Russian Qt Forum

class ImageLabel2 : public QWidget
{
    Q_OBJECT

public:
    int startHeigth;
    int startWidth;
    explicit ImageLabel2(QWidget *parent = 0);
    const QPixmap* pixmap() const;

public slots:
    void setPixmap(const QPixmap&);

protected:
    void paintEvent(QPaintEvent *);

private:
    QPixmap pix;
};

ImageLabel2::ImageLabel2(QWidget *parent) :
    QWidget(parent)
{
}

void ImageLabel2::paintEvent(QPaintEvent *event) {
    QWidget::paintEvent(event);

    if (pix.isNull())
        return;

    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing);

    QSize pixSize = pix.size();
    pixSize.scale(this->size(), Qt::KeepAspectRatio);//event->rect().size()




    QPixmap scaledPix = pix.scaled(pixSize,
                                   Qt::KeepAspectRatio,
                                   Qt::SmoothTransformation
                                   );

    painter.drawPixmap(QPoint(), scaledPix);

    qDebug() << pixSize.width() << " " << scaledPix.width() << " " << this->width();

}

const QPixmap* ImageLabel2::pixmap() const {
    return &pix;
}

void ImageLabel2::setPixmap (const QPixmap &pixmap){
    pix = pixmap;
    startHeigth = pixmap.height();
    startWidth = pixmap.width();
}

QVBoxLayout *scrollWidgetLayout = new QVBoxLayout(ui->scrollArea);


    QFrame* frame = new QFrame(ui->scrollArea);
    frame->setLayout(scrollWidgetLayout);


    ImageLabel2 *label = new ImageLabel2(ui->scrollAreaWidgetContents);
    //label->setSizePolicy(QSizePolicy::Maximum,QSizePolicy::Maximum);
    label->setPixmap(QPixmap::fromImage(QImage("1.jpg")));

    scrollWidgetLayout->addWidget(label);
    ImageLabel2 *label2 = new ImageLabel2(ui->scrollAreaWidgetContents);
    //label->setSizePolicy(QSizePolicy::Maximum,QSizePolicy::Maximum);
    label2->setPixmap(QPixmap::fromImage(QImage("1.jpg")));
    scrollWidgetLayout->addWidget(label2);

    ImageLabel2 *label3 = new ImageLabel2(ui->scrollAreaWidgetContents);
    //label->setSizePolicy(QSizePolicy::Maximum,QSizePolicy::Maximum);
    label3->setPixmap(QPixmap::fromImage(QImage("1.jpg")));
    scrollWidgetLayout->addWidget(label3);


    ui->scrollArea->setWidget(frame);

class MyDelegate : public QStyledItemDelegate  {
    public:
    MyDelegate(QObject *parent=0) : QStyledItemDelegate (parent)
    {

    }

    void paint ( QPainter * painter, const QStyleOptionViewItem & option, const QModelIndex & index ) const
    {
        if(option.state & QStyle::State_Selected){
            painter->fillRect(option.rect, option.palette.color(QPalette::Highlight));
            return;
        }
        QVariant v = index.data(Qt::UserRole);
        QImage img = v.value<QImage>();
        painter->drawImage(option.rect,img);
    }

    QSize sizeHint ( const QStyleOptionViewItem & option, const QModelIndex & index ) const
    {

        QImage img = index.data(Qt::UserRole).value<QImage>();
        int heigth = img.height();
        int width = img.width();
        return QSize(((QListWidget*)parent())->width(), ((QListWidget*)parent())->width()*heigth/width);
    }
};

QImage image1("1.jpg");
    QListWidgetItem *item1 = new QListWidgetItem();
    item1->setData(Qt::UserRole, image1);
    ui->listWidget->addItem(item1);

    QImage image2("2.jpg");
    QListWidgetItem *item2 = new QListWidgetItem();
    item2->setData(Qt::UserRole, image2);
    ui->listWidget->addItem(item2);

    QImage image3("3.jpg");
    QListWidgetItem *item3 = new QListWidgetItem();
    item3->setData(Qt::UserRole, image3);
    ui->listWidget->addItem(item3);

    QImage image4("4.jpg");
    QListWidgetItem *item4 = new QListWidgetItem();
    item4->setData(Qt::UserRole, image4);
    ui->listWidget->addItem(item4);

    ui->listWidget->setItemDelegate(new MyDelegate(ui->listWidget));

class MyQListWidget:public QListWidget
{
    void resizeEvent(QResizeEvent *e)
    {
        for(int i = 0; i < this->count(); i++)
        {
            QListWidgetItem*item = this->item(i);
            QImage img = item->data(Qt::UserRole).value<QImage>();
            item->setSizeHint(QSize(this->width(),(this->width()*img.height())/img.width()));
        }
    }
};