navigo 0.3.1

Simply manipulate GPS/geospatial data in Rust — distances, elevation, simplification, climb detection.
Documentation
import init, { buildTrace } from "../pkg/navigo.js";
import { generateAlpineRoute } from "./sample-trace.js";

// ── Bootstrap ─────────────────────────────────────────────────────────────────

await init();

const pts = generateAlpineRoute();
const trace = buildTrace(pts);

// Cache all bulk arrays once — each getter copies WASM→JS heap.
const locsFlat = trace.locations_flat;
const dists = trace.cumulative_distances;
const gains = trace.cumulative_elevation_gains;
const losses = trace.cumulative_elevation_losses;
const peaks = trace.peaks;
const valleys = trace.valleys;
const climbs = trace.climbs();
const area = trace.area();

// ── Stats cards ───────────────────────────────────────────────────────────────

setText("stat-distance", trace.total_distance.toFixed(1) + " km");
setText("stat-gain", "+" + Math.round(trace.total_elevation_gain) + " m");
setText("stat-loss", "" + Math.round(trace.total_elevation_loss) + " m");
setText("stat-locations", trace.location_count.toString());
setText("stat-climbs", climbs.length.toString());

if (area) {
  setText(
    "stat-bbox",
    `${area.min_latitude.toFixed(3)}°N  ${area.max_latitude.toFixed(3)}°N, ` +
      `${area.min_longitude.toFixed(3)}°E  ${area.max_longitude.toFixed(3)}°E`,
  );
}

// ── Elevation profile ─────────────────────────────────────────────────────────

const canvas = document.getElementById("profile");
drawProfile(canvas, locsFlat, dists, peaks, valleys, climbs);
window.addEventListener("resize", () =>
  drawProfile(canvas, locsFlat, dists, peaks, valleys, climbs),
);

// ── Climbs list ───────────────────────────────────────────────────────────────

renderClimbs(climbs);

// ── Free WASM memory — all data already copied to JS ─────────────────────────
trace.free();

// ── Helpers ───────────────────────────────────────────────────────────────────

function setText(id, text) {
  const el = document.getElementById(id);
  if (el) el.textContent = text;
}

function drawProfile(canvas, locsFlat, dists, peaks, valleys, climbs) {
  const DPR = window.devicePixelRatio || 1;
  const W = canvas.parentElement.clientWidth;
  const H = 260;
  canvas.style.width = W + "px";
  canvas.style.height = H + "px";
  canvas.width = W * DPR;
  canvas.height = H * DPR;

  const ctx = canvas.getContext("2d");
  ctx.scale(DPR, DPR);

  const PAD = { top: 20, right: 20, bottom: 40, left: 64 };
  const CW = W - PAD.left - PAD.right;
  const CH = H - PAD.top - PAD.bottom;

  // Extract altitudes
  const alts = [];
  for (let i = 2; i < locsFlat.length; i += 3) alts.push(locsFlat[i]);

  const maxDist = dists[dists.length - 1];
  const minAlt = Math.min(...alts) - 80;
  const maxAlt = Math.max(...alts) + 80;

  const xP = (d) => PAD.left + (d / maxDist) * CW;
  const yP = (a) => PAD.top + (1 - (a - minAlt) / (maxAlt - minAlt)) * CH;

  // ── White background
  ctx.fillStyle = "#fff";
  ctx.fillRect(0, 0, W, H);

  // ── Yellow climb zones (behind everything)
  climbs.forEach((c) => {
    ctx.fillStyle = "#ffe000";
    const x1 = xP(c.start_dist_km);
    const x2 = xP(c.start_dist_km + c.climb_dist_km);
    ctx.fillRect(x1, PAD.top, x2 - x1, CH);
  });

  // ── Horizontal gridlines
  const altStep = 200;
  ctx.strokeStyle = "rgba(0,0,0,0.08)";
  ctx.lineWidth = 1;
  for (
    let a = Math.ceil(minAlt / altStep) * altStep;
    a <= maxAlt;
    a += altStep
  ) {
    const y = yP(a);
    if (y < PAD.top || y > H - PAD.bottom) continue;
    ctx.beginPath();
    ctx.moveTo(PAD.left, y);
    ctx.lineTo(W - PAD.right, y);
    ctx.stroke();
  }

