Class: PutQR::QRCode

Inherits:
Object
  • Object
show all
Defined in:
lib/putqr.rb

Overview

Display a QR code in your terminal.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(content) ⇒ QRCode

Initialize the QR code with a string.



14
15
16
 
# File 'lib/putqr.rb', line 14

def initialize(content)
  @qrcode = QRCode.generate_qrcode(content)
end

Instance Attribute Details

#qrcode ⇒ Object (readonly)

Returns the value of attribute qrcode.



11
12
13
 
# File 'lib/putqr.rb', line 11

def qrcode
  @qrcode
end

Class Method Details

.generate_qrcode(content) ⇒ Object 



65
66
67
68
69
70
71
72
73
74
75
 
# File 'lib/putqr.rb', line 65

def self.generate_qrcode(content)
  # Try each size until one fits
  (min_qr_version(content.size)..40).each do |version|
    begin
      return RQRCode::QRCode.new(content, level: :h, size: version)
    rescue RQRCode::QRCodeRunTimeError
      next
    end
  end
  nil
end

.min_qr_version(input_size) ⇒ Object 



77
78
79
80
81
82
83
84
85
86
87
 
# File 'lib/putqr.rb', line 77

def self.min_qr_version(input_size)
  # Skip the lower QR code versions where the input is known to be too
  # long. These figures are based on the maximum number of characters
  # that can be encoded for a numeric string with high error correction.
  if    input_size >= 2_524 then 36
  elsif input_size >= 1_897 then 31
  elsif input_size >=   969 then 21
  elsif input_size >=   331 then 11
  else 1
  end
end

Instance Method Details

#render ⇒ Object

Render the QR code using the best method available for the terminal. Returns a string.



25
26
27
28
29
30
31
 
# File 'lib/putqr.rb', line 25

def render
  if ENV['TERM_PROGRAM'].start_with? 'iTerm'
    render_image_iterm2
  else
    render_ansi
  end
end

#render_ansi ⇒ Object

Render the QR code using ANSI escape codes. Returns a string.



35
36
37
 
# File 'lib/putqr.rb', line 35

def render_ansi
  qrcode.as_ansi if valid?
end

#render_image ⇒ Object

Render the QR code as an inline image. Returns a string.



41
42
43
 
# File 'lib/putqr.rb', line 41

def render_image
  render_image_iterm2
end

#render_image_iterm2 ⇒ Object

Render the QR code as an inline image for iTerm2. Returns a string.



47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
 
# File 'lib/putqr.rb', line 47

def render_image_iterm2
  return nil unless valid?

  # References:
  # https://iterm2.com/documentation-images.html
  # https://iterm2.com/utilities/imgcat

  # tmux requires some extra work for unrecognised escape code sequences
  screen = ENV['TERM'].start_with? 'screen'
  prefix = screen ? "\ePtmux;\e\e]" : "\e]"
  suffix = screen ? "\a\e\\" : "\a"

  png = qrcode.as_png(size: 600)
  png_base64 = Base64.encode64(png.to_s).chomp
  options = 'inline=1'
  "#{prefix}1337;File=#{options}:#{png_base64}#{suffix}"
end

#valid? ⇒ Boolean

Can the string be encoded as a QR code?

Returns:

  • (Boolean) 


19
20
21
 
# File 'lib/putqr.rb', line 19

def valid?
  !qrcode.nil?
end