    # File lib/rvg/stretchable.rb, line 17
                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
                        if meet_or_slice == 'meet' || meet_or_slice == 'slice'
                            @meet_or_slice = meet_or_slice
                        else
                            raise(ArgumentError, "specifier must be `meet' or `slice' (got #{meet_or_slice})")
                        end
                    end
                    yield(self) if block_given?
                    self
                end