spectral-font/src/font.rs

use std::sync::Arc;

#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
pub enum FontStyle {
    Regular = 0,
    Bold = 1,
    Italic = 2,
    BoldItalic = 3,
}

impl Default for FontStyle {
    fn default() -> Self { FontStyle::Regular }
}

pub struct Font {
    pub id: u32,
    pub data: Arc<Vec<u8>>,
    pub index: u32,
    pub style: FontStyle,
    pub family_name: String,
    pub rasterizer: fontdue::Font,
}

impl Font {
    pub fn from_bytes(id: u32, data: Arc<Vec<u8>>, index: u32, style: FontStyle) -> Option<Self> {
        let settings = fontdue::FontSettings {
            collection_index: index,
            scale: 40.0,
            load_substitutions: true,
        };
        let rasterizer = fontdue::Font::from_bytes(&**data, settings).ok()?;
        let family_name = format!("Font-{}", id);
        Some(Self { id, data, index, style, family_name, rasterizer })
    }

    pub fn rasterize_glyph(&self, glyph_id: u16, px: f32) -> (fontdue::Metrics, Vec<u8>) {
        self.rasterizer.rasterize_indexed(glyph_id, px)
    }

    pub fn lookup_glyph(&self, ch: char) -> u16 {
        self.rasterizer.lookup_glyph_index(ch)
    }
}

pub struct FontFamily {
    pub name: String,
    pub fonts: [Option<Font>; 4],
}

impl FontFamily {
    pub fn new(name: &str) -> Self {
        Self { name: name.to_string(), fonts: [None, None, None, None] }
    }

    pub fn add_font(&mut self, font: Font) {
        self.fonts[font.style as usize] = Some(font);
    }

    pub fn get_font(&self, style: FontStyle) -> Option<&Font> {
        self.fonts[style as usize].as_ref()
            .or_else(|| self.fonts[FontStyle::Bold as usize].as_ref())
            .or_else(|| self.fonts[FontStyle::Italic as usize].as_ref())
            .or_else(|| self.fonts[FontStyle::Regular as usize].as_ref())
    }
}