DndGamePlayer/app/shared/geometry/fitAspectRect.ts

/** Вписать прямоугольник целевого аспекта в бокс (как object-fit: contain). */
export function fitAspectRect(
  boxW: number,
  boxH: number,
  aspectW: number,
  aspectH: number,
): { x: number; y: number; w: number; h: number } {
  const bw = Math.max(1, boxW);
  const bh = Math.max(1, boxH);
  const aw = Math.max(1, aspectW);
  const ah = Math.max(1, aspectH);
  const boxAspect = bw / bh;
  const targetAspect = aw / ah;
  if (boxAspect > targetAspect) {
    const h = bh;
    const w = h * targetAspect;
    return { x: (bw - w) / 2, y: 0, w, h };
  }
  const w = bw;
  const h = w / targetAspect;
  return { x: 0, y: (bh - h) / 2, w, h };
}