需求描述：商家用扫描枪扫用户条形码或二维码实现支付。
效果图：
说明：微信小程序、支付宝小程序的条形码和二维码都可以由一串数字通过 barcode.js 和 qrcode.js 插件绘制在页面的 Canvas 元素上。
两个插件的内容我贴在文章末尾
下面我总结一下基于微信小程序的整个实现流程：
（支付宝小程序类似，只要在微信小程序的基础上稍微改一下就行了）
1. 从后台获取要转换成条形码和二维码的一串数字 code
2. 分别用 barcode.js 和 qrcode.js 把数字绘制成页面canvas里的条形码和二维码
wxml:
view canvas canvas-id="barcode" / view{{codeStr}}/view canvas canvas-id="qrcode" //viewutils.js
import qrcode from './qrcode';import barcode from './barcode';// 插件内部是根据width, height参数的rpx值来进行绘画// 把数字转换成条形码function toBarcode (canvasId, code, width, height) { barcode.code128(wx.createCanvasContext(canvasId), code, width, height);}// 把数字转换成二维码function toQrcode (canvasId, code, width, height) { qrcode.api.draw(code, { ctx: wx.createCanvasContext(canvasId), width, height })}export { toBarcode, toQrcode}// 使用 api
const code = '1221334122546765342';toBarcode('barcode', code, 680, 200);toQrcode('qrcode', code, 420, 420);const codeStr = `${code.slice(0, 4)}****${code.slice(20)}`;3. 轮询请求后台，查看是否已被扫码（其实就是判断后台返回的 code 状态）
getStatus(code); function getStatus (code) { wx.request({ url: '/api/xxx', method: 'GET', data: {code}, success: (res) = { if (res.isSuccess) { // 支付成功后的操作 } else { // 还未支付并且允许轮训的话就继续轮训 if (this.state.caninterval) { setTimeout(() = { getStatus(code); }, 1500) } } } }) }完整代码：
import { toBarcode, toQrcode } from '../utils';Page({ data: { canInterval: true, //判断能不能轮询，作用是控制小程序切换到后台时不进行轮训 code: '', // 转换成条形码、二维码的数字 codeStr: '' }, onLoad () { wx.request({ url: '/api/xxx', method: 'GET', success: (res) = { const { code } = res.data; toBarcode('barcode', code , 680, 200); toQrcode('qrcode', code, 420, 420); const codeStr = `${code.slice(0, 4)}****${code.slice(20)}`; this.setData({ code, codeStr }) this.getStatus(code); } }) }, onShow () { const {code} = this.data; this.setData({ canInterval: true }); code && this.getStatus(code); }, getStatus (code) { wx.request({ url: '', method: 'GET', data: {code}, success: (res) = { if (res.isSuccess) { // 支付成功后的操作 } else { // 还未支付并且允许轮训的话就继续轮训 if (this.state.canInterval) { setTimeout(() = { this.getStatus(code); }, 1000) } } } }) }, onHide () { this.setData({ canInterval: false }) }, onUnload () { this.setData({ canInterval: false }) }})附赠两个插件
barcode.js
/** // https://github.com/alsey/wxbarcode// 最后一位显示 _ 问题// https://github.com/alsey/wxbarcode/issues/2// //ok some type of shift is nessecary if (shifter != -1) { result.push(shifter); result.push(codeValue(chr1));//把这里的chr2改成chr1即可。 }**/!(function(){var CHAR_TILDE = 126;var CODE_FNC1 = 102;var SET_STARTA = 103;var SET_STARTB = 104;var SET_STARTC = 105;var SET_SHIFT = 98;var SET_CODEA = 101;var SET_CODEB = 100;var SET_STOP = 106;var REPLACE_CODES = { CHAR_TILDE: CODE_FNC1 //~ corresponds to FNC1 in GS1-128 standard}var CODESET = { ANY: 1, AB: 2, A: 3, B: 4, C: 5};function getBytes(str) { var bytes = []; for (var i = 0; i str.length; i++) { bytes.push(str.charCodeAt(i)); } return bytes;}exports.code128 = function (ctx, text, width, height) { width = parseInt(width); height = parseInt(height); var codes = stringToCode128(text); var g = new Graphics(ctx, width, height); var