Slider value update not working after dragging

[J0hannes101]

Bug Description

What is the bug?

• After manually dragging the slider, the slider position no longer updates via the timer.

Expected behavior:

• slider should continue to update every second even after manual user interaction.

What happened instead:

• Once the slider is dragged by the user, set_slider_value has no effect, the slider stays at the dragged value, while the text updates

Steps to reproduce:

• Run the program
• Observe the slider updating every second
• Drag the slider manually
• Notice that updates stop despite the timer still running

Reproducible Code (if applicable)

ui.slint:

import { VerticalBox, Slider, Button } from "std-widgets.slint";

export component AppWindow inherits Window {

    in property <float> slider_value;
    
    VerticalLayout {
        Text {
            text: "Slider Value: " + slider_value;
        }
        
        Slider {
            minimum: 0;
            maximum: 100;
            value: slider_value;
        }

    }
}

main.rs:

use std::error::Error;
use std::time::Duration;

slint::include_modules!();

fn main() -> Result<(), Box<dyn Error>> {
    let ui = AppWindow::new()?;
    let mut time = 0;
    
    let timer = slint::Timer::default();
    timer.start(slint::TimerMode::Repeated, Duration::from_secs(1), {
        let ui_clone = ui.as_weak();
        move || {
            let ui_clone = ui_clone.unwrap();
                ui_clone.set_slider_value(time as f32);
                println!("set position: {}", time);
                time += 1; 
            }
        }
    );
    
    ui.run()?;
    Ok(())
}

Environment Details

• Slint Version: 1.11.0
• Platform/OS: Arch Linux x86_64 - Wayland
• Programming Language: Rust
• Backend/Renderer: Qt

Product Impact

No response

[FloVanGH]

Hi,
and thank you for your report.

I have converted this into a discussion because it's not a bug. To get it to work you need to use a two-way binding.

I have adjusted your code so that it works:

import { VerticalBox, Slider, Button } from "std-widgets.slint";

export component AppWindow inherits Window {

    in property <float> slider_value <=> slider.value;
    
    VerticalLayout {
        Text {
            text: "Slider Value: " + slider_value;
        }
        
        slider := Slider {
            minimum: 0;
            maximum: 100;
        }

    }
}

use std::error::Error;
use std::time::Duration;

slint::include_modules!();

fn main() -> Result<(), Box<dyn Error>> {
    let ui = AppWindow::new()?;

    let timer = slint::Timer::default();
    timer.start(slint::TimerMode::Repeated, Duration::from_secs(1), {
        let ui_clone = ui.as_weak();
        move || {
            let ui_clone = ui_clone.unwrap();
            ui_clone.set_slider_value(ui_clone.get_slider_value() + 1.);
            println!("set position: {}", ui_clone.get_slider_value());
        }
    });

    ui.run()?;
    Ok(())
}

[J0hannes101]

Thanks, that worked.