This implementation is using the bit matrix returned by zxing,
and then we do our own SVG rendering.
The SIX-supplied Swiss Cross SVG version is now used for the overlay.
The resulting SVG has been successfully tested in a number of different SVG
rendering engines:
• Google Chrome 86
• Firefox 82
• Emacs 26
• GIMP
• Inkscape
• Mobile Safari
When rendering the SVG onto 1265x1265 px at 600 dpi,
the resulting image matches the PNG version exactly.
The SIX reference implementation in Java that can be found at
https://www.paymentstandards.ch/dam/downloads/qrcodegenerator.java
uses the zxing library to generate their QR codes.
zxing is also available as a Go version, which we now use.
This means the QR codes can be compared visually to the reference.
