flutter_zxing 1.0.0-beta.6

A barcode scanner and generator natively in Flutter with Dart FFI based on ZXing.

example/lib/main.dart

import 'dart:ui';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter_zxing/flutter_zxing.dart';
import 'package:image_picker/image_picker.dart';

void main() {
  zx.setLogEnabled(false);
  runApp(const MyApp());
}

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

  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      title: 'Flutter Zxing Example',
      home: DemoPage(),
    );
  }
}

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

  @override
  State<DemoPage> createState() => _DemoPageState();
}

class _DemoPageState extends State<DemoPage> {
  Uint8List? createdCodeBytes;

  Code? result;
  List<Code> multiResult = [];

  bool showDebugInfo = true;
  int successScans = 0;
  int failedScans = 0;

  @override
  Widget build(BuildContext context) {
    final isCameraSupported = defaultTargetPlatform == TargetPlatform.iOS ||
        defaultTargetPlatform == TargetPlatform.android;
    return DefaultTabController(
      length: 2,
      child: Scaffold(
        appBar: AppBar(
          title: const Text('Flutter Zxing Example'),
          bottom: const TabBar(
            tabs: [
              Tab(text: 'Scan Code'),
              Tab(text: 'Create Code'),
            ],
          ),
        ),
        body: TabBarView(
          physics: const NeverScrollableScrollPhysics(),
          children: [
            if (kIsWeb)
              const UnsupportedPlatformWidget()
            else if (!isCameraSupported)
              const Center(
                child: Text('Camera not supported on this platform'),
              )
            else if (result != null && result?.isValid == true)
              ScanResultWidget(
                result: result,
                onScanAgain: () => setState(() => result = null),
              )
            else
              Stack(
                children: [
                  ReaderWidget(
                    onScan: _onScanSuccess,
                    onScanFailure: _onScanFailure,
                    onMultiScan: _onMultiScanSuccess,
                    onMultiScanFailure: _onMultiScanFailure,
                    isMultiScan: true,
                    // showScannerOverlay: false,
                    // scanDelay: const Duration(milliseconds: 0),
                    // tryInverted: true,
                  ),
                  // show multi results as rectangles
                  // if (multiResult.isNotEmpty)
                  //   Positioned.fill(
                  //     child: CustomPaint(
                  //       painter: MultiScanPainter(
                  //         codes: multiResult,
                  //         size: Size(
                  //           MediaQuery.of(context).size.width,
                  //           MediaQuery.of(context).size.height,
                  //         ),
                  //       ),
                  //     ),
                  //   ),
                  ScanFromGalleryWidget(
                    onScan: _onScanSuccess,
                    onScanFailure: _onScanFailure,
                  ),
                  if (showDebugInfo)
                    DebugInfoWidget(
                      successScans: successScans,
                      failedScans: failedScans,
                      error: result?.error,
                      duration: result?.duration ?? 0,
                      onReset: _onReset,
                    ),
                ],
              ),
            if (kIsWeb)
              const UnsupportedPlatformWidget()
            else
              ListView(
                children: [
                  WriterWidget(
                    messages: const Messages(
                      createButton: 'Create Code',
                    ),
                    onSuccess: (result, bytes) {
                      setState(() {
                        createdCodeBytes = bytes;
                      });
                    },
                    onError: (error) {
                      _showMessage(context, 'Error: $error');
                    },
                  ),
                  if (createdCodeBytes != null)
                    Image.memory(createdCodeBytes ?? Uint8List(0), height: 200),
                ],
              ),
          ],
        ),
      ),
    );
  }

  _onScanSuccess(Code? code) {
    setState(() {
      successScans++;
      result = code;
    });
  }

  _onScanFailure(Code? code) {
    setState(() {
      failedScans++;
      result = code;
    });
    if (code?.error?.isNotEmpty == true) {
      _showMessage(context, 'Error: ${code?.error}');
    }
  }

  _onMultiScanSuccess(List<Code> codes) {
    setState(() {
      successScans++;
      multiResult = codes;
    });
  }

  _onMultiScanFailure(List<Code> codes) {
    setState(() {
      failedScans++;
      multiResult = codes;
    });
    if (result?.error?.isNotEmpty == true) {
      _showMessage(context, 'Error: ${codes.first.error}');
    }
  }

  _showMessage(BuildContext context, String message) {
    ScaffoldMessenger.of(context).hideCurrentSnackBar();
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(content: Text(message)),
    );
  }

