multithreadingqtqtconcurrent

Stop Thread started by QtConcurrent::run?


Is it possible to stop a Thread by its associated QFuture Object ? Currently i've been starting a video capturing process like this.

this->cameraThreadRepresentation = QtConcurrent::run(this,&MainWindow::startLiveCapturing);

Inside the startLiveCapturing-Method an infinite loop is running that captures images and displays them. So if the user wants to stop that process he should simply press a button and that operation stops. But it seems that i can not stop this thread by calling the cancel method like this ?

this->cameraThreadRepresentation.cancel();

What i am doing wrong and how can i stop that thread or operation.


Solution

  • From the documentation of QtConcurrent::run:

    Note that the QFuture returned by QtConcurrent::run() does not support canceling, pausing, or progress reporting. The QFuture returned can only be used to query for the running/finished status and the return value of the function.

    What you could do is have a button press set a boolean flag in your main window and build your infinite loop like this:

    _aborted = false;
    
    forever    // Qt syntax for "while( 1 )"
    {
        if( _aborted ) return;
    
        // do your actual work here
    }