似乎不可能使用QPainter (或任何其他方法)来旋转自定义QGraphicsItem。

#include <QGraphicsItem>
#include <QPainter>

class CustomGraphicsItem : public QGraphicsItem
{
public:
    CustomGraphicsItem(QGraphicsItem* parent = nullptr) : QGraphicsItem(parent), rotationAngle(0) {}

    QRectF boundingRect() const override
    {
        return QRectF(-50, -50, 100, 100); // 自定义图形项的边界矩形
    }

    void paint(QPainter* painter, const QStyleOptionGraphicsItem* option, QWidget* widget) override
    {
        Q_UNUSED(option);
        Q_UNUSED(widget);

        painter->setRenderHint(QPainter::Antialiasing); // 设置抗锯齿

        painter->rotate(rotationAngle); // 旋转绘制操作

        // 绘制自定义图形项
        painter->setPen(Qt::black);
        painter->setBrush(Qt::red);
        painter->drawRect(-50, -50, 100, 100);
    }

    void rotate(qreal angle)
    {
        rotationAngle = angle;
        update(); // 触发重绘
    }

private:
    qreal rotationAngle;
};