viewer_preferences (PDF::Writer)

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