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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::homePath();
         model = new ImageModel(this);

         QWidget *centralWidget = new QWidget;

         view = new QTableView;
         view->setShowGrid(false);
         view->horizontalHeader()->hide();
         view->verticalHeader()->hide();
         view->horizontalHeader()->setMinimumSectionSize(1);
         view->verticalHeader()->setMinimumSectionSize(1);
         view->setModel(model);

         PixelDelegate *delegate = new PixelDelegate(this);
         view->setItemDelegate(delegate);

         QLabel *pixelSizeLabel = new QLabel(tr("Pixel size:"));
         QSpinBox *pixelSizeSpinBox = new QSpinBox;
         pixelSizeSpinBox->setMinimum(4);
         pixelSizeSpinBox->setMaximum(32);
         pixelSizeSpinBox->setValue(12);

         QMenu *fileMenu = new QMenu(tr("&File"), this);
         QAction *openAction = fileMenu->addAction(tr("&Open..."));
         openAction->setShortcuts(QKeySequence::Open);

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

         QAction *quitAction = fileMenu->addAction(tr("E&xit"));
         quitAction->setShortcuts(QKeySequence::Quit);

         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()));
         connect(pixelSizeSpinBox, SIGNAL(valueChanged(int)),
                 delegate, SLOT(setPixelSize(int)));
         connect(pixelSizeSpinBox, SIGNAL(valueChanged(int)),
                 this, SLOT(updateView()));

         QHBoxLayout *controlsLayout = new QHBoxLayout;
         controlsLayout->addWidget(pixelSizeLabel);
         controlsLayout->addWidget(pixelSizeSpinBox);
         controlsLayout->addStretch(1);

         QVBoxLayout *mainLayout = new QVBoxLayout;
         mainLayout->addWidget(view);
         mainLayout->addLayout(controlsLayout);
         centralWidget->setLayout(mainLayout);

         setCentralWidget(centralWidget);

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

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

         if (!fileName.isEmpty())
             openImage(fileName);
     }

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

         if (image.load(fileName)) {
             model->setImage(image);
             if (!fileName.startsWith(":/")) {
                 currentPath = fileName;
                 setWindowTitle(tr("%1 - Pixelator").arg(currentPath));
             }

             printAction->setEnabled(true);
             updateView();
         }
     }

     void MainWindow::printImage()
     {
     #ifndef QT_NO_PRINTER
         if (model->rowCount(QModelIndex())*model->columnCount(QModelIndex())
             > 90000) {
                 QMessageBox::StandardButton answer;
                 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);
         progress.setWindowModality(Qt::ApplicationModal);
         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);
         }
     #else
         QMessageBox::information(this, tr("Printing canceled"),
             tr("Printing is not supported on this Qt build"), QMessageBox::Cancel);
     #endif
     }

     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."));
     }

     void MainWindow::updateView()
     {
         view->resizeColumnsToContents();
         view->resizeRowsToContents();
     }