qrcode

qrcode

A simple QR Code generator, using https://github.com/skip2/go-qrcode/

This is LARGELY based on the sample CLI from go-qrcode (above), but takes input from stdin, and infers how the output should look (based on whether this is run from a terminal or not).

Install

$ go get -u github.com/stensonb/qrcode

A command-line tool qrcode will be built into $GOPATH/bin/.

Usage

$ qrcode -h
qrcode -- QR Code encoder in Go
https://github.com/stensonb/qrcode

Flags:
  -d	disable QR Code border
  -i	invert black and white
  -s int
    	image size (pixel) (default 256)
  -t	print as text-art on STDOUT (default true)

Data read from STDIN, and written to STDOUT.  If STDOUT is a terminal device, print as text-art.
If STDOUT is not a terminal (unix pipe, for example), create a PNG image and write to STDOUT.

Usage:
  1. Output a text-art QR code to the terminal:
       echo "hello world" | qrcode

  2. Save a PNG image to file:
       echo "hello world" | qrcode > out.png

  3. Pipe PNG image to 'display' (on any X server):
       echo "hello world" | qrcode | display

  4. Force output to PNG image (just the bytes), when writing to a terminal-based STDOUT:
       echo "hello world" | qrcode -t=false

Maximum capacity

The maximum capacity of a QR Code varies according to the content encoded and the error recovery level. The maximum capacity is 2,953 bytes, 4,296 alphanumeric characters, 7,089 numeric digits, or a combination of these.

Borderless QR Codes

To aid QR Code reading software, QR codes have a built in whitespace border.

If you know what you're doing, and don't want a border, see https://gist.github.com/skip2/7e3d8a82f5317df9be437f8ec8ec0b7d for how to do it. It's still recommended you include a border manually.

Links

• http://en.wikipedia.org/wiki/QR_code
• ISO/IEC 18004:2006 - Main QR Code specification (approx CHF 198,00)
  
• https://github.com/skip2/go-qrcode/ - library used here