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# mdichild.cpp Example File
mainwindows/mdi/mdichild.cpp

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     #include <QtGui>

     #include "mdichild.h"

     MdiChild::MdiChild()
     {
         setAttribute(Qt::WA_DeleteOnClose);
         isUntitled = true;
     }

     void MdiChild::newFile()
     {
         static int sequenceNumber = 1;

         isUntitled = true;
         curFile = tr("document%1.txt").arg(sequenceNumber++);
         setWindowTitle(curFile + "[*]");

         connect(document(), SIGNAL(contentsChanged()),
                 this, SLOT(documentWasModified()));
     }

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

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

         setCurrentFile(fileName);

         connect(document(), SIGNAL(contentsChanged()),
                 this, SLOT(documentWasModified()));

         return true;
     }

     bool MdiChild::save()
     {
         if (isUntitled) {
             return saveAs();
         } else {
             return saveFile(curFile);
         }
     }

     bool MdiChild::saveAs()
     {
         QString fileName = QFileDialog::getSaveFileName(this, tr("Save As"),
                                                         curFile);
         if (fileName.isEmpty())
             return false;

         return saveFile(fileName);
     }

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

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

         setCurrentFile(fileName);
         return true;
     }

     QString MdiChild::userFriendlyCurrentFile()
     {
         return strippedName(curFile);
     }

     void MdiChild::closeEvent(QCloseEvent *event)
     {
         if (maybeSave()) {
             event->accept();
         } else {
             event->ignore();
         }
     }

     void MdiChild::documentWasModified()
     {
         setWindowModified(document()->isModified());
     }

     bool MdiChild::maybeSave()
     {
         if (document()->isModified()) {
             QMessageBox::StandardButton ret;
             ret = QMessageBox::warning(this, tr("MDI"),
                          tr("'%1' has been modified.\n"
                             "Do you want to save your changes?")
                          .arg(userFriendlyCurrentFile()),
                          QMessageBox::Save | QMessageBox::Discard
                          | QMessageBox::Cancel);
             if (ret == QMessageBox::Save)
                 return save();
             else if (ret == QMessageBox::Cancel)
                 return false;
         }
         return true;
     }

     void MdiChild::setCurrentFile(const QString &fileName)
     {
         curFile = QFileInfo(fileName).canonicalFilePath();
         isUntitled = false;
         document()->setModified(false);
         setWindowModified(false);
         setWindowTitle(userFriendlyCurrentFile() + "[*]");
     }

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