Fast QR Code generator library
==============================


Introduction
------------

This Java library generates QR Code symbols, and its design is optimized for speed. It contrasts with another QR library by the same author which is slow but which optimizes for clarity and conciseness. The functionality of this library and its API are nearly identical to the slow library, but it runs anywhere from 1.5× to 10× as fast.

Home page for the fast library (design explanation, benchmarks): [https://www.nayuki.io/page/fast-qr-code-generator-library](https://www.nayuki.io/page/fast-qr-code-generator-library)

Home page for the slow library (live demo, QR Code introduction, competitor comparisons): [https://www.nayuki.io/page/qr-code-generator-library](https://www.nayuki.io/page/qr-code-generator-library)


Features
--------

Core features:

* Supports encoding all 40 versions (sizes) and all 4 error correction levels, as per the QR Code Model 2 standard
* Output format: Raw modules/pixels of the QR symbol
* Encodes numeric and special-alphanumeric text in less space than general text
* Encodes Japanese Unicode text in kanji mode to save a lot of space compared to UTF-8 bytes
* Computes optimal segment mode switching for text with mixed numeric/alphanumeric/general/kanji parts
* Detects finder-like penalty patterns more accurately than other implementations
* Open-source code under the permissive MIT License

Manual parameters:

* User can specify minimum and maximum version numbers allowed, then library will automatically choose smallest version in the range that fits the data
* User can specify mask pattern manually, otherwise library will automatically evaluate all 8 masks and select the optimal one
* User can specify absolute error correction level, or allow the library to boost it if it doesn't increase the version number
* User can create a list of data segments manually and add ECI segments


Examples
--------

    import java.awt.image.BufferedImage;
    import java.io.File;
    import java.util.List;
    import javax.imageio.ImageIO;
    import io.nayuki.fastqrcodegen.*;
    
    // Simple operation
    QrCode qr0 = QrCode.encodeText("Hello, world!", QrCode.Ecc.MEDIUM);
    BufferedImage img = toImage(qr0, 4, 10);  // See QrCodeGeneratorDemo
    ImageIO.write(img, "png", new File("qr-code.png"));
    
    // Manual operation
    List<QrSegment> segs = QrSegment.makeSegments("3141592653589793238462643383");
    QrCode qr1 = QrCode.encodeSegments(segs, QrCode.Ecc.HIGH, 5, 5, 2, false);
    for (int y = 0; y < qr1.size; y++) {
        for (int x = 0; x < qr1.size; x++) {
            (... paint qr1.getModule(x, y) ...)
        }
    }


License
-------

Copyright © 2021 Project Nayuki. (MIT License)  
[https://www.nayuki.io/page/fast-qr-code-generator-library](https://www.nayuki.io/page/fast-qr-code-generator-library)

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

* The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.

* The Software is provided "as is", without warranty of any kind, express or
  implied, including but not limited to the warranties of merchantability,
  fitness for a particular purpose and noninfringement. In no event shall the
  authors or copyright holders be liable for any claim, damages or other
  liability, whether in an action of contract, tort or otherwise, arising from,
  out of or in connection with the Software or the use or other dealings in the
  Software.