Image Downloader

In this section, you will information on how to use and configure the Image Downloader in Beagle Flutter.


It handles how remote images will be downloaded and populated in BeagleImage widget by providing a class that implements this logic. Beagle Flutter provides a default implementation called DefaultBeagleImageDownloader. Here is the contract:

abstract class BeagleImageDownloader {
  Future<Uint8List> downloadImage(String url);

The downloadImage method takes as a parameter the image url and returns a Future<Uint8List> as the representation of the downloaded image.

Create a custom image downloader

To create your own image downloader, you need to implement the downloadImage method, see a simplified version of the default implementation:

class DefaultBeagleImageDownloader implements BeagleImageDownloader {
    @required this.httpClient,
  }) : assert(httpClient != null);

  final HttpClient httpClient;

  Future<Uint8List> downloadImage(String url) async {
    final request = BeagleRequest(url);
    final response = await httpClient.sendRequest(request);

    if (response.status != HttpStatus.ok) {
      throw Exception('HTTP request failed, statusCode: $response.status, $url');

    final bytes = response.bodyBytes;
    if (bytes.lengthInBytes == 0) {
      throw Exception('Image is an empty file: $url');

    return bytes;

Use a custom image downloader

To use your image downloader, pass it in the Beagle initialization method BeagleSdk.init just like the example below:

  imageDownloader: YourImageDownloader(),