calculate_left_margin (SVG::Graph::Graph)

    # File temp/Graph/Graph.rb, line 368
          def calculate_left_margin
            @border_left = 7
            # Check for Y labels
            max_y_label_height_px = rotate_y_labels ?
              y_label_font_size :
              get_y_labels.max{|a,b|
                a.to_s.length<=>b.to_s.length
              }.to_s.length * y_label_font_size * 0.6
            @border_left += max_y_label_height_px if show_y_labels
            @border_left += max_y_label_height_px + 10 if stagger_y_labels
            @border_left += y_title_font_size + 5 if show_y_title
          end