Function updateBinnedReadout

examples/scatter-density-1m/main.ts:139–157

()

  let lastBinnedText = '';
  let lastUpdateMs = 0;
  const updateBinnedReadout = (): void => {
    const zoom = chart.getZoomRange();
    const startPct = Math.max(0, Math.min(100, zoom?.start ?? 0));
    const endPct = Math.max(0, Math.min(100, zoom?.end ?? 100));
    const a = Math.min(startPct, endPct) / 100;
    const b = Math.max(startPct, endPct) / 100;

    const visibleXMin = xMin + a * xSpan;
    const visibleXMax = xMin + b * xSpan;
    const i0 = lowerBoundByX(points, visibleXMin);
    const i1 = upperBoundByX(points, visibleXMax);
    const visibleCount = Math.max(0, i1 - i0);

    const text = fmt.format(visibleCount);
    if (text !== lastBinnedText) {
      lastBinnedText = text;
      binnedPointsEl.textContent = text;
    }
  };

  // Update frequently while rendering, but throttle DOM writes.
  chart.onPerformanceUpdate(() => {