flutter_libavif #

flutter_libavif supplies Flutter ImageProviders backed by the source-built native decoder in package:libavif.

Image(
  image: AvifAssetImage(
    'assets/cover.avif',
    cacheWidth: 1024,
  ),
)

Providers are available for asset, memory, file, and HTTP sources:

AvifAssetImage('assets/image.avif');
AvifMemoryImage(bytes);
AvifFileImage(File('/path/to/image.avif'));
AvifNetworkImage('https://example.com/image.avif');

Use Flutter's standard Image widget for layout, frame/error builders, filtering, opacity, and accessibility. cacheWidth and cacheHeight are part of each provider's cache key and are passed into native decode, avoiding a full-resolution RGBA allocation and copy for thumbnails. Decoder thread, dimension, pixel, and input-byte limits are configured with AvifDecodeOptions.

Memory-backed image work is cancelled when its last Flutter image-stream listener disappears. This keeps fast, recycled lists from retaining obsolete queued decodes.

All providers display animated AVIF through Flutter's standard Image widget. Frame timing and finite or infinite repetition come from the AVIF container. Frame scheduling pauses when the stream has no listeners, and native sequence resources are released when Flutter disposes the stream. Providers also begin native worker initialization while source bytes load, so startup work stays off the UI isolate and can overlap asset or network I/O. Sequence opening also prefetches frame zero in the same native job, avoiding a second worker-queue round trip before an image can be displayed.

Applications that already own transport and caching can subclass AvifImageProvider instead of surrendering those policies to the package:

final class CachedAvifImage extends AvifImageProvider<CachedAvifImage> {
  CachedAvifImage(this.url);

  final String url;

  @override
  Future<CachedAvifImage> obtainKey(ImageConfiguration configuration) async =>
      this;

  @override
  AvifImageSource loadAvifSource(CachedAvifImage key) => AvifImageSource(
    bytes: cacheOrDownload(key.url),
    chunkEvents: downloadProgress(key.url),
    cancel: () => cancelDownload(key.url),
  );
}

The source contract owns bytes, progress, and cancellation; the base provider owns decode limits, native scaling, animated frame scheduling, diagnostics, and disposal. The package imports native I/O providers and does not support Flutter web.