ScaleDown

def scale_down(iw, ih, dw, dh)

  # 1. determining which dimension is the one that needs to be
  # scaled the most
  limiting_dim = (iw / ih) > (dw / dh) ? "width" : "height"
  
  # 2. then figure out how much that scaling actually is
  if limiting dim == "width"
    scale_by = dw / iw
  else
    scale_by = dh / ih
  end
    
  # 3. apply the scaling factor to both dimensions
  return [iw*scale_by, ih*scale_by]
end

def find_scale_pair(iw, ih, dw, dh)

  # 1. determining which dimension is the one that needs to be
  # scaled the most
  limiting_dim = (iw / ih) > (dw / dh) ? "width" : "height"
  
  # 2. return the non-limiting dimension's desired value
  # and -1 for the limiting dimension
  if limiting_dim == "width"
    return [-1, dh]
  else
    return [dw, -1]
  end
end