Add SVG support

[danielpuglisi]

This PR adds SVG support (#22).

To support both SVG and PNG during the HTML layout generation I added image data url support: https://github.com/damoiser/qr-bills/compare/master...codegestalt:svg-support?expand=1#diff-1707220acf1a40ad0f84d3991ef6d6f567c0b9b63b390548a0ef7e1047d17989R11

The parameter qrcode_filepath has been removed. Using base64 encryption we don't need to touch the file system for the png format anymore and can use the existing layout without having to add additional format logic.

The parameter qrcode_format has been added. As when generating HTML with params[:output_params][:format] there was no way of specifying the qr code format. params[:qrcode_format] solves this. Although I think this is a bit smelly. Imo QRBills.generate should just focus on generating the entire HTML payslip and remove support for creating png / svg qr codes and leave that logic to QRGenerator.create. I would even go so far as to remove QRBills.generate entirely and tell people to use QRHTMLayout.create for generating an entire payslip and QRGenerator.create for just qr codes.

[danielpuglisi]

Added some SVG optimizations based on:

• https://codepen.io/tigt/post/optimizing-svgs-in-data-uris
• https://github.com/rails/sprockets/blob/master/lib/sprockets/context.rb#L277-L303
• https://github.com/rails/sprockets/issues/425

[damoiser]

thx for the PR! I would need to do some more deep checks on the svg changes, in the meantime, can you please check my feedback and fix the merge conflicts?

[danielpuglisi]

Merge conflicts are fixed. I don't see any other feedback regarding this PR. Did you add comments somewhere that I might have missed?

Regarding the code changes: There are some potential backwards incompatibilities if existing users call the following methods directly in their code base:

• QRGenerator.create does not accept the entire QRParams hash anymore, just the params[:bill_params] as that's the only data needed to create the QR code.
• QRHTMLLayout.html_layout now requires a new parameter qrcode_data_url.

[damoiser]

sorry forget to publish the feedbacks, you should see now @danielpuglisi

[danielpuglisi]

Latest commit addresses your comments:

• Added version constraint to rqrcode gem
• Optimized swiss_cross.svg and SVG generation
• Updated methods to be backwards compatible
• Added a deprecation warning for the png variant that touches the filesystem

[damoiser]

thx a lot for the great PR @danielpuglisi !

[danielpuglisi]

You're welcome, thx for merging 🙏😊