flutter_zxing/example/lib/pages/creator_page.dart

import 'dart:io';
import 'dart:typed_data';

import 'package:flutter/material.dart';
import 'package:flutter_zxing/flutter_zxing.dart';
import 'package:path_provider/path_provider.dart';
import 'package:share_plus/share_plus.dart';

late Directory tempDir;
String get tempPath => '${tempDir.path}/zxing.jpg';

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

  @override
  State<CreatorPage> createState() => _CreatorPageState();
}

class _CreatorPageState extends State<CreatorPage> {
  bool isAndroid() => Theme.of(context).platform == TargetPlatform.android;

  // Write result
  Uint8List? writeResult;

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

    initStateAsync();
  }

  void initStateAsync() async {
    getTemporaryDirectory().then((value) {
      tempDir = value;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Creator'),
      ),
      body: SingleChildScrollView(
        child: Column(
          children: [
            ZxingWriterWidget(
              onSuccess: (result) {
                setState(() {
                  writeResult = result;
                });
              },
              onError: (error) {
                setState(() {
                  writeResult = null;
                });
                ScaffoldMessenger.of(context).hideCurrentSnackBar();
                ScaffoldMessenger.of(context).showSnackBar(
                  SnackBar(
                    content: Padding(
                      padding: const EdgeInsets.only(bottom: 30.0),
                      child: Text(
                        error,
                        textAlign: TextAlign.center,
                      ),
                    ),
                  ),
                );
              },
            ),
            if (writeResult != null) buildWriteResult(),
          ],
        ),
      ),
    );
  }

  Column buildWriteResult() {
    return Column(
      children: [
        // Barcode image
        Image.memory(writeResult ?? Uint8List(0)),
        // Share button
        ElevatedButton(
          onPressed: () {
            // Save image to device
            final file = File(tempPath);
            file.writeAsBytesSync(writeResult ?? Uint8List(0));
            final path = file.path;
            // Share image
            Share.shareFiles([path]);
          },
          child: const Text('Share'),
        ),
      ],
    );
  }
}