# File lib/gruff/side_bar.rb, line 68
  def draw
    @has_left_labels = true
    super

    return unless @has_data

    # Setup spacing.
    #
    # Columns sit stacked.
    spacing_factor = 0.9

    @bar_width = @graph_height / @column_count.to_f
    @d         = @d.stroke_opacity 0.0
    height     = Array.new(@column_count, 0)
    length     = Array.new(@column_count, @graph_left)

    @norm_data.each_with_index do |data_row, row_index|
      @d = @d.fill data_row[DATA_COLOR_INDEX]

      data_row[1].each_with_index do |data_point, point_index|

          # Using the original calcs from the stacked bar chart 
          # to get the difference between
          # part of the bart chart we wish to stack.
        temp1      = @graph_left + (@graph_width -
                                data_point * @graph_width - 
                                height[point_index]) + 1
        temp2      = @graph_left + @graph_width - height[point_index] - 1
        difference = temp2 - temp1

        left_x                = length[point_index] #+ 1
        left_y                = @graph_top + (@bar_width * point_index)
        right_x               = left_x + difference
        right_y               = left_y + @bar_width * spacing_factor
        length[point_index] += difference
        height[point_index] += (data_point * @graph_width - 2)

        @d                    = @d.rectangle(left_x, left_y, right_x, right_y)

        # Calculate center based on bar_width and current row
        label_center          = @graph_top + (@bar_width * point_index) + (@bar_width * spacing_factor / 2.0)
        draw_label(label_center, point_index)
      end

    end

    @d.draw(@base_image)    
  end