how to select an image in a scroll area?

[milad-sh]

I have written the code below in order to load images in a scroll area. now on I want to select an image an apply zoom in and zoom out actions on the selected image. how can I do that?
mainwindow.cpp

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    layout = ui->verticalLayout_5;
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_actionOpen_triggered()
{


    QString directory = QFileDialog::getExistingDirectory(this,
                                                          tr("Open Directory"),
                                                          QDir::homePath(),
                                                          QFileDialog::ShowDirsOnly| QFileDialog::DontResolveSymlinks);
    int nrows = 1;
    int ncols = 1;
    HorizontalScrollArea *scroll = new HorizontalScrollArea(nrows, ncols);
    layout->addWidget(scroll);
    QDir dir(directory);
    dir.setNameFilters({"*.png", "*.jpg"});
    for(const QFileInfo & finfo: dir.entryInfoList()){
        int column = scroll->columnCount();
        for(int row=0; row < nrows; row++){
            QPixmap pic(finfo.absoluteFilePath());
            QImage image(finfo.absoluteFilePath());
            QLabel *label = new QLabel();
            label->setFrameShape(QFrame::WinPanel);
            label->setFrameShadow(QFrame::Raised);
            label->setAlignment(Qt::AlignCenter);

            label->setPixmap(pic.scaled(600,500,Qt::KeepAspectRatio));
            scroll->addWidget(label, row, column);
        }
    }
}

horizontalscrollarea.h

class HorizontalScrollArea : public QScrollArea
{
    QWidget *contentWidget;
    QGridLayout *grid;
    int nRows;
    int nColumns;
public:
    HorizontalScrollArea(int rows, int cols, QWidget *parent = Q_NULLPTR)
        :QScrollArea(parent), nRows(rows), nColumns(cols)
    {
        setWidgetResizable(true);
        contentWidget = new QWidget(this);
        setWidget(contentWidget);
        grid = new QGridLayout(contentWidget);
        setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    }

    void addWidget(QWidget *w, int row, int col){
        grid->addWidget(w, row, col);
        adaptSize();
    }

    int columnCount() const{
        if(grid->count() == 0){
            return 0;
        }
        return grid->columnCount();
    }

private:
    void adaptSize(){
        if(columnCount() >= nColumns ){
            int w = 1.0*(width() - grid->horizontalSpacing()*(nColumns+1.6))/nColumns;
            int wCorrected = w*columnCount() + grid->horizontalSpacing()*(columnCount()+2);
            contentWidget->setFixedWidth(wCorrected);
        }
        contentWidget->setFixedHeight(viewport()->height());
    }
protected:
    void resizeEvent(QResizeEvent *event){
        QScrollArea::resizeEvent(event);
        adaptSize();
    }
};

[mrjj]

Hi and welcome to the forums
You could use something like
https://wiki.qt.io/Clickable_QLabel
to make it able to detect mousePress.

• zoom in and zoom out actions ?
  You mean zooming as in image size shown or
  as in hovering effect when mouse is over the image or leaving it ?
  I assume hover and for that you need to implement
  enterEvent and leaveEvent
  Like shown here
  https://stackoverflow.com/questions/40729040/how-to-create-qt-label-hover-effect

It just set text color so you need to tell what type of effect you had in mind ?
One option is to also override paintEvent and paint the effect using QPainter.
for more advanced stuff, there is also
http://doc.qt.io/qt-5/qgraphicseffect.html#details