def prepare_chart(index, chart_id, drawing_id) # :nodoc:
      @chart.id = chart_id - 1

      drawing = Drawing.new
      @drawing = drawing
      @drawing.orientation = @page_setup.orientation

      @external_drawing_links << [ '/drawing', "../drawings/drawing#{drawing_id}.xml" ]

      @drawing_links << [ '/chart', "../charts/chart#{chart_id}.xml"]
    end
def prepare_chart(index, chart_id, drawing_id) # :nodoc:
      @chart.id = chart_id - 1

      drawing = Drawing.new
      @drawing = drawing
      @drawing.orientation = @page_setup.orientation

      @external_drawing_links << [ '/drawing', "../drawings/drawing#{drawing_id}.xml" ]

      @drawing_links << [ '/chart', "../charts/chart#{chart_id}.xml"]
    end
Set up chart/drawings.