Invoking global callback from rust

[Murmele]

Hello,

I am trying to invoke a global callback from rust and handling it in slint. Using component callbacks works fine, but I did not find any documentation doing it for global callbacks.

The idea is to have a global callback in the Settings namespace. This global callback can be called from rust with invoke_global_callback_invoked_from_rust(). In slint I wanna react on the call with something like

Settings.global_callback_invoked_from_rust => { ... }

Is there a way to react on global callback invokations from rust?

• Invoking component callback from rust and handling in slint
• Invoking component callback from slint and handling in rust
• Invoking global callback from rust and handling in slint
• Invoking global callback from slint and handling in rust
• Setting global property from rust and slint component properties change

lib.rs

use std::error::Error;

slint::include_modules!();

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

    // Invoking a global callback from rust. Slint components shall react on it
    ui.global::<Settings>().invoke_global_callback_invoked_from_rust("Invoked a global callback from rust".into());

    // Invoking a component callback works fine
    ui.invoke_test_input_from_rust("Invoked a component callback from rust.".into());

    ui.on_component_callback({
        let ui_handle = ui.as_weak();
        move || {
            let ui = ui_handle.unwrap();
            // Setting a global property works fine
            ui.global::<Settings>().set_text("Globally property changed from rust from the component callback".into());
        }
    });

    // Callback handler from the global. Will be triggered when in slint the global callback gets executed
    ui.global::<Settings>().on_global_callback_invoked_from_slint({
        let ui_handle = ui.as_weak();
        move || {
            let ui = ui_handle.unwrap();
            ui.global::<Settings>().set_text("Globally property changed from rust from the global callback".into());
        }
    });
    ui.run()?;
    Ok(())
}

mainwin.slint

import { Button, VerticalBox } from "std-widgets.slint";
// Exporting the global again from the main slint file to be able to access it from rust
export { Settings } from "settings.slint";
// Import to access from the AppWindow component
import { Settings } from "settings.slint";

export component AppWindow inherits Window {
    property<string> text: "No component callback invoke triggered from rust";
    property<string> text2: "No global callback invoke triggered from rust";
    callback component_callback(); // Implemented in rust

    // Invoked in the rust code
    callback test_input_from_rust(string);
    test_input_from_rust(input) => {
        text = input;
    }

    // // Does not work yet!
    // Settings.global_callback_invoked_from_rust => {
    //     text2 = input;
    // }

    VerticalBox {
        Text { text: root.text; }

        Text { text: root.text2; }

        Text { text: Settings.text; }

        // Trigger component callback implemented in rust
        // In rust we change the global property `Settings.text`
        // Which will trigger a change of the TextLabel text
        Button {
            text: "Invoke component callback";
            clicked => {
                root.component_callback();
            }
        }

        // Trigger global callback implemented in rust
        Button {
            text: "Invoke global settings callback";
            clicked => {
                Settings.global_callback_invoked_from_slint();
            }
        }
    }
}

settings.slint

export global Settings {
    callback global_callback_invoked_from_slint();
    callback global_callback_invoked_from_rust(t: string);
    // When this property is set in rust, the
    // property of some components changes
    in property<string> text: "No callback triggered. Click one of the buttons below";
}