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
    5·
    21 days 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
      5·
      20 days 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
        3·
        20 days 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.

        • zlatko@programming.dev
          1·
          8 days 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
          1·
          20 days 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.

      • d_k_bo
        2·
        20 days 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
          1·
          20 days 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.