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mainwindow.cpp Example File

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 ** ensure the GNU Lesser General Public License version 2.1 requirements
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 ** GNU General Public License Usage
 ** Alternatively, this file may be used under the terms of the GNU
 ** General Public License version 3.0 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
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 #include <QtGui>

 #include "mainwindow.h"
 #include "scribblearea.h"

     scribbleArea = new ScribbleArea;


     setWindowTitle(tr("Finger Paint"));
     resize(500, 500);

 void MainWindow::closeEvent(QCloseEvent *event)
     if (maybeSave()) {
     } else {

 void MainWindow::open()
     if (maybeSave()) {
         QString fileName = QFileDialog::getOpenFileName(this,
                                    tr("Open File"), QDir::currentPath());
         if (!fileName.isEmpty())

 void MainWindow::save()
     QAction *action = qobject_cast<QAction *>(sender());
     QByteArray fileFormat = action->data().toByteArray();

 void MainWindow::about()
     QMessageBox::about(this, tr("About Scribble"),
             tr("<p>The <b>Scribble</b> example shows how to use QMainWindow as the "
                "base widget for an application, and how to reimplement some of "
                "QWidget's event handlers to receive the events generated for "
                "the application's widgets:</p><p> We reimplement the mouse event "
                "handlers to facilitate drawing, the paint event handler to "
                "update the application and the resize event handler to optimize "
                "the application's appearance. In addition we reimplement the "
                "close event handler to intercept the close events before "
                "terminating the application.</p><p> The example also demonstrates "
                "how to use QPainter to draw an image in real time, as well as "
                "to repaint widgets.</p>"));

 void MainWindow::createActions()
     openAct = new QAction(tr("&Open..."), this);
     connect(openAct, SIGNAL(triggered()), this, SLOT(open()));

     foreach (QByteArray format, QImageWriter::supportedImageFormats()) {
         QString text = tr("%1...").arg(QString(format).toUpper());

         QAction *action = new QAction(text, this);
         connect(action, SIGNAL(triggered()), this, SLOT(save()));

     printAct = new QAction(tr("&Print..."), this);
     connect(printAct, SIGNAL(triggered()), scribbleArea, SLOT(print()));

     exitAct = new QAction(tr("E&xit"), this);
     connect(exitAct, SIGNAL(triggered()), this, SLOT(close()));

     clearScreenAct = new QAction(tr("&Clear Screen"), this);
     connect(clearScreenAct, SIGNAL(triggered()),
             scribbleArea, SLOT(clearImage()));

     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()));

 void MainWindow::createMenus()
     saveAsMenu = new QMenu(tr("&Save As"), this);
     foreach (QAction *action, saveAsActs)

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

     optionMenu = new QMenu(tr("&Options"), this);

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


 bool MainWindow::maybeSave()
     if (scribbleArea->isModified()) {
        QMessageBox::StandardButton ret;
        ret = QMessageBox::warning(this, tr("Scribble"),
                           tr("The image has been modified.\n"
                              "Do you want to save your changes?"),
                           QMessageBox::Save | QMessageBox::Discard
                           | QMessageBox::Cancel);
         if (ret == QMessageBox::Save) {
             return saveFile("png");
         } else if (ret == QMessageBox::Cancel) {
             return false;
     return true;

 bool MainWindow::saveFile(const QByteArray &fileFormat)
     QString initialPath = QDir::currentPath() + "/untitled." + fileFormat;

     QString fileName = QFileDialog::getSaveFileName(this, tr("Save As"),
                                tr("%1 Files (*.%2);;All Files (*)")
     if (fileName.isEmpty()) {
         return false;
     } else {
         return scribbleArea->saveImage(fileName, fileFormat);

Copyright © 2010 Nokia Corporation and/or its subsidiary(-ies) Trademarks
Qt 4.6.3