barWeight = g.area.width / ((codes.length - 3) * 11 + 35); var x = g.area.left; var y = g.area.top; for (var i = 0; i codes.length; i++) { var c = codes[i]; //two bars at a time: 1 black and 1 white for (var bar = 0; bar 8; bar += 2) { var barW = PATTERNS[c][bar] * barWeight; // var barH = height - y - this.border; var barH = height - y; var spcW = PATTERNS[c][bar + 1] * barWeight; //no need to draw if 0 width if (barW 0) { g.fillFgRect(x, y, barW, barH); } x += barW + spcW; } } ctx.draw();}function stringToCode128(text) { var barc = { currcs: CODESET.C }; var bytes = getBytes(text); //decide starting codeset var index = bytes[0] == CHAR_TILDE ? 1 : 0; var csa1 = bytes.length 0 ? codeSetAllowedFor(bytes[index++]) : CODESET.AB; var csa2 = bytes.length 0 ? codeSetAllowedFor(bytes[index++]) : CODESET.AB; barc.currcs = getBestStartSet(csa1, csa2); barc.currcs = perhapsCodeC(bytes, barc.currcs); //if no codeset changes this will end up with bytes.length+3 //start, checksum and stop var codes = new Array(); switch (barc.currcs) { case CODESET.A: codes.push(SET_STARTA); break; case CODESET.B: codes.push(SET_STARTB); break; default: codes.push(SET_STARTC); break; } for (var i = 0; i bytes.length; i++) { var b1 = bytes[i]; //get the first of a pair //should we translate/replace if (b1 in REPLACE_CODES) { codes.push(REPLACE_CODES[b1]); i++ //jump to next b1 = bytes[i]; } //get the next in the pair if possible var b2 = bytes.length (i + 1) ? bytes[i + 1] : -1; codes = codes.concat(codesForChar(b1, b2, barc.currcs)); //code C takes 2 chars each time if (barc.currcs == CODESET.C) i++; } //calculate checksum according to Code 128 standards var checksum = codes[0]; for (var weight = 1; weight codes.length; weight++) { checksum += (weight * codes[weight]); } codes.push(checksum % 103); codes.push(SET_STOP); //encoding should now be complete return codes; function getBestStartSet(csa1, csa2) { //tries to figure out the best codeset //to start with to get the most compact code var vote = 0; vote += csa1 == CODESET.A ? 1 : 0; vote += csa1 == CODESET.B ? -1 : 0; vote += csa2 == CODESET.A ? 1 : 0; vote += csa2 == CODESET.B ? -1 : 0; //tie goes to B due to my own predudices return vote 0 ? CODESET.A : CODESET.B; } function perhapsCodeC(bytes, codeset) { for (var i = 0; i bytes.length; i++) { var b = bytes[i] if ((b 48 || b 57) && b != CHAR_TILDE) return codeset; } return CODESET.C; } //chr1 is current byte //chr2 is the next byte to process. looks ahead. function codesForChar(chr1, chr2, currcs) { var result = []; var shifter = -1; if (charCompatible(chr1, currcs)) { if (currcs == CODESET.C) { if (chr2 == -1) { shifter = SET_CODEB; currcs = CODESET.B; } else if ((chr2 != -1) && !charCompatible(chr2, currcs)) { //need to check ahead as well if (charCompatible(chr2, CODESET.A)) { shifter = SET_CODEA; currcs = CODESET.A; } else { shifter = SET_CODEB; currcs = CODESET.B; } } } } else { //if there is a next char AND that next char is also not compatible if ((chr2 != -1) && !charCompatible(chr2, currcs)) { //need to switch code sets switch (currcs) { case