Generate QR Codes Using Libqrencode

On 5 minutes, 29 seconds read By Edward
A picture of a QR scanner to signify how to generate QR code uses

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Creating And Reading Barcodes

A barcode is a method of representing machine-readable images consisting of black and white bars.

Multiple tools are available for generating barcodes. Some are command-line only, while others have a GUI.

In a 1D barcode, data is scanned in a linear sequence using a series of vertical lines and spaces of varying widths to encode data.

There are many different types of 2D barcodes such as QR code and Aztec code. QR codes are matrix barcodes that can contain alphanumeric and binary data. A popular use of QR codes is to share a link to a website for people with mobile devices.

In this tutorial, the Libqrencode library will be used to encode data in a QR code. The test will consist of encoding simple text, then URLs and finally an address book entry in vCard format.

Requirements For Barcode Generator

Glossary:

GUI

Graphical User Interface allows users to interact with electronic devices through graphic icons and indicators.

1D

One-dimensional or linear.

2D

Two-dimensional developed, using geometric patterns like rectangles, dots, and hexagons.

Data Matrix

Two-dimensional barcode with uniquely generated patterns of square modules.

vCard

Virtual Contact File (VCF) is a file format standard for electronic business cards.

Common Barcodes

Popular Barcodes
Name Description Example
1D Barcode Scanned horizontally and can hold 85 characters. Universal Product Code (UPC).
2D Barcode Scanned horizontally and vertically and can hold 7089 characters. QR Code.
Name Description Example

Generate QR Codes Via Libqrencode

# Create Text Link In QR Code #
qrencode -o qrcode1.png 'https://ojambo.com'
# Create Text Link With Increased Border Width Pixels In QR Code #
qrencode -m 10 -o qrcode2.png 'https://ojambo.com'
# Create Text Link With Increased Border Width And Height Pixels In QR Code #
qrencode -s 4 -m 10 -o qrcode3.png 'https://ojambo.com'
# Create Text Address Book Entry In QR Code #
cat > vcard.vcf << 'EOF'
BEGIN:VCARD
VERSION:3.0
FN:Edward Ojambo
N:Ojambo;Edward;;;
EMAIL;type=HOME,INTERNET:edward@ojamboshow.local
URL:https://ojambo.com
END:VCARD
EOF
cat vcard.vcf | qrencode -o address.png

Download

The Libqrencode library can be downloaded from Libqrencode Library and installed on your workstation.

Explanation

  1. Generate a file with your QR code.
  2. Test the QR Code on your scanning device such as a smartphone.
  3. Optionally tweak the width and height of the border in pixels.
  4. In order to generate a VCF-encoded QR code, place the contents in a separate file (literal VCF).
  5. The library accepts a string or a list of data chunks.

Libqrencode Generated Link QR Code
Libqrencode Generated Link QR Code As PNG Image Scanned

Libqrencode Generated Tweaked Link QR Code
Libqrencode Generated Tweaked Link QR Code As PNG Image Scanned

Libqrencode Generated vCard QR Code
Libqrencode Generated vCard Code As PNG Image Scanned


Usage

You can use the Libqrencode command line tool to generate QR codes using the default settings. For this tutorial, QR codes were generated for plain text, URL and vCard. You can use generated QR codes for even ticketing and product information among other uses.

Open Source

Libqrencode is licensed under the terms of the GNU Lesser General Public License (LGPL) version 2.1. The copyleft license comes with strict rules and requirements to ensure the software remains free and open-source. It allows commercial use, modification, distribution, and allows making derivatives proprietary, consult the license for more specific details.

Conclusion:

Libqrencode can be used to generate QR codes on your local computer without restrictions. You can generated encoded text, URL, VCF and more on the command line. You are able to tweak the height and border pixels.

If you enjoy this article, consider supporting me by purchasing one of my OjamboShop.com Online Programming Courses or publications at Edward Ojambo Programming Books or simply donate here Ojambo.com Donate

References:

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