QT) ThreadScaler

imagescaling.h

#ifndef IMAGESCALING_H

#define IMAGESCALING_H

#include <QtWidgets>

#include <QtConcurrent>

class Images : public QWidget

{

Q_OBJECT

public:

    Images(QWidget *parent = 0);

    ~Images();

public Q_SLOTS:

    void open();

    void showImage(int num);

    void finished();

private:

    QPushButton *openButton;

    QPushButton *cancelButton;

    QPushButton *pauseButton;

    QVBoxLayout *mainLayout;

    QList<QLabel *> labels;

    QGridLayout *imagesLayout;

    QFutureWatcher<QImage> *imageScaling;

};

#endif // IMAGESCALING_H

imagescaling.cpp

#include "imagescaling.h"

#include "math.h"

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 QStandardPaths::PicturesLocation.

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

                            QStandardPaths::writableLocation(QStandardPaths::PicturesLocation),

                            "*.jpg *.png");

    if (files.count() == 0)

        return;

    // Do a simple layout.

    qDeleteAll(labels);

    labels.clear();

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

    //int dim = 4;

    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));               //이부분만 바꾸면 파일에 대해서 행해지는 옵션을 바꿀수 있따.

    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);

}

main.cpp

#include <QtWidgets>

#include <QtConcurrent>

#include "imagescaling.h"

int main(int argc, char *argv[])

{

    QApplication app(argc,argv);

    Images imageView;

    imageView.show();

    return app.exec();

}

threadScaler.cpp

#include "imagescaling.h"

#include "math.h"

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 QStandardPaths::PicturesLocation.

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

                            QStandardPaths::writableLocation(QStandardPaths::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);

}

threadScaler.h

#ifndef IMAGESCALING_H

#define IMAGESCALING_H

#include <QtWidgets>

#include <QtConcurrent>

class Images : public QWidget

{

Q_OBJECT

public:

    Images(QWidget *parent = 0);

    ~Images();

public Q_SLOTS:

    void open();

    void showImage(int num);

    void finished();

private:

    QPushButton *openButton;

    QPushButton *cancelButton;

    QPushButton *pauseButton;

    QVBoxLayout *mainLayout;

    QList<QLabel *> labels;

    QGridLayout *imagesLayout;

    QFutureWatcher<QImage> *imageScaling;

};

#endif // IMAGESCALING_H