CODESET.A: shifter = SET_CODEB; currcs = CODESET.B; break; case CODESET.B: shifter = SET_CODEA; currcs = CODESET.A; break; } } else { //no need to shift code sets, a temporary SHIFT will suffice shifter = SET_SHIFT; } } //ok some type of shift is nessecary if (shifter != -1) { result.push(shifter); result.push(codeValue(chr1)); } else { if (currcs == CODESET.C) { //include next as well result.push(codeValue(chr1, chr2)); } else { result.push(codeValue(chr1)); } } barc.currcs = currcs; return result; }}//reduce the ascii code to fit into the Code128 char tablefunction codeValue(chr1, chr2) { if (typeof chr2 == "undefined") { return chr1 = 32 ? chr1 - 32 : chr1 + 64; } else { return parseInt(String.fromCharCode(chr1) + String.fromCharCode(chr2)); }}function charCompatible(chr, codeset) { var csa = codeSetAllowedFor(chr); if (csa == CODESET.ANY) return true; //if we need to change from current if (csa == CODESET.AB) return true; if (csa == CODESET.A && codeset == CODESET.A) return true; if (csa == CODESET.B && codeset == CODESET.B) return true; return false;}function codeSetAllowedFor(chr) { if (chr = 48 && chr = 57) { //0-9 return CODESET.ANY; } else if (chr = 32 && chr = 95) { //0-9 A-Z return CODESET.AB; } else { //if non printable return chr 32 ? CODESET.A : CODESET.B; }}var Graphics = function(ctx, width, height) { this.width = width; this.height = height; this.quiet = Math.round(this.width / 40); this.border_size = 0; this.padding_width = 0; this.area = { width : width - this.padding_width * 2 - this.quiet * 2, height: height - this.border_size * 2, top : this.border_size - 4, left : this.padding_width + this.quiet }; this.ctx = ctx; this.fg = "#000000"; this.bg = "#ffffff"; // fill background this.fillBgRect(0,0, width, height); // fill center to create border this.fillBgRect(0, this.border_size, width, height - this.border_size * 2);}//use native colorGraphics.prototype._fillRect = function(x, y, width, height, color) { this.ctx.setFillStyle(color) this.ctx.fillRect(x, y, width, height)}Graphics.prototype.fillFgRect = function(x,y, width, height) { this._fillRect(x, y, width, height, this.fg);}Graphics.prototype.fillBgRect = function(x,y, width, height) { this._fillRect(x, y, width, height, this.bg);}var PATTERNS = [ [2, 1, 2, 2, 2, 2, 0, 0], // 0 [2, 2, 2, 1, 2, 2, 0, 0], // 1 [2, 2, 2, 2, 2, 1, 0, 0], // 2 [1, 2, 1, 2, 2, 3, 0, 0], // 3 [1, 2, 1, 3, 2, 2, 0, 0], // 4 [1, 3, 1, 2, 2, 2, 0, 0], // 5 [1, 2, 2, 2, 1, 3, 0, 0], // 6 [1, 2, 2, 3, 1, 2, 0, 0], // 7 [1, 3, 2, 2, 1, 2, 0, 0], // 8 [2, 2, 1, 2, 1, 3, 0, 0], // 9 [2, 2, 1, 3, 1, 2, 0, 0], // 10 [2, 3, 1, 2, 1, 2, 0, 0], // 11 [1, 1, 2, 2, 3, 2, 0, 0], // 12 [1, 2, 2, 1, 3, 2, 0, 0], // 13 [1, 2, 2, 2, 3, 1, 0, 0], // 14 [1, 1, 3, 2, 2, 2, 0, 0], // 15 [1, 2, 3, 1, 2, 2, 0, 0], // 16 [1, 2, 3, 2, 2, 1, 0, 0], // 17 [2, 2, 3, 2, 1, 1, 0, 0], // 18 [2, 2, 1, 1, 3, 2, 0, 0], // 19 [2, 2, 1, 2, 3, 1, 0, 0], // 20 [2, 1, 3, 2, 1, 2, 0, 0], // 21 [2, 2, 3, 1, 1, 2, 0, 0], // 22 [3, 1, 2, 1, 3, 1, 0, 0], // 23 [3, 1, 1, 2, 2, 2, 0, 0], // 24 [3, 2, 1, 1, 2, 2, 0, 0], // 