小程序图形验证码

1、在utils中新建一个mcaptcha.js

module.exports = class Mcaptcha {
  constructor(options) {
    this.options = options;
    this.fontSize = options.height * 3 / 6;
    this.init();
    this.refresh();
  }
  init() {
    this.ctx = wx.createCanvasContext(this.options.el);
    this.ctx.setTextBaseline("middle");
    this.ctx.setFillStyle(this.randomColor(180, 240));
  }
  refresh() {
    var code = '';
    var txtArr = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
    for (var i = 0; i < 4; i++) {
      code += txtArr[this.randomNum(0, txtArr.length)];
    }
    this.options.createCodeImg = code;
    let arr = (code + '').split('');
    if (arr.length === 0) {
      arr = ['e', 'r', 'r', 'o', 'r'];
    };
    let offsetLeft = this.options.width * 0.6 / (arr.length - 1);
    let marginLeft = this.options.width * 0.2;
    arr.forEach((item, index) => {
      this.ctx.setFillStyle(this.randomColor(0, 180));
      let size = this.randomNum(24, this.fontSize);
      this.ctx.setFontSize(size);
      let dis = offsetLeft * index + marginLeft - size * 0.3;
      let deg = this.randomNum(-30, 30);
      this.ctx.translate(dis, this.options.height * 0.5);
      this.ctx.rotate(deg * Math.PI / 180);
      this.ctx.fillText(item, 0, 0);
      this.ctx.rotate(-deg * Math.PI / 180);
      this.ctx.translate(-dis, -this.options.height * 0.5);
    })
    for (var i = 0; i < 4; i++) {
      this.ctx.strokeStyle = this.randomColor(40, 180);
      this.ctx.beginPath();
      this.ctx.moveTo(this.randomNum(0, this.options.width), this.randomNum(0, this.options.height));
      this.ctx.lineTo(this.randomNum(0, this.options.width), this.randomNum(0, this.options.height));
      this.ctx.stroke();
    }
    for (var i = 0; i < this.options.width / 4; i++) {
      this.ctx.fillStyle = this.randomColor(0, 255);
      this.ctx.beginPath();
      this.ctx.arc(this.randomNum(0, this.options.width), this.randomNum(0, this.options.height), 1, 0, 2 * Math.PI);
      this.ctx.fill();
    }
    this.ctx.draw();
  }
  validate(code) {
    var code = code.toLowerCase();
    var v_code = this.options.createCodeImg.toLowerCase();
    console.log(code)
    console.log(v_code.substring(v_code.length - 4))
    if (code == v_code.substring(v_code.length - 4)) {
      return true;
    } else {
      return false;
    }
  }
  randomNum(min, max) {
    return Math.floor(Math.random() * (max - min) + min);
  }
  randomColor(min, max) {
    let r = this.randomNum(min, max);
    let g = this.randomNum(min, max);
    let b = this.randomNum(min, max);
    return "rgb(" + r + "," + g + "," + b + ")";
  }
}

2、wxml页面：

<view class='flex-item'>
      <text>图形验证码：</text> 
      <input type="number"  bindinput="bindVerifyCode" maxlength="4" placeholder="请输入验证码" />
      <canvas class='canvas' canvas-id="canvas" bindtap='onTap'></canvas>
    </view>

3、样式

.canvas{
  width:160rpx;
  padding: 0 10rpx;
  height:70rpx;
  text-align: center;
}

4、在页面的js中引入mcaptcha.js

let Mcaptcha = require('../../utils/mcaptcha.js');
Page({
  data: {
    imgCode: ''
  },
  onLoad: function (options) {
    var that = this;
    this.mcaptcha = new Mcaptcha({
      el: 'canvas',
      width: 80,
      height: 35,
      createCodeImg: ""
    });
  },
  //刷新验证码
  onTap() {
    this.mcaptcha.refresh();
  },
  fnvavidate:function(){
    //验证验证码
    var res = this.mcaptcha.validate(this.data.imgCode);
    if (this.data.imgCode == '' || this.data.imgCode == null) {
      wx.showToast({ title:'请输入图形验证码'})
      return;
    }
    if (!res) {
      wx.showToast({ title:'图形验证码错误' })
      return;
    }
  },
})

5、效果图

111.png