src/third_party/QR-Code-generator/Readme.markdown - cobalt - Git at Google

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


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

 This project aims to be the best, clearest QR Code generator library in multiple languages. The primary goals are flexible options and absolute correctness. Secondary goals are compact implementation size and good documentation comments.

 Home page with live JavaScript demo, extensive descriptions, and competitor comparisons: [https://www.nayuki.io/page/qr-code-generator-library](https://www.nayuki.io/page/qr-code-generator-library)


 Features
 --------

 Core features:

 * Available in 6 programming languages, all with nearly equal functionality: Java, JavaScript, Python, C++, C, Rust
 * Significantly shorter code but more documentation comments compared to competing libraries
 * Supports encoding all 40 versions (sizes) and all 4 error correction levels, as per the QR Code Model 2 standard
 * Output formats: Raw modules/pixels of the QR symbol (all languages), SVG XML string (all languages except C), `BufferedImage` raster bitmap (Java only), HTML5 canvas (JavaScript only)
 * Encodes numeric and special-alphanumeric text in less space than general text
 * 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 (all languages except C)

 Optional advanced features (Java only):

 * 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 parts


 Examples
 --------

 Java language:

     import java.awt.image.BufferedImage;
     import java.io.File;
     import javax.imageio.ImageIO;
     import io.nayuki.qrcodegen.*;

     // Simple operation
     QrCode qr0 = QrCode.encodeText("Hello, world!", QrCode.Ecc.MEDIUM);
     BufferedImage img = qr0.toImage(4, 10);
     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) ...)
         }
     }

 JavaScript language:

     // Name abbreviated for the sake of these examples here
     var QRC = qrcodegen.QrCode;

     // Simple operation
     var qr0 = QRC.encodeText("Hello, world!", QRC.Ecc.MEDIUM);
     var svg = qr0.toSvgString(4);

     // Manual operation
     var segs = qrcodegen.QrSegment.makeSegments("3141592653589793238462643383");
     var qr1 = QRC.encodeSegments(segs, QRC.Ecc.HIGH, 5, 5, 2, false);
     for (var y = 0; y < qr1.size; y++) {
         for (var x = 0; x < qr1.size; x++) {
             (... paint qr1.getModule(x, y) ...)
         }
     }

 Python language:

     from qrcodegen import *

     # Simple operation
     qr0 = QrCode.encode_text("Hello, world!", QrCode.Ecc.MEDIUM)
     svg = qr0.to_svg_str(4)

     # Manual operation
     segs = QrSegment.make_segments("3141592653589793238462643383")
     qr1 = QrCode.encode_segments(segs, QrCode.Ecc.HIGH, 5, 5, 2, False)
     for y in range(qr1.get_size()):
         for x in range(qr1.get_size()):
             (... paint qr1.get_module(x, y) ...)

 C++ language:

     #include <string>
     #include <vector>
     #include "QrCode.hpp"
     using namespace qrcodegen;

     // Simple operation
     QrCode qr0 = QrCode::encodeText("Hello, world!", QrCode::Ecc::MEDIUM);
     std::string svg = qr0.toSvgString(4);

     // Manual operation
     std::vector<QrSegment> segs =
         QrSegment::makeSegments("3141592653589793238462643383");
     QrCode qr1 = QrCode::encodeSegments(
         segs, QrCode::Ecc::HIGH, 5, 5, 2, false);
     for (int y = 0; y < qr1.getSize(); y++) {
         for (int x = 0; x < qr1.getSize(); x++) {
             (... paint qr1.getModule(x, y) ...)
         }
     }

 C language:

     #include <stdbool.h>
     #include <stdint.h>
     #include "qrcodegen.h"

