This is a gem based on a terrific older gem by Cassio Marques. Although the new printers are mostly compatible with old Eltron (Epl) code, my needs require many of the new Zebra (ZPL) functions.

Zebra::Zpl

ToDo: Update documentation with instructions for new features such as font sizing, margins, and text alignment

Zebra::Zpl offers a Ruby DSL to design and print labels using the ZPL programming language.

Installation

Add this line to your application's Gemfile:

gem 'zebra-zpl'

And then execute:

$ bundle

Or install it yourself as:

$ gem install zebra-zpl

Usage

Building labels

You create new labels with an instance of the Zebra::Zpl::Label class. It accepts the following options:

• copies: The number of copies to print. This option defaults to 1.
• width: The label's width, in dots.
• length: The label's length, is dots.
• gap: The gap between labels, in dots.
• print_speed: The print speed to be used. You can use values between 0 and 6. This option is required.
• print_density: The print density to be used. You can use values between 0 and 15. This option is required.

With a label, you can start adding elements to it:

label = Zebra::Zpl::Label.new :print_density => 8, :print_speed => 3
text  = Zebra::Zpl::Text.new :data => "Hello, printer!", :position => [100, 100], :font_size => Zebra::Zpl::FontSize::SIZE_2
label << text

You can add as many elements as you want.

Printing the labels

You need to have your printer visible to CUPS (or shared on the network in Windows). Once your printer is configured and you know its name on CUPS (or the Windows shared printer name), you can send the labels to the printer using a Zebra::PrintJob instance.

label = Zebra::Zpl::Label.new(
  :width         => 200,
  :length        => 200,
  :print_speed   => 3,
  :print_density => 6
)


barcode = Zebra::Zpl::Barcode.new(
  :data                      => "12345678",
  :position                  => [50, 50],
  :height                    => 50,
  :print_human_readable_code => true,
  :narrow_bar_width          => 4,
  :wide_bar_width            => 8,
  :type                      => Zebra::Zpl::BarcodeType::CODE_128_AUTO
)

label << barcode

print_job = Zebra::PrintJob.new "<your-printer-name-on-cups/windows-shared-printer-name>"

print_job.print label

This will persist the label contents to a tempfile (using Ruby's tempfile core library) and copy the file to the printer using either lpr -P <your-printer-name-on-cups> -o raw <path-to-the-temp-file> (if you're on Mac OSX) or lp -d <your-printer-name-on-cups> -o raw <path-to-the-tempfile> (if you're on Linux). All the tempfile creation/path resolution, as well as which command has to be used, are handled by the PrintJob class.

Printing to directly to Windows LPD

This gem also supports printing directly to shared printer on Windows using LPD. In order to print directly to a LPD on a Windows machine you need two things:

• rlpr installed on the (UNIX) system running your app that uses this gem.¹
• LPD Print Service and LPR Port Monitor features enabled on the Windows machine.²

---

1. On a distro such as Ubuntu simply do: sudo apt-get install rlpr
If using OSX then you will have to manually build it from source and add it to your $PATH environment variable.

2. The printer name that you pass in must correspond with the shared printer name on the Windows machine.

Printing QR codes

label = Zebra::Zpl::Label.new(
  :width=>350,
  :length=>250,
  :print_speed=>3,
  :print_density=>6
)

qrcode = Zebra::Zpl::Qrcode.new(
  :data=>"www.github.com",
  :position=>[50,10],
  :scale_factor=>3,
  :correction_level=>"H"
)

label << qrcode

print_job = Zebra::PrintJob.new "your-qr-printer-name-on-cups"

print_job.print label

Available elements

Text

You create text elements to print using instances of the Zebra::Zpl::Text class. It accepts the following options:

• position: An array with the coordinates to place the text, in dots.
• rotation: The rotation for the text. More about the possible values below.
• data: The text to be printed.
• v_multiplier: The vertical multiplier to use.
• h_multiplier: The horizontal multipler to use.
• print_mode: The print mode. Can be normal ("N") or reverse ("R").
• font_size: The font size to use. You can use values between 1 and 5.

For the print modes, you can also use the constants:

• Zebra::Zpl::PrintMode::NORMAL
• Zebra::Zpl::PrintMode::REVERSE

Barcodes

You create barcode elements to print using instances of the Zebra::Zpl::Barcode class. It accepts the following options:

• position: An array with the coordinates to place the text, in dots.
• height: The barcode's height, in dots.
• rotation: The rotation for the text. More about the possible values below.
• data: The text to be printed.
• type: The type os barcode to use. More on the available types below.
• narrow_bar_width: The barcode's narrow bar width, in dots.
• wide_bar_width: The barcode's wide bar width, in dots.
• print_human_readable_code: Can be true or false, indicates if the human readable contents should be printed below the barcode.

The available barcode types are:

• Zebra::Zpl::BarcodeType::CODE_39
• Zebra::Zpl::BarcodeType::CODE_93
• Zebra::Zpl::BarcodeType::CODE_128_AUTO
• Zebra::Zpl::BarcodeType::CODABAR
• Zebra::Zpl::BarcodeType::CODE_AZTEC
• Zebra::Zpl::BarcodeType::CODE_AZTEC_PARAMS
• Zebra::Zpl::BarcodeType::CODE_UPS_MAXICODE
• Zebra::Zpl::BarcodeType::CODE_QR

QR Codes

You can create QR Codes elements to print using instances of the Zebra::Zpl::Qrcode class. It accepts the following options:

• position: An array with the coordinates to place the QR code, in dots.
• scale factor: Crucial variable of the QR codes's size. Accepted values: 1-99.
• error correction level: Algorithm enables reading damaged QR codes. There are four error correction levels: L - 7% of codewords can be restored, M - 15% can be restored, Q - 25% can be restored, H - 30% can be restored.

Boxes

You can draw boxes in your labels:

box = Zebra::Zpl::Box.new :position => [20, 20], :end_position => [100, 100], :line_thickness => 39

Elements Rotation

All printable elements can be rotated on the label, using the :Rotation option. The accepted rotation values are:

• Zebra::Zpl::Rotation::NO_ROTATION: will not rotate the element.
• Zebra::Zpl::Rotation::DEGREES_90: will rotate the element 90 degrees.
• Zebra::Zpl::Rotation::DEGREES_180: will rotate the element 180 degrees.
• Zebra::Zpl::Rotation::DEGREES_270: will rotate the element 270 degrees.

Elements Justification

There are four ZPL-supported :Justification parameters. "LEFT" (left-justified) is the default.

• Zebra::Zpl::Justification::LEFT ~ left-justified
• Zebra::Zpl::Justification::RIGHT ~ right-justified
• Zebra::Zpl::Justification::CENTER ~ centered
• Zebra::Zpl::Justification::JUSTIFIED ~ full-width-justifed (YMMV)

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request