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mainwindow.cpp Example File
^{mainwindows/recentfiles/mainwindow.cpp}

 /****************************************************************************
 **
 ** Copyright (C) 2004-2007 Trolltech ASA. All rights reserved.
 **
 ** This file is part of the example classes 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 [email protected].
 **
 ** 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 "mainwindow.h"

 MainWindow::MainWindow()
 {
     setAttribute(Qt::WA_DeleteOnClose);

     textEdit = new QTextEdit;
     setCentralWidget(textEdit);

     createActions();
     createMenus();
     (void)statusBar();

     setWindowTitle(tr("Recent Files"));
     resize(400, 300);
 }

 void MainWindow::newFile()
 {
     MainWindow *other = new MainWindow;
     other->show();
 }

 void MainWindow::open()
 {
     QString fileName = QFileDialog::getOpenFileName(this);
     if (!fileName.isEmpty())
         loadFile(fileName);
 }

 void MainWindow::save()
 {
     if (curFile.isEmpty())
         saveAs();
     else
         saveFile(curFile);
 }

 void MainWindow::saveAs()
 {
     QString fileName = QFileDialog::getSaveFileName(this);
     if (fileName.isEmpty())
         return;

     if (QFile::exists(fileName)) {
         QMessageBox::StandardButton ret;
         ret = QMessageBox::warning(this, tr("Recent Files"),
                      tr("File %1 already exists.\n"
                         "Do you want to overwrite it?")
                      .arg(QDir::toNativeSeparators(fileName)),
                      QMessageBox::Yes | QMessageBox::Cancel);
         if (ret == QMessageBox::Cancel)
             return;
     }
     saveFile(fileName);
 }

 void MainWindow::openRecentFile()
 {
     QAction *action = qobject_cast<QAction *>(sender());
     if (action)
         loadFile(action->data().toString());
 }

 void MainWindow::about()
 {
    QMessageBox::about(this, tr("About Recent Files"),
             tr("The <b>Recent Files</b> example demonstrates how to provide a "
                "recently used file menu in a Qt application."));
 }

 void MainWindow::createActions()
 {
     newAct = new QAction(tr("&New"), this);
     newAct->setShortcut(tr("Ctrl+N"));
     newAct->setStatusTip(tr("Create a new file"));
     connect(newAct, SIGNAL(triggered()), this, SLOT(newFile()));

     openAct = new QAction(tr("&Open..."), this);
     openAct->setShortcut(tr("Ctrl+O"));
     openAct->setStatusTip(tr("Open an existing file"));
     connect(openAct, SIGNAL(triggered()), this, SLOT(open()));

     saveAct = new QAction(tr("&Save"), this);
     saveAct->setShortcut(tr("Ctrl+S"));
     saveAct->setStatusTip(tr("Save the document to disk"));
     connect(saveAct, SIGNAL(triggered()), this, SLOT(save()));

     saveAsAct = new QAction(tr("Save &As..."), this);
     saveAsAct->setStatusTip(tr("Save the document under a new name"));
     connect(saveAsAct, SIGNAL(triggered()), this, SLOT(saveAs()));

     for (int i = 0; i < MaxRecentFiles; ++i) {
         recentFileActs[i] = new QAction(this);
         recentFileActs[i]->setVisible(false);
         connect(recentFileActs[i], SIGNAL(triggered()),
                 this, SLOT(openRecentFile()));
     }

     exitAct = new QAction(tr("E&xit"), this);
     exitAct->setShortcut(tr("Ctrl+Q"));
     exitAct->setStatusTip(tr("Exit the application"));
     connect(exitAct, SIGNAL(triggered()), qApp, SLOT(closeAllWindows()));

     aboutAct = new QAction(tr("&About"), this);
     aboutAct->setStatusTip(tr("Show the application's About box"));
     connect(aboutAct, SIGNAL(triggered()), this, SLOT(about()));

