B4J Library QR Code Generator (for Server)

Reposting to make this easier to find (original post https://www.b4x.com/android/forum/threads/solved-jserver-html-js.123679/post-772727)

This is a QR code generator for B4J projects. It doesnt require jShell so it will work on B4J server projects.

It is a wrapper for this library https://github.com/nayuki/QR-Code-generator

One of the methods returns base64 encoded png that you can embed in your response HTML (see here if you are not familar with base64 images in HTML - https://www.base64-image.de/tutorial). Most of the libraries/code on the forum only writes an image.

There are three methods in the library;

• EncodeTextToSvgString - returns the QRcode as a SVG string
• EncodeTextToBase64 - returns the QRcode as a base64 image (as a string) you can embed
• EncodeTextToPNG - writes the QRcode as a png file

Example code using base64 encoding;

Dim qr As qrcodegen
qr.Initialize

Dim base64 As String = qr.EncodeTextToBase64(input(0),5)
    
resp.Write($"<img src="data:image/jpeg;base64,${base64}" width="200" height="200" alt="base64 test">"$)

Or to write out to a png file;

Dim qr As qrcodegen
qr.Initialize
qr.EncodeTextToPNG("Hello World",File.DirTemp,"output.png")