Update GUI from another object with 2 threads.

[jiapei100]

Hi, anda_skoa:

Thank you for your prompt reply... Yes. I am transport the image as a signal argument , and I'm using Qt::BlockingQueuedConnection.
If I use Qt:irectConnection, I always get the following error message, and nothing has been drawed on the MainWindow:

QPixmap: It is not safe to use pixmaps outside the GUI thread

Now, I changed my signal/slot now, and avoid using the image as a signal argument. And, I'm trying to use Qt::QueuedConnection as suggested by you, it seems all signals emitted by my code are queued there forever, and nothing has ever been drawn on GUI... During debugging, whenever I paused the program, the debugging pointer will point to the line this->m_threadGroup.join_all(); . the code patch is attached

void LVStream::start()
{
this->m_threadProducer = boost::thread(&LVStream:roducer, this);
this->m_threadConsumer = boost::thread(&LVStream::consumer, this);
this->m_threadGroup.add_thread(&this->m_threadProducer);
this->m_threadGroup.add_thread(&this->m_threadConsumer);
this->m_threadGroup.join_all();
}

Any further suggestions please?
Thank you very much.


Pei

Any specific reason why you are using a BlockingQueuedConnection and not a normal QueuedConnection (or simply AutoConnection which results in a QueuedConnection when being used across thread boundaries)?

Are you transporting the image as a signal argument?

Cheers,
_