module Magick::RVG::PreserveAspectRatio

def preserve_aspect_ratio(align, meet_or_slice = 'meet')

[+meet_or_slice+] one of 'meet' or 'slice'
'YMin', 'YMid', or 'YMax'
[+align+] a combination of 'xMin', 'xMid', or 'xMax', followed by
Specifies how the image within a viewport should be scaled.
++
Included in Stretchable module and Image class
-- 
def preserve_aspect_ratio(align, meet_or_slice = 'meet')
  @align = align.to_s
  if @align != 'none'
    m = /\A(xMin|xMid|xMax)(YMin|YMid|YMax)\z/.match(@align)
    raise(ArgumentError, "unknown alignment specifier: #{@align}") unless m
  end
  if meet_or_slice
    meet_or_slice = meet_or_slice.to_s.downcase
    raise(ArgumentError, "specifier must be `meet' or `slice' (got #{meet_or_slice})") unless %w[meet slice].include?(meet_or_slice)
    @meet_or_slice = meet_or_slice
  end
  yield(self) if block_given?
  self
end