Using QThread and QTimer to run a methode

Question

hi i have class with function that run according to QTimer (run every 30ms for example )

class testclass
{
    public slots:
    void   DoSomthing();

}

testclass::testclass()
{
    QTimer *timer = new QTimer();
    connect(timer , SIGNAL(timeout()) , this , SLOT(DoSomthing());
    timer->start(30);

}

but i want my DoSomthing() function to run in separate thread , that's mean make DoSomthing() function in separate thread and control the function using timer (run my function in thread every some time).

class testclass
{
    public slots:
        void DoSomthing();
}

testclass::testclass()
{
    QThread thread = new QThread ();
    connect(thread , SIGNAL(started()) , this , SLOT(DoSomthing());

    QTimer *timer = new QTimer();
    connect(???, SIGNAL(?????) , ????, SLOT(?????); // how i can continue this code 
    timer->start(30);
}

how i can do it ?

score 4 · Answer 1 · answered Jul 23 '13 at 22:32

4

I recommend to use QtConcurrent. It is a lot of less headache then using directly QThread.

#include <QtConcurrent/QtConcurrent>

void SomeClass::timerSlot() {
    QtConcurrent::run(this, &SomeClass::SomePrivateMethodToRunInThread);
}

void SomeClass::SomePrivateMethodToRunInThread() {
    doSomething();
    emit someSlot();
}

emitting a signal is thread safe if you are passing only a by values (or const reference) and connecting it using Qt::AutoConnection (default value) or Qt::QueuedConnection.

answered Jul 23 '13 at 22:32

Marek R

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can you explain what is timerSlot – user2612344 Jul 23 '13 at 22:34
some slot which you are connecting to a timer – Marek R Jul 23 '13 at 22:36

4pie0 · Accepted Answer · 2013-07-23T22:38:41.893

0

class TestClass : public QObject
{
    Q_OBJECT

  public Q_SLOTS:
      void doSomething();
};


int main(int argv, char** args)
{
  QApplication app(argv, args);

  QTimer *timer = new QTimer();

  // Thread
  TestClass test;
  QThread t;
  test.moveToThread(&t);
  t.start();

  // Connections
  QObject::connect(timer, SIGNAL(timeout()), &test, SLOT(doSomething()));

  return app.exec();
}

regarding comments, you can also subclass QThread directly this way:

class MyThreadedClass : public QThread
{
  MyThreadClass(){}

  void doSomething(){
      }

  void run()
  {
    doSomething();
  }
};

int main()
{
  MyThreadClass thread();
  thread.start(); // MyThreadClass is now running

  return 0;
}

edited Jul 23 '13 at 22:38

answered Jul 23 '13 at 22:15

4pie0

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9
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thanks for reply , but there is no slot function in your class , and is it possible to run just the a function in a separate thread ? – user2612344 Jul 23 '13 at 22:19
what you mean by "just put a function" ? to run a single function in another thread? – 4pie0 Jul 23 '13 at 22:27
I mean run only the function not all the class – user2612344 Jul 23 '13 at 22:29
do you need qthread then? maybe just common POSIX thread or your platform equivalent – 4pie0 Jul 23 '13 at 22:30

Using QThread and QTimer to run a methode

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