如何从flutter PDF包生成PDF时分页

import 'package:flutter/material.dart';
import 'package:pdf/widgets.dart' as pw;
import 'package:pdf/pdf.dart';
import 'package:path_provider/path_provider.dart';
import 'dart:io';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text('PDF Generator')),
        body: Center(child: GeneratePDFButton()),
      ),
    );
  }
}

class GeneratePDFButton extends StatelessWidget {
  Future<void> generatePdf() async {
    final pdf = pw.Document();

    pdf.addPage(
      pw.Page(
        build: (pw.Context context) => pw.Center(
          child: pw.Text('Hello World'),
        ),
      ),
    );

    pdf.addPage(
      pw.Page(
        build: (pw.Context context) => pw.Center(
          child: pw.Text('Another Page'),
        ),
      ),
    );

    final output = await getTemporaryDirectory();
    final file = File("${output.path}/example.pdf");
    await file.writeAsBytes(await pdf.save());
  }

  @override
  Widget build(BuildContext context) {
    return ElevatedButton(
      onPressed: generatePdf,
      child: Text('Generate PDF'),
    );
  }
}