Calling WinPixEvenRuntime ABI from Rust and windows-rs

winpix.rs

#[derive(Copy, Clone)]
struct WinPixEventRuntime {
    begin_event: BeginEventOnCommandList,
    end_event: EndEventOnCommandList,
    set_marker: SetMarkerOnCommandList,
}

impl WinPixEventRuntime {
    pub fn create() -> Option<WinPixEventRuntime> {
        unsafe {
            let module = LoadLibraryA("WinPixEventRuntime.dll\0");
            
            let p_begin_event = GetProcAddress(module, "PIXBeginEventOnCommandList\0");
            let p_end_event = GetProcAddress(module, "PIXEndEventOnCommandList\0");
            let p_set_marker = GetProcAddress(module, "PIXSetMarkerOnCommandList\0");

            if p_begin_event.is_some() && p_end_event.is_some() && p_set_marker.is_some() {
                return Some(WinPixEventRuntime {
                    begin_event: std::mem::transmute::<*const usize, BeginEventOnCommandList>(
                        p_begin_event.unwrap() as *const usize),
                    end_event: std::mem::transmute::<*const usize, EndEventOnCommandList>(
                        p_end_event.unwrap() as *const usize),
                    set_marker: std::mem::transmute::<*const usize, SetMarkerOnCommandList>(
                        p_set_marker.unwrap() as *const usize),
                });
            }
            None
        }
    }

    pub fn begin_event_on_command_list(&self, command_list: ID3D12GraphicsCommandList, color: u64, name: &str) {
        unsafe {
            let null_name = CString::new(name).unwrap();
            let fn_begin_event : BeginEventOnCommandList = self.begin_event;
            let p_cmd_list = std::mem::transmute::<IUnknown, *const core::ffi::c_void>(command_list.0.clone());
            fn_begin_event(p_cmd_list, color, PSTR(null_name.as_ptr() as _));
        }
    }

    pub fn end_event_on_command_list(&self, command_list: ID3D12GraphicsCommandList) {
        unsafe {
            let fn_end_event : EndEventOnCommandList = self.end_event;
            let p_cmd_list = std::mem::transmute::<IUnknown, *const core::ffi::c_void>(command_list.0.clone());
            fn_end_event(p_cmd_list);
        }
    }

    pub fn set_marker_on_command_list(&self, command_list: ID3D12GraphicsCommandList, color: u64, name: &str) {
        unsafe {
            let null_name = CString::new(name).unwrap();
            let fn_set_marker : SetMarkerOnCommandList = self.set_marker;
            let p_cmd_list = std::mem::transmute::<IUnknown, *const core::ffi::c_void>(command_list.0.clone());
            fn_set_marker(p_cmd_list, color, PSTR(null_name.as_ptr() as _));
        }
    }
}