获取场景缩略图的代码如下：

void chunzhongForm::getRenderPaint()
{QPixmap pixmap(SMALL_W,SMALL_H);pixmap.fill(Qt::transparent);QPainter painter(&pixmap);painter.setRenderHint(QPainter::Antialiasing);scene->render(&painter);pixmap.save(str,"png");dlg->setPixmap(pixmap);
}

需要指明画布的大小，如QPixmap pixmap(SMALL_W,SMALL_H)。调用场景的render（）函数来实现获取缩略图。