1 files changed, 139 insertions, 0 deletions
diff --git a/examples/qtconcurrent/primecounter/primecounter.cpp b/examples/qtconcurrent/primecounter/primecounter.cpp
new file mode 100644
index 0000000000..01bde5d87f
--- /dev/null
+++ b/examples/qtconcurrent/primecounter/primecounter.cpp
@@ -0,0 +1,139 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include "primecounter.h"
+#include "ui_primecounter.h"
+
+PrimeCounter::PrimeCounter(QWidget *parent)
+    : QDialog(parent), stepSize(100000), ui(setupUi())
+{
+    // Control the concurrent operation with the QFutureWatcher
+    //! [1]
+    connect(ui->pushButton, &QPushButton::clicked,
+            this, [this] { start(); });
+    connect(&watcher, &QFutureWatcher<Element>::finished,
+            this, [this] { finish(); });
+    connect(&watcher, &QFutureWatcher<Element>::progressRangeChanged,
+            ui->progressBar, &QProgressBar::setRange);
+    connect(&watcher, &QFutureWatcher<Element>::progressValueChanged,
+            ui->progressBar, &QProgressBar::setValue);
+    //! [1]
+}
+
+PrimeCounter::~PrimeCounter()
+{
+    watcher.cancel();
+    delete ui;
+}
+
+//! [3]
+bool PrimeCounter::filterFunction(const Element &element)
+{
+    // Filter for primes
+    if (element <= 1)
+        return false;
+    for (Element i = 2; i*i <= element; ++i) {
+        if (element % i == 0)
+            return false;
+    }
+    return true;
+}
+//! [3]
+
+//! [4]
+void PrimeCounter::reduceFunction(Element &out, const Element &value)
+{
+    // Count the amount of primes.
+    Q_UNUSED(value);
+    ++out;
+}
+//! [4]
+
+//! [2]
+void PrimeCounter::start()
+{
+    if (ui->pushButton->isChecked()) {
+        ui->comboBox->setEnabled(false);
+        ui->pushButton->setText(tr("Cancel"));
+        ui->labelResult->setText(tr("Calculating ..."));
+        ui->labelFilter->setText(tr("Selected Reduce Option: %1").arg(ui->comboBox->currentText()));
+        fillElementList(ui->horizontalSlider->value() * stepSize);
+
+        timer.start();
+        watcher.setFuture(
+            QtConcurrent::filteredReduced(
+                &pool,
+                elementList,
+                filterFunction,
+                reduceFunction,
+                currentReduceOpt | QtConcurrent::SequentialReduce));
+//! [2]
+    } else {
+        watcher.cancel();
+        ui->progressBar->setValue(0);
+        ui->comboBox->setEnabled(true);
+        ui->labelResult->setText(tr(""));
+        ui->pushButton->setText(tr("Start"));
+        ui->labelFilter->setText(tr("Operation Canceled"));
+    }
+}
+
+void PrimeCounter::finish()
+{
+    // The finished signal from the QFutureWatcher is also emitted when cancelling.
+    if (watcher.isCanceled())
+        return;
+
+    auto elapsedTime = timer.elapsed();
+    ui->progressBar->setValue(0);
+    ui->comboBox->setEnabled(true);
+    ui->pushButton->setChecked(false);
+    ui->pushButton->setText(tr("Start"));
+    ui->labelFilter->setText(
+            tr("Filter '%1' took %2 ms to calculate").arg(ui->comboBox->currentText())
+                .arg(elapsedTime));
+    ui->labelResult->setText(
+            tr("Found %1 primes in the range of elements").arg(watcher.result()));
+}
+
+void PrimeCounter::fillElementList(unsigned int count)
+{
+    // Fill elementList with values from [1, count] when starting the calculations.
+    auto prevSize = elementList.size();
+    if (prevSize == count)
+        return; // Nothing to do here.
+
+    auto startVal = elementList.empty() ? 1 : elementList.back() + 1;
+    elementList.resize(count);
+    if (elementList.begin() + prevSize < elementList.end())
+        std::iota(elementList.begin() + prevSize, elementList.end(), startVal);
+}
+
+Ui::PrimeCounter* PrimeCounter::setupUi()
+{
+    Ui::PrimeCounter *setupUI = new Ui::PrimeCounter;
+    setupUI->setupUi(this);
+    setModal(true);
+
+    // Set up the slider
+    connect(setupUI->horizontalSlider, &QSlider::valueChanged,
+            this, [setupUI, this] (const int &pos) {
+        setupUI->labelResult->setText("");
+        setupUI->labelSize->setText(tr("Elements in list: %1").arg(pos * stepSize));
+    });
+    setupUI->horizontalSlider->setValue(30);
+
+    // Set up the combo box
+    setupUI->comboBox->insertItem(0, tr("Unordered Reduce"), QtConcurrent::UnorderedReduce);
+    setupUI->comboBox->insertItem(1, tr("Ordered Reduce"), QtConcurrent::OrderedReduce);
+
+    auto comboBoxChange = [this, setupUI](int pos) {
+        currentReduceOpt = setupUI->comboBox->itemData(pos).value<QtConcurrent::ReduceOptions>();
+        setupUI->labelFilter->setText(tr("Selected Reduce Option: %1")
+                                          .arg(setupUI->comboBox->currentText()));
+    };
+    comboBoxChange(setupUI->comboBox->currentIndex());
+    connect(setupUI->comboBox, &QComboBox::currentIndexChanged, this, comboBoxChange);
+
+    return setupUI;
+}