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# 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."));
        }