connect时槽函数不能加this

connect(this->m_timer, SIGNAL(timeout()), this, SLOT(this->onTimerSnapSlot()));

添加槽之后，不能connect的时候不能使用this调用，这里无法解析this->onTimerSnapSlot()

只能这样写

connect(this->m_timer, SIGNAL(timeout()), this, SLOT(onTimerSnapSlot()));