Function reaper_low::create_cpp_to_rust_control_surface

pub unsafe fn create_cpp_to_rust_control_surface(
    callback_target: NonNull<Box<dyn IReaperControlSurface>>
) -> NonNull<IReaperControlSurface>

Creates an IReaperControlSurface object on C++ side and returns a pointer to it.

This function is provided because plugin_register() isn’t going to work if you just pass it a Rust struct as in reaper.plugin_register("csurf_inst", my_rust_struct). Rust structs can’t implement C++ virtual base classes.

This function doesn’t yet register the control surface! The usual REAPER C++ way to register a control surface still applies. You need to pass the resulting pointer to plugin_register().

Example

use reaper_low::{create_cpp_to_rust_control_surface, delete_cpp_control_surface, IReaperControlSurface};
use std::ffi::CString;
use std::ptr::NonNull;
use c_str_macro::c_str;

unsafe {
    // Register
    #[derive(Debug)]
    struct MyControlSurface;
    impl IReaperControlSurface for MyControlSurface {
        fn SetTrackListChange(&self) {
            println!("Tracks changed");
        }
    }
    let rust_cs: Box<dyn IReaperControlSurface> = Box::new(MyControlSurface);
    let thin_ptr_to_rust_cs: NonNull<_> = (&rust_cs).into();
    let cpp_cs = create_cpp_to_rust_control_surface(thin_ptr_to_rust_cs);
    reaper.plugin_register(c_str!("csurf_inst").as_ptr(), cpp_cs.as_ptr() as _);
    // Unregister
    reaper.plugin_register(c_str!("-csurf_inst").as_ptr(), cpp_cs.as_ptr() as _);
    delete_cpp_control_surface(cpp_cs);
}

Cleaning up

If you register a control surface, you also must take care of unregistering it at the end. This is especially important for VST plug-ins because they live shorter than a REAPER session! If you don’t unregister the control surface before the VST plug-in is destroyed, REAPER will crash because it will attempt to invoke functions which are not loaded anymore.

In order to avoid memory leaks, you also must take care of removing the C++ counterpart surface by calling delete_cpp_control_surface().

Safety

This function is highly unsafe for all the reasons mentioned above. Better use the medium-level API instead, which makes registering a breeze.