     // Text data
     uint8_t qr0[qrcodegen_BUFFER_LEN_MAX];
     uint8_t tempBuffer[qrcodegen_BUFFER_LEN_MAX];
     bool ok = qrcodegen_encodeText("Hello, world!",
         tempBuffer, qr0, qrcodegen_Ecc_MEDIUM,
         qrcodegen_VERSION_MIN, qrcodegen_VERSION_MAX,
         qrcodegen_Mask_AUTO, true);
     if (!ok)
         return;

     int size = qrcodegen_getSize(qr0);
     for (int y = 0; y < size; y++) {
         for (int x = 0; x < size; x++) {
             (... paint qrcodegen_getModule(qr0, x, y) ...)
         }
     }

     // Binary data
     uint8_t dataAndTemp[qrcodegen_BUFFER_LEN_FOR_VERSION(7)]
         = {0xE3, 0x81, 0x82};
     uint8_t qr1[qrcodegen_BUFFER_LEN_FOR_VERSION(7)];
     ok = qrcodegen_encodeBinary(dataAndTemp, 3, qr1,
         qrcodegen_Ecc_HIGH, 2, 7, qrcodegen_Mask_4, false);

 Rust language:

     extern crate qrcodegen;
     use qrcodegen::QrCode;
     use qrcodegen::QrCodeEcc;
     use qrcodegen::QrSegment;

     // Simple operation
     let qr0 = QrCode::encode_text("Hello, world!",
         QrCodeEcc::Medium).unwrap();
     let svg = qr0.to_svg_string(4);

     // Manual operation
     let chrs: Vec<char> = "3141592653589793238462643383".chars().collect();
     let segs = QrSegment::make_segments(&chrs);
     let qr1 = QrCode::encode_segments_advanced(
         &segs, QrCodeEcc::High, 5, 5, Some(2), false).unwrap();
     for y in 0 .. qr1.size() {
         for x in 0 .. qr1.size() {
             (... paint qr1.get_module(x, y) ...)
         }
     }

 More information about QR Code technology and this library's design can be found on the project home page.


 License
 -------

 Copyright © 2017 Project Nayuki. (MIT License)
 [https://www.nayuki.io/page/qr-code-generator-library](https://www.nayuki.io/page/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.
	QR Code generator library
	=========================


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

	This project aims to be the best, clearest QR Code generator library in multiple languages. The primary goals are flexible options and absolute correctness. Secondary goals are compact implementation size and good documentation comments.

	Home page with live JavaScript demo, extensive descriptions, and competitor comparisons: [https://www.nayuki.io/page/qr-code-generator-library](https://www.nayuki.io/page/qr-code-generator-library)


	Features
	--------

	Core features:

	* Available in 6 programming languages, all with nearly equal functionality: Java, JavaScript, Python, C++, C, Rust
	* Significantly shorter code but more documentation comments compared to competing libraries
	* Supports encoding all 40 versions (sizes) and all 4 error correction levels, as per the QR Code Model 2 standard
	* Output formats: Raw modules/pixels of the QR symbol (all languages), SVG XML string (all languages except C), `BufferedImage` raster bitmap (Java only), HTML5 canvas (JavaScript only)
	* Encodes numeric and special-alphanumeric text in less space than general text
	* 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 (all languages except C)

	Optional advanced features (Java only):

	* 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 parts


	Examples
	--------

	Java language:

	import java.awt.image.BufferedImage;
	import java.io.File;
	import javax.imageio.ImageIO;
	import io.nayuki.qrcodegen.*;

	// Simple operation
	QrCode qr0 = QrCode.encodeText("Hello, world!", QrCode.Ecc.MEDIUM);
	BufferedImage img = qr0.toImage(4, 10);
	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) ...)
	}
	}

	JavaScript language:

	// Name abbreviated for the sake of these examples here
	var QRC = qrcodegen.QrCode;

	// Simple operation
	var qr0 = QRC.encodeText("Hello, world!", QRC.Ecc.MEDIUM);
	var svg = qr0.toSvgString(4);

