irondash_message_channel

Rust-dart桥接器，类似于Flutter的平台通道。

此包允许使用类似Flutter平台通道的模式从Dart调用Rust代码，反之亦然。

• 易于使用的便捷API（Dart端模仿平台通道API）。
• 高性能
  • 从Rust调用Dart时二进制数据无复制
  • 从Dart调用Rust时二进制数据精确复制一次
• Rust宏用于自动序列化和反序列化（类似于Serde但针对零复制进行了优化）
• 无需代码生成
• 线程亲和性 - Rust通道对应项绑定到创建通道的线程。只要运行RunLoop，就可以在平台线程或任何后台线程上拥有通道。
• 最终化处理器 - Rust端可以在Dart对象被垃圾回收时收到通知。
• 异步支持

用法

初始设置

因为Rust代码需要访问Dart FFI API，所以需要进行一些设置。

/// initialize context for Native library.
MessageChannelContext _initNativeContext() {
    final dylib = defaultTargetPlatform == TargetPlatform.android
        ? DynamicLibrary.open("libmyexample.so")
        : (defaultTargetPlatform == TargetPlatform.windows
            ? DynamicLibrary.open("myexample.dll")
            : DynamicLibrary.process());

    // This function will be called by MessageChannel with opaque FFI
    // initialization data. From it you should call
    // `irondash_init_message_channel_context` and do any other initialization,
    // i.e. register rust method channel handlers.
    final function =
        dylib.lookup<NativeFunction<MessageChannelContextInitFunction>>(
            "my_example_init_message_channel_context");
    return MessageChannelContext.forInitFunction(function);
}

final nativeContext = _initNativeContext();

// Now you can create method channels

final _channel =
    NativeMethodChannel('my_method_channel', context: nativeContext);

_channel.setMethodCallHandler(...);

Rust端

use irondash_message_channel::*;

#[no_mangle]
pub extern "C" fn my_example_init_message_channel_context(data: *mut c_void) -> FunctionResult {
    irondash_init_message_channel_context(data)
}

简单用法

设置完成后，您可以使用Dart NativeMethodChannel，类似于Flutter的PlatformChannel

final _channel = NativeMethodChannel('my_method_channel', context: nativeContext);

_channel.setMessageHandler((call) async {
    if (call.method == 'myMethod') {
        return 'myResult';
    }
    return null;
});

final res = await _channel.invokeMethod('someMethod', 'someArg');

在Rust端，您可以实现对非异步版本的MethodHandler trait，或者如果您想使用异步/await，可以使用AsyncMethodHandler

use irondash_message_channel::*;

struct MyHandler {}

impl MethodHandler for MyHandler {
    fn on_method_call(&self, call: MethodCall, reply: MethodCallReply) {
        match call.method.as_str() {
            "getMeaningOfUniverse" => {
                reply.send_ok(42);
            }
            _ => reply.send_error(
                "invalid_method".into(),
                Some(format!("Unknown Method: {}", call.method)),
                Value::Null,
            ),
        }
    }
}

fn init() {
    let handler = MyHandler {}.register("my_method_channel");
    // make sure handler is not dropped, otherwise it can't handle method calls.
}

use irondash_message_channel::*;

struct MyHandler {}

#[async_trait(?Send)]
impl AsyncMethodHandler for MyHandler {
    async fn on_method_call(&self, call: MethodCall) -> PlatformResult {
        match call.method.as_str() {
            "getMeaningOfUniverse" => {
                Ok(42.into())
            }
            _ => Err(PlatformError {
                code: "invalid_method".into(),
                message: Some(format!("Unknown Method: {}", call.method)),
                detail: Value::Null,
            })),
        }
    }
}

fn init() {
    let handler = MyHandler {}.register("my_method_channel");
    // make sure handler is not dropped, otherwise it can't handle method calls.
}

use irondash_message_channel::*;

struct MyHandler {
    invoker: Late<AsyncMethodInvoker>,
}

#[async_trait(?Send)]
impl AsyncMethodHandler for MyHandler {
    // This will be called right after method channel registration.
    // You can use invoker to call Dart methods handlers.
    fn assign_invoker(&self, invoker: AsyncMethodInvoker) {
        self.invoker.set(invoker);
    }

    // ...
}

impl MethodHandler for MyHandler {
    /// Called when isolate is about to be destroyed.
    fn on_isolate_destroyed(&self, _isolate: IsolateId) {}
    // ...

[dependencies]
irondash_message_channel = { version = "0.1.0", features = ["derive"] }

#[derive(TryFromValue, IntoValue)]
struct AdditionRequest {
    a: f64,
    b: f64,
}

#[derive(IntoValue)]
struct AdditionResponse {
    result: f64,
    request: AdditionRequest,
}

let value: Value = get_value_from_somewhere();
let request: AdditionRequest = value.try_into()?;
let response: Value = AdditionResponse {
    result: request.a + request.b,
    request,
}.into();

#[derive(IntoValue, TryFromValue)]
#[irondash(tag = "t", content = "c")]
#[irondash(rename_all = "UPPERCASE")]
enum Enum3CustomTagContent {
    Abc,
    #[irondash(rename = "_Def")]
    Def,
    SingleValue(i64),
    #[irondash(rename = "_DoubleValue")]
    DoubleValue(f64, f64),
    Xyz {
        x: i64,
        s: String,
        z1: Option<i64>,
        #[irondash(skip_if_empty)]
        z2: Option<i64>,
        z3: Option<f64>,
    },
}