  // ── Solid black elevation fill
  ctx.beginPath();
  ctx.moveTo(xP(dists[0]), yP(alts[0]));
  for (let i = 1; i < dists.length; i++) ctx.lineTo(xP(dists[i]), yP(alts[i]));
  ctx.lineTo(xP(maxDist), H - PAD.bottom);
  ctx.lineTo(xP(0), H - PAD.bottom);
  ctx.closePath();
  ctx.fillStyle = "#000";
  ctx.fill();

  // ── Valley dots (white circle, black outline)
  Array.from(valleys).forEach((idx) => {
    ctx.beginPath();
    ctx.arc(xP(dists[idx]), yP(alts[idx]), 5, 0, Math.PI * 2);
    ctx.fillStyle = "#fff";
    ctx.strokeStyle = "#000";
    ctx.lineWidth = 2;
    ctx.fill();
    ctx.stroke();
  });

  // ── Peak dots (solid red)
  Array.from(peaks).forEach((idx) => {
    ctx.beginPath();
    ctx.arc(xP(dists[idx]), yP(alts[idx]), 5, 0, Math.PI * 2);
    ctx.fillStyle = "#ff2800";
    ctx.fill();
  });

  // ── Axes (thick black)
  ctx.strokeStyle = "#000";
  ctx.lineWidth = 2;
  ctx.beginPath();
  ctx.moveTo(PAD.left, PAD.top);
  ctx.lineTo(PAD.left, H - PAD.bottom);
  ctx.lineTo(W - PAD.right, H - PAD.bottom);
  ctx.stroke();

  // ── Y labels + ticks
  ctx.fillStyle = "#000";
  ctx.font = "bold 10px Courier New, monospace";
  ctx.textAlign = "right";
  ctx.textBaseline = "middle";
  for (
    let a = Math.ceil(minAlt / altStep) * altStep;
    a <= maxAlt;
    a += altStep
  ) {
    const y = yP(a);
    if (y < PAD.top || y > H - PAD.bottom) continue;
    ctx.fillText(a + "m", PAD.left - 6, y);
    ctx.beginPath();
    ctx.moveTo(PAD.left - 4, y);
    ctx.lineTo(PAD.left, y);
    ctx.lineWidth = 1.5;
    ctx.stroke();
  }

  // ── X labels + ticks
  ctx.textAlign = "center";
  ctx.textBaseline = "top";
  for (let d = 0; d <= maxDist; d += 5) {
    const x = xP(d);
    ctx.fillText(d + "km", x, H - PAD.bottom + 6);
    ctx.beginPath();
    ctx.moveTo(x, H - PAD.bottom);
    ctx.lineTo(x, H - PAD.bottom + 4);
    ctx.lineWidth = 1.5;
    ctx.stroke();
  }

  // ── Climb gradient labels (on the yellow bands, above the black fill)
  ctx.textAlign = "center";
  ctx.textBaseline = "bottom";
  ctx.font = "bold 10px Courier New, monospace";
  climbs.forEach((c) => {
    const midX = xP(c.start_dist_km + c.climb_dist_km / 2);
    ctx.fillStyle = "#000";
    ctx.fillText(` ${c.avg_gradient.toFixed(1)}%`, midX, H - PAD.bottom - 4);
  });
}

function renderClimbs(climbs) {
  const el = document.getElementById("climbs-list");
  if (!el) return;

  if (climbs.length === 0) {
    el.innerHTML = '<p class="empty">NO QUALIFYING CLIMBS DETECTED.</p>';
    return;
  }

  el.innerHTML = climbs
    .map(
      (c, i) => `
    <div class="climb-card">
      <div class="climb-rank">#${String(i + 1).padStart(2, "0")}</div>
      <div class="climb-metrics">
        <div class="metric">
          <span class="label">dist</span>
          <span class="val">${c.climb_dist_km.toFixed(1)}<small>km</small></span>
        </div>
        <div class="metric">
          <span class="label">gain</span>
          <span class="val">+${Math.round(c.elevation_gain)}<small>m</small></span>
        </div>
        <div class="metric">
          <span class="label">grade</span>
          <span class="val">${c.avg_gradient.toFixed(1)}<small>%</small></span>
        </div>
        <div class="metric">
          <span class="label">summit</span>
          <span class="val">${Math.round(c.summit_elev)}<small>m</small></span>
        </div>
        <div class="metric score">
          <span class="label">score</span>
          <span class="val">${(c.climb_dist_km * c.avg_gradient).toFixed(0)}</span>
        </div>
      </div>
    </div>
  `,
    )
    .join("");
}