Run saveDocument() in an isolate

[patricknicolosi]

Use case

The saveDocument function takes a long time to execute for more complex documents, it would be convenient to find a way to execute this function in an Isolate.

Currently, it is not possible to pass PdfViewerController to an isolate to run saveDocument() separately

Currently code stucks to show loading in showLoadingDialog.

import 'dart:io';
import 'package:flutter/material.dart';
import 'package:gym_manager_document_filler/helpers/ftp_helper.dart';
import 'package:gym_manager_document_filler/screens/home/home_screen.dart';
import 'package:gym_manager_document_filler/utils/assets_utils.dart';
import 'package:gym_manager_document_filler/utils/ui_utils.dart';
import 'package:lucide_icons_flutter/lucide_icons.dart';
import 'package:path_provider/path_provider.dart';
import 'package:syncfusion_flutter_pdfviewer/pdfviewer.dart';

class PdfViewer extends StatelessWidget {
  final String documentAssetPath;
  PdfViewer(this.documentAssetPath, {super.key});

  final PdfViewerController _pdfViewerController = PdfViewerController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      floatingActionButton: FloatingActionButton.extended(
          icon: const Icon(LucideIcons.save),
          label: const Text("Salva"),
          onPressed: () async {
            await _exportPdf(
                context: context,
                fileName: AssetsUtils.formatAssetsName(
                    documentAssetPath.split('/')[2]));
          }),
      body: SafeArea(
        child: Stack(
          children: [
            SfPdfViewer.asset(
              documentAssetPath,
              controller: _pdfViewerController,
              canShowPageLoadingIndicator: true,
              initialZoomLevel: 0.6,
            ),
            Padding(
              padding: const EdgeInsets.all(50),
              child: IconButton.filledTonal(
                  icon: const Icon(LucideIcons.chevronLeft),
                  onPressed: () {
                    Navigator.pop(context);
                  }),
            )
          ],
        ),
      ),
    );
  }

  Future _exportPdf(
      {required BuildContext context, required String fileName}) async {
    UiUtils.showLoadingDialog(context: context);
    await Future.delayed(const Duration(seconds: 1));
    try {
      File filledPdf = await _createPdfFile(fileName: fileName);
      await FtpHelper.getIstance()
          .upload(fileName: "$fileName.pdf", file: filledPdf);
      filledPdf.deleteSync();
      _showSuccessUpload(context);
    } catch (e) {
      Navigator.pop(context);
      _showErrorUpload(context, e);
      return;
    }
  }

  Future<File> _createPdfFile({required String fileName}) async {
    try {
      Directory dir = await getApplicationSupportDirectory();
      File filledPdf = File("${dir.path}/$fileName.pdf");
      filledPdf.writeAsBytesSync(await _pdfViewerController.saveDocument());
      return filledPdf;
    } catch (e) {
      throw Exception(e);
    }
  }

  void _showErrorUpload(BuildContext context, Object e) {
    ScaffoldMessenger.of(context).showSnackBar(SnackBar(
      backgroundColor: Colors.red,
      content: Text(
        e.toString(),
        style: const TextStyle(color: Colors.white),
      ),
      behavior: SnackBarBehavior.floating,
      margin: const EdgeInsets.all(10),
      shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(8)),
    ));
    Navigator.of(context).pushAndRemoveUntil(
        MaterialPageRoute(builder: (context) => const HomeScreen()),
        (Route<dynamic> route) => false);
  }

  void _showSuccessUpload(BuildContext context) {
    ScaffoldMessenger.of(context).showSnackBar(SnackBar(
      backgroundColor: Colors.green,
      content: const Text(
        "Modulo salvato con successo",
        style: TextStyle(color: Colors.white),
      ),
      behavior: SnackBarBehavior.floating,
      margin: const EdgeInsets.all(10),
      shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(8)),
    ));
    Navigator.of(context).pushAndRemoveUntil(
        MaterialPageRoute(builder: (context) => const HomeScreen()),
        (Route<dynamic> route) => false);
  }
}