# File lib/pdf/writer.rb, line 663
663:   def viewer_preferences(label, value = 0)
664:     @catalog.viewer_preferences ||= PDF::Writer::Object::ViewerPreferences.new(self)
665: 
666:       # This will only work if the label is one of the valid ones.
667:     if label.kind_of?(Hash)
668:       label.each { |kk, vv| @catalog.viewer_preferences.__send__("#{kk.downcase}=".intern, vv) }
669:     else
670:       @catalog.viewer_preferences.__send__("#{label.downcase}=".intern, value)
671:     end
672:   end