koni_jxl_flutter 0.1.0

Flutter bindings for koni_jxl: display and encode JPEG XL (.jxl) images with a pure Dart codec — no native dependencies, all platforms.

koni_jxl_flutter

Display and encode JPEG XL (.jxl) images in Flutter with a pure Dart codec — no native libraries, no FFI, no platform channels. Works on Android, iOS, macOS, Windows and Linux out of the box (and on the web, with reduced lossy-decode speed).

import 'package:koni_jxl_flutter/koni_jxl_flutter.dart';

// Like any other ImageProvider:
Image(image: JxlImageProvider.asset('assets/page.jxl'))
Image(image: JxlImageProvider.file(File('/comics/page-042.jxl')))
Image(image: JxlImageProvider.memory(jxlBytes))

// Or decode to a ui.Image directly:
final ui.Image image = await decodeJxlToUiImage(bytes);

Decoding runs in a background isolate (Isolate.run) so the UI thread never blocks; decoded images participate in Flutter's ImageCache normally.

What's included

• JxlImageProvider (.asset / .file / .memory) and decodeJxlToUiImage — decode a still image.
• JxlAnimationView and decodeJxlAnimation — play animated JPEG XL with correct per-frame timing and loop count.
• JxlProgressiveImage and decodeJxlProgressive — show a blurry 1:8 preview while bytes stream in (e.g. from the network), then swap in the sharp final image.
• encodeJxlFromRgba / encodeJxlFromUiImage — lossless JPEG XL encoding in a background isolate.

Full lossless (bit-exact) and lossy (VarDCT) decoding, animation, splines and streaming come from the underlying koni_jxl package. Unsupported files throw JxlUnsupportedException with a stable feature id, so you can fall back to another pipeline per file.

See the example/ app for a small gallery.

License

MIT — see LICENSE and NOTICE.