如何在flutter中保存qrimage？

dependencies:
  qr_flutter: ^3.0.0

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

class QRImageScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('QR Image'),
      ),
      body: Center(
        child: QrImage(
          data: 'https://example.com',
          version: QrVersions.auto,
          size: 200.0,
          foregroundColor: Colors.black,
          backgroundColor: Colors.white,
        ),
      ),
    );
  }
}

import 'dart:typed_data';
import 'package:flutter/material.dart';
import 'package:qr_flutter/qr_flutter.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/services.dart';
import 'package:image_gallery_saver/image_gallery_saver.dart';

class QRImageScreen extends StatefulWidget {
  @override
  _QRImageScreenState createState() => _QRImageScreenState();
}

class _QRImageScreenState extends State<QRImageScreen> {
  GlobalKey globalKey = GlobalKey();

  Future<void> saveQRImage() async {
    try {
      RenderRepaintBoundary boundary =
          globalKey.currentContext.findRenderObject();
      var image = await boundary.toImage();
      ByteData byteData = await image.toByteData(format: ImageByteFormat.png);
      Uint8List pngBytes = byteData.buffer.asUint8List();
      await ImageGallerySaver.saveImage(pngBytes);
      showDialog(
        context: context,
        builder: (BuildContext context) {
          return AlertDialog(
            title: Text('QR Image Saved'),
            content: Text('The QR image has been saved to the gallery.'),
            actions: [
              FlatButton(
                child: Text('OK'),
                onPressed: () {
                  Navigator.of(context).pop();
                },
              ),
            ],
          );
        },
      );
    } catch (e) {
      showDialog(
        context: context,
        builder: (BuildContext context) {
          return AlertDialog(
            title: Text('Error'),
            content: Text('Failed to save the QR image.'),
            actions: [
              FlatButton(
                child: Text('OK'),
                onPressed: () {
                  Navigator.of(context).pop();
                },
              ),
            ],
          );
        },
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('QR Image'),
      ),
      body: Center(
        child: RepaintBoundary(
          key: globalKey,
          child: QrImage(
            data: 'https://example.com',
            version: QrVersions.auto,
            size: 200.0,
            foregroundColor: Colors.black,
            backgroundColor: Colors.white,
          ),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        child: Icon(Icons.save),
        onPressed: saveQRImage,
      ),
    );
  }
}

dependencies:
  image_gallery_saver: ^1.6.6