25 [3, 2, 1, 2, 2, 1, 0, 0], // 26 [3, 1, 2, 2, 1, 2, 0, 0], // 27 [3, 2, 2, 1, 1, 2, 0, 0], // 28 [3, 2, 2, 2, 1, 1, 0, 0], // 29 [2, 1, 2, 1, 2, 3, 0, 0], // 30 [2, 1, 2, 3, 2, 1, 0, 0], // 31 [2, 3, 2, 1, 2, 1, 0, 0], // 32 [1, 1, 1, 3, 2, 3, 0, 0], // 33 [1, 3, 1, 1, 2, 3, 0, 0], // 34 [1, 3, 1, 3, 2, 1, 0, 0], // 35 [1, 1, 2, 3, 1, 3, 0, 0], // 36 [1, 3, 2, 1, 1, 3, 0, 0], // 37 [1, 3, 2, 3, 1, 1, 0, 0], // 38 [2, 1, 1, 3, 1, 3, 0, 0], // 39 [2, 3, 1, 1, 1, 3, 0, 0], // 40 [2, 3, 1, 3, 1, 1, 0, 0], // 41 [1, 1, 2, 1, 3, 3, 0, 0], // 42 [1, 1, 2, 3, 3, 1, 0, 0], // 43 [1, 3, 2, 1, 3, 1, 0, 0], // 44 [1, 1, 3, 1, 2, 3, 0, 0], // 45 [1, 1, 3, 3, 2, 1, 0, 0], // 46 [1, 3, 3, 1, 2, 1, 0, 0], // 47 [3, 1, 3, 1, 2, 1, 0, 0], // 48 [2, 1, 1, 3, 3, 1, 0, 0], // 49 [2, 3, 1, 1, 3, 1, 0, 0], // 50 [2, 1, 3, 1, 1, 3, 0, 0], // 51 [2, 1, 3, 3, 1, 1, 0, 0], // 52 [2, 1, 3, 1, 3, 1, 0, 0], // 53 [3, 1, 1, 1, 2, 3, 0, 0], // 54 [3, 1, 1, 3, 2, 1, 0, 0], // 55 [3, 3, 1, 1, 2, 1, 0, 0], // 56 [3, 1, 2, 1, 1, 3, 0, 0], // 57 [3, 1, 2, 3, 1, 1, 0, 0], // 58 [3, 3, 2, 1, 1, 1, 0, 0], // 59 [3, 1, 4, 1, 1, 1, 0, 0], // 60 [2, 2, 1, 4, 1, 1, 0, 0], // 61 [4, 3, 1, 1, 1, 1, 0, 0], // 62 [1, 1, 1, 2, 2, 4, 0, 0], // 63 [1, 1, 1, 4, 2, 2, 0, 0], // 64 [1, 2, 1, 1, 2, 4, 0, 0], // 65 [1, 2, 1, 4, 2, 1, 0, 0], // 66 [1, 4, 1, 1, 2, 2, 0, 0], // 67 [1, 4, 1, 2, 2, 1, 0, 0], // 68 [1, 1, 2, 2, 1, 4, 0, 0], // 69 [1, 1, 2, 4, 1, 2, 0, 0], // 70 [1, 2, 2, 1, 1, 4, 0, 0], // 71 [1, 2, 2, 4, 1, 1, 0, 0], // 72 [1, 4, 2, 1, 1, 2, 0, 0], // 73 [1, 4, 2, 2, 1, 1, 0, 0], // 74 [2, 4, 1, 2, 1, 1, 0, 0], // 75 [2, 2, 1, 1, 1, 4, 0, 0], // 76 [4, 1, 3, 1, 1, 1, 0, 0], // 77 [2, 4, 1, 1, 1, 2, 0, 0], // 78 [1, 3, 4, 1, 1, 1, 0, 0], // 79 [1, 1, 1, 2, 4, 2, 0, 0], // 80 [1, 2, 1, 1, 4, 2, 0, 0], // 81 [1, 2, 1, 2, 4, 1, 0, 0], // 82 [1, 1, 4, 2, 1, 2, 0, 0], // 83 [1, 2, 4, 1, 1, 2, 0, 0], // 84 [1, 2, 4, 2, 1, 1, 0, 0], // 85 [4, 1, 1, 2, 1, 2, 0, 0], // 86 [4, 2, 1, 1, 1, 2, 0, 0], // 87 [4, 2, 1, 2, 1, 1, 0, 0], // 88 [2, 1, 2, 1, 4, 1, 0, 0], // 89 [2, 1, 4, 1, 2, 1, 0, 0], // 90 [4, 1, 2, 1, 2, 1, 0, 0], // 91 [1, 1, 1, 1, 4, 3, 0, 0], // 92 [1, 1, 1, 3, 4, 1, 0, 0], // 93 [1, 3, 1, 1, 4, 1, 0, 0], // 94 [1, 1, 4, 1, 1, 3, 0, 0], // 95 [1, 1, 4, 3, 1, 1, 0, 0], // 96 [4, 1, 1, 1, 1, 3, 0, 0], // 97 [4, 1, 1, 3, 1, 1, 0, 0], // 98 [1, 1, 3, 1, 4, 1, 0, 0], // 99 [1, 1, 4, 1, 3, 1, 0, 0], // 100 [3, 1, 1, 1, 4, 1, 0, 0], // 101 [4, 1, 1, 1, 3, 1, 0, 0], // 102 [2, 1, 1, 4, 1, 2, 0, 0], // 103 [2, 1, 1, 2, 1, 4, 0, 0], // 104 [2, 1, 1, 2, 3, 2, 0, 0], // 105 [2, 3, 3, 1, 1, 1, 2, 0] // 106]})();qrcode.js
var QR = (function () { // alignment pattern var adelta = [ 0, 11, 15, 19, 23, 27, 31, // force 1 pat 16, 18, 20, 22, 24, 26, 28, 20, 22, 24, 24, 26, 28, 28, 22, 24, 24, 26, 26, 28, 28, 24, 24, 26, 26, 26, 28, 28, 24, 26, 26, 26, 28, 28 ]; // version block var vpat = [ 0xc94, 0x5bc, 0xa99, 0x4d3, 0xbf6, 0x762, 0x847, 0x60d, 0x928, 0xb78, 0x45d, 0xa17, 0x532, 0x9a6, 0x683, 0x8c9, 0x7ec, 0xec4, 0x1e1, 0xfab, 0x08e, 0xc1a, 0x33f, 0xd75, 0x250, 0x9d5, 0x6f0, 0x8ba, 