CSS Generation

The css module provides CSS string constants for GTK and web usage.

GTK Font-Face CSS

The font_face_css() function generates a version-adapted @font-face CSS string at runtime. It detects the GTK4 library version and adjusts the src descriptor syntax for compatibility:

• GTK >= 4.10: emits src: url("...") format("truetype") for better spec compliance with the new GtkCssParser.
• GTK < 4.10: emits src: url("...") without a format() hint to avoid parse errors with the legacy parser.

It is loaded automatically by init() when the gtk feature is enabled.

#![allow(unused)]
fn main() {
use nerd_fonts_rs::css::font_face_css;

let css = font_face_css();
// The CSS references GResource URLs:
// resource:///io/smearor/nerd_fonts/SymbolsNerdFont-Regular.ttf
// resource:///io/smearor/nerd_fonts/SymbolsNerdFontMono-Regular.ttf
}

The CSS defines:

• @font-face for NerdFontsSymbolsOnly (proportional)
• @font-face for NerdFontsSymbolsOnlyMono (monospace)
• .nerd-icon class for proportional icons
• .nerd-icon-mono class for monospace icons

The static FONT_FACE_CSS constant retains the baseline CSS (without format() hints) for backward compatibility and testing.

Runtime Version Detection

The GtkVersion struct wraps the runtime GTK4 version and provides comparison helpers:

#![allow(unused)]
fn main() {
use nerd_fonts_rs::css::GtkVersion;

#[cfg(feature = "gtk")]
let version = GtkVersion::runtime();

let legacy = GtkVersion::new(4, 8, 0);
assert!(!legacy.at_least(4, 10));

let modern = GtkVersion::new(4, 14, 2);
assert!(modern.at_least(4, 10));
}

GResource Prefix

The GRESOURCE_PREFIX constant defines where font files are registered in the GResource system:

#![allow(unused)]
fn main() {
use nerd_fonts_rs::css::GRESOURCE_PREFIX;

assert_eq!(GRESOURCE_PREFIX, "/io/smearor/nerd_fonts");
}

Manual CSS Loading

If you need to load the CSS manually (e.g., in a custom initialization flow):

#![allow(unused)]
fn main() {
use gtk4::CssProvider;

let provider = gtk4::CssProvider::new();
let css = nerd_fonts_rs::css::font_face_css();

#[cfg(feature = "v4_12")]
provider.load_from_string(&css);
#[cfg(not(feature = "v4_12"))]
{
    #[allow(deprecated)]
    provider.load_from_data(&css);
}

if let Some(display) = gtk4::gdk::Display::default() {
    gtk4::style_context_add_provider_for_display(
        &display,
        &provider,
        gtk4::STYLE_PROVIDER_PRIORITY_APPLICATION,
    );
}
}