qtbase-opensource-src/examples/qtconcurrent/map/main.cpp

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#include <QImage>
#include <QList>
#include <QThread>
#include <QDebug>
#include <QGuiApplication>
#include <qtconcurrentmap.h>
#include <functional>
int main(int argc, char *argv[])
{
QGuiApplication app(argc, argv);
const int imageCount = 20;
// Create a list containing imageCount images.
QList<QImage> images;
for (int i = 0; i < imageCount; ++i)
images.append(QImage(1600, 1200, QImage::Format_ARGB32_Premultiplied));
std::function<QImage(const QImage&)> scale = [](const QImage &image) -> QImage
{
qDebug() << "Scaling image in thread" << QThread::currentThread();
return image.scaled(QSize(100, 100), Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
};
// Use QtConcurrentBlocking::mapped to apply the scale function to all the
// images in the list.
QList<QImage> thumbnails = QtConcurrent::blockingMapped(images, scale);
return 0;
}