QT实现简单验证码

主要思路：

在QT designer 中绘制QLabel控件

自定义类继承QLabel类，并提升至控件

提升至

生成随机数

重写paintEvent绘制图形

重写mousePressEvent刷新验证码

注意当窗口大小、焦点发生变化时均可触发paintEvent函数。

绘制控件

 在窗口中添加QLabel控件并布局

自定义验证码类

.h文件

 1 #pragma once
 2 #include <QLabel>
 3 #include <QPaintEvent>
 4 #include <QPainter>
 5 #include <QTime>
 6 class VerificationCodeLabel : public QLabel
 7 {
 8 public:
 9     VerificationCodeLabel(QWidget *parent = 0);
10     ~VerificationCodeLabel();
11 protected:
12     //重写绘制事件,以此来生成验证码
13     void paintEvent(QPaintEvent *event);
14     void mousePressEvent(QMouseEvent *ev);
15 private:
16     const int letter_number = 4;//产生字符的数量
17     int noice_point_number;//噪点的数量
18     //生成验证码
19     void produceVerificationCode();
20     //产生随机的字符
21     QChar produceRandomLetter();
22     //产生随机的颜色
23     void produceRandomColor();
24 
25     QChar *verificationCode;
26     QColor *colorArray;
27 };

.cpp文件

 1 VerificationCodeLabel::VerificationCodeLabel(QWidget *parent): QLabel(parent)
 2 {
 3     //生成随机种子
 4     qsrand(QTime::currentTime().second() * 1000 + QTime::currentTime().msec());
 5     colorArray = new QColor[letter_number];
 6     verificationCode = new QChar[letter_number];
 7     noice_point_number = this->width()*4;
 8 }
 9 
10 VerificationCodeLabel::~VerificationCodeLabel()
11 {
12 
13 }
14 //重写绘制事件,以此来生成验证码
15 void VerificationCodeLabel::paintEvent(QPaintEvent *event)
16 {
17     QPainter painter(this);
18     QPoint p;
19     //产生4个不同的字符
20     produceVerificationCode();
21     //产生4个不同的颜色
22     produceRandomColor();
23     //绘制验证码
24     for (int i = 0; i < letter_number; ++i)
25     {
26         p.setX(i*(this->width() / letter_number) + this->width() / 16);
27         p.setY(this->height()/1.5);
28         painter.setPen(colorArray[i]);
29         painter.drawText(p, QString(verificationCode[i]));
30     }
31     //绘制噪点
32     for (int j = 0; j < noice_point_number; ++j)
33     {
34         p.setX(qrand() % this->width());
35         p.setY(qrand() % this->height());
36         painter.setPen(colorArray[j % 4]);
37         painter.drawPoint(p);
38     }
39     return;
40 }
41 //这是一个用来生成验证码的函数
42 void VerificationCodeLabel::produceVerificationCode()
43 {
44     for (int i = 0; i < letter_number; ++i)
45         verificationCode[i] = produceRandomLetter();
46     return;
47 }
48 //产生一个随机的字符
49 QChar VerificationCodeLabel::produceRandomLetter()
50 {
51     QChar c;
52     int flag = qrand() % letter_number;
53     switch (flag)
54     {
55     case 0:
56         c = '0' + qrand() % 10;
57         break;
58     case 1:
59         c = 'A' + qrand() % 26; 
60         break;
61     case 2:
62         c = 'a' + qrand() % 26; 
63         break;
64     default:
65         c = '0' + qrand() % 10;
66         break;
67     }
68     return c;
69 }
70 //产生随机的颜色
71 void VerificationCodeLabel::produceRandomColor()
72 {
73     for (int i = 0; i < letter_number; ++i)
74         colorArray[i] = QColor(qrand() % 255, qrand() % 255, qrand() % 255);
75     return;
76 }
77 
78 void VerificationCodeLabel::mousePressEvent(QMouseEvent *ev)
79 {
80     update();
81 }

自定义类提升至控件

运行结果

 参考：

https://blog.csdn.net/wjh_init/article/details/79163275