#include <QApplication>
#include <QtWidgets>

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

    QGraphicsView w;
    QGraphicsScene s;
    w.setScene(&s);
    QGraphicsPixmapItem *imageItem = s.addPixmap(QPixmap());
    s.setSceneRect(0, 0, 400, 400);
    w.show();

    QObject::connect(QApplication::clipboard(), &QClipboard::dataChanged, [imageItem](){
        imageItem->setPixmap(QApplication::clipboard()->mimeData()->imageData().value<QPixmap>());
    });

    return a.exec();
}