AnkiDroid-Backend

Adapter allowing AnkiDroid to leverage Anki Desktop's Rust-based business logic layer via access to anki/rslib over JNI.

Why?

• Removes the need to port Anki Desktop's business logic to Java
  • 100% compatibility and no bugs
  • Rust should provide a speed increase
  • An upgrade for AnkiDroid should only require moving to a later commit in a submodule
  • Saves massive amount of AnkiDroid developer time & effort
  • Allows Anki Desktop to iterate faster
  • We can quickly port changes upstream, which will benefit the ecosystem
• Insulates Anki-Android users from the complexity of installing multiple toolchains
  • The Rust/Python/cross-compilation toolchain is much more complex than downloading Android Studio
  • A separate repository means we keep a low barrier to entry for new contributors

How to use it in a project

    implementation "io.github.david-allison-1:anki-android-backend:0.1.10"
    testImplementation "io.github.david-allison-1:anki-android-backend-testing:0.1.10"

Folders

/anki/ - git submodule containing the Anki Rust Codebase, used both for building into .so files, and to obtain the current .proto files for use in Java codegen

/tools/ Tools to generate efficient protobuf-based RPC calls using JNI

/rsdroid/ - Java library to be consumed by Anki-Android.

rsdroid-testing - Builds a testing library which exposes a function to load rsdroid in a non-Android context for testing via Robolectric

rsdroid-instrumented - Android Instrumented Test

This is defined as an application to allow instrumented tests to be run against a library - there may be a better method

/rslib-bridge/ (Rust) Android-specific library to communicate with anki/rslib

Implementation

• Points to a fixed commit of anki
  • Currently as a fork in david-allison-1/anki
  • Modified to use a submodule for translations so we have a reproducible build
  • Modifications to the library so we do not need to update to database schema 15 for version 1
• References backend.proto and fluent.proto which define RPC service calls to the anki backend
• Python script to auto-generate the Java interface/backend to the RPC mechanism. Invoked via gradle.
• Android Library which contains the rust based .so under (x86, x86-64, arm, arm64)
  • Implements android.database.sqlite, redirecting SQL to the rust library
  • Exposes RPC calls to Rust via a clean Java interface (net.ankiweb.rsdroid.RustBackend)
• Testing library to allow the above to be usable under Robolectric

Additional Information

See /docs for more in-depth information.

License

GPL-3.0 License
AGPL-3.0 Licence (anki submodule)