Function normalizeWheelDelta

src/interaction/createInsideZoom.ts:12–27

(e: WheelEvent, basisCssPx: number)

const clamp = (v: number, lo: number, hi: number): number => Math.min(hi, Math.max(lo, v));

const normalizeWheelDelta = (e: WheelEvent, basisCssPx: number): number => {
  const raw = e.deltaY;
  if (!Number.isFinite(raw) || raw === 0) return 0;

  // Normalize to CSS pixels-ish so sensitivity is stable across deltaMode.
  switch (e.deltaMode) {
    case WheelEvent.DOM_DELTA_PIXEL:
      return raw;
    case WheelEvent.DOM_DELTA_LINE:
      return raw * 16;
    case WheelEvent.DOM_DELTA_PAGE:
      return raw * (Number.isFinite(basisCssPx) && basisCssPx > 0 ? basisCssPx : 800);
    default:
      return raw;
  }
};

const normalizeWheelDeltaX = (e: WheelEvent, basisCssPx: number): number => {
  const raw = e.deltaX;