轉【微信小程序 四】二維碼生成／掃描二維碼

原文：https://blog.csdn.net/xbw12138/article/details/75213274

前端 
二維碼生成 
二維碼要求：每分鐘刷新一次，模擬了個雞肋，添加了個按分鐘顯示的時間加在二維碼中，起到刷新的作用，在onshow中每次打開界面就會刷新顯示

var QR = require("../../utils/qrcode.js");
var util = require("../../utils/util.js");
data: {
    qrMsg: '',
    recognizeMsg: '',
    isShowMsg: false,
    isShowResult: false,
    showClear: true,
    qrlogin :false,
  },
onShow: function () {
    var that=this;
    this.setData({
      isShowMsg: false,
      isShowResult: true,
    })
    // 頁面顯示，用戶已註冊
   if (getApp().globalData.userSign == 1) {
     that.setData({
       qrlogin: true,
     })
     //存儲openid
      wx.getStorage({
        key: 'openid',
        success: function (res) {
          var openid = res.data;
          //加入分鐘，每分鐘刷新一次二維碼
          QR.qrApi.draw('wechat@'+openid + '@' + util.formatTimeQrcodeChange(new Date), 'mycanvas', 300, 300)
        }
      })
   } else if (getApp().globalData.userSign == 2){
      that.setData({
        qrlogin:false,
      })
    }
  },

---

掃描二維碼

recognizeCode: function () {
    this.setData({
      isShowMsg: true,
      isShowResult: false,
      recognizeMsg: "",
    })
    var that = this
    //小程序API
    wx.scanCode({
      //掃描條形碼ISBN
      success: function (res) {
        // success
        console.log('https://book.douban.com/subject/' + res.result+'/');
        var url = 'https://book.douban.com/subject/' + res.result + '/';
        wx.navigateTo({
          url: '../desc/desc?url=' + url
        })
      },
      fail: function () {
        // fail
      },
      complete: function () {
        // complete
      }
    })
  },

---

utils.js中添加以下代碼

function formatTimeQrcodeChange(date) {
  var year = date.getFullYear()
  var month = date.getMonth() + 1
  var day = date.getDate()

  var hour = date.getHours()
  var minute = date.getMinutes()
  //按分鐘顯示，去掉秒
  //var second = date.getSeconds()
  return [year, month, day].map(formatNumber).join('/') + ' ' + [hour, minute].map(formatNumber).join(':')
}

---

qrcode.js

var QR = (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,