How to store image to cachednetwrok image in flutter

Question

I have the following code where I fetch an image from firebase storage as an Image. Now, I want to store this image in my CachedNetworkImage so that I don't have to fetch it every time from the DB. Since the cache.networkimage expects a URL and I am fetching an Image, how do I use the cache.networkimage?

Here's my code;

  final FirebaseStorage storage = FirebaseStorage(
      app: Firestore.instance.app,
      storageBucket: 'gs://my-project.appspot.com');

  Uint8List imageBytes;
  String errorMsg;

  _MyHomePageState() {
      storage.ref().child('selfies/me2.jpg').getData(10000000).then((data) =>
                setState(() {
                  imageBytes = data;
                })
        ).catchError((e) =>
                setState(() {
                  errorMsg = e.error;
                })
        );
  }

  @override
  Widget build(BuildContext context) {
    var img = imageBytes != null ? Image.memory(
        imageBytes,
        fit: BoxFit.cover,
      ) : Text(errorMsg != null ? errorMsg : "Loading...");

    return new Scaffold(
        appBar: new AppBar(
          title: new Text(widget.title),
        ),
        body: new ListView(
          children: <Widget>[
            img,
          ],
        ));
  }
}```

Answer 1

Try this way out using firebase_image package. From here . You need to sync with image url (selfies/me2.jpg) and bucket url (gs://my-project.appspot.com)

Image(
        image: FirebaseImage('gs://bucket123/userIcon123.jpg'),
        // Works with standard parameters, e.g.
        fit: BoxFit.fitWidth,
        width: 100,
        // ... etc.
      )

Answer 2

Check out cached_network_image: ^2.5.0 package.

How to use it?

CachedNetworkImage(
        imageUrl: "http://via.placeholder.com/350x150",
        placeholder: (context, url) => CircularProgressIndicator(),
        errorWidget: (context, url, error) => Icon(Icons.error),
     ),

Answer 3

I'm not Fire-store user, but this should work.

It might needs a little modification or something, please share in a comment to update my answer according to that

You can get file object as follow..

import 'dart:io';
import 'dart:typed_data';

Uint8List readyData = imageBytes;
File('my_image.jpg').writeAsBytes(bodyBytes);

and save it using image_gallery_saver , so the code should look like

Future<String> _createFileFromString() async {
  final encodedStr = "...";
  Uint8List bytes = base64.decode(imageBytes);
  String dir = (await getApplicationDocumentsDirectory()).path;
  String fullPath = '$dir/abc.png';
  print("local file full path ${fullPath}");
  File file = File(fullPath);
  await file.writeAsBytes(bytes);
  print(file.path);

  final result = await ImageGallerySaver.saveImage(bytes);
  print(result);

  return file.path;
}

Answer 4

Cached network image and Flutter cache manager

The package Cached network image depends on another package called Flutter cache manager in order to store and retrieve image files.

Flutter cache manager

You need to download your image files and put them in the cache using the package. Here is an example code that gets files and their download urls from Firebase Storage and put them in the cache:

// import the flutter_cache_manager package
import 'package:flutter_cache_manager/flutter_cache_manager.dart';
// ... other imports

class MyCacheManager {
  Future<void> cacheImage() async {
    final FirebaseStorage storage = FirebaseStorage(
      app: Firestore.instance.app,
      storageBucket: 'gs://my-project.appspot.com',
    );

    final Reference ref = storage.ref().child('selfies/me2.jpg');
    
    // Get your image url
    final imageUrl = await ref.getDownloadURL();

    // Download your image data
    final imageBytes = await ref.getData(10000000);

    // Put the image file in the cache
    await DefaultCacheManager().putFile(
      imageUrl,
      imageBytes,
      fileExtension: "jpg",
    );
  }
}

Cached network image

Next, you will use CacheNetworkImage widget as it shown in the documentation .

// ... some code

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: CachedNetworkImage(
      imageUrl: "your_image_link_here",
      placeholder: (context, url) => CircularProgressIndicator(),
      errorWidget: (context, url, error) => Icon(Icons.error),
    ),
  );
}

If you put your image files in the cache by using Flutter cache manager, Cached network image should retrieve them from the cache directly. If your image files expire or the cache is cleared somehow, it will download and put them in the cache for you.

Full Example

import 'package:cached_network_image/cached_network_image.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_storage/firebase_storage.dart';
import 'package:flutter/material.dart';
import 'package:flutter_cache_manager/flutter_cache_manager.dart';

class MyCacheManager {
  final _storage = FirebaseStorage(
    app: FirebaseFirestore.instance.app,
    storageBucket: 'gs://my-project.appspot.com',
  );

  final defaultCacheManager = DefaultCacheManager();

  Future<String> cacheImage(String imagePath) async {
    final Reference ref = _storage.ref().child(imagePath);

    // Get your image url
    final imageUrl = await ref.getDownloadURL();

    // Check if the image file is not in the cache
    if ((await defaultCacheManager.getFileFromCache(imageUrl))?.file == null) {
      // Download your image data
      final imageBytes = await ref.getData(10000000);

      // Put the image file in the cache
      await defaultCacheManager.putFile(
        imageUrl,
        imageBytes,
        fileExtension: "jpg",
      );
    }

    // Return image download url
    return imageUrl;
  }
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  String _imageUrl;

  @override
  void initState() {
    final myCacheManager = MyCacheManager();

    // Image path from Firebase Storage
    var imagePath = 'selfies/me2.jpg';
    
    // This will try to find image in the cache first
    // If it can't find anything, it will download it from Firabase storage
    myCacheManager.cacheImage(imagePath).then((String imageUrl) {
      setState(() {
        // Get image url
        _imageUrl = imageUrl;
      });
    });

    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: _imageUrl != null
            ? CachedNetworkImage(
                imageUrl: _imageUrl,
                placeholder: (context, url) => CircularProgressIndicator(),
                errorWidget: (context, url, error) => Icon(Icons.error),
              )
            : CircularProgressIndicator(),
      ),
    );
  }
}

Answer 5

For your storage instance use some method like so

   Future<void> downloadURLExample() async {
      String downloadURL = await storage.ref('selfies/me2.jpg')
          .getDownloadURL();

  // Within your widgets:
  // CachedNetworkImage(imageUrl: downloadURL);
}

Answer 6

to get it working with Firebase Storage with included offline functionality I changed it that way

Future<String> cacheImage(String imagePath) async {
    
   var fileinfo = await defaultCacheManager.getFileFromCache(imagePath);
   if(fileinfo != null)
   {
     return fileinfo.file.path;
   } else{

      final Reference ref = _storage.child(imagePath);

      // Get your image url
      final imageUrl = await ref.getDownloadURL();

      // Check if the image file is not in the cache
      
        // Download your image data
        final imageBytes = await ref.getData(10000000);

        // Put the image file in the cache
      var file = await defaultCacheManager.putFile(
          imageUrl,
          imageBytes!,
          key: imagePath,);
        

        return file.path;
   }

    }

Answer 7

for anyone still stuck with this.. try this required no hacks and uses CachedNetworkImageProvider built-in retrieval methods.

first screen:

 CachedNetworkImage(
imageUrl: "https://whereismyimage.com",
 progressIndicatorBuilder:
(context, url, progress) {
 return CircularProgressIndicator(
value: progress.progress,
 );
},
errorWidget: (context, url, error) => const Icon(Icons.error),
),

then second screen

 Image(image: CachedNetworkImageProvider("https://whereismyimage.com)"),

The CachedNetworkImageProvider knows how to retrieve the cached image using the url.