```html
```
定义类的时候最好定义成canvas类，便于可以进行css样式调节。
字母和数字的组合(4个)
```js
let Mcaptcha = require('../../utils/mcaptcha.js');
onReady: function() {
var that = this;
var num = that.getRanNum();
// console.log(num)
this.setData({
num: num
});
new Mcaptcha({
el: 'canvas',
width: 80, // 对图形的宽高进行控制
height: 30,
code: num
});
},
getRanNum: function() {
var chars = 'ABCDEFGHJKMNPQRSTWXYZabcdefhijkmnprstwxyz2345678';
var pwd = '';
for (var i = 0; i < 4; i++) {
if (Math.random() < 48) {
pwd += chars.charAt(Math.random() * 48 - 1);
}
}
return pwd;
},
// mcaptcha.js
module.exports = class Mcaptcha {
constructor(options) {
this.options = options;
this.fontSize = options.height * 3 / 4;
this.init();
this.refresh(this.options.code);
}
init() {}, // 需要实现初始化方法，例如设置画布大小、生成随机字符等操作。在实际使用中需要根据具体需求进行修改和完善。
以下是重构后的代码：
```javascript
createCanvasContext(el) {
this.ctx = wx.createCanvasContext(el);
this.ctx.setTextBaseline("middle");
this.ctx.setFillStyle(this.randomColor(180, 240));
this.ctx.fillRect(0, 0, this.options.width, this.options.height);
}
randomColor(a, b) {
// 这里需要实现一个随机颜色的函数
}
randomNum(min, max) {
// 这里需要实现一个生成随机数的函数
}
refresh(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);
});
}
```
以下是重构后的内容：
```
this.ctx.rotate(-deg * Math.PI / 180);
this.ctx.translate(-dis, - this.options.height * 0.5);
this.ctx.draw();
}
randomNum(min, max) {
return Math.floor(Math.random() * (max - min) + min);
}
randomColor(min, max) {
let r = randomNum(min, max);
let g = randomNum(min, max);
let b = randomNum(min, max);
return `rgb(${r},${g},${b})`;
}
```
