A beginner's doubts

[Vjze]

I am a beginner in Rust, looking for a practical and beautiful GUI. When I first saw Slint, I fell in love with her. But I have some doubts, why Slint is so much slower than egui f

20230725_230141.mp4

or the same query code, a novice question. (my english is poor, sorry)
https://gitee.com/weijingze/rust_slint.git，

[Vadoola]

I get a 403 forbidden error when trying to access your code.

[tronical]

Thanks for reporting this issue. It looks like populating the large table is slow. It would indeed be interesting to see how the code looks like that you're using the populate the model. Like @Vadoola I can't seem to access the source code :(. Could it be that the repository is not public? (yes, I removed the trailing comma from the URL).

[Vjze]

slint_app.zip

I get a 403 forbidden error when trying to access your code.

Thanks for reporting this issue. It looks like populating the large table is slow. It would indeed be interesting to see how the code looks like that you're using the populate the model. Like @Vadoola I can't seem to access the source code :(. Could it be that the repository is not public? (yes, I removed the trailing comma from the URL).

I get a 403 forbidden error when trying to access your code.

Thanks for reporting this issue. It looks like populating the large table is slow. It would indeed be interesting to see how the code looks like that you're using the populate the model. Like @Vadoola I can't seem to access the source code :(. Could it be that the repository is not public? (yes, I removed the trailing comma from the URL).

https://github.com/Vjze/Rust_demo.git

[tronical]

Thanks for updating the source code - I can see it now. I can't run it (because it requires access to the database), but from a glance at the code I think I can see what the issue might be.

In the callback that's invoked when pressing the button (after selecting for example "Carton"), this function is called:

fn get_carton_result(text: String,app_weak:Weak<App>)  {
    let rt = tokio::runtime::Runtime::new().unwrap();
   let res =  rt.block_on(async {
        let row_data = carton_work(text).await;
        app_weak
        .unwrap()
        .global::<TableView>()
        .set_row_data(row_data.into());
        // app_weak
        //     .unwrap()
        //     .global::<TableView>()
        //     .set_row_data(row_data.into());
    });
//     res
}

The call to rt.block_on will block the main thread and thus make the UI unresponsive.

What I would recommend instead is something like we've done in cargo-ui:

1. Initialize your TableView's row_data with an empty VecModel.
2. Create a thread
3. In that thread you have your long-running operations using tokio. In there it's okay to call block_on. The thread needs a clone of Weak<App>.
4. When you have received results from your database, use Weak::upgrade_in_event_loop() to invoke a closure in the Slint main thread. In there you get access to ComponentHandle<App>, you can fetch your row_data() and downcast to the VecModel, so that you can push more rows into it, like in this example.

This way the UI thread remains always responsive while your worker thread uses tokio to spawn tasks to interact with your database.

Does that make sense? :)

[Vjze]

20230825_000419.mp4

Thanks for your guidance, it works fine. However, after the ComboBox control selects other options, it seems that the first option cannot be selected. Is this my problem?

[ogoffart]

That's a bug. I created issue #3345 for it

[Vjze]

Thanks for updating the source code - I can see it now. I can't run it (because it requires access to the database), but from a glance at the code I think I can see what the issue might be.

In the callback that's invoked when pressing the button (after selecting for example "Carton"), this function is called:

fn get_carton_result(text: String,app_weak:Weak<App>)  {
    let rt = tokio::runtime::Runtime::new().unwrap();
   let res =  rt.block_on(async {
        let row_data = carton_work(text).await;
        app_weak
        .unwrap()
        .global::<TableView>()
        .set_row_data(row_data.into());
        // app_weak
        //     .unwrap()
        //     .global::<TableView>()
        //     .set_row_data(row_data.into());
    });
//     res
}

The call to rt.block_on will block the main thread and thus make the UI unresponsive.

What I would recommend instead is something like we've done in cargo-ui:

1. Initialize your TableView's row_data with an empty VecModel.
2. Create a thread
3. In that thread you have your long-running operations using tokio. In there it's okay to call block_on. The thread needs a clone of Weak<App>.
4. When you have received results from your database, use Weak::upgrade_in_event_loop() to invoke a closure in the Slint main thread. In there you get access to ComponentHandle<App>, you can fetch your row_data() and downcast to the VecModel, so that you can push more rows into it, like in this example.

This way the UI thread remains always responsive while your worker thread uses tokio to spawn tasks to interact with your database.

Does that make sense? :)

Thanks for the guide, I'm trying to use multithreading, but I'm getting an error,
'std::rc::Rc<(dyn slint::Model<Data = ModelRc> + 'static)>` cannot be sent between threads safely', Rc cannot implement Send in multiple threads, may I have What about other ways to use set_row_data() directly?

[puli1027]

@Vjze I can give you some reference

    app.global::<PanelViewGlobal>().on_clicked({
        let app_weak = app.as_weak();
        move || {
            let app_weak = app_weak.clone();
            //multi-thread
            async_std::task::spawn(async move {
                let mut i = 0;
                loop {
                    if i > 90 {
                        break;
                    }
                    task::sleep(Duration::from_millis(200)).await;
                    app_weak
                        .upgrade_in_event_loop(|ui| {
                            ui.global::<PanelViewGlobal>().set_value(
                                chrono::Local::now()
                                    .format("%Y-%m-%d %H:%M:%S")
                                    .to_string()
                                    .into(),
                            );
                        })                             
                        .unwrap();
                    i += 1;
                }
            });
        }
    });

[ogoffart]

(I converted this issue to a discussion, since it is not really a bug report)

Another way would be to use slint::spawn_local to run your without blocking the UI.