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Hi to all!
I try to make my first multithreaded program. I use a linux system, but I don't think that has to do with anything. It happens that I don't have a past experience with threads. By now I didn't had to use but the main thread.
Can you pls direct me to the right direction. Maybe a tutorial or some guidelines.
Thank you for your time
A good point to start is always the documentation of Qt: Thread Support in Qt. And then ervery book for Qt handles threads.
ok. So as far as I understand I have to subclass my class from QThread. But what if I want to subclass it from another custom class.
In order to be more specific...
I read the data from a list file, then I process the data to produce an image. But I want to have a periodical check or new data. My first thought was to create a new thread which will be responsible of doing this check and then provide the new data to the process class.
That's right,Quote:
Originally Posted by ^Nisok^
If the custom class is a subclass of QThread then that's also fine. Or you can subclass from QThread and the other class...Quote:
But what if I want to subclass it from another custom class.
If your check for new data is quick (I guess so) just use a timer inside your main app. If data chanced use/fire a worker thread .Quote:
Originally Posted by ^Nisok^
You also can use signal and slots across the thread borderQuote:
My first thought was to create a new thread which will be responsible of doing this check and then provide the new data to the process class.
If I create a l class from a parent which runs on a separate thread then this class will also run on this thread?
all objects which have been created in QThread::run will be in this thread.
Ok, thanks and one final question on this tread. On the worker thread I created I have a matrix which I want to transfer to a class on the main thread, is there something I have to take care of, I heard that in order to communicate a thread with the main thread I have to setup a transaction, do you know a guide or something?
anyone?
How to transfer data from a worker thread to the main thread?
you need use QMutext/QMutexLocker, QReadWriteLock, QSemaphore, and QWaitCondition.
But this way will I lock the main thread during the data transfer??
you need lock that thread which modify data and then you can send that data to another thread using signals or events.