起源：最近小程序需要涉及到一些推广方面的功能，所以要写一个动态生成二维码用户进行下载分享，写完之后受益良多，特此来分享一下；
一.微信小程序动态生成保存二维码
wxml:
<canvas style="width: 350rpx;height: 350rpx;background:#f1f1f1;" canvas-id="mycanvas"/>
js:
// pages/qrcode/qrcode.js var QR = require("../../utils/qrcode.js"); Page({ data: { name:"lishi", placeholder: ‘https://www.xxxxxx.com/xxxx/index.html?name=lishi‘//默认二维码生成文本 }, //动态生成二维码 onLoad: function (options) { // 页面初始化 options为页面跳转所带来的参数 var size = this.setCanvasSize();//动态设置画布大小 var initUrl = this.data.placeholder; this.createQrCode(initUrl, "mycanvas", size.w, size.h); }, //适配不同屏幕大小的canvas setCanvasSize: function () { var size = {}; try { var res = wx.getSystemInfoSync(); var scale = 350 / 175;//不同屏幕下canvas的适配比例；设计稿是750宽 var width = res.windowWidth / scale; var height = width;//canvas画布为正方形 size.w = width; size.h = height; } catch (e) { // Do something when catch error console.log("获取设备信息失败" + e); } return size; }, createQrCode: function (url, canvasId, cavW, cavH) { //调用插件中的draw方法，绘制二维码图片 QR.api.draw(url, canvasId, cavW, cavH); }, // 下载二维码 downloadCode: function() { wx.downloadFile({ url: ‘https://www.xxxxxx.cn/wxaaaa/code.png‘, success: function(res) { var filePath = res.tempFilePath wx.saveImageToPhotosAlbum({ filePath: filePath, success: function(res) { wx.showToast({ title: ‘图片保存成功‘, icon: ‘success‘, duration: 2000 //持续的时间 }) } }) }, fail: function(err) { console.log(err) } }) } })
注意：二维码地址和下载图片地址域名需要配置好，其次，这数据是通过接口获取的，博主这里展示写的是死数据；
二.qrcode.js
!(function () { // alignment pattern var adelta = [ 0, 11, 15, 19, 23, 27, 31, 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 qrframe; } var _canvas = 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); }, //这里的utf16to8(str)是对Text中的字符串进行转码，让其支持中文 utf16to8: function (str) { var out, i, len, c; out = ""; len = str.length; for (i = 0; i < len; i++) { c = str.charCodeAt(i); if ((c >= 0x0001) && (c <= 0x007F)) { out += str.charAt(i); } else if (c > 0x07FF) { out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F)); out += String.fromCharCode(0x80 | ((c >> 6) & 0x3F)); out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F)); } else { out += String.fromCharCode(0xC0 | ((c >> 6) & 0x1F)); out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F)); } } return out; }, /** * 新增$this参数，传入组件的this,兼容在组件中生成 */ draw: function (str, canvas, cavW, cavH, $this, ecc) { var that = this; ecclevel = ecc || ecclevel; canvas = canvas || _canvas; if (!canvas) { console.warn(‘No canvas provided to draw QR code in!‘) return; } var size = Math.min(cavW, cavH); str = that.utf16to8(str);//增加中文显示 var frame = that.getFrame(str), // 组件中生成qrcode需要绑定this ctx = wx.createCanvasContext(canvas,$this), px = Math.round(size / (width + 8)); var roundedSize = px * (width + 8), offset = Math.floor((size - roundedSize) / 2); size = roundedSize; //ctx.clearRect(0, 0, cavW, cavW); ctx.setFillStyle(‘#ffffff‘) ctx.fillRect(0, 0, cavW, cavW); 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 } // exports.draw = api; })();
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