main.cpp 范例文件

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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 connect 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(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QString text("Qt Concurrent is not yet supported on this platform");
    QLabel *label = new QLabel(text);
    label->setWordWrap(true);
#if defined(Q_WS_S60) || defined(Q_WS_MAEMO_5)
    label->showMaximized();
#else
    label->show();
#endif
    qDebug() << text;
    app.exec();
}
#endif