Cached Images doesn't exists after App re-start

[Marc Andrew]

Hi all,

I'm trying to cache an image from the image_picker plugin with path_provider for later and offline use.

The image is saved in the getApplicationDocumentsDirectory() and I also save the image path in the shared preferences.

So that I can find the image again. The caching works as long I'm not stopping the App. 

If I stop the App and start it again, Flutter is saying the file doesn't exist.

I'm wondering how long the image is cached in the getApplicationDocumentsDirectory and why it is removed?

Is there a better way to cache/store the image to the device for later use?

I've seen a Youtube video by converting the image in base64 and save the converted image as String in the shared preferences.

Is this the best solution? 

Below you can see my code

import 'dart:io';
import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';
import 'package:path_provider/path_provider.dart';
import 'package:shared_preferences/shared_preferences.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  SharedPreferences prefs;

  File _image;
  File _memoryImage;

  Future _onPhotoLibraryTapped() async {
    // Image Picker plugin
    final File image = await ImagePicker.pickImage(
        source: ImageSource.gallery, imageQuality: 100);

    final Directory directory = await getApplicationDocumentsDirectory();
    // Copy the image into the new directory
    final File newImage = await image.copy('${directory.path}/profile_image.jpg');

    // Save the image path in shared preferences
    SharedPreferences prefs = await SharedPreferences.getInstance();
    prefs.setString('profile_image', newImage.path);

    // Print the image path
    print(newImage.path);

    setState(() {
      _image = newImage;
    });
  }

  Future _loadImageFromMemory() async {
    // Get the image path from shared preferences
    SharedPreferences prefs = await SharedPreferences.getInstance();
    String imagePath = prefs.getString('profile_image') ?? null;

    if(imagePath != null) {
      setState(() {
        _memoryImage = File(imagePath);
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
        actions: <Widget>[
          IconButton(
            icon: Icon(Icons.refresh),
            onPressed: () {
              _loadImageFromMemory();
            },
          ),
          IconButton(
            icon: Icon(Icons.add),
            onPressed: () {
              _onPhotoLibraryTapped();
            },
          ),
        ],
      ),
      body: Column(
        children: <Widget>[
          Container(
            child: _image == null ? Text('No image selected') : Image.file(_image),
          ),
          Container(
            child: _memoryImage == null ? Text('No image in the cache') : Image.file(_memoryImage),
          ),
        ],
      ),
    );
  }
}

Thank you and Happy New Year!

Marc

[Andy Greenshaw]

Don’t save the image path. On each app restart, the “root” directory of your app changes (for security reasons). Just save the name and rebuild the path using getApplicationDocumentsDirectory() each app start.

 

---

From: flutt...@googlegroups.com on behalf of Marc Andrew <marc4...@gmail.com>
Sent: Thursday, January 2, 2020 9:46 am
To: Flutter Development (flutter-dev)
Subject: Cached Images doesn't exists after App re-start

 

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[Marc Andrew]

Thank you Andy, I didn't know the "root" directory changes on each app restart.

Thanks,

Marc

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