Function convexHull

packages/react-aria/src/tooltip/useSafeArea.ts:123–152

(points: Point[])

// Computes the convex hull of a set of points using the monotone chain algorithm.
function convexHull(points: Point[]): Point[] {
  let sorted = points.slice().sort((a, b) => a.x - b.x || a.y - b.y);
  if (sorted.length < 3) {
    return sorted;
  }

  let cross = (o: Point, a: Point, b: Point) =>
    (a.x - o.x) * (b.y - o.y) - (a.y - o.y) * (b.x - o.x);

  let lower: Point[] = [];
  for (let p of sorted) {
    while (lower.length >= 2 && cross(lower[lower.length - 2], lower[lower.length - 1], p) <= 0) {
      lower.pop();
    }
    lower.push(p);
  }

  let upper: Point[] = [];
  for (let i = sorted.length - 1; i >= 0; i--) {
    let p = sorted[i];
    while (upper.length >= 2 && cross(upper[upper.length - 2], upper[upper.length - 1], p) <= 0) {
      upper.pop();
    }
    upper.push(p);
  }

  lower.pop();
  upper.pop();
  return lower.concat(upper);
}

// Ray casting point-in-polygon test.
function isPointInPolygon(point: Point, polygon: Point[]): boolean {