	// Manual operation
	var segs = qrcodegen.QrSegment.makeSegments("3141592653589793238462643383");
	var qr1 = QRC.encodeSegments(segs, QRC.Ecc.HIGH, 5, 5, 2, false);
	for (var y = 0; y < qr1.size; y++) {
	for (var x = 0; x < qr1.size; x++) {
	(... paint qr1.getModule(x, y) ...)
	}
	}

	Python language:

	from qrcodegen import *

	# Simple operation
	qr0 = QrCode.encode_text("Hello, world!", QrCode.Ecc.MEDIUM)
	svg = qr0.to_svg_str(4)

	# Manual operation
	segs = QrSegment.make_segments("3141592653589793238462643383")
	qr1 = QrCode.encode_segments(segs, QrCode.Ecc.HIGH, 5, 5, 2, False)
	for y in range(qr1.get_size()):
	for x in range(qr1.get_size()):
	(... paint qr1.get_module(x, y) ...)

	C++ language:

	#include <string>
	#include <vector>
	#include "QrCode.hpp"
	using namespace qrcodegen;

	// Simple operation
	QrCode qr0 = QrCode::encodeText("Hello, world!", QrCode::Ecc::MEDIUM);
	std::string svg = qr0.toSvgString(4);

	// Manual operation
	std::vector<QrSegment> segs =
	QrSegment::makeSegments("3141592653589793238462643383");
	QrCode qr1 = QrCode::encodeSegments(
	segs, QrCode::Ecc::HIGH, 5, 5, 2, false);
	for (int y = 0; y < qr1.getSize(); y++) {
	for (int x = 0; x < qr1.getSize(); x++) {
	(... paint qr1.getModule(x, y) ...)
	}
	}

	C language:

	#include <stdbool.h>
	#include <stdint.h>
	#include "qrcodegen.h"

	// Text data
	uint8_t qr0[qrcodegen_BUFFER_LEN_MAX];
	uint8_t tempBuffer[qrcodegen_BUFFER_LEN_MAX];
	bool ok = qrcodegen_encodeText("Hello, world!",
	tempBuffer, qr0, qrcodegen_Ecc_MEDIUM,
	qrcodegen_VERSION_MIN, qrcodegen_VERSION_MAX,
	qrcodegen_Mask_AUTO, true);
	if (!ok)
	return;

	int size = qrcodegen_getSize(qr0);
	for (int y = 0; y < size; y++) {
	for (int x = 0; x < size; x++) {
	(... paint qrcodegen_getModule(qr0, x, y) ...)
	}
	}

	// Binary data
	uint8_t dataAndTemp[qrcodegen_BUFFER_LEN_FOR_VERSION(7)]
	= {0xE3, 0x81, 0x82};
	uint8_t qr1[qrcodegen_BUFFER_LEN_FOR_VERSION(7)];
	ok = qrcodegen_encodeBinary(dataAndTemp, 3, qr1,
	qrcodegen_Ecc_HIGH, 2, 7, qrcodegen_Mask_4, false);

	Rust language:

	extern crate qrcodegen;
	use qrcodegen::QrCode;
	use qrcodegen::QrCodeEcc;
	use qrcodegen::QrSegment;

	// Simple operation
	let qr0 = QrCode::encode_text("Hello, world!",
	QrCodeEcc::Medium).unwrap();
	let svg = qr0.to_svg_string(4);

	// Manual operation
	let chrs: Vec<char> = "3141592653589793238462643383".chars().collect();
	let segs = QrSegment::make_segments(&chrs);
	let qr1 = QrCode::encode_segments_advanced(
	&segs, QrCodeEcc::High, 5, 5, Some(2), false).unwrap();
	for y in 0 .. qr1.size() {
	for x in 0 .. qr1.size() {
	(... paint qr1.get_module(x, y) ...)
	}
	}

	More information about QR Code technology and this library's design can be found on the project home page.


	License
	-------

	Copyright © 2017 Project Nayuki. (MIT License)
	[https://www.nayuki.io/page/qr-code-generator-library](https://www.nayuki.io/page/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.