Qt 5.9 | Qt Widgets | MDI Example | mdichild.cpp Example File

Qt 5.9.9 Reference Documentation

# mdichild.cpp Example File

mainwindows/mdi/mdichild.cpp

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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();
      }