how to save image in local storage in flutter code example

Example: How to fetch pdfs from local storage in flutter

import 'dart:io';
import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter_file_manager/flutter_file_manager.dart';
import 'package:flutter_full_pdf_viewer/full_pdf_viewer_scaffold.dart';
import 'package:path_provider_ex/path_provider_ex.dart';
//import package files

void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return  MaterialApp(
          home: MyPDFList(), //call MyPDF List file
    );
  }
}

//apply this class on home: attribute at MaterialApp()
class MyPDFList extends StatefulWidget{
  @override
  State<StatefulWidget> createState() {
    return _MyPDFList(); //create state 
  }
}

class _MyPDFList extends State<MyPDFList>{
  var files;
 
  void getFiles() async { //asyn function to get list of files
      List<StorageInfo> storageInfo = await PathProviderEx.getStorageInfo();
      var root = storageInfo[0].rootDir; //storageInfo[1] for SD card, geting the root directory
      var fm = FileManager(root: Directory(root)); //
      files = await fm.filesTree( 
        excludedPaths: ["/storage/emulated/0/Android"],
        extensions: ["pdf"] //optional, to filter files, list only pdf files
      );
      setState(() {}); //update the UI
  }

  @override
  void initState() {
    getFiles(); //call getFiles() function on initial state. 
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title:Text("PDF File list from SD Card"),
        backgroundColor: Colors.redAccent
      ),
      body:files == null? Text("Searching Files"):
           ListView.builder(  //if file/folder list is grabbed, then show here
              itemCount: files?.length ?? 0,
              itemBuilder: (context, index) {
                    return Card(
                      child:ListTile(
                         title: Text(files[index].path.split('/').last),
                         leading: Icon(Icons.picture_as_pdf),
                         trailing: Icon(Icons.arrow_forward, color: Colors.redAccent,),
                         onTap: (){
                           Navigator.push(context, MaterialPageRoute(builder: (context){
                             return ViewPDF(pathPDF:files[index].path.toString());
                             //open viewPDF page on click
                           }));
                         },
                      )
                    );
              },
          )
    );
  }
}

class ViewPDF extends StatelessWidget {
  String pathPDF = "";
  ViewPDF({this.pathPDF});

  @override
  Widget build(BuildContext context) {
    return PDFViewerScaffold( //view PDF 
        appBar: AppBar(
          title: Text("Document"),
          backgroundColor: Colors.deepOrangeAccent,
        ),
        path: pathPDF
    );
  }
}