How to Draw Chinese on QR Code with Ruby

2 min readNov 29, 2017

Prepare

Tools

Here’s a to-install list, add in your Gemfile:

rQRCode + rqrcode_png— generate QR code

gem 'rqrcode_png'

2. RMagick — Draw text on image

gem 'rmagick'

3. ImageMagick — Core engine of RMagick

4. And You need a Font type to draw Chinese. I prefer LiHei Pro

P.S. Why you need a Font type to implement Chinese drawing?
At my first try, every Chinese change to ?. You think it’s a encoding issue? Nope, It’s about Drawing issue. The default font type can’t draw UTF-8 into Chinese. So we need a new Font Type.
You can know about how to add a Font Type in Ubuntu here.

Steps

Generate QR code from url

qr_code_img = RQRCode::QRCode.new("https://www.google.com").as_png(
     resize_gte_to: false,
     resize_exactly_to: false,
     fill: 'white',
     color: 'black',
     size: 480,
     border_modules: 4,
     module_px_size: 6,
     file: "google_qrcode.png" # path to write
)

You can also save image as SVG, HTML or ANSI string by simply call method.

require 'rqrcode'

qrcode = RQRCode::QRCode.new("http://github.com/")
image = qrcode.as_png
svg = qrcode.as_svg
html = qrcode.as_html
string = qrcode.as_ansi
string = qrcode.to_s

Then we have the QR code

2. Draw down your text

img = ImageList.new("google_qrcode.png")
txt = Draw.new
txt.font = '/usr/share/fonts/truetype/lihei-pro.ttf'
   
img.annotate(txt, 0,0,0,10, c.name.force_encoding("UTF-8")){
   txt.gravity = Magick::SouthGravity
   txt.pointsize = 25
   txt.fill = '#000000'
   }file = File.new("google_final.png", File::CREAT|File::TRUNC|File::RDWR, 0644)img.write(file)

Parameters of .annotate is ( Draw draw, width, height, x, y, “text to add”)

And you can change the gravity on image and the Font style.

In my case, the output image: