绘制微信小程序验证码功能的实例代码

1.在 utils 文件中新建 mcaptcha.js 文件，写入以下代码：

module.exports = class Mcaptcha {
  //画板
 constructor(options) {
  this.options = options;
  this.fontSize = options.height * 3 / 4;
  this.init();
  this.refresh(this.options.code);
 }
 init() {
  this.ctx = wx.createCanvasContext(this.options.el);
  this.ctx.setTextBaseline("middle");
  this.ctx.setFillStyle(this.randomColor(180, 240));
  this.ctx.fillRect(0, 0, this.options.width, this.options.height);
 }
  //绘制彩图
 refresh(code) {
  let arr = (code + '').split('');
  let width = this.options.width;
  let height = this.options.height;
  let ctx = this.ctx;
  if (arr.length === 0) {
   arr = ['e', 'r', 'r','o','r'];
  };
  let offsetLeft = width * 0.6 / (arr.length - 1);
  let marginLeft = width * 0.2;
  arr.forEach((item, index) => {
   ctx.setFillStyle(this.randomColor(0, 180));
   let size = this.randomNum(24, this.fontSize);
   ctx.setFontSize(size);
   let dis = offsetLeft * index + marginLeft - size * 0.3;
   let deg = this.randomNum(-30, 30);
   ctx.translate(dis, height*0.5);
   ctx.rotate(deg * Math.PI / 180);
   ctx.fillText(item, 0, 0);
   ctx.rotate(-deg * Math.PI / 180);
   ctx.translate(-dis, -height * 0.5);
  })
  //绘制干扰线
  for (var i = 0; i < 2; i++) {
	  ctx.strokeStyle = this.randomColor(40, 180);
	  ctx.beginPath();
	  ctx.moveTo(this.randomNum(0, width), this.randomNum(0, height));
	  ctx.lineTo(this.randomNum(20, width), this.randomNum(2, height));
	  ctx.stroke();
  }
  //绘制干扰点
  for (var i = 0; i < 30; i++) {
	  ctx.fillStyle = this.randomColor(0, 255);
	  ctx.beginPath();
	  ctx.arc(this.randomNum(0, width), this.randomNum(0, height), 1, 0, 2 * Math.PI);
	  ctx.fill();
	 }
  ctx.draw();
 }
  //设置随机数的颜色
 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.在需要验证码的js文件中引入

let Mcaptcha = require("../../../utils/mcaptcha.js");

res.data 是要传到mcaptcha.js 中的 code 值，也就是验证码，可以随意写为如：“ho55”，“a2sd” 等等。我这里是从后台传过来的数据，（前人写的代码，不好改动，只在前端加上干扰线和彩图）。

new Mcaptcha({
  el: 'canvas',
  width: 100,
  height: 30,
  code: res.data
});

wxml 文件， bindtap="getImgYZM" 是 new Mcaptcha 的方法名，再次点击可以换验证码图片。

<view bindtap="getImgYZM" class="yzm">
  <canvas style="width:{{cvs.width}};height:{{cvs.height}};" canvas-id="canvas"></canvas>
</view>

如果是在前端设置随机数，可以在data:{} 里面写

data: {
   str:"0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,P,Q,R,S,T,U,V,W,X,Y,Z",
   randStr:""
 }
//获取随机数
var res = "";
for(var i = 0; i < str.length ; i ++) {
  var id = Math.ceil(Math.random()*35);
  res += chars[id];
}
return res;

这一步可不看，以下是后端C#语言产生随机数返给前端的代码：

using JobClass;
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Web;
using System.Web.SessionState;

namespace WebSite.pcode
{
  /// <summary>
  /// getcode 的摘要说明
  /// </summary>
  public class getcode : IHttpHandler, IRequiresSessionState
  {
    public void ProcessRequest(HttpContext context)
    {
      context.Response.ContentType = "text/plain";
      string str = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,P,Q,R,S,T,U,V,W,X,Y,Z";
      string randStr = "";
      //生成随机数 Random
      Random randobj = new Random();
      string[] arr = str.Split(',');
      for (int i = 0; i < 4; i++)
      {
        randStr += arr[randobj.Next(arr.Length)];
      }
      context.Response.Write(randStr);
      return;
    }
    public bool IsReusable
    {
      get
      {
        return false;
      }
    }
  }
}

到此这篇关于绘制微信小程序验证码功能的实例代码的文章就介绍到这了,更多相关微信小程序验证码内容请搜索三水点靠木以前的文章或继续浏览下面的相关文章希望大家以后多多支持三水点靠木！