | Flutter Package

 

 

 

2. QR코드 스캔 (qr_code_scanner)

초간단한 QR생성기보다 조금 복잡하고 다양한 기능이 있는 QR스캐너 라이브러리를 알아보자.

qr_code_scanner 를 이용해서 스캐너화면을 구현할 수 있다.

 

예제 코드

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: [
          Expanded(
            flex: 5,
            child: QRView(
              key: qrKey,
              onQRViewCreated: _onQRViewCreated,
            ),
          ),
          Expanded(
            flex: 1,
            child: Center(
              child: (result != null)
                  ? Text(
                      'Barcode Type: ${describeEnum(result!.format)}   Data: ${result!.code}')
                  : Text('Scan a code'),
            ),
          )
        ],
      ),
    );
  }

  void _onQRViewCreated(QRViewController controller) {
    this.controller = controller;
    controller.scannedDataStream.listen((scanData) {
      setState(() {
        result = scanData;
      });
    });
  }

QRView 위젯안에 아래와 같이 controller를 넣어주는 형식의 예제코드를 사용해주면 카메라를 이용할 수 있다.

물론 해당 화면을 실행하기전에 카메라 권한을 체크하고 부여받아야한다.

권한을 부여하는 코드는 이 글을 참고하시기 바랍니다.  https://bangu4.tistory.com/348

 

결과 화면

커스텀 된 저의 개발 예시 화면일뿐입니다

 

아래 예제 코드에서는 더 많은 기능을 다루는 방법에 대한 예제코드를 볼 수 있다.

카메라 멈춤 / 재개 

 Row(
                    mainAxisAlignment: MainAxisAlignment.center,
                    crossAxisAlignment: CrossAxisAlignment.center,
                    children: <Widget>[
                      Container(
                        margin: const EdgeInsets.all(8),
                        child: ElevatedButton(
                          onPressed: () async {
                            await controller?.pauseCamera();
                          },
                          child: const Text('pause',
                              style: TextStyle(fontSize: 20)),
                        ),
                      ),
                      Container(
                        margin: const EdgeInsets.all(8),
                        child: ElevatedButton(
                          onPressed: () async {
                            await controller?.resumeCamera();
                          },
                          child: const Text('resume',
                              style: TextStyle(fontSize: 20)),
                        ),
                      )
                    ],
                  ),

 

화면 전환, 플래시 사용여부 

Row(
                    mainAxisAlignment: MainAxisAlignment.center,
                    crossAxisAlignment: CrossAxisAlignment.center,
                    children: <Widget>[
                      Container(
                        margin: const EdgeInsets.all(8),
                        child: ElevatedButton(
                            onPressed: () async {
                              await controller?.toggleFlash();
                              setState(() {});
                            },
                            child: FutureBuilder(
                              future: controller?.getFlashStatus(),
                              builder: (context, snapshot) {
                                return Text('Flash: ${snapshot.data}');
                              },
                            )),
                      ),
                      Container(
                        margin: const EdgeInsets.all(8),
                        child: ElevatedButton(
                            onPressed: () async {
                              await controller?.flipCamera();
                              setState(() {});
                            },
                            child: FutureBuilder(
                              future: controller?.getCameraInfo(),
                              builder: (context, snapshot) {
                                if (snapshot.data != null) {
                                  return Text(
                                      'Camera facing ${describeEnum(snapshot.data!)}');
                                } else {
                                  return const Text('loading');
                                }
                              },
                            )),
                      )
                    ],
                  ),

 

QR 결과값 다루기

 if (result != null)
                    Text(
                        'Barcode Type: ${describeEnum(result!.format)}   Data: ${result!.code}')
                  else
                    const Text('Scan a code'),
                  Row(
                    mainAxisAlignment: MainAxisAlignment.center,
                    crossAxisAlignment: CrossAxisAlignment.center,
                    children: <Widget>[
                      Container(
                        margin: const EdgeInsets.all(8),
                        child: ElevatedButton(
                            onPressed: () async {
                              await controller?.toggleFlash();
                              setState(() {});
                            },
                            child: FutureBuilder(
                              future: controller?.getFlashStatus(),
                              builder: (context, snapshot) {
                                return Text('Flash: ${snapshot.data}');
                              },
                            )),
                      ),

해당 예제코드에서 보이듯이 스캐너 controller가 가져온

result 결과값에 json형식으로 들어온 데이터를 확인하고 다룰 수 있습니다.

