layout.rs

use ab_glyph::{point, Font, Glyph, Point, ScaleFont};

/// Simple paragraph layout for glyphs into `target`.
/// Starts at position `(0, ascent)`.
///
/// This is for testing and examples.
pub fn layout_paragraph<F, SF>(
    font: SF,
    position: Point,
    max_width: f32,
    text: &str,
    target: &mut Vec<Glyph>,
) where
    F: Font,
    SF: ScaleFont<F>,
{
    let v_advance = font.height() + font.line_gap();
    let mut caret = position + point(0.0, font.ascent());
    let mut last_glyph: Option<Glyph> = None;
    for c in text.chars() {
        if c.is_control() {
            if c == '\n' {
                caret = point(position.x, caret.y + v_advance);
                last_glyph = None;
            }
            continue;
        }
        let mut glyph = font.scaled_glyph(c);
        if let Some(previous) = last_glyph.take() {
            caret.x += font.kern(previous.id, glyph.id);
        }
        glyph.position = caret;

        last_glyph = Some(glyph.clone());
        caret.x += font.h_advance(glyph.id);

        if !c.is_whitespace() && caret.x > position.x + max_width {
            caret = point(position.x, caret.y + v_advance);
            glyph.position = caret;
            last_glyph = None;
        }

        target.push(glyph);
    }
}