Qt之自定义验证码控件

关于验证码

• 验证码必须随机生成。
• 验证码必须有一定的识别难度。

关于解决方案

• 随机产生目标验证码。
• 验证码中的字符颜色随机变化。
• 在验证码区域随机绘制噪点。
• 利用已有组件进行重新实现。

头文件

class Verification : public QPushButton
{
    Q_OBJECT
public:
    explicit Verification(QWidget *parent = nullptr);

    Qt::GlobalColor* getColor();

    void paintEvent(QPaintEvent *event);

    QString m_captcha;
    Qt::GlobalColor* m_color;
    QTimer *m_timer;
signals:

public slots:
    QString getCaptcha();
    void TimeoutSlot();
};

源文件

Verification::Verification(QWidget *parent) : QPushButton(parent)
{
    m_timer = new QTimer(this);
    qsrand(QTime::currentTime().second() * 1000 + QTime::currentTime().msec());
    m_captcha = getCaptcha();
    m_color = getColor();
    connect(m_timer,SIGNAL(timeout()),this,SLOT(TimeoutSlot()));
    m_timer->start(200);

    connect(this,SIGNAL(clicked(bool)),this,SLOT(getCaptcha()));
}

QString Verification::getCaptcha()
{
    QString ret = "";
    for(int i = 0; i < 4; i++){
        int c = (qrand() % 2) ? 'a' : 'A';
        ret += static_cast(c + qrand() % 26);
    }
    m_captcha = ret;
    return ret;
}

Qt::GlobalColor *Verification::getColor()
{
    static Qt::GlobalColor colors[4];
    for(int i = 0; i < 4; i++)
    {
        colors[i] = static_cast((qrand() % 16) + 2);
    }
    return colors;
}

void Verification::paintEvent(QPaintEvent *event)
{
    QPainter painter(this);
    painter.fillRect(0, 0, 84, 24, Qt::white);
    painter.setFont(QFont("Comic Sans MS"));

    //绘制噪点
    for(int i = 0; i < 100; i++){
        painter.setPen(m_color[i % 4]);
        painter.drawPoint(0 + (qrand() % 84), 0 + (qrand() % 24));
    }
    //绘制验证码
    for(int i = 0; i < 4; i++){
        painter.setPen(m_color[i]);
        painter.drawText(0 + 20 * i, 0, 20, 24, Qt::AlignCenter, QString(m_captcha[i]));
    }
}

void Verification::TimeoutSlot()
{
    m_color = getColor();
    update();
}