generic_font_families.rs

//! This example demonstrates generic font families,
//! which allow font faces to be selected using broadly defined
//! categories (such as serif or monospace) without selecting
//! a specific font family.
//!
//! Each generic font family is first resolved to a concrete
//! family name, which is then matched to a font in the internal
//! font database. This example loads system installed fonts to
//! populate the database.
//!
//! This feature is most useful for non-game applications;
//! most games instead choose to simply bundle their required fonts
//! to ensure a unified visual look.

use bevy::{
    color::palettes::{
        css::{WHEAT, YELLOW},
        tailwind::ZINC_600,
    },
    prelude::*,
    text::FontCx,
};

fn main() {
    let mut app = App::new();
    app.add_plugins(DefaultPlugins).add_systems(Startup, setup);

    app.run();
}

const FONT_SIZE: FontSize = FontSize::Px(25.);

fn setup(mut commands: Commands, mut font_system: ResMut<FontCx>) {
    // UI camera
    commands.spawn(Camera2d);

    commands
        .spawn((Node {
            display: Display::Grid,
            grid_template_columns: vec![RepeatedGridTrack::fr(3, 1.)],
            margin: UiRect::AUTO,
            row_gap: px(25),
            column_gap: px(15),
            ..Default::default()
        },))
        .with_children(|builder| {
            builder.spawn((
                Node {
                    justify_self: JustifySelf::Center,
                    grid_column: GridPlacement::span(3),
                    margin: UiRect::bottom(px(15)),
                    ..default()
                },
                Text::new("Generic Font Families"),
                TextFont::from_font_size(FONT_SIZE),
                Underline,
            ));

            let outline = Outline {
                color: ZINC_600.into(),
                width: px(2.),
                offset: px(4.),
            };

            for (source, description) in [
                (FontSource::SansSerif, "generic sans serif font"),
                (FontSource::Serif, "generic serif font"),
                (FontSource::Fantasy, "generic fantasy font"),
                (FontSource::Cursive, "generic cursive font"),
                (FontSource::Monospace, "generic monospace font"),
            ] {
                builder.spawn((
                    Text::new(description),
                    TextFont::from(source.clone()).with_font_size(FONT_SIZE),
                    TextColor(WHEAT.into()),
                    TextLayout::new_with_justify(Justify::Center),
                    outline,
                ));

                builder.spawn((
                    Text::new(format!("FontSource::{source:?}")),
                    TextFont::from_font_size(FONT_SIZE),
                    TextColor(YELLOW.into()),
                    TextLayout::new_with_justify(Justify::Center),
                    outline,
                ));

                // Get the family name for the `FontSource` from `FontCx`.
                // `get_family` only returns `None` for `FontSource::Handle`.
                let family_name = font_system.get_family(&source).unwrap();
                builder.spawn((
                    Text::new(family_name),
                    TextFont::from_font_size(FONT_SIZE),
                    TextLayout::new_with_justify(Justify::Center),
                    outline,
                ));
            }
        });
}