0x79f, 0xb0b, 0x42e, 0xa64, 0x541, 0xc69 ]; // final format bits with mask: level 3 | mask var fmtword = [ 0x77c4, 0x72f3, 0x7daa, 0x789d, 0x662f, 0x6318, 0x6c41, 0x6976, //L 0x5412, 0x5125, 0x5e7c, 0x5b4b, 0x45f9, 0x40ce, 0x4f97, 0x4aa0, //M 0x355f, 0x3068, 0x3f31, 0x3a06, 0x24b4, 0x2183, 0x2eda, 0x2bed, //Q 0x1689, 0x13be, 0x1ce7, 0x19d0, 0x0762, 0x0255, 0x0d0c, 0x083b //H ]; // 4 per version: number of blocks 1,2; data width; ecc width var eccblocks = [ 1, 0, 19, 7, 1, 0, 16, 10, 1, 0, 13, 13, 1, 0, 9, 17, 1, 0, 34, 10, 1, 0, 28, 16, 1, 0, 22, 22, 1, 0, 16, 28, 1, 0, 55, 15, 1, 0, 44, 26, 2, 0, 17, 18, 2, 0, 13, 22, 1, 0, 80, 20, 2, 0, 32, 18, 2, 0, 24, 26, 4, 0, 9, 16, 1, 0, 108, 26, 2, 0, 43, 24, 2, 2, 15, 18, 2, 2, 11, 22, 2, 0, 68, 18, 4, 0, 27, 16, 4, 0, 19, 24, 4, 0, 15, 28, 2, 0, 78, 20, 4, 0, 31, 18, 2, 4, 14, 18, 4, 1, 13, 26, 2, 0, 97, 24, 2, 2, 38, 22, 4, 2, 18, 22, 4, 2, 14, 26, 2, 0, 116, 30, 3, 2, 36, 22, 4, 4, 16, 20, 4, 4, 12, 24, 2, 2, 68, 18, 4, 1, 43, 26, 6, 2, 19, 24, 6, 2, 15, 28, 4, 0, 81, 20, 1, 4, 50, 30, 4, 4, 22, 28, 3, 8, 12, 24, 2, 2, 92, 24, 6, 2, 36, 22, 4, 6, 20, 26, 7, 4, 14, 28, 4, 0, 107, 26, 8, 1, 37, 22, 8, 4, 20, 24, 12, 4, 11, 22, 3, 1, 115, 30, 4, 5, 40, 24, 11, 5, 16, 20, 11, 5, 12, 24, 5, 1, 87, 22, 5, 5, 41, 24, 5, 7, 24, 30, 11, 7, 12, 24, 5, 1, 98, 24, 7, 3, 45, 28, 15, 2, 19, 24, 3, 13, 15, 30, 1, 5, 107, 28, 10, 1, 46, 28, 1, 15, 22, 28, 2, 17, 14, 28, 5, 1, 120, 30, 9, 4, 43, 26, 17, 1, 22, 28, 2, 19, 14, 28, 3, 4, 113, 28, 3, 11, 44, 26, 17, 4, 21, 26, 9, 16, 13, 26, 3, 5, 107, 28, 3, 13, 41, 26, 15, 5, 24, 30, 15, 10, 15, 28, 4, 4, 116, 28, 17, 0, 42, 26, 17, 6, 22, 28, 19, 6, 16, 30, 2, 7, 111, 28, 17, 0, 46, 28, 7, 16, 24, 30, 34, 0, 13, 24, 4, 5, 121, 30, 4, 14, 47, 28, 11, 14, 24, 30, 16, 14, 15, 30, 6, 4, 117, 30, 6, 14, 45, 28, 11, 16, 24, 30, 30, 2, 16, 30, 8, 4, 106, 26, 8, 13, 47, 28, 7, 22, 24, 30, 22, 13, 15, 30, 10, 2, 114, 28, 19, 4, 46, 28, 28, 6, 22, 28, 33, 4, 16, 30, 8, 4, 122, 30, 22, 3, 45, 28, 8, 26, 23, 30, 12, 28, 15, 30, 3, 10, 117, 30, 3, 23, 45, 28, 4, 31, 24, 30, 11, 31, 15, 30, 7, 7, 116, 30, 21, 7, 45, 28, 1, 37, 23, 30, 19, 26, 15, 30, 5, 10, 115, 30, 19, 10, 47, 28, 15, 25, 24, 30, 23, 25, 15, 30, 13, 3, 115, 30, 2, 29, 46, 28, 42, 1, 24, 30, 23, 28, 15, 30, 17, 0, 115, 30, 10, 23, 46, 28, 10, 35, 24, 30, 19, 35, 15, 30, 17, 1, 115, 30, 14, 21, 46, 28, 29, 19, 24, 30, 11, 46, 15, 30, 13, 6, 115, 30, 14, 23, 46, 28, 44, 7, 24, 30, 59, 1, 16, 30, 12, 7, 121, 30, 12, 26, 47, 28, 39, 14, 24, 30, 22, 41, 15, 30, 6, 14, 121, 30, 6, 34, 47, 28, 46, 10, 24, 30, 2, 64, 15, 30, 17, 4, 122, 30, 29, 14, 46, 28, 49, 10, 24, 30, 24, 46, 15, 30, 4, 18, 122, 30, 13, 32, 46, 28, 48, 14, 24, 30, 42, 32, 15, 30, 20, 4, 117, 30, 40, 7, 47, 28, 43, 22, 24, 30, 10, 67, 15, 30, 19, 6, 118, 30, 18, 31, 47, 28, 34, 34, 24, 30, 20, 61, 15, 30 ]; // Galois field log table var glog = [ 0xff, 0x00, 0x01, 0x19, 0x02, 0x32, 0x1a, 0xc6, 0x03, 0xdf, 0x33, 0xee, 0x1b, 0x68, 0xc7, 0x4b, 0x04, 0x64, 0xe0, 0x0e, 0x34, 0x8d, 0xef, 0x81, 0x1c, 0xc1, 0x69, 0xf8, 0xc8, 0x08, 0x4c, 