mathra 1.1.0

//! Box model: everything drawn has a width, a height above the baseline
//! and a depth below it. Coordinates in font units, y pointing up.

use ttf_parser::GlyphId;

#[derive(Debug, Clone, PartialEq)]
pub enum Item {
    Glyph {
        id: GlyphId,
        x: f32,
        y: f32,
        scale: f32,
        color: Option<String>,
    },
    /// Filled rectangle; (x, y) is the lower left corner.
    Rule {
        x: f32,
        y: f32,
        width: f32,
        height: f32,
        color: Option<String>,
    },
    /// Straight segment (cancels).
    Line {
        x1: f32,
        y1: f32,
        x2: f32,
        y2: f32,
        thickness: f32,
        color: Option<String>,
    },
    /// Ellipse outline (`\textcircled`).
    Ellipse {
        cx: f32,
        cy: f32,
        rx: f32,
        ry: f32,
        thickness: f32,
        color: Option<String>,
    },
}

impl Item {
    fn shift(&mut self, dx: f32, dy: f32) {
        match self {
            Item::Glyph { x, y, .. } | Item::Rule { x, y, .. } => {
                *x += dx;
                *y += dy;
            }
            Item::Line { x1, y1, x2, y2, .. } => {
                *x1 += dx;
                *x2 += dx;
                *y1 += dy;
                *y2 += dy;
            }
            Item::Ellipse { cx, cy, .. } => {
                *cx += dx;
                *cy += dy;
            }
        }
    }

    fn colorize(&mut self, new: &str) {
        let color = match self {
            Item::Glyph { color, .. } | Item::Rule { color, .. } | Item::Line { color, .. } | Item::Ellipse { color, .. } => color,
        };
        if color.is_none() {
            *color = Some(new.to_string());
        }
    }
}

#[derive(Debug, Clone, Default, PartialEq)]
pub struct MathBox {
    pub width: f32,
    pub height: f32,
    pub depth: f32,
    pub items: Vec<Item>,
    /// Italic correction of the last glyph: how far right the superscript should move.
    pub italic: f32,
    /// Where an accent should be centered, when the box is a single glyph.
    pub accent_point: Option<f32>,
    /// The box is a single glyph (affects scripts and accents).
    pub single_glyph: bool,
}

impl MathBox {
    pub fn empty() -> MathBox {
        MathBox::default()
    }

    pub fn space(width: f32) -> MathBox {
        MathBox { width, ..MathBox::default() }
    }

    pub fn bar(width: f32, thickness: f32, base: f32) -> MathBox {
        MathBox {
            width,
            height: (base + thickness).max(0.0),
            depth: (-base).max(0.0),
            items: vec![Item::Rule { x: 0.0, y: base, width, height: thickness, color: None }],
            ..MathBox::default()
        }
    }

    /// Places `other` with its origin at (dx, dy) and updates height and depth. The width does not change.
    pub fn place(&mut self, other: &MathBox, dx: f32, dy: f32) {
        for item in &other.items {
            let mut i = item.clone();
            i.shift(dx, dy);
            self.items.push(i);
        }
        if !other.items.is_empty() || other.height > 0.0 || other.depth > 0.0 {
            self.height = self.height.max(other.height + dy);
            self.depth = self.depth.max(other.depth - dy);
        }
        self.single_glyph = false;
    }

    /// Appends `other` on the right, on the same baseline.
    pub fn append(&mut self, other: &MathBox) {
        let x = self.width;
        self.place(other, x, 0.0);
        self.width += other.width;
        self.italic = other.italic;
    }

    pub fn shift_vertical(&mut self, dy: f32) {
        for item in &mut self.items {
            item.shift(0.0, dy);
        }
        self.height += dy;
        self.depth -= dy;
    }

    /// Multiplies everything by `f`, from the origin (`\scalebox`).
    pub fn scale_box(&mut self, f: f32) {
        for item in &mut self.items {
            match item {
                Item::Glyph { x, y, scale, .. } => {
                    *x *= f;
                    *y *= f;
                    *scale *= f;
                }
                Item::Rule { x, y, width, height, .. } => {
                    *x *= f;
                    *y *= f;
                    *width *= f;
                    *height *= f;
                }
                Item::Line { x1, y1, x2, y2, thickness, .. } => {
                    *x1 *= f;
                    *y1 *= f;
                    *x2 *= f;
                    *y2 *= f;
                    *thickness *= f;
                }
                Item::Ellipse { cx, cy, rx, ry, thickness, .. } => {
                    *cx *= f;
                    *cy *= f;
                    *rx *= f;
                    *ry *= f;
                    *thickness *= f;
                }
            }
        }
        self.width *= f;
        self.height *= f;
        self.depth *= f;
        self.italic *= f;
        self.accent_point = self.accent_point.map(|p| p * f);
        self.single_glyph = false;
    }

    pub fn colorize(&mut self, color: &str) {
        for item in &mut self.items {
            item.colorize(color);
        }
    }

    pub fn total(&self) -> f32 {
        self.height + self.depth
    }
}