 

예제 화면 전제코드

import 'dart:developer';
import 'dart:io';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:qr_code_scanner/qr_code_scanner.dart';

void main() => runApp(const MaterialApp(home: MyHome()));

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Flutter Demo Home Page')),
      body: Center(
        child: ElevatedButton(
          onPressed: () {
            Navigator.of(context).push(MaterialPageRoute(
              builder: (context) => const QRViewExample(),
            ));
          },
          child: const Text('qrView'),
        ),
      ),
    );
  }
}

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

  @override
  State<StatefulWidget> createState() => _QRViewExampleState();
}

class _QRViewExampleState extends State<QRViewExample> {
  Barcode? result;
  QRViewController? controller;
  final GlobalKey qrKey = GlobalKey(debugLabel: 'QR');

  // In order to get hot reload to work we need to pause the camera if the platform
  // is android, or resume the camera if the platform is iOS.
  @override
  void reassemble() {
    super.reassemble();
    if (Platform.isAndroid) {
      controller!.pauseCamera();
    }
    controller!.resumeCamera();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: <Widget>[
          Expanded(flex: 4, child: _buildQrView(context)),
          Expanded(
            flex: 1,
            child: FittedBox(
              fit: BoxFit.contain,
              child: Column(
                mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                children: <Widget>[
                  if (result != null)
                    Text(
                        'Barcode Type: ${describeEnum(result!.format)}   Data: ${result!.code}')
                  else
                    const Text('Scan a code'),
                  Row(
                    mainAxisAlignment: MainAxisAlignment.center,
                    crossAxisAlignment: CrossAxisAlignment.center,
                    children: <Widget>[
                      Container(
                        margin: const EdgeInsets.all(8),
                        child: ElevatedButton(
                            onPressed: () async {
                              await controller?.toggleFlash();
                              setState(() {});
                            },
                            child: FutureBuilder(
                              future: controller?.getFlashStatus(),
                              builder: (context, snapshot) {
                                return Text('Flash: ${snapshot.data}');
                              },
                            )),
                      ),
                      Container(
                        margin: const EdgeInsets.all(8),
                        child: ElevatedButton(
                            onPressed: () async {
                              await controller?.flipCamera();
                              setState(() {});
                            },
                            child: FutureBuilder(
                              future: controller?.getCameraInfo(),
                              builder: (context, snapshot) {
                                if (snapshot.data != null) {
                                  return Text(
                                      'Camera facing ${describeEnum(snapshot.data!)}');
                                } else {
                                  return const Text('loading');
                                }
                              },
                            )),
                      )
                    ],
                  ),
                  Row(
                    mainAxisAlignment: MainAxisAlignment.center,
                    crossAxisAlignment: CrossAxisAlignment.center,
                    children: <Widget>[
                      Container(
                        margin: const EdgeInsets.all(8),
                        child: ElevatedButton(
                          onPressed: () async {
                            await controller?.pauseCamera();
                          },
                          child: const Text('pause',
                              style: TextStyle(fontSize: 20)),
                        ),
                      ),
                      Container(
                        margin: const EdgeInsets.all(8),
                        child: ElevatedButton(
                          onPressed: () async {
                            await controller?.resumeCamera();
                          },
                          child: const Text('resume',
                              style: TextStyle(fontSize: 20)),
                        ),
                      )
                    ],
                  ),
                ],
              ),
            ),
          )
        ],
      ),
    );
  }

  Widget _buildQrView(BuildContext context) {
    // For this example we check how width or tall the device is and change the scanArea and overlay accordingly.
    var scanArea = (MediaQuery.of(context).size.width < 400 ||
            MediaQuery.of(context).size.height < 400)
        ? 150.0
        : 300.0;
    // To ensure the Scanner view is properly sizes after rotation
    // we need to listen for Flutter SizeChanged notification and update controller
    return QRView(
      key: qrKey,
      onQRViewCreated: _onQRViewCreated,
      overlay: QrScannerOverlayShape(
          borderColor: Colors.red,
          borderRadius: 10,
          borderLength: 30,
          borderWidth: 10,
          cutOutSize: scanArea),
      onPermissionSet: (ctrl, p) => _onPermissionSet(context, ctrl, p),
    );
  }

  void _onQRViewCreated(QRViewController controller) {
    setState(() {
      this.controller = controller;
    });
    controller.scannedDataStream.listen((scanData) {
      setState(() {
        result = scanData;
      });
    });
  }

  void _onPermissionSet(BuildContext context, QRViewController ctrl, bool p) {
    log('${DateTime.now().toIso8601String()}_onPermissionSet $p');
    if (!p) {
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('no Permission')),
      );
    }
  }

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

 

 

https://pub.dev/packages/qr_code_scanner

qr_code_scanner | Flutter Package