0x71, 0x05, 0x8a, 0x65, 0x2f, 0xe1, 0x24, 0x0f, 0x21, 0x35, 0x93, 0x8e, 0xda, 0xf0, 0x12, 0x82, 0x45, 0x1d, 0xb5, 0xc2, 0x7d, 0x6a, 0x27, 0xf9, 0xb9, 0xc9, 0x9a, 0x09, 0x78, 0x4d, 0xe4, 0x72, 0xa6, 0x06, 0xbf, 0x8b, 0x62, 0x66, 0xdd, 0x30, 0xfd, 0xe2, 0x98, 0x25, 0xb3, 0x10, 0x91, 0x22, 0x88, 0x36, 0xd0, 0x94, 0xce, 0x8f, 0x96, 0xdb, 0xbd, 0xf1, 0xd2, 0x13, 0x5c, 0x83, 0x38, 0x46, 0x40, 0x1e, 0x42, 0xb6, 0xa3, 0xc3, 0x48, 0x7e, 0x6e, 0x6b, 0x3a, 0x28, 0x54, 0xfa, 0x85, 0xba, 0x3d, 0xca, 0x5e, 0x9b, 0x9f, 0x0a, 0x15, 0x79, 0x2b, 0x4e, 0xd4, 0xe5, 0xac, 0x73, 0xf3, 0xa7, 0x57, 0x07, 0x70, 0xc0, 0xf7, 0x8c, 0x80, 0x63, 0x0d, 0x67, 0x4a, 0xde, 0xed, 0x31, 0xc5, 0xfe, 0x18, 0xe3, 0xa5, 0x99, 0x77, 0x26, 0xb8, 0xb4, 0x7c, 0x11, 0x44, 0x92, 0xd9, 0x23, 0x20, 0x89, 0x2e, 0x37, 0x3f, 0xd1, 0x5b, 0x95, 0xbc, 0xcf, 0xcd, 0x90, 0x87, 0x97, 0xb2, 0xdc, 0xfc, 0xbe, 0x61, 0xf2, 0x56, 0xd3, 0xab, 0x14, 0x2a, 0x5d, 0x9e, 0x84, 0x3c, 0x39, 0x53, 0x47, 0x6d, 0x41, 0xa2, 0x1f, 0x2d, 0x43, 0xd8, 0xb7, 0x7b, 0xa4, 0x76, 0xc4, 0x17, 0x49, 0xec, 0x7f, 0x0c, 0x6f, 0xf6, 0x6c, 0xa1, 0x3b, 0x52, 0x29, 0x9d, 0x55, 0xaa, 0xfb, 0x60, 0x86, 0xb1, 0xbb, 0xcc, 0x3e, 0x5a, 0xcb, 0x59, 0x5f, 0xb0, 0x9c, 0xa9, 0xa0, 0x51, 0x0b, 0xf5, 0x16, 0xeb, 0x7a, 0x75, 0x2c, 0xd7, 0x4f, 0xae, 0xd5, 0xe9, 0xe6, 0xe7, 0xad, 0xe8, 0x74, 0xd6, 0xf4, 0xea, 0xa8, 0x50, 0x58, 0xaf ]; // Galios field exponent table var gexp = [ 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1d, 0x3a, 0x74, 0xe8, 0xcd, 0x87, 0x13, 0x26, 0x4c, 0x98, 0x2d, 0x5a, 0xb4, 0x75, 0xea, 0xc9, 0x8f, 0x03, 0x06, 0x0c, 0x18, 0x30, 0x60, 0xc0, 0x9d, 0x27, 0x4e, 0x9c, 0x25, 0x4a, 0x94, 0x35, 0x6a, 0xd4, 0xb5, 0x77, 0xee, 0xc1, 0x9f, 0x23, 0x46, 0x8c, 0x05, 0x0a, 0x14, 0x28, 0x50, 0xa0, 0x5d, 0xba, 0x69, 0xd2, 0xb9, 0x6f, 0xde, 0xa1, 0x5f, 0xbe, 0x61, 0xc2, 0x99, 0x2f, 0x5e, 0xbc, 0x65, 0xca, 0x89, 0x0f, 0x1e, 0x3c, 0x78, 0xf0, 0xfd, 0xe7, 0xd3, 0xbb, 0x6b, 0xd6, 0xb1, 0x7f, 0xfe, 0xe1, 0xdf, 0xa3, 0x5b, 0xb6, 0x71, 0xe2, 0xd9, 0xaf, 0x43, 0x86, 0x11, 0x22, 0x44, 0x88, 0x0d, 0x1a, 0x34, 0x68, 0xd0, 0xbd, 0x67, 0xce, 0x81, 0x1f, 0x3e, 0x7c, 0xf8, 0xed, 0xc7, 0x93, 0x3b, 0x76, 0xec, 0xc5, 0x97, 0x33, 0x66, 0xcc, 0x85, 0x17, 0x2e, 0x5c, 0xb8, 0x6d, 0xda, 0xa9, 0x4f, 0x9e, 0x21, 0x42, 0x84, 0x15, 0x2a, 0x54, 0xa8, 0x4d, 0x9a, 0x29, 0x52, 0xa4, 0x55, 0xaa, 0x49, 0x92, 0x39, 0x72, 0xe4, 0xd5, 0xb7, 0x73, 0xe6, 0xd1, 0xbf, 0x63, 0xc6, 0x91, 0x3f, 0x7e, 0xfc, 0xe5, 0xd7, 0xb3, 0x7b, 0xf6, 0xf1, 0xff, 0xe3, 0xdb, 0xab, 0x4b, 0x96, 0x31, 0x62, 0xc4, 0x95, 0x37, 0x6e, 0xdc, 0xa5, 0x57, 0xae, 0x41, 0x82, 0x19, 0x32, 0x64, 0xc8, 0x8d, 0x07, 0x0e, 0x1c, 0x38, 0x70, 0xe0, 0xdd, 0xa7, 0x53, 0xa6, 0x51, 0xa2, 0x59, 0xb2, 0x79, 0xf2, 0xf9, 0xef, 0xc3, 0x9b, 0x2b, 0x56, 0xac, 0x45, 0x8a, 0x09, 0x12, 0x24, 0x48, 0x90, 0x3d, 0x7a, 0xf4, 0xf5, 0xf7, 0xf3, 0xfb, 0xeb, 0xcb, 0x8b, 0x0b, 0x16, 0x2c, 0x58, 0xb0, 0x7d, 0xfa, 0xe9, 0xcf, 0x83, 0x1b, 0x36, 0x6c, 0xd8, 0xad, 0x47, 0x8e, 0x00 ]; // Working buffers: // data input and ecc append, image working buffer, fixed part of image, run lengths for badness var