homepage/source/qr/html5-qrcode.js

65 lines
2.1 KiB
JavaScript

//---------------------------------------------------------------------
// JavaScript-HTML5 QRCode Generator
//
// Copyright (c) 2011 Amanuel Tewolde
//
// Licensed under the MIT license:
// http://www.opensource.org/licenses/mit-license.php
//
//---------------------------------------------------------------------
// Generates a QRCode of text provided.
// First QRCode is rendered to a canvas.
// The canvas is then turned to an image PNG
// before being returned as an <img> tag.
function showQRCode(text) {
var dotsize = 5; // size of box drawn on canvas
var padding = 10; // (white area around your QRCode)
var black = "rgb(0,0,0)";
var white = "rgb(255,255,255)";
var QRCodeVersion = 15; // 1-40 see http://www.denso-wave.com/qrcode/qrgene2-e.html
var canvas=document.createElement('canvas');
var qrCanvasContext = canvas.getContext('2d');
try {
// QR Code Error Correction Capability
// Higher levels improves error correction capability while decreasing the amount of data QR Code size.
// QRErrorCorrectLevel.L (5%) QRErrorCorrectLevel.M (15%) QRErrorCorrectLevel.Q (25%) QRErrorCorrectLevel.H (30%)
// eg. L can survive approx 5% damage...etc.
var qr = new QRCode(QRCodeVersion, QRErrorCorrectLevel.L);
qr.addData(text);
qr.make();
}
catch(err) {
var errorChild = document.createElement("p");
var errorMSG = document.createTextNode("QR Code FAIL! " + err);
errorChild.appendChild(errorMSG);
return errorChild;
}
var qrsize = qr.getModuleCount();
canvas.setAttribute('height',(qrsize * dotsize) + padding);
canvas.setAttribute('width',(qrsize * dotsize) + padding);
var shiftForPadding = padding/2;
if (canvas.getContext){
for (var r = 0; r < qrsize; r++) {
for (var c = 0; c < qrsize; c++) {
if (qr.isDark(r, c))
qrCanvasContext.fillStyle = black;
else
qrCanvasContext.fillStyle = white;
qrCanvasContext.fillRect ((c*dotsize) +shiftForPadding,(r*dotsize) + shiftForPadding,dotsize,dotsize); // x, y, w, h
}
}
}
var imgElement = document.createElement("img");
imgElement.src = canvas.toDataURL("image/png");
return imgElement;
}