小程序生成二维码和条形码
由于2023.10.27再次使用到小程序生成二维码的功能，因为本片内容有些冗余，所以另写一篇简化版的微信小程序生成二维码的功能使用步骤。
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 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）
开始：
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" /> </view>
utils.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 }
在方法中的使用
举例：（code要从后台获取） const code = '1221334122546765342'; toBarcode('barcode', code, 680, 200); toQrcode('qrcode', code, 420, 420); const codeStr = `${code.slice(0, 4)}****${code.slice(20)}`;
2023.10.27 补充wx.createCanvasContext已被官方弃用，可以改为一下方法使用，
<canvas id="qrcode" />
import qrcode from '../../utils/qrcode' //引入qrcode.js文件 wx.createSelectorQuery().select('#qrcode').context(function(res){ let code = '111' qrcode.api.draw(code, { ctx: res.context, width:170, height:170, }) }).exec()
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
})
}
})
上文中使用到的插件代码：
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 table function 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 color Graphics.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 width = 17 + 4 * version; // allocate, clear and setup data structures v = datablkw + (datablkw + eccblkwid) * (neccblk1 + neccblk2) + neccblk2; for( t = 0; t < v; t++ ) eccbuf[t] = 0; strinbuf = instring.slice(0); for( t = 0; t < width * width; t++ ) qrframe[t] = 0; for( t = 0 ; t < (width * (width + 1) + 1) / 2; t++) framask[t] = 0; // insert finders - black to frame, white to mask for (t = 0; t < 3; t++) { k = 0; y = 0; if (t == 1) k = (width - 7); if (t == 2) y = (width - 7); qrframe[(y + 3) + width * (k + 3)] = 1; for (x = 0; x < 6; x++) { qrframe[(y + x) + width * k] = 1; qrframe[y + width * (k + x + 1)] = 1; qrframe[(y + 6) + width * (k + x)] = 1; qrframe[(y + x + 1) + width * (k + 6)] = 1; } for (x = 1; x < 5; x++) { setmask(y + x, k + 1); setmask(y + 1, k + x + 1); setmask(y + 5, k + x); setmask(y + x + 1, k + 5); } for (x = 2; x < 4; x++) { qrframe[(y + x) + width * (k + 2)] = 1; qrframe[(y + 2) + width * (k + x + 1)] = 1; qrframe[(y + 4) + width * (k + x)] = 1; qrframe[(y + x + 1) + width * (k + 4)] = 1; } } // alignment blocks if (version > 1) { t = adelta[version]; y = width - 7; for (;;) { x = width - 7; while (x > t - 3) { putalign(x, y); if (x < t) break; x -= t; } if (y <= t + 9) break; y -= t; putalign(6, y); putalign(y, 6); } } // single black qrframe[8 + width * (width - 8)] = 1; // timing gap - mask only for (y = 0; y < 7; y++) { setmask(7, y); setmask(width - 8, y); setmask(7, y + width - 7); } for (x = 0; x < 8; x++) { setmask(x, 7); setmask(x + width - 8, 7); setmask(x, width - 8); } // reserve mask-format area for (x = 0; x < 9; x++) setmask(x, 8); for (x = 0; x < 8; x++) { setmask(x + width - 8, 8); setmask(8, x); } for (y = 0; y < 7; y++) setmask(8, y + width - 7); // timing row/col for (x = 0; x < width - 14; x++) if (x & 1) { setmask(8 + x, 6); setmask(6, 8 + x); } else { qrframe[(8 + x) + width * 6] = 1; qrframe[6 + width * (8 + x)] = 1; } // version block if (version > 6) { t = vpat[version - 7]; k = 17; for (x = 0; x < 6; x++) for (y = 0; y < 3; y++, k--) if (1 & (k > 11 ? version >> (k - 12) : t >> k)) { qrframe[(5 - x) + width * (2 - y + width - 11)] = 1; qrframe[(2 - y + width - 11) + width * (5 - x)] = 1; } else { setmask(5 - x, 2 - y + width - 11); setmask(2 - y + width - 11, 5 - x); } } // sync mask bits - only set above for white spaces, so add in black bits for (y = 0; y < width; y++) for (x = 0; x <= y; x++) if (qrframe[x + width * y]) setmask(x, y); // convert string to bitstream // 8 bit data to QR-coded 8 bit data (numeric or alphanum, or kanji not supported) v = strinbuf.length; // string to array for( i = 0 ; i < v; i++ ) eccbuf[i] = strinbuf.charCodeAt(i); strinbuf = eccbuf.slice(0); // calculate max string length x = datablkw * (neccblk1 + neccblk2) + neccblk2; if (v >= x - 2) { v = x - 2; if (version > 9) v--; } // shift and repack to insert length prefix i = v; if (version > 9) { strinbuf[i + 2] = 0; strinbuf[i + 3] = 0; while (i--) { t = strinbuf[i]; strinbuf[i + 3] |= 255 & (t << 4); strinbuf[i + 2] = t >> 4; } strinbuf[2] |= 255 & (v << 4); strinbuf[1] = v >> 4; strinbuf[0] = 0x40 | (v >> 12); } else { strinbuf[i + 1] = 0; strinbuf[i + 