9、Qt使用随机验证码

一、新建项目

创建一个"Qt Widget Application"项目，基类选择“QMainWindow”

二、自定义CaptchaLabel类

右击项目名，选择"Add New...”

C++ -> C++Class，点击“Choose”

更改类名CaptchaLabel，添加基类QLabel，点击“下一步”

默认，点击完成

更改captchalabel.h代码如下

#ifndef CAPTCHALABEL_H#define CAPTCHALABEL_H#include <QObject>#include <QLabel>class CaptchaLabel : public QLabel{public:explicit CaptchaLabel(QWidget* parent = nullptr);//获取随机数QString getRandNumber() { return m_randNumber; }void generateRandNumber(int num = 4);  //生成随机数protected:void paintEvent(QPaintEvent *event);  //绘制void mousePressEvent(QMouseEvent *event);  //鼠标按下private:QString m_randNumber;  //随机数};#endif // CAPTCHALABEL_H

更改captchalabel.cpp代码如下

#include "captchalabel.h"
#include <QDebug>
#include <QRandomGenerator>
#include <QTimer>
#include <QPainter>
#include <QTime>CaptchaLabel::CaptchaLabel(QWidget *parent) : QLabel(parent)
{this->setMinimumSize(100, 30);  //设置最小大小this->setStyleSheet("background-color:white;");  //白色背景//随机数种子初始化qsrand(QTime(0,0,0).secsTo(QTime::currentTime()));//生成随机数generateRandNumber();
}/**
* @brief CaptchaLabel::generateRandNum 生成随机数，默认是四个数
* @param num
*/
void CaptchaLabel::generateRandNumber(int num)
{m_randNumber.clear();for(int i = 0; i < num; i++){int num = qrand() % 3;if(num == 0)  //数字{m_randNumber += QString::number(qrand()%10);}else if(num == 1)  //大写字母{int temp = 'A';m_randNumber += static_cast<QChar>(temp + qrand()%26);}else if(num == 2)  //小写字母{int temp = 'a';m_randNumber += static_cast<QChar>(temp + qrand()%26);}}
}/**
* @brief CaptchaLabel::paintEvent 绘制验证码
*/
void CaptchaLabel::paintEvent(QPaintEvent *)
{QPainter painter(this);int num = m_randNumber.size();  //几个随机数int width = this->width();int height = this->height();//设置字体int size = (width/num) < height ? (width/num) : height;QFont font;font.setPixelSize(size);  //设置字体大小font.setItalic(true);  //设置字体倾斜font.setFamily(QString("楷体"));painter.setFont(font);  //若设置字体加粗，有的随机数会显示不全QPen pen;//绘制随机数for(int i = 0; i < num; i++){pen = QPen(QColor(qrand()%255, qrand()%255, qrand()%255));painter.setPen(pen);int y = (height-5-size) <= 0 ? 0 : (qrand()%(height-5-size));QRectF rect(width/num*i, y, width/num, size);//painter.drawRect(rect);  //测试时，查看矩形的位置及大小//在矩形rect中绘制大小为size的随机数painter.drawText(rect, Qt::AlignHCenter|Qt::AlignBottom, m_randNumber.at(i));}//绘制干扰点for(int i = 0; i < (num*25); i++){pen = QPen(QColor(qrand()%256, qrand()%256, qrand()%256));painter.setPen(pen);painter.drawPoint(qrand()%width, qrand()%height);}//绘制干扰线for(int i = 0; i < num; i++){pen = QPen(QColor(qrand()%256, qrand()%256, qrand()%256));painter.setPen(pen);painter.drawLine(qrand()%width, qrand()%height, qrand()%width, qrand()%height);}
}/*** @brief CaptchaLabel::mousePressEvent 鼠标点击时更换随机数* @param event*/
void CaptchaLabel::mousePressEvent(QMouseEvent *event){Q_UNUSED(event);//重新生成验证码generateRandNumber();//实时更新update();
}