It might be lack of sleep, but I can’t figure this out.

I have a Label, and I want its text to be red when it represents an error, and I want it be green when it represent “good to go”.

I found search result for C and maybe a solution for Python, but nothing for Rust.

I tried manually setting the css-classes property and running queue_draw(); it didn’t work.

I can have a gtk::Box or a Frame that I place where the Label should go, then declare two Labels, and use set_child() to switch between them, but that seems like an ugly solution.

Do you have a solution?

SOLVED:

I have to add a “.” before declaring a CSS “thing” for it to be considered a class.

Ex:

.overlay {
        background: rgba(60, 60, 60, 1);
        font-size: 25px;
}

instead of:

overlay {
        background: rgba(60, 60, 60, 1);
        font-size: 25px;)
}

Just use label.add_css_class(), label.remove_css_class() or label.set_css_classes() and make sure to properly load your CSS style sheets,

Source: the comment of d_k_bo@feddit.org

  • d_k_bo@feddit.org
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    2 months ago

    Just use label.add_css_class(), label.remove_css_class() or label.set_css_classes() and make sure to properly load your CSS style sheets, this is usually done by including them as a resource alongside .ui files and icons. If you are using libadwaita, you can also use its predefined style classes.

    full example (requires nightly toolchain)
    #!/usr/bin/env -S cargo +nightly -Zscript
    ---
    [dependencies]
    gtk = { package = "gtk4", version = "0.9.3", features = ["v4_12"] }
    ---
    
    use gtk::{glib, prelude::*};
    
    const STYLESHEET: &str = r#"
    .green {
        color: green;
    }
    .red {
        color: red;
    }
    "#;
    
    fn main() -> glib::ExitCode {
        let app = gtk::Application::builder()
            .application_id("org.example.HelloWorld")
            .build();
    
        app.connect_activate(|app| {
            let window = gtk::ApplicationWindow::builder()
                .application(app)
                .title("Hello, World!")
                .build();
    
            // Stylesheets are usually bundled with application resources
            // and automatically loaded
            let css_provider = gtk::CssProvider::new();
            css_provider.load_from_string(STYLESHEET);
            gtk::style_context_add_provider_for_display(
                &RootExt::display(&window),
                &css_provider,
                0
            );
    
            let box_ = gtk::Box::new(gtk::Orientation::Vertical, 6);
    
            let label = gtk::Label::builder()
                .label("Hello, World")
                .css_classes(["green"].as_slice())
                .build();
            box_.append(&label);
    
    
            let button = gtk::Button::builder()
                .label("Toggle Color")
                .build();
            box_.append(&button);
    
            button.connect_clicked(glib::clone!(#[weak] label, move |_| {
                if label.has_css_class("red") {
                    label.add_css_class("green");
                    label.remove_css_class("red");
                } else {
                    label.add_css_class("red");
                    label.remove_css_class("green");
                }
            }));
    
            window.set_child(Some(&box_));
            window.present();
        });
    
        app.run()
    }
    
    • Doods@infosec.pubOP
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      2 months ago

      This is embarrassing, but when was it not?

      I have to add a “.” before the name of a css class, I must learn my tools.

      • zlatko@programming.dev
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        2 months ago

        I mean, it is not embarrassing for you. In the browser, the CSS’s “native platform”, you add classes, via the JavaScript API, without the dot. It’s not a stupid assumption.

        To have to add the dot in the CSS class name seems a bit of an oversight in the gtkrs API.

        • d_k_bo@feddit.org
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          2 months ago

          I think you understood their comment wrong. In your code (e.g. label.add_css_class("green");) you don’t use a dot, but in the CSS stylesheet. It works the same as with HTML/JS/CSS.

        • zlatko@programming.dev
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          1 month ago

          (sorry for the late response, I have to get in the habit of checking my Lemmy account)

          No, I get that - a stylesheet denotes a class by having a dot. A JavaScript API for adding a CSS class omits this redundancy.

          I was saying that the author might not be wrong to want to avoid the redundancy in rust example as well (since it explicitly mentions CSS classes).

      • d_k_bo@feddit.org
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        2 months ago

        Well, that’s CSS :D

        Note that if you create a custom Widget class, you can set a CSS name, wich isn’t a CSS class and doesn’t use a leading dot.

        • Doods@infosec.pubOP
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          2 months ago

          you can set a CSS name, wich isn’t a CSS class and doesn’t use a leading dot.

          Yeah that’s what I’ve been using all along.