Initialising properties with Rust

[iaminapickle]

Hi friends!

I want to initialise certain parameters of my app with values I will store in a JSON file and I want to know the best way to do so. I want the app to maintain the same layout (position, size, etc) of certain components as when the user last closed it.

Consider this minimal example:

// .slint file
export global FooGlobal {
    in-out property <length> foo_width;
}

component Foo inherits Rectangle {
    in-out property <length> foo_width;
    
    background: gray;
    height: 100%;
    width: foo-width;
}

export component FooWindow inherits Window {
    Foo {}
}

I've tried using the init callback but the documentation says to not use it for initialisation and also using a setter as shown below but Foo.width doesn't seem to change.

// .rs file
// Prevent console window in addition to Slint window in Windows release builds when, e.g., starting the app via file manager. Ignored on other platforms.
#![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]

use std::error::Error;

slint::include_modules!();

fn main() -> Result<(), Box<dyn Error>> {
    let app = FooWindow::new()?;
    app.global::<FooGlobal>().set_foo_width(100.0);
    
    app.run()?;

    Ok(())
}

How would you go about setting foo-width?

Thanks in advance!

[ogoffart]

you can also call app.set_foo_with(100.0) to initialize the "other" foo-width (the one declared on the component itself)

[iaminapickle]

Totally right about having duplicate properties - i had some misunderstandings about how that worked.

However I do like your approach better but I get this error when i try app.set_foo_width(100.0).

error[E0599]: no method named `set_foo_width` found for struct `FooWindow` in the current scope
   --> src/main.rs:11:9
    |
11  |     app.set_foo_width(100.0);
    |         ^^^^^^^^^^^^^ method not found in `FooWindow`

[bjorn]

Because FooWindow doesn't have a foo_width property, only Foo has. You will need to expose this property on your exported component (and forward it on the Slint side, if needed). Or use the global and bind like width: FooGlobal.foo_width instead.