Font Loading

The fonts module (enabled with the render feature) handles loading font files for use with pixel-drawing or other software rendering via ab_glyph.

impl_font_loader! Macro

Each font family crate uses the impl_font_loader! macro from fonts-rs-generator to generate a cached font loading function:

#![allow(unused)]
fn main() {
// Literal: relative to resources/
fonts_rs_generator::impl_font_loader!("Doto.ttf");

// Env var: absolute path set by build.rs via cargo:rustc-env
fonts_rs_generator::impl_font_loader!(env: "DOTO_FONT_PATH");
}

The macro generates a font() -> Option<&'static ab_glyph::FontVec> function that loads the TTF font file and caches it in a OnceLock. Subsequent calls return a reference to the cached FontVec.

Loading Modes

Embedded Fonts (embed-fonts feature)

Font files are compiled into the binary via include_bytes!:

#![allow(unused)]
fn main() {
// No runtime file access needed
fonts_rs_doto::fonts::font(); // Returns Option<&'static FontVec>
}

From Disk (default)

Fonts are loaded from a path set by build.rs via cargo:rustc-env. The impl_font_loader!(env: ...) variant reads the path from the environment variable at runtime.

Caching

Fonts are loaded once and cached in a OnceLock. Subsequent calls return a reference to the cached FontVec:

#![allow(unused)]
fn main() {
use fonts_rs_doto::fonts::font;

let font1 = font().unwrap();
let font2 = font().unwrap();
assert!(core::ptr::eq(font1 as *const _, font2 as *const _));
}

Nerd Fonts (nerd-fonts-rs)

The nerd-fonts-rs crate provides additional font loading for Nerd Fonts specifically:

1. Nerd Font (SymbolsNerdFont-Regular.ttf) - TTF file for rendering Nerd Font icons
2. Label Font (JetBrainsMonoNLNerdFont-Regular.woff2) - WOFF2 file decompressed to TTF at load time for text labels

The label font is stored as WOFF2. The convert_woff2 function decompresses it to TTF using the woff2-patched crate. If decompression fails, it falls back to parsing the data directly as TTF.

Initialization

For nerd-fonts-rs, call init() once at application startup:

#![allow(unused)]
fn main() {
// Use default base directory (relative to executable)
nerd_fonts_rs::init(None);

// Or specify a custom base directory
nerd_fonts_rs::init(Some("/usr/share/fonts/nerd-fonts"));
}