def prefix(fonts, colours)
         text = StringIO.new

         text << "\\#{@justification.id2name}"
         text << "\\li#{@left_indent}"        unless @left_indent.nil?
         text << "\\ri#{@right_indent}"       unless @right_indent.nil?
         text << "\\fi#{@first_line_indent}"  unless @first_line_indent.nil?
         text << "\\sb#{@space_before}"       unless @space_before.nil?
         text << "\\sa#{@space_after}"        unless @space_after.nil?
         text << "\\sl#{@line_spacing}"       unless @line_spacing.nil?
         text << '\rtlpar' if @flow == RIGHT_TO_LEFT

         text.string.length > 0 ? text.string : nil
      end
def prefix(fonts, colours)
         text = StringIO.new

         text << "\\#{@justification.id2name}"
         text << "\\li#{@left_indent}"        unless @left_indent.nil?
         text << "\\ri#{@right_indent}"       unless @right_indent.nil?
         text << "\\fi#{@first_line_indent}"  unless @first_line_indent.nil?
         text << "\\sb#{@space_before}"       unless @space_before.nil?
         text << "\\sa#{@space_after}"        unless @space_after.nil?
         text << "\\sl#{@line_spacing}"       unless @line_spacing.nil?
         text << '\rtlpar' if @flow == RIGHT_TO_LEFT

         text.string.length > 0 ? text.string : nil
      end
This method generates a string containing the prefix associated with a
 style object.

 ==== Parameters
 fonts::    A reference to a FontTable containing any fonts used by the
            style (may be nil if no fonts used).
 colours::  A reference to a ColourTable containing any colours used by
            the style (may be nil if no colours used).