     aboutQtAct = new QAction(tr("About &Qt"), this);
     aboutQtAct->setStatusTip(tr("Show the Qt library's About box"));
     connect(aboutQtAct, SIGNAL(triggered()), qApp, SLOT(aboutQt()));
 }

 void MainWindow::createMenus()
 {
     fileMenu = menuBar()->addMenu(tr("&File"));
     fileMenu->addAction(newAct);
     fileMenu->addAction(openAct);
     fileMenu->addAction(saveAct);
     fileMenu->addAction(saveAsAct);
     separatorAct = fileMenu->addSeparator();
     for (int i = 0; i < MaxRecentFiles; ++i)
         fileMenu->addAction(recentFileActs[i]);
     fileMenu->addSeparator();
     fileMenu->addAction(exitAct);
     updateRecentFileActions();

     menuBar()->addSeparator();

     helpMenu = menuBar()->addMenu(tr("&Help"));
     helpMenu->addAction(aboutAct);
     helpMenu->addAction(aboutQtAct);
 }

 void MainWindow::loadFile(const QString &fileName)
 {
     QFile file(fileName);
     if (!file.open(QFile::ReadOnly | QFile::Text)) {
         QMessageBox::warning(this, tr("Recent Files"),
                              tr("Cannot read file %1:\n%2.")
                              .arg(fileName)
                              .arg(file.errorString()));
         return;
     }

     QTextStream in(&file);
     QApplication::setOverrideCursor(Qt::WaitCursor);
     textEdit->setPlainText(in.readAll());
     QApplication::restoreOverrideCursor();

     setCurrentFile(fileName);
     statusBar()->showMessage(tr("File loaded"), 2000);
 }

 void MainWindow::saveFile(const QString &fileName)
 {
     QFile file(fileName);
     if (!file.open(QFile::WriteOnly | QFile::Text)) {
         QMessageBox::warning(this, tr("Recent Files"),
                              tr("Cannot write file %1:\n%2.")
                              .arg(fileName)
                              .arg(file.errorString()));
         return;
     }

     QTextStream out(&file);
     QApplication::setOverrideCursor(Qt::WaitCursor);
     out << textEdit->toPlainText();
     QApplication::restoreOverrideCursor();

     setCurrentFile(fileName);
     statusBar()->showMessage(tr("File saved"), 2000);
 }

 void MainWindow::setCurrentFile(const QString &fileName)
 {
     curFile = fileName;
     if (curFile.isEmpty())
         setWindowTitle(tr("Recent Files"));
     else
         setWindowTitle(tr("%1 - %2").arg(strippedName(curFile))
                                     .arg(tr("Recent Files")));

     QSettings settings("Trolltech", "Recent Files Example");
     QStringList files = settings.value("recentFileList").toStringList();
     files.removeAll(fileName);
     files.prepend(fileName);
     while (files.size() > MaxRecentFiles)
         files.removeLast();

     settings.setValue("recentFileList", files);

     foreach (QWidget *widget, QApplication::topLevelWidgets()) {
         MainWindow *mainWin = qobject_cast<MainWindow *>(widget);
         if (mainWin)
             mainWin->updateRecentFileActions();
     }
 }

 void MainWindow::updateRecentFileActions()
 {
     QSettings settings("Trolltech", "Recent Files Example");
     QStringList files = settings.value("recentFileList").toStringList();

     int numRecentFiles = qMin(files.size(), (int)MaxRecentFiles);

     for (int i = 0; i < numRecentFiles; ++i) {
         QString text = tr("&%1 %2").arg(i + 1).arg(strippedName(files[i]));
         recentFileActs[i]->setText(text);
         recentFileActs[i]->setData(files[i]);
         recentFileActs[i]->setVisible(true);
     }
     for (int j = numRecentFiles; j < MaxRecentFiles; ++j)
         recentFileActs[j]->setVisible(false);

     separatorAct->setVisible(numRecentFiles > 0);
 }

 QString MainWindow::strippedName(const QString &fullFileName)
 {
     return QFileInfo(fullFileName).fileName();
 }