Function computeVisibleXDomain

src/core/createRenderCoordinator.ts:1287–1304

(
  baseXDomain: { readonly min: number; readonly max: number },
  zoomRange?: ZoomRange | null
)

};

const computeVisibleXDomain = (
  baseXDomain: { readonly min: number; readonly max: number },
  zoomRange?: ZoomRange | null
): { readonly min: number; readonly max: number; readonly spanFraction: number } => {
  if (!zoomRange) return { ...baseXDomain, spanFraction: 1 };
  const span = baseXDomain.max - baseXDomain.min;
  if (!Number.isFinite(span) || span === 0) return { ...baseXDomain, spanFraction: 1 };

  const start = zoomRange.start;
  const end = zoomRange.end;
  const xMin = baseXDomain.min + (start / 100) * span;
  const xMax = baseXDomain.min + (end / 100) * span;
  const normalized = normalizeDomain(xMin, xMax);

  const fractionRaw = (end - start) / 100;
  const spanFraction = Number.isFinite(fractionRaw) ? Math.max(0, Math.min(1, fractionRaw)) : 1;
  return { min: normalized.min, max: normalized.max, spanFraction };
};

type IntroPhase = 'pending' | 'running' | 'done';