Function computeDraftPosition

packages/sdk/src/adapters/iframe.ts:79–88

(
  dataX: string | null,
  dataY: string | null,
  dx: number,
  dy: number,
)

 * `data-x` / `data-y` default to 0 when absent or non-numeric.
 */
export function computeDraftPosition(
  dataX: string | null,
  dataY: string | null,
  dx: number,
  dy: number,
): { x: number; y: number } {
  const baseX = parseFloat(dataX ?? "0") || 0;
  const baseY = parseFloat(dataY ?? "0") || 0;
  return { x: baseX + dx, y: baseY + dy };
}

// ─── Image-alpha pure helpers (WS-G phase 1) ──────────────────────────────────