Qr

Encoder only headless qr code generator for Kotlin/Java/JVM.

It's a port of https://github.com/Rich-Harris/headless-qr which is adapted from https://github.com/kazuhikoarase/qrcode-generator itself under the following license (MIT),

   QR Code Generator for JavaScript

   Copyright (c) 2009 Kazuhiko Arase

   URL: http://www.d-project.com/

   Licensed under the MIT license:
    http://www.opensource.org/licenses/mit-license.php

   The word 'QR Code' is registered trademark of
   DENSO WAVE INCORPORATED
    http://www.denso-wave.com/qrcode/faqpatent-e.html

It's actually not ported directly from the JavaScript version but from the Dart version https://github.com/ebraminio/headless_qr as the intermediary step.

Most of it's source history exists here

Usage

Add this in your root build.gradle at the end of repositories section:

allprojects {
    repositories {
        ...
        maven("https://jitpack.io")
    }
}

Now actually add the dependency:

dependencies {
    implementation("com.github.persian-calendar:qr:LATEST_GIT_HASH")
}

For other build tools support have a look at this.

Tests

jvmTest decodes what this library encodes with ZXing, and the text has to come back exactly as it went in. ZXing shares no code with this library, and reading the message back exercises the whole of the standard at once: the mode and the character count, the padding, the Reed-Solomon blocks and their error correction, the mask, the format and the version information, and the placement of all of it. A few of the tests go through a drawn image as well, so that a scanner's view of the code - the finder, timing and alignment patterns - is covered too.

There is also a fuzzer, which throws random payloads at the encoder and decodes every one of them back. It is seeded, so a failure can be replayed, and both the seed and the number of cases can be moved from the command line:

./gradlew jvmTest
./gradlew jvmTest -Dqr.fuzz.seed=12345 -Dqr.fuzz.cases=5000

CI runs it twice over: once inside jvmTest with the default 400 cases, and again in a job of its own with 5000 cases and a seed taken from the run number, so every run explores payloads no earlier run did. The test prints the seed it used, and the workflow can be started by hand with fuzz-seed set to that number to replay the same cases.

Web demo

There is a small demo of this library in the web module, which encodes to JavaScript and to WebAssembly and draws the code in the browser.