Rust on Android

Libraries and tools for Rust programming on Android targets:

Name	Description	Badges
ndk-sys	Raw FFI bindings to the NDK
ndk	Safe abstraction of the bindings
ndk-glue	Startup code
ndk-build	Everything for building apk's
cargo-apk	Build tool

See ndk-examples for examples using the NDK and the README files of the crates for more details.

Hello world

Quick start for setting up a new project with support for Android. For communication with the Android framework in our native Rust application we require a NativeActivity. ndk-glue will do the necessary initialization when calling main but requires a few adjustments:

Cargo.toml

[lib]
crate-type = ["lib", "cdylib"]

Wraps main function using attribute macro ndk::glue::main:

src/lib.rs

#[cfg_attr(target_os = "android", ndk_glue::main(backtrace = "on"))]
pub fn main() {
    println!("hello world");
}

src/main.rs

fn main() {
    $crate::main();
}

Install cargo apk for building, running and debugging your application:

cargo install cargo-apk

We can now directly execute our Hello World application on a real connected device or an emulator:

cargo apk run

Logging and stdout

Stdout is redirected to the android log api when using ndk-glue. Any logger that logs to stdout, like println!, should therefore work.

Use can filter the output in logcat

adb logcat RustStdoutStderr:D *:S

Android logger

Android logger can be setup using feature "logger" and attribute macro like so:

src/lib.rs

#[cfg_attr(target_os = "android", ndk_glue::main(logger(level = "debug", tag = "my-tag")))]
pub fn main() {
    log!("hello world");
}

Overriding crate paths

The macro ndk_glue::main tries to determine crate names from current Cargo.toml. In cases when it is not possible the default crate names will be used. You can override this names with specific paths like so:

#[ndk_glue::main(
  ndk_glue = "path::to::ndk_glue",
  logger(android_logger = "path::to::android_logger",
         log = "path::to::log")
)]
fn main() {}

JNI

Java Native Interface (JNI) allows executing Java code in a VM from native applications. ndk-examples contains an jni_audio example which will print out all output audio devices in the log.

• jni, JNI bindings for Rust

Winit and glutin

TODO shameless plug

Flutter

TODO shameless plug