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Setup

Dependencies​

To start developing your Dart/Flutter library, you will need to download some dependencies locally.

Required​

The rest of this guide assumes you have the following tools installed on any development machines:

  • Flutter
  • rustup
  • Melos (needed for our monorepo, see here)
    • dart pub global activate melos to install once Dart/Flutter are installed

Optional​

If you would like to build your binaries (for Flutter devices) locally in addition to CI (say, to test on a real device or emulator), you will additionally need the following:

  • To compile to macOS/iOS targets
    • macOS
  • To cross-compile to Android targets
    • Android NDK
      • Most NDK versions should work nowadays due to fixes in cargo-ndk
        • Previously, NDK version 21 (r21e) was the only one that could be used easily
          • You might see reference to this elsewhere, but that is largely out of date
        • NDK version 25 (r25b) was working at the time of writing this documentation
  • To cross-compile to Windows/Linux targets
    • Zig
    • llvm (with clang-cl!)
      • Need to run brew install llvm on macOS since Apple's llvm doesn't have it

Repository Structure​

We will be using the following structure for our repository, assuming our library name is library_name:

  • .github/ for CI/CD (with GitHub Actions) & dependabot
  • packages/ where our Flutter/Dart packages will live
    • library_name/ the Dart-only (library) package using flutter_rust_bridge (FRB)
      • native/ the Rust library used by Dart
      • test/ unit tests for our Dart-only library
      • example/ an example project showing how to use library_name from Dart-only
        • test/ (optional) tests for the example; can be used to ensure example continues to work in CI
    • flutter_library_name/ the Flutter (library) package wrapping around library_name for ease of use
      • android/, ios/, linux/, macos/, & windows/ for platform-specific wrappers in order to bundle our library binaries with Flutter applications
      • test/ unit tests for our Flutter library (note: there might not be any if your Flutter library does not add any Flutter-specific functionality; in that case, add a dummy test in so CI is happy)
      • example/ an example project showing how to use flutter_library_name from within a Flutter application
        • integration_test/ integration tests to ensure your Flutter library, example, and platform-specific configuration are all working together correctly
  • scripts/ build Flutter binaries and handle release creation
  • platform-build/ the output (build) folder for all created Flutter binaries
  • analysis_options.yaml to enable consistent Dart analysis in our Dart/Flutter libraries
  • Cargo.toml so IDEs can find our Rust project under packages/library_name/native
  • melos.yaml to configure the monorepo, see more here