LightGroupButton* sender = static_ cast＜LightGroupButton*＞(QObject::sender())；

When one Object emit One signal When , It's a sender, The system will record who is currently emit Out of this signal Of , So we can get which signal to send from the corresponding slot function  

There could be multiple Object Of signal Will be connected to the same signal( For example, more than one Button May be connect To a slot function onClick()), Therefore, it is necessary to judge which Object emit With this signal, according to sender Different to deal with different

QObject::Sender() Returns the pointer of the object that sent the signal , The return type is QObject *

The following example ：

void LightLibCreateWidget::slotEffectCBClicked()
{
    //  Set selection button 
    LightGroupButton* sender = static_cast<LightGroupButton*>(QObject::sender());
    m_iSelectBtnIndex = sender->getLightIndex();
}