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

    /****************************************************************************
    **
    ** Copyright (C) 2004-2006 Trolltech ASA. All rights reserved.
    **
    ** This file is part of the documentation of the Qt Toolkit.
    **
    ** This file may be used under the terms of the GNU General Public
    ** License version 2.0 as published by the Free Software Foundation
    ** and appearing in the file LICENSE.GPL included in the packaging of
    ** this file.  Please review the following information to ensure GNU
    ** General Public Licensing requirements will be met:
    ** http://www.trolltech.com/products/qt/opensource.html
    **
    ** If you are unsure which license is appropriate for your use, please
    ** review the following information:
    ** http://www.trolltech.com/products/qt/licensing.html or contact the
    ** sales department at sales@trolltech.com.
    **
    ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
    ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
    **
    ****************************************************************************/

    #include <QtGui>

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

    MainWindow::MainWindow() : QMainWindow()
    {
        currentPath = QDir::home().absolutePath();
        model = new ImageModel(QImage(), this);

        QWidget *centralWidget = new QWidget;

        view = new QTableView;
        view->setShowGrid(false);
        view->horizontalHeader()->hide();
        view->verticalHeader()->hide();

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

        QLabel *pixelSizeLabel = new QLabel(tr("Pixel size:"));
        QSpinBox *pixelSizeSpinBox = new QSpinBox;
        pixelSizeSpinBox->setMinimum(1);
        pixelSizeSpinBox->setMaximum(32);
        pixelSizeSpinBox->setValue(12);

        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()));
        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)) {
            ImageModel *newModel = new ImageModel(image, this);
            view->setModel(newModel);
            delete model;
            model = newModel;

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

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

    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."));
    }

    void MainWindow::updateView()
    {
        for (int row = 0; row < model->rowCount(QModelIndex()); ++row)
            view->resizeRowToContents(row);
        for (int column = 0; column < model->columnCount(QModelIndex()); ++column)
            view->resizeColumnToContents(column);
    }