Integrating Rust + Flutter + Kotlin for Mobile Applications

With the introduction of ffi in Dart, things became more smoother now, with a better performance as the interction now is Dart/Rust directly, without a need for Dart/Kotlin/Rust or Dart/Swift/Rust cycle, below a simple example:

First src/lib.rs

#[no_mangle]pub extern fn rust_fn(x: i32) -> i32 {       println!("Hello from rust\nI'll return: {}", x.pow(2));    x.pow(2) }

and Cargo.toml

[package]name = "Double_in_Rost"version = "0.1.0"authors = ["Hasan Yousef"]edition = "2018"[lib]name = "rust_lib"crate-type = ["dylib"] # could be `staticlib` as well[dependencies]

Running cargo build --release will generate target\release\rust_lib.dll copy/paste it into Dart application root directory

Write Dart code as below:

import 'dart:ffi';import 'dart:io' show Platform;// FFI signature of the hello_world C functiontypedef ffi_func = Int32 Function(Int32 x);  //pub extern fn rust_fn(x: i32) -> i32// Dart type definition for calling the C foreign functiontypedef dart_func = int Function(int x);void main() {  // Open the dynamic library  var path = './rust_lib.so';  if (Platform.isMacOS) path = './rust_lib.dylib';  if (Platform.isWindows) path = 'rust_lib.dll';  final dylib = DynamicLibrary.open(path);  // Look up the Rust/C function  final my_func =      dylib.lookup<NativeFunction<ffi_func>>('rust_fn').asFunction<dart_func>();  print('Double of 3 is ${my_func(3)}');}