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#include <QtGui>

#include "imageviewer.h"

//! [0]

ImageViewer::ImageViewer()

{

    imageLabel = new QLabel;

    imageLabel->setBackgroundRole(QPalette::Base);

    imageLabel->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored);

    imageLabel->setScaledContents(true);

    scrollArea = new QScrollArea;

    scrollArea->setBackgroundRole(QPalette::Dark);

    scrollArea->setWidget(imageLabel);

    setCentralWidget(scrollArea);

    createActions();

    createMenus();

    setWindowTitle(tr("Image Viewer"));

    resize(500, 400);

}

//! [0]

//! [1]

void ImageViewer::open()

//! [1] //! [2]

{

    QString fileName = QFileDialog::getOpenFileName(this,

                                    tr("Open File"), QDir::currentPath());

    if (!fileName.isEmpty()) {

        QImage image(fileName);

        if (image.isNull()) {

            QMessageBox::information(this, tr("Image Viewer"),

                                     tr("Cannot load %1.").arg(fileName));

            return;

        }

//! [2] //! [3]

        imageLabel->setPixmap(QPixmap::fromImage(image));

//! [3] //! [4]

        scaleFactor = 1.0;

        printAct->setEnabled(true);

        fitToWindowAct->setEnabled(true);

        updateActions();

        if (!fitToWindowAct->isChecked())

            imageLabel->adjustSize();

    }

}

//! [4]

//! [5]

void ImageViewer::print()

//! [5] //! [6]

{

    Q_ASSERT(imageLabel->pixmap());

#ifndef QT_NO_PRINTER

//! [6] //! [7]

    QPrintDialog dialog(&printer, this);

//! [7] //! [8]

    if (dialog.exec()) {

        QPainter painter(&printer);

        QRect rect = painter.viewport();

        QSize size = imageLabel->pixmap()->size();

        size.scale(rect.size(), Qt::KeepAspectRatio);

        painter.setViewport(rect.x(), rect.y(), size.width(), size.height());

        painter.setWindow(imageLabel->pixmap()->rect());

        painter.drawPixmap(0, 0, *imageLabel->pixmap());

    }

#endif

}

//! [8]

//! [9]

void ImageViewer::zoomIn()

//! [9] //! [10]

{

    scaleImage(1.25);

}

void ImageViewer::zoomOut()

{

    scaleImage(0.8);

}

//! [10] //! [11]

void ImageViewer::normalSize()

//! [11] //! [12]

{

    imageLabel->adjustSize();

    scaleFactor = 1.0;

}

//! [12]

//! [13]

void ImageViewer::fitToWindow()

//! [13] //! [14]

{

    bool fitToWindow = fitToWindowAct->isChecked();

    scrollArea->setWidgetResizable(fitToWindow);

    if (!fitToWindow) {

        normalSize();

    }

    updateActions();

}

//! [14]

//! [15]

void ImageViewer::about()

//! [15] //! [16]

{

    QMessageBox::about(this, tr("About Image Viewer"),

            tr("<p>The <b>Image Viewer</b> example shows how to combine QLabel "

               "and QScrollArea to display an image. QLabel is typically used "

               "for displaying a text, but it can also display an image. "

               "QScrollArea provides a scrolling view around another widget. "

               "If the child widget exceeds the size of the frame, QScrollArea "

               "automatically provides scroll bars. </p><p>The example "

               "demonstrates how QLabel's ability to scale its contents "

               "(QLabel::scaledContents), and QScrollArea's ability to "

               "automatically resize its contents "

               "(QScrollArea::widgetResizable), can be used to implement "

               "zooming and scaling features. </p><p>In addition the example "

               "shows how to use QPainter to print an image.</p>"));

}

//! [16]

//! [17]

void ImageViewer::createActions()

//! [17] //! [18]

