QGraphicsItem不响应mouseReleaseEvent的问题

直接重写鼠标事件，遇到的问题是：只响应press事件，而move和release事件不响应。

解决方式是将item设为selectable或movable。

//构造函数中
this->setFlag(QGraphicsItem::ItemIsSelectable);
this->setAcceptedMouseButtons(Qt::LeftButton);
this->setAcceptHoverEvents(true);//重写hover事件需添加
void Rectangle::mousePressEvent(QGraphicsSceneMouseEvent *event)
{
    if (event->button() == Qt::LeftButton) {
        qDebug()<<"EVENT: "<<"MOUSE PRESS"<<endl;
    }
    BasicItemAbs::mousePressEvent(event);
}
void Rectangle::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
{
    qDebug()<<"EVENT: "<<"MOUSE MOVE"<<endl;
    BasicItemAbs::mouseMoveEvent(event);
}
void Rectangle::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
{
    if (event->button() == Qt::LeftButton) {
        qDebug()<<"EVENT: "<<"MOUSE RELEASE"<<endl;
    }
    BasicItemAbs::mouseReleaseEvent(event);
}