2] = 0; while (i--) { t = strinbuf[i]; strinbuf[i + 2] |= 255 & (t << 4); strinbuf[i + 1] = t >> 4; } strinbuf[1] |= 255 & (v << 4); strinbuf[0] = 0x40 | (v >> 4); } // fill to end with pad pattern i = v + 3 - (version < 10); while (i < x) { strinbuf[i++] = 0xec; // buffer has room if (i == x) break; strinbuf[i++] = 0x11; } // calculate and append ECC // calculate generator polynomial genpoly[0] = 1; for (i = 0; i < eccblkwid; i++) { genpoly[i + 1] = 1; for (j = i; j > 0; j--) genpoly[j] = genpoly[j] ? genpoly[j - 1] ^ gexp[modnn(glog[genpoly[j]] + i)] : genpoly[j - 1]; genpoly[0] = gexp[modnn(glog[genpoly[0]] + i)]; } for (i = 0; i <= eccblkwid; i++) genpoly[i] = glog[genpoly[i]]; // use logs for genpoly[] to save calc step // append ecc to data buffer k = x; y = 0; for (i = 0; i < neccblk1; i++) { appendrs(y, datablkw, k, eccblkwid); y += datablkw; k += eccblkwid; } for (i = 0; i < neccblk2; i++) { appendrs(y, datablkw + 1, k, eccblkwid); y += datablkw + 1; k += eccblkwid; } // interleave blocks y = 0; for (i = 0; i < datablkw; i++) { for (j = 0; j < neccblk1; j++) eccbuf[y++] = strinbuf[i + j * datablkw]; for (j = 0; j < neccblk2; j++) eccbuf[y++] = strinbuf[(neccblk1 * datablkw) + i + (j * (datablkw + 1))]; } for (j = 0; j < neccblk2; j++) eccbuf[y++] = strinbuf[(neccblk1 * datablkw) + i + (j * (datablkw + 1))]; for (i = 0; i < eccblkwid; i++) for (j = 0; j < neccblk1 + neccblk2; j++) eccbuf[y++] = strinbuf[x + i + j * eccblkwid]; strinbuf = eccbuf; // pack bits into frame avoiding masked area. x = y = width - 1; k = v = 1; // up, minus /* inteleaved data and ecc codes */ m = (datablkw + eccblkwid) * (neccblk1 + neccblk2) + neccblk2; for (i = 0; i < m; i++) { t = strinbuf[i]; for (j = 0; j < 8; j++, t <<= 1) { if (0x80 & t) qrframe[x + width * y] = 1; do { // find next fill position if (v) x--; else { x++; if (k) { if (y != 0) y--; else { x -= 2; k = !k; if (x == 6) { x--; y = 9; } } } else { if (y != width - 1) y++; else { x -= 2; k = !k; if (x == 6) { x--; y -= 8; } } } } v = !v; } while (ismasked(x, y)); } } // save pre-mask copy of frame strinbuf = qrframe.slice(0); t = 0; // best y = 30000; // demerit // for instead of while since in original arduino code // if an early mask was "good enough" it wouldn't try for a better one // since they get more complex and take longer. for (k = 0; k < 8; k++) { applymask(k); // returns black-white imbalance x = badcheck(); if (x < y) { // current mask better than previous best? y = x; t = k; } if (t == 7) break; // don't increment i to a void redoing mask qrframe = strinbuf.slice(0); // reset for next pass } if (t != k) // redo best mask - none good enough, last wasn't t applymask(t); // add in final mask/ecclevel bytes y = fmtword[t + ((ecclevel - 1) << 3)]; // low byte for (k = 0; k < 8; k++, y >>= 1) if (y & 1) { qrframe[(width - 1 - k) + width * 8] = 1; if (k < 6) qrframe[8 + width * k] = 1; else qrframe[8 + width * (k + 1)] = 1; } // high byte for (k = 0; k < 7; k++, y >>= 1) if (y & 1) { qrframe[8 + width * (width - 7 + k)] = 1; if (k) qrframe[(6 - k) + width * 8] = 1; else qrframe[7 + width * 8] = 1; } // return image return qrframe; } var _canvas = null, _size = null; var api = { get ecclevel () { return ecclevel; }, set ecclevel (val) { ecclevel = val; }, get size () { return _size; }, set size (val) { _size = val }, get canvas () { return _canvas; }, set canvas (el) { _canvas = el; }, getFrame: function (string) { return genframe(string); }, draw: function (string, canvas, size, ecc) { ecclevel = ecc || ecclevel; canvas = canvas || _canvas; if (!canvas) { console.warn('No canvas provided to draw QR code in!') return; } size = size || _size || Math.min(canvas.width, canvas.height); var frame = genframe(string), ctx = canvas.ctx, px = Math.round(size / (width + 8)); var roundedSize = px * (width + 8), offset = Math.floor((size - roundedSize) / 2); size = roundedSize; ctx.clearRect(0, 0, canvas.width, canvas.height); ctx.setFillStyle('#000000'); for (var i = 0; i < width; i++) { for (var j = 0; j < width; j++) { if (frame[j * width + i]) { ctx.fillRect(px * (4 + i) + offset, px * (4 + j) + offset, px, px); } } } ctx.draw(); } } module.exports = { api: api } })()
另一种生成二维码和条形码的方法：安装wxbarcode（待学习）
