Five connection modes of QT signal and slot

qt Five connection modes of signal and slot ：
1. Default connection ： If it is on the same thread, it is equivalent to direct connection , In different threads, it is equivalent to queue connection
2. Direct connection ： Where is the signal , On which thread （ It is best to use only in the same thread ）
3. Queue connection ： Where the slot is, the thread executes （ Slot functions do not execute immediately , The slot function will not be executed until the currently executed function of the receiver is executed ）
4. Blocking queue connections ： （ The slot function is called at the same time as the queue connection , It's just that the thread of the sender will block , Until the slot function runs , Sender and receiver must not be on the same thread ）
5.Qt::UniqueConnect The only connection , A signal can only have one slot connection , Multiple failures can be used | Combined with the above four

1. The thread of an object is the thread when the object is created , Whether the definition of the object is saved in that thread ;

　　 For example thread1 A new thread is opened in thread2, that thread2 Objects are defined in thread1 Medium , namely thread2 The object itself belongs to thread1 Of , And in the thread2 Of run The object defined in the function belongs to thread2 Of