mdichild.cpp Example File

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  #include <QtWidgets>

  #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(), &QTextDocument::contentsChanged,
              this, &MdiChild::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(), &QTextDocument::contentsChanged,
              this, &MdiChild::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(QDir::toNativeSeparators(fileName), 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())
          return true;
      const QMessageBox::StandardButton 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);
      switch (ret) {
      case QMessageBox::Save:
          return save();
      case QMessageBox::Cancel:
          return false;
      default:
          break;
      }
      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();
  }