igv-rs 0.7.0

Interactive terminal genome viewer for FASTA / VCF / BAM / GFF / BED / bigWig / BEDPE. Includes a bundled-igv.js browser companion.
Documentation 
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use ratatui::buffer::Buffer;
use ratatui::layout::Rect;
use ratatui::widgets::{Block, Borders, Widget};

use igv_core::coverage;
use igv_core::region::genomic_to_screen;
use igv_core::render::RenderMode;

use crate::app::state::AppState;
use crate::ui::theme::Theme;

pub struct CoverageWidget<'a> {
    pub state: &'a AppState,
    pub theme: &'a Theme,
}

impl Widget for CoverageWidget<'_> {
    fn render(self, area: Rect, buf: &mut Buffer) {
        let region = &self.state.region;
        let bams_present = !self.state.bams.is_empty();
        // BAM rows are only fetched at PerBase / DetailedReads zoom levels
        // (see `Loader::dispatch`). Beyond that, `region.width()` may be in
        // the hundreds of millions and an `O(width)` allocation here would
        // exceed any reasonable memory budget. The widget renders only its
        // title in those modes — the footer already calls out that reads /
        // coverage are hidden at wide zoom.
        let mode = self.state.thresholds.classify(region.width());
        let coverage_active = bams_present
            && matches!(mode, RenderMode::PerBase | RenderMode::DetailedReads);

        // Compute summed depth across BAM tracks up-front so the title can
        // include the observed max ("[0-N]"), matching IGV's y-axis label.
        let mut summed: Vec<u32> = Vec::new();
        let mut max_depth: u32 = 0;
        if coverage_active {
            summed = vec![0u32; region.width() as usize];
            for rows in &self.state.bam_rows {
                let cov = coverage::compute(rows, region.start, region.end);
                for (i, d) in cov.depths.iter().enumerate() {
                    summed[i] = summed[i].saturating_add(*d);
                }
            }
            max_depth = summed.iter().copied().max().unwrap_or(0);
        }

        let title = if coverage_active {
            format!("coverage [0-{}]", max_depth)
        } else if bams_present {
            "coverage (zoomed out)".to_string()
        } else {
            "coverage".to_string()
        };
        let block = Block::default()
            .borders(Borders::TOP | Borders::BOTTOM)
            .style(self.theme.get("BORDER"))
            .title(title);
        let inner = block.inner(area);
        block.render(area, buf);
        if inner.area() == 0 || !coverage_active {
            return;
        }

        let scale = max_depth.max(1) as f32;
        let style = self.theme.get("COVERAGE");
        let height = inner.height as usize;
        for (i, &d) in summed.iter().enumerate() {
            let g = (region.start - 1) + i as u64;
            let col = match genomic_to_screen(g, region.start - 1, region.width(), inner.width as u32) {
                Some(c) => c,
                None => continue,
            };
            let bar_h = ((d as f32 / scale) * height as f32).ceil() as u16;
            for row in 0..bar_h.min(inner.height) {
                let y = inner.y + inner.height.saturating_sub(1) - row;
                buf[(inner.x + col as u16, y)]
                    .set_char('█')
                    .set_style(style);
            }
        }
    }
}