"Native" subscribers for when you want to manage data by yourself

README.md

@@ -1,25 +1,23 @@
 R2R - Minimal ROS2 Rust bindings
 =============
 
-Minimal bindings for ROS2 that does *not* require hooking in to the ROS2 build infrastructure, in contrast to <https://github.com/ros2-rust/ros2_rust>. Message definitions are instead created by calling into the c introspection libraries to avoid the .msg/.idl pipeline.
+Minimal bindings for ROS2 that does *not* require hooking in to the ROS2 build infrastructure. If you want a more ROS-oriented approach, see <https://github.com/ros2-rust/ros2_rust>. In these bindings, convenience Rust types are created by calling into the c introspection libraries to circumvent the .msg/.idl pipeline. Another benefit of basing the code entirely on the exported shared libraries is that the native c types are still there when you need to trade convenience for performance. E.g. for looking into a large array of image data you can still get a pointer to the raw message.
 
 How to use
 ------------
-You need to source your ros installation before building/running. A couple of examples are included in examples/
+You need to source your ROS2 installation before building/running. A couple of examples are included in examples/
 ```
 . /opt/ros/dashing/setup.sh
 cargo build
 cargo run --example subscriber_with_thread
 ```
-
-In order to avoid building everything, put the message types you need in msgs.txt.
+In order to avoid building everything, put the message types you need in `msgs.txt` before building. (Or just `ros2 msg list > msgs.txt`).
 
 What works?
 --------
 - Only tested with ROS2 Dashing
 - Simple publish/subscribe, see examples.
 
-
 TODO
 ------------
 - The code generation is currently just a big hack. Needs cleanup and refactoring.

examples/publish_complex_msgs.rs

@@ -25,11 +25,16 @@ fn main() -> Result<(), ()> {
         println!("JTP serialized as: {}", serialized);
     };    
 
+    let cb3 = move |raw_c:&WrappedNativeMsg<JointTrajectoryPoint>| {
+        println!("Raw c data: {:?}", (*raw_c).positions);
+    };
+
     let sub1 = rcl_create_subscription(&mut node, "/hopp", Box::new(cb))?;
     let sub2 = rcl_create_subscription(&mut node, "/hej", Box::new(cb2))?;
+    let sub3 = rcl_create_subscription_native(&mut node, "/hej", Box::new(cb3))?;
 
     // TODO: group subscriptions in a "node" struct
-    let mut subst: Vec<Box<Sub>> = vec![Box::new(sub1), Box::new(sub2)];
+    let mut subst: Vec<Box<Sub>> = vec![Box::new(sub1), Box::new(sub2), Box::new(sub3)];
 
     // run for 10 seconds
     let mut count = 0;

src/lib.rs

@@ -94,6 +94,15 @@ where
     pub rcl_msg: WrappedNativeMsg<T>,
 }
 
+pub struct WrappedSubNative<T>
+where
+    T: WrappedTypesupport,
+{
+    pub rcl_handle: rcl_subscription_t,
+    pub callback: Box<dyn FnMut(&WrappedNativeMsg<T>) -> ()>,
+    pub rcl_msg: WrappedNativeMsg<T>,
+}
+
 impl<T> Sub for WrappedSubT<T>
 where
     T: WrappedTypesupport,
@@ -113,6 +122,25 @@ where
     }
 }
 
+impl<T> Sub for WrappedSubNative<T>
+where
+    T: WrappedTypesupport,
+{
+    fn handle(&self) -> &rcl_subscription_t {
+        &self.rcl_handle
+    }
+
+    fn rcl_msg(&mut self) -> *mut std::os::raw::c_void {
+        self.rcl_msg.void_ptr_mut()
+    }
+
+    fn run_cb(&mut self) -> () {
+        // *dont't* copy native msg to rust type.
+        // e.g. if you for instance have large image data...
+        (self.callback)(&self.rcl_msg);
+    }
+}
+
 pub fn rcl_create_context() -> Result<rcl_context_t, ()> {
     let mut ctx = unsafe { rcl_get_zero_initialized_context() };
     let isok = unsafe {
@@ -248,6 +276,42 @@ where
     }
 }
 
+pub fn rcl_create_subscription_native<T>(
+    node: &mut rcl_node_t,
+    topic: &str,
+    callback: Box<dyn FnMut(&WrappedNativeMsg<T>) -> ()>,
+) -> Result<WrappedSubNative<T>, ()>
+where
+    T: WrappedTypesupport,
+{
+    let mut subscription_handle = unsafe { rcl_get_zero_initialized_subscription() };
+    let topic_c_string = CString::new(topic).unwrap();
+
+    let result = unsafe {
+        let mut subscription_options = rcl_subscription_get_default_options();
+        subscription_options.qos = rmw_qos_profile_t::default();
+        rcl_subscription_init(
+            &mut subscription_handle,
+            node,
+            T::get_ts(),
+            topic_c_string.as_ptr(),
+            &subscription_options,
+        )
+    };
+    if result == RCL_RET_OK as i32 {
+        let wrapped_sub = WrappedSubNative {
+            rcl_handle: subscription_handle,
+            rcl_msg: WrappedNativeMsg::<T>::new(),
+            callback: callback,
+        };
+
+        Ok(wrapped_sub)
+    } else {
+        eprintln!("{}", result);
+        Err(())
+    }
+}
+
 pub fn rcl_take_subst(
     ctx: &mut rcl_context_t,
     subs: &mut Vec<Box<dyn Sub>>,