sugarloaf 0.4.4

Sugarloaf is Rio rendering engine, designed to be multiplatform. It is based on WebGPU, Rust library for Desktops and WebAssembly for Web (JavaScript). This project is created and maintained for Rio terminal purposes but feel free to use it.
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// Copyright (c) 2023-present, Raphael Amorim.
//
// This source code is licensed under the MIT license found in the
// LICENSE file in the root directory of this source tree.

//! Span-level styling: the type set that survived the rich-text
//! emission deletion. `SpanStyle` is shared across grid emit (via
//! `font_cache::FontCache::find_best_font_match`), UI text shaping
//! (`crate::text`), and rio's frontend (font_cache + grid_emit). The
//! decoration enums are read by the underline / strikethrough quad
//! batches in the renderer.

use crate::sugarloaf::primitives::SugarCursor;
use crate::{DrawableChar, Graphic};
use swash::{Attributes, Setting};

/// Index into a font setting cache.
pub type FontSettingKey = u32;

/// Cache of tag/value pairs for font settings.
#[derive(Default, Clone, Debug)]
pub struct FontSettingCache<T: Copy + PartialOrd + PartialEq + std::fmt::Debug> {
    settings: Vec<Setting<T>>,
    lists: Vec<FontSettingList>,
    tmp: Vec<Setting<T>>,
}

impl<T: Copy + PartialOrd + PartialEq + std::fmt::Debug> FontSettingCache<T> {
    pub fn get(&self, key: u32) -> &[Setting<T>] {
        if key == !0 {
            &[]
        } else {
            self.lists
                .get(key as usize)
                .map(|list| list.get(&self.settings))
                .unwrap_or(&[])
        }
    }

    pub fn clear(&mut self) {
        self.settings.clear();
        self.lists.clear();
        self.tmp.clear();
    }
}

/// Sentinel for an empty set of font settings.
pub const EMPTY_FONT_SETTINGS: FontSettingKey = !0;

/// Range within a font setting cache.
#[derive(Copy, Clone, Debug)]
struct FontSettingList {
    pub start: u32,
    pub end: u32,
}

impl FontSettingList {
    pub fn get<T>(self, elements: &[T]) -> &[T] {
        elements
            .get(self.start as usize..self.end as usize)
            .unwrap_or(&[])
    }
}

#[repr(u8)]
#[derive(Copy, Clone, PartialEq, Debug, Default)]
pub enum UnderlineShape {
    #[default]
    Regular = 0,
    Dotted = 1,
    Dashed = 2,
    Curly = 3,
}

#[derive(Copy, Clone, PartialEq, Debug)]
pub struct UnderlineInfo {
    pub is_doubled: bool,
    pub shape: UnderlineShape,
}

#[derive(Copy, Clone, PartialEq, Debug)]
pub enum SpanStyleDecoration {
    Underline(UnderlineInfo),
    Strikethrough,
}

#[derive(Copy, Clone, PartialEq, Debug)]
pub struct SpanStyle {
    pub font_id: usize,
    /// Unicode width.
    pub width: f32,
    /// Font attributes.
    pub font_attrs: Attributes,
    /// Font color.
    pub color: [f32; 4],
    /// Background color.
    pub background_color: Option<[f32; 4]>,
    /// Font variations.
    pub font_vars: FontSettingKey,
    /// Enable underline / strikethrough decoration.
    pub decoration: Option<SpanStyleDecoration>,
    /// Decoration color.
    pub decoration_color: Option<[f32; 4]>,
    /// Cursor style.
    pub cursor: Option<SugarCursor>,
    /// Media (kitty-protocol image).
    pub media: Option<Graphic>,
    /// Drawable character (Unicode box-drawing / Powerline / sextants).
    pub drawable_char: Option<DrawableChar>,
    /// PUA constraint width: how many cells the glyph should visually
    /// fill. None for normal glyphs, Some(1.0) or Some(2.0) for PUA
    /// glyphs. Does NOT affect positioning/advance — only compositor
    /// scaling.
    pub pua_constraint: Option<f32>,
    /// Optional per-glyph Nerd Font constraint (size / alignment /
    /// padding) sourced from the Nerd Fonts patcher table. When set,
    /// the compositor lays the glyph out using the constraint math
    /// in `nerd_font_attributes` instead of the generic cell-centered
    /// fit. Only populated by the renderer for codepoints with a
    /// table entry (`get_constraint`).
    pub nerd_font_constraint: Option<crate::font::nerd_font_attributes::Constraint>,
}

impl Default for SpanStyle {
    fn default() -> Self {
        Self {
            font_id: 0,
            width: 1.0,
            font_attrs: Attributes::default(),
            font_vars: EMPTY_FONT_SETTINGS,
            color: [1.0, 1.0, 1.0, 1.0],
            background_color: None,
            cursor: None,
            decoration: None,
            decoration_color: None,
            media: None,
            drawable_char: None,
            pua_constraint: None,
            nerd_font_constraint: None,
        }
    }
}