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cssvala

Vala Not Connecting to Style Sheet

I am learning Vala at the moment, after a couple years programming with Java.

After some extensive searches in the net, I discovered a way to style a GTK Window background with a css style sheet, from the example given here , that uses a GTk.Window class extension. The code compiles fine on my machine (Ubuntu 19.04) and the widgets are styled as expected.

I was trying to combine the approach with one from this site . Here, the vala class extends to Gtk.Application, instead of Gtk.Window.

The code compiles and the window opens, but the widgets don't get styled according to the style sheet. 

public class StyleApp1 : Gtk.Application {

    public StyleApp1 () {
        Object (
            application_id: "com.css.test",
            flags: ApplicationFlags.FLAGS_NONE
        );
    }

    protected override void activate () {

        var window = new Gtk.ApplicationWindow (this);
        window.set_default_size (350, 500);
        window.title = "Hello World";
        window.get_style_context().add_class("my_window");

        var screen = window.get_screen ();

        var css_provider = new Gtk.CssProvider();
        string path = "styleapp1.css";

        // test if the css file exist
        if (FileUtils.test (path, FileTest.EXISTS))
        {
            try {
                stdout.printf("File is there");
                css_provider.load_from_path(path);
                Gtk.StyleContext.add_provider_for_screen(screen, css_provider, Gtk.STYLE_PROVIDER_PRIORITY_USER);
            } catch (Error e) {
                error ("Cannot load CSS stylesheet: %s", e.message);
            }
        }

        var box = new Gtk.Box (Gtk.Orientation.VERTICAL, 10);
        window.add (box);

        var label = new Gtk.Label ("Thank you");
        box.add (label);

        var label2 = new Gtk.Label ("Stackoverflow");
        label2.get_style_context().add_class("my_class");
        box.add (label2);

        window.show_all ();
    }

    public static int main (string[] args) {
        var app = new StyleApp1 ();
        return app.run (args);
    }
}

CSS file (syleapp1.css)

GtkWindow {
    font-size: 17px;
}

.my_class {
    color: red;
}

.my_window {
    background-color: rgba (200, 100, 100, 0.9);
 }

Meson build file: 

project('com.css.test' , 'vala' , 'c')

executable (
    meson.project_name(),
   'StyleApp1.vala',

    dependencies: [
        dependency('gtk+-3.0')
    ],
install: true
)

I have no idea what I am missing. Can someone explain and point me into the right direction?

Many thank in advance.

Solution

  • It works fine here:

    screenshot

    I'm using Windows / msys2 at the moment.