oak-gpui/crates/gpui2/src/text_system/line.rs

use crate::{
    black, point, px, size, BorrowWindow, Bounds, Hsla, Pixels, Point, Result, Size,
    UnderlineStyle, WindowContext, WrapBoundary, WrappedLineLayout,
};
use smallvec::SmallVec;
use std::sync::Arc;

#[derive(Debug, Clone)]
pub struct DecorationRun {
    pub len: u32,
    pub color: Hsla,
    pub underline: Option<UnderlineStyle>,
}

#[derive(Clone, Default, Debug)]
pub struct Line {
    pub(crate) layout: Arc<WrappedLineLayout>,
    pub(crate) decorations: SmallVec<[DecorationRun; 32]>,
}

impl Line {
    pub fn size(&self, line_height: Pixels) -> Size<Pixels> {
        size(
            self.layout.width,
            line_height * (self.layout.wrap_boundaries.len() + 1),
        )
    }

    pub fn wrap_count(&self) -> usize {
        self.layout.wrap_boundaries.len()
    }

    pub fn paint(
        &self,
        origin: Point<Pixels>,
        line_height: Pixels,
        cx: &mut WindowContext,
    ) -> Result<()> {
        let padding_top =
            (line_height - self.layout.layout.ascent - self.layout.layout.descent) / 2.;
        let baseline_offset = point(px(0.), padding_top + self.layout.layout.ascent);

        let mut style_runs = self.decorations.iter();
        let mut wraps = self.layout.wrap_boundaries.iter().peekable();
        let mut run_end = 0;
        let mut color = black();
        let mut current_underline: Option<(Point<Pixels>, UnderlineStyle)> = None;
        let text_system = cx.text_system().clone();

        let mut glyph_origin = origin;
        let mut prev_glyph_position = Point::default();
        for (run_ix, run) in self.layout.layout.runs.iter().enumerate() {
            let max_glyph_size = text_system
                .bounding_box(run.font_id, self.layout.layout.font_size)?
                .size;

            for (glyph_ix, glyph) in run.glyphs.iter().enumerate() {
                glyph_origin.x += glyph.position.x - prev_glyph_position.x;

                if wraps.peek() == Some(&&WrapBoundary { run_ix, glyph_ix }) {
                    wraps.next();
                    if let Some((underline_origin, underline_style)) = current_underline.take() {
                        cx.paint_underline(
                            underline_origin,
                            glyph_origin.x - underline_origin.x,
                            &underline_style,
                        )?;
                    }

                    glyph_origin.x = origin.x;
                    glyph_origin.y += line_height;
                }
                prev_glyph_position = glyph.position;
                let glyph_origin = glyph_origin + baseline_offset;

                let mut finished_underline: Option<(Point<Pixels>, UnderlineStyle)> = None;
                if glyph.index >= run_end {
                    if let Some(style_run) = style_runs.next() {
                        if let Some((_, underline_style)) = &mut current_underline {
                            if style_run.underline.as_ref() != Some(underline_style) {
                                finished_underline = current_underline.take();
                            }
                        }
                        if let Some(run_underline) = style_run.underline.as_ref() {
                            current_underline.get_or_insert((
                                point(
                                    glyph_origin.x,
                                    origin.y
                                        + baseline_offset.y
                                        + (self.layout.layout.descent * 0.618),
                                ),
                                UnderlineStyle {
                                    color: Some(run_underline.color.unwrap_or(style_run.color)),
                                    thickness: run_underline.thickness,
                                    wavy: run_underline.wavy,
                                },
                            ));
                        }

                        run_end += style_run.len as usize;
                        color = style_run.color;
                    } else {
                        run_end = self.layout.text.len();
                        finished_underline = current_underline.take();
                    }
                }

                if let Some((underline_origin, underline_style)) = finished_underline {
                    cx.paint_underline(
                        underline_origin,
                        glyph_origin.x - underline_origin.x,
                        &underline_style,
                    )?;
                }

                let max_glyph_bounds = Bounds {
                    origin: glyph_origin,
                    size: max_glyph_size,
                };

                let content_mask = cx.content_mask();
                if max_glyph_bounds.intersects(&content_mask.bounds) {
                    if glyph.is_emoji {
                        cx.paint_emoji(
                            glyph_origin,
                            run.font_id,
                            glyph.id,
                            self.layout.layout.font_size,
                        )?;
                    } else {
                        cx.paint_glyph(
                            glyph_origin,
                            run.font_id,
                            glyph.id,
                            self.layout.layout.font_size,
                            color,
                        )?;
                    }
                }
            }
        }

        if let Some((underline_start, underline_style)) = current_underline.take() {
            let line_end_x = origin.x + self.layout.layout.width;
            cx.paint_underline(
                underline_start,
                line_end_x - underline_start.x,
                &underline_style,
            )?;
        }

        Ok(())
    }
}