Update to property from callback failing after update to property from background thread.

[winarama]

Howzit,

I am writing an application which takes user input in the main thread, sends it over the network and records on the GUI what was sent via a callback.

At the same time I have a background thread which listens for network input and records said input on the GUI when received.

The issue I am having is that user input in the main thread is not showing on the GUI after I have received network input and displayed it on the GUI in the background thread.

The strange thing is that input is being read and sent over the network but the ui.set_output() (shown in the callback code block below) is called but doesn't render any changes to the GUI. It also works fine if no network input is received in the background thread.

Anyone got any idea?

// Callback
ui.on_capture_user_input({
    let ui_handle = ui.as_weak();
    move || {
        // Get input
        let ui = ui_handle.unwrap();
        println!("User input is : {}", &ui.get_input());

        // Send data
        ClientNode::send(&ui.get_input());

        // Update GUI
        ui.set_output(ui.get_output() + &ui.get_input());
    }
});

// Background thread
fn spawn_ui_background_thread(handle_weak: Weak<AppWindow>) {
    std::thread::spawn(move || {
        loop {
            let input = ClientNode::receive();

            // Forward the data to the main thread using invoke_from_event_loop
            let handle_copy = handle_weak.clone();
            let _ = slint::invoke_from_event_loop(move || {
                handle_copy.unwrap().set_output(handle_copy.unwrap().get_output() + &input);
            });
        }
    });
}

[ogoffart]

I can't see a problem in the code snippets providen.

[winarama]

Yeah it's an odd one alright.

User input displays on the GUI correctly until network input is received. The received network input is displayed correctly on the GUI but the next user input is not displayed on the GUI (although it is sent over the network). However the second user input entered does display on the GUI.

So it is only the first user input following a network input that doesn't display on the GUI. I've listed the process below;

1. Enter user input & send -> User input displays on GUI
2. Receive network input -> Network input displays on GUI
3. Enter user input & send -> User input DOES NOT display on GUI
4. Enter user input & send -> User input displays on GUI

Could this be some kind of buffer issue on the output property that isn't getting flushed by the background thread?

[winarama]

FFS, figured it out.

There was a call to .replace("\n", "") in the ClientNode::receive() function.

The removal of the newline char was causing the issue. It works now.