Qt 5.11 | Qt Widgets | Text Codecs Example | mainwindow.cpp Example File

Qt 5.11.3 Reference Documentation

# mainwindow.cpp Example File

tools/codecs/mainwindow.cpp

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      #include <QtWidgets>

      #include "mainwindow.h"
      #include "previewform.h"

      MainWindow::MainWindow()
      {
          textEdit = new QPlainTextEdit;
          textEdit->setLineWrapMode(QPlainTextEdit::NoWrap);
          setCentralWidget(textEdit);

          findCodecs();

          previewForm = new PreviewForm(this);
          previewForm->setCodecList(codecs);

          createMenus();

          setWindowTitle(tr("Codecs"));

          const QRect screenGeometry = QApplication::desktop()->screenGeometry(this);
          resize(screenGeometry.width() / 2, screenGeometry.height() * 2 / 3);
      }

      void MainWindow::open()
      {
          const QString fileName = QFileDialog::getOpenFileName(this);
          if (fileName.isEmpty())
              return;
          QFile file(fileName);
          if (!file.open(QFile::ReadOnly)) {
              QMessageBox::warning(this, tr("Codecs"),
                                   tr("Cannot read file %1:\n%2")
                                   .arg(QDir::toNativeSeparators(fileName),
                                        file.errorString()));
              return;
          }

          const QByteArray data = file.readAll();

          previewForm->setWindowTitle(tr("Choose Encoding for %1").arg(QFileInfo(fileName).fileName()));
          previewForm->setEncodedData(data);
          if (previewForm->exec())
              textEdit->setPlainText(previewForm->decodedString());
      }

      void MainWindow::save()
      {
          const QAction *action = qobject_cast<const QAction *>(sender());
          const QByteArray codecName = action->data().toByteArray();
          const QString title = tr("Save As (%1)").arg(QLatin1String(codecName));

          QString fileName = QFileDialog::getSaveFileName(this, title);
          if (fileName.isEmpty())
              return;
          QFile file(fileName);
          if (!file.open(QFile::WriteOnly | QFile::Text)) {
              QMessageBox::warning(this, tr("Codecs"),
                                   tr("Cannot write file %1:\n%2")
                                   .arg(QDir::toNativeSeparators(fileName),
                                        file.errorString()));
              return;
          }

          QTextStream out(&file);
          out.setCodec(codecName.constData());
          out << textEdit->toPlainText();
      }

      void MainWindow::about()
      {
          QMessageBox::about(this, tr("About Codecs"),
                  tr("The <b>Codecs</b> example demonstrates how to read and write "
                     "files using various encodings."));
      }

      void MainWindow::aboutToShowSaveAsMenu()
      {
          QString currentText = textEdit->toPlainText();

          foreach (QAction *action, saveAsActs) {
              QByteArray codecName = action->data().toByteArray();
              QTextCodec *codec = QTextCodec::codecForName(codecName);
              action->setVisible(codec && codec->canEncode(currentText));
          }
      }

      void MainWindow::findCodecs()
      {
          QMap<QString, QTextCodec *> codecMap;
          QRegularExpression iso8859RegExp("^ISO[- ]8859-([0-9]+).*$");
          QRegularExpressionMatch match;

          foreach (int mib, QTextCodec::availableMibs()) {
              QTextCodec *codec = QTextCodec::codecForMib(mib);

              QString sortKey = codec->name().toUpper();
              int rank;

              if (sortKey.startsWith(QLatin1String("UTF-8"))) {
                  rank = 1;
              } else if (sortKey.startsWith(QLatin1String("UTF-16"))) {
                  rank = 2;
              } else if ((match = iso8859RegExp.match(sortKey)).hasMatch()) {
                  if (match.captured(1).size() == 1)
                      rank = 3;
                  else
                      rank = 4;
              } else {
                  rank = 5;
              }
              sortKey.prepend(QLatin1Char('0' + rank));

              codecMap.insert(sortKey, codec);
          }
          codecs = codecMap.values();
      }

      void MainWindow::createMenus()
      {
          QMenu *fileMenu = menuBar()->addMenu(tr("&File"));
          QAction *openAct =
              fileMenu->addAction(tr("&Open..."), this, &MainWindow::open);
          openAct->setShortcuts(QKeySequence::Open);

          QMenu *saveAsMenu = fileMenu->addMenu(tr("&Save As"));
          connect(saveAsMenu, &QMenu::aboutToShow,
                  this, &MainWindow::aboutToShowSaveAsMenu);
          foreach (const QTextCodec *codec, codecs) {
              const QByteArray name = codec->name();
              QAction *action = saveAsMenu->addAction(tr("%1...").arg(QLatin1String(name)));
              action->setData(QVariant(name));
              connect(action, &QAction::triggered, this, &MainWindow::save);
              saveAsActs.append(action);
          }

          fileMenu->addSeparator();
          QAction *exitAct = fileMenu->addAction(tr("E&xit"), this, &QWidget::close);
          exitAct->setShortcuts(QKeySequence::Quit);

          menuBar()->addSeparator();

          QMenu *helpMenu = menuBar()->addMenu(tr("&Help"));
          helpMenu->addAction(tr("&About"), this, &MainWindow::about);
          helpMenu->addAction(tr("About &Qt"), qApp, &QApplication::aboutQt);
      }