Qt 制作验证码

#include <QRandomGenerator>
#include <QPainterPath>
#include <QPainter>

// 生成随机数
int r(int a,int b=0){
    return b ? QRandomGenerator::global()->bounded(a, b)
             : QRandomGenerator::global()->bounded(a);
}

// 生成随机多边形路径
QPainterPath createRandomPolygon(int width, int height) {
    QPainterPath path;
    int points = r(1, 7);
    QPointF center(r(width),r(height));

    for (int i = 0; i < points; ++i) {
        qreal radius = 1.0*r(3, 20);
        qreal angle = 2 * M_PI * i / points;
        QPointF pt = center + QPointF(radius * cos(angle), radius * sin(angle));
        if (i == 0) path.moveTo(pt);
        else path.lineTo(pt);
    }
    path.closeSubpath();
    return path;
}

void MainWindow::genRandomPixmap()
{
    // 生成随机4位数
    QString numberStr = QString::number(r(1000, 10000));

    // 创建画布
    QPixmap pixmap(ui->lbCode->size());
    pixmap.fill(Qt::white);
    QPainter painter(&pixmap);
    painter.setRenderHint(QPainter::Antialiasing);

    // 字体设置
    QFont baseFont("Arial", 23, QFont::Bold);
    painter.setFont(baseFont);

    // 动态计算字符间距（考虑旋转扩展）
    QFontMetrics fm(baseFont);
    int charSpacing = fm.horizontalAdvance('0') * 1.4; // 基础间距

    // 计算安全绘制区域
    auto w = pixmap.width();
    auto h = pixmap.height();
    // 绘制每个字符
    for (int i = 0; i < numberStr.size(); ++i) {
        painter.save();

        // 随机颜色（避免过浅）
        QColor textColor(r(10, 210), r(10, 210),r(10, 210) );
        painter.setPen(textColor);

        // 获取字符尺寸
        QRect charRect = fm.boundingRect(numberStr[i]);

        // 生成随机变换参数
        qreal angle = r(-30, 30);
        qreal centerX = i*charSpacing + (charRect.width() >> 1) + 11;
        qreal centerY = h >> 1;
        qreal scaleX = 1.0 + 0.01*r(-15, 15); // X缩放
        qreal scaleY = 1.0 + 0.01*r(-15, 15); // Y缩放
        qreal shearX = 0.1*r(-5, 5);  // X倾斜
        qreal shearY = 0.1*r(-1,1);   // Y倾斜

        // 设置变换（以字符中心为旋转点）
        QTransform transform;
        transform.translate(centerX, centerY);
        transform.rotate(angle);
        transform.scale(scaleX, scaleY);     // 缩放
        transform.shear(shearX, shearY);     // 倾斜
        transform.translate(-charRect.width()/2, charRect.height()>> 1); // 对齐基线
        painter.setTransform(transform);

        // 添加位置抖动（限制在安全区）
        QPointF offset(r(-2,2), r(-2,2) );
        painter.drawText(offset, QString(numberStr[i]));

        painter.restore();
    }
    // 增强效果
    // 添加干扰线（可选）
    for (int i = 0; i <5; ++i) {
        painter.setPen(QColor(r(240), r(240), r(240), r(150, 250)));
        painter.drawLine(
            r(w), r(h),
            r(w), r(h)
        );
    }
    // 添加随机多边形（可选）
    for (int i = 0; i <5; ++i) {
        QPainterPath path = createRandomPolygon(w, h);
        painter.setPen(QColor(r(240), r(240), r(240), r(150, 250)));
        painter.drawPath(path);
    }

    ui->lbCode->setPixmap(pixmap);
}