class Magick::RVG::Image

def align_to_viewport(scale)
  tx = case @align
      when 'none', /\AxMin/
        0
      when NilClass, /\AxMid/
        (@width - @image.columns*scale) / 2.0
      when /\AxMax/
        @width - @image.columns*scale
  end
  ty = case @align
      when 'none', /YMin\z/
        0
      when NilClass, /YMid\z/
        (@height - @image.rows*scale) / 2.0
      when /YMax\z/
        @height - @image.rows*scale
  end
  [tx, ty]
end