tract_flutter

tract_flutter

Flutter integration for tract: cross-platform neural network inference with no system dependencies for users or devs to install.

This package builds the shared tract_ffi Rust crate automatically (via cargokit) and bundles it with your app, then re-exports the full tract API.

import 'package:tract_flutter/tract_flutter.dart';

await TractFlutter.ensureInitialized();
final model = await TractFlutter.loadOnnxAsset('assets/mobilenet.onnx',
    inputShape: [1, 3, 224, 224]);
final outputs = model.run([Tensor.float32(pixels, [1, 3, 224, 224])]);
model.dispose();

The native crate wraps the Rust tract engine, which is pure Rust, so it cross-compiles to Android, iOS, macOS, Windows and Linux without extra toolchains. Web is not supported (no dart:ffi).

Building requires Rust (rustup). To remove even that for consumers, the repo is set up for cargokit precompiled binaries:

• native/tract_ffi/cargokit.yaml holds the public signing key and the release URL prefix.
• .github/workflows/precompile.yml builds and uploads signed binaries to precompiled_<crate-hash> releases on tag pushes. It needs a CARGOKIT_PRIVATE_KEY repository secret: the hex private key printed by dart run build_tool gen-key (keep it secret; never commit it).

Once a release exists, consuming builds download the matching signed binary instead of invoking cargo; with none present, cargokit builds from source.