Hello all !

1. Qt Signals And Slots Between Threads Online
2. Qt Signals And Slots Between Threads 2017
3. Signal And Slot In Qt
4. Qt Signal Slot With 2 Arguments
5. Qt Signal Slot Thread
6. Qt Signals And Slots Between Threads Chart
7. Qt Signal Slot Example

Qt provides the signals and slots framework which allows you to do just that and is thread-safe, allowing safe communication directly from running threads to your GUI frontend. Signals allow you to.emit values, which are then picked up elsewhere in your code by slot functions which have been linked with.connect. There is then also the free spins which often is Qt Signals And Slots Threads limited to a specific type of game. We always recommend the free cash since then you often have more freedom to select whatever slot you want to Qt Signals And Slots Threads play. The standard use-case of Signals & Slots is interacting with the UI from the code while remaining responsive. This is nothing more than a specific version of „communicating between threads“. Another benefit of using them is loosely coupled objects. The QObject emitting the Signal does not know the Slot- QObject and vice versa.

I have some difficulties to find an appropriate way to solve a problem of communication between objects in differents threads (although I already read the Signals/slots accross threads). Here is my problem:

I have an object a of class A living in a thread T1.
I have an object b of class B living in a thread T2.

Both objects a and b can emit signals and have slots to manage the signals emitted by the object living in the other thread (Object a has slots to manage signals from object b, and object b have slots to manage signals from object a).

Qt Signals And Slots Between Threads Online

Once I have moved the object to their respective threads, I connect the signals/slots using Qt::connect(..., Qt::QueuedConnection), but once the signals is emitted, the slot is never executed.

Qt Signals And Slots Between Threads 2017

I don't use Qt::DirectConnection (because it's quite the same that invoking directly the method, and I don't want this), and I would like to avoid to manage an event dispatcher or an event loop in the parent thread.

Does someone know how to use correctly the Qt threads in order to make the communication between signals/slots between objects living in different threads (none living in the main thread) ?

Thank you a lot for your answers !

Hi People,

I have a problem with Qt meta-type system and the signal and slot connections.
I try to connect a signal and slot with each other. The signal looks like this:

@
signals: void sigSaveFileName(QString&);
@

Signal And Slot In Qt

and the slot:
@
private slots: void slotPutSaveFileName(QString& name);
@

Before I connect those, I would like register the QString with qRegisterMetaType() method then call connect method:

@
qRegisterMetaType<QString>('QString');
connect(&_worker, &Worker::sigOpenFileName, this, &MainWindow::slotPutOpenFileName);
@

Qt Signal Slot With 2 Arguments

If I run my application, I watch the application output, and I get the following warning:
QObject::connect: Cannot queue arguments of type 'QString&'
(Make sure 'QString&' is registered using qRegisterMetaType().)
QObject::connect: Cannot queue arguments of type 'QString&'
(Make sure 'QString&' is registered using qRegisterMetaType().)

and doesn't happen anything :(

Qt Signal Slot Thread

Qt Signals And Slots Between Threads Chart

Can tell me somebody what I make wrong?

Qt Signal Slot Example

Regards,
Norbert