public static Rectangle[] InflateRectangles(Rectangle[] rects, int len)
{
Rectangle[] inflated = new Rectangle[rects.Length];
for (int i = 0; i < rects.Length; ++i)
inflated[i] = new Rectangle(rects[i].X-len, rects[i].Y-len, rects[i].Width + 2 * len, rects[i].Height + 2 * len);
return inflated;
}