Class: Payday::QrCode

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

Overview

Draws a QR code as an SVG.

The matrix comes straight from RQRCode, so the payload and its error correction level are untouched and the code carries exactly the same data it always did. Only the drawing changes: vector instead of a 200px raster, lightly rounded modules, and the three finder patterns drawn as rounded frames.

Rounding is kept deliberately slight. These codes are scanned off paper, sometimes off a bad photocopy, and on a Verifactu invoice a code that will not scan is a compliance problem rather than a cosmetic one. Modules keep their full square footprint apart from a softened corner, so a scanner sees the same geometry the old raster produced.

Constant Summary collapse

QUIET_ZONE =

modules of clear space; the QR spec's minimum

4
UNIT =

user units per module

10
RADIUS =

corner radius of a data module, out of UNIT

1.5
FINDER =

finder patterns are 7 modules square

7
EYE_RADIUS =

Corner radius of a finder frame. Above roughly 1.2 modules the curve starts cutting the corner module out of the ring, which changes what a scanner reads.

10
DARK = 
'#111111'
LIGHT = 
'#ffffff'

Instance Method Summary collapse

Constructor Details

#initialize(data) ⇒ QrCode

Returns a new instance of QrCode.



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# File 'lib/payday/qr_code.rb', line 30

def initialize(data)
  @modules = RQRCode::QRCode.new(data.to_s).modules
end

Instance Method Details

#to_svg ⇒ Object 



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# File 'lib/payday/qr_code.rb', line 34

def to_svg
  <<~SVG
    <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 #{side} #{side}" shape-rendering="geometricPrecision">
    <rect width="#{side}" height="#{side}" fill="#{LIGHT}"/>
    #{(data_modules + finders).join("\n")}
    </svg>
  SVG
end