ced/src/ui/central_panel/find_highlight.rs

use eframe::egui;

pub(super) fn _draw_find_highlight(
    ui: &mut egui::Ui,
    content: &str,
    start_pos: usize,
    end_pos: usize,
    editor_rect: egui::Rect,
    font_size: f32,
) {
    let font_id = ui
        .style()
        .text_styles
        .get(&egui::TextStyle::Monospace)
        .unwrap_or(&egui::FontId::monospace(font_size))
        .clone();

    let text_up_to_start = &content[..start_pos.min(content.len())];

    let start_line = text_up_to_start.chars().filter(|&c| c == '\n').count();

    let line_start_byte_pos = text_up_to_start.rfind('\n').map(|pos| pos + 1).unwrap_or(0);
    let line_start_char_pos = content[..line_start_byte_pos].chars().count();
    let start_char_pos = content[..start_pos].chars().count();
    let start_col = start_char_pos - line_start_char_pos;

    let lines: Vec<&str> = content.lines().collect();
    if start_line >= lines.len() {
        return;
    }

    let line_text = lines[start_line];
    let text_before_match: String = line_text.chars().take(start_col).collect();

    let line_height = ui.fonts(|fonts| fonts.row_height(&font_id));

    let horizontal_margin = ui.spacing().button_padding.x - 4.0;
    let vertical_margin = ui.spacing().button_padding.y - 1.0;
    let text_area_left = editor_rect.left() + horizontal_margin;
    let text_area_top = editor_rect.top() + vertical_margin;

    let text_before_width = ui.fonts(|fonts| {
        fonts
            .layout(
                text_before_match,
                font_id.clone(),
                egui::Color32::WHITE,
                f32::INFINITY,
            )
            .size()
            .x
    });

    let start_y = text_area_top + (start_line as f32 * line_height);
    let start_x = text_area_left + text_before_width;

    {
        let match_text = &content[start_pos..end_pos.min(content.len())];

        let match_width = ui.fonts(|fonts| {
            fonts
                .layout(
                    match_text.to_string(),
                    font_id.clone(),
                    ui.visuals().text_color(),
                    f32::INFINITY,
                )
                .size()
                .x
        });

        let highlight_rect = egui::Rect::from_min_size(
            egui::pos2(start_x, start_y),
            egui::vec2(match_width, line_height),
        );

        ui.painter()
            .rect_filled(highlight_rect, 0.0, ui.visuals().selection.bg_fill);
    }
}