qt实现验证码的代码与思路

#ifndef RANDVERIFYCODE_H
#define RANDVERIFYCODE_H

#include 
#include 
#include 
#include 
#include 

class randVerifyCode : public QWidget
{
    Q_OBJECT
public:
    explicit randVerifyCode(QWidget *parent = nullptr);
    void paintEvent(QPaintEvent *);
    void mousePressEvent(QMouseEvent *event);
    void generateRandNum();
    QString code;
signals:

public slots:

};

#endif // RANDVERIFYCODE_H

#include "randverifycode.h"
#include 
#include 
#include 
#include 
#include 
randVerifyCode::randVerifyCode(QWidget *parent)
    : QWidget{parent}
{
    //验证码窗口初始化
    this->setFixedSize(180,80);
    this->setStyleSheet("background-color:white;");


    //随机数种子初始化
    qsrand(QTime(0,0,0).secsTo(QTime::currentTime()));

    //生成随机数
    this->generateRandNum();

}

void randVerifyCode::generateRandNum()
{
    this->code.clear();
    for(int i = 0;i < 4;++i)
    {
        int num = qrand()%3;
        if(num == 0)
        {
            //数字
            this->code += QString::number(qrand()%10);
        }
        else if(num == 1)
        {
            //大写字母
            int temp = 'A';
            this->code += static_cast(temp + qrand()%26);
        }
        else if(num == 2)
        {
            //小写字母
            int temp = 'a';
            this->code += static_cast(temp + qrand()%26);
        }
    }
}

void randVerifyCode::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    QPen pen;
    QFont font("楷体",25,QFont::Bold,true);
    painter.setFont(font);

    //画点
    for(int i=0;i<100;i++)
    {
        pen = QPen(QColor(qrand()%256,qrand()%256,qrand()%256));
        painter.setPen(pen);
        painter.drawPoint(qrand()%180,qrand()%80);
    }

    //画线
    for(int i=0;i<5;i++)
    {
        pen = QPen(QColor(qrand()%256,qrand()%256,qrand()%256));
        painter.setPen(pen);
        painter.drawLine(qrand()%180,qrand()%80,qrand()%180,qrand()%80);
    }

    //绘制验证码
    for(int i=0;i<4;i++)
    {
        pen = QPen(QColor(qrand()%255,qrand()%255,qrand()%255));
        painter.setPen(pen);
        painter.drawText(15+35*i,10+qrand()%15,30,40,Qt::AlignCenter, QString(code[i]));
    }
}

void randVerifyCode::mousePressEvent(QMouseEvent *event)
{
    //重新生成验证码
    generateRandNum();
    //实时更新
    update();
}