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| |
| #include <QtWidgets> |
| #include <QtConcurrent> |
| |
| #include <functional> |
| |
| using namespace QtConcurrent; |
| |
| int main(int argc, char **argv) |
| { |
| QApplication app(argc, argv); |
| |
| const int iterations = 20; |
| |
| // 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, &QFutureWatcher<void>::finished, &dialog, &QProgressDialog::reset); |
| QObject::connect(&dialog, &QProgressDialog::canceled, &futureWatcher, &QFutureWatcher<void>::cancel); |
| QObject::connect(&futureWatcher, &QFutureWatcher<void>::progressRangeChanged, &dialog, &QProgressDialog::setRange); |
| QObject::connect(&futureWatcher, &QFutureWatcher<void>::progressValueChanged, &dialog, &QProgressDialog::setValue); |
| |
| // Our function to compute |
| std::function<void(int&)> 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(); |
| }; |
| |
| // 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(); |
| } |