strinbuf=[], eccbuf=[], qrframe=[], framask=[], rlens=[]; // Control values - width is based on version, last 4 are from table. var version, width, neccblk1, neccblk2, datablkw, eccblkwid; var ecclevel = 2; // set bit to indicate cell in qrframe is immutable. symmetric around diagonal function setmask(x, y) { var bt; if (x y) { bt = x; x = y; y = bt; } // y*y = 1+3+5... bt = y; bt *= y; bt += y; bt = 1; bt += x; framask[bt] = 1; } // enter alignment pattern - black to qrframe, white to mask (later black frame merged to mask) function putalign(x, y) { var j; qrframe[x + width * y] = 1; for (j = -2; j 2; j++) { qrframe[(x + j) + width * (y - 2)] = 1; qrframe[(x - 2) + width * (y + j + 1)] = 1; qrframe[(x + 2) + width * (y + j)] = 1; qrframe[(x + j + 1) + width * (y + 2)] = 1; } for (j = 0; j 2; j++) { setmask(x - 1, y + j); setmask(x + 1, y - j); setmask(x - j, y - 1); setmask(x + j, y + 1); } } //======================================================================== // Reed Solomon error correction // exponentiation mod N function modnn(x) { while (x = 255) { x -= 255; x = (x 8) + (x & 255); } return x; } var genpoly = []; // Calculate and append ECC data to data block. Block is in strinbuf, indexes to buffers given. function appendrs(data, dlen, ecbuf, eclen) { var i, j, fb; for (i = 0; i eclen; i++) strinbuf[ecbuf + i] = 0; for (i = 0; i dlen; i++) { fb = glog[strinbuf[data + i] ^ strinbuf[ecbuf]]; if (fb != 255) /* fb term is non-zero */ for (j = 1; j eclen; j++) strinbuf[ecbuf + j - 1] = strinbuf[ecbuf + j] ^ gexp[modnn(fb + genpoly[eclen - j])]; else for( j = ecbuf ; j ecbuf + eclen; j++ ) strinbuf[j] = strinbuf[j + 1]; strinbuf[ ecbuf + eclen - 1] = fb == 255 ? 0 : gexp[modnn(fb + genpoly[0])]; } } //======================================================================== // Frame data insert following the path rules // check mask - since symmetrical use half. function ismasked(x, y) { var bt; if (x y) { bt = x; x = y; y = bt; } bt = y; bt += y * y; bt = 1; bt += x; return framask[bt]; } //======================================================================== // Apply the selected mask out of the 8. function applymask(m) { var x, y, r3x, r3y; switch (m) { case 0: for (y = 0; y width; y++) for (x = 0; x width; x++) if (!((x + y) & 1) && !ismasked(x, y)) qrframe[x + y * width] ^= 1; break; case 1: for (y = 0; y width; y++) for (x = 0; x width; x++) if (!(y & 1) && !ismasked(x, y)) qrframe[x + y * width] ^= 1; break; case 2: for (y = 0; y width; y++) for (r3x = 0, x = 0; x width; x++, r3x++) { if (r3x == 3) r3x = 0; if (!r3x && !ismasked(x, y)) qrframe[x + y * width] ^= 1; } break; case 3: for (r3y = 0, y = 0; y width; y++, r3y++) { if (r3y == 3) r3y = 0; for (r3x = r3y, x = 0; x width; x++, r3x++) { if (r3x == 3) r3x = 0; if (!r3x && !ismasked(x, y)) qrframe[x + y * width] ^= 1; } } break; case 4: for (y = 0; y width; y++) for (r3x = 0, r3y = ((y 1) & 1), x = 0; x width; x++, r3x++) { if (r3x == 3) { r3x = 0; r3y = !r3y; } if (!r3y && !ismasked(x, y)) qrframe[x + y * width] ^= 1; } break; case 5: for (r3y = 0, y = 0; y width; y++, r3y++) { if (r3y == 3) r3y = 0; for (r3x = 0, x = 0; x width; x++, r3x++) { if (r3x == 3) r3x = 0; if (!