在Qt中旋转图像

#include <QApplication>
#include <QWidget>
#include <QPainter>
#include <QImage>

class RotatedImageWidget : public QWidget {
public:
    RotatedImageWidget(const QImage &image, qreal angle) : m_image(image), m_angle(angle) {}

protected:
    void paintEvent(QPaintEvent *event) override {
        QPainter painter(this);
        painter.translate(width() / 2, height() / 2);
        painter.rotate(m_angle);
        painter.drawImage(-m_image.width() / 2, -m_image.height() / 2, m_image);
    }

private:
    QImage m_image;
    qreal m_angle;
};

int main(int argc, char *argv[]) {
    QApplication app(argc, argv);

    QImage image("path/to/your/image.jpg");
    RotatedImageWidget widget(image, 45.0);
    widget.resize(800, 600);
    widget.show();

    return app.exec();
}

#include <QApplication>
#include <QLabel>
#include <QImage>
#include <QTransform>

int main(int argc, char *argv[]) {
    QApplication app(argc, argv);

    QImage image("path/to/your/image.jpg");
    QTransform transform;
    transform.rotate(45.0);
    QImage rotatedImage = image.transformed(transform);

    QLabel label;
    label.setPixmap(QPixmap::fromImage(rotatedImage));
    label.resize(800, 600);
    label.show();

    return app.exec();
}