{

    openAct = new QAction(tr("&Open..."), this);

    openAct->setShortcut(tr("Ctrl+O"));

    connect(openAct, SIGNAL(triggered()), this, SLOT(open()));

    printAct = new QAction(tr("&Print..."), this);

    printAct->setShortcut(tr("Ctrl+P"));

    printAct->setEnabled(false);

    connect(printAct, SIGNAL(triggered()), this, SLOT(print()));

    exitAct = new QAction(tr("E&xit"), this);

    exitAct->setShortcut(tr("Ctrl+Q"));

    connect(exitAct, SIGNAL(triggered()), this, SLOT(close()));

    zoomInAct = new QAction(tr("Zoom &In (25%)"), this);

    zoomInAct->setShortcut(tr("Ctrl++"));

    zoomInAct->setEnabled(false);

    connect(zoomInAct, SIGNAL(triggered()), this, SLOT(zoomIn()));

    zoomOutAct = new QAction(tr("Zoom &Out (25%)"), this);

    zoomOutAct->setShortcut(tr("Ctrl+-"));

    zoomOutAct->setEnabled(false);

    connect(zoomOutAct, SIGNAL(triggered()), this, SLOT(zoomOut()));

    normalSizeAct = new QAction(tr("&Normal Size"), this);

    normalSizeAct->setShortcut(tr("Ctrl+S"));

    normalSizeAct->setEnabled(false);

    connect(normalSizeAct, SIGNAL(triggered()), this, SLOT(normalSize()));

    fitToWindowAct = new QAction(tr("&Fit to Window"), this);

    fitToWindowAct->setEnabled(false);

    fitToWindowAct->setCheckable(true);

    fitToWindowAct->setShortcut(tr("Ctrl+F"));

    connect(fitToWindowAct, SIGNAL(triggered()), this, SLOT(fitToWindow()));

    aboutAct = new QAction(tr("&About"), this);

    connect(aboutAct, SIGNAL(triggered()), this, SLOT(about()));

    aboutQtAct = new QAction(tr("About &Qt"), this);

    connect(aboutQtAct, SIGNAL(triggered()), qApp, SLOT(aboutQt()));

}

//! [18]

//! [19]

void ImageViewer::createMenus()

//! [19] //! [20]

{

    fileMenu = new QMenu(tr("&File"), this);

    fileMenu->addAction(openAct);

    fileMenu->addAction(printAct);

    fileMenu->addSeparator();

    fileMenu->addAction(exitAct);

    viewMenu = new QMenu(tr("&View"), this);

    viewMenu->addAction(zoomInAct);

    viewMenu->addAction(zoomOutAct);

    viewMenu->addAction(normalSizeAct);

    viewMenu->addSeparator();

    viewMenu->addAction(fitToWindowAct);

    helpMenu = new QMenu(tr("&Help"), this);

    helpMenu->addAction(aboutAct);

    helpMenu->addAction(aboutQtAct);

    menuBar()->addMenu(fileMenu);

    menuBar()->addMenu(viewMenu);

    menuBar()->addMenu(helpMenu);

}

//! [20]

//! [21]

void ImageViewer::updateActions()

//! [21] //! [22]

{

    zoomInAct->setEnabled(!fitToWindowAct->isChecked());

    zoomOutAct->setEnabled(!fitToWindowAct->isChecked());

    normalSizeAct->setEnabled(!fitToWindowAct->isChecked());

}

//! [22]

//! [23]

void ImageViewer::scaleImage(double factor)

//! [23] //! [24]

{

    Q_ASSERT(imageLabel->pixmap());

    scaleFactor *= factor;

    imageLabel->resize(scaleFactor * imageLabel->pixmap()->size());

    adjustScrollBar(scrollArea->horizontalScrollBar(), factor);

    adjustScrollBar(scrollArea->verticalScrollBar(), factor);

    zoomInAct->setEnabled(scaleFactor < 3.0);

    zoomOutAct->setEnabled(scaleFactor > 0.333);

}

//! [24]

//! [25]

void ImageViewer::adjustScrollBar(QScrollBar *scrollBar, double factor)

//! [25] //! [26]

{

    scrollBar->setValue(int(factor * scrollBar->value()

                            + ((factor - 1) * scrollBar->pageStep()/2)));

}

//! [26]