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#include "imagescaling.h"

#include "math.h"

#ifndef QT_NO_CONCURRENT

const int imageSize = 100;

QImage scale(const QString &imageFileName)

{

    QImage image(imageFileName);

    return image.scaled(QSize(imageSize, imageSize), Qt::IgnoreAspectRatio, Qt::SmoothTransformation);

}

Images::Images(QWidget *parent) 

: QWidget(parent)

{

    setWindowTitle(tr("Image loading and scaling example"));

    resize(800, 600);

    imageScaling = new QFutureWatcher<QImage>(this);

    connect(imageScaling, SIGNAL(resultReadyAt(int)), SLOT(showImage(int)));

    connect(imageScaling, SIGNAL(finished()), SLOT(finished()));

    openButton = new QPushButton(tr("Open Images"));

    connect(openButton, SIGNAL(clicked()), SLOT(open()));

    cancelButton = new QPushButton(tr("Cancel"));

    cancelButton->setEnabled(false);

    connect(cancelButton, SIGNAL(clicked()), imageScaling, SLOT(cancel()));

    pauseButton = new QPushButton(tr("Pause/Resume"));

    pauseButton->setEnabled(false);

    connect(pauseButton, SIGNAL(clicked()), imageScaling, SLOT(togglePaused()));

    QHBoxLayout *buttonLayout = new QHBoxLayout();

    buttonLayout->addWidget(openButton);

    buttonLayout->addWidget(cancelButton);

    buttonLayout->addWidget(pauseButton);

    buttonLayout->addStretch();

    imagesLayout = new QGridLayout();

    mainLayout = new QVBoxLayout();

    mainLayout->addLayout(buttonLayout);

    mainLayout->addLayout(imagesLayout);

    mainLayout->addStretch();

    setLayout(mainLayout);

}

Images::~Images()

{

    imageScaling->cancel();

    imageScaling->waitForFinished();

}

void Images::open()

{

    // Cancel and wait if we are already loading images.

    if (imageScaling->isRunning()) {

        imageScaling->cancel();

        imageScaling->waitForFinished();

    }

    // Show a file open dialog at QDesktopServices::PicturesLocation.

    QStringList files = QFileDialog::getOpenFileNames(this, tr("Select Images"), 

                            QDesktopServices::storageLocation(QDesktopServices::PicturesLocation),

                            "*.jpg *.png");

    if (files.count() == 0)

        return;

    // Do a simple layout.

    qDeleteAll(labels);

    labels.clear();

    int dim = sqrt(qreal(files.count())) + 1;

    for (int i = 0; i < dim; ++i) {

        for (int j = 0; j < dim; ++j) {

            QLabel *imageLabel = new QLabel;

            imageLabel->setFixedSize(imageSize,imageSize);

            imagesLayout->addWidget(imageLabel,i,j);

            labels.append(imageLabel);

        }

    }

    // Use mapped to run the thread safe scale function on the files.

    imageScaling->setFuture(QtConcurrent::mapped(files, scale));

    openButton->setEnabled(false);

    cancelButton->setEnabled(true);

    pauseButton->setEnabled(true);

}

void Images::showImage(int num)

{

    labels[num]->setPixmap(QPixmap::fromImage(imageScaling->resultAt(num)));

}

void Images::finished()

{

    openButton->setEnabled(true);

    cancelButton->setEnabled(false);

    pauseButton->setEnabled(false);

}

#endif // QT_NO_CONCURRENT