code: function fullBox(b) {
    if (b.x == null) {
      b.x      = 0
      b.y      = 0
      b.width  = 0
      b.height = 0
    }
  
    b.w  = b.width
    b.h  = b.height
    b.x2 = b.x + b.width
    b.y2 = b.y + b.height
    b.cx = b.x + b.width / 2
    b.cy = b.y + b.height / 2
  
    return b
  }
docs: Add more bounding box properties