network_to_file_image

This is a mixture of FileImage and NetworkImage. It will download the image from the url once, save it locally in the file system, and then use it from there in the future.

In more detail:

Given a file and url of an image, it first tries to read it from the local file. It decodes the given File object as an image, associating it with the given scale.

However, if the image doesn't yet exist as a local file, it fetches the given URL from the network, associating it with the given scale, and then saves it to the local file. The image will be cached regardless of cache headers from the server.

Notes:

  • If the provided url is null or empty, NetworkToFileImage will default to FileImage. It will read the image from the local file, and won't try to download it from the network.

  • If the provided file is null, NetworkToFileImage will default to NetworkImage. It will download the image from the network, and won't save it locally.

Usage

Import the package

First, add network_to_file_image as a dependency in your pubspec.yaml

Then, import it:

import 'package:network_to_file_image/network_to_file_image.dart';

Use the package

If you also listed path_provider in your pubspec.yaml file:

path_provider: ^0.4.1

Then you can create a file from a file name:

Future<File> file(String filename) async {
  Directory dir = await getApplicationDocumentsDirectory();
  String pathName = p.join(dir.path, filename);
  return File(pathName);
}

var myFile = await file("myFileName.png"),

Then, create the image:

Image(image: NetworkToFileImage(url: "http://example.com/someFile.png", file: myFile))

If you make debug: true it prints to the console whether the image was read from the file or fetched from the network:

Image(image: NetworkToFileImage(url: "http://example.com/someFile.png", file: myFile, debug: true))    

Don't forget to check the example tab.

Tests

You can set mock files. Please see methods:

  • setMockFile(File file, Uint8List bytes)
  • setMockUrl(String url, Uint8List bytes)
  • clearMocks()
  • clearMockFiles()
  • clearMockUrls()

See also


Other Flutter packages I've authored:

Libraries

network_to_file_image