qt Creator 5.5.1如何为QGraphicsView添加背景

Question

如题，我继承了一个新类并重载了drawBackground，但是发现不行，求大神指点

Answer 1

setStyleSheet("background: transparent;border:0px");
setWindowFlags(Qt::FramelessWindowHint);

setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);