((x & y & 1) + !(!r3x | !r3y)) && !ismasked(x, y)) qrframe[x + y * width] ^= 1; } } break; case 6: for (r3y = 0, y = 0; y width; y++, r3y++) { if (r3y == 3) r3y = 0; for (r3x = 0, x = 0; x width; x++, r3x++) { if (r3x == 3) r3x = 0; if (!(((x & y & 1) + (r3x && (r3x == r3y))) & 1) && !ismasked(x, y)) qrframe[x + y * width] ^= 1; } } break; case 7: for (r3y = 0, y = 0; y width; y++, r3y++) { if (r3y == 3) r3y = 0; for (r3x = 0, x = 0; x width; x++, r3x++) { if (r3x == 3) r3x = 0; if (!(((r3x && (r3x == r3y)) + ((x + y) & 1)) & 1) && !ismasked(x, y)) qrframe[x + y * width] ^= 1; } } break; } return; } // Badness coefficients. var N1 = 3, N2 = 3, N3 = 40, N4 = 10; // Using the table of the length of each run, calculate the amount of bad image // - long runs or those that look like finders; called twice, once each for X and Y function badruns(length) { var i; var runsbad = 0; for (i = 0; i = length; i++) if (rlens[i] = 5) runsbad += N1 + rlens[i] - 5; // BwBBBwB as in finder for (i = 3; i length - 1; i += 2) if (rlens[i - 2] == rlens[i + 2] && rlens[i + 2] == rlens[i - 1] && rlens[i - 1] == rlens[i + 1] && rlens[i - 1] * 3 == rlens[i] // white around the black pattern? Not part of spec && (rlens[i - 3] == 0 // beginning || i + 3 length // end || rlens[i - 3] * 3 = rlens[i] * 4 || rlens[i + 3] * 3 = rlens[i] * 4) ) runsbad += N3; return runsbad; } // Calculate how bad the masked image is - blocks, imbalance, runs, or finders. function badcheck() { var x, y, h, b, b1; var thisbad = 0; var bw = 0; // blocks of same color. for (y = 0; y width - 1; y++) for (x = 0; x width - 1; x++) if ((qrframe[x + width * y] && qrframe[(x + 1) + width * y] && qrframe[x + width * (y + 1)] && qrframe[(x + 1) + width * (y + 1)]) // all black || !(qrframe[x + width * y] || qrframe[(x + 1) + width * y] || qrframe[x + width * (y + 1)] || qrframe[(x + 1) + width * (y + 1)])) // all white thisbad += N2; // X runs for (y = 0; y width; y++) { rlens[0] = 0; for (h = b = x = 0; x width; x++) { if ((b1 = qrframe[x + width * y]) == b) rlens[h]++; else rlens[++h] = 1; b = b1; bw += b ? 1 : -1; } thisbad += badruns(h); } // black/white imbalance if (bw 0) bw = -bw; var big = bw; var count = 0; big += big 2; big = 1; while (big width * width) big -= width * width, count++; thisbad += count * N4; // Y runs for (x = 0; x width; x++) { rlens[0] = 0; for (h = b = y = 0; y width; y++) { if ((b1 = qrframe[x + width * y]) == b) rlens[h]++; else rlens[++h] = 1; b = b1; } thisbad += badruns(h); } return thisbad; } function genframe(instring) { var x, y, k, t, v, i, j, m; // find the smallest version that fits the string t = instring.length; version = 0; do { version++; k = (ecclevel - 1) * 4 + (version - 1) * 16; neccblk1 = eccblocks[k++]; neccblk2 = eccblocks[k++]; datablkw = eccblocks[k++]; eccblkwid = eccblocks[k]; k = datablkw * (neccblk1 + neccblk2) + neccblk2 - 3 + (version = 9); if (t = k) break; } while (version 40); // FIXME - insure that it fits insted of being truncated 
