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#include <QtGui>

class MyScrollArea : public QAbstractScrollArea

{

public:

    MyScrollArea(QWidget *w);

    void setWidget(QWidget *w);

protected:

    void scrollContentsBy(int dx, int dy);

    void resizeEvent(QResizeEvent *event);

private:

    void updateWidgetPosition();

    void updateArea();

    QWidget *widget;

};

MyScrollArea::MyScrollArea(QWidget *widget)

    : QAbstractScrollArea()

{

    setWidget(widget);

}

void MyScrollArea::setWidget(QWidget *w)

{

    widget = w;

    widget->setParent(viewport());

    if (!widget->testAttribute(Qt::WA_Resized))

        widget->resize(widget->sizeHint());

    verticalScrollBar()->setValue(0);

    verticalScrollBar()->setValue(0);

    updateArea();

}

void MyScrollArea::updateWidgetPosition()

{

//! [0]

    int hvalue = horizontalScrollBar()->value();

    int vvalue = verticalScrollBar()->value();

    QPoint topLeft = viewport()->rect().topLeft();

    widget->move(topLeft.x() - hvalue, topLeft.y() - vvalue);

//! [0]

}

void MyScrollArea::scrollContentsBy(int /*dx*/, int /*dy*/)

{

    updateWidgetPosition();

}

void MyScrollArea::updateArea()

{

//! [1]

    QSize areaSize = viewport()->size();

    QSize  widgetSize = widget->size();

    verticalScrollBar()->setPageStep(widgetSize.height());

    horizontalScrollBar()->setPageStep(widgetSize.width());

    verticalScrollBar()->setRange(0, widgetSize.height() - areaSize.height());

    horizontalScrollBar()->setRange(0, widgetSize.width() - areaSize.width());

    updateWidgetPosition();

//! [1]

}

void MyScrollArea::resizeEvent(QResizeEvent *event)

{

    updateArea();

}

int main(int argv, char **args)

{

    QApplication app(argv, args);

    QPixmap pixmap("mypixmap.png");

    QLabel label;

    label.setPixmap(pixmap);

    MyScrollArea area(&label);

    area.resize(300, 300);

    area.show();

    area.setWidget(&label);

    return app.exec();

}