QR-Code-generator/javascript/qrcodegen-demo.js

/* 
 * QR Code generator demo (JavaScript)
 * 
 * Copyright (c) 2016 Project Nayuki
 * https://www.nayuki.io/page/qr-code-generator-library
 * 
 * (MIT License)
 * 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.
 */

"use strict";


function redrawQrCode() {
	// Get error correction level
	var ecl;
	if (document.getElementById("errcorlvl-medium").checked)
		ecl = qrcodegen.QrCode.Ecc.MEDIUM;
	else if (document.getElementById("errcorlvl-quartile").checked)
		ecl = qrcodegen.QrCode.Ecc.QUARTILE;
	else if (document.getElementById("errcorlvl-high").checked)
		ecl = qrcodegen.QrCode.Ecc.HIGH;
	else  // In case no radio button is depressed
		ecl = qrcodegen.QrCode.Ecc.LOW;
	
	// Get text and compute QR Code
	var text = document.getElementById("text-input").value;
	var qr = qrcodegen.encodeText(text, ecl);
	
	// Get scale and border
	var scale = parseInt(document.getElementById("scale-input").value, 10);
	var border = parseInt(document.getElementById("border-input").value, 10);
	if (scale <= 0 || border < 0 || scale > 30 || border > 100)
		return;
	
	// Draw QR Code onto canvas
	var canvas = document.getElementById("qrcode-canvas");
	var width = (qr.getSize() + border * 2) * scale;
	if (canvas.width != width) {
		canvas.width = width;
		canvas.height = width;
	}
	var ctx = canvas.getContext("2d");
	for (var y = -border; y < qr.getSize() + border; y++) {
		for (var x = -border; x < qr.getSize() + border; x++) {
			ctx.fillStyle = qr.getModule(x, y) == 1 ? "#000000" : "#FFFFFF";
			ctx.fillRect((x + border) * scale, (y + border) * scale, scale, scale);
		}
	}
	
	// Show statistics
	var stats = "QR Code version = " + qr.getVersion() + ", ";
	stats += "mask pattern = " + qr.getMask() + ", ";
	stats += "character count = " + countUnicodeChars(text) + ",\n";
	stats += "encoding mode = ";
	var seg = qrcodegen.encodeTextToSegment(text);
	if (seg.getMode() == qrcodegen.QrSegment.Mode.NUMERIC)
		stats += "numeric";
	else if (seg.getMode() == qrcodegen.QrSegment.Mode.ALPHANUMERIC)
		stats += "alphanumeric";
	else if (seg.getMode() == qrcodegen.QrSegment.Mode.BYTE)
		stats += "byte";
	else if (seg.getMode() == qrcodegen.QrSegment.Mode.BYTE)
		stats += "kanji";
	else
		stats += "unknown";
	stats += ", data bits = " + (4 + seg.getMode().numCharCountBits(qr.getVersion()) + seg.getBits().length) + ".";
	var elem = document.getElementById("statistics-output");
	while (elem.firstChild != null)
		elem.removeChild(elem.firstChild);
	elem.appendChild(document.createTextNode(stats));
}


function countUnicodeChars(str) {
	var result = 0;
	for (var i = 0; i < str.length; i++, result++) {
		var c = str.charCodeAt(i);
		if (c < 0xD800 || c >= 0xE000)
			continue;
		else if (0xD800 <= c && c < 0xDC00) {  // High surrogate
			i++;
			var d = str.charCodeAt(i);
			if (0xDC00 <= d && d < 0xE000)  // Low surrogate
				continue;
		}
		throw "Invalid UTF-16 string";
	}
	return result;
}


redrawQrCode();