code: def calculate_size(self, modules_per_line, number_of_lines, dpi=300):
          
          width = 2 * self.quiet_zone + modules_per_line * self.module_width
          height = 2.0 + self.module_height * number_of_lines
          if self.font_size and self.text:
              height += pt2mm(self.font_size) / 2 + self.text_distance
          return int(mm2px(width, dpi)), int(mm2px(height, dpi))
docs: Calculates the size of the barcode in pixel.
  
          :parameters:
              modules_per_line : Integer
                  Number of modules in one line.
              number_of_lines : Integer
                  Number of lines of the barcode.
              dpi : Integer
                  DPI to calculate.
  
          :returns: Width and height of the barcode in pixel.
          :rtype: Tuple