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
       else
         0
       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
       else
         0
       end
  [tx, ty]
end