kmpdfkit_demo/lib/main.dart

import 'package:file_picker/file_picker.dart';
import 'package:flutter/material.dart';
import 'package:kmpdfkit_demo/compdfkit.dart';
import 'package:kmpdfkit_demo/widgets/page/pdf_page_widget.dart';
import 'package:kmpdfkit_demo/widgets/page/setting_page_widget.dart';
import 'package:kmpdfkit_demo/widgets/page_routes.dart';
import 'package:permission_handler/permission_handler.dart';

void main() {
  runApp(MaterialApp(
    home: const MyApp(),
    initialRoute: PageRoutes.home,
    routes: {
      PageRoutes.home: (context) => const MyApp(),
      PageRoutes.settings: (context) => const SettingPageWidget()
    },
  ));
}

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

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

class _MyAppState extends State<MyApp> {
  String _comPDFKitVersion = '';

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text(comPDFKitVersion()),
        ),
        body: Padding(
          padding: const EdgeInsets.all(8),
          child: Column(
            children: [
              Builder(
                  builder: (BuildContext context) => SizedBox(
                      width: double.infinity,
                      child: ElevatedButton(
                        onPressed: () {
                          showDocument(context);
                        },
                        child: const Text('Simple PDF Viewer'),
                      ))),
            ],
          ),
        ));
  }

  void initPlatformState() async {
    String? comPDFKitVersion = await ComPDFKit.getComPDFKitVersionCode();

    setState(() {
      _comPDFKitVersion = comPDFKitVersion ?? '';
    });
  }

  String comPDFKitVersion() {
    return 'ComPDFKit $_comPDFKitVersion';
  }

  ///request storage permission
  Future<bool> getPermission() async {
    var status = await Permission.storage.request();
    return status.isGranted;
  }

  Future<String?> getPDFFile() async {
    bool isGranted = await getPermission();
    if (!isGranted) {
      return null;
    }
    FilePickerResult? result = await FilePicker.platform.pickFiles(
        type: FileType.custom,
        allowedExtensions: ['pdf'],
        allowMultiple: false);
    if (result != null) {
      List<String?> files = result.paths;
      return files[0];
    } else {
      return null;
    }
  }

  void showDocument(BuildContext context) async {
    var documentPath = await getPDFFile();
    if (documentPath != null) {
      await Navigator.of(context).push<dynamic>(MaterialPageRoute<dynamic>(
          builder: (_) => PDFPageWidget(
                documentPath: documentPath,
              )));
    }
  }
}