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#include <QtGui>

#ifndef QT_NO_CONCURRENT

using namespace QtConcurrent;

const int iterations = 20;

void spin(int &iteration)

{

    const int work = 1000 * 1000 * 40;

    volatile int v = 0;

    for (int j = 0; j < work; ++j)

        ++v;

    qDebug() << "iteration" << iteration << "in thread" << QThread::currentThreadId();

}

int main(int argc, char **argv)

{

    QApplication app(argc, argv);

    // Prepare the vector.

    QVector<int> vector;

    for (int i = 0; i < iterations; ++i)

        vector.append(i);

    // Create a progress dialog.

    QProgressDialog dialog;

    dialog.setLabelText(QString("Progressing using %1 thread(s)...").arg(QThread::idealThreadCount()));

    // Create a QFutureWatcher and conncect signals and slots.

    QFutureWatcher<void> futureWatcher;

    QObject::connect(&futureWatcher, SIGNAL(finished()), &dialog, SLOT(reset()));

    QObject::connect(&dialog, SIGNAL(canceled()), &futureWatcher, SLOT(cancel()));

    QObject::connect(&futureWatcher, SIGNAL(progressRangeChanged(int, int)), &dialog, SLOT(setRange(int, int)));

    QObject::connect(&futureWatcher, SIGNAL(progressValueChanged(int)), &dialog, SLOT(setValue(int)));

    // Start the computation.

    futureWatcher.setFuture(QtConcurrent::map(vector, spin));

    // Display the dialog and start the event loop.

    dialog.exec();

    futureWatcher.waitForFinished();

    // Query the future to check if was canceled.

    qDebug() << "Canceled?" << futureWatcher.future().isCanceled();

}

#else

int main()

{

	qDebug() << "Qt Concurrent is not yet supported on this platform";

}

#endif