Class: Item::UpcBarcode

Inherits:
BaseService show all
Defined in:
app/services/item/upc_barcode.rb

Overview

This will generate a UPC or EAN barcode, right now it is fine tuned to print on
30336 compatible Dymo labels (2.125" x 1") - This is paper size 'w72h154' in PrintNode
To make this work you will need a Dymo labelwriter 400 series with the right label and the PrintNode server running

  1. Go to localhost:631, manage printers, select the dymo
  2. Select "Set Default options"
  3. Select Media Size 30336, Continuous paper: false, output resolution 300x600, print quality barcode and graphics, media source auto
  4. In print node options, next to the printer, page width set to 1.0, page height set to 2.13

Defined Under Namespace

Classes: Result

Instance Attribute Summary

Attributes inherited from BaseService

#options

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from BaseService

#initialize, #log_debug, #log_error, #log_info, #log_warning, #logger, #tagged_logger

Constructor Details

This class inherits a constructor from BaseService

Class Method Details

.gtin_checksum(data_digits) ⇒ Object

Mod-10 GTIN check digit: weight 3,1 alternating from the rightmost data
digit. Replaces Barby::EAN13/UPCA#checksum (zint appends the check digit
when encoding but doesn't expose it as a query).



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# File 'app/services/item/upc_barcode.rb', line 79

def self.gtin_checksum(data_digits)
  sum = data_digits.reverse.chars.each_with_index.sum { |d, i| d.to_i * (i.even? ? 3 : 1) }
  (10 - (sum % 10)) % 10
end

.identify_type(gtin) ⇒ Object 



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# File 'app/services/item/upc_barcode.rb', line 64

def self.identify_type(gtin)
  return :invalid unless gtin.match?(/\A\d+\z/) # barby rejected non-numeric data; keep that

  if gtin.size == 13 && gtin_checksum(gtin.first(12)) == gtin.last.to_i
    :gtin13
  elsif gtin.size == 12 && gtin_checksum(gtin.first(11)) == gtin.last.to_i
    :gtin12
  else
    :invalid
  end
end

Instance Method Details

#process(gtin, _identifier: nil, file_path: nil, output_format: nil, force_ean_format: false) ⇒ Object

force_ean_format will force an ean barcode output (13 digits) 1,6,6 even for UPC (basically prepending a zero)
http://www.officialeancode.com/spanish/ean-guide/gtin-13-barcode.html



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# File 'app/services/item/upc_barcode.rb', line 18

def process(gtin, _identifier: nil, file_path: nil, output_format: nil, force_ean_format: false)
  require 'zint'

  output_format ||= :png
  identifier_type ||= :upc

  raise "Unsupported format: #{output_format}, only png supported at this time" unless output_format == :png

  # zint computes and appends the check digit from the 12/11 data digits,
  # exactly as barby did.
  if gtin.size == 13
    identifier_formatted = gtin
    symbology = Zint::Constants::Symbologies::BARCODE_EANX
    data = gtin.first(12)
    identifier_type = :ean
  elsif gtin.size == 12
    if force_ean_format
      identifier_formatted = "0#{gtin}"
      symbology = Zint::Constants::Symbologies::BARCODE_EANX
      data = identifier_formatted.first(12)
      identifier_type = :ean
    else
      identifier_formatted = gtin
      symbology = Zint::Constants::Symbologies::BARCODE_UPCA
      data = gtin.first(11)
    end
  else
    raise 'Invalid gtin format neither 12 nor 13 long'
  end

  barcode = Zint::Barcode.new(value: data, symbology:)
  barcode.scale = 2
  barcode.show_hrt = 0 # barby rendered bars only; keep it that way

  barcode_output = barcode.to_memory_file(extension: '.png')

  return Result.new(output: barcode_output, identifier_type:, identifier_formatted:) unless file_path

  File.open(file_path, 'wb') do |f|
    f.write barcode_output
    f.flush
    f.fsync
  end
  Result.new(output: file_path, identifier_type:, identifier_formatted:)
end