mainwindow.cpp Example File
^{itemviews/pixelator/mainwindow.cpp}

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    #include <QtGui>

    #include "imagemodel.h"
    #include "mainwindow.h"
    #include "pixeldelegate.h"

    MainWindow::MainWindow()
    {
        currentPath = QDir::home().absolutePath();
        model = 0;

        view = new QTableView;
        view->setItemDelegate(new PixelDelegate(this));
        view->setShowGrid(false);
        view->horizontalHeader()->hide();
        view->verticalHeader()->hide();
        setCentralWidget(view);

        QMenu *fileMenu = new QMenu(tr("&File"), this);
        QAction *openAction = fileMenu->addAction(tr("&Open..."));
        openAction->setShortcut(QKeySequence(tr("Ctrl+O")));

        printAction = fileMenu->addAction(tr("&Print..."));
        printAction->setEnabled(false);
        printAction->setShortcut(QKeySequence(tr("Ctrl+P")));

        QAction *quitAction = fileMenu->addAction(tr("E&xit"));
        quitAction->setShortcut(QKeySequence(tr("Ctrl+Q")));

        QMenu *helpMenu = new QMenu(tr("&Help"), this);
        QAction *aboutAction = helpMenu->addAction(tr("&About"));

        menuBar()->addMenu(fileMenu);
        menuBar()->addSeparator();
        menuBar()->addMenu(helpMenu);

        connect(openAction, SIGNAL(triggered()), this, SLOT(chooseImage()));
        connect(printAction, SIGNAL(triggered()), this, SLOT(printImage()));
        connect(quitAction, SIGNAL(triggered()), qApp, SLOT(quit()));
        connect(aboutAction, SIGNAL(triggered()), this, SLOT(showAboutBox()));

        setWindowTitle(tr("Pixelator"));
        resize(640, 480);
    }

    void MainWindow::chooseImage()
    {
        QString fileName = QFileDialog::getOpenFileName(this,
            tr("Choose an image"), currentPath, "*");

        if (!fileName.isEmpty()) {
            if (openImage(fileName))
                currentPath = fileName;
        }
    }

    bool MainWindow::openImage(const QString &fileName)
    {
        QImage image;

        if (image.load(fileName)) {
            ImageModel *newModel = new ImageModel(image);
            view->setModel(newModel);
            delete model;
            model = newModel;
            setWindowTitle(tr("%1 - %2").arg(fileName).arg(tr("Pixelator")));

            printAction->setEnabled(true);

            int rows = model->rowCount(QModelIndex());
            int columns = model->columnCount(QModelIndex());
            for (int row = 0; row < rows; ++row)
                view->resizeRowToContents(row);
            for (int column = 0; column < columns; ++column)
                view->resizeColumnToContents(column);

            return true;
        }
        return false;
    }

    void MainWindow::printImage()
    {
        if (model->rowCount(QModelIndex())*model->columnCount(QModelIndex())
            > 90000) {
            int answer = QMessageBox::question(this, tr("Large Image Size"),
                tr("The printed image may be very large. Are you sure that "
                   "you want to print it?"),
                QMessageBox::Yes, QMessageBox::No);
            if (answer == QMessageBox::No)
                return;
        }

        QPrinter printer(QPrinter::HighResolution);

        QPrintDialog *dlg = new QPrintDialog(&printer, this);
        dlg->setWindowTitle(tr("Print Image"));

        if (dlg->exec() != QDialog::Accepted)
            return;

        QPainter painter;
        painter.begin(&printer);

        int rows = model->rowCount(QModelIndex());
        int columns = model->columnCount(QModelIndex());
        int sourceWidth = (columns+1) * ItemSize;
        int sourceHeight = (rows+1) * ItemSize;

        painter.save();

        double xscale = printer.pageRect().width()/double(sourceWidth);
        double yscale = printer.pageRect().height()/double(sourceHeight);
        double scale = qMin(xscale, yscale);

        painter.translate(printer.paperRect().x() + printer.pageRect().width()/2,
                          printer.paperRect().y() + printer.pageRect().height()/2);
        painter.scale(scale, scale);
        painter.translate(-sourceWidth/2, -sourceHeight/2);

        QStyleOptionViewItem option;
        QModelIndex parent = QModelIndex();

        QProgressDialog progress(tr("Printing..."), tr("Cancel"), 0, rows, this);
        float y = ItemSize/2;

        for (int row = 0; row < rows; ++row) {
            progress.setValue(row);
            qApp->processEvents();
            if (progress.wasCanceled())
                break;

            float x = ItemSize/2;

            for (int column = 0; column < columns; ++column) {
                option.rect = QRect(int(x), int(y), ItemSize, ItemSize);
                view->itemDelegate()->paint(&painter, option,
                                            model->index(row, column, parent));
                x = x + ItemSize;
            }
            y = y + ItemSize;
        }
        progress.setValue(rows);

        painter.restore();
        painter.end();

        if (progress.wasCanceled()) {
            QMessageBox::information(this, tr("Printing canceled"),
                tr("The printing process was canceled."), QMessageBox::Cancel);
        }
    }

    void MainWindow::showAboutBox()
    {
        QMessageBox::about(this, tr("About the Pixelator example"),
            tr("This example demonstrates how a standard view and a custom\n"
               "delegate can be used to produce a specialized representation\n "
               "of data in a simple custom model."));
    }