微信小程序中的图形验证码

可以在utils中新建一个mcaptcha.js

代码如下：

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 + ")";

}

}

 

在对于页面的js中引入mcaptcha.js

var Mcaptcha = require('../../../utils/mcaptcha.js');

 

/**

* 生命周期函数--监听页面初次渲染完成

*/

onReady: function () {

this.mcaptcha=new Mcaptcha({

el: 'canvas',

80,

height: 35,

createCodeImg: ""

});

},

。。。

//刷新验证码

onTap(){

this.mcaptcha.refresh();

},

 

//验证验证码

var res = this.mcaptcha.validate(this.data.imgCode);

if (this.data.imgCode == '' || this.data.imgCode==null) {

toast.showToast({ title: '请输入图形验证码' })

return;

}

if (!res) {

toast.showToast({ title: '图形验证码错误' })

return;

}

wxml页面：

<input type="text" id="code" name="codeImg" placeholder-class='C3' bindinput='codeImg' placeholder="请输入图形验证码" maxlength="4" value='{{imgCode}}'/>

<view style='position:relative;' bindtap="onTap">

<canvas style="160rpx;height:70rpx;position:absolute;right:0rpx;bottom:10rpx;text-align: center;z-index:9999;" canvas-id="canvas"></canvas>

</view>

 

效果：

 

 

参考：https://www.jianshu.com/p/064a80a3561a