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class ImageViewDialog : public QDialog
{
	Q_OBJECT
	
// Member Variables
private:
	double scaleFactor;
	QLabel* imageLabel;
	QScrollArea* scrollArea;
	QPushButton* buttonZoomIn;
	QPushButton* buttonZoomOut;
	
// Constructor & Destructor
public:
	ImageViewDialog(const QString& image, QWidget* parent=0);
	
// Member Functions
private:
	void scaleImage(double factor);
	void adjustScrollBar(QScrollBar* scrollBar, double factor);
private slots:
	void slotZoomIn();
	void slotNormalSize();
	void slotZoomOut();
};

ImageViewDialog::ImageViewDialog(const QString& fileName, QWidget* parent) : QDialog(parent)
{
	setWindowFlags(windowFlags()|Qt::WindowMaximizeButtonHint);
	QImage image(fileName);
	if(image.isNull()){
		QMessageBox::information(this, tr("Show image"), tr("Cannot load %1.").arg(fileName));
	}
	
	imageLabel=new QLabel;
	imageLabel->setBackgroundRole(QPalette::Base);
	imageLabel->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored);
	imageLabel->setScaledContents(true);
	imageLabel->setPixmap(QPixmap::fromImage(image));
	scaleFactor=1.0;
	
	scrollArea=new QScrollArea;
	scrollArea->setBackgroundRole(QPalette::Dark);
	scrollArea->setWidget(imageLabel);
	
	buttonZoomIn=new QPushButton(tr("Zoom &In"));
	QPushButton* buttonNormalSize=new QPushButton(tr("&Normal Size"));
	buttonZoomOut=new QPushButton(tr("Zoom &Out"));
	QPushButton* buttonClose=new QPushButton(tr("&Close"));
	connect(buttonZoomIn, SIGNAL(clicked()), SLOT(slotZoomIn()));
	connect(buttonNormalSize, SIGNAL(clicked()), SLOT(slotNormalSize()));
	connect(buttonZoomOut, SIGNAL(clicked()), SLOT(slotZoomOut()));
	connect(buttonClose, SIGNAL(clicked()), SLOT(accept()));
	QHBoxLayout* buttonLayout=new QHBoxLayout;
	buttonLayout->setMargin(5);
	buttonLayout->addStretch(1);
	buttonLayout->addWidget(buttonZoomIn);
	buttonLayout->addWidget(buttonNormalSize);
	buttonLayout->addWidget(buttonZoomOut);
	buttonLayout->addStretch(1);
	buttonLayout->addWidget(buttonClose);
	
	QVBoxLayout* layout=new QVBoxLayout;
	layout->setSpacing(5); layout->setMargin(5);
	layout->addWidget(scrollArea);
	layout->addLayout(buttonLayout);
	setLayout(layout);
}

void ImageViewDialog::scaleImage(double factor)
{
	scaleFactor*=factor;
	imageLabel->resize(scaleFactor * imageLabel->pixmap()->size());
	
	adjustScrollBar(scrollArea->horizontalScrollBar(), factor);
	adjustScrollBar(scrollArea->verticalScrollBar(), factor);
	
	buttonZoomIn->setEnabled(scaleFactor < 3.0);
	buttonZoomOut->setEnabled(scaleFactor > 0.333);
}

void ImageViewDialog::adjustScrollBar(QScrollBar* scrollBar, double factor)
{
	scrollBar->setValue(int(factor * scrollBar->value() + ((factor - 1) * scrollBar->pageStep()/2)));
}

void ImageViewDialog::slotZoomIn()
{
	scaleImage(1.25);
}

void ImageViewDialog::slotNormalSize()
{
	imageLabel->adjustSize();
	scaleFactor=1.0;
	buttonZoomIn->setEnabled(true);
	buttonZoomOut->setEnabled(true);
}

void ImageViewDialog::slotZoomOut()
{
	scaleImage(0.8);
}

scrollArea->resize(imageLabel->size());

	QSize size=imageLabel->size();
	size.rheight()+=2*QApplication::style()->pixelMetric(QStyle::PM_DefaultFrameWidth);
	size.rwidth()+=2*QApplication::style()->pixelMetric(QStyle::PM_DefaultFrameWidth);
	scrollArea->setMinimumSize(size);