  _onReset() {
    setState(() {
      successScans = 0;
      failedScans = 0;
    });
  }
}

class ScanResultWidget extends StatelessWidget {
  const ScanResultWidget({
    Key? key,
    this.result,
    this.onScanAgain,
  }) : super(key: key);

  final Code? result;
  final Function()? onScanAgain;

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Padding(
        padding: const EdgeInsets.all(20.0),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(
              result?.format?.name ?? '',
              style: Theme.of(context).textTheme.headline5,
            ),
            const SizedBox(height: 20),
            Text(
              result?.text ?? '',
              style: Theme.of(context).textTheme.headline6,
            ),
            const SizedBox(height: 20),
            Text(
              'Inverted: ${result?.isInverted}\t\tMirrored: ${result?.isMirrored}',
              style: Theme.of(context).textTheme.bodyText2,
            ),
            const SizedBox(height: 40),
            ElevatedButton(
              onPressed: onScanAgain,
              child: const Text('Scan Again'),
            ),
          ],
        ),
      ),
    );
  }
}

class ScanFromGalleryWidget extends StatelessWidget {
  const ScanFromGalleryWidget({
    Key? key,
    this.onScan,
    this.onScanFailure,
  }) : super(key: key);

  final Function(Code)? onScan;
  final Function(Code?)? onScanFailure;

  @override
  Widget build(BuildContext context) {
    return Positioned(
      bottom: 20,
      right: 20,
      child: FloatingActionButton(
        onPressed: _onFromGalleryButtonTapped,
        child: const Icon(Icons.image),
      ),
    );
  }

  void _onFromGalleryButtonTapped() async {
    final XFile? file =
        await ImagePicker().pickImage(source: ImageSource.gallery);
    if (file != null) {
      final Code? result = await zx.readBarcodeImagePath(
        file,
        params: DecodeParams(tryInverted: true),
      );
      if (result != null && result.isValid) {
        onScan?.call(result);
      } else {
        result?.error = 'No barcode found';
        onScanFailure?.call(result);
      }
    }
  }
}

class DebugInfoWidget extends StatelessWidget {
  const DebugInfoWidget({
    Key? key,
    required this.successScans,
    required this.failedScans,
    this.error,
    this.duration = 0,
    this.onReset,
  }) : super(key: key);

  final int successScans;
  final int failedScans;
  final String? error;
  final int duration;

  final Function()? onReset;

  @override
  Widget build(BuildContext context) {
    return Align(
      alignment: Alignment.topLeft,
      child: Padding(
        padding: const EdgeInsets.all(8.0),
        child: ClipRRect(
          borderRadius: BorderRadius.circular(10),
          child: Container(
            color: Colors.white.withOpacity(0.7),
            padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 5),
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: [
                Text(
                  'Success: $successScans\nFailed: $failedScans\nDuration: $duration ms',
                  style: Theme.of(context).textTheme.bodySmall,
                ),
                TextButton(
                  onPressed: onReset,
                  child: const Text('Reset'),
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}

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

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Text(
        'This platform is not supported yet.',
        style: Theme.of(context).textTheme.headline6,
      ),
    );
  }
}

class MultiResultWidget extends StatelessWidget {
  const MultiResultWidget({
    super.key,
    this.results = const [],
  });

  final List<Code> results;

  @override
  Widget build(BuildContext context) {
    return Container();
  }
}

class MultiScanPainter extends CustomPainter {
  MultiScanPainter({
    required this.codes,
    required this.size,
    // required this.scale,
    // required this.offset,
  });

  final List<Code> codes;
  final Size size;
  final double scale = 1;
  final Offset offset = Offset.zero;

  @override
  void paint(Canvas canvas, Size size) {
    final Paint paint = Paint()
      ..color = Colors.green
      ..strokeWidth = 2
      ..style = PaintingStyle.stroke;

    for (final Code code in codes) {
      final position = code.position;
      if (position == null) {
        continue;
      }
      // position to points
      final List<Offset> points = positionToPoints(position);
      // debugPrint('w: ${position.imageWidth} h: ${position.imageHeight}');
      // print(points);
      canvas.drawPoints(PointMode.polygon, points, paint);
    }
  }

  @override
  bool shouldRepaint(MultiScanPainter oldDelegate) {
    return true;
  }

  List<Offset> positionToPoints(Position pos) {
    return [
      Offset(pos.topLeftX.toDouble(), pos.topLeftY.toDouble()),
      Offset(pos.topRightX.toDouble(), pos.topRightY.toDouble()),
      Offset(pos.bottomRightX.toDouble(), pos.bottomRightY.toDouble()),
      Offset(pos.bottomLeftX.toDouble(), pos.bottomLeftY.toDouble()),
    ];
  }
}